Abstract: A method and apparatus for determining source location for acoustic or other waveform energy in a conducting medium. The method includes simultaneously detecting and transducing the source energy at a plurality of points in the medium into a composite signal representative of the source energy, as sensed at each point. Dispersional modes of propagation of the energy, if more than one, are isolated from each other, preferably by Fourier transform spatially and temporally. Generalized cross correlation is performed on selected isolated modes, resulting in identification of a value from which source location can be located. The apparatus can include an array of spaced apart transducers which are configured to be minimally interfering with source energy propagation through the medium. An multi-channel data acquisition device, including A/D converters for each transducer, captures and digitizes the output of each transducer simultaneously.

Abstract: A method of detecting damage in a ferromagnetic workpiece such as a boiler tube positions a pair of EMAT coils adjacent to the workpiece at a non-zero angle with respect to one another. A spike pulse is applied to one of the EMAT coils for generating a horizontally polarized shear wave in the workpiece which is capable of being reflected by a flaw, and the amplitude of a reflected wave from any flaw is received at the other EMAT coil and analyzed and compared to a predetermined percent of an amplitude of a calibration standard flaw to establish the presence of the flaw.

Abstract: A transducer for a vibratory viscometer includes a hollow cylindrical sheath and a hollow cylindrical shaft disposed within the cylindrical sheath. The shaft has a first end portion and a second end portion connected to a distal end portion of the sheath. The viscometer includes a sensor tip connected to the distal end portion of the sheath. The sensor tip has an inner surface defining a hollow region and a support tube disposed within the hollow region configured to hold a temperature sensor. The viscometer further includes a crossbar coupled to the first end portion of the shaft.

Abstract: In order to determine the nature of fluid passing through a pipe, for example whether material being pumped through a pipe is sludge or liquid phase, high frequency ultrasonic pulses from a generator are caused to propagate around a peripheral wall of the pipe to produce ringing in the pipe, and the characteristics of the ringing are measured and compared in a controller with stored data to determine the nature of the fluid content of the pipe. A sludge pump may be controlled according to whether the data obtained shows that the material passing through the pipe is sludge or liquid tunnelling through the sludge.

Abstract: A leak detection device securable in detection proximity to a fluid vessel. The leak detection device includes a sensor element and a monitoring assembly. The sensor element has a monitorable characteristic, and the monitorable characteristic changes upon contact, immerson or in exposure to the fluid contained in the vessel. The monotoring assembly is responsive to the monitorable characteristic and produces an changing electrical output in response to change in the monitorable characteristic. The vessel and leak detection device may form an assembly including a shroud or cover over the detection device and a leak-susceptible portion of the vessel, to provide a microenvironment in which the detection device is operated.

Abstract: A hydrogen sensor including a piezoelectric device with a hydrogen-interactive metal film that reversibly interacts with hydrogen to provide a correspondingly altered frequency response characteristic, relative to the frequency response in the absence of hydrogen. The piezoelectric device may be for example a quartz microbalance or a surface acoustic wave device, having a thin film (e.g., 10-100,000 Angstroms thickness) coating thereon of a hydrogen-interactive metal such as palladium, platinum, nickel or the like.

Abstract: Device for testing ferromagnetic materials, such as pipelines and the like, for faults, cracks, corrosion, etc. An one electromagnetic ultrasonic transducer includes at least one high frequency current coil and an arraay of permanent magnets which create a magnetic field for exciting and/or detecting ultrasonic waves in the wall of the ferromagnetic material. The ultrasonic transducer is located between the pole pieces of an additional magnet arrangement that produces a magnetic prefield in the material wall.

Abstract: This invention relates to a carrier for a pipe and line locator which facilitates the use and operation of the locator in that the carrier includes a grounding rod for making it easy to connect a grounding output of the transmitter to ground, thereby enhancing the efficiency of using the locator. The grounding rod on the locator is associated with the handle that is used to lift and transport the carrier and to cause penetration of the ground with the grounding rod upon placing the carrier with the locator on the ground.

