DoD STTR 23.A

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Computing and Software OBJECTIVE: Develop an innovative tool that can autonomously generate a common mesh from Computer-Aided Design (CAD) geometry with adaptive global and local refinement capabilities for coupled aero-thermal-structural analysis and optimization to enable Virtual Reality (VR)-based real-time interactive designs. DESCRIPTION: Digital engineering for aircraft development can be accelerated by multidisciplinary design, analysis, and optimization (MDAO). The core component of MDAO for hypersonic aircraft is the multi-physics simulations involving the interplay between high-speed aerodynamics, structural dynamics, and thermodynamics. Aero-structure-thermal simulations could dramatically reduce the ground-based and in-flight tests as more capable high-performance computing (HPC) hardware can afford higher resolutions of geometrical and physical complexities — i.e., if a 10 cm accuracy in the 1980s for an aircraft was the standard, 1 mm for the geometry and 1 µm in the boundary layer resolution is now commonplace. However, these increasing geometrical accuracy requirements and physical complexities pose grand challenges in mesh generation [Refs 1–2]. According to the NASA CFD Vision 2030 [Ref 3], mesh generation and adaptivity persist as significant bottlenecks in computational fluid dynamics (CFD) workflow. On the one hand, autonomous and geometry-aware mesh generation techniques are still lacking. Generating high-quality meshes by existing approaches [Refs 4–7] from complex CAD models of aircraft still involves time-consuming human intervention, and the resulting meshes do not retain the parameterization of the geometry. The geometric discrepancy can lead to significant errors in the prediction of critical physics, such as shock-boundary layer interaction and fatigue/damage in structures. On the other hand, mesh adaption can substantially save CPU time, memory requirement, and storage space. However, controlling the error and generating the optimal mesh for a given accuracy is challenging [Ref 9]. Automatic mesh adaption with local and global refinements in critical regions without prior knowledge of the problem is also a difficult task [Ref 1]. Resolving these challenges, which have been hampering automatic and adaptive mesh generation for complex geometries, will dramatically facilitate simulation-based aircraft design and optimization and have a far-reaching impact on Navy’s missions. An adaptive, common mesh generation tool is needed to facilitate the MDAO to accelerate aircraft development. The effectiveness of the tool is measured by reducing the time, and therefore cost, required to develop the multi-physics meshes. The tool should enable autonomously-generated geometry-aware mesh generation and adaption, which can be integrated into the simulation tools of aircrafts involving CFD (e.g., hypersonic flows), fluid-structure interaction (FSI), fatigue/damage, and thermodynamics. The developed tool should be flexible, i.e., able to handle various air vehicle geometries. The tool should allow automatic mesh adaption with no or minimal dependence on prior knowledge in multi-physics simulations for critical quantities at critical locations, such as shock and turbulence in the fluid domain, as well as mechanical and thermal variables in the structural domain. The mesh generation and adaption tool should have quantification metrics, control strategies, and error estimates to assist the user in obtaining reliable simulation results with the first mesh. It should also address both body-fitted meshes and nonbody-fitted meshes, as the latter meshes are essential for the feasibility, as well as efficiency of MDAO problems where the geometry undergoes large shape and/or topological changes, and the multidisciplinary simulations involve large structural displacements, rotations and/or deformations [Ref 10]. The toolkit should enhance the user’s experience with virtual reality by improving visual understanding of the mesh with respect to the geometry through the interaction of the various physics. PHASE I: Demonstrate the capability of the mesh generation tool and its integration with a prototype simulation toolkit design. Illustrate a workflow for a multidisciplinary analysis along with the local-global coupling for a representative aircraft structural component subjected to a given operational profile. Demonstrate the effectiveness and cost saving in design iteration in comparison with a conventional approach. Show the autonomous capability of meshing complex CAD models and adaption upon mesh generation, capturing critical features such as shocks or stress concentrations. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Develop, demonstrate, and validate the prototype design from Phase I. Fully integrate the mesh generation technique with multi-physics simulation tools of aero-structure-thermal analysis for aircraft development. Quality metrics for the fully functional software product should include the automatic meshing adaptivity to capture the local physics and meshing transformation between different physical problem descriptions. Incorporate virtual reality to enhance the user’s understanding of the mesh and how it relates to the geometry. The virtual reality should also enhance understanding of the solution and the interactions of various physics. Show the applicability of the tool using commercially available or open literature CAD data for the original design and specifications. Demonstrate its advantages in terms of cost, accuracy, and robustness in the context of MDAO to reach an optimized design under fluid-thermal-mechanical loading. PHASE III DUAL USE APPLICATIONS: Demonstrate capability to model a flight test event with inclusion of fluid-thermal-mechanical loading and show it provides risk reduction for the test event. The use of multidisciplinary simulations is becoming more common for commercial products. Beyond the natural need of the commercial aerospace industry, many other industries are interested in multi-physics simulations. Civil engineering needs to consider fluid-structures interactions. Fluid-thermal interactions are critical for electronics. The automotive industry is interested in fluid-thermal-structural analysis, with rapid turnaround. These industries will benefit from more capable and quicker multidisciplinary mesh generation. REFERENCES: 1. Alauzet, F., & Loseille, A. (2016). A decade of progress on anisotropic mesh adaptation for computational fluid dynamics. Computer-Aided Design, 72, 13-39. https://doi.org/10.1016/j.cad.2015.09.005 2. Karman, S. L., Wyman, N., & Steinbrenner, J. P. (2017). Mesh generation challenges: A commercial software perspective. In 23rd AIAA Computational Fluid Dynamics Conference (p. 3790). https://doi.org/10.2514/6.2017-3790 3. Slotnick, J. P., Khodadoust, A., Alonso, J., Darmofal, D., Gropp, W., Lurie, E. and Mavriplis, D. J. (2014). CFD vision 2030 study: a path to revolutionary computational aerosciences. https://ntrs.nasa.gov/citations/20140003093 4. Aftosmis, M., Berger, M., & Murman, S. (2004, May). Applications of space-filling-curves to cartesian methods for cfd. In 42nd AIAA Aerospace Sciences Meeting and Exhibit (p. 1232). https://doi.org/10.2514/6.2004-1232 5. Löhner, R., & Parikh, P. (1988). Generation of three-dimensional unstructured grids by the advancing-front method. International Journal for Numerical Methods in Fluids, 8(10), 1135-1149. https://doi.org/10.1002/fld.1650081003 6. Weatherill, N. P., & Hassan, O. (1994). Efficient three-dimensional Delaunay triangulation with automatic point creation and imposed boundary constraints. International journal for numerical methods in engineering, 37(12), 2005-2039. https://doi.org/10.1002/nme.1620371203 7. Yerry, M. A., & Shephard, M. S. (1984). Automatic three-dimensional mesh generation by the modified-octree technique. International Journal for Numerical Methods in Engineering, 20(11), 1965-1990. https://doi.org/10.1002/nme.1620201103 8. Hughes, T. J., Cottrell, J. A., & Bazilevs, Y. (2005). Isogeometric analysis: CAD, finite elements, NURBS, exact geometry and mesh refinement. Computer methods in applied mechanics and engineering, 194(39-41), 4135-4195. https://doi.org/10.1016/j.cma.2004.10.008 9. Park, M. A., Kleb, W. L., Jones, W. T., Krakos, J. A., Michal, T. R., Loseille, A., Haimes, R., & Dannenhoffer, J. (2019). Geometry modeling for unstructured mesh adaptation. In AIAA Aviation 2019 Forum (p. 2946). https://doi.org/10.2514/6.2019-2946 10. Ho, J. B., & Farhat, C. (2021). Aerodynamic shape optimization using an embedded boundary method with smoothness guarantees. In AIAA Scitech 2021 Forum (p. 0280). https://doi.org/10.2514/6.2021-0280 KEYWORDS: Mesh Generation; Adaptive Meshing; Global-local modeling; Multidisciplinary Analysis; multi-disciplinary design, analysis, and optimization; virtual reality

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics; Integrated Network Systems-of-Systems OBJECTIVE: Develop modeling approach for designing, maintaining, and supporting air and sea platform digital and analog fiber optic communications technology. DESCRIPTION: The use of optical fiber on air, surface ship, and undersea platforms is pervasive, and is an enabling technology. Current military electronics, electro-optic, communications, radar, and electronic warfare systems require ever-increasing bandwidths, while simultaneously demanding reductions in space, weight, and power (SWaP). The effectiveness of these systems hinges on optical communication components that realize sufficient link budget, dynamic range, and compatibility with military surface ship, undersea platform, and aircraft maintenance environments [Refs 1-5]. Future digital and analog/radio frequency (RF) signal transmission rates and frequencies have increased to the point where fiber optics is the only medium with the capacity and low loss for maintaining communications signal integrity. Maintainability and supportability are well-known operational availability drivers for fiber optics technology deployment on military platforms [Ref 6]. Key systems engineering design considerations include architecture (openness, modularity, scalability, and upgradeability), reliability, maintainability, and supportability. Supportability infrastructure is difficult to add on after the design is established, and therefore should be included in the systems engineering design process. Key fiber optics systems engineering design considerations include architecture, reliability, maintainability, and supportability. Integrating the disparate interfaces associated with digital and analog/RF fiber optic systems, and a model-based engineering approach, requires significant digital engineering research and innovation. Although the Navy has complete knowledge of the required connections and interfaces for digital and analog/RF fiber optics, there is no model-based approach to selecting components (connectors, cable, termini, transmitters, receivers), support equipment (maintenance sets), training, and the required supportability and maintainability concepts. MIL-HDBK-217 requires modernization for fiber optics reliability engineering [Ref 7]. This digital engineering research effort should develop models that include all of the platform components, support equipment, associated fleet maintainer training, reliability data, and digital and analog/RF fiber optic system design engineering principles. Digital engineering research should capture approaches to minimize the number and diversity of parts and interfaces, and be applicable to aircraft, surface ship, and undersea platform specific model-based system-engineering models. Digital engineering research is also required to understand how to best utilize the existing CAMEO Systems Modeler tool [Ref 8] and Systems Modeling Language (SysML) [Ref 9] for ship and aircraft fiber optics hardware integration, relevant use cases, use of existing standards, digital and analog/RF link design principles, and use of existing and emerging components. Fiber optics supportability cuts across reliability, maintainability, and the supply chain to facilitate detection, isolation, and timely repair/replacement of system anomalies. Typical supportability features include prognostics, diagnostics, skill levels, support equipment footprint, training, maintenance data collection, compatibility, packaging and handling, and other factors that contribute to an optimum environment for sustaining a fiber optic system. The ability to sustain the operation of a fiber optic system on a surface ship, undersea platform or aircraft, is established by the inherent supportability of the system and the processes used to sustain the functions and capabilities of the system in the context of the end user. The focus of sustainment planning is to influence the inherent supportability of the system and to plan the sustainment capabilities and processes used to sustain system operations. Sustainment influence requires an understanding of the system missions and mission profiles and to provide rationale for functional and performance priorities. Understanding the rationale paves the way for decisions about necessary tradeoffs between system performance, with impact on the cost effectiveness of system operation, maintenance, and logistics support. There is no single list of sustainment considerations or a specific way of grouping system operation, maintenance, and logistics support, as they are highly inter-related. They include compatibility, transportability, the actual maintenance environment, diagnostics and prognostics (including real-time maintenance data collection and built-in test), and corrosion protection and mitigation. Fiber optics maintainability considerations encompass modularity, interoperability, physical accessibility, training, testing, and human systems integration. Maintainability generally requires balancing the maintenance requirement over the life cycle with minimal user workload. The emphasis on maintainability is to reduce the maintenance burden and supply chain by reducing time, personnel, tools, test equipment, training, facilities, and cost to maintain the system. Maintainability engineering includes the activities, methods, and practice to design minimal system maintenance requirements and associated costs for preventative and corrective maintenance, as well as servicing and calibration activities. Maintainability should be a designed-in capability and not an add-on option, because good maintenance procedures cannot overcome poor system and equipment maintainability design. The primary objective is to reduce the time and complexity for a properly trained maintainer to detect, isolate and repair a failure. PHASE I: Collect research data on fiber optic components, link-loss power budget methodologies, system design concepts, maintenance concepts, support equipment concepts, and overall maintainability and supportability. Using SysML, create handoff between reliability, maintainability, and supportability within the bounds of the military platform fiber optic systems engineering process. Identify key risk areas for tracing lower level fiber optic system designs to higher level supportability and maintainability considerations to realize desired life cycle performance, and mitigate these risks using digital engineering research concepts and modeling tools. Demonstrate operational suitability trade-offs of model-based system engineering approaches to fiber optic system design and support. The Phase I effort shall include plans to be developed under Phase II. PHASE II: Develop digital engineering-based prototype software to enable modeling of fiber optics integration in the context of supportability and maintainability. Optimize the model designs using representative cases from ships and aircraft. Build and test support equipment prototypes based on results from the models. Determine the efficacy of the entire support concept. Deliver the SysML model and digital engineering software. PHASE III DUAL USE APPLICATIONS: Finalize the application. Verify and validate the application in model-based systems engineering environments that are applicable to aerospace, surface ship, and undersea platforms. Transition to applicable naval platforms. Commercial sector telecommunication systems, fiber optic networks, and data centers could benefit from the development of this application. REFERENCES: 1. Binh, L. N. (2017, July 26) Advanced digital optical communications (2nd ed.). CRC Press. https://www.worldcat.org/title/advanced-digital-optical-communications/oclc/1053852857?referer=br&ht=edition 2. Urick, V. J., Williams, K. J. & McKinney, J. D. (2015). Fundamentals of microwave photonics. John Wiley & Sons. https://www.worldcat.org/title/fundamentals-of-microwave-photonics/oclc/895388531&referer=brief_results 3. AS-3 Fiber Optics and Applied Photonics Committee. (2018, January 23). AS5603A Digital Fiber Optic Link Loss Budget Methodology for Aerospace Platforms. Warrendale: SAE. https://www.sae.org/standards/content/as5603a/ 4. AS-3 Fiber Optics and Applied Photonics Committee. (2018, January 23). AS5750A Loss Budget Specification for Fiber Optic Links. Warrendale: SAE. https://www.sae.org/standards/content/as5750a/ 5. Naval Sea Systems Command. (1997, October 10). MIL-STD-2052A: Department of Defense design criteria standard: fiber optic systems design. Department of Defense. http://everyspec.com/MIL-STD/MIL-STD-2000-2999/MIL-STD-2052A_9141/ 6. Department of Defense. (1991, December 2). MIL-HDBK-217F: Military Handbook: Reliability prediction of electronic equipment. Department of Defense. http://everyspec.com/MIL-HDBK/MIL-HDBK-0200-0299/MIL-HDBK-217F_14591/ 7. CATIA. (n.d.). Cameo systems modeler. 3DS.com. Retrieved August 25, 2021, from https://www.nomagic.com/products/cameo-systems-modeler 8. Defense Supply Center Columbus. (2010, May 28). MIL-STD-1678/1: Department of Defense standard practice: Fiber optic cabling systems requirements and measurements (Part 1: Design, installation and maintenance requirements). Department of Defense. http://everyspec.com/MIL-STD/MIL-STD-1600-1699/MIL-STD-1678-1_20346/ 9. The Object Management Group. (n.d.). What is SYSML? OMG Systems Modeling Language. Retrieved August 25, 2021, from https://www.omgsysml.org/what-is-sysml.htm KEYWORDS: Fiber optics; system design; supportability; maintainability; model-based systems engineering; digital engineering

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Computing and Software OBJECTIVE: Improve time-varying modeling and simulation capabilities to couple representative reactive sand particulates with modern propulsion systems, including inlet and turbomachinery. DESCRIPTION: Naval aircraft powered by gas turbine engines experience safety, performance, and reliability concerns when operating in degraded visual environments with significant concentrations of reactive dust and sand. Sand particulates—including sand, salt, dust, and volcanic ash that aren't filtered or separated by an existing inlet or engine mounted filtration system—are ingested into the gas turbine engine. Improved modeling and simulation tools will help better characterize the sand particulate impact on turbomachinery within aircraft propulsion systems. Current systems can have safety impacts when operating in sand and dust related to sand deposition within the turbine leading to engine surge and potential loss of aircraft. Engine reliability is heavily impacted by sand ingestion, which can lead to faster engine deterioration with significant life cycle cost. Improved understanding of the impacts and design changes using modeling tools would have a positive impact on capability, performance, and cost. Ingested particles can degrade compressor performance via surface erosion, deform leading and trailing edges of blade airfoils, and open rotor tip-clearances [Ref 4]. Sand particulates that make it through to the combustor are elevated to high temperatures and can deposit on turbine airfoil surfaces—shrinking throat clearances—or deposit on turbine shroud and degrade turbine tip clearances. Sand particulates can also enter cooling passages and create deposits that block cooling flows resulting in exceedance of airfoil material temperature limits. This can affect both military and commercial aircraft and rotorcraft. Sand ingestion and deposition can be further impacted by relevant sand properties (geology, chemical composition, size distribution, shape, concentration) [Ref 3]. Airflow restrictions can occur rapidly on wing, and result in sand related operability impacts that can cause safety issues with undesired engine surge and stall events. Additionally, performance loss from significant turbine airfoil damage typically cannot be recovered entirely via engine wash or other maintenance procedures. This can lead to more frequent engine replacements and an overall reliability concern for the propulsion system. Complex propulsion systems of interest include inlets, inertial separators, hot and cold rotating turbomachinery with and without secondary cooling air flow, as well as the coupling of multiple of these components. Current state-of-the-art modeling and simulation tools typically couple steady-state Reynold's averaged navier stokes (RANS) computational fluid dynamics (CFD) solvers to a discrete particle tracking tool. This method has several disadvantages, including inaccurate inclusion or modeling of turbulent particle dispersion, limited particle-to-particle collisions and interaction, simplified particle shapes that affect drag estimates and wall-impacts/rebounds, one-way coupled particles that don't affect gas aerodynamics, and deposition predictions that use frozen geometry shapes and wall properties that can't change in time as the deposit size increases. Unsteady Large Eddy Simulation (LES) typically include more rich physics-based models that incorporate more of the above RANS deficiencies; however, they can also be computationally expensive and too long to impact design iterations or active acquisition programs. Additionally, the vast amount of data available from a resolved simulation with millions of particulates is frequently difficult to post-process and analyze efficiently. Efficient algorithms and post-processing methodologies to cumulatively understand time-accurate statistical measures of the ingested sand particulates are required. Modeling and simulation tools need to be improved to be able to accurately predict time-varying particle trajectories, wall-impacts, surface erosion, and surface deposition within inlet systems and engine turbomachinery [Ref 5]. Improvements to accuracy and confidence of modeling methodologies, as well as significant improvements to computational cost and efficiency to be able to impact a typical design cycle, are desired. The proposed approach's accuracy and applicability to relevant, complex propulsion systems should be demonstrated via comparisons against available (published), acquired experimental data, or government-provided test data. A focus on robust, parallel, highly efficient software improvements that can be utilized for complex geometries (such as inertial separators and rotating turbomachinery with secondary and cooling flows) with relevant sand particle constituents, size distributions, and cloud concentrations [Ref 1], is required. Although not required, it is highly recommended that the proposer work in coordination with the original equipment manufacturer (OEM) to ensure proper design and to facilitate transition of the final technology. PHASE I: Demonstrate understanding of relevant sand properties, including those of reactive sand and dust (geology, chemical composition, size distribution, shape, concentration). Demonstrate and validate the use of a commercially available CFD solver that has been coupled to incorporate sand particulates. Validate selected aerodynamic software on relevant turbomachinery geometry. Define the approach to be used in Phase II for improved physics modeling and robust, efficient solver development that can be applied to complex propulsion systems. Provide risk mitigation information. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Develop and demonstrate the prototype improved sand and dust modeling capability. Show efficient integration of reactive capability with existing, commercially available CFD software. Evaluate and report on the tool improvements impact on accuracy against available (published), acquired experimental data, or government-provided test data. Provide clear documentation of the theory, applied models and methods, assumptions, limitations, and instructions for use of the coupled aerodynamic and sand predictive tool. Demonstrate computational efficiency and robustness on DoD High Performance Computing assets. PHASE III DUAL USE APPLICATIONS: Transition developed tool and capability to government for implementation on fleet aircraft. Modify tools based on feedback from use within a DoD acquisition program. Support the application of advanced, mature, robust tools on aircraft engine and inlet analysis and redesign. Commercial aircraft engines experience sand and dust deterioration over long-time exposures. This can also impact performance and reliability of commercial engines. Improved modeling and simulation for better understanding and design methodologies will also impact aircraft engines for rotary- and fixed-wing commercial aircraft. REFERENCES: 1. Cowherd, C. (2007). MRI project no. 110565: Sandblaster 2 support of see-through technologies for particulate brownout. Midwest Research Institute. https://apps.dtic.mil/sti/pdfs/ADA504965.pdf 2. Guha, A. (2008). Transport and deposition of particles in turbulent and laminar flow. Annu. Rev. Fluid Mech., 40, 311-341. https://doi.org/10.1146/annurev.fluid.40.111406.102220 3. Walock, M. J., Barnett, B. D., Ghoshal, A., Murugan, M., Swab, J. J., Pepi, M. S., Hopkins, P. D., Gazonas, G., Rowe, C., & Kerner, K. (2017). Micro-scale sand particles within the hot section of a gas turbine engine. Mechanical Properties and Performance of Engineering Ceramics and Composites XI, 606, 159. https://doi.org/10.1002/9781119320104.ch14 4. Hamed, A., Tabakoff, W. C. and Wenglarz, R. V. “Erosion and deposition in turbomachinery. Journal of propulsion and power, 22(2), 350-360. https://doi.org/10.2514/1.18462 5. Jain, N., Le Moine, A., Chaussonnet, G., Flatau, A., Bravo, L., Ghoshal, A., Walock, M. J., Murugan, M., & Khare, P. (2021). A critical review of physical models in high temperature multiphase fluid dynamics: turbulent transport and particle-wall interactions. Applied Mechanics Reviews. https://doi.org/10.1115/1.4051503 6. DoD High Performance Computing Modernization Program (DoD HPCMP). https://centers.hpc.mil/systems/hardware.html KEYWORDS: Gas Turbine Engines; Degraded Visual Environments; Sand and Dust Ingestion; Computational-Fluid Dynamics; High Performance Computing; Sand Deposition

