Abstract: The present invention relates to a system for sensing the curvature of a towed hydrophone array and a curvature sensor used in the system. The system has at least two curvature sensors positioned along the length of the array. Each of the curvature sensors comprises a bend member which bends as the array bends, at least one optical fiber within the bend member, and at least one detection device embedded within the at least one optical fiber to detect a change in the strain in the at least one optical fiber.

Abstract: The calibration circuit is used with a differential input, monolithic integrated circuit preamplifier in a sensor system. The calibration circuit tests the integrity of the sensor, the preamplifier, and the wiring in the sensor system. The calibration circuit includes first and second calibration capacitors having different capacitances connected to the preamplifier input leads. A calibration signal source is connected between the capacitors. The capacitors are preferably implemented on the same integrated circuit as the preamplifier. In operation, a calibration signal of known amplitude is applied to the calibration circuit and the level at the preamplifier output is determined. The level at the preamplifier output indicates certain conditions relating to the integrity of the sensor and its wiring, for example, an open circuit condition or a short circuit condition.

Abstract: The present invention relates to a fiber optic rotation sensing device. The sensing device includes a stationary base, a rotatable member, and an optical fiber configured in at least one loop about the rotatable member. The optical fiber is secured to an exterior portion of the rotatable member and to the base. Rotation of the rotatable member causes a distortion of the at least one loop and a change in the intensity of the light passing through the optical fiber. The change in light intensity is measured to provide an indication of the degree of twist of the rotatable member.

Abstract: A system and method for a neural network is disclosed that is trained to recognize noise characteristics or other types of interference and to determine when an input waveform deviates from learned noise characteristics. A plurality of neural networks is preferably provided, which each receives a plurality of samples of intervals or windows of the input waveform. Each of the neural networks produces an output based on whether an anomaly is detected with respect to the noise, which the neural network is trained to detect. The plurality of outputs of the neural networks is preferably applied to a decision aid for deciding whether the input waveform contains a non-noise component. The decision aid may include a database, a computational section and a decision module. The system and method may provide a preliminary processing of the input waveform and is used to recognize the particular noise rather than a non-noise signal.

Abstract: A sonar system and method are provided to extract and identify information about a particular target illuminated by an active sonar system. The present invention utilizes a Volterra Series Expansion in conjunction with a least squares procedure to estimate channel and target responses, which may be linear or nonlinear. The system estimates the channel and target responses for different orders of the Volterra Series Expansion and then selects the order for which a minimum error is determined with respect to a measured acoustic return signal. The system requires as inputs only the excitation waveform and the measured acoustic return signal.

Abstract: A water tight shell joint for a super cavitating underwater vehicle is described. The shell joint includes a female member defining a first part of at least one slot for ejecting gas, a male member defining a second part of the at least one gas ejection slot, and at least one shim for adjusting the width of the at least one slot to obtain a volume of ejected gas sufficient to obtain a uniform cavity about the vehicle.

Abstract: An underwater acoustic transducer includes a set of formed substrates of piezoelectric polymer composite, the formed substrates having at least a first and second surface. Conductive electrodes are deposited on the first and second sides of the formed substrates. One surface of the substrate is bonded to an acoustically absorptive backing material. Either surface can be made to conform to a singly or doubly curved geometry. Electrodes deposited on these substrates may be continuous to form a single transducer element, or segmented to form sub-arrays of transducer elements.

Abstract: The present invention provides a method and apparatus for enhancing active sonar signal detection by estimating the channel/target response utilizing measured values of the excitation signals and received signals. A Wiener/Volterra series expansion for the excitation and received signals is used as a model, wherein a time invariant environment is assumed, thereby disregarding all random noise contributions. The Wiener/Volterra kernels are then determined in a nonlinear processor using a method of correlations which is designed to produce the kernels utilizing only measured white Gaussian excitation signals and received signals. The kernels can be used to give an optimum correlation between the excitation signals and the received signals.

Abstract: A distributed fiber strength member tow cable termination assembly (DTCTA) having a strength member termination area which is spaced from a signal conductor termination area, and which includes a seal area having a plurality of sealing members is disclosed. The strength member termination area preferably includes a strength member termination wedge having a curved outer face which allows for higher termination efficiency. The strength member termination area and signal conductor termination area are distributed, or separated, a predetermined distance by an interface section, for example a length of hose. The separation of the strength member termination area from the signal conductor termination area allows for several improvements in the DTCTA not possible in the prior art due to the previous need to terminate the signal conductors co-located with the strength termination member.

Abstract: Non-chromate solutions for treating and/or etching metals, particularly, aluminum, aluminum alloys, steel and titanium, and method of applying same wherein the solutions include either a titanate or titanium dioxide as a “drop-in replacement” for a chromium-containing compound in a metal surface etching solution that otherwise would contain chromium.

Abstract: A parametric sonar for use in a liquid medium includes a first signal generator which transmits a first acoustic signal and a second signal generator transmitting a second acoustic signal which interatct to produce a difference frequency signal at an interference region. A cavitation generator is provided to transmit a cavitation acoustic wave causing cavitation vapor bubbles in the liquid medium at the interference region. The cavitation vapor bubbles improve the efficiency of generating the difference frequency signal.

