Abstract: A method and system for acoustic treatment performance testing in a free-ld acoustic environment is provided. A sound source directs a gated acoustic pulse at an acoustic treatment. Acoustic pressures of the gated acoustic pulse and reflected energy from the acoustic treatment are measured from a location approximately in-line with the source and the acoustic treatment. This measurement location is at least one-half the wavelength of the frequency of interest away from the source and is at least a distance equal to (t*c/2) away from the acoustic treatment where t is equal to the duration of the gated acoustic pulse and c is equal to the speed of sound in the free-field acoustic environment. The acoustic pressures of the gated acoustic pulse and reflected energy are compared as an indication of performance of the acoustic treatment at a frequency of interest.

Abstract: A simple mechanical device is provided which generates acoustic signals at ne or more specified depths. The device consists of a spring loaded piston placed in a wall of a housing, the spring loading biasing the piston away from the housing. The piston is subjected to a pressure differential between the exterior and interior of the housing such that the piston moves against the spring force and into the housing as the pressure differential, corresponding to a depth of the housing beneath a water surface, increases. As the piston moves further into the housing, it contacts a series of latches, each latch being used to detain spring loaded striker. The latches are spaced along the travel path of the piston such that each striker is associated with a specific piston movement, or depth. When the piston contacts a latch, the striker is released and strikes against a ledge within the housing, creating one of the acoustic signals.

Abstract: An electric cable junction box assembly includes a main body having a hole herethrough. A junction box main connector assembly is fixed in the hole and is provided with electrical leads adapted to receive a main cable end connector. A junction box secondary connector assembly is fixed in a second hole in the body, the junction box secondary connector assembly being adapted to receive a secondary cable end connector. A wiring harness in the main body is connected to the junction box main connector assembly, and a branch of the wiring harness extends from a remainder of the wiring harness and is fixed to the junction box secondary connector assembly.

Abstract: The present invention relates to an intelligent personal underwater monitng system which recognizes when a swimmer is in trouble and transmits a warning signal. The system comprises a device worn by the swimmer which senses water pressure and transmits a first signal when a predetermined depth is passed by the swimmer. The system further comprises a device for receiving the signals generated by the device worn by the swimmer and a neural network processor for processing the signals and generating an output signal representative of whether the swimmer is in trouble and an alarm signal generation device.

Abstract: A system for deforming or actuating an elastomeric structure is described. he system includes a plurality of tubes joined to the elastomeric structure. The tubes extend in the direction of a desired strain to be applied to the elastomeric structure and are constrained from circumferential expansion. When a pressurized fluid is applied to the tubes, the tubes deform causing a like deformation of the elastomeric structure.

Abstract: A system for digitally demodulating optical hydrophone signals is provided. The system includes an optical hydrophone connected to an analog-to-digl converter and further connected to a digital signal processor. Within the digital signal processor, a basic demodulator has a first and second mixing tables, the first table operating at a modulating frequency, .omega., injected into reference legs of the hydrophone, and a second table operating at 2.omega.. The mixer frequencies are coherently mixed with the incoming acoustic signals received by the hydrophone. An automatic calibration circuit which adjusts the phase of the mixers is connected to the basic demodulator.

Abstract: A method for automatically classifying test images based on their similares with a dictionary of example target and non-target images. The method operates by receiving a test image and then initializing variables for an iteration count and for the linear expansion of the test image. The test image is then projected onto each one of the target and non-target images in the dictionary, wherein a maximum scaling coefficient is selected for each iteration. A residue is then generated, and the linear expansion of the test image is increased until a predetermined number of iterations have been performed. Once this predetermined number of iterations have been performed, the sum of the scaling coefficients belonging to the target examples in the dictionary is compared to the sum of the scaling coefficients belonging to the non-target examples in the dictionary to determine whether the image is a target signal or a non-target signal.

Abstract: A fluid pump and expandable energy storage device includes a substantially igid circular band, a substantially rigid central hub, a membrane fixed to the band and to the hub, the membrane being enlargeable by a fluid introduced into the device, and a plurality of rods interconnecting the band and the hub. The enlargeable membrane is adjacent the rods, such that enlargement of the membrane causes movement of the hub and portions of the rods away from a plane of the band. The movement causes twisting and bending of the rods, biasing the rods to return to their original positions upon release of the fluid. Upon such release, the membrane and the rods immediately return to their non-enlarged states, forcing the fluid out of the device at a high velocity.

Abstract: A simple, mechanical device is provided which produces an acoustic signal a specified depth. The device consists of a shear plug in an exterior wall of the device housing which prevents the movement of a spring biased piston. The plug is subjected to increasing differential pressure between the exterior and interior of the housing as the depth of the device beneath the water surface increases. At a known pressure differential, corresponding to a specified depth, the shear plug fails, allowing for the actuation of the piston. The spring biased piston strikes against a ledge in the device, creating the acoustic signal.

Abstract: A data acquisition system receives an analog input signal comprising a pllity of octavely-nested components including a base octave and a selected number of higher-level octaves, and transmits digital data words representative of each component over a channel. The data acquisition system includes a data transmission system and an interface. The data transmission controller generates transmission strobes signals defining a series of octave transmission cycles each associated with one of said octaves, each octave transmission cycle having a series of octave strobe states including at least one octave strobe state associated with the base octave and successively higher numbers of octave strobe states associated with successively higher-level octaves. The transmission strobe states associated with each octave are uniformly distributed during each octave transmission cycle.

