Abstract: A transducer (700) of great sensitivity is disclosed which incorporates a magnetohydrodynamic (MHD) cell (738) exposed to the flow of a electrically conductive fluid (712) within a channel (704). Flexible diaphragms (722) form the ends of the channel (704) and deflect with the fluid motion. The deflection is sensed by strain gauges (724) and the signals from the MHD cell and strain gauges are processed. In addition, an MHD power generator is contemplated which generates power from a moving electrically conductive fluid, such as sea water in geophysical motion. A strong magnetic field is established normal the direction of fluid flow. Electrodes are positioned normal to both the magnetic field and fluid flow to complete a circuit to transfer the power generated by the movement of the electrically conductive fluid through the magnetic field.

Abstract: A seismographic sensor is constructed from a D'Arsonval movement. The elements of the movement include a coil suspended in the field of a permanent magnet and a pointer attached to the coil. A weight is attached to the pointer and acts as an inertia element. Leveling screws are provided to control the period of the weighted pointer and to control the resting position of the pointer. When the base of the meter vibrates during an earthquake, the weighted pointer does not follow the vibration because of its inertia, resulting in a relative rotation of the meter coil and the magnet field, thereby inducing a voltage in the coil. This voltage is proportional to one component of horizontal velocity of the earth's motion. Means are provided to process and record the magnitude of this voltage.

Abstract: Inertially insensitive optical fibre hydrophones are described, utilizing materials and configurations to obtain acceleration balanced designs suitable for underwater applications where acceleration is a problem. Balancing and/or insensitivity is obtained both in longitudinal and axially perpendicular directions. Acoustic sensitivity of a coil formed by the fibre is maintained by the properties of materials used to provide a rigid former, encapsulant material and secondary material which form the hydrophone.

Abstract: An acoustic filter is provided for attenuating or suppressing the negative pressure half-waves of an elastic wave, comprising an enclosure containing a liquid whose saturating vapor tension is close to the atmospheric pressure. A pump causes the liquid to flow and a regulator fixes its temperature.

Abstract: Apparatus is disclosed for detecting partially submerged wires and determng the location of the above water portion thereof by injecting into the submerged portion a radio frequency electrical signal, and utilizing radio direction finders to obtain a fix on the resulting radiating above water portion. An insulation cutting probe is used, and a radio frequency injection signal generator is described that minimizes power loss to the water medium.

Abstract: An elastic pulse generator including a piezo-electric or magnetrostrictive transducer which is focussing or associated with a focussing device, having a plurality of elementary emitting surfaces generating elastic signals. These signals are superimposed, after propagation over a certain distance, in a focal region. Several groups of elementary emitting surfaces are periodically exciting at a predetermined rate with respective separate electric signals. The emitting surfaces belong to transducer elements electrically isolated from each other and having different transfer functions. Delay lines are provided for phase shifting the elastic signals emitted by the transducer elements.

Abstract: A thermocouple consists of a first thin layer of metal disposed on a mylar sheet. The metal layer is then covered with a varnish by employing a printing process which prints spaced apart apertures on the metal layer indicative of a hot junction and a reference junction terminal. Another top metal layer is deposited upon the varnish layer in a line grating pattern to cover one hole in each pair to thus form a hot junction by connecting the top metal layer to the first layer via the hole. The other aperture forms one terminal of the reference junction. The metal layers are extremely thin as deposited by a vapor evaporation process and hence the thermocouple exhibits a rapid response to temperature change. The method of fabrication of the devices enables one to provide mass produced units at extremely low cost.

Abstract: A long-life, low-maintenance air gun/hydro gun includes a one-piece, integral shuttle having an unusually long hollow shank with a firing piston whose configuration is the mirror image of the operating piston, except for the slightly smaller diameter "D" of the firing piston. The shank length L is at least 2.5 times D, and the whole shuttle is guided by this shank sliding within a shaft seal and bearing assembly. By virtue of this guidance, the perimeters of the operating and firing pistons are always kept slightly spaced from their respective associated cylinder walls for eliminating contact of these pistons with their cylinder walls for advantageously dramatically increasing the total number of operating firing cycles which can be accumulated in use before the need for replacing any worn parts, except for the operating and firing seals which are inexpensive. Thus, this air/hydro gun offers a low-maintenance feature.

Abstract: This is an apparatus for measuring the intensity of a seismic shock applied to the apparatus. The apparatus includes an enclosure in which is a system of weights movable in response to an applied mechanical shock, and connected to a movable transmission member. The transmission member contacts a first spiral cam rotatably mounted on a balanced rockable lever. The cam turns the lever angularly when the transmission member is moved by the weights. A spring connected to the lever tends to inhibit it from turning out of its balanced position when the transmission member moves. A second spiral cam is also rotatably mounted on the lever. A fixed stop member contacts the second cam to prevent the lever from turning back to its original balanced position when the lever is turned out of this position in response to an applied mechanical shock. An index needle connected to the lever indicates on a scale the amount that the lever has turned.

