Abstract: The invention relates to a piezoelectric transducer particularly for use in transit time measurements. The object of the invention is to provide a piezoelectric transducer which ensures an in-phase two-dimensional pulse emission which, independent of the selection of a definite excitation frequency, substantially closely follows the electric excitation at a low time deformation of the pulse owing to transient and dying-out operations and which permits to obtain sufficiently high sound levels at low amplitudes of the excitation voltage.

Abstract: An acoustic wave transducer useful in sonic logging while drilling a borehole through an adjacent earth formation includes an array of transducer elements mounted circumferentially around a drill collar. The elements are bonded in an elastomer ring that is received in an external groove in the collar and are protected by a shield having windows. The elements are electrically connected in parallel so that when excited by an electrical pulse, the elements generate a monopole acoustic wave that propagates out into the formation. When used as a receiver, the electrically connected array of elements detect averaged acoustic waves from the formation around the circumference of the drill collar and have minimum sensitivity to acoustic multipole waves traveling through the drill collar.

Abstract: An opto-acoustic detector includes a fiber laser having a cavity which includes an optical fiber having an active medium portion doped with a gain material so that the detector may be used in high frequency, high density arrays. The cavity is bounded by a frequency selective reflector and a broadband or frequency selective reflector adapted to be acoustically coupled to a medium supporting ultrasound radiation (i.e. acoustic waves). In one embodiment, the frequency selective reflector is a diffraction grating placed external to the optical fiber. In another embodiment, the frequency selective reflector is a narrowband reflector placed directly in the optical fiber. An acoustic signal enhancing feature which increases sensitivity of the detector is provided by utilizing a reflective membrane having a thickness substantially less than the acoustic wavelength, .lambda., as the broadband optical reflector.

Abstract: A method and an apparatus for nondestructive detecting and evaluating chas in the microstructural properties of a material by employing one or more magnetostrictive transducers linked to the material by means of one or more sonic signal conductors. The magnetostrictive transducer or transducers are connected to a pulser/receiver which in turn is connected to an oscilloscope. The oscilloscope is connected to a computer which employs an algorithm to evaluate changes in the velocity of a signal transmitted to the material sample as function of time and temperature.

Abstract: An apparatus for conducting ultrasonic waves to and from a body of a molten material. The apparatus includes a buffer rod for transmitting ultrasonic waves to the molten metal, a second buffer rod for receiving ultrasonic waves from the molten metal, piezoelectric elements associated with each buffer rod, and cooling mechanisms for protecting the piezoelectric elements by maintaining the buffer rods at a prescribed rate of thermal equilibrium with the molten metal. The cooling mechanisms are configured so as to facilitate regulation of the air flow about the apparatus.

Abstract: An elastic wave position-sensing device comprising at least two elastic wave transducing units X and Y having N propagation lanes U.sub.Xi, (i=1, 2, . . . , N) and U.sub.Yi (i=1, 2, . . . , N), respectively, a nonpiezoelectric plate, a display panel mounted on one end surface of the nonpiezoelectric plate, and a controlling system connected with the units X and Y. Each unit includes a piezoelectric substrate P.sub.T, a piezoelectric substrate P.sub.R, at least an input interdigital transducer formed on one end surface of the piezoelectric substrate P.sub.T, and at least an output interdigital transducer formed on one end surface of the piezoelectric substrate P.sub.R. Each piezoelectric substrates mounted on one or the other end surface of the nonpiezoelectric plate and the nonpiezoelectric plate form N bilayer zones L.sub.Ti (i=1, 2, . . . , N), a bilayer zone L.sub.R, and a monolayer zone between the bilayer zones L.sub.Ti and the bilayer zone L.sub.R. When an electric signal E.sub.