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Develop a digital twin (DT)-based system that can autonomously tailor local microstructure, heal defects, and minimize residual stresses and surface roughness in near real-time to assure repeatable, reliable, and optimal fatigue performance for additive manufactured (AM) metallic aerospace components. DESCRIPTION: Additive manufacturing (AM) has attained significant popularity in research and application fields such as aerospace, automobile, maritime, biomedical, and other industrial sectors. AM processes are capable of depositing near-net-shape complex geometries; but major drawbacks of the AM materials remain, including anisotropy, surface irregularities, residual stresses, and defects (such as porosity, microcracks, inclusions, dislocations, etc.). These drawbacks significantly influence the static and dynamic mechanical properties of a material. As a result, the AM parts still lack quality consistency and repeatability. While post-processing such as Hot Isotropic Pressing (HIP) could enhance performance for some alloys, it could lead to additional cost and production time. The various defects in AM processing can arise due to many causes, and significant attention has been given to different strategies to ameliorate these defects. Two significant types of defects observed from AM processing are lack-of-fusion (LOF) defects and gas porosity. LOF occurs when an insufficient amount of energy is applied to melt a specific location of a powderbed. This is directly influenced by site-specific processing parameters, such as laser power, hatch spacing, and scan speed. A rescanning strategy in the region with the LOF may eliminate the LOF defects. Gas porosity is often spherical due to gas trapped in the raw metal powder particles or trapped inert gas during the AM processing. It has been shown that gas porosity can be minimized with increasing scan speed and appropriate power level. Another challenge that causes build failures and poor part quality is large residual stresses due to the high cooling rates in AM processing. However, recent research has found that rescanning the top layer reduces residual stresses near that surface. In order to enable in-situ controlling the quality of the build, a monitoring and control system is necessary. There are several in-situ monitoring methods that have been demonstrated. For example, in order to capture the porosity, a high-speed camera and a photodiode were used to measure the dimensions of the melt pool condition and the mean emitted radiation. A two-color pyrometer was used to relate the consolidation phenomena with the surface temperature and to understand the solidification process of the molten powder. However, the collected data could be enormous (~0.5 Terabytes per build) requiring a large amount of storage and fast computational algorithms. Furthermore, the level of accuracy to detect and classify defects/anomalies still needs significant improvement, especially minimizing false positives and negatives. Once the undesirable state of the deposit is monitored and sensed, near real-time healing and tailoring of the deposit are needed. A close-loop feedback laser system, such as a laser with shaped beam profiles, may be used for in-situ treatment of the deposit, as well as preventing material spattering and defects. For example, it was reported that equiaxed grains occupied a larger area fraction, and texture was reduced in parts built using an elliptical beam, compared to those built using a Gaussian beam. Laser power and wavelength control could also tailor the cooling rate to prevent cracking and improve the mechanical properties of the part. The use of ring distributed power in welding can result in a decrease of laser penetration depth, along with huge spatter reduction observed on the deposited bead and surrounding area. However, a near real-time close-loop feedback system also requires robust reduced-order/surrogate modeling coupled with Artificial Intelligence (AI)/Machine Learning (ML) that link powders, process parameters, microstructure, and site-specific properties at the component level, including the effects of build orientation, laser-material interaction, and specific part geometry. These are the key elements of a DT-based system. The Navy requires an integrated DT-based system that can provide near real-time machine control for fully autonomous adaptive AM processing of metallic aerospace components. The system should be able to: (a) locally re-scan and re-melt; (b) autonomously adjust and control deposited energy density including laser power/intensity, spot size, and beam shape/profile, (de)focusing, scanning speed and pattern, hatch spacing, layer thickness, and interlayer delay time; and (c) build time of a complete part should not exceed by more than 20% compared to the traditional fixed parameter pre-set method. It is envisioned that such an in-situ tailoring/healing system will not only significantly improve the fatigue life performance comparable to wrought alloys, but also assure the repeatability and reliability of AM structural parts. PHASE I: Demonstrate feasibility of a feedback control concept that integrates with a beam shaping laser system, sensors, ML-enabled monitoring and control methodologies, and reduced-order modeling (ROM) for Laser Powder Bed Fusion (LPBF) system. Demonstrate the feasibility of healing and tailoring the AM deposit. A detailed plan should be laid out to perform the validation of the effectiveness of the concept with implementation for a metallic alloy such as AlSi10Mg aluminum. The concept should have the potential to be developed into a full-scale, near real-time, in-situ monitoring and control system of an AM process to improve fatigue properties in Phase II. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Develop, demonstrate, and validate the prototype system developed in Phase I. Fully develop and validate the ML-enabled monitoring and control system with reduced-order modeling for a laser-based AM process to efficiently and robustly heal and tailor the AM deposited material properties, based on the optimized AM process parameters for additional selected materials, such as Ti6Al4V, SS316L, and aluminum alloys. Demonstrate its capability of manufacturing aircraft components with complex geometry and tailored performance. PHASE III DUAL USE APPLICATIONS: Fully develop the advanced monitoring and control system coupled with reduced order models for various laser-based AM processes to fabricate naval aircraft components that can be integrated into the fleet. Conduct final component-level testing to achieve the geometry and material property of AM components meeting the Navy’s needs. The monitoring and control system will be directly applicable to a wide range of AM process methods and machines due to the high amount of usage of AM parts in the commercial aerospace and medical industries. The oil and gas, automotive, and shipping industries could also benefit from this developed technology. REFERENCES: 1. Liu, M., Fang, S., Dong, H., & Xu, C. (2021). Review of digital twin about concepts, technologies, and industrial applications. Journal of Manufacturing Systems, 58, 346-361. https://doi.org/10.1016/j.jmsy.2020.06.017 2. Gunasegaram, D. R., Murphy, A. B., Matthews, M. J., & DebRoy, T. (2021). The case for digital twins in metal additive manufacturing. Journal of Physics: Materials, 4(4), 040401. https://iopscience.iop.org/article/10.1088/2515-7639/ac09fb 3. Mukherjee, T., & DebRoy, T. (2019). A digital twin for rapid qualification of 3D printed metallic components. Applied Materials Today, 14, 59-65. https://doi.org/10.1016/j.apmt.2018.11.003 4. Kim, F. H., & Moylan, S. P. (2018, May). NIST advanced manufacturing series 100-16: Literature review of metal additive manufacturing defects. U.S. Department of Commerce. https://doi.org/10.6028/NIST.AMS.100-16 5. Roehling, T. T., Shi, R., Khairallah, S. A., Roehling, J. D., Guss, G. M., McKeown, J. T., & Matthews, M. J. (2020). Controlling grain nucleation and morphology by laser beam shaping in metal additive manufacturing. Materials & Design, 195, 109071. https://doi.org/10.1016/j.matdes.2020.109071 6. Kim, J., Ji, S., Yun, Y. S., & Yeo, J. S. (2018). A review: melt pool analysis for selective laser melting with continuous wave and pulse width modulated lasers. Applied Science and Convergence Technology, 27(6), 113-119. https://doi.org/10.5757/ASCT.2018.27.6.113 7. Gunasegaram, D. R., Murphy, A. B., Barnard, A., DebRoy, T., Matthews, M. J., Ladani, L., & Gu, D. (2021). Towards developing multiscale-multiphysics models and their surrogates for digital twins of metal additive manufacturing. Additive Manufacturing, 102089. https://doi.org/10.1016/j.addma.2021.102089 8. Yadav, P., Rigo, O., Arvieu, C., Le Guen, E., & Lacoste, E. (2020). In situ monitoring systems of the SLM process: On the need to develop machine learning models for data processing. Crystals, 10(6), 524. https://doi.org/10.3390/cryst10060524 9. Adnan, M., Lu, Y., Jones, A., Cheng, F.-T., & Yeung, H. (2020). A new architectural approach to monitoring and controlling AM processes. Applied Sciences, 10(18), 6616. https://doi.org/10.3390/app10186616 10. Liu, C., Le Roux, L., Ji, Z., Kerfriden, P., Lacan, F., & Bigot, S. (2020). Machine Learning-enabled feedback loops for metal powder bed fusion additive manufacturing. Procedia Computer Science, 176, 2586-2595. https://doi.org/10.1016/j.procs.2020.09.314 11. Vandone, A., Baraldo, S., & Valente, A. (2018). Multisensor data fusion for additive manufacturing process control. IEEE Robotics and Automation Letters, 3(4), 3279-3284. https://doi.org/10.1109/LRA.2018.2851792 12. Zhu, Q., Liu, Z., & Yan, J. (2021). Machine learning for metal additive manufacturing: predicting temperature and melt pool fluid dynamics using physics-informed neural networks. Computational Mechanics, 1-17. https://doi.org/10.1007/s00466-020-01952-9 13. McCann, R., Obeidi, M. A., Hughes, C., McCarthy, É., Egan, D. S., Vijayaraghavan, R. K., Joshi, A. M., Acinas Garzon, V., Dowling, D. P., McNally, P. J., & Brabazon, D. (2021). In-situ sensing, process monitoring and machine control in Laser Powder Bed Fusion: A review. Additive Manufacturing, 102058. https://doi.org/10.1016/j.addma.2021.102058 14. Du, Y., Mukherjee, T., & DebRoy, T. (2021). Physics-informed machine learning and mechanistic modeling of additive manufacturing to reduce defects. Applied Materials Today, 24, 101123. https://doi.org/10.1016/j.apmt.2021.101123 15. Pandita, P., Ghosh, S., Gupta, V. K., Meshkov, A., & Wang, L. (2021). Application of deep transfer learning and uncertainty quantification for process identification in powder bed fusion. ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part B: Mechanical Engineering, 8(1), 011106. https://doi.org/10.1115/1.4051748 KEYWORDS: Additive Manufacturing; Digital Twin; In-situ Monitoring; Closed-Loop Feedback Control; Artificial Intelligence/Machine Learning; Reduced-Order Modeling

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials OBJECTIVE: Develop a time-resolved sensor system for measuring gas dynamic and compositional characteristics of high-temperature/high-velocity engine exhaust plumes. DESCRIPTION: Time-resolved measurements in high-temperature and high-velocity exhaust plumes are necessary to better understand transient phenomena including startup/shut down, combustion instabilities, and flow nonuniformity. Measurement parameters of interest in exhaust plumes include temperature, pressure, velocity, combustion efficiency, and gas composition. High-temperature, high-velocity exhaust plumes present a uniquely challenging measurement environment. Wetted sensors, such as thermocouples and pressure transducers, degrade rapidly in reactive, particle-laden, high-temperature, high-velocity plume flows, emphasizing a need for noninvasive measurement approaches. Similarly, noninvasive optical techniques are hampered by low-transmission, large-density gradients, and high-thermal, spontaneous emission in hot, fast, particle-laden flows. An innovative sensor system is desired for measurements in high-temperature and high-velocity exhaust plumes. Extending existing measurement technologies to full-scale engines requires improved strategies in sensor survivability, overcoming poor signal-to-noise ratio, and the extreme acoustic and vibratory environment in close proximity to the exhaust plume. Key sensor system parameters should include, but not be limited to the following: 1. Measuring temperature is of primary interest. Additional measurement parameters of interest include pressure, velocity, combustion efficiency, and gas composition. Desired speciation of composition measurements include unburned fuel components, intermediate fuel-cracking products, and final products (CO, CO2, H2O, NO, NO2). 2. Temperature measurement accuracy must be better than +/- 5%. 3. Sensor must provide, spatially-resolved point or line-averaged measurements to a resolution of at least 1 mm or smaller. Two-dimensional maps of measurement parameters are also of interest. 4. Minimum sensor bandwidth must exceed 1 kHz. Increased bandwidth up to 100 kHz is preferred. 5. The operational envelope for the sensor must span temperatures from 500–3,000 K (227–2727 °C). 6. Optical sensors are of interest to provide noninvasive measurements that do not perturb plume characteristics. Optical sensors must be capable of performing measurements in particle-laden, highly emissive flows. 7. Sensor lifetime for high-temperature, high-velocity exhaust plume measurements must exceed 1,000 hr. PHASE I: Develop a concept and determine the feasibility of a sensor system for time-resolved measurements in high-temperature, high-velocity exhaust plumes with the ideal goal of providing greater than 1 kHz measurement bandwidth. Ensure that the concept sensor provides point- or line-averaged measurements of temperature over the range of 500 to 3,000 K (227–2727 °C). Additional measurement parameters—including pressure, velocity, combustion efficiency, and composition—are of interest, but not required, in Phase I. Noninvasive optical measurement approaches are desirable, but must be able to operate in flows with high-particulate loads (low transmission) and high emission. Phase I should include (a) benchtop testing and validation of sensor concept and accuracy in controlled high-temperature gas environment, (b) designs for construction of field-deployable sensor prototype, and (c) detailed prototype plans to be developed under Phase II. PHASE II: Develop, demonstrate, and validate a prototype sensor. Improve upon the performance, reliability, and usability of the sensor. Perform field demonstrations, which will guide sensor improvements. Desired improvements include (a) measurement bandwidth in excess of 10 kHz, (b) temperature measurement accuracy better than +/- 5%, (c) measurements at multiple locations within a plume, including close proximity to the nozzle exhaust, and (d) increased capability to handle all relevant engine operating conditions. Include the extension of the sensor prototype to include additional measurement parameters such as pressure, velocity, combustion efficiency, and/or composition. Include (a) revision of the sensor design to improve performance, reliability, and usability; (b) successful demonstration of temperature measurements using the second-generation prototype in high-temperature/velocity exhaust plume; (c) successful demonstration of additional measurement parameters using the second-generation prototype in high-temperature, high-velocity exhaust plume; and (d) delivery and initial testing of the sensor prototype. PHASE III DUAL USE APPLICATIONS: Complete final testing and transition the technology for Navy use. Accurate time-resolved measurements of aircraft engine, rocket, and other plumes could steer development of commercial propulsion systems and modeling tools used in their development. REFERENCES: 1. Peng, W. Y., Cassady, S., Strand, C. L., Goldenstein, C. S., Spearrin, R. M., Brophy, C. M., Jeffries, J. B., & Hanson, R. K. (2019). Single-ended mid-infrared laser-absorption sensor for time-resolved measurements of water concentration and temperature within the annulus of a rotating detonation engine. Proceedings of the Combustion Institute, 37(2) 1435-1443. Elsevier. https://doi.org/10.1016/j.proci.2018.05.021 2. Goldenstein, C. S., Spearrin, R. M., Jeffries, J. B., & Hanson, R. K. (2017). Infrared laser-absorption sensing for combustion gases. Progress in Energy Combustion Science, 60, 132-176. https://doi.org/10.1016/j.pecs.2016.12.002 3. Goldenstein, C. S., Almodovar, C. A., Jeffries, J. B., Hanson, R. K., & Brophy, C. M. (2014). High-bandwidth scanned-wavelength-modulation spectroscopy sensors for temperature and H2O in a rotating detonation engine. Measurement Science and Technology, 25(10), 105104. https://doi.org/10.1088/0957-0233/25/10/105104 4. Sun, K., Sur, R., Chao, X., Jeffries, J. B., Hanson, R. K., Pummill, R. J., & Whitty, K. J. (2013). TDL absorption sensors for gas temperature and concentrations in a high-pressure entrained-flow coal gasifier. Proceedings of the Combustion Institute, 34(2), 3593-3601. https://doi.org/10.1016/j.proci.2012.05.018 5. Hanson, R. K. (2011). Applications of quantitative laser sensors to kinetics, propulsion and practical energy systems. Proceedings of the Combustion Institute, 33(1), 1-40. https://doi.org/10.1016/j.proci.2010.09.007 6. Schäfer, K., Heland, J., Lister, D. H., Wilson, C. W., Howes, R. J., Falk, R. S., Lindermeir, E., Birk, M., Wagner, G., Haschberger, P., Bernard, M., Legras, O., Wiesen, P., Kurtenbach, R., Brockmann, K. J., Kriesche, V., Hilton, M., Bishop, G., Clarke, R., … Vally, J. (2000). Nonintrusive optical measurements of aircraft engine exhaust emissions and comparison with standard intrusive techniques. Applied Optics, 39(3), 441-455. https://doi.org/10.1364/AO.39.000441 7. Ihme, M., 2017. Combustion and engine-core noise. Annual Review of Fluid Mechanics, 49, pp.277-310. https://www.annualreviews.org/doi/pdf/10.1146/annurev-fluid-122414-034542 8. Brès Guillaume A. and Lele Sanjiva K. 2019. Modelling of jet noise: a perspective from large-eddy simulations. Phil. Trans. R. Soc. A. http://doi.org/10.1098/rsta.2019.0081 9. Cavalieri, A. V. G., Jordan, P., and Lesshafft, L. (March 13, 2019). "Wave-Packet Models for Jet Dynamics and Sound Radiation." ASME. Appl. Mech. Rev. March 2019; 71(2): 020802. https://doi.org/10.1115/1.4042736 KEYWORDS: High Temperature Sensor; Temperature Measurement; Time-Resolved; Plume Measurements; Combustion Measurements; Gas Composition Measurement

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Computing and Software; Advanced Materials OBJECTIVE: Develop simulation models and visualization tools for microwave curing process of carbon fiber reinforced composites, and demonstrate the feasibility to manufacture high quality carbon fiber reinforced composites using microwave radiation. DESCRIPTION: Autoclaves are widely utilized to process and manufacture high-performance aircraft composite materials. This conventional method provides laminate consolidation by application of elevated pressures and temperatures; however, the high costs and extensive process times associated with this technique have generated an interest in the implementation of out of autoclave curing methods. Microwave curing is gaining increasing attention as an alternative tool for composite industrialization, due to its potential for reduced cure times, low energy consumption, and mass production. Microwave systems heat materials via electromagnetic field interaction. Electromagnetic fields are transferred to the material, and heat is generated through polarization. Microwave curing has been used for glass fiber composite processing, but there are significant challenges associated with microwave curing of carbon fiber composites. Efficient heating is difficult due to high dielectric loss and low depth of penetration associated with carbon fibers. Another major challenge is related to arcing of carbon fibers, which can result in very high-localized hot spots that damage the surrounding material. Laminate quality is highly dependent on the uniformity of the electromagnetic field in the material. The anisotropic dielectric properties of composite constituents disrupts the intended homogeneous volumetric cure, resulting in non-uniform heating. This heating behavior requires further investigation; highlighting the need for a tool that can model this phenomenon. This STTR topic seeks to develop a multi-physics based model that simulates and optimizes the microwave curing process of thick fiber reinforced composites (up to 10 mm). The model should account for the interaction of electromagnetic, thermal, and chemical mechanisms induced during the curing process. The tool will be used to model aerospace-grade thermoset composite materials (such as IM7/8552) of varying lay-up thicknesses and fiber orientations, to predict curing behavior and material properties. The model predictions for microwave cured fiber reinforced composites will be validated by qualitative (such as porosity, defects, etc.), mechanical (such as tension, flexure, impact, etc.) and chemical (such as differential scanning calorimetry, dynamic mechanical analysis, etc.) coupon testing. The implementation of a microwave curing process would result in reduced cure times and reduced energy consumptions. The modeling tool would aid in the reduction of test runs required for composite part production. It would also give companies greater production scheduling freedom through process modeling of components. This would make production more adaptive and save scheduling time and costs. PHASE I: Develop a modeling methodology based on the proposed concept of a multi-physics tool that can simulate and optimize the microwave curing process of fiber reinforced composite materials. Demonstrate feasibility of the methodology and investigate the effects of the microwave curing conditions, such as power, duration, composite orientation, composite thickness, etc., via simulations, that account for electromagnetic, thermal, and chemical mechanisms on the mechanical properties of the cured composite. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Develop the proposed multi-physics tool to address microwave manufacturing of fiber reinforced composites of thicknesses up to 10 mm. Demonstrate and validate the tool by comparing simulation predictions to the results of various qualitative, mechanical, and chemical tests of microwaved and autoclaved cured fiber reinforced composite coupons. PHASE III DUAL USE APPLICATIONS: Enhance and demonstrate this tool with difficult to process parts, associated with autoclave curing, and with different material systems. Coordinate with the prime and sub-contractors producing composite parts to facilitate the transition and utilization of this tool. The product outcome of this topic has extensive applications for companies producing fiber- reinforced composite parts, in particular companies that utilize an autoclave process. This topic desires to provide a modeling tool to optimize the alternative microwave curing process for the production of quality parts at a lower cost (50% reduction) and quicker turnaround times (40% reduction). REFERENCES: 1. Mishra, R. R., & Sharma, A. K. (2016). Microwave–material interaction phenomena: heating mechanisms, challenges and opportunities in material processing. Composites Part A: Applied Science and Manufacturing, 81, 78-97. https://doi.org/10.1016/j.compositesa.2015.10.035 2. Mgbemena, C. O., Li, D., Lin, M. -F., Liddel, P. D., Katnam, K. B., Thakur, V. K., & Nezhad, H. Y. (2018). Accelerated microwave curing of fibre-reinforced thermoset polymer composites for structural applications: A review of scientific challenges. Composites Part A: Applied Science and Manufacturing, 115, 88-103. https://doi.org/10.1016/j.compositesa.2018.09.012 3. Galos, J. (2021). Microwave processing of carbon fibre polymer composites: a review. Polymers and Polymer Composites, 29(3), 151-162. https://doi.org/10.1177/0967391120903894 KEYWORDS: Microwave curing; Manufacturing process; Physics-based modeling; Carbon fiber thermoset composites; Process optimization; Mechanical testing