Abstract: An acoustic energy absorbing baffle comprising a fluid containment means having an acoustic window means, a viscous fluid contained within said fluid containment, a porous material comprising strands of wire and being immersed within said viscous fluid means, a compliant mass means and means for holding said compliant mass means in close proximity of said porous material means such that the motion of said compliant mass means is imparted to said porous material. Incident acoustical energy is transmitted through the acoustic window and translated into energy absorbing motion of the porous material by acoustical excitation of the compliant mass means.

Abstract: A piezoelectric transducer in which a casing is mounted in a sealing manner on a base member for supporting two rod-shaped terminals, a piezoelectric element is bonded to the inner surface of said casing, and electrodes on the front and back surfaces of said piezoelectric element are electrically connected to said terminals. The transducer is supported at the position of a node of the free oscillation mode or the forced oscillation mode. The interior of the casing in the transducer is filled with nitrogen gas.

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: A thermocouple element (10) for use in high-pressure, high temperature fluid applications having a cylindrical body portion (12) formed from a first metal and a cap (14) formed from a dissimilar metal. The cap is fused to the body such that the junction (18) forms an axial thermocouple junction. A plurality of grooves (13, 20) is formed in the cap and body to reduce the mass of material adjacent the junction for rapid conduction heat transfer from the fluid being monitored.

Abstract: A reinforcing device to achieve stable fastening points for the inner portion (2) of seismic cables, especially cables that are towed laterally displaced in parallel in relation to the towing vessel and provided with at least two layers of armoring (5,6) intended for absorbing stretch loads on said cable, comprises a fastening means on at least one of the end areas of the inner portion (2), and gripping surfaces for external equipment and shaped with at least two securing chambers (3,4). For assembling the outermost layers of armoring (5,6) of said cable are separated and inserted into one chamber each (3, 4), wherein they are secured to form an integrated connection with said casing (2).

Abstract: The method uses a tubular shaped and electrically conductive well casing that extends to a geological formation in an oil or gas well. The casing is used for both flowing fluid between the formation and the casing at the top of the well and for communicating data representative of a parameter in the well to the casing at the top of the wall. A tool carrying a switch and an electrical contact is inserted down the inside of the casing. The contact on the tool is connected to the inside of the casing. The flow of the fluid between the geological formation and the casing at the top of the well through the side of the casing above the tool is controlled. A parameter in the well adjacent the formation is sensed. The switch in the tool is operated for sequentially connecting together and disconnecting the contact to a return electrical path to the top of the well for causing changes in the conductance between the casing and the return path representative of data about the parameter.

Abstract: A method and apparatus using a multiple transducer acoustic logging tool to detect fractures surrounding a borehole, particularly fractures that do not intersect the borehole wall. The transducers are actuated to produce broad band width pulses and signal enhancement techniques are used to determine fracture width, orientation and distance from the borehole wall.

Abstract: An interferometer inhibits a received low frequency acoustic signal that is elow the pass band of interest from appearing in the output. The interferometer has a conventional optical hydrophone in the signal leg to sense both the high and low frequencies of an acoustic signal. The reference leg has means for accepting a low frequency acoustic signal to modulate the coherent light path length while inhibiting the desired high frequency signal. On recombining the signals from both the signal and reference legs the low frequency signal appearing in both legs is canceled and only the high frequency signal appearing in the signal leg reaches the output. In an alternate embodiment the reference leg mandrel is placed internal to the sensor mandrel and provides a low frequency compensation chamber.

Abstract: A method and apparatus are provided for inhibiting unauthorized copying, unauthorized usage and automated cracking of proprietary software used in computer systems. The computer systems execute protected programs, which are protected by encapsulation and/or encryption. To provide security against unauthorized copying of software, means are provided that detect and inhibit automated cracking of protected programs. These means will destroy or make inaccessible information in the CPU during conditions when automated cracking could occur. These means will also store interrupt contexts in secret to prevent implementation of automated cracking. Additional features may be provided to allow operation as a general purpose computer system, where protected programs are distributed using public key cryptography and a means is provided to convert from this distribution form to the protected execution form.

Abstract: The invention provides an improved method and apparatus (10) for measuring the velocity and amplitude of sound waves (150) from acoustic pulses (145) generated near the mudline (130) of the seafloor (120). The apparatus (10) includes a seismic source (30) for generating the acoustic pulses, one or a plurality of vertically spaced sensors (50) located vertically below the seismic source (30) for sensing when the sound waves (150) impact the sensors (50), a hydrophone sensor (200) located on the vessel (60) for measuring the distance to the seismic source (30) a crane and winch for pulling the embedded sensors (50) upwardly and out from the sediments, and means (100) for firing the seismic source when said sensors (50) are being pulled upwardly, for taking amplitude and velocity measurements from each sensor, and for determining the distance the sensors have been pulled upwardly for each acoustical pulse operation.

Abstract: A seismic signal is created, processed and recorded and then analyzed to determine the nature of subterranean formations.