Abstract: A sheet material detector has an ultrasonic transmitter and an ultrasonic receiver spaced from one another to permit the passage of a sheet of material therebetween in use. The transmitter and the receiver are mounted on a support to transmit and receive the ultrasonic beam respectively along an axis which is at an acute angle, preferably in the range from 50.degree. to 70.degree., in relation to the plane of the sheet material in use, and each of the transmitter and the receiver includes a hood for shielding the ultrasonic beam against contamination by stray sound waves reflected from extraneous bodies or at the surface of the web or sheet. The detector also includes output signal responsive to the received ultrasonic beam for generating an output signal. One application of the detector is in splice detecting apparatus for detecting the presence of splices in a web of material, and another application is in edge detecting apparatus for indicating the position of an edge of the web or sheet of material.

Abstract: A multilayer composite transducer is disclosed. The multilayer composite transducer comprises a plurality of layers wherein a piezoelectric material is dispersed periodically within a polymer matrix. The piezoelectric material is typically formed into columns or slabs, and these columns and slabs need to be aligned from one layer to the next. As this alignment can be difficult to perform, the present invention teaches a first method for fabricating the multilayer composite transducer which allows the alignment to be easily accomplished and a second and third method which reduce or eliminate the need for the alignment.

Abstract: A device and method for determining the radial pressure profile of a wound roll of material uses internal and external sensors to measure the time of flight of an acoustic wave induced within the roll by sharply impacting the surface, or by impacting a member in contact with the surface. The wave measurements are then fed to a computer which uses a modification of Hakiel's model to compute the radial pressure profile.

Abstract: The remote inspection of seam welds in reactor vessels is improved through the utilization of a pulser network which is inductively isolated from the transducer circuit to which it applies an excitation signal. Through the utilization of a step-up transformer, the pulser network may perform in conjunction with linear d.c. power supplies of lower voltage rating. The inductive coupling between circuits also serves to provide for the positive commutation off of switching devices such as SCRs employed for excitation signal triggering. To avoid ground path induced noise, a different ground path is employed for the pulser network as for the transducer circuit. The transducer circuit ground path is that associated with a manipulator and, for example, a reactor vessel itself. Thus, the transducers employed may come in contact with the surface of the vessel being inspected. In similar fashion, an inductive coupling is provided between the transducer circuit and a pre-amplfying receiver circuit.

Abstract: A method for regulating the thickness of several individual layers of an extruded multilayered plastic web involves melting at least two currents of molten plastic in different extruders and bringing the individual molten currents together in an adapter wherein the currents are superimposed into a laminated extruded multilayer stream. The extruded multilayer stream is supplied to a die slot. Devices are provided for controlling the flow of individual currents of molten plastic by modifying their sections before the currents are brought together in the adapter. In order to regulate the thickness distribution, the thickness of the individual layers of the multilayered extruded stream, which correspond to the different currents of molten plastics, is determined before the stream leave the die slot; that is, while the currents are still in a plastic state.

Abstract: A sensor system includes an ultrasonic transducer head with plural transducing elements. The elements are arranged in pairs with the first one of each pair lying in a first plane and the second one of each pair in a second plane spaced a half wavelength away. For transmission, the two are driven out of phase, while for reception their outputs are combined differentially. By changing the drive frequency the transmitted beam is steered to compensate for changes in transducer alignment, or changes in acoustic path caused by abnormal temperature, pressure or flow velocity. In another embodiment, an assembly has a plurality of transducers aligned along slightly divergent paths. Preferred systems employ an upstream and a downstream transducer assembly, each of which is used to alternately transmit and receive signal energy.

Abstract: An acoustic emission transducer consists of a resonant detection element (10) which is attached to the base-plate (16) by a small area in comparison to the overall surface area of the resonant detection element (10) where this area of attachment is positioned with respect to the wave motion during the resonance of the resonant detection element (10) so as not to have a significant effect on the resonant detection element (10) other than to physically couple the resonant detection element (10) to the baseplate (16) and introduce elastic waves from the baseplate (16) to the resonant detection element (10) at the desired frequency, while allowing damping materials (24) to be acoustically coupled to the larger part of the resonant detection element surface area to produce a resonant acoustic emission transducer having reproducible characteristics of resonant frequency and rate of damping.