Abstract: A method is provided for testing prestressed concrete pipe. In the method, elastic waves are serially induced at at least three different inducing locations along the surface of the conduit. The shear wave component of each induced elastic wave is detected by at least one, and preferably two, acoustic sensors disposed at fixed sensing sites along the conduit. The relationship between at least one parameter of each induced shear wave and the distance between each inducing location and the acoustic sensor(s), are correlated and compared with standard correlations to identify structural discontinuities in the conduit. In a typical example of the method, elastic waves are induced using a mechanical hammer at multiple inducing sites around a multiplicity of annuli along the length of the conduit. Each annulus is separated from adjoining annuli by 2-4 feet.

Abstract: A flaw detection system for a prestressed concrete cylinder pipe uses hydrophones inserted into valves in the pipe while the pipe is in use. The hydrophones listen for sounds that are consistent with the breaking of the pre-tensioned reinforcements and the sliding and re-anchoring of broken ends. Detecting the sound at two or more locations and establishing precise time differentiation allows the precise calculation of the location of the defect. Global positioning system (GPS) satellite receivers provide precise timing of reception of the targeted sound events in milliseconds. The location of each of the hydrophones is established using GPS. Each hydrophone is connected to a box, which includes a pre-amplifier, a signal processor, a memory, an output and a GPS receiver. The hydrophone, or box, or both, are tunes to recognize a significant sound that emanates from a breaking, moving or re-anchoring reinforcement. The precise time of arrival of that sound is recorded in the boxes using the GPS time signals.

Abstract: An imaging system is described which can be used to either passively search for sources of ultrasonics or as an active phase imaging system, which can image fires, gas leaks, or air temperature gradients. This system uses an array of ultrasonic receivers coupled to an ultrasound collector or lens to provide an electronic image of the ultrasound intensity in a selected angular region of space. A system is described which includes a video camera to provide a visual reference to a region being examined for ultrasonic signals.

Abstract: The invention relates to detecting leaks in a pipeline using enhanced methods of data sensing, digitally encoded transmission, and cross-correlation. A plurality of acoustic sensors are applied to the pipeline to sense a combination of signals from the leak and much greater quantities of noise. The sensed data is digitized at the sensor, encoded and digitally transmitted to a computerized base station. The encoded data from a plurality of sensors received at the base station is decoded, digitally filtered and cross-correlated. Enhanced methods of cross-correlation are performed to estimate the likely presence of a leak and the location and size of any leaks present. Participation in the leak detection procedure by an expert not present at the pipeline is facilitated by communication of data between the base station and a distant supervisory station.

Abstract: An ultrasonic leak detector with a wide dynamic bandwidth and repeatable fixed attenuation reference points includes a transducer which receives ultrasonic energy and converts it into an electrical output signal related in intensity and frequency to the received ultrasonic energy. A high gain charge preamplifier is connected to the transducer and generates an amplified version of the transducer's electrical output signal. The amplified signal is then passed through a multi-level logarithmic attenuator having at least one fixed attenuation reference point to create an attenuated version of the detected and amplified ultrasonic signal. The output of the logarithmic attenuator is connected to a frequency shift circuit which converts the ultrasonic frequency signal into an audio frequency signal related in magnitude and frequency to the attenuated signal.

Abstract: For performing a noise measurement in a pipe (16) traversed by a fluid such as air, in the pipe is placed a measuring device comprising a pipe section (10) having the same cross-section and in which is formed an elongated slot (18). The slot (18) is covered with a resistive material (24) and capped by a cavity (26). The ends of the cavity form an acute angle of at the most approximately 7.degree. relative to the axis of the pipe section (10). One or more microphones (34) are installed on the cavity (26), facing the slot (18), so that its diaphragm (36) is flush with the inner face of the cavity.

Abstract: A leak noise correlator apparatus comprises first and second data logging units having acoustic transducers connected to them for application to a fluid-carrying pipe either side of a suspected leak. One data logging unit is arranged to communicate an initialising signal to the other unit to synchronise the substantially simultaneous acquisition of signals by the two units. This initialising signal is communicated by an infra-red link when the two units are brought together prior to installation at their respective sites on the pipe. Subsequent cross-correlation of the acquired data records determines the location of the leak.