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Integrated Sensing and Cyber; Advanced Materials OBJECTIVE: Develop ultra-compact, lightweight Mid-wave infrared (MWIR) zoom imaging optics based on flat lens technology and with 7 times improvement in SWaP. DESCRIPTION: MWIR imaging systems are essential to intelligence, surveillance, and reconnaissance (ISR) missions. Conventional IR optics are thick, heavy, costly, and often require bulky mechanical mounting system to keep their multiple optical elements stable and well-aligned. Current systems weigh 400 g or more, often necessitating heavy-duty gimbals for aiming. Heavy optics require tens of minutes to reach thermal equilibrium during takeoff and landing of air platforms such as unmanned aircraft systems (UASs), limiting ISR operations. Flat lens technologies have the potential to provide extremely compact and lightweight imaging capability in the MWIR, including reduced costs and added functionality such as zoom or variable focus [Refs 1 & 2]. Microfabricated flat lens optics can be only 1 mm thick or less, reducing overall lens system length and supporting more compact imaging systems. Their extremely low mass allows them to reach thermal equilibrium in less than one minute in typical airborne scenarios. Two promising flat lens technologies are metasurface optics (or meta-optics) [Refs 3–5], and multilevel diffractive lenses (MLD) [Ref 6]. Both have challenges related to scalable fabrication and with chromatic aberration for broadband applications. The MLD approach has challenges associated with large numerical apertures (small f-numbers) and high throughput, especially for oblique angles of incidence, which gives rise to significant vignetting, that is, reduction of the image's brightness toward the sensor periphery compared to center. Meta-optics can achieve extremely low-aberration imaging, often reducing the number of optical elements required. As the design space and device function complexity of flat lenses scales up, limitations of the conventional human-driven forward design of meta-optics have necessitated a breakthrough in design philosophy. Recent work using inverse design with appropriate artificial intelligence (AI) tools positions this method to transform meta-optics design [Refs 7–9]. The inverse design approach explores the physics of nanophotonics using advanced mathematical tools, iterating until an optimal solution is achieved. Inverse design has significant advantages over conventional forward design: it does not need a priori knowledge of physics; it can be used for complex designs that have no analytical solution; and it can automatically balance the trade-offs among multiple device functions given the design constraints while minimizing crosstalk. Design robustness can also be considered using the inverse design techniques. The development of a novel lightweight, low-aberration flat lens-based MWIR zoom optics must achieve certain minimum specifications in performance and size, weight, and power (SWaP) to accelerate its adoption for next-generation ISR missions. For example, the aperture size and f/# must be large enough to be useful for low-light imaging. For this effort, the target specifications include, but are not limited to, the follows: (a) total weight, including housing, mount, and motorized control: 100 g or less (b) axial length of lens elements: 2 cm or less (i.e., > 7 times improvement over conventional zoom lens), (c) focal length range: f/2 for wide field of view (FoV), variable up to f/8 for narrow FoV, (d) clear aperture: 2 cm or more, with a scalable fabrication process that can achieve larger sizes, (e) spot size: within 20% of diffraction limit, (f) in-band transmittance: 85% or better, including for all incident angles up to ±25°, (g) electro-mechanical zoom time: 3s or less, and zoom range up to 5X. The goal is to dramatically reduce size and weight versus comparable state-of-the-art conventional zoom lens systems, without reducing performance. Weight will be reduced to 25% or less, and axial length of the optical elements (excluding back focal length standoff distance) will be reduced to 15% or less than that of the conventional zoom lens set-up. The reduced weight and length should reduce time required for zoom adjustments. Initially, focal length tuning can be performed manually, but tuning speed should achieve the above target specification by the end of this effort. Longer-term goals include reduction of f/# (the f number which is a measure of the FoV of the lens set up) and increase in mechanical robustness to withstand vibrations, acceleration forces, and mechanical shocks associated with unmanned aerial system (UAS) takeoff and landing. PHASE I: Determine the feasibility of, detail, model, and simulate an innovative approach for an ultra-compact lightweight, MWIR zoom imaging optic based on flat lens technology. Design, fabricate, and test in the laboratory a proof of concept to demonstrate the flat lens technology and its varifocal capability. Characterize performance based on the specifications outlined in the topic description. The proof of concept should have a clear aperture diameter of at least 4 mm, a zoom range of 5x, a wide FoV of f/2, in-band transmittance of 60% or better, and 96% polarization insensitivity. Design a compact MWIR zoom imaging optic to be fabricated and tested in Phase II. Use modeling and simulation to estimate its performance, including size, weight, and power. Develop a test plan and test procedures to be developed in Phase II. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Optimize the design of the prototype flat lens MWIR zoom optic based on the design from Phase I. Develop modifications that can improve performance and perform modeling and simulations. Design electro-mechanical lens housing and motorized control software for the zoom system. Fabricate the zoom optic and test it in the laboratory to demonstrate all the performance specification targets listed in the Description. Detail a scalable fabrication process that provides a roadmap toward cost-effective production and larger clear aperture systems. Study numerically the trade-offs of zoom optic performance between aperture size, numerical aperture (f/#), working bandwidth, transmittance, and FoV. Also investigate theoretically and experimentally the feasibility of extending the zoom range from 5X to 10X. PHASE III DUAL USE APPLICATIONS: Transition the technology for U.S. Government use. Fully develop and transition the technology and methodology based on the research and development results developed for DoD applications in the various areas of anomaly detection, surveillance, and reconnaissance applications. The commercial sector can also benefit from this innovative flat lens with very low SWaP in the areas of detection of toxic gases, environmental monitoring, and noninvasive structural materials monitoring and sensing. REFERENCES: 1. Chen, W. T., Zhu, A. Y., Sanjeev, V., Khorasaninejad, M., Shi, Z., Lee, E., & Capasso, F. (2018). A broadband achromatic metalens for focusing and imaging in the visible. Nature nanotechnology, 13(3), 220-226. https://doi.org/10.1038/s41565-017-0034-6 2. Bosch, M., Shcherbakov, M. R., Won, K., Lee, H. S., Kim, Y., & Shvets, G. (2021). Electrically actuated varifocal lens based on liquid-crystal-embedded dielectric metasurfaces. Nano Letters, 21(9), 3849-3856. https://doi.org/10.1021/acs.nanolett.1c00356 3. Cotrufo, M., Guo, S., Overvig, A., & Alù, A. (2021, March). Nanostructured metasurfaces for optical wavefront manipulation. In Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XIV (Vol. 11696, p. 1169609). International Society for Optics and Photonics. https://doi.org/10.1117/12.2584024 4. Presutti, F., & Monticone, F. (2020). Focusing on bandwidth: achromatic metalens limits. Optica, 7(6), 624-631. https://doi.org/10.1364/OPTICA.389404 5. Banerji, S., Meem, M., Majumder, A., Vasquez, F. G., Sensale-Rodriguez, B., & Menon, R. (2019). Imaging with flat optics: metalenses or diffractive lenses?. Optica, 6(6), 805-810. https://doi.org/10.1364/OPTICA.6.000805 6. Molesky, S., Lin, Z., Piggott, A. Y., Jin, W., Vuckovic, J., & Rodriguez, A. W. (2018). Inverse design in nanophotonics. Nature Photonics, 12(11), 659-670. https://doi.org/10.1038/s41566-018-0246-9 7. Li, Z., Lin, P., Huang, Y. W., Park, J. S., Chen, W. T., Shi, Z., Qui, C. –W., Cheng, J. –X., & Capasso, F. (2021). Meta-optics achieves RGB-achromatic focusing for virtual reality. Science Advances, 7(5), eabe4458. https://doi.org/10.1126/sciadv.abe4458 8. Shi, Z., Zhu, A. Y., Li, Z., Huang, Y. W., Chen, W. T., Qiu, C. W., & Capasso, F. (2020). Continuous angle-tunable birefringence with freeform metasurfaces for arbitrary polarization conversion. Science Advances, 6(23), eaba3367. https://doi.org/10.1126/sciadv.aba3367 KEYWORDS: Low-aberration; Imaging optics; Flat lens; Zoom capabilities; Mid-wave infrared; MWIR; Metamaterials

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy; Microelectronics; Directed Energy OBJECTIVE: Develop novel ultra-fast simulation technology capable of speeding up full-wave electrodynamic simulation by 1,000 times. This ultra-fast simulation technology will be used to develop long-wave infrared (LWIR) lens that are 100 times thinner and lighter than today’s state-of-the-art LWIR optics and with fully customizable aperture sizes and focal length. DESCRIPTION: Flat metamaterial optical devices provide a unique opportunity for producing compact and high-performance components for manipulation of light [Ref 1]. Such devices may be constructed through nanofabrication on a planar substrate, providing the possibility of replacing traditional diffractive components that are versatile for various defense and civilian applications [Ref 2]. Flat optics is particularly interesting in the long-wave infrared region because the lack of high-quality imaging optics. Traditional lenses are costly and bulky and possess limited aperture size in the infrared region. Developing integrated imaging optics in LWIR is of great interest especially for tactical surveillance and reconnaissance in this special range [Ref 3]. Metamaterial optical device is a 2D array of dielectric structures that is used to focus transmitted light to a single position directly in front of the device. Typically, these structures are emulated by simulating each dielectric unit cell individually to compute a phase and amplitude transmittance for each cell. While this approach makes for an approximation of the overall device performance, it would be useful to be able to simulate the entire device as a whole to capture the complete physical characteristics of the device structure. However, a simulation of this scale requires several hours or days to perform with a conventional CPU-based finite-difference time-domain (FDTD) method. To get around the lack of sufficient computational power and to shorten the computation time, the typical compromising approach is to assume a constant phase and amplitude response from each cell [Ref 4], which are used to approximate electromagnetic fields in front of the device. This approximation leads to undesirably less accurate predictions [Ref 5], resulting in sub-optimal device performance. Various techniques, such as the optimization technique in Ref 6, have been attempted to correct for these errors and yet none have been completely successful. Addressing the very time consuming computation and the accuracy of the modeling and simulation issues simultaneously for this type of complex optics is therefore paramount for designing and fabricating compact optics for LWIR imaging systems with stringent high-performance requirements. This topic seeks to exploit emerging computing hardware to develop ultra-fast computation algorithms to accelerate accurate simulation and uncompromising optimization of flat optics in the LWIR wavelength range. This topic seeks development of FDTD simulation that is at least 1,000 times faster than today’s open source and commercially available FDTD solutions. The developed ultra-high-speed FDTD solution is then utilized to model and simulate metalenses that reduce the computation time—by up to 1,000 times—relative to conventional FDTD methods [Ref 8]. The simulation solution should be able to simulate metalenses of multiple centimeters in optical aperture with optimization of imaging figures of merit such as focusing efficiency and Strehl ratio with respect to the unit cell design parameters. The metalens’ focusing efficiency should be higher than 95% over a broad wavelength range from 8–12 microns, and at least 100 times lighter and thinner than traditional state-of-the-art LWIR imaging optics [Ref 8]. Traditional FDTD [Ref 7] would take tens of hours to simulate the abovementioned structure. With the successful development of this algorithm, the same simulation should finish in about one minute. PHASE I: Determine optimal hardware platform and computational resources required for centimeter-scale simulation of metamaterial lens. Identify both the starting device design based on material and geometry designs from previous experimental works, as well as the figures of merit to optimize and measure experimentally. Demonstrate feasibility and begin development of a working prototype of the software, to include demonstration of a near field calculation of 5 cm x 5 cm flat optics system with a simulation speed improvement of over 1,000 times when compared to CPU-based FDTD. Show consistency between these simulations and experimental demonstrations of the flat metamaterial optics in LWIR. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Develop, demonstrate, and validate the prototype. Incorporate adjoint-based optimization capabilities into the solver. Using adjoint-enabled gradient-based optimization, produce a prototype structure that maximizes the focusing efficiency over the spectral wavelength of interest using about 100 iterations. Demonstrate a significant improvement in device performance that surpasses that of conventional LWIR imaging systems. PHASE III DUAL USE APPLICATIONS: Transition the technology for Government use. Further develop and refine the design of the simulation software and assist in adapting the simulation software for optimization designs of various photonic devices. The commercial sectors such as the optics and camera industries can benefit from the reduction of the individual simulation time from several hours to seconds, meaning more parameters can be scanned and at greater resolution, allowing one to simulate structures at a larger scale, enabling full 3D modeling and simulation of an entire device instead of components, and running many jobs simultaneously in the cloud. REFERENCES: 1. Yu, N., & Capasso, F. (2014). Flat optics with designer metasurfaces. Nature materials, 13(2), 139-150. https://doi.org/10.1038/nmat3839 2. Khorasaninejad, M., & Capasso, F. (2017). Metalenses: Versatile multifunctional photonic components. Science, 358(6367). https://doi.org/10.1126/science.aam8100 3. Zuo, H., Choi, D. -Y., Gai, X., Ma, P., Xu, L., Neshev, D. N., Zhang, B., & Luther-Davies, B. (2017). High-efficiency all-dielectric metalenses for mid-infrared imaging. Advanced Optical Materials, 5(23), 1700585. https://doi.org/10.1102/adom.201800585 4. Shrestha, S., Overvig, A. C., Lu, M., Stein, A., & Yu, N. (2018). Broadband achromatic dielectric metalenses. Light: Science & Applications, 7(1), 1-11. https://doi.org/10.1038/s41377-018-0078-x 5. Chung, H., & Miller, O. D. (2020). High-NA achromatic metalenses by inverse design. Optics express, 28(5), 6945-6965. https://doi.org/10.1364/OE.385440 6. Lin, Z., & Johnson, S. G. (2019). Overlapping domains for topology optimization of large-area metasurfaces. Optics express, 27(22), 32445-32453. https://www.osapublishing.org/DirectPDFAccess/58EECB62-F0FB-4B4F-89A74FA8011960D9_422568/oe-27-22-32445.pdf?da=1&id=422568&seq=0&mobile=no 7. Warren, C., Giannopoulos, A., Gray, A., Giannakis, I., Patterson, A., Wetter, L., & Hamrah, A. (2019). A CUDA-based GPU engine for gprMax: Open source FDTD electromagnetic simulation software. Computer Physics Communications, 237, 208-218. https://doi.org/10.1016/j.cpc.2018.11.007 8. Hughes, T. W., Minkov, M., Williamson, I. A., & Fan, S. (2018). Adjoint method and inverse design for nonlinear nanophotonic devices. ACS Photonics, 5(12), 4781-4787. https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.8b01522# KEYWORDS: Full-wave photonic simulation; Design optimization; Computational speed improvement; Metalens; Metamaterials; Lens

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy; Integrated Sensing and Cyber OBJECTIVE: Develop capability that leverages artificial intelligence and machine learning (AI/ML) technologies to debloat tactical software to reduce support costs, improve run-time stability, and reduce cybersecurity vulnerability. DESCRIPTION: Much modern software suffers from “bloat” that negatively impacts its maintenance costs, performance, and security. Commercial software tries to address wide audiences and focuses on programmer productivity, resulting in software with many indirections, libraries, and layers of abstraction. Government entities have not historically incentivized industry to produce minimal code bases, sometimes even basing funding on the number of source lines of code (SLOCs). Compounding this state of affairs, Naval Control Systems (NCSs) are built and upgraded over extended periods of time, resulting in systems containing tens of millions of SLOCs. Exploratory research at the Naval Undersea Warfare Center has determined that significant bloat can be removed from these complex control systems. One impact of this bloat is cost associated with supporting excessive binary executable sizes. A more troubling consequence of software bloat is instability in the run-time tactical system. The presence of exploitable attack surfaces in the bloat within code is a third problem. Finally, excessive bloat has a commensurate impact on cost and time to perform system testing. As testing rarely exercises the total system, excessive SLOCs and binary executable sizes increase the likelihood of “escaped bugs,” software problems that are not seen until after system fielding. Escaped bugs require heroic measures to fix. State-of-the-art research studies by subject matter experts in academia outline the approaches that can be taken to de-bloat and harden software systems. Yet there are few, if any, commercial programs to automatically de-bloat and harden software systems, due to commercial emphasis on productivity and software reuse. The Naval Undersea Warfare Center (NUWC) has experimented with debloating tactical code, demonstrating the utility of such an effort. However, the exploratory debloating process conducted by NUWC was labor-intensive and tailored, making this sort of debloating cumbersome and unaffordable in the context of envisioned Continuous Integration/Continuous Delivery (CICD) capability fielding. The NUWC manual-intensive process seems amenable to being automated by use of AI/ML. Based on NUWC’s success, the Navy seeks a solution to develop a generalizable tactical software debloating capability informed by AI/ML. There are multiple metrics for software debloating. The first metric is the number of SLOCs reduced or decreased in binary file size, as there can be some benefit to sheer reduction in the total system size. However, it has been shown that this quantity is misleading because debloat tools that perform hardening are often expected to increase the overall file sizes by including additional protections for cyber-resiliency. The second metric is the quality of bloat removal, where the bloat that has been removed substantially improves system stability and reduces cybersecurity vulnerabilities. For example, past research has used as a metric “code reuse gadget count reduction”, which measures the difficulty for an attacker to mount a gadget-based code reuse exploit such as return-oriented programming (ROP). However, realistic debloating scenarios have shown that even high gadget count reduction rates can fail to limit an attacker’s ability to construct an exploit and may even introduce new quality gadgets [Ref 2]. Thus, the quality of debloat metric should use “functional gadget set expressivity” and “special purpose gadget availability” to assess the utility of the gadgets available to the attacker rather than the quantity, as calculated using the Gadget Set Analyzer (GSA). The technology sought would have a threshold requirement of decreased functional gadget set expressivity and special purpose gadget availability by 10% relative to the untouched tactical system. The security metrics would identify the reduction in unique attack surfaces associated with bloat. Finally, the performance metric would characterize the improved performance associated with debloating as a modification to tactical computational time and memory usage. Similar metrics are expected to be derived for container, Linux kernel, and firmware debloat. PHASE I: Develop a concept for a generalizable debloating capability powered by AI/ML. The concept must demonstrate feasibility to reduce the bloats in code, with potential to reduce attack surfaces and improve software quality according to the parameters in the Description. Feasibility will be demonstrated through analysis and modeling. The Phase I effort can be demonstrated on unclassified software the company feels is analogous to the complexity level of the target USW systems. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II. PHASE II: Develop and deliver a prototype generalizable debloating capability powered by AI/ML for testing and evaluation based on the results of Phase I. Demonstrate that the prototype meets the parameters in the Description. The technology will be assessed over the course of Phase II by Navy software subject matter experts (SMEs) knowledgeable about the investigative effort to debloat Navy software. PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to Navy use. The final product will consist of a capability to debloat tactical software that leverages AI/ML to minimize the tailoring and labor that can be associated with a manual debloating approach. The resultant technology will be used during system integration and production by the prime contractors producing Undersea Warfare Systems such as AN/SQQ-89A(V)15 and AN/UYQ-100. The generalized technology developed could also be used for debloating any complex software system, such as information technology systems, and critical infrastructure systems such as power generation, water purification, and healthcare delivery. REFERENCES: 1. Alhanahnah, M., Jain, R., Rastogi, V., Jha, S., & Reps, T. (2021). Lightweight, Multi-Stage, Compiler-Assisted Application Specialization. arXiv preprint arXiv:2109.02775. Online: https://doi.org/10.48550/arXiv.2109.02775 2. Brown, Michael D. and Santosh Pande. “Is Less Really More? Towards Better Metrics for Measuring Security Improvements Realized Through Software Debloating.” arXiv:1902.10880v3. https://doi.org/10.48550/arXiv.1902.10880 3. Bruce, B. R., Zhang, T., Arora, J., Xu, G. H., & Kim, M. (2020, November). Jshrink: In-depth investigation into debloating modern java applications. In Proceedings of the 28th ACM Joint Meeting on European Software Engineering Conference and Symposium on the Foundations of Software Engineering (pp. 135-146). Online: https://dl.acm.org/doi/abs/10.1145/3368089.3409738 4. Casinghino, C., Paasch, J.T., Roux, C., Altidor, J., Dixon, M., & Jamner, D. (2019, May 28). Using Binary Analysis Frameworks: The Case for BAP and angr. NASA Formal Methods https://doi.org/10.1007/978-3-030-20652-9_8 5. Christensen, J., Anghel, I. M., Taglang, R., Chiroiu, M., & Sion, R. (2020). DECAF: Automatic, Adaptive De-bloating and Hardening of COTS Firmware. Proceedings of the 29th USENIX Security Symposium (pp. 1713-1730). Virtual: USENIX. doi:978-1-939133-17-5. Online: https://www.usenix.org/conference/usenixsecurity20/presentation/christensen KEYWORDS: Continuous Integration/Continuous Delivery; CICD; source lines of code; SLOCs; software debloating; cybersecurity vulnerabilities; instability in the run-time tactical system; artificial intelligence and machine learning; AI/ML

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Intergated Network Systems-of-Systems OBJECTIVE: Develop a capability to collect, analyze, and predict levels of Tributyltin Oxide (TBTO) in deployed sonar domes. DESCRIPTION: A sonar dome protects the acoustic transducers, to reduce noise and enable optimal sonar performance. Crucial to its function is that the dome does not foul. Historically, this has been done by imbuing sonar domes with Tributyltin Oxide (TBTO) during the manufacturing process. Research to prevent fouling has not developed an alternative that is qualified for the domes on surface combatants. Even when a new anti-fouling method may be identified, there will be scores of sonar domes imbued with TBTO, with decades of remaining service. A combatant is at sea for about eight years before maintenance carried out at dry dock. Conventional, off-the-shelf antifouling approaches do not work with sonar domes, because they are made of rubber. The Naval Research Laboratory (NRL) has recently developed a rapid, non-destructive, and inexpensive method to measure TBTO (or other anti-fouling systems) in sonar domes while a ship is dry docked. This will provide, for the first time, the data necessary for a nuanced understanding of the anti-fouling efficacy, throughout its service life. The Navy seeks technology that will enable central management of these measurements from USN sonar domes that are deployed to locations and environments around the world, together with an ontological framework to record pertinent information about the sonar dome, such as manufacturing details and service life history. It is also desired that the architecture of the proposed technology accommodate a methodology for predicting anti-fouling life and updated algorithms as data supports algorithm refinement. Development of an initial predictive algorithm could fall within the scope of this STTR topic. The Navy seeks a centralized capability for collecting this information, populating an ontological framework with pertinent data (such as sonar dome manufacturing details and service life history) for each measurement, and predicting future TBTO levels to understand both: 1. When sonar domes will need to be replaced due to depletion of TBTO. 2. When it may be appropriate to reduce the amount of TBTO (or future anti-foulant) used in new-construction sonar domes with changes in dome material or anti-foulant. The centralized capability will enable the Navy to minimize maintenance while also minimizing harm to the marine environment. The framework described herein must include: • A method to capture data from a measurement tool for utilization in a Fleet-wide physics-based model designed for modular updating manually via future re-assessment of an updated database. • A graphical user interface (GUI) that displays tracked values of interest. Examples of potential elements to this ontology are: • Measured anti-foulant loading remaining in coating. • Models of TBTO degradation as a function of time and combatant travel profile. • Predicted remaining lifespan of sonar dome TBTO based on measurements and predicted travel profile. • Updated physics-based model calculations. Any additional ontological elements that would improve the model would be welcome. The physics-based model shall also incorporate: 1. Input parameters, including service conditions, that may vary over a deployment. Variables of primary considerations are surface ocean temperature and salinity, but others may be added. 2. Capability to change the input properties, to accommodate updated material specifications and other improvements. PHASE I: Develop a concept for a physics-based database and GUI for diffusion from a sonar dome that meets all the parameters in the Description. Demonstrate the concept is feasible through analysis, simulation, and modelling. Preliminary experimental data will be provided by NRL. The Phase I Option, if exercised, will include the initial design specifications and a capabilities description to build a prototype solution in Phase II. PHASE II: Develop and deliver a prototype physics-based database and GUI for the TBTO collection and prediction capability. Demonstrate the prototype meets the required range of desired performance attributes given in the Description. Feasibility will be demonstrated through system performance with information from initial TBTO measurements that will be collected. Develop a Phase III commercialization plan. PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology for Navy use as software to collate, analyze, and manage TBTO data collected and tested via a hardware measurement capability maintained by IWS 5.0. Demonstrate and report on performance during laboratory testing. This technology can be used in a wide range of products where measurements of toxins or other material dopants of specified loadings are collected and predictions of future state are dependent on numerous variables which are not entirely dependent on one another. With the appropriate modifications, it may be used to monitor performance of commercial antifoulant systems, particularly when a new system is being adopted. The technology would be of greatest use in cases where environmental impact of a substance is of national or global concern, particularly in water / wastewater management or aquaculture REFERENCES: 1. Omae, Iwao. (2003). “Organotin Antifouling Paints and Their Alternatives.” Applied Organometallic Chemistry, Vol. 17, n2 (200302), . 81 - 105. https://www.worldcat.org/title/organotin-antifouling-paints-and-their-alternatives/oclc/4633838388 2. Donnelly, Bradley et al. (2019) “Effects of Various Antifouling Coatings and Fouling on Marine Sonar Performance. Polymers.” Polymers Vol. 11, Issue 4, 663. https://www.mdpi.com/2073-4360/11/4/663 3. "AN/SQQ-89(V) Undersea Warfare / Anti-Submarine Warfare Combat System." United States Navy Fact File, 24 March 2021. https://www.navy.mil/Resources/Fact-Files/Display-FactFiles/Article/2166784/ansqq-89v-undersea-warfare-anti-submarine-warfare-combat-system/ KEYWORDS: Sonar dome; tributyltin oxide; TBTO; anti-fouling for sonar domes; ontological framework; predicting anti-fouling life; water management; wastewater management; aquaculture

