Abstract: A small boat or launch such as a motorized reinforced hull inflatable boat provides a platform for an acoustic source array of airguns. The array is made up as a ladder structure in which the airguns are disposed horizontally between vertical support and umbilical lines, preferably with their discharge ports in laterally offset or staggered relationship to minimize undesirable interactions between the acoustic transmissions released into the water by the sources and to help maximize the acoustic output of the array for a given array length. A structure stows the array on the boat for transport when the array is not deployed for use. If desired, the stowed array may be substantially enclosed by the hull of the boat. The stowage structure is preferable defined by a track or rails on the top of the deck. Umbilical cables attached to the array are translated, as by being wound on a drum and unwound therefrom, to deploy or retrieve the array over the stern of the boat.

Abstract: In order to optimize detection of targets from a broadband return, a multiplicity of narrow bands are matched-filter processed simultaneously in parallel. The band or bands which provide the best joint combination of target and propagation in response are used for target detection.

Abstract: In order to optimize detection of targets from a broadband return, a multiplicity of narrow bands are matched-filter processed simultaneously in parallel. The band or bands which provide the best joint combination of target and propagation in response are used for target detection.

Abstract: A small boat or launch such as a motorized reinforced hull inflatable boat provides a platform for an acoustic source array of airguns. The array is made up as a ladder structure in which the airguns are disposed horizontally between vertical support and umbilical lines, preferably with their discharge ports in laterally offset or staggered relationship to minimize undesirable interactions between the acoustic transmissions released into the water by the sources and to help maximize the acoustic output of the array for a given array length. A structure stows the array on the boat for transport when the array is not deployed for use. If desired, the stowed array may be substantially enclosed by the hull of the boat. The stowage structure is preferable defined by a track or rails on the top of the deck. Umbilical cables attached to the array are translated, as by being wound on a drum and unwound therefrom, to deploy or retrieve the array over the stern of the boat.

Abstract: A marine towed array has a plurality of tow bodies of positive buoyancy each containing a marine acoustic source, such as a vibrator source. Each tow body uses a reel containing an electro-mechanical tow cable connecting the sources, whereby reeling and unreeling of the cable, controlled from a towing ship, changes the spacing of the tow bodies. One of the tow bodies at an end of the array is attachable to the towing ship.

Abstract: An electrohydraulic pavement breaker system having cavities (28, 30) which are filled with hydraulic fluid (oil) or gas, and which provide mass spring system which is resonant at a frequency which is especially adapted for breaking and rubblizing concrete pavement. The resonant mass (18) is in impacting relationship with the pavement through a shoe (12), which shoe (12) may be part of an assembly which is pivotally mounted on the support structure (10) of the breaker and is vibrated with the mass (18) to repeatedly impact the pavement at the rate of the resonant frequency. An electrohydraulic control system is responsive to the motion and average position of the mass of the vibrator and controls the driving force so as to be at the resonant frequency of the mass spring system and have the amplitude and energy suitable for breaking the pavement.

Abstract: An acoustic transmission in an underwater environment having a spectrum (amplitude/frequency signature) of interest is generated by cyclically releasing energy which forms impulses which individually have spectral amplitudes principally near one end of the desired spectrum, but which impulses are repeated at a rate near the opposite end of the desired spectrum, which rate may be varied to smooth the spectral response. A multiplicity of impulses may be generated synchronously, the number depending upon the desired amplitude of the spectrum. A multi-port air gun having a stator with a series of ports, which are valved by a rotor coaxial with the stator provides the energy in the form of the release of compressed air bubbles. The rate at which the impulses are produced is controlled by controlling the speed of rotation of the rotor.

Abstract: A system for geophysical exploration uses a single source (30) which emits signals over multiple octaves. The source is driven by a composite sweep signal having two or more sweeps, one of which covers the lower octave (10) while the other sweeps cover the remainder of the bandwidth. The signals covering the lower portion are reduced in the case of a sweep which varies linearly with time in proportion to the square root of the ratio of the sweep rate of the signals covering the upper end to the sweep rate of the signals covering the lower end. The signals are transmitted simultaneously. Because of the composite sweep the same energy spectrum is transmitted as with a sine wave sweep which extends over the entire frequency band, while reducing the peak power and radiator displacement required at lower frequencies to maintain a flat spectrum. The size of the equipment can be reduced.