Abstract: An ultrasonic parametric amplifier incorporates a duct having rigid cylindrical wall with a periodic inner surface that undulates sinusoidally in an axial direction, and an element for heating the external surface of the wall. The sinusoidal undulations of the periodic inner surface have a wavelength which is about half of the wavelength of the waves of ultrasonic energy propagating through a fluid filling the duct. The waves are amplified by synergistic interactions of the ultrasonic waves with the periodic duct walls when heat is added in a predetermined manner, thereby compensating for the exponential decrease in fluid temperature which would otherwise lead to detuning of the amplifier.

Abstract: A soft membrane booted transducer for performing ultrasonic inspections of parts and components that have rough sound beam entry surfaces. These rough surfaces may be in the form of as-welded unprepared overlays, cladded components, as-cast parts, or other unprepared surfaces that tend to prohibit, or prevent, sound entry from normal, smooth, hard-surfaced transducer contacting shoes made from Lucite or similar materials. The booted ultrasonic transducer has a soft membrane boot for coupling the transducer to an uneven or rough sound beam entry surface. The soft membrane is made of a flexible material capable of transmitting ultrasonic waves. When pressed into contact with the uneven or rough surface of the object being inspected, the membrane flexes to generally conform to the shape of the contacted surface. Flexing of the membrane eliminates or reduces air gaps between the transducer and the object surface, thereby increasing the ultrasonic coupling between the piezoelectric element and the object.

Abstract: An ultrasonic fixture assembly for holding multiple ultrasonic transducers includes a mounting support rod for attaching the fixture assembly to a manipulator of a ultrasonic inspection system. A plurality of transducer mounting blocks may be mounted to the support rod by an elongated mounting bar or a single transverse mounting block may be mounted to the support rod. Each of the transducer mounting blocks will have a channel formed therein for slidably receiving an ultrasonic transducer or if a single transverse mounting block is used a plurality of channels will be formed through the mounting block. A central channel or a central transducer mounting block is provided for receiving and retaining a longitudinal wave type ultrasonic transducer and other channels or transducer mounting blocks disposed on either side of the longitudinal transducer are formed to hold shearwave type transducers.

Abstract: Presented is a method and apparatus for inspection through use of a variable angle ultrasonic transducer of metallic members such as pipes, conduits, plates and other formed metallic members normally having a surface regularity adhering to a predetermined standard of normalcy. Inspection proceeds in such a manner that irregularities in the surface of the member under test that lie outside the standard of normalcy are sensed, the degree of irregularity determined and converted into an electrical signal that is applied to continually variably control the angular relationship of the ultrasonic transducer with the surface of the metallic member being inspected whereby abnormalities within the metallic member may be reliably and accurately detected, displayed and recorded.

Abstract: An optical transducer, such as used in an ultrasound system, includes a signal laser which generates an optical signal the frequency of which varies in correspondence with acoustic energy incident on the transducer. An optical cavity in the signal laser is disposed such that incident acoustic energy causes compression and rarefaction of the optical cavity, and this displacement varies optical frequency generated by the laser. A laser pump coupled to the lasing medium is adapted to apply selected levels of excitation energy appropriate to the generation and detection of acoustic pulses. The signal laser alternatively is adapted such that the refractive index of the optical cavity is varied in correspondence with the incident acoustic energy to modulate the optical frequency of the light generated by the signal laser.

Abstract: In a blown film extrusion system in which film is extruded as a tube from an annular die and then pulled along a predetermined path, an apparatus is provided for gauging and controlling the circumference of the extruded film tube. At least one transducer, preferably ultrasonic, is mounted adjacent the extruded film tube for transmitting and receiving interrogating pulses along paths normal to the extruded film tube, and for producing a current position signal corresponding to the circumference of the extruded film tube. The current position signal is continuously compared with at least one previous position signal, preferably with a computer program resident in a controller memory. If at least one preselected condition is violated, the current position signal is disregarded in favor of an estimated position signal.

Abstract: A transducer for generating or detecting ultrasonic energy of very narrow bandwidth which closely approximates a monochromatic source or detector has a gas gap of uniform dimensional width. The transducer employs standing ultrasonic waves generated, by multiple reflections and constructive interference, within the gap, effectively acting as a filter to pass only ultrasonic waves having a predetermined resonant frequency in response to impingement of broadband ultrasonic energy. This filtering effect enables the transducer to act as a source or detector of monochromatic ultrasound.

