Abstract: Target value detection for an unmanned aerial vehicle is described. The unmanned aerial vehicle includes a first transducer that transmits a first ultrasonic signal and receives a first ultrasonic response and a second transducer that transmits a second ultrasonic signal and receives a second ultrasonic response. The second transducer has a wider beam pattern than the first transducer. Determinations are made as to whether either or both of the first or second ultrasonic responses includes a target value within range areas associated with the respective beam patterns of the first and second transducers. A confidence value is generated based on the determinations. The target value is reflected from an object and the confidence value indicates a likelihood of a position of the unmanned aerial vehicle with respect to the object.

Abstract: A fluid impermeable transducer includes an assembly of a transducer head and a casing, and an actuator disposed in the casing rearward of the back of the transducer head and operable to transmit acoustic energy through the transducer head. The transducer head and casing define a working portion of the transducer that is fluid impermeable.

Abstract: A dual element time-of-flight diffraction (TOFD) transducer assembly (10) for use in detecting an anomaly (78) in a test piece (70), the transducer assembly (10) comprising: a first transducer element (35) a configured to transmit ultrasonic signals (85a) to the test piece (70), and a second transducer element (35b) configured to receive diffracted ultrasonic signals (85b) from the test piece, wherein the first and second transducer elements (35a, 35b) are housed within a common housing (15), the housing (15) also forming part of the transducer assembly (10).

Abstract: A CVG having first and second degenerate resonator modes with each a damping rate; drive circuits for causing the resonator to oscillate in the first and second modes in response to first and second drive signals; first and second sense circuits for generating first and second sense signals in response to the resonator oscillating in the first and second modes; a signal processing circuit having control loops for generating the first and second drive signals based on the first and second sense signals; and first and second damping feedback circuits for generating first and second damping feedback signals proportional to the first and second damping rates; an adding the damping feedback signals to the first and second drive signals.

Abstract: An airborne acoustic vector sensor for simultaneously measuring triaxial particle acceleration in three dimensions and pressure includes a triaxial MEMS accelerometer sensitive to an Earth gravitational field. The airborne acoustic vector sensor includes one or multiple MEMS microphones sensitive to sound pressure and overlapping the accelerometer in frequency. The airborne acoustic vector sensor includes a solid body having a density approximating a density of air. The accelerometer is mounted in or upon the solid body. The airborne acoustic vector sensor includes a suspension system supporting the accelerometer and solid body within a framework.

Abstract: An automatic sensitivity adjusting analog ultrasonic sensor includes an ultrasonic transducer, and a front end adjustable gain amplifier that amplifies the received ultrasonic signal from the transducer. A processor generates a carrier signal and a heterodyning circuit combines the carrier signal and the amplified ultrasonic signal to form a modulated signal spectrum from which an audio spectrum signal is generated. The processor further monitors the amplitude level of the audio spectrum signal and executes an auto sensitivity adjustment algorithm that automatically adjusts the sensitivity (the gain) of the analog front end amplifier down if the amplitude is above a preset upper threshold or up if the amplitude is below a present lower threshold. The processor may also further monitors the amplitude level of the ultrasonic signal level directly from the front end adjustable gain amplifier and execute the auto sensitivity adjustment algorithm as required.

Abstract: Processes and systems described herein are directed to imaging a subterranean formation from seismic data recorded in a marine survey with moving marine vibrators. The marine vibrators generate random sweeps with random sweep signatures. Processes and systems generate an up-going pressure wavefield from measured pressure and vertical velocity wavefield data recorded in the marine survey and obtain a downgoing vertical acceleration wavefield that records source wavefields, directivity, source ghosts, and random signatures of the random sweeps. The downgoing vertical acceleration wavefield data is deconvolved from the up-going pressure wavefield to obtain a subsurface reflectivity wavefield that is used to generate an image of the subterranean formation with reduced contamination from source wavefields, directivity, source ghosts, and random signatures of the random sweeps.

Abstract: There is provided a more efficient method for manufacturing a three-dimensional shaped object. The method of the present invention comprises a successive formation of a plurality of solidified layers through a light beam irradiation, wherein the solidified layers are provided by a hybrid of combined systems of an after irradiation system and a simultaneous irradiation system, the after irradiation system being such that the light beam irradiation is performed after a formation of a powder layer, the simultaneous irradiation system being such that the light beam irradiation is performed while a raw material is supplied.