Abstract: An apparatus and method for directing ultrasonic and magnetostrictively generated mechanical waves from an exterior point to an interior point within a small diameter tube, pipe, or cylindrical structure. The present invention incorporates an external mechanism for generating waves in a cylindrical waveguide tube gun of a size small enough for insertion into the target tube and configured so as to maintain mechanical contact with an inside diameter of the target tube. Standard ultrasonic wave generating devices or magnetostrictive/mechanical wave generating coils are positioned on the waveguide external to the target tube and generate appropriate mechanical waves through the waveguide to a point interior to the target tube. A mechanical interface between the waveguide and the inside diameter surface of the tube is positioned and provided at a point within the target tube to transfer both the interrogating waves and the received return signal waves between the target tube and the waveguide.

Abstract: Apparatus and method for comparing corresponding acoustic resonances in liquids. The present invention permits the measurement of certain characteristics of liquids which affect the speed of sound therein. For example, a direct correlation between the octane rating of gasoline and the speed of sound in a gasoline sample has been experimentally observed. Therefore, changes in the speed of sound therein can be utilized as a sensitive parameter for determining changes in composition of a liquid sample. The present apparatus establishes interference patterns inside of a liquid without requiring the use of very thin, rigorously parallel ceramic discs, but rather uses readily available piezoelectric transducers attached to the outside surface of the usual container for the liquid and located on the same side thereof in the vicinity of one another. That is, various receptacle geometries may be employed, and the driving and receiving transducers may be located on the same side of the receptacle.

Abstract: An apparatus and method for pigging, flooding, and pressure testing pipelines utilizing a sliding sleeve valve connected at the end of a pig receiver which automatically opens upon fluid pressure in the pipeline reaching a predetermined limit allowing fluid trapped in the pipeline to escape, and is then automatically closed when the pig enters the pig receiver to allow pressure testing of the pipeline. The present apparatus and method eliminates the need and expense of a crew and/or a separate support vessel with divers or an ROV system at the downstream end of a pipeline during pigging, flooding, and pressure testing of the pipeline.

Abstract: A method for thermal volume modeling of the pipe fluid volume change by taking temperature change measurements of pipe fluid taken at a single location, and comparing it to the changes in the fluid volume inside a tank hydraulically connected to a said pipe; a method of determining a fluid leak by comparing a calculated fluid volume inside a tank(s) and the actually measured tank fluid volume, where calculations are based on the method.

Abstract: A fluid sensor includes a base body 2 having a vibrating portion 7, a piezoelectric element 3 which is fixed onto one surface of the vibrating portion 7 and has a piezoelectric film 4 and at least a pair of electrodes 5a, 5b which are disposed in contact with the piezoelectric film 4, an electrode terminal 6 which is disposed on the surface of the base body 2 and electrically connected to the pair of electrodes 5a, 5b, a coating material 8 which is disposed on the surface of the base body 2 in the periphery of the electrode terminal 6; pressure plates 14a, 14b, and a sealing member 12 which is held between the base body 2 and the pressure plates 14a, 14b and formed so as to surround the electrode terminal 6, wherein the electrode terminal 6 is held gas-tightly and/or liquid-tightly with respect to a fluid to be measured by holding the sealing member 12 between the coating material 8 and the pressure plates 14a, 14b.

Abstract: A sensor structure for use with container inspection systems utilizes a continuous-wave (CW) microwave radar to measure the curvature or the vibration characteristics of a container wall through a thick corrugated cardboard case top or on a single item container processing line. A radar antenna directs RF energy toward cans moving along a conveyor. The antenna emits a beam which, over time, illuminates a narrow region along a line from one outer edge of the can to the opposing outer edge, as the can passes the antenna. During this time, a continuous measurement of the relative change in distance from the antenna to the top of the can is generated and sampled for acquisition by a computer, and an estimate of the profile is made from changes in the distance measurement. The profile is used as a measure of the internal pressure of the can or as an indication of the presence of manufacturing defects.