Abstract: An improved acoustic source array system is provided by the invention to generate acoustic signals underwater. The system has an array of acoustic signal sources, such as air guns, towable while underwater behind a surface vessel. The array includes a plurality of these sources, and spreader bar assemblies including these sources. The sources are attached by these assemblies at predetermined separation distances in the array. The spreader bar assemblies provide manifolds for storing and regulating energy, such as compressed air, to operate the sources. The array is connected to the vessel by an umbilical. The sources are controlled by a shipboard controller for firing the sources to provide acoustic signals underwater at selected times. The array may be towed from the ship with the flat side of the array assuming an angle of approximately 45.degree. or less with respect to a vertical axis. The flat side of the array includes a horizontal axis that is normal to the direction of tow.

Abstract: A pneumatic gun or air gun having a fast-acting sliding valve reciprocable between two axial positions to close or open intake and exhaust ports in a charge chamber in a housing. The sliding valve comprises a piston internal to the housing and may include a piston in a cylinder within and extending beyond the housing. The sliding valve has a sealing flange which forms a lip seal with an annular mating surface of the housing to close an exhaust port. Air accelerating from the gun may be radial from an equatorial exhaust port or may be axial from an end of the charge chamber. The charge chamber is provided with an intake port in selective communication with a source of pressurized gas, thereby to facilitate rapid charging rates. The intake port is closed when the exhaust port is opened by the sliding action of the valve member, and is opened when the lip seal is formed to close the exhaust port.

Abstract: A pneumatic gun having a fast-acting sliding sleeve valve member reciprocating between two axial positions, first to open an exhaust port for the explosive release of gas from a pressurized charge chamber in a stationary housing while simultaneously closing a pressurized intake port to said chamber, and then to close said exhaust port while simultaneously opening said pressurized intake port for recharging said charge chamber, all for the purpose of generating repetitive trains of impulsive sounds at a rapid rate with increased efficiency. The sliding valve member comprises a sleeve and may include a piston in a cylinder within the housing. The sliding valve member has a sealing flange which forms a lip seal with a stationary annular mating surface of the gun to close an exhaust port. A wall of the charge chamber is provided with an intake port in communication with a source of high-pressure gas.

Abstract: False target (reverberation, clutter, etc.) detection is suppressed in an echo ranging system (sonar or radar) in which target velocity and range are measured using a composite Doppler invariant-like signal having at least two segments, such as are present in a "rooftop" or "vee" HFM signal, such composite signal having an ambiguity function with two or more ridge lines of different slopes that intersect along the zero-velocity time axis. A bank of matched filters provides a distribution of outputs which has an ambiguity function-like character with intersecting pairs of ridge lines, the intersecting points of said pairs characterizing the range and velocity of the echo returns. This distribution is adjusted so that the intersecting ridge lines of each pair have equal and opposite slopes with respect to the time axis. In particular, fixed reverberators, which would have ridge lines intersecting on the zero-velocity time axis, would be symmetrical about this axis.

Abstract: A water gun seismic source for use in underwater environments has a sleeve valve (100) for opening a jet aperture (37, 101) to enable jets of pressurized water to be emitted for the generation of a seismic signal. The water is pressurized by a drive piston (3) which is reciprocated to a cocked position for pressurizing the water for the jets. A compressed air operated cocking mechanism (4, 7, 8, 76 or 110-199 or 200-260) is coupled to the piston for cocking it. The cocking mechanism may utilize cocking piston (7) slideable on a shaft (4) connected to the drive piston (3) which cocking piston is returned to a position where any load due to such cocking piston is decoupled from the shaft. The sleeve valve (100) may be biased to close the jet aperture ports (101) by compressed air and opened with high timing resolution when the pressurized water held back by the sleeve valve is applied to actuate it (via 40, 41, 50 & 43).

