The performance of many advanced underwater acoustic sensor systems is limited by unwanted noise caused by the turbulent boundary layer (tbl). the tbl may also excite unwanted noise and vibration (flow noise) in a variety of marine and aircraft vehicles. a significant amount of flow noise reduction… More

An integrated acoustic array and signal processing system will be developed for the detection, tracking and identification of rotarywing aircraft. the technique uses a rugged piezo-electric polymer sensor and a proprietary telemetry system. a commercially available array processor is used to perform… More

Atlantic applied research corporation has been developing a very high accuracy laser surface shape measurement system. it currently has the ability to scan a measurement laser beam in one dimension and measure the position of the surface of almost any object it strikes relative to a reference plane.… More

An analytical model of the response of fiber optic and piezoelectric polymer hydrophones to mechanical vibration, will be derived and compared with at-sea trial data. additional noise mechanisms such as thermal fluctuations or pyro-electricity will be examined. a design for low noise hydrophones… More

A low cost fiber optic telemetry system is proposed for towed arrays. a conventional piezo-electric hydrophone modulates an fet which in turn modulates an led. the light from the led propagates up a fiber to a photo-detector on the mother ship. a separate fiber is required for every channel.… More

A system for rapid measurement of effective dynamic properties of elastomeric parts (including finished parts for quality control) will be developed. this system will be microcomputer based and "user friendly" for use by nonspecialists in a manufacturing setting. it will also be a useful laboratory… More

Over the last 15 years detailed methods have been developed to predict the torsional and lateral vibration of propulsion gear trains using lumped parameter, distributed mass-elastic parameter and statistical energy analysis techniques. by improving the detail used for the propeller, shafting and… More

A novel active sonar is suggested wherein the cavitation noise of a ship's screws provides insonification of distant targets and a towed line array passive sonar provides the receiver of reflected signals. the underwater radiated noise source is continuous in frequency and time, and is of modest… More

The active sonars typically used on submarines operate at frequencies high enough to be difficult if not presently impossible to model accurately with finite element analysis. likewise beam and cylinder models provide inadequate representations of the high frequency behavior of plate and frame… More

A submarine mast or periscope which pierces the free surface generates a visually observable wake on the free surface which renders the submarine vulnerable to detection. it is proposed to investigate the feasibility of reducing this wake by a combination of active and passive flow control devices… More

It is proposed that a computer code be developed which will locate and deduce the signature of low frequency transients by sparce sonobuoy arrays. it will be assumed that we know the properties of the propagating medium and that it is horizontally stratified. the algorithm will have four parts: 1) a… More

Sound and turbulence generated by the interaction between the flow and structures in wind tunnels adds to the fan noise and establishes the lower limit of background noise. it interfaces with the measurement of acoustic radiation from test articles and the performance of transition experiments.… More

Atlantic applied research corporation has been developing a very high accuracy laser surface shape measurement system. it currently has the ability to scan a measurement laser beam in one dimension and measure the position of the surface of almost any object it strikes relative to a reference plan.… More

The development of low-cost, depth insensitive, closely matched acoustic sensors will be initiated. the most likely technology for these sensors is oil-back thin film poly-vinylidene flouride plastic. these can give a performance equivalent to current ceramic technology, but at an order of magnitude… More

So-called "fouling" of filtration membranes, which leads to diminished filtrate flux and altered solute rejection and selectivity with time, is attributable to buildup of surfacematerials. responsible mechanisms include boundary layer, gel and cake phenomena, and interactions of particles or soluble… More

A method is proposed for calculating the vertical and horizontal forces and moments developed by a ducted propulsor on a submerged vehicle operating at a small angle of attack. The key element of the computational method is the development of an equivalent actuator disk representation of induced… More

A new approach is proposed for oceanographic remote sensing with dual use applications in mine hunting, ocean bottom mapping, and sea floor remote sensing. the weaver is a sonar system intended to detect, localize, and classify seafloor bottom laying targets, discriminating man-made items from… More