Abstract: An ultrasonic detector of the present invention includes an ultrasonic transducer for detecting ultrasonic energy and generating an electrical signal having an amplitude corresponding to the detected level of the received ultrasonic energy, and a light source supported in proximity to the ultrasonic transducer for illuminating an area from which the ultrasonic transducer may detect ultrasonic energy. Preferably, the light source is a directional light source positioned such that an optical axis of a light beam emitted from the light source intersects a directional axis of the ultrasonic transducer at a predetermined distance from the ultrasonic transducer. The ultrasonic detector of the present invention also preferably includes an indicator light coupled to the ultrasonic transducer for receiving the electrical signal output from the transducer and for indicating the relative amplitude of ultrasonic energy received by the transducer.

Abstract: An acoustic pressure gradient sensor able to detect a sound signal. The sensor includes a mechanical-acoustic device formed of a sphere that has omnidirectional sensitivity to the pressure gradient, an electromechanical device that accommodates the mechanical-acoustic device and that transforms the stresses into electrical impulses, and an electronic device to process the electrical impulses. The electromechanical device is formed of two printed circuits that incorporate low noise amplifiers. The printed circuits are separated by beams. The arrangement of the beams marks out a triangular structure. Each of the beams carries a gauge to measure the stresses.

Abstract: A photo-acoustic leak detection system for detecting a gas leaking from a component (30), includes at least one laser beam (20), incident on the component (30) and having a wavelength which is absorbed by the gas, the gas emitting a photo-acoustic signal (36) when the gas absorbs light from the beam (20), the beam (20) being pulsed at a pulse frequency, the pulse frequency being related to a detection frequency of the photo-acoustic signal and being a frequency at which the magnitude of background acoustic noise at the detection frequency is at a predetermined low level, at least one acoustic sensor (40), which receives the photo-acoustic signal (36) and provides a sensor signal on the line (42) indicative thereof to a filter (44) and a synchronous detector (18), which provide a filtered signal on a line (50) to a signal processor (52). The processor (52) provides an output signal on a line (54) indicative of the leak in the component.

Abstract: Changes in the internal diameter of a fluid handling pipes are measured by measuring the vibrational characteristics by a non-invasive, passive acoustic technique. Deviations from the normal vibrational characteristics are sensed and used to determine changes of increase or decrease in the pipe's internal diameter.

Abstract: An apparatus for monitoring the vacuum of a vacuum switch having at least one vacuum switch tube with a switch chamber and switch contacts is provided. The apparatus has a remotely interrogatable pressure measurement sensor in the form of a piezocrystal or surface acoustic (SAW) device arranged in the interior of the vacuum switch tube and a remote interrogation device placed external to the vacuum switch for monitoring the vacuum via the sensor.

Abstract: An apparatus and a method for quantifying the leak flow rate of a fluid from a fluid leak site in a piping system. An ultrasonic sound detector is used to accumulate sound level data for known leak sites in known piping system elements through which a known fluid flows at known temperatures and pressures. The accumulated data provide a database to permit the determination of fluid leakage rates in actual piping systems by comparing test data obtained for the actual piping system with the data contained in the database. In one embodiment of the invention, the database includes data corresponding to standard curves representing the relationship between accumulated sound level data and accumulated leak flow rate data. Based upon the cost of the fluid, the annual costs for fluid lost as a result of leakage can be determined, as well as the annual volume of fluid lost.

Abstract: A pipeline breakage sensing system includes a plurality of pressure sensors installed on pipelines to measure pressure of a fluid. Each of these pressure sensors presumes a breakage location in cooperation with other neighboring sensors on the basis of a pressure change of the fluid and transmits information relating to the presumed breakage location. The pipeline breakage sensing system further includes a pressure sensor for detecting the occurrence of a seismic earthquake event, in addition to a managing center for sensing a breakage location on the basis of information transmitted from respective pressure sensors and by calculating a time correlated comparison between the superimposed pressure readings from neighboring pressure sensors used to detect the occurrence of such a fluid pressure change.

