Abstract: A system is disclosed for performing vibrational resonance ultrasonic Doppler spectrometry to produce characteristic vibrational resonance spectra of soft structures in compressible media or soft tissues in a living body. A system is further disclosed for vibrational resonance ultrasonic Doppler imaging of the spatial distribution of vibrational resonance properties. An audio-frequency source externally applies a sequence of vibrational frequencies into a medium or body. Ultrasonic pulsed Doppler beams are focused at various locations within a region of interest, and the received Doppler signals are used to estimate the amplitude of the vibrational resonance response at each location. A vibrational resonance spectrum is computed from received Doppler amplitudes at each vibrational frequency and graphically displayed.

Abstract: A method for measuring the cover thickness of a reinforcing bar in concrete. An impacting device and a receiver are disposed on the concrete surface along the longitudinal axis of the reinforcing bar with a predetermined distance H provided between the impacting device and the receiver. Then, an impact is applied on the concrete surface by the impacting device, to generate a dilatational wave which propagates into the concrete and is totally refracted at an interface between the concrete and the reinforcing bar, and is received by the receiver. Then, the cover thickness of the reinforcing bar is calculated according to the travel time for the dilatational wave from the impact device through the reinforcing bar to the receiver.

Abstract: An acoustic method and apparatus for measuring the horizontal surface location and depth of any type of underground pipe or conduit, including nonmetallic or nonconductive pipe, such as sewer, gas, and water pipes, which cannot be detected with electromagnetic locators. A continuous-wave (CW) acoustic signal is injected into and transmitted through the fluid (liquid or gas) in the pipe. The horizontal surface location and depth of the pipe are determined from an analysis of the phase measurements derived from an array of acoustic measurements, which are made at the surface and approximately perpendicular to the direction of the underground pipe.

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: A method for determining changes in the average wall thickness or the mean radius of a pipe or tube using ultrasonic and/or magnetostrictive wave probes by analyzing the dispersive behavior of waves traveling in the tube wall volume. The method examines certain wave propagation modes and identifies a cut-off frequency that is characteristic for a particular wall thickness or tube diameter. This method permits the rapid and accurate inspection of a length of pipe or tube from a single location on the inside diameter of the pipe and permits a comparison of data gathered with similar data for the structure in its original condition. Changes in the cut-off frequency, indirectly determined by the method of the present invention are inversely related to changes in the wall thickness and/or the mean radius for the cylindrical structure. In this manner the method of the present invention provides a mechanism for determining the remaining service life for such pipes and tubes.

Abstract: A system for assaying a fluid sample for one or more types of analytes, which employs at least one class of finely divided polystyrene spheroidal particles, each class being limited to a predetermined specific narrow range of particle diameters, the particles of each such class being coated with a specific reactant unique for that class. After the coated particles are mixed with the sample to specifically react to form conjugates of the particles and any of the analyte present, the mixture is irradiated with bursts of ultrasound swept over a range of frequencies resonant to the expected conjugate sizes. The presence of the conjugates and therefore the analyte is detected directly by measuring any selective absorption or scattering of waves of frequencies to which the conjugates are resonant.

Abstract: The density of a discrete piece of hard tissue such as a bone in a patient may be determined by either of two methods. In a first method, an impulse of energy is introduced into the tissue, and the resulting vibration in the hard tissue is sensed and analyzed to compute the modal damping factor of the tissue, the modal damping factor being directly related to the density of the tissue. In a second method, a continuous energy input is introduced into the hard tissue. The resulting vibration in the tissue is measured with a mechano-electrical vibration transducer and a modal damping factor is calculated. The electro-mechanical vibration transducer of the preferred embodiment measures the pressure with which the transducer is pressed against the patient's flesh and only produces the continuous energy input when a predetermined pressure is achieved which is sufficient to prevent any significant vibration of the flesh surrounding the bone.

Abstract: A method of testing the quality of a fruit including applying a dynamic impact force to the fruit, detecting the mechanical response of the fruit to the dynamic force via a piezoelectric film transducer supported on a displaceable resilient base member such that the film transducer is bent by the dynamic impact force, to induce a strain in the film transducer, and the film transducer outputs an electrical signal corresponding to the change of the induced strain in the film transducer caused by the dynamic force and analyzing the electrical signal to indicate the quality of the fruit. Apparatus for carrying out the method is also described and claimed.