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics OBJECTIVE: Develop innovative and affordable wide aperture optics technology for imaging sensors operating in the mid-wave infrared (MWIR) and short-wave infrared (SWIR) bands. DESCRIPTION: Electro-optic and infrared (EO/IR) video imaging sensors (cameras) are widely used for situational awareness, surveillance, and targeting. The Navy is deploying such cameras in multiple spectral bands, covering both wide and narrow fields of view (FOV). Wide field of view (WFOV) cameras are particularly expensive as they employ large focal plane array (FPA) sensors and, to gather sufficient light, these cameras must have large aperture optics (lenses). In the infrared (IR), these lenses are especially costly, not benefitting from large commercial economies of scale as exists for camera lenses in the visible spectrum. Furthermore, because of the shallow depth of field inherent in such large aperture lenses, the optical elements (and the FPA) must be aligned to extremely tight tolerances in order to maintain the high resolution required. Tolerances for axial alignment on the single-micron level are not uncommon. In addition, the optical assembly must be rugged enough for shipboard deployment, maintaining its alignment in spite of operational shock, vibration, and extremes of temperature. Consequently, not only are the optical elements (lens elements) expensive, but the optical housing (lens barrel) is expensive as well. Finally, the precision assembly processes required to achieve such tight optical alignment are labor intensive and the labor is highly skilled in nature. The result is that such cameras are excessively costly. The Navy needs an innovative technology for focusing IR light onto FPA sensors with high optical resolution. The goal is to dramatically reduce cost without compromising performance. A nominal cost reduction of 5:1 is desired for the optical assembly (based on the current state-of-the-art for conventional optics), which, for this purpose, does not include the material cost of the FPA but does include the optical elements, the optical assembly, and alignment of the optics with the FPA. A solution applicable to both the MWIR and the SWIR is desired. However, the technology may be demonstrated in either band, at the discretion of the proposer. A maximum effective aperture of f1.0 is desired with a 90° FOV and coverage sufficient for a 2k X 2k pixel FPA with 10 µm pitch. The light fall-off from FPA center to the corner of the FPA shall not exceed a factor of 2.0. The depth of field shall be sufficient to resolve single pixel targets. Note that all requirements apply at full aperture. Optical aberrations are acceptable provided they can be compensated for in post processing and provided that they are not so severe as to inhibit resolution of a single pixel target lying anywhere in the imaged field. In demonstrating a solution, and in order to reduce cost, a large format FPA meeting the dimensions given above need not be included in the prototype. A smaller FPA (or multiple FPAs) may be used provided it can be shown that the required image quality defined above is achieved over the extent of the large format FPA. This effort anticipates a hardware solution for a single large format FPA that yields high image quality (resolution, dynamic range, noise, etc.) video capture in real time. Image capture shall accommodate a video frame rate of 30 frames per second. Solutions that attempt to re-construct images or combine images from multiple FPAs are undesirable. Predominantly software-based solutions – that is solutions based on extensive post processing of the captured image data will not be considered. Solutions incorporating electro-mechanical compensation of optical elements are permitted providing the compensation mechanism does not reduce the integration time available to the FPA. Any electro-mechanical components included in the solution must also be shown to have a (maintenance-free) life expectancy comparable to the FPA. At the end of the effort the prototype shall be delivered to Naval Surface Warfare Center (NSWC) Crane Division. Included in the prototype will be the FPA (or FPAs) used to demonstrate the image quality obtained by the solution, and any controllers, power supplies, housings, coolers, output interfaces, special processing hardware, custom software, fixtures, and specialized tools necessary to replicate testing of the prototype. A cost estimate for production and integration of the solution will be performed to assess the reduction in cost associated with the technology. The cost assessment shall be benchmarked to the cost of a conventional optical design. PHASE I: Develop a concept for a large aperture optical system that meets the objectives stated in the Description. Demonstrate the feasibility of the concept in meeting the Navy’s need. Analyze the effect on image quality and predict the benefits for cost reduction. Feasibility shall be demonstrated by a combination of analysis, modeling, and simulation. The Phase I Option, if exercised, will include an initial sensor specification, test specification, and capabilities description necessary to build and evaluate prototype hardware in Phase II. PHASE II: Develop and demonstrate a prototype large aperture optical system for imaging IR sensors based on the concept, analysis, preliminary design, and specifications resulting from Phase I. Demonstration of the large aperture optics technology shall be accomplished through test of a prototype in a laboratory or sheltered outdoor environment. At the conclusion of Phase II, prototype hardware shall be delivered to NSWC Crane along with complete test data, installation and operation instructions, and any auxiliary software and special hardware necessary to operate the prototype. PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology for Government use. Develop specific optical designs for Navy sensor systems. Establish hardware configuration baselines, produce support documentation, production processes, and assist the Government in the integration of the optical technology into existing and future WFOV imaging sensor systems. The technology resulting from this effort is anticipated to have broad military application. In addition, there are law enforcement and security applications. Scientific applications include satellite and aerial imagery. REFERENCES: 1. Driggers, Ronald G., et al. Introduction to Infrared and Electro-Optical Systems, Second Edition. Boston: Artech House, 2012. 2. Gibson, Daniel, et al. "Diffusion-based gradient index optics for infrared imaging.” Optical Engineering 59 (2020): 112604-1-22. https://www.spiedigitallibrary.org/journals/optical-engineering/volume-59/issue-11/112604/Diffusion-based-gradient-index-optics-for-infrared-imaging/10.1117/1.OE.59.11.112604.full?SSO=1 KEYWORDS: Video Imaging; Imaging Sensors; Wide Field of View Cameras; FOV; Large Aperture Optics; Depth of Field; Optical Resolution

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Directed Energy (DE) OBJECTIVE: Develop a periscope imaging, electronic warfare, and High Energy Laser (HEL) beam propagation model over the marine aerosol boundary layer for the integration of propagation modeling software into a system that will investigate absorption and scattering properties of marine aerosols, the interplay between aerosols and turbulence, and the impact on imaging and electronic warfare (EW). DESCRIPTION: The Navy seeks technologies that are oriented toward a deeper experimental and theoretical understanding of maritime turbulence and laser beam propagation in the marine boundary layer (MABL). Ocean evaporation is occurring within a very thin molecular layer at the surface. However, there are indications that instantaneous turbulent structures in the ocean and marine atmospheric mixing layers play a critical role in determining the water vapor flux and near surface particulate (aerosol) concentrations. The Navy is looking for a greater understanding of the marine aerosols and their impact on turbulence on periscope imaging, EW, and HEL beam propagation. Aerosol properties will be studied using available instruments such as particle counters, sun photometers, Short Wave Infrared (SWIR) cameras, Delayed Tilt Anisoplanatism (DELTA) camera, RAMAN scattering instrument, and instruments for aerosol absorption quantification. This proposed study will help improve the current atmospheric models for submarine imaging/ EW and HEL horizontal beam propagation within the MABL. Recent efforts have been aimed at characterizing the turbulence in the marine wave layer and surface layer marine boundary layer. The aerosol and turbulence models developed through experimental measurements will be used to model nonlinear effects such as thermal blooming in a marine environment on both continuous and pulsed lasers. Additionally, image contrast reduction due to marine aerosols will be studied and the prospect of determining aerosol loading from degraded images will be investigated. In this proposed study and model, we are looking for an innovative instrument development to understand the nonlinearity of the atmosphere like thermal blooming and RAMAN scattering. The model developed shall include atmospheric nonlinearity and its effects on a complete model of Imaging and HEL beam propagation that includes turbulence and aerosol effects. The model will be extremely useful for development of adaptive optics and beam control systems to maximize power in the bucket in case of horizontal propagations. In this STTR topic the proposer shall explore the use of a small Unmanned Aircraft System (sUAS) and develop and execute sUAS flight profiles for marine Sea-Air turbulence and aerosol interface research. Marine boundary layer profiling at different heights shall be used to enhance the multi-target capability of a customer’s imaging and on HEL as well as the HEL subsystem’s including laser range finders (LRFs), and beacon and tracker illuminator lasers. Additionally, such profiling in combination with radiative transfer and Imaging and HEL propagation models such as the Laser Environmental Effects Definition and Reference (LEEDR) and High Energy Laser End to End Operational Simulation (HELEEOS) codes shall enhance post-engagement HEL forensic analysis such as target effects in the marine boundary layer. Current measurement techniques, such as Laser Doppler Velocimetry (LDV), are limited to resolutions of 0.5 meters or greater and fall short of the required millimeter level resolution. A new type of spectral imaging modality and instrumentation is required that will increase our understanding of ocean evaporation and lead to better tools for measuring and modeling the near-marine boundary layer for optical and radio frequency Naval applications. This generalized understanding will significantly enhance beam optic directors, adaptive optics, and other turbulence mitigating techniques to enhance the reach and effectiveness of communication as well as defensive and offensive high energy laser engagement in the marine aerosol boundary layer. PHASE I: Provide a concept to solve the Navy’s problem, and demonstrate the feasibility of that concept. Develop the general model concept and instrumentation setup over MABL to collect data for the prediction atmospheric non linearity and its effects such as marine thermal blooming and other marine non linear effects due to image degradation and HEL horizontal beam propagation through the MABL < 60 ft above marine surface. Develop clear model concepts and non-linear MABL data acquisition setup to remotely measure temperature, pressure, and marine aerosol for the acquisition MABL model validation and verification. Phase I Option, if exercised, will include the initial model and capabilities description to build a prototype model and validation of the proposed model by data collection over marine surface in Phase II. PHASE II: Develop the marine aerosol on image degradation and HEL Beam propagation model and data collection analysis software which shall be delivered to Navy. The MABL model shall be used for submarine imaging system and target detection and tracking, HEL target lethality improvement and integration with submarine HEL beam control software for evaluating HEL horizontal beam propagation and image degradation through marine aerosol environment. The model shall be used for system performance evaluation based on the results of Phase I concepts. Describe how evaluation can be accomplished through modeling or non-linear analytical methods to demonstrate that the technology does have the potential to meet Navy imaging, such as image degradation, target detection, target identification, and HEL performance goals such as remotely profile horizontal turbulence profile mapping, temperature, and pressure profile mapping. PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to Navy submarine platforms as a metrological tool for marine wave boundary data collection. The non-liner marine aerosol effects on Submarine Imaging and HEL beam propagation model and innovative data analysis technology such as Fourier Optical analysis have both commercial and DoD applications. This technology can improve a commercial ship’s localized weather prediction and update the weather software for safe operation. Additionally, improved LIDAR detection for range at day, night, and all-weather conditions is beneficial for both commercial and DoD applications. The nonlinear marine aerosol metrology model system could also find applications in trace gas and pollution monitoring. REFERENCES: 1. Wasiczko Thomas, Linda M., Moore, Christopher I., Burris, Harris R., Suite, Michele, Smith Jr., Walter Reed, and Rabinovich, William. “NRL's Research at the Lasercomm Test Facility: Characterization of the Maritime Atmosphere and Initial Results in Analog AM Lasercomm”, Proc. SPIE, 6951, Atmospheric Propagation V, 69510S (April 18, 2008). https://doi.org/10.1117/12.783791 2. David N. Whiteman, "Examination of the traditional RAMAN lidar technique. I. Evaluating the temperature-dependent lidar equations," Appl. Opt. 42, 2571-2592 (2003) https://doi.org/10.1364/AO.42.002571 3. David N. Whiteman, "Examination of the traditional RAMAN lidar technique. II. Evaluating the ratios for water vapor and aerosols," Appl. Opt. 42, 2593-2608 (2003) https://doi.org/10.1364/AO.42.002593 4. Chunhua Deng , Sarah D. Brooks , German Vidaurre & Daniel C. O. Thornton (2014) Using RAMAN Microspectroscopy to Determine Chemical Composition and Mixing State of Airborne Marine Aerosols over the Pacific Ocean, Aerosol Science and Technology, 48:2, 193-206, DOI: 10.1080/02786826.2013.867297 https://www.tandfonline.com/doi/full/10.1080/02786826.2013.867297 KEYWORDS: RAMAN; Laser Beam Propagation; Marine Aerosol Environment; Marine turbulent boundary Layer; MABL; Thermal blooming; Laser Environmental Effects Definition and Reference; LEEDR

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Develop a software tool to transform and create synthetic sensor data from information received by a different sensor. DESCRIPTION: Modern platforms may contain a variety of sensors such as sonars of varying frequencies, cameras, and magnetic sensors. Often times, target information is collected by one or more sensors, but not by all of the sensors. This can lead to an increased number of test runs against targets to ensure each sensor, and associated algorithms, have an opportunity to collect target information in a variety of environmental conditions. The Navy seeks an innovative tool to transform sensor and metadata from a given system or frequency into realistic synthetic data from another sensor. For example, the transformation tool should be capable of transforming real data collected by a side scan sonar (SSS) into synthetic data representative of other sensor modalities, such as an SSS of a different frequency, a forward-looking sonar (FLS), or an electro-optical camera. In addition, this tool would be able to reconstruct a synthetic target in different orientations, with varied degrees of burial, and with adjacent imagery in varying bottom types (e.g., complex, noncomplex). The information created with this synthetic data generation tool will be used to develop and train automatic target recognition (ATR) algorithms. Sensor data to be generated should use complex physics-based models and represent objects in the subsea environments including mine-like objects. Providing realistic synthetic data will improve ATR, operator responses, reduce operator uncertainty, and improve decision-making. Machine Learning (ML) synthesis tools can enable development of realistic synthetic sonar for use with simulations. ML approaches are being leveraged for image and video processing applications, but a limiting factor is the availability of training data. High-quality synthesis approaches that utilize ML can also provide an alternate means to creating the large volumes of training data that are needed to ‘teach’ a deep learning algorithm. Sensors of interest include acoustic, optical, and magnetic sensors. Solutions must also be compatible with, and easily applied within Navy Expeditionary user displays and interfaces for conducting in-situ mission monitoring and post mission analysis. The proposer will analyze sensors and data formats, and develop data transformation solutions capable of incorporation onto Nvidia Graphic Processing Units (GPUs), ensuring compatibility with user interfaces employed in legacy Navy Expeditionary UUV systems. Synthetically generated images and data should be quantifiably similar to real data produced by the target sensor in terms of acoustic and optical reflectivity, and magnetic moment. That is, synthetic data scored as 'similar' should have ATR outcomes representative of real sensor data. ATR performance will be measured in Phase II. Methodologies and metrics for similarity scoring are encouraged as components of validity test proposals. PHASE I: Develop a concept for an innovative software solution capable of generating synthetic sensory data and metadata. During the Phase I base effort, the Government will provide a list of commercial sensor type, representative calibration targets and display/meta-data for sensors of interest to enable analysis of data structures and determination of data transformation feasibility and limits. Demonstrate the feasibility of the concept to successfully confirm that data from a real data set is transformed into synthetic data as if collected by other sensor modalities to include different sonar frequencies and types (e.g., FLS, Gap-filling sonar (GFS), Real Aperture Sonar (RAS), and Synthetic Aperture Sonar (SAS)), Magnetometer, and Optical Sensors. The Phase I Option, if exercised, will include initial design specifications and a capabilities description to build a prototype in Phase II. PHASE II: Develop, demonstrate, and deliver a software prototype system capable of creating synthetic sensor data and metadata from sensors identified in Phase I efforts for testing and evaluation; the prototype system will be compatible with and suited to future integration as a module of the Common Operator Interface, Navy (COIN)/NEXUS user interface. Develop the prototype sensor transformation tool. Synthetic data generated using this tool will be evaluated against baseline ATR algorithms it to determine if it meets Navy performance goals described in the Phase II SOW. Use operationally representative data for the demonstration. Identify performance and technical requirements to be met during evaluation. Prepare a Phase III development plan to transition the technology for Navy and other potential commercial use. In Phase II, develop and demonstrate performance of a prototype software module, incorporating their technical solution for synthetic data generation for sonar, optical and magnetic moment data. The transformed data set build time threshold is 3:1 with an objective of 24 hours or less, for distribution to fleet operators or other programs. PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the successfully matured technology as a software module of the Common Operator Interface, Navy (COIN)/NEXUS user interface as a component of Navy Expeditionary UUV systems. Technical support to further troubleshoot, further refine and better adapt the Phase II prototype deliverable will be provided by the contractor as the Navy conducts the full range of testing and evaluation of the module as a software upgrade to the UUV systems. Navy testing and evaluation will be included comparative analysis of real-world data sets collected by the Navy where actual representative targets have been added, with synthetically generated data sets which add the targets to the environment. ATR algorithms will be run on both data sets to verify effectiveness of the synthetic data generation tool. Refinements by the contractor during Phase III may include, but are not limited to, software certification for cyber security compliance, and an addition or improvement of features and attributes to enhance user interfaces. Application of the product may reasonably be expected to extend to commercial contexts such as automated object recognition for autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) engaged in maritime salvage and field inspection for the oil and gas industry. REFERENCES: 1. Brad Walls (Mar 23 2021). Using the Unreal Engine as a High Fidelity Simulation for Data Creation, The Fifth Annual Workshop on Naval Applications of Machine Learning, Underline Science Inc. https://underline.io/lecture/14817-using-the-unreal-engine-as-a-high-fidelity-simulation-for-data-creation 2. Ilisescu, Corneliu et al. “Responsive Action-based Video Synthesis.” Proceedings of the 2017 CHI Conference on Human Factors in Computing Systems, May 06-11, 2017, pp. 6569 6580. https://arxiv.org/pdf/1705.07273.pdf 3. Wang, Ting-Chun et al. “Video to Video Synthesis.” NIPS Proceedings, 2018. https://arxiv.org/abs/1808.06601 4. You, Xinge et al. “Kernel Learning for Dynamic Texture Synthesis.” IEEE Transactions on Image Processing, Vol.. 25, No. 10, OCTOBER 2016. Kernel-Learning-for-Dynamic-Texture-Synthesis.pdf 5. Dosovitskiy, Alexey and Brox, T. “Generating images with perceptual similarity metrics based on deep networks.” NIPS Proceedings, 2016. https://papers.nips.cc/paper/6158-generating-images-with-perceptual-similarity-metrics-based-on-deep-networks KEYWORDS: Mine Countermeasures; MCM; Synthetic Data; Software; Unmanned Undersea Vehicles; Mines; Navy Expeditionary; Collection of target information on UUVs

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Develop an automated capability to generate exams with answer keys using Artificial Intelligence or Machine Learning (AI/ML)-powered data mining for Undersea Warfare (USW). DESCRIPTION: When systems are updated, development of training materials for the updated system can be labor-intensive and can take significant time to prepare. Meanwhile, students are being taught using potentially deprecated information. This is particularly true when the system is complex. The problem is compounded when updates occur frequently. USW system operation is a skill that is highly perishable, increasing the importance of accurate, updated training products. The importance of USW to national security necessitates system updates on a frequent basis. This makes developing current, up-to-date training materials for the updated capabilities key to harnessing the power of these systems. Today, over 450 sailors graduate annually from Surface Combat Systems Training Command San Diego (SCSTC-SD). To stay current with the ongoing efforts to continually update USW related course materials, exams are currently still manually produced, administered, and graded by hand, which consumes numerous man-hours that could be better spent providing course instruction and running tactical scenarios in high fidelity virtual trainers. Creating a Surface Force USW Knowledge Bank to augment Instructional Design, with up-to-date USW References, would significantly decrease this workload. The Navy seeks a solution that can (1) mine documentation for existing capability associated with the SQQ-89 and UYQ-100, (2) autonomously develop a core USW training knowledge base with associated exam questions and answer keys, and (3) automatically identify deltas to the core knowledge base associated with approved capability improvements and appropriately adjust the core knowledge base to remove deprecated content. AI/ML techniques such as natural language processing (NLP) and data mining have improved markedly in recent years. The Navy seeks a technology that automatically generates tests and answer keys from functional description documents (FDDs), concepts of employment (CONEMPs), and concepts of operation (CONOPs), and other USW References created during capability developments and deployment. The AI/ML technology will demonstrate capability at a complexity level that is analogous to the target USW systems but need not be a military system. The Government will provide data and specifications as needed to demonstrate the capability. Utilizing various USW References including the FDD, CONEMPs, and CONOPs created during capability developments, this innovative tool would utilize AI/ML to search these references and generate an automated testing function. This tool would produce a test bank comprised of applicable and correct questions, generate an answer key, grade, and provide test score results as applicable. Automated exam generation capability, based on material(s) of interest, does not currently exist due to the complex and changing system requirements and reference updates. This tool will also appropriately adjust the core knowledge base to remove deprecated content. There is currently no technology available that smartly mines data from selected materials to document, categorize, and interpret information then generate up-to-date exams, and subsequent administration. Furthermore, current technologies do not allow for the interpretation and evaluation logic to verify that sailors are fully understanding and experiencing the intended system improvements. USW reference resources are drafted and finalized over time and not necessarily in a prescribed order as they are continuously updated. Vendors provide the FDD outlining the capability of the system, displays, unique features, operating instructions, etc. However, the FDD does not explain how the updated system will function on deployment or how the sailor would employ the system specifically for anti-submarine warfare (ASW). The schoolhouse instructors manually translate the FDD into training material by creating a Modernization Training Team PowerPoint deck for training. AI/ML could be utilized to glean appropriate training materials from the FDD more efficiently, and effectively, than an instructor can manually. The CONEMP provides a big picture look regarding how the sailor should use this updated system capability at a high level specifically, what is the employment and how this fits into the totality of tools at their disposal. The information in this document must also be included in the repertoire of training materials. As system engineers evaluate the system, they generate the CONOP which drills down into the details explicitly aimed at how to hunt for submarines. It describes exactly how the operator should use the system for this specific purpose. An AI/ML tool could be used to continuously mine for appropriate course material incorporating the operating requirements of the system related to the overall ASW process. While AI/ML can be utilized to mine course materials from the FDD, CONEMP, CONOPs, and existing training PowerPoint documents, a more tailored and unique AI/ML capability would be necessary to evaluate the more subjective issue of whether sailors are understanding how to use the new system attributes specifically for ASW. AI/ML would need to be utilized to generate training materials and questions designed to analyze sailor understanding of the system nuances and how it works within the larger platform for ASW. The School House gets the FDD with a copy of the code associated with the update/upgrade. They do not have CONEMP or CONOP immediately. As these documents and additional USW references, like Operator Employment Guides, become available over time, the instructors will need the flexibility to engage the AI/ML tool to include these materials in ongoing training course material updates. The new technology will be introduced in parallel with capability fielding and provide training personnel with the most current information to train students. This will increase the speed at which the Fleet can adopt transformational capabilities to maintain a warfighting edge. The threshold would be reducing the delay specific to developing training products by a factor of two. PHASE I: Develop a concept for an automated capability to generate exams with answer keys using AI/ML-powered data mining that meets the parameters in the Description. Demonstrate that the concept can feasibly meet the requirements through analysis and modeling. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II. PHASE II: Develop and deliver a prototype automated capability to generate exams with answer keys using AI/ML-powered data mining. Demonstrate functionality under the required service conditions. Demonstrate the prototype performance through the required range of parameters given in the Description. The prototype will be tested by Government subject matter experts (SMEs). PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to Navy use. The final product will consist of a capability to generate exam questions and answer keys from system documentation, generate delta questions and associated keys, and appropriately adjust the core knowledge base to remove deprecated content. The resultant technology will be used and tested by the training and Integrated Logistics Support (ILS) team supporting Undersea Warfare Systems such as AN/SQQ-89A(V)15 and AN/UYQ-100. The technology developed could also be used to develop training products for any complex skillset subject to rapid change due to policy or technology changes. Examples of such complex skillsets include law enforcement and air traffic control. REFERENCES: 1. Deshpande, Adit “Deep Learning Research Review Week 3: Natural Language Processing.” 10 Jan 2017. https://adeshpande3.github.io/Deep-Learning-Research-Review-Week-3-Natural-Language-Processing 2. Mooney, Raymond J. and Razvan Bunescu “Mining Knowledge from Text Using Information Extraction” SIGKDD Explorations June 2005: Vol. 7:1. https://www.cs.utexas.edu/~ml/papers/text-kddexplore-05.pdf 3. Navy Fact Files “AN/SQQ-89(V) Undersea Warfare / Anti-Submarine Warfare Combat System.” Updated 20 Sep 2021. https://www.navy.mil/Resources/Fact-Files/Display-FactFiles/Article/2166784/ansqq-89v-undersea-warfare-anti-submarine-warfare-combat-system/ 4. Navy Fact Files “AN/UYQ-100 Undersea Warfare Decision Support System (USW-DSS).” Updated 20 Sep 2021. https://www.navy.mil/Resources/Fact-Files/Display-FactFiles/Article/2166791/anuyq-100-undersea-warfare-decision-support-system-usw-dss/ 5. Piontek, Mary E. “Best Practices for Designing and Grading Exams.” Center for Research on Learning and Teaching (CRLT) Occasional Papers No. 24. 2008. http://www.crlt.umich.edu/sites/default/files/resource_files/CRLT_no24.pdf KEYWORDS: Automatically generate tests and answer keys; Artificial Intelligence and Machine Learning; AI/ML; natural language processing; NLP; functional description documents; FDDs; concepts of employment’ CONEMPs; concepts of operation; CONOPs