Abstract: For reducing the coupling liquid carried along during the performance of a test run of a device for testing gas carrying pipelines, the invention provides an ultrasonic gas carrying pipeline testing method, in which an overpressure is produced in a space containing a sensor carrier with ultrasonic sensors and a coupling liquid defined by the pipeline wall and scraper sleeves. An ultrasonic gas carrying pipeline testing device with a sensor carrier and a scraper sleeve positioned upstream thereof and connected thereto is characterized in that a connecting line (24) provided with a pump (26) passes from an area upstream of the scraper sleeve (22) to an area downstream of said scraper sleeve (22).

Abstract: An apparatus and process for determining the existence and location of a leak in a vessel such as a container or an above ground or underground pipe, comprises a plurality of remote acoustic transmission sensor units distributed along the pipe and each containing equipment for analyzing acoustic signals from the pipe. The equipment includes a mechanism for identifying acoustic features of the acoustic signals which distinguish the acoustic signals of a leak from ambient acoustic signals. A control unit is connected to each of the remote units and includes additional equipment for further analyzing the signals to determine the proximity of the signal to a particular remote unit and, using the amplitude of the signal and the transmission characteristics of the pipe, determining the location of the leak.

Abstract: A portable computing device is used for acoustic testing of valve systems for valve leaks. Transducers are applied to appropriate locations in the valve system to obtain sound signals, which are fast Fourier transformed into valve signatures. Multiple signatures are displayed simultaneously and are compared automatically by the system to derive a recommended result and manually to make determinations of valve leaks by the differential signature method or the like. The signatures and the user's determinations are stored on a hard drive. Various panels are displayed to give the user step-by-step instructions for performing the test. The results can be reported to the client's office computers.

Abstract: Device and method for locating leaks in pipelines, overhearing even weak sounds, from leaking fluid especially in pipelines made of material with limited sound conductivity such as plastic. The device includes a first thin diaphragm with one side in contact with the fluid, whereby vibrations are transferred from the fluid to a second diaphragm joined to the opposite side of the first diaphragm. The second diaphragm is made of a preferably sound-sensitive piezoelectrical plastic foil, the diaphragms being able to co-vibrate with frequencies from one to a few thousand Hertz. The first diaphragm protects against the inner pressure in the liquid line and moderates any sympathetic vibration. The low-frequency A.C. that is generated by the vibration in the second diaphragm is amplified and transposed to a range of frequencies that is audible for the human ear.

Abstract: A buried pipe detection device based upon the principle of sensing of difences in the dielectric/conductive properties of the ground in the vicinity of the pipe is disclosed. Because the electrical properties of the ground directly over the buried pipe will differ from those of an area immediately adjacent to the pipe, the detection principle is embodied in a capacitor plate array that injects a low frequency sinusoidal signal into the ground and samples the injected signal from two spatially separated locations on the array. The capacitor plate array has two injector/sensor plates that form a capacitively coupled impedance bridge with the ground and a third plate to establish circuit ground. The injector/sensor plates sense changes in the ground path impedance directly beneath the plates as the array is moved along the ground. The outputs of the two sensor/injector plates are then combined differentially and are processed to provide a continuous analog or digital readout.

Abstract: A leakage-sound detecting apparatus is provided for efficiently detecting water leakage in a plastic pipe by increasing sensitivity to a low frequency sound component and efficiently reducing stray noise, as well as protecting a piezoelectric element. To this end a detection portion and a pedestal portion are connected through a mechanical resonant member formed of a soft material. A low frequency sound component is amplified by the resonant member, and high frequency components are substantially attenuated. In an alternative arrangement a detection portion and a mechanical resonant member mounted on a pedestal portion are connected through a buffer portion having a buffer member arranged therein. When a shock is applied to the bottom of the pedestal portion, due to the apparatus being dropped for example, the buffer member is compressed, and no overload is applied to a piezoelectric element.

Abstract: A new ultrasonic method for measuring wall thickness and detecting material flaws in natural-gas pipelines, risers, and similar structures. The method is inherently suitable for the task, because it relies on the use of the natural gas as the coupling fluid for transmitting the probing ultrasonic signals into and out of the pipe wall. Furthermore, the method facilitates the operation of the inspection from the inside of the pipe. An experimental apparatus used to demonstrate the technical feasibility of this approach and provide experimental and theoretical evidence that support the claims is described. Significantly, it is shown that by the use of a diplexer, the same transducer can be used to generate and detect the probing ultrasonic signals. The same configuration is used in commercial ultrasonic inspection of oil pipelines where oil is the coupling fluid; but until now this method could not be used in natural gas pipelines due to the low specific acoustic impedance of natural gas.