Abstract: An apparatus for measuring loss of sound traveled in a muffler of an automobile comprises: a first and second pipe between which the muffler, to be tested, is inserted; a sound source connected to one end of the first pipe opposite to the muffler to create a sound into the first and second pipes; the first microphones mounted at the first pipe to measure the level of sound before the muffler; the second microphones mounted at the second pipe to measure the level of sound after the muffler; and a non-reflect means connected to the second pipe for the sound passing through the first and second pipes so as not to reflect into them.

Abstract: A system for detecting ultrasonic vibrations, such as those generated by a small leak in a pressurized container, vessel, pipe, or the like, comprises an ultrasonic transducer assembly and a processing circuit for converting transducer signals into an audio frequency range signal. The audio frequency range signal can be used to drive a pair of headphones worn by an operator. A diode rectifier based mixing circuit provides a simple, inexpensive way to mix the transducer signal with a square wave signal generated by an oscillator, and thereby generate the audio frequency signal. The sensitivity of the system is greatly increased through proper selection and matching of the system components, and the use of noise rejection filters and elements. In addition, a parabolic collecting horn is preferably employed which is mounted on the transducer assembly housing.

Abstract: An acoustic sensor system for detection of insects in agricultural commodities. The system includes isolation structure for isolating the agricultural commodities from external noise and vibration, an improved acoustic sensor for detecting sound from within the agricultural commodities and for generating a signal in response to sound so detected, and a user recognizable output such as earphones or a light emitting diode for producing user recognizable output in response to signals generated by the acoustic sensor.

Abstract: The fatigue integrity of metallic materials may be determined by either one of two methods. In a first method, an impulse of energy is introduced into the material, such as by striking the material (20), and the induced vibration is sensed and analyzed in order to compute the damping factor thereof, the damping factor being directly related to the fatigue thereof. With this method, a transducer (28) is coupled to the material and its output is amplified by an amplifier (30) before input to a computer (32) which determines the damping factor. In a second method, a continuous energy input is provided to the material, such as by utilizing a frequency generator coupled to a power amplifier whose output drives a transducer such as a speaker or the like for inducing a continuous vibration in the metallic material. This continuous vibration is measured with a transducer, an amplifier, and a damping factor calculated with a computer as in the first method.

Abstract: An apparatus and method for identifying a conduit at a second location remote from a known first location of the conduit, characterized by a vibration device and means for removably coupling the vibration device to a wall of the conduit for transmission of vibration to and/or generation of vibration in the conduit, thereby enabling identification of the conduit at the remote second location.

Abstract: A method and apparatus for detecting the location of subterranean pipe includes sensors 24 and 26 which detect seismic energy. A pulsing valve (20) is disposed on one end of a water line (10) to allow water to intermittently flow and be shut off. This results in a water hammer effect which send shock waves (22) outward from the pipe (10). This is detected by the sensors (24) and (26) and then transmitted to a detector (32) to provide a differential indication. The locations of the sensors (24) and (26) will determine the differential balances therebetween such that when the sensors (24) and (26) are directly over the pipe (10), an indication of the location of the pipe is provided. Further, a reference sensor (19) is provided to allow distance measurement along the pipe by measuring the difference between the received energy at sensor (19) and either of sensors (24) or (26).

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: Columns, walls and other solid structures of concrete, wood, masonry or other materials are non-destructively tested by acoustic signals transmitted from a carriage. The carriage has a frame which is wheel mounted to move over the surface of the test candidate. An internally-mounted piezoelectric crystal roller as an acoustic signal generator or receiver is suspended from the carriage with two degrees of spring freedom to allow accommodation of irregularities in the test candidate surface. The assembly including the piezoelectric crystal roller and its flexible mounting are configured as a replaceable module relative to the carriage frame. The same carriage is useable as an echo type acoustic scanner or, in combination with other devices or carriages, as either an acoustic transmitter or receiver although inclusion of elements to perform both functions within the same carriage is contemplated.

Abstract: The integrity (density) of discrete pieces of hard tissue (bones) in a patient may be determined by either one of two methods. In a first method, an impulse of energy is introduced into the hard tissue, such as by striking the patient's hard tissue, and the induced vibration is sensed and analyzed in order to compute the damping factor thereof, the damping factor being directly related to the density thereof. With this method, a transducer is coupled to the hard tissue and its output is amplified by an amplifier before input to a computer which determines the damping factor. In a second method, a continuous energy input is provided to the hard tissue, such as by utilizing a frequency generator coupled to a power amplifier whose output drives a transducer such as a speaker or the like for inducing a continuous vibration in the hard tissue. This continuous vibration is measured with a transducer, having amplified output, and a damping factor is calculated with a computer.