Abstract: A method for simulating in real-time the ultrasonic inspection of flaws in power plant components such as piping stores the X, Y and skew data relating to a specific waveform and a specific flaw in a unique format in a multi-disk rotational data storage. The skew angles are respectively stored on one side of a disk with the X-axis data relating to tracks on the disk and the Y-axis data to sectors on the disk. In this manner waveform data of several bytes which represent a defect or flaw can be retrieved and displayed to the user of this simulation system. A RAM is utilized as a cache memory.

Abstract: An ultrasonic probe device has an ultrasonic transducer unit including a plurality of ultrasonic transducer elements electrically isolated from one another. A backing member for mechanically damping the ultrasonic transducer unit is arranged on the ultrasonic transducer unit. A plurality of signal lines is connected to the transducer elements, respectively, and extends on the backing member. The backing member is molded from a composition containing rubber material and a metal oxide which is unreducible by the heat applied during a molding process of the backing member.

Abstract: The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses.

Abstract: An apparatus and method for aiming an ultrasonic transducer is disclosed. A tubular member having an axial bore with the transducer extending therein has an upper section, and a lower section with a threaded outer surface and an inner receiving surface. A ferrule assembly includes a compression nut mating with the threaded surface, and a ferrule biased by the compression nut against the receiving surface to form a waterproof seal with the transducer. A collar having a first annular section is detachably mounted coaxially on the tubular member. The first annular section extending to a second annular section having cut-outs suitable for providing access to manipulate the compression nut. The second annular section extending to a third annular section having a positioning members facing a section of the transducer extending from the tubular member.

Abstract: An ultrasonic piezoelectric transducer that is operable in very high and very low temperatures. The transducer has a dual housing structure that isolates the expansion and contraction of the piezoelectric element from the expansion and contraction of the housing. Also, the internal components are made from materials having similar coefficients of expansion so that they do not interfere with the motion of the piezoelectric element.

Abstract: An acoustic-emission sensor includes a composite synthetic resin-ceramic piezoelectric element which has a plurality of substantially mutually parallel columnar ceramic piezoelectric bodies. The columnar ceramic piezoelectric bodies are polarized in a longitudinal direction and are disposed in a synthetic-resin matrix. Since only longitudinal waves can be detected from among acoustic-emission waves, an intensity and variation in intensity can be detected accurately.

Abstract: An ultrasonic piezoelectric transducer and a method for measuring and/or monitoring various physical properties of a member, in-situ, are disclosed. The transducer includes a sleeve which is received in a blind bore provided in the member, a piezoelectric element positioned within the blind bore, and an aligning spacer means interposed between the end of the sleeve and the piezoelectric element. By the application of appropriate voltage pulses to the piezoelectric element causing interrogating signals to be applied to the member, and the measurement of the time interval between the application of an interrogating signal and the receipt of a return signal from the member, various physical properties of the member and structural information regarding same can be determined.

Abstract: A tube inspection station includes a receptacle having walls defining a cavity for holding energy coupling liquid and receiving an object to be inspected in the liquid. At least one wall of the receptacle has a longitudinal bore defined and extending therein from an opening at the top thereof above the cavity and a transverse bore extending through the wall. The transverse bore intersects with the longitudinal bore and opens at both interior and exterior surfaces of the wall. The station also includes a transducer operable for sending waves of energy from its first end into the cavity toward the object and receiving echos of energy at the first end from the object for measuring a parameter of the object. Also, the transducer is operable for transmitting input and output signals at its second end.

Abstract: An ultrasonic detection system having a flat faced radiator for providing a narrow beam of ultrasonic energy with minimal dispersion. The system includes an ultrasonic transmitter and receiver unit coupled to an ultrasonic transducer for producing ultrasonic energy. The system also includes a planar radiator and a coupling device between the ultrasonic transducer and the planar radiator. An encapsulating member surrounds the ultrasonic transducer for damping ultrasonic energy transmitted by the transducer in all but one direction. The encapsulating member is also coupled to the planar radiator in areas of the planar radiator that are not coupled to the coupling means. The encapsulating member has an area of increased density immediately adjacent to the planar radiator for damping the ultrasonic energy in areas of the planar radiator that are not directly coupled to the coupling means.