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Develop a scalable prototype system to produce JP-10 from non-fossil sustainable energy resources. DESCRIPTION: The objective is to develop a scalable synthetic approach to producing JP-10 that meets military specification, MIL-DTL-87107E from non-fossil sustainable energy resources such as carbon dioxide (CO2), biomass, and waste products. JP-10 is primarily composed of exo-tetrahydrodicyclopentadiene, C10H15, and synthesized by the hydrogenation, isomerization, and separation and purification of dicyclopentadiene, a petroleum-based resource. The proposed synthetic process may be chemical or bio-manufacturing in nature, and must be low in temperature (not to exceed 500 °C) with pressures not to exceed 600 psi. Initial prototype demonstrations of the technology will be up to 1 gal/day. For future design and scaling purposes the objective will be to synthesize 1,000 gal/day of finished JP-10 from a process that can be placed in a Conex shipping container. PHASE I: Define, develop, and perform initial laboratory assessment of the proposed synthetic process to validate the technical feasibility of the synthetic approach to producing JP-10 that meets MIL-DTL-87107E. Perform analysis of the fuel and determine initial process selectivity. Based on the laboratory approach, define and develop a concept for a modular, scalable JP-10 synthetic process, that can meet the performance and design specifications listed in the Description. Develop a Phase II plan. PHASE II: Develop a prototype process based on the work achieved in Phase I. The prototype will be designed to produce 1 gal/day of finished JP-10 that meets MIL-DTL-87107E. The prototype will establish performance parameters and proof of concept for development of full-scale process in Phase III. PHASE III DUAL USE APPLICATIONS: The integrated 1 gal/day prototype process will provide equipment, process, design criteria, energy and material balance, and establish operational performance parameters. This data will be used to provide the design criteria for transitioning the technology to larger capacities. A 100-1,000 gal/day process will be developed and tested in Phase III. The design criteria and performance parameters will enable the system to be designed into a Conex container for transport. REFERENCES: 1. 1. Department of Defense, MIL-DTL-87107E PROPELLANT, HIGH DENSITY SYNTHETIC HYDROCARBON TYPE, GRADE JP-10 12-January-2012. 2. 2. Department of the Navy Climate Action 2030, 24 May 2022. https://www.navy.mil/Portals/1/Documents/Department%20of%20the%20Navy%20Climate%20Action%202030.pdf KEYWORDS: JP-10; Fossil Fuel; Prototype; Sustainable; Energy; Synthesis

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy;Integrated Network Systems-of-Systems OBJECTIVE: Develop a lightweight (prioritizing weight above efficiency) integral turbogenerator in a compact package intended for embedded integration into a Vertical Take-off and Landing Unmanned Aerial System (VTOL UAS) for support of high-power conditions on takeoff and landing. DESCRIPTION: Current VTOL UASs in development, and concepts being pursued by both commercial and military operators, require high-power delivery on takeoff and landing segments that can be delivered by small turbogenerators also in development. At small scales, around 50 shaft horsepower (shp) output, turbines with centrifugal compressors can provide high specific power but are typically less efficient than equivalent power reciprocating engines. Fabrication of turbines without the need to couple to a low-spool shaft for thrust generation, and instead coupling to a high-speed generator, can provide a path toward delivering high power levels during VTOL mission segments. New hybrid power architectures and electrical components can then support a serial or parallel propulsion system that could leverage the very low Brake Specific Fuel Consumption (BSFC) of the primary reciprocating engine, and provide additional power via a small lightweight turbogenerator that could generate sufficient power for the short-segment VTOL maneuvers, with much lower requirements on specific fuel consumption due to the short (on the order of one minute) durations involved. Modifying the cycle of a turbogenerator to optimize the design for high power output without concern for SFC could simplify the design as well as reduce the cost of the unit by lowering aerodynamic design tolerance requirements, and reducing the thermal cycle requirements in terms of pressures and temperatures, as well as simplifying the mechanical design without the need to couple a low-speed turbine to generate thrust. KEY SMALL AUXILIARY LIGHTWEIGHT TURBOGENERATOR ENGINE (SALT-E) PARAMETERS • Multi fuel operation on F-24, JP-8, JP-5, Diesel • Specific fuel consumption not to exceed 3.0 lb / hp-hr while operating at maximum design power level at 15,000 ft MSL STD day • High specific power > 2.0 shp/lb turbine output (Threshold), 4.0 shp/lb (Objective) including the generator system (does not include power control unit or fuel system) • System must include integral generator operating at peak efficiency of > 90% • Cold, electric remote start capability (-20°C) without ground support • Capable of operating in marine environments for sea-based operations • System should include air bearings to allow for oil-free operation and that include material systems that are marinized and capable of operation in sea-based environments with a time between overhaul (TBO) target for the design of >1500 hrs • Recuperators should be included in the design to increase BSFC (lbm/hr/kW-electric output) at an appropriate effectiveness (target minimum of 70% effectiveness) and weight • Recuperator temperatures that can support turndown to power level angles (PLA’s) with an objective of 30% • Capability of high specific temperature materials for the turbine wheel should be included • Multi-orientation capability: 10 minutes continuous operation at maximum power with a change in orientation of 90 degrees from about a horizontal axis without degradations to operability, durability or shaft power output. • Demonstrate a minimum of 150 hr durability for initial test articles • Must be capable of continuous operation at peak load for 24 hours • Unit must be capable of a minimum of 14 shp output (at the turbine shaft) and not more than 60 shp at sea level standard day conditions PHASE I: Develop a test unit turbine section with a measured output of 14 - 60 shp continuous power output with a specific power of >2.0 shp/lb for the turbine system. System should include design and consideration of air bearing material systems and designs compatible with marinization requirements for operations in salt spray environments. PHASE II: Integrate the turbine with the generator and demonstrate a fully integrated electrical machine capable of operations with simulated load profiles with controlled power output for supporting a VTOL hybrid power system. The combined unit should demonstrate continuous performance for up to 12 hours with logistical fuels. PHASE III DUAL USE APPLICATIONS: Demonstrate the unit in a VTOL UAS flight test asset in a hybrid power system demonstration. Ground testing in an altitude cell will confirm altitude capability up to 15k ft MSL altitude. Flight testing will demonstrate the controllability of the unit and the viability of the hybrid power architecture. Multiple commercial entities are developing, and have interest in small VTOL UAS for delivery of medical and other supplies to remote areas. Several capabilities exist that are less robust, and less capable than what a power turbine could enable in terms of payload and range capabilities, and in inclement weather. Likely there would be significant commercial interest in the technologies and capabilities developed in this type of power unit for both UAS and portable ground power applications. REFERENCES: 1. Cinar, G.,Markov, A., Gladin, J., Garcia, E., Marvis, D., Patnaik, S. (2020). Feasibility assessments of a hybrid turboelectric medium altitude long endurance unmanned aerial vehicle. AIAA Propulsion and Energy 2020 Forum. https://doi.org/10.2514/6.2020-3577. 2. Pamireddy, S. R. (2020). Comparison of power sources with scalability effects for rotorcrafts (Order No. 28149981). Available from ProQuest Dissertations & Theses Global. (2503638599). Retrieved from https://niu.idm.oclc.org/dissertations-theses/comparison-power-sources-with-scalability-effects/docview/2503638599/se-2. https://www.proquest.com/docview/2503638599?pq-origsite=gscholar&fromopenview=true 3. Avera, M., & Singh, R. (2019, October). Scalability of Hybrid-Electric Propulsion for VTOL UAS. In Proceedings of the NATO Research Symposium on Hybrid/Electric Aero-Propulsion Systems for Military Applications, Trondheim, Norway (pp. 7-9). https://www.sto.nato.int/publications/STO%20Meeting%20Proceedings/STO-MP-AVT-323/MP-AVT-323-10.pdf KEYWORDS: Turbogenerator; turbine; generator; recuperator; vertical take-off and landing; VTOL; hybrid; propulsion; hybrid-electric; hybrid propulsion; unmanned aerial system; UAS

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): FutureG; Trusted AI and Autonomy OBJECTIVE: Design a distributed, coherent sensing solution to generate a spectrum map of available channels in sparse or dense spectral environments for channel allocation in a decentralized multi-hop network. Develop a scheme for sharing spectrum sensing results across the network for all channels to reach distributed consensus on the spectrum map between multiple geographically-dispersed nodes. DESCRIPTION: Wireless multi-hop networks, and the understanding thereof, are key components to military and commercial communications. These networks are non-centralized, highly dynamic, and often either sparse or dense. With wireless communications and networking now necessitating dynamic spectrum allocation, such as with fifth generation (5G) and sixth generation (6G) cellular technology, military and commercial users must develop a more coherent approach to understanding spectral environments for maintaining reliable connectivity. There are many signal processing solutions for detection and classification of spectral energy, such as those based on machine learning (ML). Standard ML metrics are often used to evaluate the accuracy of these techniques, such as number of false positives/negatives. System performance may also be quantified with temporal metrics such as latency and speed. While being agnostic to any particular sensing approach is the objective, it may be through the course of this STTR topic that a greater understanding of ML characteristics specific to the radio frequency (RF) modality is a key component to coherently linking multiple, geographically-dispersed sensing systems for the complete spectral mapping that fully supports dynamic allocation in sparse and/or dense environments. Indeed, sharing ML data model updates instead of in-phase and quadrature (I/Q) data is much more efficient. An adequate understanding to baseline spectral activity can be achieved through sensing at a single node, but distributed spectrum sensing would provide much greater fidelity on activity for dynamic spectrum allocation. Metrics similar to those used for quantifying accuracy and performance of a single node may also be used for evaluating these distributed sensing systems with multiple nodes. Overcoming the coherence challenges behind a distributed spectrum sensing approach would enable a network-wide mapping of available channels. This awareness of the spectral environment would then inform proper channel allocation for resilient communications that support both military and commercial users. It would also enable adaptation within the spectrum, as well as identification of primary and secondary users. The solution to these problems must be computationally efficient and require little overhead to share sensing results/updates to nodes across the network. The goal is for coherency to be as agnostic to the sensing technique as possible. This STTR topic will develop the foundational mathematical analysis to address coherence for distributed sensing in dynamic spectral environments. This topic also seeks an initial design of a methodology for disseminating results and awareness across the network to achieve distributed consensus among the sensing nodes for applications such as adapting communications within the spectrum and identifying primary and secondary users. The innovation and focus is on solving coherency issues in order to map out spectral environments for dynamic spectrum allocation, and on a means for efficiently sharing results to multiple nodes across the network to reach a desired end state of distributed consensus on spectral activity for dynamic allocation. PHASE I: Conduct analysis to design an approach for coherent distributed sensing. Use this analysis to inform and demonstrate a proof of concept that provides a network-wide mapping of available channels. Perform a trade study and literature survey on sharing results for distributed consensus of spectral activity. PHASE II: Refine, test, and prototype a scalable, mathematically-founded approach to coherent distributed sensing for network-wide mapping of available channels with means for sharing results/updates across the network to reach consensus amongst the nodes. PHASE III DUAL USE APPLICATIONS: Support knowledge transfer and demonstrations/testing of the capability developed as a result of Phase II. The transition of a spectral mapping capability will help both military and commercial users with spectrum sharing and dynamic spectrum allocation amid the current proliferation of 5G, and future proliferation of 6G, communications and networking technologies. The envisioned coherency techniques for distributed sensing and means for disseminating consensus to enable dynamic spectrum allocation can provide many opportunities with military and commercial transition. REFERENCES: 1. Olivieri, M.P., Barnett, G., Lackpour, A., Davis, A., and Ngo, P. “A Scalable Dynamic Spectrum Allocation System with Interference Mitigation for Teams of Spectrally Agile Software Defined Radios,” First IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks, 2005. DySPAN 2005., 2005, pp. 170-179, doi: 10.1109/DYSPAN.2005.1542632. 2. Rajesh Babu, C., Ramana, K., Jeya, R., and Srinivasulu, A. “COCO: Coherent Consensus Scheme for Dynamic Spectrum Allocation for 5G.” Complexity and Robustness Trade-Off for Traditional and Deep Models 2022 (Special Issue). 6 Jul 2022. 3. Tran, C. et al., “Dynamic Spectrum Access: Architectures and Implications,” MILCOM 2008-2008 IEEE Military Communications Conference, 2008, pp. 1-7, doi:10.1109/MILCOM.2008.4753454. 4. Zhao, Q. and Sadler, B.M. “A Survey of Dynamic Spectrum Access,” in IEEE Signal Processing Magazine, vol. 24, no. 3, pp. 79-89, May 2007, doi:10.1109/MSP.2007.361604. KEYWORDS: Distributed Sensing; Network Mapping; Dynamic Spectrum Allocation; Spectrum Sharing; 5G; 6G; Wireless Communications; Distributed Consensus; Wireless Multi-hop Networks

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Hypersonics OBJECTIVE: Establish combined modern analytical methods and a resultant predictive model for characterizing Hydroxyl Terminated PolyButadiene (HTPB) polymer binder resin in parallel with chemical cure, mechanical properties, and aging assessments, to support the successful development and use of military grade HTPB in existing and emerging solid rocket motors. The combined analytics and predictive model will reliably correlate binder resin chemical and physical properties with gum stock and formulation quality, provide key characterization parameters leading to updated military specification(s), and improved sourcing of HTPB for successful manufacture of rocket motor, ejection seat, and related propellants. DESCRIPTION: The DoD has a need for proper analytics coupled with predictive material models for Hydroxyl Terminated PolyButadiene (HTPB) as used in rocket motors and other energetic formulations. Even when meeting military specifications, the binder resin, often and unpredictably, suffers from a too short and variable pot-life, slow and incomplete curing, poor gum stock mechanical properties, and poor aging behavior. As a result, DoD propellant production is often greatly hindered. As the need for more of this DoD-specific HTPB binder resin continues to grow, the fundamental chemical and physical properties of this polymer that lead to desirable rocket motor formulation characteristics remain poorly understood. One major challenge for HTBP variants used in energetic formulations is that there are several ways to meet outdated military specifications (WS 20700, dated June 1981) that do not define necessary formulation-enabling chemical properties. An HTPB lot can meet specifications as a monodisperse straight-chain, telechelic polymer, or as a complex mixture of variable length, distribution of branches, and reactive sites. Ultimately, this variability leads to inconsistent and unwanted end use behavior. For instance, the variability in branching and the locations of the hydroxyl groups greatly affects how the polymer cross-links, which is magnified by other ingredients when formulating a rocket motor grain. Another example of the problems facing end users of HTPB binder is that processing techniques and the variability in the distribution of reactive sites greatly change the effectiveness of antioxidant protocols when formulating. These are only two examples of the problems associated with the currently available supply of HTPB. OSD and the DPA Title III office recognized the inadequacy of the weapon specification test requirements in determining whether any given lot of HTPB will work sufficiently in a propellant formulation and as such recommended additional tests be performed [Ref 1]. Further, the hydroxyl value of the product obtained from the current, domestic supplier appears to have decreased from historical levels upon attempting to target a lower hydroxyl functionality initially sought for prior program requirements. Concurrent with this change, formulators are finding it even more difficult to consistently produce a propellant that meets their requirements due to the polymer not having sufficient molecular weight or functionality fraction to permit the manufacture of a robust propellant, especially for air-launched applications. To date, private industry has been unable to solve the technical challenges associated with analytical methods development, detailed understanding of the chemistry, reaction kinetics, safety, reproducibility, and scalability in order to produce a reliable HTPB variant and associated specifications. While there have been prior efforts to develop a greater understanding of the HTPB polymer characteristics [Refs 2-5], to date there has been no definitive model developed using appropriate, modern analytics to correlate polymer structure to performance. Future sources and suppliers of HTPB for energetic formulation use will require this type of analytically driven HTPB predictive model to inform updated military specifications and production practices. PHASE I: Identify and/or develop combinations of key analytical methods for correlating HTPB polymer system chemical and physical characteristics with gum-stock and formulation end use properties leading toward development of a strong predictive tool. HTPB samples of varying quality should be obtained from the Government and other contractor rocket motor manufactures to assist in Phase I material analytical method development efforts. The quality of the HTPB should not be defined as simply “good” or “bad” but will be assessed by quantifiable data pertaining to pot-life, degree of chemical cure, oxidative susceptibility, mechanical properties, specification, and any other relevant test results that relate binder ingredient characteristics to formulated rocket motor characteristic requirements. Generate needed characterization data otherwise unavailable from Government and other sources. Phase I should culminate in a planned framework approach to building a predictive model that correlates HTPB chemical, physical, and any other relevant properties to resulting gum-stock and formulation characteristics, describing the analytical methods and characteristics to be used and validated in Phase II. PHASE II: Refine HTPB polymer analytical methods and perform cure studies and aging assessments as needed to fully develop and validate the predictive model. The model should incorporate the capability to predict cured polymer gum stock mechanical properties, cure characteristics including pot-life, and aging characteristics based on a suggested set of analytically generated chemical and physical properties data. Make final model modifications based on validation studies and complete model development. The model will serve to ensure that a fully tested lot of HTPB, using the newly developed and defined set of analytical characterization tests, will meet required gum-stock pot life, cure profile, and aging characteristics. PHASE III DUAL USE APPLICATIONS: Using the developed HTPB model, work with Government and other contractor entities, as applicable, to develop robust processing and controls to produce HTPB at pilot scale meeting desired material chemical and physical characteristics as previously identified that lead to successful gum stock formulations (i.e., meeting various exemplar rocket motor formulation specification requirements). Additionally, the predictive model and associated data will be used to assist in development a modern DoD specification for HTPB. Outcomes from work under this STTR topic would likely benefit other industrial/commercial uses for HTPB type polymer resins where similar chemical/physical property characteristics are critical to material performance (i.e., rubbers). REFERENCES: 1. Funding Opportunity Announcement (FOA) #FA8650-19-S-5010 Call 009 “Hydroxyl Terminated Polybutadiene (HTPB) Production Capability for DOD Munitions Project”, 2021. 2. Vilar, W. D., Menezes, S. M. C., & Akcelrud, L. (1994). Characterization of hydroxyl-terminated polybutadiene. Polymer Bulletin, 33(5), 557–561. doi:10.1007/bf00296164 3. Vilar, W. D., Menezes, S. M. C., & Akcelrud, L. (1994). Characterization of hydroxyl-terminated polybutadiene. Polymer Bulletin, 33(5), 563–570. doi:10.1007/bf00296165 4. Regan, P. R., Teo, H. H., Booth, C., Cunliffe, A. V., & Hudd, A. L. (1985). The molecular characteristics of hydroxyl-terminated polybutadiene. British Polymer Journal, 17(1), 22–26. doi:10.1002/pi.4980170106 5. Prine, N. 2018 ‘Characterization and Selection of Hydroxyl-Terminated Polybutadiene Polymers for High-Strain Applications’, Honors Thesis, University of Southern Mississippi, Hattiesburg, MS. KEYWORDS: Hydroxyl-Terminated Poly Butadiene; HTPB; predictive model; polymer analytics; material specification; Solid Rocket Motor; SRM; propellants; explosives; energetic materials

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials OBJECTIVE: Develop an electrochemical machining process which has lower up-front non-recurring engineering expenses while still enabling fast material removal for a reduction in machining times of turbine engine components and enabling more fuel efficient gas turbine engines. DESCRIPTION: Electrochemical machining (ECM) processes have been utilized for subtractive machining of aerospace materials such as nickel and titanium alloys. The process is particularly attractive due to its high metal removal rate in tough or heat-resistant materials common to the requirements of propulsion and power generation engines. The surface quality provided by ECM is also advantageous due to the low roughness and no heat affected zones or recast layer. In addition, the lack of electrode wear can lead to high process repeatability and lower production costs. ECM is relevant for a number of Navy propulsion needs, including compressor and turbine airfoils, integrally bladed rotors (IBRs) or bladed disks (blisks), cases, disks, and combustor components. IBRs and blisks, for example, are particularly expensive for 5-axis Computer Numerical Control (CNC) machining due to challenging materials (e.g., Ti6242, Inconel 718), tight geometric tolerances on 3D surfaces (e.g., +/- .001-.003”), and smooth surface finish requirements (e.g., =10 µin Ra). In addition, new IBR and blisk designs feature tighter blade-to-blade spacing, intentional mistuning, and thinner walls, which further increase costs for both new engine designs and Navy sustainment needs. These requirements increase the potential need for an ECM manufacturing solution. In addition, advanced designs are challenging the limits of current manufacturing techniques. Sharper leading edges, thinner walls, exotic tip geometries, and more complex curvatures can improve the overall engine efficiency or stall margins, but are more expensive, time consuming, or impossible to manufacture with conventional techniques. New material systems are being developed, such as titanium aluminides, high entropy alloys, and refractory alloys, which often have improved mechanical properties or heat resistance, increasing the challenge for contact-based machining processes and furthering the need for non-contact electrochemical methods. Finally, there is growing interest in near-net-shape processes, such as low-cost casting or metal additive manufacturing. In these cases, a secondary subtractive machining process is often necessary to improve final part tolerance and reduce surface roughness. To take advantage of the single-part nature of near net components, the subtractive manufacturing process needs the ability to access hard-to-reach areas, an area where ECM can excel. The low forces and insensitivity to material mechanical properties makes ECM a promising manufacturing technique to address all of these concerns, but its adoption has been largely limited to high volume commercial applications. The primary barrier facing greater adoption of ECM is the up-front non-recurring engineering expense (NRE) and process development costs. ECM is inherently inaccurate but repeatable, requiring iterations of the tooling to achieve the necessary accuracy. This iterative process of electrode design and process parameter selection is largely based on intuition and has limited its use to a few specialized firms, which rely on the knowhow and experience of its personnel. In addition, the tooling can be damaged by short circuit conditions during the testing phase, which damage the electrode and workpiece, leading to a time-consuming re-manufacturing process. Given these challenges, the United States Navy is seeking improvements to the electrochemical machining process which can: • Reduce the upfront tooling and NRE expense associated with current ECM processes • Yield cost and lead time reductions of > 25% for turbine engine components including fan, compressor and turbine blades, advanced casing treatments and combustor liners, when compared to current best practices • Be used for next generation metal material systems and geometries, including nickel superalloys and high entropy alloys • Promote the standardization of ECM procedures, accessibility to the machining method for lower production rates, and ECM workforce development PHASE I: Demonstrate proof-of-concept manufacturing of the improved ECM process on a relevant material system (e.g., Ti64 or IN718). Identify major risks to the proposed solution through analysis and/or experimentation. Identify solutions to the major risks. Test the proposed solutions on a representative geometry. PHASE II: Address the risks and challenges by modifying or improving the baseline manufacturing technique demonstrated in Phase I. Additional manufacturing demonstrations will be performed on representative propulsion engine components and materials. Demonstration components will be inspected to identify quality issues (e.g., metallurgy impacts, surface defects), geometric tolerances, and material removal rates. A cost model will be developed demonstrating a pathway towards 25+% cost reduction and identifying the total manufacturing process chain (i.e., proposed technique + pre- or post-processing steps), the capital equipment and NRE costs associated with the proposed technique, and the operating expenses of the proposed technique. PHASE III DUAL USE APPLICATIONS: Create a full-scale component using the developed manufacturing technique which could be used for further performance evaluation including rig testing, spin pit testing, or flow testing. If successful, this technology would have wide application in commercial advanced manufacturing for a variety of products. REFERENCES: 1. Xu, Z., Wang, Y.(2021). Electrochemical machining of complex components of aero-engines: Developments, trends, and technological advances. Chinese Journal of Aeronautics, Volume 34, Issue 2, 28-53. https://www.sciencedirect.com/science/article/pii/S1000936119303462 2. Klocke, F., Zeis, M., Klink, A., Veselovac, D. (2013). Experimental research on the electrochemical machining of modern titanium- and nickel-based alloys for aero engine components. Procedia CIRP, 6, 368–372. .; https://www.sciencedirect.com/science/article/pii/S2212827113001145 KEYWORDS: Advanced manufacturing; electrochemical machining; compressor; turbine; jet engine; blisk; IBR; machining; surface finish