Abstract: Measurements are taken perimetrically about power or feeder cables at equidistant spaced locations with one or more vibration transducers feeding an electronic measuring circuit sharply tuned to twice the fundamental frequency of the supply system. A substantially flat response around the cable indicates a deenergized cable, while an energized cable produces vibrations that vary sinusoidally in amplitude as the readings progress around the cable.

Abstract: A vibration chamber for screening or testing printed circuit boards by subjecting the printed circuit boards to acoustical vibrations which are generated by top and bottom speakers which face each other, with the printed circuit boards between the speakers. The top and bottom speakers are arranged in a "push-pull" configuration so that the speakers cooperate with one another in pushing air up and down in the vertical plane, thus imparting maximum acoustical energy to both sides (top and bottom) of the printed circuit board under test. The vibration chamber can be mated to a roller conveyor system for automatically running printed circuit boards through the vibration chamber in a production environment, and the speaker system can be driven by a profile of random vibration noise to achieve the maximum number of modes of vibration on the printed circuit board in the minimum amount of time.

Abstract: The length of a column of a gaseous or liquid substance or of a solid bar is determined by generating a standing wave of known frequency, wavelength and/or wave velocity in the column or in the bar. The wave frequency is varied until at least two consecutive maxima (antinodes), two consecutive minima (nodes) or a minimum following a maximum of the amplitude of the standing wave have been detected. The length of the column of medium at known frequency and wave velocity of the standing wave generated in that column is computed from the equationL=c/[2(f.sub.n -f.sub.n-1)] (1),where L is the length of the column of medium, c is the wave velocity, f.sub.n is the frequency of the nth maximum and f.sub.n-1 the frequency of the (n-1)th maximum. Apparatus for implementing the method comprises a loudspeaker 1 mounted in a resonance chamber 2 with a tubular acoustic exit aperture 3.

Abstract: A method and apparatus for testing the operating condition of a check valve directs sound waves into the valve chamber of a check valve assembly and utilizes the collected signals of the reflected sound waves to generate various time lapse data corresponding to the valve disk position and movement, such time lapse data providing an analysis of the condition of the valve assembly.

Abstract: A method for determining the location of a concealed pipe is disclosed. An identifiable acoustic signal is injected into the concealed pipe. The signal propagates along the interior length of the pipe. The signal is detected by an array of detectors positioned at varying distances from the pipe. The detected signal generates voltage outputs from the detectors to a signal processor. The "time-of-flight" of the acoustic signal from the point of generation to the point of detection is measured by the signal processor. The detector measuring the shortest "time-of-flight" is closest to the concealed pipe.

Abstract: There is disclosed a sheet feeding device having at least two vibration members pinching a sheet, which is frictionally driven by the travelling vibration waves generated in the vibration members. The device is further provided with a detector for detecting the state of vibration of the vibration members and generating a signal corresponding to the phase difference between the vibrations. The signal is used for correcting the vibration state of the vibrations members, thus significantly reducing the unevenness in the sheet feeding.

Abstract: In a process for early detection of damage top machine parts, particularly rolling element bearings, vibrations are detected by means of a vibration pickup in order to make it possible to describe the present condition of the machine part as well as to estimate the remaining service life of the machine part. The picked-up signals are broken down into periodically determined stochastic and generally stochastic signal components. The signal components for determining the parameters for the stress of the machine part are examined as a function of time and the ascertained stress parameters are compared with characteristics values for the permissible stress of the machine part for purposes of determining the type of damage and/or for determining the extent of the damage.

Abstract: A method and apparatus for detecting the location of subterranean pipe includes sensors 24 and 26 which detect seismic energy. A pulsing valve (20) is disposed on one end of a water line (10) to allow water to intermittently flow and be shut off. This results in a water hammer effect which send shock waves (22) outward from the pipe (10). This is detected by the sensors (24) and (26) and then transmitted to a detector (32) to provide a differential indication. The locations of the sensors (24) and (26) will determine the differential balances therebetween such that when the sensors (24) and (26) are directly over the pipe (10), an indication of the location of the pipe is provided. Further, a reference sensor (19) is provided to allow distance measurement along the pipe by measuring the difference between the received energy at sensor (19) and either of sensors (24) or (26).

