Abstract: An ultrasonic transducer comprises a support body, a piezoelectric layer of a material with a relatively high dielectric constant and high acoustic impedance, a first impedance matching layer and a second impedance matching layer (10). The first matching layer consists of silicon.

Abstract: A vibrator seismic source has a sweep generator for providing a pilot signal and sensors for generating a feedback signal representative of the force imparted to the ground by the vibrator pad. Circuitry is incorporated for separating the fundamental signal from the feedback signal and for separating the distortion from the feedback signal. Means are provided for generating a control signal for controlling the action of the vibrator means. Included are means for reducing the amplitude of the pilot signal a designated amount, determined by the distortion, and means for algebraically summing the reduced amplitude pilot signal and the fundamental signal to provide an error signal. The error signal is input to a loop filter to perform real time correction of the control signal. The reduced amplitude pilot signal is input to means for adjusting the control signal for trends in the distortion.

Abstract: A physical condition in a well bore is sampled and information taken from the sample is recorded by a method of conserving electrical energy in performing such sampling and recording. The method sequentially energizes and de-energizes a plurality of different electrical circuits within the downhole apparatus with which the physical condition is detected and in which the information is recorded. The method determines when the next sample is to be taken and, depending upon how much time remains until the next sample, de-energizes the apparatus to conserve energy.

Abstract: The present invention relates to an apparatus and method for calipering a borehole using acoustic measurements within the borehole. These acoustic measurements are useful for measuring the reflectivity of the side walls of a borehole and for calipering a borehole in a wireline or measurement while drilling configuration. The apparatus comprises at least one acoustic transceiver disposed on a calipering tool, together with a second acoustic receiver disposed longitudinally a selected distance from the first receiver. Further, a second acoustic transceiver is disposed on the caliper tool azimuthally from the first transceiver. Measurement of the travel times of acoustic pulses reflected from the borehole walls by the transceivers and receivers of this device, together with other known data, permits an accurate caliper of the borehole to be produced.

Abstract: Apparatus for measuring the force actually exerted by the base plate of a seismic vibrator on the earth surface is provided. This apparatus consists of a plurality of individual sensor elements, which are arranged on the side of the base plate which is directed towards the earth surface. The sensor elements couple the energy from the base plate to the earth surface.

Abstract: The method for controlling the rate at which a downhole logging tool samples and records a detected condition obtains three samples of the condition at three consecutive sample times and computes a prediction value for the n-th sample from the first three samples. The method compares the actual n-th sample with the predicted value and records the (n- 1)-th sample if the variance between the predicted and actual values is outside a predetermined threshold or difference. The sample rate is changed if the actual values of the samples remain within the predicted value's preselected range for more than a preselected number of samples. The sample rate interval is also increased if the battery life or memory capacity decrease below predetermined thresholds. The sample rate interval is decreased to its shortest interval if a pressure change above a predetermined threshold is detected.

Abstract: A full waveform seismic source is described which is adapted to propel a heavy mass powerfully downward against the surface of an earth-contacting target plate. Means are provided for rotating the barrel of the actuator about two mutually perpendicular horizontal axes so that energy can be delivered to the earth along a plurality of preselected slant paths. In this way, any desired combination of compressional and shear waves, both SH and SV type, may be generated at a point on the earth's surface. The target is contoured so that any slant path followed by the accelerating mass always impacts the target normal to its surface.

Abstract: A vibratory seismic surface source includes a single vibrating mass, supported above and independently of an earth-contacting base plate. Means are provided for varying the inclination and azimuth of the vibrator axis. After the vibrator is oriented in any desired direction, it is then lowered along its vibratory axis so that it bears directly against the hemispherically concave upper surface of the base plate. When the vibrator is actuated in this position of contact, any desired combination of compressional and shear waves, both SH and SV type, may be generated and recorded simultaneously at a point on the earth's surface remote from the source.

Abstract: A technique for a vibration isolation module (VIM) used for towed arrays is disclosed. The VIM has a stretchable cable on which is mounted one or more rigid spacers which make contact with an outer hose formed of a flexible material having a selected vibration attenuation characteristic. The spacer transmits energy between the parts of the VIM which contact the spacer for attenuation purposes. The spacer is "soft mounted" on the stretchable cable so that it may be moved by a limited amount along the cable in response to forces of a specified minimum magnitude. This ability to move allows adjustment of the internal parts of the VIM during use to avoid concentrating stress at any one particular contacting area. Disclosed is an embodiment where two sleeves are used to abut the spacer at opposing ends thereof.

Abstract: An electromagnetically driven vibratile piston underwater transducer element generates acoustic intensity levels in the order of 50 peak Watts per square inch of radiating surface in the low audible frequency region in the vicinity of 1 kHz. The design achieves an efficiency greater than 50% and a very low Q of less than 2. The air gap is designed to seat mechanically if the unit is operated accidentally at high-power levels while acoustically unloaded thereby protecting the spring assembly from unsafe amplitudes of vibration. The mechanical protective design also serves to protect the transducer vibrating structure from failure if the transducer is exposed to the proximity of an underwater explosive shock wave. The transducer construction results in a minimum overall length so that when the transducer element is mounted in a planar array attached to the hull of a vessel the projection of the radiating surface of the array from the surface of the hull is minimized.