Abstract: An apparatus for launching an object in a fluid environment having a tubular member with a forward muzzle end, an opposed rearward end. The object is positioned in the tubular member. Ends of the tubular member are closed by expellable members. Flood valves are located on the expellable members and, on activation, allow flooding of the tubular member by external fluid. A propellant device and an object contact member are disposed within the tubular member. When the propellant device is activated, the object contact member moves the object. These actions are controlled by a control device which first causes the flood valves to enable fluid to flood the interior region. Next, the control device causes the expellable members to be expelled from the tubular member. The control device then causes the propellant device to generate gas in a predetermined manner launching the object from the tubular member.

Abstract: A circuit interrupter device protects a load circuit from excessive, or overloading levels of current, provides a visual indication of circuit overload and open circuit, and can be reset. A multi-metallic heat reactive strip is snapped by an overload current to open the load circuit and close a light emitter circuit having a current limiting resistor connected to an indicator lamp that provides a visual indication of the open circuit. The multi-metallic strip is manually reset via a push button to open the light emitter circuit and extinguish the indicator lamp and close the load circuit to reestablish operation therein. The circuit interruption device can be made utilizing currently available technology for miniature fusing in tight, confining spaces and/or assemblies that have unusual shapes that restrict access in automobile electrical systems, test instruments, domestic appliances or many other electronic/electrical circuits.

Abstract: An acoustic array deployment system and a method are provided. An optical fiber acoustic array has a first end coupled to a projectile housed onboard an underwater vehicle. A second end of the array is coupled to the underwater vehicle. The acoustic array is stored on a spool while the projectile is housed onboard the underwater vehicle. The projectile is launched from onboard the underwater vehicle in a gravitationally downward direction that is not aligned with the underwater vehicle's direction of travel. As a result, the acoustic array is paid out from the spool as the projectile is launched and then sinks. By establishing the line array's broadside beam in a direction that is away from the vehicle and approximately perpendicular to the vehicle's direction of travel, the relative angular difference between the underwater vehicle and target can be used to guide the vehicle towards the target.

Abstract: An underwater acoustic receiver sensor is disclosed that measure up to seven (7) quantities of acoustic field at a collocated point. The quantities measured by the acoustic receiver sensor are acoustic pressure, three orthogonal components of acoustic particle acceleration and three spatial gradients of the acceleration vector. These quantities are appropriately combined and provides for improved directivity of the acoustic receiver sensor.

Abstract: A hydraulically activated device for spacing plural towed lines includes a toroidal and inflatable tube member defining an aperture in an opening of the toroid shape. A plurality of connectors each secure a corresponding one of the plural towed lines to the toroidal and inflatable tube member. The toroidal and inflatable tube member is inflated with sea water to a predetermined volumetric configuration suitable to an operating speed range of the towed lines and upon inflation will space the towed lines in a three-dimensional arrangement therearound. A sheath may also be formed around the toroidal and inflatable tube member, the sheath being formed in cross section as a tear drop or similar streamlined shape.

Abstract: A system and method provides automatic monitoring of data representing the onset of, or occurrence of fault conditions for a submarine mast system. The system is separately programmable and transparently operable with respect to the mast host system that controls mast functions. In a preferred embodiment, a plurality of sensors are in communication with a microprocessor system to record data by time and date of the event. The communication of data from the sensors to the microprocessor is electrically isolated from control signal communications to mast components, and the sensors are further individually opto-isolated. The microprocessor may selectively transfer data on a time-shared basis over host system communication lines to an independent memory collecting submarine fleet data, as an aid in fleet-wide maintenance decision making.

Abstract: A multimode invariant processor is provided to simultaneously classify one or more patterns in multidimensional or in two dimensional “real world” images. The classification is invariant to a translation, a change in scale size and a rotation of a whole or partially hidden photonic image. The multimode invariant image processor comprises a retina portion, a nonlinear processing portion, a convergence processing portion and a classifier portion. The retina portion processes the photonic image to obtain an image data array of pixels and further process the array of pixels through a window difference network to obtain gradients of the image data. The neural directors of the nonlinear processing portion receive the gradients and generate respective feature vectors, which may have a greater dimensionality than the gradient information, to aid in discrimination between similar patterns in the image data.

Abstract: A method for maximizing the radiated power of a transducer, such as a sonar transducer, includes providing a transducer system comprising a transducer operating at a frequency f and having a radiating face, a tuning fluid having a density &rgr;1 and a speed of sound c1, a tuning plate having a density &rgr;p and a thickness t, and an external fluid having a density &rgr;2 and a speed of sound c2; and tuning the transducer to have a maximum specific acoustic resistance at the radiating face in accordance with the equation: [ ( 2 ⁢   ⁢ π ⁢   ⁢ f ⁢   ⁢ ρ p

Abstract: A supercavitation ventilation control system is disclosed and includes a vehicle body having a fore end and an aft end. A cavitator is fit to the fore end of the vehicle body, the cavitator generating a gas cavity around the vehicle body. A cavity control ring is slidably positioned at the aft end of the vehicle body, the cavity control ring selectively adjusting a terminal end of the cavity formed by the cavitator. A stop ring is adjustably positioned on the vehicle body forward of the cavity control ring for managing a reentrant jet generated by the cavity control ring. Each of the stop ring and cavity control ring are moveable by separate actuators and a single control system.