Abstract: A flexural disk transducer is located in a shell or enclosure primarily for underwater use. Compression chambers adjacent to the transducer capture sound from bands on the disk and waveguides are used to direct the sound forward along a single propagation axis. An acoustic delay line is built into one waveguide to compensate for phase differences between the bands.

Abstract: Devices capable of being disposed in a wellbore for outputting acoustical signals for monitoring downhole parameters are described. Receiving devices positioned remote from the devices and can receive the acoustical signals and determine the downhole parameters. The devices can output acoustical signals in response to fluid flow or otherwise.

Abstract: The disclosure, in one aspect, provides an apparatus that includes an acoustic transducer and a backing in contact with a side of the transducer. The backing includes substantially unidirectional fibers in a matrix of a material that has high shear wave acoustic attenuation. The fibers contact the side of the transducer at an angle configured to convert substantially all of the compressional waves that enter the backing for the transducer into shear waves, which shear waves are then attenuated by the matrix of the backing material.

Abstract: A hydraulic modulator provides a rectangular outlet from which water can be discharged across an outlet mouth. Spaced from the rectangular outlet across the outlet mouth is a rigid blade. Because water is effectively incompressible at the frequencies of interest a compliance chamber is provided along an interior side of the rigid blade. Mechanical compliance elements are provided within or adjacent to the compliance chamber which may be displaced to absorb and discharge mechanical energy from the flow of water. Water flow shifts back and forth relative to the interior and exterior sides of the rigid blade.

Abstract: An acoustic wave transducer includes at least one electroacoustic motor, a horn having an inner wall and an outer wall, a counterweight, and a hollow housing having an inner wall and an outer wall and at least one acoustic opening. The electroacoustic motor is connected to the horn and to the counterweight along an axis, and the electroacoustic motor is capable of exciting the horn at about at least one resonance frequency. The housing is connected to the counterweight and surrounds the motor and the horn, the outer wall of the horn being arranged opposite an acoustic opening of the housing, and the space between the inner wall of the housing and the inner wall of the horn defines a cavity that contains a fluid. The transducer includes acoustic attenuation elements connected to the outer wall of the housing in order to attenuate the emission and/or reception acoustic waves at the frequency at least in a direction transverse to the emission/reception axis.

Abstract: The systems described include a light-weight, low frequency (200 Hz-1000 Hz), broadband underwater sound sources that comprise an inner resonator tube with thin walls tuned to a certain frequency surrounded by a shorter, larger-diameter, lower frequency tuned outer resonator tube that has an acoustic source suspended off-center inside the inner resonator tube.

Abstract: A multilayer backing absorber for use with an ultrasonic transducer comprises an elemental multilayer having at least one metal layer and at least one adhesive layer, wherein the backing absorber is adapted to be coupled to a vibrating layer of the ultrasonic transducer.

Abstract: An acoustic transceiver assembly including a housing, an oscillator, and a blocking element. The housing has at least one inner wall defining a cavity. The cavity has a first end and a second end defining an axis of said acoustic transceiver assembly. The oscillator is provided in said cavity. The oscillator is provided with a transducer element, and a backing mass positioned adjacent to the transducer element. A blocking element is positioned inside the cavity and adjacent to the oscillator. The blocking element is adapted to restrain a portion of said backing mass at a first pressure to thereby restrain the backing mass from lateral movement relative to the axis of the acoustic transceiver assembly. The blocking element is also adapted to release the backing mass at a second pressure.

Abstract: A hydrophone for recording underwater sound includes a housing having an outer surface designed to serve as a boundary surface for an incident sound wave and at least one vibration sensor having a sensor surface for recording sound waves and for preparing a sensor signal. The sensor surface of the vibration sensor is in an opening of the housing. A hydrophone assembly includes a plurality of the hydrophones.

Abstract: A transducer device includes a coupling cavity, a first resonant element and a second resonant element. The first resonant element is coupled to the coupling cavity and configured to send or receive acoustic signals. The second resonant element is coupled to the coupling cavity and configured to modify a frequency response of the first resonant element via the coupling cavity.

Abstract: A hull-mounted sonar array is provided. The array comprises a linear arrangement of hydrophones disposed within a generally D-shaped housing. The D-shaped housing comprises a generally flat portion having a first and second end and a curved portion extending from the first end to the second end. The hydrophones are arranged along the generally flat portion of the housing, equidistant from the curved portion. The housing is mounted to the hull of a vessel by, for example, a marine adhesive.

Abstract: An electro-mechanical transducer is disclosed, which provides a wideband response by activating successive multiple resonant frequencies in a way which provides additive output between the resonant frequencies with reduced cancellation below the first resonance and means for controlling the response by reducing the voltage drive. A multiply resonant wideband high output transducer is disclosed.