Abstract: A method of diagnosis utilizing a diagnostic locator for detecting sources of electronic circuit malfunction caused by fractured solder connections or other kinetically locatable electronic circuit malfunctions comprises a diagnostic locator using kinetic energy at sonic frequencies which is discriminately applied to particular circuit areas to reveal mechanical intermittance on an accurate basis. The locator includes an elongated non-conductive test probe which is mounted within a housing at one end containing a transducer for kinetically activating the probe. An operator may adjust the kinetic energy being released at the probe tip for greater or lesser propagation upon electronic circuitry being diagnosed. This diagnosis of mechanically malfunctioning electronic circuitry is accomplished while monitoring the output of the circuitry in a conventional manner.

Abstract: A system for detecting the location of an underground portion of a sewer line. A vibration or sound of a predetermined frequency is introduced into an accessible (e.g., above ground) portion of the sewer line. The vibration is allowed to propagate through the sewer line and into the underground portion of the sewer line. The location of the underground portion of the sewer is identified by sensing the vibration by means of a detector located at the ground surface or in an inserted "in ground" device above the underground portion of the sewer line.

Abstract: A colloid analyzer is provided employing a relatively low frequency, low power, continuous "acoustic" wave signal propagated in the direction of spaced electrodes mounted adjacent to the side wall of a chamber or vessel containing a colloid sample. The chamber further comprises a series of probes for respectively sensing the pH, temperature, and conductivity of the sample(s) being analyzed. A piezoelectric transmitter generates the acoustic drive signal. The spaced electrodes in conjunction with an electronic signal processing circuit serves as a receiver and generates an output signal relating to the magnitude and polarity of the zeta potential of the particles being "acoustically" excited by the drive signal. A computer responsive to the signal processing circuit's output signals and/or the vessel probes' output signals alternately develop a graphical output relating to zeta potential, and/or one relating to the surface charge density of the analyzed colloid for given levels of titration.

Abstract: An interface unit for measuring instruments, such as audiometers, which are controlled by a computer, the interface unit being as cost-efficient as possible and setting minimum requirements for the computer hardware and software. This is achieved in that the lines (17 to 19) of the interface unit that are connected to the computer contain d-c isolating couplers (17.1 to 19.1) and are respectively connected with individual decoders (13 to 15) which, in turn, are connected to memories (7 to 9). Control lines lead from these memories to the measuring modules (1 to 3) of a measuring instrument. Such a measuring instrument is usable, in particular, as an audiometer or for establishing the optimum adjustment of a hearing aid to compensate certain hearing impairments.

Abstract: A portable acoustic impedance measuring device 10 is provided for measuring the impedance properties of a panel 12. The device 10 includes a horn section 14 having a flexible plate 18. The plate 18 can assume the curvature of the duct panel 12. The horn section 14 is supported adjacent the panel's surface by a spindle shaft 28 which spans or bridges the inside diameter of the duct 12. The curvature of the plate 18 may be locked to hold the curvature of any of a variety of different panels having various sizes and shapes.

Abstract: A phase-sensitive ultrasonic modulation method for the detection of strain-sensitive spectral features involves the use of an ultrasonic field with well-defined wavefronts and a light beam of spot size less than the ultrasonic wavelength and of linewidth less than that of the spectral feature. When the light wavelength coincides with the wavelength of the spectral feature, the ultrasonic wave shifts, splits, or broadens the absorption lineshapes of the various centers contributing to the spectral feature thereby changing the amplitude or phase of the light beam or emitted fluorescence in synchrony with the ultrasonic field.

Abstract: A rotor blade test apparatus having a striking solenoid to strike a rotor blade to generate an audio signal. A microphone receives the audio signal and applies it to a spectrum analyzer wherein the predominant natural frequencies of the rotor blade are determined.

Abstract: An apparatus for controllably delivering power from a device to a workpiece is useful, for example, in performing qualitative material tests on various materials. In the instant apparatus, a sonic generator means controllably supplies sonic power to a workpiece, causing the surface of the workpiece to erode. A sensing means produces an actual power signal having a magnitude responsive to the power consumed by the sonic generator means. A settable means produces a desired power signal, and a control means compares the desired and actual power signals and supplies motor control signals in response to the respective magnitudes of the power signals and to a tracking time interval signal. In response to termination of the tracking time signal, the control means blocks the motor control signals. A motor means controllably moves the sonic generator means relative to the workpiece in response to receiving the motor control signals.