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Develop a low-cost, energy efficient synthetic approach to producing carbon-based composites from environmental carbon resources. DESCRIPTION: The objective of this STTR topic is to develop a low-cost, low-energy synthetic approach to producing carbonaceous materials to be used in carbon-based composites to advance defense materials for the warfighter. These materials include carbon fibers, carbon nanotubes, carbon nanofibers, graphene, and graphite. Carbonaceous materials are typically used as fillers in polymer-matrix composites and ceramic-matrix composites. There is growing interest in utilization in Li-ion batteries, capacitors, and high strength building materials. The proposed synthetic process will reduce the complexity and cost associated with utilizing environmental carbon resources to synthesis the carbonaceous material while maximizing yield and purity. PHASE I: Define the specific carbonaceous material to be synthesized, utilizing environmental CO2. Define, develop, and perform initial laboratory assessment of the proposed synthetic process to validate the technical feasibility of the approach to producing the carbonaceous material. Perform analysis of the material and determine initial yield and purity. PHASE II: Based on findings in Phase I, define and develop a concept to produce kilogram-scale quantities of carbonaceous material. Produce selected materials and determine the physical characteristics (size and shape) along with strength, thermal and electrical conductivities, impurities, and yield as a function of changes in synthetic conditions. From the analysis and characterization, determine the appropriate steps to maximize CO2 usage, minimize energy, and costs associated with the approach. Identify Navy operational platform applications that are likely to benefit the most from this technology. Conduct a demonstration of the process and technology. PHASE III DUAL USE APPLICATIONS: Identify opportunities where carbonaceous materials can be utilized from an installations / building materials perspective that could benefit Naval and commercial facilities. Provide a cost-benefit analysis to show effects of utilizing CO2 on cost and production of material. REFERENCES: 1. Recent applications of carbon-based composites in defence industry:A review, Defence Technology, https://doi.org/10.1016/j.dt.2022.03.006 2. Department of the Navy Climate Action 2030, 24 May 2022, https://www.navy.mil/Portals/1/Documents/Department%20of%20the%20Navy%20Climate%20Action%202030.pdf KEYWORDS: carbon-based composites; carbon fibers; carbon nanotubes; carbon nanofibers; graphene; graphite; synthesis

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Develop an autonomous, long-duration, directional ambient sound sensing system capable of being integrated into a variety of platforms including floats, gliders, and ocean observation buoys. The system should output soundscape-related information in a manner that is scaled to match platform communications bandwidth. DESCRIPTION: Sound waves generated by natural (both abiotic and biotic) and anthropogenic sources convey information about both the source and the environment in which they travel. Underwater recordings of ambient sound have been previously used to estimate local weather (wind, rain), to identify the presence/absence of marine organisms, and, particularly when directional information is included, to characterize the undersea environment. These systems, however, have not found widespread usage in the near-real-time reporting systems that currently exist in ocean observing networks (e.g., systems of floats and gliders, observational buoy networks). This STTR topic seeks to develop a low power (~1 W), long duration (months to years) system that can be widely integrated into ocean observing networks. Successful solutions will include onboard processing to provide generalized soundscape information, including sound intensity levels as a function of frequency and direction (both horizontal and vertical), event detection, and scalable reporting options that can be matched to host platforms (e.g., low data rate satellite communications, moderate data rate cellular communications). The system should output soundscape-related information in a manner that is scaled to match platform communications bandwidth. Innovations are anticipated at both the sensing level, particularly for the directionality of ocean sound and its use in characterizing the ocean environment, and at the onboard processing level where the information content of ambient sound is efficiently and autonomously extracted from the raw data. The successful solution will be scalable to wide-region distributed sensing (e.g., 10’s to 100’s of sensors throughout a sea, or 1000’s of sensors distributed throughout the world’s oceans). PHASE I: Develop an initial concept design that can accommodate various host platforms including floats, gliders, and observation buoys. The concept design should include sensing concept and configuration, mechanical packing, power consumption, communication interfaces, sensor (re)calibration methodology, algorithms to extract the information content of the ocean sound, and estimated data rate(s). Algorithms are expected to be tested on previously collected or simulated data (e.g., passive acoustic data held by the NOAA National Centers for Environmental Information). PHASE II: Develop a prototype autonomous, long-duration, directional ambient sound sensor, integrate it into a host platform, and use real-world data to analyze its performance including sensitivity, self-noise, dynamic range, direction-resolving capability, power consumption, longevity, and sensitivity stability. PHASE III DUAL USE APPLICATIONS: Demonstrate the use of a regional network of sensors (e.g., 10’s of systems) including deployment, data collection/communication, and data analysis (e.g., generalized soundscape information and event detection). Naval applications of this system include the capability to validate and fine-tune ambient sound models and databases in operational environments, including real-time updates in the temporally and spatially varying ocean. Although the direct sensor output data will be unclassified, its use in direct coordination with Navy ambient sound models and databases may be CUI or classified. Commercial application of this technology is anticipated to be tied to the blue economy, including the detection of protected species in areas of interest to commercial fishing and offshore wind technologies. REFERENCES: 1. Vagle, S., Large, W. G., & Farmer, D. M. (1990). An evaluation of the WOTAN technique of inferring oceanic winds from underwater ambient sound. Journal of atmospheric and oceanic technology, 7(4), 576-595. https://doi.org/10.1175/1520-0426(1990)0072.0.CO;2 2. Van Uffelen, L. J., Roth, E. H., Howe, B. M., Oleson, E. M., & Barkley, Y. (2017). A Seaglider-integrated digital monitor for bioacoustic sensing. IEEE Journal of Oceanic Engineering, 42(4), 800-807. https://doi.org/10.1109/JOE.2016.2637199 3. Siderius, M., & Gebbie, J. (2019). Environmental information content of ocean ambient noise. The Journal of the Acoustical Society of America, 146(3), 1824-1833. https://doi.org/10.1121/1.5126520 KEYWORDS: Ambient Noise; Soundscape; Sonar; Autonomous; Ocean Observing; Environmental Sensing

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Space Technology

OBJECTIVE: Develop innovative manufacturing methods to produce high-quality lightweight optical mirrors for use in space on microsatellites (microsats) and small satellites (smallsats), particularly at ultraviolet (UV) and extreme ultraviolet (EUV) wavelengths.

DESCRIPTION: The Navy seeks improvements in the manufacturing of lightweight optical mirrors to meet size and weight demands of compact optical systems designed for operation in space on the next generation of microsats being designed to study the ionosphere [Refs 1, 2] and other Navy applications. Availability of high-quality lightweight optics will allow for future mission growth. The Navy seeks to foster the development of affordable optical components and systems that could have broad application to space systems. Current mirror technology involves either fragile glass optics or metal or composite mirrors that have lower optical quality. Innovative substrate materials are sought with the ruggedness, mass, and material properties necessary to produce light weight high-quality optical elements. Innovative techniques are sought to polish and figure these substrates to yield the high optical quality reflective surfaces needed for the new class of remote sensing instruments.

Typical cube satellite (CubeSat) mirrors used in smallsats have been fabricated from special aluminum alloys that are hard enough to be polished with moderate difficulty. Their density is 2.7 g/cm3, leading to significant mass penalties. The example sizes range from a fixed flat mirror (3” x 3.5” by 0.080” thick) to a scanning mirror (2” X 3.5” by 0.375” thick). Improvements are sought in the density, stiffness, polishability, roughness, figure accuracy, and moment of inertia in the scanning case. Goals are figure accuracies of λ/4 at the working wavelength, scratch/dig of 60-40, rms roughness of < 1nm, Coefficient of Thermal Expansion (CTE) compatible with typical spacecraft materials (< 4ppm/K), low outgassing (CVC < 0.1% and TML < 1%), survival at temperatures of -50 – +60°C, and the ability to survive a NASA GEVS3 vibration specification and thermal test environment, all typical of the requirements imposed for flight on small spacecraft.

Technologies proposed should not contain hazardous or high outgassing materials and should be capable of being integrated into typical optical systems. It is desired that they be moderately (> 10-5 O-1/m) electrically and thermally conductive (> 10W/mK) to avoid developing static charge and thermal gradients in space. They should be durable and able to withstand normal optical component handling procedures. They should be delivered in an optically clean state and be robust enough to withstand precision cleaning and vacuum baking as part of normal spacecraft processing.

PHASE I: Demonstrate the feasibility of a concept for an innovative lightweight mirror technology meeting Navy needs for microsat optical systems in the ultraviolet/vacuum ultraviolet (UV/VUV). Demonstrate performance advantages over current technology by producing small (25mm or larger) flat sample mirrors that can be tested to Navy requirements. While exact mirror dimensions are not specified for Phase I, the awardee will establish that the concept can be scaled to sizes of 100 mm diameter or larger. Phase I technology is expected to focus on the small flat mirrors that are needed to fold optical systems into compact smallsat envelopes. The path to using this technology to produce curved mirrors should be defined.

Proposed mirror concepts should meet the following thresholds:

PHASE II: Develop a Phase II prototype mirror of the 100 mm size class for evaluation. The prototype will be evaluated to determine its capability in meeting the performance goals defined in Phase II Statement of Work (SoW) and the Navy’s need for lightweight flight mirrors. The prototype design should provide reflective areas no less than 90mm by 40mm (objective), and should show applicability to be utilized with various mirror geometries and spacecraft architectures. Deliver a minimum of five of these prototypes to the Navy for evaluation. Perform detailed analysis to ensure materials are rugged and appropriate for Navy application. Environmental, shock, and vibration analysis will be performed. Optical checks will include flatness, roughness, and reflectivity. Prototype concave mirrors of 25mm diameter and ~100mm Radius of Curvature (ROC) will be produced and evaluated.

PHASE III DUAL USE APPLICATIONS: Apply the knowledge gained in Phase II to build an advanced mirror, suitably configured for a smallsat application, including flight spares, and characterize its performance in the UV/VUV as defined by Navy requirements. Working with the Navy and applicable Industry partners, demonstrate application to a NAVY Space Test program (STP) flight test. Support the Navy for test and validation to certify and qualify the system for Navy use. Explore the potential to transfer the light weight mirror system to other military and commercial systems (NASA, University, Optics Industry).

Market research and analysis shall identify the most promising technology areas. Develop manufacturing plans to facilitate a smooth transition to the Navy.

REFERENCES:

1. Budzien, Scott; Fritz, Bruce; Stephan, Andrew; Marquis, Peter; Powell, Steven; O'Hanlon, Brady; Nicholas, Andrew; Dymond, Kenneth and Brown, Charles. “Comparison of second and third generation 135.6 nm ionospheric photometers using on-orbit and laboratory results.”, SPIE Proceedings, Volume 11131, CubeSats and SmallSats for Remote Sensing III; 1113102 (2019). https://doi.org/10.1117/12.2528791
2. Attrill, G.D.R.et al. “Coordinated Ionospheric Reconstruction CubeSat Experiment (CIRCE), In situ and Remote Ionospheric Sensing (IRIS) suite.” Journal of Space Weather and Space Climate, (2020) . J. Space Weather Clim. 11, 16, (2021). doi.org/10.1051/swsc/2020066.
3. “NASA General Environmental Verification Standards (GEVS), Rev. A, GSFC-STD-7000 (2013).” https://standards.nasa.gov/standard/gsfc-std-7000

KEYWORDS: Lightweight space qualified mirrors, mirror technology, optical fabrication, spaceflight optics, spaceflight structures; microsatellites; small satellites; cube satellites

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Advance integration of camera imagery collection and onboard processing for environmental sensing on low-power, long-duration oceanic gliders and/or profiling floats. The system should allow for two-way communication between the sensor and platform microcontrollers; and software architecture should be tunable to specific parameters, e.g., adaptive capability to turn on imagery collection at target locations or times (e.g., within a set distance from the surface or bottom). Onboard processing and file reduction should allow for near-realtime data delivery of select low-resolution imagery and/or analysis products from imagery via satellite comms (iridium, Starlink, etc.). DESCRIPTION: Long-endurance profiling floats and gliders are critical components of today’s ocean environmental monitoring systems with standard sensor payloads sampling scalar fields (e.g., temperature, salinity, fluorescence). These platforms, which are available as off-the-shelf units or manufactured in house at academic institutions, can be modified to carry additional specialized sensors. Such efforts are often targeted to a specific science need, but are rarely fully integrated with the platform, and exist primarily as one-off prototypes. The field of underwater optical imaging has a long history with significant recent advances afforded by continued development of low-cost, high-performance sensors and computational capabilities for onboard processing [Ref 1]. Recent developments have included optical sensing packages with low-power and small space requirements making them suitable for integration on long-endurance platforms [Ref 2]. The Navy seeks a fully integrated, low-power optical imaging system on long-endurance (~6 month mission capability) profiling platforms. While all components—the platform, optical sensing packages, and compression/analysis software—are available in some form as commercial off-the-shelf systems; integrated systems that allow for real-time delivery of compressed information are in their infancy. Additionally, most optical imaging systems appropriate for use on small displacement vehicles target imaging of plankton [Ref 3]. This STTR topic seeks a design capable of imaging both the near-field (order 1 cm) and mid-field (order 1 m) of view, with camera sensors capable of resolving both millimeter- and meter-scale objects. The system can consider either passive or active imaging techniques optimized for the euphotic zone. Imaging should extend both below and above the surface with potential sensing targets: relative motion of marine snow and particulates, near-surface bubble concentration, above-surface environmental conditions (e.g., films, white-capping). Critically, the design must be integrated allowing for adaptive sampling with the sensor package and include onboard processing capable of providing near-realtime data delivery of select low-resolution imagery and/or analysis products from imagery via satellite comms (iridium, Starlink, etc.). PHASE I: Identify hardware components that can meet the stated requirements. Develop a concept for onboard software, including analysis of bandwidth and data transfer constraints. Develop a design concept for the integrated optical imaging system. Analyze for strengths and weaknesses of the proposed design. Develop a design review to be conducted in Phase II. PHASE II: Develop and test a prototype system. Complete an analysis of the performance of the system and report on the results. Conduct multi-stage testing allowing for redesign between tests with initial tests in a surrogate ocean environment (e.g., lake or tank), interim test in the ocean under controlled conditions (e.g., coastal bay), and final test in the field under a range of environmental conditions. Develop and test both hardware and software systems. The final prototype should include a fully integrated sensing package capable of adaptive sampling and delivery of data via satellite. Analyze and report on the strengths and weaknesses of the final design based on results of the field tests. PHASE III DUAL USE APPLICATIONS: The developed technology has potential use in any DoD, civil, or commercial application that requires detailed information on the ocean environment as certain elements, like the presence of marine vegetation or surface slicks/films, are not easily sensed through other means. Field testing in Phase II will constrain the parameter space under which the system is operationally capable for the Navy. Other potential use sectors include the oil and gas industry (e.g., tracking of spills under ice), and state/federal marine life monitoring agencies (e.g., NOAA Fisheries Monitoring and Analysis Division). REFERENCES: 1. J. S. Jaffe, "Underwater Optical Imaging: The Past, the Present, and the Prospects," in IEEE Journal of Oceanic Engineering, vol. 40, no. 3, pp. 683-700, July 2015, doi: 10.1109/JOE.2014.2350751. 2. Picheral, M., Catalano, C., Brousseau, D., Claustre, H., Coppola, L., Leymarie, E., Coindat, J., Dias, F., Fevre, S., Guidi, L., Irisson, J.O., Legendre, L., Lombard, F., Mortier, L., Penkerch, C., Rogge, A., Schmechtig, C., Thibault, S., Tixier, T., Waite, A. and Stemmann, L. (2022), The Underwater Vision Profiler 6: an imaging sensor of particle size spectra and plankton, for autonomous and cabled platforms. Limnol Oceanogr Methods, 20: 115-129. https://doi.org/10.1002/lom3.10475 3. Ohman, Mark D., et al. "Zooglider: an autonomous vehicle for optical and acoustic sensing of zooplankton." Limnology and Oceanography: Methods 17.1 (2019): 69-86. KEYWORDS: optical imaging, underwater autonomous vehicles, ocean gliders

DESCRIPTION: Cooling of high power electronics via refrigerant evaporation presents a significant opportunity to reduce the size, weight, and power (SWaP) consumed by thermal management systems. Recent advances have led to demonstration of compact microchannel evaporators with heat transfer coefficients in excess of 100 kW/m2^K and low pumping powers. Condensers are often the largest component in a two-phase cooling system. Commercial condensers are typically shell and tube designs with heat transfer coefficients less than 5000 W/m^2K. Military systems often use a secondary coolant loop to transport heat from condensers. For example, naval platforms use a freshwater cooling system, while air platforms have a polyalphaolefin (PAO) coolant loop. Recent progress in metal additive manufacturing has enabled the fabrication of air heat sinks and cold plates with complex flow geometries. Additive manufacturing also allows for thinner walls, reducing weight and thermal resistance. Most metal additive manufacturing technologies are based on powder processing, with a limited number of alloys commercially available. Process parameters can greatly affect the microstructure and mechanical properties of the resulting metallic heat exchanger, leading to concerns about long term durability. Heat transfer enhancement using internal structures embedded inside flow passages is commonly used to increase local convection heat transfer, but has been limited to simple structures by conventional manufacturing techniques. Additive manufacturing can enable more complex structures, but demonstrations to date have been largely limited to intuitive designs. Topology optimization has recently been applied to the design of additively manufactured cold plates, but the designs are limited to two-dimensional optimization due to computational complexity. New tools are needed to enable the full potential of additive manufacturing to realize optimal three-dimensional designs. This STTR topic seeks innovative condenser designs enabled by metal additive manufacturing for efficient cooling of electronics. PHASE I: Design a compact, additively manufactured, metal heat exchanger for condensing a refrigerant with saturation temperatures below 35 °C (R134a preferred) using freshwater at 25 °C for heat rejection. Pressure drop on both the refrigerant and water side should be minimized to optimize efficiency. Verify feasibility using modeling and/or component demonstration. Perform rough manufacturing cost analysis. Develop a Phase II plan. PHASE II: Demonstrate a prototype R134a condenser using the concept developed in Phase I. The prototype should be able to reject 50 kW of heat to a fresh water system at 25 °C. Evaluate the efficiency of the prototype under various electrical and cooling loads and temperatures. Performance data, including heat transfer and pressure drop, shall be collected at a variety of flow rates (both refrigerant and water), temperatures, and entrance qualities. Validate analytic models developed in Phase I and evaluate scalability of design. PHASE III DUAL USE APPLICATIONS: Design and develop the next generation of compact, high efficiency condensers using the knowledge gained during Phases I and II. These heat exchangers must meet military unique requirements, e.g., shock and vibration. Advanced condensers developed here would be suitable for use in a variety of commercial applications, from hybrid vehicles to building air conditioning. REFERENCES: 1. X Zhang, R Tiwari, A.H. Shooshtari, and M.M. Ohadi, “An additively manufactured metallic manifold-microchannel heat exchanger for high temperature applications,” Applied Thermal Engineering, vol. 143, pp. 899-908 (2018). https://doi.org/10.1016/j.applthermaleng.2018.08.032 2. S. Sun, P. Liebersbach, and X. Qian, “3D topology optimization of heat sinks for liquid cooling,” Applied Thermal Engineering, vol. 178, 115540 (2020). https://doi.org/10.1016/j.applthermaleng.2020.115540 3. H. Moon, D. J. McGregor, N. Miljkovic, and W. P. King, “Ultra-power-dense heat exchanger development through genetic algorithm design and additive manufacturing.” Joule vol. 5, pp 3045-3056 (2021). https://doi.org/10.1016/j.joule.2021.08.004 KEYWORDS: thermal management; two-phase cooling; condenser; additive manufacturing; heat exchanger

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Develop an algorithmic tool for the seamless assessment of previous, current and short term forecast (0-24 h) atmospheric cloud characteristics such as ceiling, thickness, and optical depth for single and multiple overlapping cloud fields using machine learning methods to combine satellite based environmental monitoring (SBEM) analysis information, ground based remote sensing, and numerical weather prediction model fields. DESCRIPTION: Despite increasing complexity and accuracy of weather forecast models, tools for their use in diagnosing cloud and visibility characteristics are relatively unsophisticated. Many use cases assume a relatively static cloud field based on available satellite analysis data, climatological occurrence of cloud locations, or derived numerical weather prediction output (such as relative humidity fields). Using state of the art technology, this STTR topic seeks to bridge the gap between cloud analysis by satellite and forecasts from numerical modeling by using machine learning techniques and other data fusion capabilities to improve forecast uncertainty and cloud representation through a 24 hour forecast lead-time. Effort should focus on improved post processing of cloud characteristics in numerical modeling as well as techniques to seamlessly morph a true cloud analysis field from satellite into the predicted field. Implementation should take advantage of modern software strategies, including concise data presentation and intuitive user interface to display custom visualization of clouds from any 3 dimensional angle. PHASE I: Determine and demonstrate the technical capability to smoothly transition observed satellite observations of cloud cover into simulated cloud (or meteorological variables interpreted as cloud) forecasts. Work should identify methodological details to preserve the physical structure of observed cloud visibility characteristics, aesthetics and ease of interpretation, and incorporation of probabilistic information for metrics of uncertainty and/or alternate future scenarios. Skill with respect to aviation needs should be enumerated (e.g., accuracy of cloud ceilings, error in horizontal and vertical positioning, treatment of overlapping cloud layers) given validating data from ground lidar or other full atmosphere representation. Develop a final summary report, including literature review and overall conclusions/recommendations, to be presented at the end of this Phase. Develop a Phase II plan. PHASE II: Expanded technical development and validation of a robust prototype system of seamless historical, current, and future cloud state. Effort should be focused on 1) maturing complex machine learning algorithms that improve forecast representation of clouds given observed satellite cloud state (including advective schemes such as optical flow, clustering of cloud types, and texture analyses), 2) adding additional data sources and expanded spatial domain to prove application to any global location, and 3) iterating on accuracy and ease of user interface in display of cloud fields. Given the need to add many different satellite platforms and forecast model data, substantial subtasks on developing generic data reader capabilities and automated metadata generation and labeling are anticipated. While the code itself may need nominal high performance computing to run, output of prototype algorithm should be capable of being visualized on a standard laptop or cellphone with modest data bandwidth (such as by tiling). It is anticipated that the prototype data output and software package will be compatible with running from open source python data analysis libraries at the conclusion of Phase II efforts. Delivery of a prototype software package and final verification report is expected at the end of this Phase. PHASE III DUAL USE APPLICATIONS: This development will result in valuable knowledge and technology advances for the entire meteorological analysis and forecasting community, as well as downstream applications. Further follow-on Phase II efforts include expansion of observational and remote sensing datasets used to generate and validate the algorithmic tool, software refinements and hardening based on real-world operational constraints (such as data latency and drop outs, quality issues, etc.), and further tests of blending code to similar meteorological variables (such as atmospheric water constituents). DoD, civil, and private aviation will particularly benefit by having a state-of-the-art product aimed at understanding cloud visibility evolution at all stages of flight operations, from take-off through ferry and landing. Naval applications will particularly benefit by the significant increase in specific environmental data and available at any point where the Naval aircraft operations can occur. Other civil and commercial applications will benefit from enhanced data streams and software implementations for broad aviation and visibility applications, improved predictability in weather forecasts, and increased cross-over between civil and commercial satellite remote sensing activities. This effort has the potential to fill a data gap in all aspects of meteorological analysis as well as provide a foundation for additional data fusion opportunities. REFERENCES: 1. Mecikalski, John R., et al. "Probabilistic 0–1-h convective initiation nowcasts that combine geostationary satellite observations and numerical weather prediction model data." Journal of Applied Meteorology and Climatology 54.5 (2015): 1039-1059. 2. Veillette, Mark S., et al. "Creating synthetic radar imagery using convolutional neural networks." Journal of Atmospheric and Oceanic Technology 35.12 (2018): 2323-2338. 3. Wang, Chenxi, et al. "A machine-learning-based cloud detection and thermodynamic-phase classification algorithm using passive spectral observations." Atmospheric Measurement Techniques 13.5 (2020): 2257-2277. 4. Nachamkin, Jason E., et al. "Classification and Evaluation of Stable and Unstable Cloud Forecasts." Monthly Weather Review 150.1 (2021): 81-98. KEYWORDS: meteorology; weather; clouds; visibility; nowcasting; forecasting; numerical weather prediction; Satellite Based Environmental Monitoring; SBEM; satellite; remote sensing; data fusion; machine learning; optical flow; visualization; metadata; aviation