Abstract: A sound absorbing structure is constituted of a housing having a hollow portion and an opening and a vibration member composed of a board or diaphragm. The vibration member is a square-shaped material having elasticity composed of a synthetic resin and is bonded to the opening of the housing, thus forming an air layer closed inside the sound absorbing structure by the housing and the vibration member. In the sound absorbing structure, when the lateral/longitudinal dimensions of the air layer and characteristics of the vibration member (e.g. a Young's modulus, thickness, and Poisson's ratio) are set such that the fundamental frequency of a vibration occurring in a bending system falls within 5% and 65% of the resonance frequency of a spring-mass system, a vibration mode having a large amplitude occurs in a frequency band lower than the resonance frequency of the spring-mass system, this improving the sound absorption coefficient.

Abstract: A housing for a phased array monostatic sodar system with a transducer array that emits and receives multiple generally conical main beams of sound along different primary axes. The housing includes one or more upwardly-directed sidewalls that define a volume between them that is open to the atmosphere at the top, to emit and receive the beams, and an upper lip at the top of at least one wall, defining a curved perimeter at the top of at least some of the volume that closely conforms to the shape of at least one main beam at the location of the lip. The sidewalls are lined with a non-woven fiber based sound-absorbing material.

Abstract: An acoustic energy source for imparting acoustic energy into the Earth's subsurface includes an electrically driven transducer coupled to a source of swept frequency alternating current. A tunable Helmholtz resonator is disposed proximate the transducer. In one example, the resonator has a tuning device configured to maintain a resonant frequency substantially equal to an instantaneous frequency of the alternating current. The tuning device includes an actuator coupled to a sleeve, wherein the sleeve is disposed over selected numbers of openings in a wall of a tube on the resonator. The transducer and the resonator are disposed in a wellbore drilled through rock formations. The wellbore has a plurality of layers of fluid therein, each layer thereof having a different density and/or viscosity.

Abstract: An acoustic projector which includes an outer shell formed of a reinforced epoxy resin having a longitudinal slot has an inner reinforcing liner formed of metal to reduce mechanical stress. The liner extends throughout the length of the outer shell and has a longitudinal slot aligned with the slot formed in the shell. An arcuate shaped driver is mounted along a portion of the I.D. of the metal liner and separated therefrom by insulation. In an alternate embodiment, the outer shell is formed of a plurality of overlapping layers of epoxy/graphite strips extending at various angles to increase the Z-axis stiffness.

Abstract: An acoustic transducer array and method of baffle construction is presented to provide an improved array for use in underwater installations. The array is presented wherein a significant majority of the acoustic energy receiving surface is formed by lightweight acoustic baffling material while still maintaining a fully functional, fully populated array. The acoustic baffle constructed is incompressible and suitable for deep water operation while demonstrating both improved acoustic performance and positive buoyancy when necessary. In addition, the invention eliminates the non-uniform element to element spacing that occurs between sub-panels in similar arrays.

Abstract: Improved sonar baffles and backings are disclosed. The sonar baffles and backings include a porous polymer. The baffles and backings can be produced by partial selective sintering of a polyamide powder. Baffles and backings in accordance with exemplary embodiments exhibit advantageous acoustic properties, and can be manufactured to complex geometric specifications without difficulty.

Abstract: A housing for a seismic sensing element (3) for use on the earth's surface comprises connecting means (5) for connecting the housing (3) to a support cable (2) so as to allow relative movement between the sensor housing (3) and the cable (2). This de-couples the sensor housing from the support cable, and improves the fidelity of the sensor. The connecting means (5) preferably comprises resilient connecting elements, to prevent the transmission of vibrations between the support cable and the sensor housing. The sensor housing (3) preferably has a flat base (1), so that there is good coupling between the sensor housing and the earth. Alternatively, the sensor housing can be fitted with a base member ((24a, 24b, 24c) that has at least one flat face (26, 26a, 26b, 26c).

Abstract: The present invention provides a method and apparatus for a segmented antenna system. The method includes determining an orientation of a first antenna, the first antenna including a plurality of segments for transmitting and receiving signals, determining a direction from the first antenna to a second antenna capable or at least one of transmitting and receiving signals, and selecting at least one of the plurality of segments of the first antenna using the determined orientation of the first antenna and the determined direction.