Abstract: A method and apparatus for detecting a blockage in a cored passage of a hydraulic valve casting includes a sound generating device disposed within the spool bore and communicating with the passageway so that a sound wave may be introduced into the passageway and a sound detecting device disposed within the spool bore and communicating with an opposite end of the passageway so that the level of sound transmitted through the passageway may be detected.

Abstract: Various configurations of cylindrically shaped transducers are used as borehole seismic wave sources. The basic class of transducers of this invention has an outer shell that is generally cylindrical, and may be comprised of cylindrical sections. The shell or the sections may be pre-stressed or preformed to encourage certain bending motions. Depending on the configuration of the transducer, it approximates a monopole, dipole, or quadrupole radiator. Various actuating means, including magnetostrictive forces and piezoelectric forces, are used to drive the motions of the transducer. These transducers are especially useful for generating compressional, shear, or other elastic waves in solids. For example, in geophysical applications, the transducers are placed in boreholes for either hole-to-hole or single hole measurements.

Abstract: In a blow film extrusion system in which film is extruded as a tube from an annular die and then pulled along a predetermined path, an apparatus is provided for gauging and controlling the circumference of the extruded film tube. At least one transducer, preferably ultrasonic, is mounted adjacent the extruded film tube for transmitting and receiving interrogating pulses along paths normal to the extruded film tube, and for producing a current position signal corresponding to the circumference of the extruded film tube. The current position signal is continuously compared with at least one previous position signal, preferably with a computer program resident in a controller memory. If at least one preselected condition is violated, the current position signal is disregarded in favor of an estimated position signal.

Abstract: An apparatus for investigating a sample with ultrasound has a probe head formed by a casing, a transducer element of piezoelectric plastics material, and a source for applying a high frequency pulse to the sample. The source is preferably one end of an optical fibre, which fibre extends to a laser remote from the probe head. The transducer element is connected to the sample by an acoustic coupling medium, e.g. water. Thus, the probe head can be moved relative to the sample, and a compact, but efficient, structure is achieved.

Abstract: An ultrasonic contact transducer for point-focussing surface waves having a narrow beam width and a high sound intensity at a focal point in order to obtain better resolution and high beam intensity, which is applicable to the nondestructive testing technique of the surface or subsurface of a specimen to be tested, is disclosed. The ultrasonic contract transducer generates surface waves, focuses the waves at one point on the surface of the specimen and receives again the signals scattered from the surface flaws or subsurface flaws of the specimen, in order to detect the surface cracks, surface flaws, subsurface flaws of the specimen and to detect the delamination in a thin laminated film.

Abstract: A transducer is constructed of a cylindrical shell and at least one pair of piezoelectric sections. Each member of the pair of piezoelectric sections is rigidly bonded to the wall of the cylinder, in a position diametrically opposed from the other member of the pair. Operation as an acoustic source transducer is accomplished by electrically energizing each piezoelectric section in such a manner as to cause the piezelectric sections to elongate and contract, respectively out of phase with one another, along the cylinder length. This causes flexural bending of the cylinder, with the bending being asymmetrical with respect to the cylinder axis. When one pair of piezoelectric sections is used in this manner, the transducer approximates an acoustic dipole radiator, and if more than one pair is used, the transducer can be used to approximate higher order polarized acoustic radiators.

Abstract: An ultrasonic measuring device for determining motion parameters of moved bodies, in particular path, speed, acceleration, slip and the like, comprising first and second ultrasonic transducers supported in a housing. Each of the ultrasonic transducers (transmitter and receiver) having either a sound generator or a sound receiver positioned between two vibrating elements. A connecting element clamps a sound generator with a sound receiver between the vibrating elements. Each of the ultrasonic transducers being supported by support elements featuring bent-off portions arranged in a meander-type manner in turn (bent back upon itself) in the housing. One of the support elements, for each transducer, is arranged at the sound opening of the housing and is slidably mounted on a vibrating element.