Abstract: A rock detachment evaluation device (10) having an energy transducer unit 1) for sensing vibrations imparted to a subject rock (172) for converting the sensed vibrations into electrical signals, a low band pass filter unit (12) for receiving the electrical signal and transmitting only a low frequency segment thereof, a high band pass filter unit (13) for receiving the electrical signals and for transmitting only a high frequency segment thereof, a comparison unit (14) for receiving the low frequency and high frequency signals and for determining the difference in power between the signals, and a display unit (16) for displaying indicia of the difference, which provides a quantitative measure of rock detachment.

Abstract: This invention is a fluorescent light testing device. It is difficult to determine which fluorescent light or lights may be weak or on the verge of failing when a plurality of lights are disposed in the same general area. This is particularly true when the lights are of the overhead type and the higher the ceiling, the greater the problem. The present invention is a listening device on an extended boom type member to allow the user therof to readily determine which fluorescent lamp is humming thus indicating weakness or imminent failure so that the same can be replaced both to reduce energy use and to keep the lighting system at peak performance.

Abstract: A method and apparatus for measuring a colloidal potential are described using pulses of ultrasonic energy that are directed along a path within a liquid suspension of colloidal particles. A vibration potential is measured at at least a pair of positions along the path. The positions are known relative to the source of ultrasonic pulses. The vibration potential measurements are then used to derive a colloidal potential which is independent of its attenuation encountered by the ultrasonic energy inside the suspension. In one embodiment several potential measuring probes are used and in another embodiment one probe is moved between predetermined positions.

Abstract: The softness of paper as a function of the number of bonding sites per unit area of the paper is determined by directing ultrasonic energy toward the paper and determining the magnitude of the portion of reflected energy.

Abstract: This invention is concerned with a method and apparatus for measuring the electro-kinetic properties of a liquid which may be a mixture such as a slurry of particles, or a dispersion of droplets. Electrodes are placed in the liquid and an apparatus is provided for applying an alternating electrical potential to these electrodes. The electric field from this alternating potential acts upon the charged elements in the liquid, resulting in the generation of sound at the frequency of the applied electrical potential. By placing a conventional acoustic transducer in a spaced relationship to the electrodes, the acoustic signal is detected and measured. The amplitude of the acoustical signal will be a function of the electro-kinetic properties of the particles or emulsion droplets in the liquid. In its preferred form, the electrodes that are placed in the liquid have a spacial separation of one-half wave length, or odd integer multiples of half wave length of the sound which they generate.

Abstract: The invention relates to a convertor for converting electrical vibrations into mechanical vibrations for non-destructive testing of objects, in particular bonded joints between two or more sheets or between sheets and a honey comb structure. Said convertor comprises a polycrystalline, piezo-electric disc, with mutually insulated electrodes on both head faces. The disc is secured in a supporting element by a suspension with a resilient member pressing centrally through a metal pin against the internal head face of the disc. The supporting element is movably installed into a holder such that the supporting element can be moved from a retracted position in the direction of the extended position until such a position is reached that the piezo-electrical disc is pressured against the object to be tested with a predetermined force.The invention also relates to a method for using the convertor.

Abstract: The invention relates to a method of measuring the dimensions of tools and/or workpieces of metal. The measuring is characterized in that an electro-erosive material-machining discharge in a dielectric is used as transmitter of pressure waves, the time of which through the tool or workpiece to the arrival in at least three well-defined positions is scanned and gives rise to time-responsive current pulses for a digital measuring system.

Abstract: A hammer-type device is driven by a cam and spring arrangement in reciprocating motion to strike a moving train wheel for producing vibrations therein which are used to detect defects in the wheel.

Abstract: Apparatus and method for nondestructive detection of loose parts or faulty onds in sound transducers by measuring erratic second-order nonlinear difference-frequency responses of the test transducer to a pulsed high level dual-frequency sound field produced by a high power projector. Such field may be generated by combining a high frequency carrier signal at frequency f.sub.o with a low frequency tone burst signal at frequency f/2 in a double balanced modulator so as to produce the dual-frequency pulse at f.sub.o +f/2 and f.sub.o -f/2. The test transducer converts the dual-frequency pulse into a plurality of linear and nonlinear frequency components including the difference-frequency f.