Abstract: A system and method for ranking features by exploiting their relationship the Fisher projection space. The system ranks n features in a feature set using a design set comprising exemplars from each of M possible event classes of an associated feature-based classification system. A training set is created by randomly selecting exemplars from each of the M classes in the design set. A "smoothed" Fisher projection space for the training set is created by replacing the sample means and the within-class sample covariance matrix normally used in deriving a Fisher projection space with expressions for the mean vectors and covariance matrices derived from event class probability density function estimates. The angle between a given feature and the smoothed Fisher projection space is calculated for each feature in the feature set, and the features are then ordered by increasing numerical size of this angle.

Abstract: A polymer ejector system for reducing drag on an external surface of an urwater vessel includes a base portion mounted in an exterior surface of the underwater vessel, the base portion including an arcuate inner wall. A flexible lip portion is positioned above the base portion and spaced apart therefrom. The lip portion has an outer surface substantially coplanar with an outer surface of the underwater vessel, an arcuate inner wall, and is tapered at a distal end of the lip. This lip may be actively moved by means of MEMS deposited electrodes to control the passageway mentioned next. A passageway is formed between and defined by the inner wall of the lip and the inner wall of the base portion, such that the passageway terminates at the outer surface of the underwater vessel and substantially tangent thereto. The ejector may be constructed from single crystal silicon by so called MEMS (Micro-Electro-Mechanical Systems) methods.

Abstract: A platform for servicing of vertically positioned missiles in a ballistic ssile submarine. The platform includes a vertically inclined rail and a horizontal frame. In the frame there is a first element having a first and a second end superimposed over the inclined rail. This first element is movably mounted directly on the rail at the first end and movably mounted in vertically spaced relation above said inclined rail at said second end. At least one second element is spaced laterally from the first element to enclose a missile tube access opening. A vertical support means is also positioned in opposed relation to the inclined rail. The vertical support means is adjustable to the curved hull surface of the submarine to maintain the frame horizontal. The platform is constructed from a lightweight material such as aluminum, and it can be carried and assembled by two men for the efficient servicing of VLS equipped submarines and other similar vessels.

Abstract: A quadrifilar helical antenna is provided having feed points connected to e individual helical antenna elements through a spiral coupling path. The spiral coupling path additionally is wound contrarily to the winding of the helix. Moreover, each path has variable dimensions to provide impedance matching.

Abstract: The present invention provides an improved grapnel which permits towed ars to be retrieved more easily and with less chance of damaging the array. The invention includes a pair of U-shaped members attached to a center stock, the U-shaped members being attached in a perpendicular relationship to each other. A threaded rod connects each vertical portion of the U-shaped members to the center stock, and each row has a roller disposed thereon. The grapnel further includes a hub disposed on the center stock proximate the rollers and ramps respectively attached to each vertical portion of the U-shaped members, for guiding a towed array into engagement with the rollers.

Abstract: A shock absorbing device includes a base portion interconnected with a top ortion and layered with a shock absorbing material. The base portion includes a base mount bracket having a planar support member and upstanding integral bottom mounting plates oriented in a perpendicular relationship with respect to the planar support member, and a planar interconnecting plate member removably connected to the upstanding bottom mounting plates of the base mount bracket. The top portion includes a planar top plate, and a U-shaped interconnecting plate removably connected to the planar top plate.

Abstract: A test fixture for the simultaneous evaluation of a plurality of seals inding an outer tubular shell having a first terminal end and a second terminal end. A first bulkhead has interior and exterior sides to cover the first terminal end of the tubular shell and a second bulkhead has interior and exterior sides to cover the second terminal end of the tubular shell. A sleeve has a first terminal end and a second terminal end and is positioned inside the exterior tube. The sleeve may be segmented into two sections connected end to end. One end of the sleeve is fixed to a simulated pipe flange and sealed by a coaxial overlapping seal. The other end of the flange is connected to an adapted ring by a similar seal. Another such seal is used to connect the two segments of the sleeve.

Abstract: An improved method is provided for operating a continuous wave sonar syst At time of transmission, a plurality of acoustic pulses are transmitted one right after another. Each pulse has a unique frequency and is of a time duration that is approximately one second long. The pulses are characterized by a separation frequency representing a difference in frequency between numerically successive frequencies. However, the pulses are staggered with respect to frequency. In the preferred embodiment, each successively transmitted one of the pulses is separated in frequency from an immediately preceding transmitted one of the pulses by an amount greater than the separation frequency. These multiple pulses seperated in time and in frequency, reduce the effects of frequency speading caused by the medium, resulting in a sonar with enhanced detection performance.

Abstract: A hydrophone assembly for deployment on the bottom of a body of water is vided wherein a plurality of hydrophones are mounted in a spaced apart relationship about the circumference of a housing which is designed to hold signal processing electronics. Each hydrophone is constructed to detect a range of frequencies within a defined receive angle that extends outward from the circumference of the housing. A resonance absorbing material is interposed between the housing and the hydrophones to isolate each hydrophone from mechanical resonance. Tilt switches are connected to each hydrophone for automatically and independently selecting hydrophones to participate in the output of the hydrophone assembly based on the orientation of the hydrophones. Selected adjacent hydrophones define a continuous receive angle formed by combining the receive angle associated with each adjacent hydrophone. The continuous receive angle faces upward from the bottom of the water to include an angular portion of the surface.

Abstract: A wideband, low-profile, towable submarine antenna is provided. The antenna is formed with a metal cylinder having a longitudinal slot. The entire enna may be encapsulated in a tow body and towed horizontally on the surface of the water. The longitudinal slot is open at one end and closed, or shorted, at the opposite end. The location of the antenna feedpoint is placed along the slot so as to set up two sets of frequency resonances. This configuration provides two voltage standing wave ratio minimums, thereby extending the effective reception and transmission range over the entire military UHF frequency range (225-400 MHz).