Abstract: An ultransonic transducer includes a vibrator positioned within a housing. The vibrator has a vibrator casing and a vibrator element or oscillation body. The vibrator casing has a wall defining an internal space receiving an electronic transducer circuit. The vibrator casing is elastically damped for stabilizing vibration within a minimum period so that vibration for generating an ultrasonic wave may not influence detection of the ultrasonic wave reflected by an object. The electric transducer circuit is also elastically isolated from the vibration casing via an elastic cover so as to avoid influence of the vibration of the vibrator, and connected to the oscillation body for generating and receiving signals.

Abstract: A method and apparatus for nondestructive material characterization, such as identification of material flaws or defects, material thickness or uniformity and material properties such as acoustic velocity. The apparatus comprises a pulsed laser used to excite a piezoelectric (PZ) transducer, which sends acoustic waves through an acoustic coupling medium to the test material. The acoustic wave is absorbed and thereafter reflected by the test material, whereupon it impinges on the PZ transducer. The PZ transducer converts the acoustic wave to electrical impulses, which are conveyed to a monitor.

Abstract: An ultrasonic probe has a piezoelectric vibrator composed of an array of piezoelectric vibrator elements, and an electrode plate having as many electrode patterns as the number of the piezoelectric vibrator elements. The piezoelectric vibrator elements and the electrode patterns are electrically connected to each other by an auxiliary electrode plate disposed therebetween. A method of manufacturing the ultrasonic probe is also disclosed.

Abstract: An acoustic sensor assembly for a microwave oven of the type having an oven cavity defined by walls. The acoustic sensor assembly comprises an acoustic sensor for converting sound into an electrical signal representative thereof, and aperture in the wall of the microwave oven cavity of sufficiently small to prevent microwaves from passing therethrough. The assembly further includes a hollow conduit, for example a plastic tube, having first and second ends and secured to the aperture at the first end and to the sensor at the second end for acoustically coupling the sensor to the aperture such that sounds in the cavity are passed through the aperture to the sensor.

Abstract: An ultrasonic transducer assembly for monitoring the quality of spot welds employs a transducer element joined to a support element and fitted within a conventional welding electrode assembly. The transducer assembly is biased against the interior surface of the welding electrode tip by a biasing element, preferably a compression spring. A sleeve, preferably composed of brass, surrounds the transducer element and is joined to the support element. A coaxial cable in communication with external instrumentation has a ground lead attached to the sleeve, and a signal lead attached to the transducer element.

Abstract: A method of making an ultrasonic probe having a piezoelectric vibrator composed of an array of piezoelectric vibrator elements, and an electrode plate having as many electrode patterns as the number of the piezoelectric vibrator elements. The piezoelectric vibration elements and the electrode patterns are electrically connected to each other by an auxiliary electrode plate disposed therebetween.

Abstract: In an ultrasonic inspection method and apparatus for inspecting the presence or absence of a defect in an object to be inspected by receiving as an RF signal a reflection beam of an ultrasonic beam emitted from a probe to the object and displaying data of the RF signal on a display unit, a maximum value indicative of a positive peak of the RF signal is detected, a maximum absolute value indicative of a negative peak of the RF signal is detected, a computation is performed for comparing in magnitude the maximum value indicative of the positive peak with the maximum absolute value indicative of the negative peak, and a computed value is displayed on the display unit so that the presence or absence of a phase inversion of the RF signal may be judged for deciding the presence or absence of a defect in the object.

Abstract: A detecting apparatus using ultrasonic waves comprises a sensor unit and a signal processing unit for processing a reception signal sent from the sensor unit to output a detection signal. These units are connected by a cable having three core wires. A power supply signal, an ultrasonic transmission signal and operation indication signal are multiplexed to the first core wire and transmitted from the signal processing unit to the sensor unit. An ultrasonic reception signal and a temperature detection signal are multiplexed to the second core wire and transmitted from the sensor unit to the signal processing unit. The third core wire is used to connect the grounding levels of both units.