Abstract: This invention relates to a method and apparatus for inspecting a non-metallic object by means of impact elastic waves to measure the thickness of the non-metallic object such as a concrete structure, solid, etc. or to detect foreign matter contained therein. Impact elastic waves are propagated into the non-metallic object by striking an impact plate mounted thereupon with a hammer or the like.

Abstract: A fast and reliable method is disclosed for measuring the dynamic mechanical properties of a material, particularly its modulus of elasticity and loss factor. By this method the acoustic characteristics of a material can be determined. An elongate strip of material, whose properties are desired to be known, is provided with miniature accelerometers fixedly secured to its opposite ends. One end of the strip is excited by a random noise source which travels toward the other end where that end and accelerometer is allowed to move freely (unrestrained). The accelerometers measures the ratios of acceleration at two locations over an extended frequency range of 0.2 Hz to 25 KHz, and the information is processed through a fast fourier transform spectrum analyzer for determining amplitude of acceleration ratio and phase difference between the two accelerometers from which Young's modulus and loss factor for that material are determined.

Abstract: The invention relates to a method and device for detecting changes in the mechanical state of the members of a structure implanted in the sea, whereby each member is subjected to impacts and after each impact, the simultaneous signals of excitation and dynamical response of the member are recorded, the signals of identical frequency being processed in order to define a ratio which varies with the frequency and presents peaks. The aforesaid operations are repeated at regular intervals, a watch being kept for any shifts in the peaks which could indicate a change in the structure.

Abstract: An improvement to ultrasonic probes useful in the non-destructive testing of structural materials includes a compact, high-sensitivity coaxial design probe. The probe has a centrally located transmitter point and a circumferentially arranged receiver ring. The geometrical relationship between the transmitter point and the receiver ring provides for high-sensitivity in the detection of defects and allows for a compact construction without orientational sensitivity. A receiver tube is provided which encloses the probe and acts as a tuned wave guide for the detection of ultrasonic vibrations from the structural material under test. The increased sensitivity of the improved ultrasonic probe is advantageous in the testing of non-metallic structural materials having a complex composite structure. The compactness of the improved ultrasonic probe is advantageous in the testing of structural materials having complex and narrow shapes.

Abstract: Encoding apparatus for a business machine includes a resilient striker for inducing diverging sound waves within a rod by impact with it at a given location. Transducers positioned along the rod on each side of the striker and at unequal distances from it, convert the sound wave fronts into a first and a second output signal having a predetermined time interval between them which is dependent upon the location of impact with the rod. The transducers are connected to a logic unit which includes an oscillator-driven binary counter. The first output signal starts the counter and subsequent arrival of the second output signal determines the elapsed time, the counter output at that instant being a binary code value usable for any desired purpose: control, display, etc.

Abstract: Piezoelectric transducers are mounted on support members of a gag press for sensing pressure vibrations arising in a workpiece in part as reflections of an initial pulse produced by the striking of the workpiece by a press ram at the initiation of a straightening operation. An electrical circuit is connected to the transducers for analyzing the sensed pressure waves and for comparing the analyzed waves to pre-established sound-threshold data stored in a memory. Upon detecting pressure waves indicative of an internal structural flaw in the workpiece, a microprocessor in the electrical circuit signals a ram drive to raise the ram and thereby terminate straightening operations, the defect-bearing workpiece being transferred to a scrap store or to a heat treatment plant by a sorter according to signals from the microprocessor.

Abstract: A method and apparatus for measuring the dynamic material constants of rur compounds. The rubber compound is tested in strip form by attaching one end of the strip to an electromechanical shaker while the opposite end of the strip is suspended under constant tension. The electromechanical shaker propagates an acoustic wave in the test strip and a piezoelectric transducer positioned at a first point on the test strip measures the mechanical response of the strip for phase and amplitude. The shaker is programmed to step piecewise over the frequency range from 100 Hz to 40 KHz by a frequency synthesizer. The distance between the shaker and the transducer is changed and data is obtained for a second point on the strip. The test values obtained are used to calculate Young's Modulus and the loss factor for the rubber compound.

Abstract: A crystalline bar is doped with a rare earth. The bar is transparent to ration, such as from a laser, at a light wavelength which excites the rare earth ions in the bar and the light is modulated at the frequency at which the bar mechanically resonates.The excited ion decay radiatively by light or non-radiatively by phonons. As the phonons decay, they excite the bar to resonate mechanically. The mechanical resonance may be coupled by a piezoelectric material and measured to give information respecting the phonon activity of the excited rare earth ions.