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Hypersonics; Nuclear OBJECTIVE: Formulate, implement, and validate finite-rate ablation models for hypersonic boost-glide vehicle thermal protection systems (TPS) such as 2D and 3D carbon-carbon (C/C) for accurate prediction of vehicle shape change, temperature distributions, and ablated species. DESCRIPTION: Boost-glide vehicles primarily rely on ablating TPS. Unlike strategic ballistic missiles, boost-glide weapons operate for a long duration in a range of altitudes and velocities where the rates of energy excitation, chemical reactions, ionization, and gas-surface interactions are comparable to the rate of fluid motion. This implies that the accuracy of legacy modeling approaches that assume equilibrium thermo-chemistry and equilibrium ablation are questionable for such systems. Recent numerical studies of graphite ablation at boost-glide relevant flight conditions have shown that equilibrium ablation models (i.e., B’ method) significantly over-predict nose-tip ablation compared to finite-rate ablation models [Ref 1]. Over the last decade, significant improvements have been made in the understanding and prediction of finite-rate processes in hypersonic flows by using ab initio quantum chemistry methods to generate potential energy surfaces (PES) for molecular interactions [Ref 1]. The PES can be used for the direct simulation of collisions between air species to obtain data for relaxation and reaction rates at specified conditions [Ref 2]. These data have enabled improved finite-rate chemistry models for computational fluid dynamics (CFD) simulations that accurately account for the vibrational energy state of the air species in the dissociation process [Ref 3]. Over the same time period, improvements have been made in the development of finite-rate carbon oxidation models based on molecular beam experiments of high-velocity O, and O2 species impacting high-temperature carbon material [Ref 4]. Such experiments enable the characterization of individual reactions and rate parameters as opposed to plasma wind tunnels experiments that measure the combined outcome of many reactions such that multiple combinations of parameters can be used to match the measured recession rate. Different finite-rate ablation models that produce comparable ablation rates can predict large difference in the ablation species such as CO, CO2, and CN. Very recently, molecular beam experiments that included the interaction with N and N2 species have provided the data needed for the development of construction of air-carbon ablation models relevant to hypersonic flight that include nitration in addition to oxidation [Ref 5]. Recent progress in the development of finite-rate carbon ablation models is encouraging, but these models need to be validated under a range of relevant hypersonic conditions and geometries for simple and relevant materials such as 2D and 3D C/C. This is needed as current molecular beam data has been obtained on highly oriented pyrolytic graphite (HOPG) and vitreous carbon as experimental models for the fibers and matrix, respectively, of C/C. It is also imperative to implement the new finite-rate ablation models in fully coupled CFD / material response codes to predict the TPS shape change, temperature distributions and ablated species. In addition, the assessment of TPS thermo-structural properties, surface roughness, and damage requires the simulation of the material microstructure. PHASE I: Formulate and implement finite-rate air-carbon ablation models in coupled CFD material response. Perform comparison against existing experimental data for simple materials such as HOPG and vitreous carbon. Quantities of interest include ablation rates (shape change), surface temperature, and ablated species. Criteria for success include the successful model implementation in material response code and validation. PHASE II: Refine the finite-rate ablation models and their implementation for relevant materials such as 2D and 3D C/C. The model refinement could include fundamental measurements on C/C to understanding the effect of the material microstructure on the reaction rates and parameters. Validation under a range of relevant hypersonic flow conditions in an arc-jet and or inductively coupled plasma torch (ICP) for nose-tip, leading-edge, and acreage are required to assess the accuracy of the ablation models. PHASE III DUAL USE APPLICATIONS: Improve the models and efficiency of the coupled hypersonic CFD / ablation toolset for prediction of shape change on complex geometries. The ablation toolset will ultimately be demonstrated on a relevant Navy weapons geometry via ground and/or flight test once a sufficient TRL is achieved. In the near term, this technology is geared toward military applications, but the methodologies for ablation model development and ablation toolset can be commercialized for commercial space vehicles using C/C TPS. Additional development for carbon-phenolic materials are also possible to expand the range of applications. REFERENCES: 1. G. V. Candler, "Rate effects in hypersonic flows," Annual Review of Fluid Mechanics, vol. 51, pp. 379-402, 2019. 2. R. L. Jaffe, D. W. Schwenke and M. Panesi, "First Principles Calculation of Heavy Particle Rate Coefficients," in Hypersonic Nonequilibrium Flows: Fundamentals and Recent Advances, Reston, American Institute of Aeronautics and Astronautics, Inc., 2015, pp. 103-158. 3. R. S. Chaudhry, J. D. Bender, T. E. Schwartzentruber and G. . V. Candler, "Quasiclassical Trajectory Analysis of Nitrogen for High-Temperature Chemical Kinetics," Journal of Thermophysics and Heat Transfer, vol. 32, no. 4, pp. 833-845, 2018. 4. S. Poovathingal, T. E. Schwartzentruber, V. J. Murray, T. K. Minton and G. V. Candler, "Finite-rate oxidation model for carbon surfaces from molecular beam experiments," AIAA journal, vol. 55, no. 5, pp. 1644-1658, 2017. 5. V. j. Murray, P. Recio, A. Caracciolo, C. Miossec, N. Balucani, P. Casavec and T. K. Minton, "Oxidation and nitridation of vitreous carbon at high temperatures," Carbon, vol. 167, pp. 388-402, 2020. KEYWORDS: Ablation; carbon-carbon; finite-rate; boost-glide; molecular-beam; oxidation; nitration

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy; Integrated Network Systems-of-Systems OBJECTIVE: Develop a haptic alert system (Digital Sidekick for Submarine Watchstander) to substantially accelerate information delivery timelines for critical alerts, which can be delayed or completely missed due to information overload. DESCRIPTION: Information overload is a critical factor negatively impacting the effectiveness of submarine watchstanders. Wrist or body worn haptic devices and haptic notifications have been shown to substantially shorten response times by immediately focusing attention on critical information or alerts being delivered by an artificial intelligence/machine learning (AI/ML) process designed to aid a watchstander. These devices are not currently deployed for submarine watchstations, Creating a process for accelerating delivery of critical information and alerts for submarine watchstanders can increase efficacy of numerous watchstations in time critical scenarios that will increase platform lethality, overall operational effectiveness, and platform survivability. This STTR topic seeks to deliver a haptic alert system that can be configured for a particular watchstation or individual to immediately alert and orient the person to critical information that requires urgent action. The principal objective will be to offer information delivery methods that cannot be missed in the most stressful scenarios, enabling a clear and focused response to the alert being provided. Key attributes for the project will include certainty of notification and watchstander awareness and understanding of information delivered which will result in measurable time savings for the required response. Ideal measure of effectiveness would include no missed alerts and substantially accelerated response times compared to scenarios without a haptic alert system. PHASE I: Identify technical design options to enable haptic delivery of alerts for a variety of submarine watchstations (e.g., sonar, electronic warfare, roving watchstanders, etc.). Technical solutions should address certainty of alert, durability and resiliency of devices and systems being utilized to provide the alert, and methods to reduce false alerts. Establish the feasibility of the concepts. Work to identify suitable testing locations for Phase II. PHASE II: Develop and deploy prototypes to suitable testing locations, including schoolhouse and platforms, to evaluate and determine impact of the prototype haptic critical alert and information delivery system(s). Work with users to define the most effective applications and use cases for most impactful technical applications for information delivery augmentation. PHASE III DUAL USE APPLICATIONS: The products and capabilities developed under this topic will transition to submarine watchstanders that can benefit most from the new information delivery approach. It is envisioned that multiple approaches will be viable with ADNS/SWFTS, Sonar, EW, Engineering Space and Forward Roving watchstanders obtaining clear benefit from improved information delivery and receiving critical alerts immediately through haptic notification. A dual use commercial application could also be pursued with similar haptic alert applications in a variety of scenarios involving commercial power generation or mechanical fabrication facilities. Due to the routinely quiet and vibration free environment on a submarine, it is uniquely suited to benefitting from haptic information delivery technology, but some stationary or low noise/vibration monitoring activities in the commercial sector could also potentially benefit from this technical approach. REFERENCES: 1. Giri, G.S.; Maddahi, Y. and Zareinia, K. “An Application-Based Review of Haptics Technology.” Robotics 2021, 10, 29. https://mdpi-res.com/d_attachment/robotics/robotics-10-00029/article_deploy/robotics-10-00029-v2.pdf?version=1612746858 2. Hayward, Vincent. “Haptics: A Key to Fast Paced Interactivity.” Center for Intelligent Machines, McGill University, Montreal, Quebec, Canada. https://www.sciencedirect.com/science/article/pii/B9780444506498500048 3. Dix, Annika; Schwendicke, Anna; Pannasch, Sebastian; Altinsoy, Ercan; Helmert, Jens R. “Chapter 7 - Augmented Perception and Interaction.” Tactile Internet Human-in-the-Loop, 2021, https://www.sciencedirect.com/science/article/pii/B9780128213438000186 4. Almeida de Souza, Gabrielle et al. “Evaluation of Visual, Auditory and Vibro-Tactile Alerts in Supervised Interfaces.” 20th Symposium on Virtual and Augmented Reality (SVR), 30 Oct. 2018. https://ieeexplore.ieee.org/document/8802446 5. “Haptic Technology: The Future of Engagement?” MassChallenge, 23 September 2021, https://masschallenge.org/article/haptic-technology KEYWORDS: Haptic; Perception; Multisensory; Feedback; Information Overload; Critical Alert; Interaction; Digital Sidekick; Watchstander Augmentation; Kinesthetic Feedback; Wearable Devices

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): FutureG; Microelectronics; Integrated Network Systems-of-Systems OBJECTIVE: Maximize radio frequency (RF) Switch performance in Nitrogen-polar (N-polar) Gallium Nitride (GaN) based on a high electron mobility transistor (HEMT) epitaxial layer structure capable of 4 W/mm power density. DESCRIPTION: RF switches are used in virtually all wireless systems. Losses or distortion in front-end switches directly impacts final system performance metrics. Traditional solid state RF switch performance is limited by the underlying switch transistor or diode device’s figures of merit including switch cutoff frequency, linear and saturation current density, and breakdown voltage. New switch device technologies including MEMS and phase change materials have shown higher performance but have drawbacks including lacking the switch cycle endurance needed for many applications, the difficulty of integration that adds losses which can negate some of their performance advantages, and for MEMs a greater vibration/shock susceptibility. N-polar GaN has recently shown record solid-state transistor switch performance metrics including a 1.7 THz switch cutoff frequency, and a straightforward path exists for monolithic integration of N-polar GaN power amplifiers (PAs) which are expected to also show record performance. Integration of an RF switch, power amplifier, and low noise amplifier (LNA) will enable low cost transceiver technology for applications addressing microwave to mm-wave systems. Recent results reported for N-polar GaN HEMT on Sapphire point to a very low-cost manufacturing for an integrated RF switch with a PA, and complete transceivers. Switch circuit application examples and metrics that can be pursued in this STTR topic: Ultra-broadband medium power low-loss switch: DC-100 GHz SPDT switch with > 2W 1dB compression point, > 10W off-state power handling, < 2 dB loss, 20 dB isolation Low-loss, high linearity, Ka-band antenna tuning switch: 26.5-40 GHz SP4T switch with 50 dBm IP3 High-power S-Ku band switch: 2-18 GHz SPDT switch with > 10W P1dB Alternate switch applications offered by proposers will be considered. PHASE I: Fabricate, characterize, and model switch device cells needed for the range of designs. Design and simulate switch circuits, using an epitaxy which supports power devices with 4W/mm and 25% power-added efficiency (PAE) at W-band. Characterize the switch device cell for loss, isolation, linearity, and power handling. Report on switch circuit design and simulation including loss, isolation, linearity and harmonic performance, and power handling for different applications. PHASE II: Refine models and fabricate switch circuits. Characterize switch circuits against the metrics and fabricate optimized designs based on specific applications proposed for Phase II. Implement fabrication process variations to correlate process parameters on field-effect transistor (FET) performance in a fab process flow suitable for integration with N-polar GaN PAs. PHASE III DUAL USE APPLICATIONS: Demonstrate an integrated RF switch with PA in N-polar GaN, and alternatively a complete transceiver including RF switch, PA, and LNA relevant to the metrics in the above Description and the Phase I goals. Dual use applications are expected to include commercial SATCOM, terrestrial backhaul communications for 6G and higher, Wi-Fi 6, and next generation wireless networks. REFERENCES: 1. Romanczyk, Brian et al, "Evaluation of linearity at 30 GHz for N-polar GaN deep recess transistors with 10.3 W/mm of output power and 47.4% PAE", Applied Physics Letters, vol.119, no.7, pp.072105, 2021 2. Romanczyk, Brian et al., ”Demonstration of Constant 8 W/mm Power Density at 10, 30, and 94 GHz in State-of-the-Art Millimeter-Wave N-Polar GaN MISHEMTs,” in IEEE Transactions on Electron Devices, vol. 65, no. 1, pp. 45-50, Jan. 2018, doi: 10.1109/TED.2017.2770087 3. Romanczyk, B. et al. “mm-Wave N-polar GaN MISHEMT with a self-aligned recessed gate exhibiting record 4.2 W/mm at 94 GHz on Sapphire.”2016 74th Annual Device Research Conference (DRC), Jun. 2016, vol. 2016,pp. 1–2. doi: 10.1109/DRC.2016.7548464 KEYWORDS: GaN; Gallium Nitride; High Electron Mobility Transistor; HEMT; Nitrogen Polar; RF Switch

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Hypersonics; Microelectronics OBJECTIVE: We will develop the flow theory, measurement technology, and estimation algorithms to enable non-intrusive aerodynamic state sensing for hypersonic flight control. The flow theory will describe measurable flow phenomena and their correlation to a weapon’s aerodynamic state. The measurement technology will sense the flow phenomena and produce correlated signals without devices that protrude into the flow around the weapon. The estimation algorithms will process the signal data to produce accurate and precise estimates of the weapon’s aerodynamic state. Collectively, the flow theory, measurement technology and estimation algorithms will be the foundation of a non-intrusive air data system that can operate in sustained hypersonic flight conditions. The system will produce aerodynamic state estimates at a rate sufficient for flight control. DESCRIPTION: Hypersonic flight conditions drive phenomena, e.g., chemical dissociation, material ablation, etc., that are generally not encountered in other flight regimes. Recent hypersonic flight experiments seek to understand phenomena such as boundary layer transition and its impact on heat transfer [Ref 1]. Ground-based hypersonic research has spurred successful investigations for non-intrusive flow measurement in a wind tunnel [Refs 2, 3]. Researchers have long recognized air data’s critical importance to controlled hypersonic flight. Driven by the promise of hypersonic flight sustained by air breathing propulsion, researchers investigated air data systems needed for highly coupled flight and propulsion control systems [Ref 4]. Despite the lack of an air-breathing engine, successful hypersonic flights with the X-15 rocket plane provided useful information on air data challenges. Even a sensor with 1% accuracy is not sufficient for control under the extreme pressures and temperatures associated with hypersonic flight. Researchers investigated a broad array of technologies ranging from pressure transducers to gas fluorescence with laser excitation as they worked to solve the air data problem for hypersonic flight [Ref 5]. Thus far, researchers have not identified a single technology capable of producing sufficient accuracy, precision, and bandwidth across the entire flight envelope of a hypersonic weapon, especially for weapons that cover subsonic, supersonic, and hypersonic conditions in a single flight. This raises the importance of state estimation algorithms that will need to fuse data from varying sensors over a broad range of conditions and aerodynamic phenomena. As flow diagnostic science and technology advanced for hypersonic wind tunnel experiments, researchers began to investigate these approaches for flight experiments. Researchers investigated electron beam fluorescence as a tool for non-intrusive flow diagnostics of the boundary layer in a hypersonic vehicle [Ref 6]. Researchers have also proposed using Raleigh Lidar to measure upstream density in concert with electron beam fluorescence to measure density and temperature of gas species within the boundary layer [Ref 7]. Given the potential and historical significance of using surface pressure measurements to estimate a vehicle’s aerodynamic state, researchers developed algorithms and an array of flush-mounted pressure sensors to estimate the aerodynamic state of an uncontrolled hypersonic flight experiment [Refs 8, 9]. A more recent flow visualization method that researchers have proven in the wind tunnel is Femtosecond Laser Electronic Excitation Tagging (FLEET), and they investigated FLEET as a measurement solution for a hypersonic air data system [Ref 10]. Researchers have demonstrated flow-imaging rates of 100 kHz using FLEET [Ref 11]. Given the extremely high speed of hypersonic vehicles, one might reasonable consider using only the inertial velocity vector to estimate the aerodynamic state. However, hypersonic vehicles go through large speed ranges as they accelerate to hypersonic speeds and decelerate while maneuvering. The difference between Earth-relative and Air-relative velocities can become non-trivial, and this large flight envelope ultimately requires hypersonic air data systems that also work below hypersonic speeds. Researchers addressed this challenge by investigating air data solutions built primarily on more complex algorithms rather than more complex sensors [Ref 12]. Continuing these scientific and technological developments, the objective is to develop the flow theory, measurement technology and estimation algorithms to enable non-intrusive aerodynamic state sensing for hypersonic flight control. Researchers have investigated and demonstrated numerous methods for hypersonic flow visualization in a wind tunnel, and they have made some headway towards translated these methods to flight vehicles. Successful performers will prototype a flight-representative, non-intrusive air data system with performance sufficient for flight control from subsonic through hypersonic conditions. Detailed modeling and analysis of the air data system, rigorous testing and model validation of subcomponents are critical first steps. Key system parameters and outputs are: • Air data measurement accuracy & precision • Air data measurement rate • Air data measurement time delay • Air speed • Aerodynamic angles • Air density and temperature • Robustness to hypersonic conditions, e.g., ablation, temperature, plasma, shocks, etc. • Robustness to weather and environmental conditions • Measurement range from subsonic through hypersonic Proposers must explicitly answer all of the Heilmeier questions to be considered for an award. PHASE I: The performer will work with Government and Industrial partners to establish a range of flight conditions for aerodynamic state sensing. Once the flight envelope is established, the performer will focus on evaluating current air data technology as well as investigating potential new approaches. New approaches may be driven by recent advancements in measurement techniques for flow diagnostics, modelling techniques for flow/structure interaction, high temperature materials for sensors, or any other technology that can produce a signal with a reliable correlation to a vehicle’s aerodynamic state. The performer will deliver the theory, modelling, and analysis of an air data system that functions from subsonic to hypersonic flight conditions. The theory will include a detailed explanation of the working principles behind the system, from flow dynamics to sensor dynamics. Modelling will include first order dynamics of the vehicle flow and sensors as well as algorithms for estimating a vehicle’s aerodynamic state. Analysis will include simulation results and predicted performance of the system based on the first order models. These deliverables will be in addition to the Navy’s standard Phase I deliverables listed in a contract award. A milestone for continuing to Phase II will be conceptual design calculations indicating that the proposed solution meets the established performance criteria. PHASE II: The performer will refine the theory of operation, increase model fidelity, and conduct higher order analysis to support the detailed air data system design. The performer will complete the engineering and detailed design for the concept developed in Phase I. Design details include physical and electrical interfaces, materials & devices, fabrication & assembly methods, signal conditioning electronics, embedded software, processors, power supply, cooling, etc. The analytical model developed in Phase I will be updated to include component models with sufficient complexity to predict the prototype system’s performance. The detailed explanation of the working principles behind the system will be updated to include implementation considerations such as quantization, sensor noise, sampling delays, filter dynamics, data fusion, etc. The model will be used to justify component requirements and predict the prototype system’s accuracy. The Phase II base scope will also produce a detailed test plan to validate both the system and the dynamic model. The test plan will cover everything from component level testing, ground testing, and flight testing. Ideally, flight testing would include hypersonic flight, but testing may be limited to supersonic flight. Test and validation for critical components will be included in the Phase II base period. Milestones required for the Phase II Option, if exercised, will be a detailed prototype design, validated test results for critical components, a detailed system model predicting acceptable performance, and an approved test plan. The Phase II Option will continue with any necessary component testing and fabrication of the prototype air data system. The milestone required for any Subsequent Phase II funding will be successful ground testing to demonstrate agreement between predicted and measured sensor dynamics. Subsequent Phase II awards will complete the test plan through flight test. PHASE III DUAL USE APPLICATIONS: Phase III will consist of four parts: Phase IIIa will refine the prototype design to ensure compliance with production requirements for vibration, shock, electromagnet interference, security, electrical & mechanical interfaces, etc. Three serialized production representative air data systems will be produced in collaboration with an airframe manufacturer. Calibration data will be collected and archived for all of the systems. System Serial Number 0 (SN0) will be subjected to environmental testing necessary to qualify for flight. Two milestones required for Phase IIIb funding are acceptable calibration data for all sensors and environmental test data to demonstrate that the production design meets requirements. Phase IIIb will integrate the system SN1 into a supersonic air vehicle in collaboration with an airframe manufacturer. System SN2 will be maintained as a spare. Flight test instrumentation will be installed to gather high rate sensor data as well as truth data from conventional sensors. A ground test plan will be developed, and ground testing will be conducted to ensure proper mechanical and electrical interfacing with the host vehicle as well as functionality of the air data system and flight-test instrumentation. The performer will develop a Flight Test Plan (FTP) for testing and evaluating the system. The FTP will include prescribed maneuvers, predicted responses, and pass/fail criteria for each test case. Highly dynamic maneuvers and variable atmospheric conditions will be included. Where possible, the FTP will include experiments to simulate phenomena present in hypersonic flight, e.g., ablative particulates, high temperatures, chemical dissociation, etc. The FTP will also specify equipment, team members and training requirements. A Flight Test Readiness Review (FTRR) will be conducted to get approval to execute the FTP. The milestone required for Phase IIIc funding is a successful FTRR. Phase IIIc will execute flight tests following the FTP. The flight experiments should produce data suitable for documenting the air data system’s accuracy and precision in an operational environment. The performer will assess the results and estimate the impact of hypersonic flight conditions on the system performance. The performer will draft a Flight Test Plan for conducting a hypersonic flight test of the air data system. The two milestones required for Phase IIId funding will be successful supersonic flight experiments with simulated hypersonic flight phenomena and an approved FTP for a hypersonic flight test. Phase IIId will execute the hypersonic FTP. The FTP will include vehicle integration, flight test instrumentation, telemetry, ground testing, training, and execution of the flight experiment. The milestone for a successful Phase IIId will be hypersonic flight data demonstrating the efficacy of the air data system as a flight control sensor for precise, accurate, and high rate measurements of a hypersonic vehicle’s aerodynamic state. REFERENCES: 1. Leyva, I. “Introduction to the Special Section on the Boundary Layer Transition (BOLT) Flight Experiment”. Journal of Spacecraft and Rockets. Vol. 58, No. 1, Jan – Feb 2021 2. Boutier, A. (Ed.). (2012). New trends in instrumentation for hypersonic research (Vol. 224). Springer Science & Business Media. 3. Brooks, J. M., Gupta, A. K., Smith, M., Marineau, E. C. “Development of Non-Intrusive Velocity Measurement Capabilities at AEDC Tunnel 9”. AIAA 2014-1239. 52nd Aerospace Sciences Meeting. 13-17 January 2014. National Harbor, Maryland. https://doi.org/10.2514/6.2014-1239 4. Kang, B. H. Air data and surface pressure measurement for hypersonic vehicles. Master of Science Thesis, Massachusetts Institute of Technology, 1989 5. Hattis, Philip. “Hypersonic Vehicle Air Data Collection: Assessing the Relationship Between the Sensor and Guidance and Control System Requirements”. 1990 American Control Conference [ACC 1990], May 23, 1990 - May 25, 1990, San Diego, CA, United States 6. Cattolica, R., Schmitt, R., Palmer, R. “Feasibility of non-intrusive optical diagnostic measurements in hypersonic boundary layers for flight experiments”. AIAA 28th Aerospace Sciences Meeting. 1990, January, p. 627 7. Mohamed, A. K., Bonnet, J. “Advanced Concept for Air Data System using EBF and Lidar”. Flight Experiments for Hypersonic Vehicle Development, pp. 16-1 - 16-32. 2007. Educational Notes RTO-EN-AVT-130, Paper 16. Neuilly-sur-Seine, France. https://apps.dtic.mil/sti/citations/ADA476499 8. Bode, C., Eggers, T., Smart, M. “Numerical Generation of a Flush Air Data System for the Hypersonic Flight Experiment HIFiRE 7”. New Results in Numerical and Experimental Fluid Mechanics VIII. Notes on Numerical Fluid Mechanics and Multidisciplinary Design. Vol 121. Springer, Berlin, Heidelberg. 2010. https://doi.org/10.1007/978-3-642-35680-3_13 9. Razzaqi, S. A., Bode, C., Eggers, T., Smart, M. K. “Development of functional relationships for air-data estimation using numerical simulations”. 18th Australasian Fluid Mechanics Conference. Launceston, Australia. 3-7 December 2012. 10. DeLuca, N. J. “Femtosecond laser electronic excitation tagging (FLEET) for a hypersonic optical air data system”. M.S.E. Thesis, Princeton University, Department of Mechanical & Aerospace Engineering, June 2014. 11. DeLuca, N. J., Miles, R. B., Jiang, N., Kulatilaka, W. D., Patnaik, A. K., & Gord, J. R., “FLEET velocimetry for combustion and flow diagnostics”. Applied Optics, 56(31), 8632-8638. 2017. 12. Nebula, F., Ariola, M. “A Hypersonic Application of the Fully Sensor-Less Virtual Air Data Algorithm”. AIAA 2018-1350. 2018 AIAA Guidance, Navigation, and Control Conference. January 2018. KEYWORDS: Hypersonic flight; flight control; air data; aerodynamic state estimation; conformal sensors; high temperature sensors; in situ hypersonic flow measurement