Abstract: A hybrid drive (HD) multi-mode pipe projector (MMPP) for use in underwater acoustic applications is provided. The HD MMPP is formed with an inner magnetostrictive drive motor nested within an outer drive motor. The inner motor is surrounded by a magnetic field generating coil winding. Preferably the inner drive motor is a Terfenol-D motor and the outer drive motor is a radially-poled piezoceramic drive motor. This nested configuration provides increased bandwidth and low-frequency extension to the MMPP design.

Abstract: An acoustic projector which includes an outer shell (8) formed of a reinforced epoxy resin having a longitudinal slot (14) has an inner reinforcing liner (20) formed of metal to reduce stress. The liner (20) extends throughout the length of the outer shell and has a longitudinal slot (22) aligned with the slot (14) formed in the shell (8). An arcuate shaped driver (10) is mounted along a portion of the I.D. of the metal liner (20) and separated therefrom by insulation (24).

Abstract: An ultrasonic sensor includes a transmitting device, receiving devices arranged in an array, and a circuit device. One receiving device is configured as a reference receiving device. The circuit device includes a reference signal generator and first and second synchronous detectors. The reference signal generator generates a reference signal by using a received signal of the reference receiving device. The first synchronous detector performs synchronous detection of a received signal of one of the receiving devices based on the reference signal to detect a distance to an object. The second synchronous detector performs synchronous detection of received signals of the receiving devices except the reference receiving device based on the reference signal to detect a direction of the object.

Abstract: A hybrid drive (HD) multi-mode pipe projector (MMPP) for use in underwater acoustic applications is provided. The HD MMPP is formed with an inner magnetostrictive drive motor nested within an outer drive motor. The inner motor is surrounded by a magnetic field generating coil winding. Preferably the inner drive motor is a Terfenol-D motor and the outer drive motor is a radially-poled piezoceramic drive motor. This nested configuration provides increased bandwidth and low-frequency extension to the MMPP design.

Abstract: An acoustic transducer array and method of baffle construction is presented to provide an improved array for use in underwater installations. The array is presented wherein a significant majority of the acoustic energy receiving surface is formed by lightweight acoustic baffling material while still maintaining a fully functional, fully populated array. The acoustic baffle constructed is incompressible and suitable for deep water operation while demonstrating both improved acoustic performance and positive buoyancy when necessary. In addition, the invention eliminates the non-uniform element to element spacing that occurs between sub-panels in similar arrays.

Abstract: The Invention is a reinforced plastic sonar dome having a low acoustical insertion loss combined with sufficient mechanical strength. Acoustical and structural fibers are stochastically mixed and formed into a blended yarn. The blended yarn is woven into a blended fabric. The blended fabric is ordered into a stack having multiple layers of blended fabric. The blended fabric is incorporated into a polymer resin while the polymer resin is in liquid form using a vacuum assist. The acoustical fibers and the vacuum assist modify the acoustical properties of the resulting composite sonar dome.

Abstract: A sonar dome having an acoustic array housed therein. A plurality of bubbles are generated within the fluid inside the sonar dome. The generated bubbles are of an amount and size to reduce the speed of sound within the sonar dome fluid. Reduction of the speed of sound within the sonar dome fluid effectively increases the aperture of the acoustic array. The bubbles can be generated from a gas source or electrolytically. Typically, each individual bubble is less than 0.01 mm in diameter to reduce bubble velocity in the fluid.

Abstract: Disclosed is an underwater projector projecting a sound underwater. The underwater projector includes a first disk-type resonator unit, a second disk-type resonator unit, and a central space. The second disk-type resonator unit is installed so that a central axis corresponds with that of the first disk-type resonator unit. The central space is set up between the first disk-type resonator unit and the second disk-type resonator unit, and water can enter the central space.

Abstract: A seismic streamer includes a jacket covering an exterior of the streamer. At least one strength member extends along the length of and is disposed inside the jacket. At least one seismic sensor is disposed in a sensor spacer mounted to the at least one strength member. The streamer includes means for retaining the at least one sensor spacer to the at least one strength member. The means for retaining provides substantial acoustic isolation between the at least one spacer and the at least one strength member.

Abstract: A plurality of actuators are provided at predetermined intervals on the reverse surface of a predetermined side wall of a swimming pool. When an electric signal corresponding to a sound to be propagated in the water is given to the actuators, the electric signal is converted by the actuators into a mechanical vibration signal to cause vibrations. The actuators are secured directly to the reverse surface of the predetermined side wall by an adhesive or otherwise, and thus the vibrations of the actuators are radiated as a sound in the water of the pool through the side wall.