Abstract: In order to stress relieve exposed portions of plastic welds, and thereby reduce susceptibility of such welds to solvent-induced crazing and cracking, the welded parts are formed with flanges extending outwardly therefrom. These flanges are at least partially joined during welding, their adjoining surfaces providing at least a portion of the welded joint. After welding, the flanges are compressed in a direction transverse to their adjoining welded surfaces, the compression being of sufficient magnitude to exceed the yield strength of the flanges, thereby relieving stresses in the exposed portion of the welds. The flanges may be sheared, as by a blade which provides both transverse compressive forces and compressive forces in the direction of the adjoining welded surfaces. The flanges may be sheared through, so as to enable the sheared off end to be removed, or the shearing may penetrate only through the weld zone, providing a notch, but leaving the flanges in place.

Abstract: A hydroacoustic transducer for generating and applying acoustic energy to a load coupling structure has a hydroacoustic amplifier with a driver stage and a power stage. The power stage includes a valve, which obtains high power conversion efficiency by operating to switch the flow of pressurized hydraulic liquid on and off thereby providing a switching amplifier which presents a pressure source of acoustic energy. This source is connected to a load coupling structure by way of an acoustic transformer and an inertive element in series with the source. The inertive element is provided by a liquid-filled bore and is terminated at its input end by the larger area of a stepped piston which provides the acoustic transformer. The smaller area of the stepped piston is in hydraulic communication with the power stage of the hydroacoustic amplifier.

Abstract: In order to stress relieve exposed portions of plastic welds, and thereby reduce susceptability of such welds to solvent-induced crazing and cracking, the welded parts are formed with flanges extending outwardly therefrom. These flanges are at least partially joined during welding, their adjoining surfaces providing at least a portion of the welded joint. After welding, the flanges are compressed in a direction transverse to their adjoining welded surfaces, the compression being of sufficient magnitude to exceed the yield strength of the flanges, thereby relieving stresses in the exposed portion of the welds. The flanges may be sheared, as by a blade which provides both transverse compressive forces and compressive forces in the direction of the adjoining welded surfaces. The flanges may be sheared through, so as to enable the sheared off end to be removed, or the shearing may penetrate only through the weld zone, providing a notch, but leaving the flanges in place.

Abstract: A seismic source drives one or more jets of high velocity water into an underwater environment and then terminates the jets by means of a valve member, the motion of which is controlled to obtain precisely timed high energy seismic pulses to provide reflected signals from which high resolution seismograms may be obtained when the signals are processed.

Abstract: To relieve stresses in a plastic weld which may weaken the weld and increase its susceptibility to solvent-induced crazing or cracking, forces are applied to the weld zone (the interface between welded parts) after it has cooled to solid condition, but preferably when it is at a higher temperature than the regions of the parts adjacent thereto, which forces are higher than the yield strength of the material at the weld zone and lower than the yield strength of the material in the regions of the parts adjacent to the weld zone. The forces thereby cause yielding or plastic deformation which effectively relieves certain thermally induced stresses in the weld. Tensile stresses in the weld are thereby relieved, to reduce susceptibility of the weld to solvent-induced crazing or cracking.

Abstract: A seismic source operable in deep bore holes, and especially suitable for acoustic well logging and geophysical exploration, produces a controlled-spectrum seismic impulse. The source has a hammer which is hydraulically cocked through a hydraulic transformer into a hydraulic spring. Upon command, the hammer can be released, converting stored energy in the spring to kinetic energy of hammer motion. The hammer impacts on a liquid impulse shaping spring which couples impulse energy of controlled spectral width to the formation surrounding the hole by means of a balanced piston assembly which can be prebiased against the side walls of the hole.

Abstract: A fast acting hydraulically actuated ram (10) especially suitable for use in the punch head of a press uses a first ram area (28) to advance the ram until the load thereon increases, which occurs when punching is about to take place. Then a pressure actuated valve (22), which is responsive to the increase in hydraulic pressure acting upon the first ram area, places pressure on a large area (36) of the ram for a time sufficient to enable penetration of the work. An electrohydraulically controlled valve (20, 98) responsive to the ram position, switches hydraulic pressure which is applied to the first ram area so as to operate the ram under electrical control to provide the desired cycle time and frequency.