Abstract: An ultrasonic leak detector which discriminates against leak signals originating from outside a desired detection zone. Incoming ultrasonic waves are divided into mutually exclusive low and high frequency signals, which signals are then processed to form an intensity ratio. The intensity ratio is compared to a pre-selected ratio corresponding to an ultrasonic source at the boundary of the detection. Ultrasonic leak signals originating from outside the desired detection zone are ignored. The presence of a leak within the detection zone is indicated by audio and/or visual devices.

Abstract: The present invention determines the presence of a pig in a pipeline and the condition of the pig, as regards to the material the pig may be pushing, by passive acoustic detectors which determine the acoustic characteristics for the pipe and the pig. From these a computer is used to determine from changes in these characteristics the nature of the materials picked up by the pig or the condition of the pig and the pipe.

Abstract: A method for detecting degraded pipe used in water mains monitors detected sound waves and observes the characteristics of those waves. Water main pipes have coiled therearound highly tensioned steel wire which holds the concrete comprising the pipes in compression. When the steel wire is corroded by water seeping through mortar encapsulating the pipe, the steel wire eventually ruptures, thus relieving compression in the concrete adjacent the rupture. Sonic and ultrasonic sound waves traversing the concrete of pipes have different characteristics for pipe in good condition as compared to the characteristics of sound waves traversing pipe in poor condition due to decompression and/or other causes. The sound waves in pipe in poor condition travel slower with shear waves having less amplitude and reflections occurring at later times. In addition, the frequency domain characteristics of pipe in poor condition differ from the frequency domain characteristics of pipe in good condition.

Abstract: A method of locating a defect in a buried conduit by sensing vibrations generated at the defect, processing signals detected by sensors to generate a cross-correlation function, smoothing this function to obtain a peak, calculating a center velocity of acoustic energy propagation, and using the center velocity of acoustic energy propagation to calculate the location of the defect.

Abstract: A method for detecting corrosion fatigue cracks in membraned boiler tubes in a membrane tube panel employs at least one EMAT coil generating ultrasonic SH shear waves at a predetermined beam angle. The method of the present invention provides better signal-to-noise ratios than conventional ultrasonic techniques as well as not requiring any couplant.

Abstract: The invention is directed to a circumferential actuator for actively contling and generating pressure waves in a piping system having a fluid or a fluid flow therein. The circumferential actuator includes a casing, a plurality of actuator units mounted in the casing for generating controlled pressure waves, a plurality of amplifiers for electronically conditioning the force generated by each of the plurality of actuator units, a controller for providing the input signals to the plurality of actuator units for controlling the phase and amplitude of the generated pressure wave, and a pressure compensating system for providing a balancing force to each actuator unit. The casing is adapted for interconnection in fluid communication with the piping system for passing the piping system flow therethrough. The plurality of actuator units are arranged axi-symmetrically around the casing.

Abstract: A method and apparatus for detecting the presence of surface corrosion under insulation on a piping structure employs artificially generated, broadband acoustic sound waves to interrogate the piping structure. The sound waves are coupled into the piping structure and detected after they have propagated through and interacted with a portion of the piping structure. The amplitude of RMS voltage signals indicative of the detected sound waves is used to determine whether or not surface corrosion is present. Highly corroded pipes have been shown to yield relatively low RMS voltage signals whereas the lack of corrosion yields relatively high RMS voltage signals.

Abstract: A method of measuring a length of a conduit comprises the steps of: supplying air into a conduit to insert a filamentary body into the conduit by flow of the air; detecting arrival of a forward end of the filamentary body at an outlet of the conduit; and measuring the length of the conduit from the length of the filamentary body inserted into the conduit. An apparatus for measuring a length of a conduit, comprises an air supply device for supplying air into the conduit; a filamentary body including a wire and a plurality of elastic large-diameter members attached to the wire; and a device for detecting that a forward end of the filamentary body arrives at an outlet end of the conduit, where the length of the conduit is measured from the length of the filamentary body inserted into the conduit.