Abstract: An apparatus for the remote examination of peripheral shroud hold down bolts on steam separators used in boiling water reactors is disclosed. The testing apparatus is used while the steam separator is in a holding pool. The testing apparatus includes a depending pole having attached at the bottom thereof an aluminum shoe. The shoe has a flat, upwardly exposed bottom and opens to one side at gathering surfaces to receive the lower ends of the shroud bolts. The upwardly exposed bottom of the shoe defines an aperture through which an upwardly exposed piezoelectric device is exposed for direct contact with the bottom of the bolt. An overlying clamp member is provided to clamp the lug onto the bottom of the shoe for testing. The clamp member defines a receiving slot to receive the shaft of the bolt immediately overlying the rectangular lug. The clamp member slides over the shaft at the slot into contact with the top of the lug.

Abstract: A sensor for acoustic shockwave pulses, such as in lithotripsy, includes a piezo-electric measuring membrane disposed between two coupling membranes. The intervening space between the coupling membranes is filled with a coupling medium for transmitting the acoustic shockwave pulses. The measuring membrane is in a defined condition largely independent of external influences so that flows in the coupling medium or different pressure exertions on the two coupling membranes do not influence the measured signal produced by the measuring membrane.

Abstract: An ultrasonic air spring system adapted to be mounted on a vehicle for absorbing road shocks exerted on the vehicle and for maintaining the vehicle body level with respect to the axles. An air spring includes an end plate and a piston sealingly connected to the open ends of the flexible elastomeric sleeve to form a pressurized fluid chamber therebetween. A transducer is mounted on the end plate within the fluid chamber and transmits ultrasonic signals through the fluid chamber toward the piston and picks up reflected signals therefrom. A signal is generated by the transducer in response to the reflected signals and fed to a microprocessor based control module. The control module determines whether the air requires fluid feed or exhaustion and will then implement control of inlet or exhaust valves to achieve a desired axial separation between the end plate and piston.

Abstract: Apparatus for sensing the thickness of a pulp suspension, having zones or slices, on the forming wire of a paper making machine includes an array of ultrasonic transducers located in the apertures of a structural member mounted in a cross-direction under the forming wire near the headbox of the machine. Each ultrasonic transducer is mounted on a flexible sheet which is mounted to an aperture and the transducer moved into close proximity to the bottom of the forming wire by means of air pressure in the structural member. A second array of transducers downstream of the first can be utilized for diagnostics.

Abstract: An ultrasonic transducer for coupling ultrasonic energy to a web-like porous sample includes a sample-contacting layer of soft neoprene, 5-15 durometer hardness, which conforms to the surface of the sample being tested when pressed thereagainst. A non-polarized backing layer of polyvinylidene fluoride eliminates reflections at the end of the transducer remote from the sample. A polystyrene impedance-matching layer is located between the sample-contacting and the backing layer to provide a low-loss, low-impedance coupling of ultrasonic energy to the sample-contactiong layer. A stack of two, and preferably four, metallized polyvinylidene fluoride films is located between the impedance-matching layer and the backing layer. The outer surfaces of the stack are grounded, while the inner surfaces are energized by the ultrasonic energy source. The outer layers are polarized in a first direction, opposite that of the polarization direction of the middle layer.

Abstract: Leaks or thin spots in containers, as well as mechanical faults, e.g. worn bearings, are detected by an ultrasonic energy indicator that includes a modulator that heterodynes ultrasonic signals received by a transducer and creates an audio signal related thereto. The transducer includes a series arrangement of piezoelectric crystals feeding a field-effect transistor amplifier and the modulator operates in an amplitude modulation, suppressed-carrier mode which can be stabilized by a feedback loop. For indicating the presence of the audio signal, either headphones or a meter or both are employed. When leaks in a container are being detected, an ultrasonic generator is used which varies its output frequency slowly over a band of frequencies. The leak detection technique can be improved by applying a thin layer of a liquid to the container surface so that pressure introduced into the container causes the formation and bursting of bubbles in the liquid that results in the production of ultrasonic energy.