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy; Integrated Network Systems-of-Systems The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: Develop enabling technologies for providing high data rates and precise position, navigation, and timing services with high assurance and reduced hardware/software complexity by leveraging functional synergies of navigation and communication and their hardware/software similarities. DESCRIPTION: With the growing demand for high communication rate and navigation accuracy, different approaches for integrating the navigation and communication system have been explored for next-generation navigation and communication applications. If successful, a prospective integrated design could provide improved utilization of the spectrum and orbit resources by sharing the spectrum for navigation and communication. Moreover, it would reduce hardware/software complexity and power consumption by sharing radio frequency (RF) front end and signal processing unit, which are common to both communication and navigation. Also relevant is that it would leverage functional synergies of communication and navigation to improve the positioning speed via higher communication rate and alleviate the signal synchronization burden via timing information. However, the key challenge is to meet different requirements, namely high data rate and precise and trustworthy positioning/timing, with a single signaling system. Most previous efforts have explored these requirements in isolation. Navigation and communication functions are implemented independently without deep integration, and the spectrum resources are used separately. Furthermore, the message authentication mechanisms for secure and trustworthy satellite navigation and communication are implemented in isolation. The isolated design inevitably results in a waste of radio resources, increased hardware/software complexity, and degradation of network performance. This topic solicitation seeks a proof of concept to meet all the communication, navigation, and authentication requirements in a single design framework. Signaling solutions that provide: i) high data rates with low transmission power, ii) trustworthy position, navigation, and timing services with reduced hardware/software complexity and power consumption, and iii) reduced spectrum usage, are desirable. Solutions that are backward compatible with the existing navigation system, i.e., providing navigation services with the existing navigation receiver without any modification, are of interest under this call. Signal designs that support various services for users with different data rates, are also of interest. Theoretical performance analysis is highly encouraged as it can provide important guidance and insight for optimum system design. PHASE I: Identify and explore options for the integration of navigation, communication, and authentication, conduct trade analysis and simulations, define operating concepts, and provide justification for proposed solutions. Integrated solutions should offer potential advantages over state-of-the-art and demonstrate technical feasibility. PHASE II: Develop prototype hardware and software and demonstrate a proof of concept for trustworthy navigation and communication services. Evaluate the data transmission rate, navigation accuracy, and authentication error rate in the presence of spoofing attacks to support instantiations and deployments of the proposed concept. PHASE III DUAL USE APPLICATIONS: Integrate with prospective follow-on transition partners to provide an improved operational capability to a broad range of potential Government and civilian applications such as non-dedicated positioning, navigation, and timing (PNT) services (e.g. through communications systems) as can be derived from the NASA-funded HelioSwarm flight experiment consisted of multi-satellite missions by flying a swarm of nine spacecraft (8 nodes, 1 hub) to make measurements at multiple scales simultaneously, in which a large hub is utilized for transport of the smallsat nodes to the mission orbit and data relay. Government organizations such as Air Force Research Laboratory and Space Systems Command could sponsor a government reference design for PNT over communications flight integration, in collaboration with small business and industry partners. Successful contractor technology demonstrations will inform the technical requirements of future acquisitions by Primes and subcontractors. REFERENCES: 1. S. Han, Z. Gong, W. Meng, C. Li and X. Gu, "Future Alternative Positioning, Navigation, and Timing Techniques" A Survey, "IEEE Wireless Communications, vol. 23, no. 6, pp. 154-160, December 2016; 2. Zou, Deyue, and Shouchuan Ma. & "Satellite Navigation and Communication Integration Based on Correlation Domain Indefinite Pulse Position Modulation Signal. "Wireless Communications and Mobile Computing 2021; 3. X. Xu, L. Li, M. Zhao, and C. Fan, "A flexible design of waveform for communication and navigation, "IEEE Wireless Communications and Networking Conference (WCNC), 2018; 4. Zou, Deyue, and Shouchuan Ma. "Satellite Navigation and Communication Integration Based on Correlation Domain Indefinite Pulse Position Modulation Signal. "Wireless Communications and Mobile Computing 2021; 5. Yin, Lu, et al. "A novel positioning-communication integrated signal in wireless communication systems. "EEE Wireless Communications Letters, pp. 1353-1356, 2019; 6. Wang, Yu, et al. "Integrated Communication and navigation for ultra-dense LEO satellite networks: vision, challenges and solutions "arXiv preprint arXiv 2105.08985, 2021; 7. Zou, Deyue, Xinyue Li, and Ruofei Ma. "A signal optimization strategy for next-generation navigation and communication integration applications. "Physical Communication, 2022; 8. Wang, Lei, et al. "LEO-augmented GNSS based on communication navigation integrated signal. "Sensors 19.21, 2019; 9. Hein, Guenter W. "Status, perspectives and trends of satellite navigation. "Satellite Navigation 1.1, 2020 KEYWORDS: Communications; navigation; authentication; trustworthy position, navigation, and timing services; reduced hardware and software complexity; low power consumption; reduced spectrum usage

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Biotechnology The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: The goal of this topic is the development of “soft” implantable, biocompatible and biodegradable sensors that can measure multiple biomarkers of interest continuously, and provide a signal that can be interrogated either with an external device or internally, as part of the implantable device itself. DESCRIPTION: Implantable sensors are emerging as a promising means to perform a wide variety of diagnostic and therapeutic functions. In these types of applications, the hydrogel-based biocompatible polymer matrix containing photosensitized molecule probes must be properly designed to accurately measure biomarker levels under the skin. The most noticeable example of a flexible micro-sensor was reported by Profusa with Lumee, a tissue implantable device for monitoring the levels of oxygen in the surrounding tissues [1]. Applications of such implantable sensors include monitoring of peripheral artery disease, wound healing, and muscle performance. Recently, implanted sensors were reported for detecting the presence of oral cancers [2], as well as for battery-less recording of deep brain neuropotentials [3]. Research advances in tissue-injectable biopolymer matrix continue to develop for more advanced applications. For example, implantable temperature-sensitive sensors for infection biomarkers such as pH, carbon dioxide and viscosity of synovial fluid were recently developed for early detection of prosthetic joint infections [4]. Overall, with technological advances in biocompatible material development, implantable biosensors will have the potential to improve the management of patient health and quality of life, increasing survival rates while reducing health care costs. To respond to this topic, the performer should design implantable sensors with components that will assemble into soft materials able to interact transiently with analytes of interest and provide a readable signal that allows analytical quantification over time. Soft materials are defined here as made of biological components (proteins, peptides, nucleic acids and the like) in combination with biocompatible and biodegradable polymers that offer an optimal environment for sensing, with no electronics or other hardware required to be implanted. These materials will be in the micro- or nano-size scale in order to be implanted with no compatibility issues and/or major inflammatory reactions. The end deliverable will detect at least two biomarkers of military relevance when implanted in a model system (animal, tissue model, organ-on-chip platform) or in human subjects. The sensors will be active for at least 24 h without any user intervention or regeneration steps to maintain sensor function. PHASE I: The performer should identify/design: i) biological components or systems that can interact with identified biomarkers and produce a readable signal to sense their physiological levels over time, and ii) biopolymers with properties allowing for implantation into soft body tissues. At the end of the Phase I effort, the performer should provide a detailed plan for building the sensor prototype, test it for selectivity, sensitivity and biodegradability and the models/platforms to be used for these tests. The performer should also provide a detailed assessment of the rationale for their design considering inflammatory response, biofluid access, reader function and biodegradability bioproducts toxicity. PHASE II: Multiple biological sensing components or systems should be incorporated into the implantable biopolymer formulation allowing for detection of at least two biomarkers of interest. The performer should investigate cross-reactivity and sensitivity of incorporated sensing components and demonstrate that the implantable biosensor can be used for simultaneous and continuous monitoring of at least two biomarkers of interest. The performer should utilize existing or develop new technologies allowing for the sensor’s signal interrogation either with an external device or internally, as part of the implantable device itself, with no electronics or other hardware required to be implanted. At the end of Phase II, the performer should demonstrate that the implantable sensor can be used for monitoring physiological level of at least two biomarkers of interest and produce signals that can be remotely detected and converted into biomarker quantifying units. PHASE III DUAL USE APPLICATIONS: The performer should test the functionality of the implantable sensor using animal models, tissue models or organ-on-chip platforms. The performer may conduct human studies. At the end of Phase III, the performer should demonstrate that the developed sensing device can be implanted into soft body tissues and can be used for continuous monitoring of at least two biomarkers of interest. The implantable device should be active for at least 24 hours, biocompatible (e.g., without production of toxic or immunological response), and biodegradable over time. The performer should assess marker options for medical use in different areas (tissue regeneration, a self-contained theranostics system, wound healing, etc.) and sports medicine (tissue regeneration/injury recovery, etc.). REFERENCES: 1. http://profusa.com/lumee/; 2. O.K. Hammouda and A.M.M. Allam, “Utilizing implanted antennas to detect the presence of oral cancers,” Res. J. Eng. Scien., vol. 3, pp. 22-27, Jul. 2014.; 3. A. Kiourti, C. Lee, J. Chae, and J.L. Volakis, “A wireless fully-passive neural recording device for unobtrusive neuropotential monitoring,” IEEE Trans. Biomed. Eng., vol. 63, pp. 131-137, Jan. 2016.; 4. Wijayaratna, U. N.; Kiridena, S. D.; Adams, J. D.; Behrend, C. J.; Anker, J. N. “Synovial Fluid PH Sensor for Early Detection of Prosthetic Hip Infections.” Adv. Funct. Mater. 2021, 31 (37), 2104124. https://doi.org/10.1002/adfm.202104124. KEYWORDS: implantable sensor; biomarkers; biodegradable; continuous sensing

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy; Space Technology OBJECTIVE: The objective of this topic is to design contact lenses integrated with sensitive sensors to monitor physiological parameters as an innovative tool for the detection of stress biosignatures in body fluids in extreme operational environments (e.g., the arctic [i.e., extreme cold temperatures], heat, exposure to unknown contaminants, directed energy radiation, etc.). DESCRIPTION: In recent years, contact lenses as flexible and wearable sensing devices have shown significant progress in identifying potential biomarkers related to human disease. However, there exists a giant leap in creating these contact lenses with sensor chips integrated with unique functionalities to accomplish non-invasive detection of physiological biosignatures. Recent technological advances in material science, microelectronics, artificial intelligence, and digital engineering have enabled contact lenses as promising sensing devices for non-invasive monitoring systems of human performance in stressful operational environments. Despite significant efforts, the use of smart contact lenses remains limited because of their mechanical biocompatibility, detection sensitivity, and challenging integration process. Many characteristics are required for the successful development of smart contact lenses. First, they must maintain a high degree of transparency within the visual field, including the electronic materials for the embedded sensors and circuitry. Second, smart lenses must be comfortable to wear daily without interrupting the wearer’s routine mission in stressful environments. This generates several challenges relating to substrate mechanical stiffness, biocompatibility, lens shape, and surface irregularities that, if not controlled, could lead to eye inflammation and irritation. This challenge requires a multidisciplinary approach that leverage many technologies including biomaterials, microfluidics, biosensor circuits, energy supply, data transmission, and display. All these electronic components must be sandwiched within the lens substrate to prevent harming the eye surface, but it also obstructs direct contact with the tear fluid. A potential solution in this case is to use microfluidic channels for tear sampling and transport. Similarly, it is necessary to use flexible and biologically stable electrode materials to display relevant information on smart lenses with wireless communication capabilities and stable power supply. The proposed topic on wearable contact lenses integrated with biosensors can provide real-time noninvasive monitoring of physiological parameters and increase combat effectiveness in Airmen without interrupting or limiting the wearer’s motions. The biosensor components as well as the contact lens should be made of a transparent, opaque, flexible, and biocompatible material to be placed around the healthy pupil without obstructing the field of vision. The proposed contact lens designs must overcome the limitations of current contact lens sensors by continuously monitoring multiple analytes, such as the stress biosignatures cortisol and dehydroepiandrosterone (DHEA), without obstructing the user’s field of vision. PHASE I: A transparent sensor platform will be designed and fabricated to detect a panel of biomarkers (e.g., oxygen, glucose, cortisol, lactate, urea, etc.). Sensor components and their connections must be protected from mechanical deformations due to the soft and stretchable nature of the contact lens. The success for the first phase of this project would be to provide a proof-of-concept for the proposed prototype, demonstrating its multi-functional sensing ability with wireless and battery-free operation. The key deliverables are proof of concept data, specific detection of stress biosignatures, and an initial proof of concept prototype. The final report consisting of a detailed description is required to determine if the result of Phase I feasibility technology is currently at an acceptable stage. PHASE II: The work completed in Phase II should demonstrate the successful operation of a contact lens prototype with integrated sensor components wireless communication capabilities. The biocompatibility data should be conducted using in vitro or in vivo models to demonstrate the safety of the contact lens without producing toxicity. The smart lens must be comfortable to wear on daily basis without interrupting the routine mission. The contact lens substrate, mechanical stiffness, lens shape, and surface irregularities should be considered very carefully to not produce any inflammation or irritation to the human eye. The deliverable is the functional smart contact lens sensor with a wireless communication capability to transmit information collected from contact lenses to a receiver for analysis. PHASE III DUAL USE APPLICATIONS: Phase III should demonstrate dual use primarily for military applications in the field. A wearable contact lens integrated with biosensors must provide real-time noninvasive monitoring of physiological parameters (e.g., cortisol, DHEA, oxygen, glucose, lactate, etc.) and increase combat effectiveness in Airmen without interrupting or limiting the wearer’s motions or obstructing their vision. The second application is for commercialization to use to detect key biomarkers for diagnostic and clinical purposes. REFERENCES: 1. 1. S. Lee, I. Jo, S. Kang, B. Jang, J. Moon, J. B. Park, S. Lee, S. Rho, Y. Kim, B. H. Hong, ACS Nano 2017, 11, 5318.; 2. G. Z. Chen, I. S. Chan, L. K. Leung, D. C. Lam, Med. Eng. Phys 2014, 36, 1134.; 3. M. Falk, V. Andoralov, M. Silow, M. D. Toscano, S. Shleev, Anal. Chem. 2013, 85, 6342.; 4. C. Jordan, Building An Electrochemical Contact Lens Biosensor, https://commons.pacificu.edu/work/4c43dcb4-a05a-42a9-ab10-458b6b338467 2016; 5. Olgun, C.-C. Chen, J. L. Volakis, IEEE Antennas Wirel. Propag. Lett. 2011, 10, 262.; 6. Banbury, Linda K. Stress Biomarkers in the Tear Film https://researchportal.scu.edu.au/discovery/delivery/61SCU_INST:ResearchRepository/1267165460002368?l#1367455280002368 KEYWORDS: Contact lens; Stress biomarkers; Biosensors

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Hypersonics; The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: High temperature resistant Thermal Protection System (TPS) materials and structures, including their means of supply, are critical to the success of new hypersonic weapons and related U.S. defense modernization priorities. Key to their success is increased domestic production capacity, affordability, and supply chain resiliency. Hypersonics TPS applications of particular interest include boost glide vehicle acerage, leading edge, nosetip, and control surfaces as well as similar materials and supply chains of importance to the production rocket motors and other re-entry systems. Supply chain resisancy concerns include foreign reliance, single point of failure supply, obsolesence, long-lead times, and low manufacturing yields). The Defense Logistics Agency (DLA) seeks to provide responsive, best value supplies of related materials consistently to our Department of Defense (DoD) customers and other DoD stakeholders. DLA continually investigates diverse technologies for new or improved materials, more efficient means of their production, and more competitive domestic supply chains which would lead to the higher levels of innovation in current and future weapon systems combined with benefits to other commercial and government technology applications. Advanced technology demonstrations for increasing production capacity, affordability and supply chain resiliency for high temperature resistant TPS and related materials and processing are of high interest to DoD. These areas of materials and manufacturing technologies provide potential opportunities toward achieving breakthrough advances for national defense. Proposed efforts funded under this topic may encompass diverse TPS materials and processing at any level that will result in increasing production capacity, affordablity, and supply chain resiliency. Research and Development (R&D) efforts selected under this topic shall demonstrate and involve a degree of risk where the technical feasibility of the proposed work has not been fully established. Further, proposed efforts must be judged to be at a Technology and/or Manufacturing Readiness Level (TRL/MRL) 6 or less, but greater than TRL/MRL 3 to receive funding consideration. TRL 3. (Analytical and Experimental Critical Function and/or Characteristic Proof of Concept) TRL 6. (System/Subsystem Model or Prototype Demonstration in a Relevant Environment) DESCRIPTION: DLA R&D is looking for domestic capabilities and capacity that demonstrates new or improved high temperature resistant TPS materials, processing, and supply chains that increase domestic defense industrial base production capacity, affordability, and supply chain resiliency for hypersonic systems and other defense programs that depend on similar materials (e.g., other conventional weapons, strategic programs, and space systems). R&D tasks include identifying, developing, and demonstrating new and/or improved high temperature resistant TPS materials and production processes that support this topic area’s objecitives for increasing production capacity, affordablity, and supply chain resilieancy. Related areas of interest include materials, processing and fabrication of TPS components and structures as well as their various consitutent materials and processes (e.g., fiber reinforcements and their precursors, woven textiles and complex preforms, matrix precursors and prepreg, rapid densificiation, heat treating, additive manufacturing, production automation of weaving and prepreg application, and oxidation resistant coatings). PHASE I: PHASE I: Not to exceed a duration of 6 months and cost of $100,000. Determine, insofar as possible, the scientific, technical, and commercial feasibility of the TPS concept. Include a plan to demonstrate the innovative TPS materials process and/or discrete TPS parts or structures manufacturing and address implementation approaches for near term insertion into the manufacturing of relavant DoD hypersonic systems and/or related subsystems, components, parts, or related material supply chains. Collboration with a qualifying Research Institution (RI) is required for Small Business Technology Transfer (STTR) projects. Collboartion with a relavant DoD Component organzation (e.g., DoD lab and/or defense system program office) and one or more relavant DoD weapon system supply chain participants or other suitable organization is highly desirable. PHASE II: Not to exceed a duration of 24 months and cost of $1,000,000. The expectation is to develop a solution to the System/Subsystem Model or Prototype Demonstration in a Relevant Environment level, (TRL 6). Validate the feasibility of the innovative process by demonstrating its use in the production, testing, and integration of items, and/or materials and processes, for DLA and key DoD stakeholders. Validation would include, but is not be limited to, prototype quantities, data analysis, laboratory tests, system simulations, operation in test-beds, or operation in a demonstration system. A partnership with a current or potential supplier to DoD or other suitable partner is highly desirable. Identify commercial benefit or application opportunities of the innovation. Innovative processes should be developed with the intent to readily transition to production in support of DoD and its supply chains PHASE III DUAL USE APPLICATIONS: TPS technology transition via successful demonstration of a new material, processing or fabriaction technology. This demonstration should show near-term TPS application to one or more DoD systems, subsystems, components, or their related material supply chains. This demonstration should also verify the potential for enhancement of increased TPS producton capacity, affordablity, and supply chain resilancy. Private Sector Commercial Potential: TPS materials and manufacturing improvements, including development of domestic manufacturing capabilities, increased capacity, and affordability, have a direct applicability to diverse defense system technologies. Material manufacturing technologies, processes, and systems have wide applicability to the defense industry including air, ground, sea, space, and related defense technologies. Competitive material manufacturing improvements should have leverage into private sector industries as well as civilian sector relevance. Advancements in high temperature resistant materials, processing, and supply chain resiliency will benefit the defense industrial base and key weapon systement development, production, and sustainablity, as well as afford spin-off opportunities to civilian and other commercial sectors that depend on associated technogies and their innovatoins. REFERENCES: 1. Affordable Hypersonic Missiles for Long-Range Precision Strike https://www.jhuapl.edu/content/techdigest/pdf/V20-N03/20-03-White.pdf 2. Increasing Production Is Important for Hypersonics, Defense Official Says: https://www.defense.gov/News/News-Stories/Article/Article/2927403/increasing-production-is-important-for-hypersonics-defense-official-says/ KEYWORDS: Hypersonics, Thermal Protection Systems (TPS), aeroshell, leading edge, control surfaces, nose tips, high temperature resistant materials (e.g., carbon/carbon, ceramics, ablative phenolics, composites, metals and alloys); materials and processing (e.g., fiber reinforcement, matrix precursors, woven textiles and preforms, prepreg, rapid densificiation, heat treating, additive manufacturing, manufacturing automation, and oxidation resistant coatings); and structures fabrication.