Abstract: Method of testing the functionality of condensate dischargers. Any ultrasonic vibrations present in the condensate discharger are picked up with an ultrasonic vibration sensor and transformed into an electric output signal. The latter is compared in an evaluation unit with stored data. A test result is then formed based on predetermined decision criteria. The test is carried out over a predetermined test duration, within which instantaneous values of the ultrasonic vibrations are picked up at predetermined times and, if need be, smoothed. The test result is based on the instantaneous values.

Abstract: A method and apparatus for the nondestructive evaluation of ferromagnetic and non-ferromagnetic materials, particularly wire ropes, cables, and strands, and pipes utilizing the magnetostrictive effect for measuring minute variations in magnetic fields and characterizing these minute variations as indicative of the acoustic/ultrasonic behavior of fractures, cracks, and other anomalies within a substance under evaluation. The apparatus and method contemplate both an active testing application, wherein a transmitting sensor generates an acoustic/ultrasonic pulse within a material through the magnetostrictive effect and a second receiving sensor detects reflected acoustic/ultrasonic waves within the material, again by the inverse magnetostrictive effect. The advantages of utilizing magnetostrictive sensors as opposed to well known piezoelectric sensors lies in the ability to generate and detect acoustic/ultrasonic waves without a direct physical or acoustical contact to the material.

Abstract: A vibration and acoustic sound diagnostic instrument for use by a professional automotive maintenance mechanic which is capable of discriminating audible vibration sound and noise generated by under-chassis and under-hood parts and devices having mechanical faults. The instrument includes at least one acoustic vibration pick-up device adapted for mounting in contact with an automotive part or device for detecting and converting vibratory acoustic signals and sounds into electromagnetic signals and an electronics housing conformed to be held in the hand of the maintenance mechanic. Pre-amplifier circuitry within the housing is electrically coupled to the acoustic vibration pick-up device and to range selector circuitry for selecting sound level ranges respecting the electromagnetic signals. A decibel meter, mounted to the exterior of the housing, is electrically interconnected to the pre-amplifier for visually indicating changes and peaks in the sound levels detected by the transducer microphone.

Abstract: A detection method and system utilizing silicon models of the traveling wave structure of the human cochlea to spatially and temporally locate a specific sound source in the presence of high noise pandemonium. The detection system combines two-dimensional stereausis representations, which are output by at least three VLSI binaural hearing chips, to generate a three-dimensional stereausis representation including both binaural and spectral information which is then used to locate the sound source.

Abstract: An apparatus and process for determining the existence and location of a leak in an underground pipe, comprises a plurality of remote acoustic transmission sensor units distributed along the pipe and each containing equipment for analyzing acoustic signals from the pipe. The equipment includes a mechanism for identifying acoustic features of the acoustic signals which distinguish the acoustic signals of a leak from ambient acoustic signals. A control unit is connected to each of the remote units and includes additional equipment for further analyzing the signals to determine the proximity of the signal to a particular remote unit and, using the amplitude of the signal and the transmission characteristics of the pipe, determining the location of the leak.

Abstract: Buried fluid containing conduits, such as natural gas lines, are located by providing variable frequency sinusoidal excitation acoustic signals over a broad frequency range to the fluid content of the conduit so that the conduit will vibrate and cause elastic vibration in the media in which such conduit is buried. A plurality of measurements of said vibrations are taken on the surface of the media or ground in which such conduit is buried. The measurements are taken laterally of the estimated position of the conduit. The position of the conduit is determined by changes in the characteristics of the vibrations caused by the differences in distances between the pipe and the measurements.

Abstract: A rotary displacement compressor has an adjustable regulator (22) which determines the internal volume ratio of the compressor. The regulator (22) is adjusted in response to the sound level of a sound of compressed working medium, which is sensed by a sound sensor (26) located adjacent to the outlet port (20 ) of the compressor.