Abstract: A vibratory seismic surface source includes a hydraulic vibrator the energy of which is coupled into the earth through a ground contacting base plate. The vibrator is supported above and independently of the base plate so that it may be pivoted about a first rotational axis within a truck-mounted gimbal-type frame which itself is tiltable about a second horizontal rotational axis perpendicular to the first. After the vibratory axis is oriented in the desired direction the vibrator is lowered so as to contact a suitably contoured upper surface of the base plate. Inclination of the vibrator is accomplished by "push-pull" operation of pairs of oppositely-directed hydraulic cylinders.

Abstract: A system and method for sensing the status of a plurality of valves by detecting the total current flowing through a network of constant current devices connected in series with a plurality of limit switches responsive to the open and closed positions of the valves. The system uses a binary constant current encoding network to provide a total current that is a unique binary weighted indication of which switches are closed. The system includes a current measurement circuit that converts the current to a voltage, filters out noise and amplifies the voltage for input to an analog to digital converter. The output of the analog to digital converter is then decoded by a logic hardware or by a computer to derive a digital output indicative of the position of the switches. A bipolar voltage source energizes the constant current encoding network and interacts with the current measurement and decoding circuits to ensure a sufficient voltage level for constant current operation.

Abstract: There is disclosed a polymeric piezoelectric ultrasonic probe using a polymeric piezoelectric member which comprises a polymeric piezoelectric member; a common electrode formed on one surface of the polymeric piezoelectric member; and electrodes for driving provided as opposed to the common electrode with the polymeric piezoelectric member being interposed therebetween, the electrodes for driving being formed on a polymeric thin film.The polymeric piezoelectric ultrasonic probe of the present invention has advantages that not only breaking or short circuit of electrodes shaped in rectangular strips can be prevented, but also it becomes possible to connect lead wires with good reliability. Besides, not only cumbersomeness is registration of electrodes shaped in rectangular strips during lamination of polymeric piezoelectric members can be cancelled, but also acoustic-electrical coupling or cross-talk can be reduced.

Abstract: A time division multiplexing, fiber optic data gathering system, including two or more sensors formed on an optical fiber, and a phase sensitive detector. Each sensor includes two reflectors separated by a section of the fiber having length L. Each reflector may be activated so that when an interrogating light signal propagates in a first direction past the activated reflector, a portion of the interrogating light signal will be reflected back into a direction opposite the first direction. Each reflector may also be deactivated so that the interrogating signal may propagate unhindered past the deactivated reflector. Variations in the optical path length between the reflectors of a sensor, due to changes in an external parameter of interest, will cause phase modulations that are extracted in the phase sensitive detector by homodyne or heterodyne techniques.

Abstract: A measuring and telemetry system is disclosed adapted to measure the ambient pressure and temperature in a downhole environment, and to telemeter signals representative of such measurements to the wellhead for demodulation and display. Only two wires are used in the system between the wellhead and the measuring location downhole. The two wires are used for both the power applied downhole and measurement signals transmitted uphole. A current balance circuit is provided for a downhole iron core transformer through which the DC power is provided through one winding. The current balance circuit senses a signal representative of the DC current flowing through the one winding and applies an equal in magnitude but opposite in direction current through the other winding of the transformer to prevent magnetic saturation of the transformer.

Abstract: Each IDT (inter-digital transducer) of a SAW (surface acoustic wave) device has a linearly tapered back edge formed by reflection-suppressing fingers of successively decreasing length spaced apart with a pitch of lambda/4 behind the active region of the IDT, where lambda is the wavelength of a SAW to be propagated, whereby SAW reflections at the back edge of the IDT are substantially eliminated. A thin resistive doped silicon film between the back edge of each IDT and the adjacent edge of the substrate absorbs waves propagated via this back edge. The film underlies the IDTs to provide improved adhesion to the substrate.

Abstract: Ribbon termination member has thread therein for connection to a coupling between sections of the towed array. First and second pins have cylindrically curved front surfaces upon which legs of the flexible ribbon tension member are engaged. The curved surfaces permit transfer of tension loads between the flexible tension ribbon and the pins. The second pin has an extended bearing surface 92 for preventing damage to the ribbon when loads are out-of-line.

Abstract: A sound transmitter for generation of transient acoustic pulses, comprising a spatially curved focussing emitter surface which is represented by the area of a single active or passive emitter or by the areas of several emitters matched in respect of their period of operation and amplitude. The pulses occurring in the region of the focus are generated by a substantially unipolar and chronologically limited pressure and/or velocity evolution at the emitter surface.

Abstract: A composite layered assembly of piezoelectric polymer layers and printed wiring layers are configured so that plated-through holes make electrical connection from the outputs of a plurality of polymer hydrophones formed on one or more polymer layers to a plurality of output conductors on a single plane after each hydrophone output is amplified in its associated amplifier.

Abstract: An ultrasonic transducer comprises a cylindrical housing embedded within a rear bumper of a vehicle and opening backward, a reflecting plate having a parabolic reflecting surface provided within the cylindrical housing along a closed end thereof and facing an open end thereof, and an ultrasonic vibrator provided in an upper wall of the housing at the focus of the reflecting plate for emitting and receiving ultrasonic waves. The ultrasonic transducer transmits ultrasonic waves behind the vehicle and receives ultrasonic waves reflected from an obstacle. The ultrasonic transducer further comprises a projecting member provided on the inner wall of the housing along the open end thereof for dispersing and cancelling the ultrasonic waves entering the housing at angles with respect to the axis of the housing. The projecting member has a smoothly curving cross section having a radius of substantially one fourth to five times the wavelength of the ultrasonic waves emitted by the ultrasonic vibrator.