Abstract: A method and apparatus for damping an ultrasonic transducer suitable for time of flight ranging and level measurement systems. The ultrasonic transducer comprises a damping component which absorbs vibrations in the transducer to reduce the ringing effect. The damping component is subjected to plasma etching to produce a surface which readily bonds to component(s) of the transducer. According to one aspect, the damping component is formed from an inert elastomer, such as silicone rubber, and the transducer component is made of stainless steel.

Abstract: An electromechanical device for generating elastic waves in a material medium such as the subsoil in a frequency range where the wavelengths of the waves generated are great in view of the dimensions of the device, and method of implementation. The device comprises one or more vibrators which are buried in the medium, associated with a control system. Each vibrator comprises at least one inertia mass (1), several plates (2, 3) providing mechanical coupling with the medium, electromechanical transducers (4, 5) connecting inertia masses (1) to plates (2, 3). A control system (7) applies to the various transducers (4, 5) respective control signals so that the resulting elastic wavefield generated in the medium by the device is preferentially oriented in one or more directions.

Abstract: A seismic sensor, has a case, a pre-charged, non-conductive membrane located between two plates that form a capacitor and accommodated inside the case, with one of the plates being immovable relative to the case and the other of the plates being movable relative to the one plate under the action of seismic activity of a medium in which the sensor is located, so that the capacitor produces an electrical signal responsive to the seismic activity, and a mass increasing element associated with the movable plate so as to increase mass of the movable plate and therefore enhance oscillations of the movable plate under the action of the seismic activity.

Abstract: A focal point reflector is used in conjunction with a dual heterodyne circuit to reduce reception nulls that can occur when performing ultrasonic measurements. The focal plane reflector is a flat non-porous or reflective material, such as printed circuit board (PCB) that is placed behind and in parallel with an ultrasonic array of piezoelectric transducers. In accordance with the invention, the addition of the focal point reflector to the array of piezoelectric array permits the reflection of ultrasonic energy that may “fall” between the crystals in the array and then back into the crystal elements.

Abstract: Methods and apparatus for suppression of wave energy within a fluid-filled borehole using a low pressure acoustic barrier. In one embodiment, a flexible diaphragm type device is configured as an open bottomed tubular structure for disposition in a borehole to be filled with a gas to create a barrier to wave energy, including tube waves. In another embodiment, an expandable umbrella type device is used to define a chamber in which a gas is disposed. In yet another embodiment, a reverse acting bladder type device is suspended in the borehole. Due to its reverse acting properties, the bladder expands when internal pressure is reduced, and the reverse acting bladder device extends across the borehole to provide a low pressure wave energy barrier.

Abstract: An electro-mechanical transducer is disclosed, which provides a wideband response by activating successive multiple resonant frequencies in a way which provides additive output between the resonant frequencies. A three mode wideband high output transducer is also disclosed along with an electro-mechanical feedback system which provides a smoothed response as well as array control under multiple element usage.

Abstract: The present invention provides a microfabricated acoustic transducer with suppressed substrate modes. The modes are suppressed by either thinning the substrate such that a longitudinal ringing mode occurs outside of the frequency band of interest or by applying a judiciously designed damping material on the backside of the transducer substrate.

Abstract: A shock wave source has a coil carrier, a coil, having a metallic membrane separated from the coil in insulating fashion for generating shock waves. The coil carrier is formed of a material that damps the formation and/or the propagation of audible acoustic waves in the generation of shock waves.

Abstract: A shock wave source has a coil carrier, having a longitudinal axis, a coil and a metallic membrane separated from the coil in insulating fashion for generating shock waves. The coil carrier has a generated surface, a first cover surface facing toward the coil and a second cover surface facing away from the coil. For reducing the low-frequency sound generation when generating shock waves, a cross-sectional area of the coil carrier intersected at a right angle by the longitudinal axis has a non-circular contour. A reduction of the audible sound generation when generating shock waves can also be achieved when the second cover surface of the coil carrier is non-flat.

Abstract: A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment.

Abstract: A microfabricated acoustic transducer with suppressed substrate modes includes a diaphragm containing an upper electrode suspended above a substrate containing a lower electrode; the substrate may or may not contain electronic circuits. The substrate modes are suppressed by either thinning the substrate such that a longitudinal ringing mode occurs outside of the frequency band of interest or applying a judiciously designed damping material that absorbs acoustic energy from the substrate on the backside of the transducer substrate, or by both thinning the substrate and applying the damping material. The damping material has an acoustic impedance that matches the acoustic impedance of the substrate and is lossy.

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.