Abstract: A method is provided for measuring the residual stress in metals. The method includes the steps of drilling one or more holes in a metal workpiece to a preselected depth and mounting one or more acoustic sensors on the metal workpiece and connecting the sensors to an electronic detecting and recording device. A liquid metal capable of penetrating into the metal workpiece placed at the bottom of the hole or holes. A recording is made over a period of time (typically within about two hours) of the magnitude and number of noise events which occur as the liquid metal penetrates into the metal workpiece. The magnitude and number of noise events are then correlated to the internal stress in the region of the workpiece at the bottom of the hole.

Abstract: Electromagnetic acoustic resonance method by using EMAT is used for determining hydrogen concentration of radioactive metallic object. In one preferred embodiment, resonance frequencies fr, fr are measured with the EMAT, where where fr is a resonance frequency when a direction of an amplitude of a transverse ultrasonic wave generated by the EMAT is the same as the rolling direction of the metallic object of rolled material, and ft is a resonance frequency when a direction of the amplitude of the transverse ultrasonic wave is perpendicular to the rolling direction. A value R is calculated by using: R=(fr−ft)/{(fr+ft)/2}. The hydrogen concentration of the metallic object is calculated on the basis of the experimentally determined relation between the value R and hydrogen concentration.

Abstract: A high resolution biosensing system for detecting and identifying a biochemical material to be tested by using proportional relationship between frequency variation of oscillation and mass of the biochemical material to be tested comprises a biosensor: all oscillator for generating oscillation based on the sensed result, a phase-lock loop circuit receiving the oscillation of the oscillator and generating pulse signals; an ultra-high frequency counter for counting the Bulb; signals; and a microprocessor for storing and displaying output from the ultra-high frequency counter and for controlling the oscillator. The phase-lock loop circuit generates the pulse signals of a frequency, which is n times the frequency of the oscillator and with a constant phase difference therebetween to trigger the ultra-high frequency counter. Accordingly, the resolution can be raised up to n times.

Abstract: A method and device for determining concentration and rate of change of concentration of a gas having ability to act as crystal etchant, such as hydrofluoric acid (HF) or deuterium fluoric acid (DF) gas. A crystal 22 is placed in a chamber and subjected to erosion by the gas. The crystal resonant frequency, changeable during the crystal erosion, is determined and a crystal resonant frequency change is calculated to determine the concentration of the gas. The crystal 22 is preferably an AT-cut quartz crystal. The step of obtaining the crystal resonant frequency is preferably performed in a Colpitts oscillator. The step of calculating the gas concentration, proportional to the change in the crystal resonant frequency, may also encompass calculating a change and rate of change in the gas concentration, and averaging the calculated gas concentration. The crystal 22 is preferably inserted in a crystal holder 20, and mounted on an electronic box 34 which holds the oscillator board.

Abstract: An improved method of fluid analysis in the borehole of a well. A fluid sampling tool is fitted with a pumpout module that can be used to draw fluids from the formation, circulate them through the instrument, and then expel this fluid to the borehole. It has been determined that certain measurements would be most valuable to implement down hole, such as the formation fluid bubble point and dew point. Accurate bubble point and dew point measurements are made by forming bubbles or a liquid drop in a measured sample, and detecting same.

Abstract: The present invention provides a method of determining the boil states of a liquid as measured by an acoustic sensor which measures the acoustic signal generated by the liquid as it is heated. The acoustic signal is smoothed and a first derivative of the acoustic signal is calculated. Also the frequency of the acoustic signal is measured. Derivative inflection points, zero slope points, and acoustic signal frequencies are utilized to determine the pre-simmer, simmer, pre-boil, boil, boil dry, and boil over states of the liquid.

Abstract: By measuring two or more physical parameters of a thin sensing film which are altered when exposed to chemicals, more effective discrimination between chemicals can be achieved. In using more than one sensor, the sensors are preferably integrated on the same substrate so that they may measure the same thin film. Even more preferably, the sensors are provided orthogonal to one another so that they may measure the same portion of the thin film. These provisions reduce problems in discrimination arising from variations in thin films.

Abstract: The technology used in the present invention is acousto-ultrasonics (AU), in which a transmitted signal, at a controlled frequency is injected into a specimen with one transducer and received at another location by another transducer, permitting evaluation of the condition of the material in the signal path. In the experiments that were made using the present invention, the material within the press was a particleboard mat having the signal injected into the edge of one platen and received at the edge of the second platen. The AU signal received at the second platen is initially in response to pressure changes in the mat and subsequently follows the progression of internal bonding of the material. Since the propagated wave through the mat reacts to resin curing during the last phase of pressing, changes in material or press variables are reflected directly in shifts of the curve received at the second platen.

Abstract: Method and apparatus for monitoring curing in a resin. Acoustic, ultrasonic waves are propagated through a waveguide disposed through a quantity of resin while the resin is curing. The waves are transmitted and received by transducers arranged in an acousto-ultrasonic configuration with respect to a flexible waveguide. The waveguide may be made from bundled fibers. The velocity or amplitude of the acoustic waves is affected by the physical characteristics of the resin sample. Monitoring changes in the speed or amplitude of the propagated waves permits changes in the resin to be monitored in real time. Only a small sample quantity of resin need be employed.

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: Acoustic-wave sensor apparatus and method for analyzing a normally liquid petroleum-based composition for monitoring deposition-point temperature. The apparatus includes at least one acoustic-wave device such as SAW, QCM, FPM, TSM or APM type devices in contact with the petroleum-based composition for sensing or detecting the surface temperature at which deposition occurs and/or rate of deposition as a function of temperature by sensing an accompanying change in frequency, phase shift, damping voltage or damping current of an electrical oscillator to a known calibrated condition. The acoustic wave device is actively cooled to monitor the deposition of constituents such as paraffins by determining the point at which solids from the liquid composition begin to form on the acoustic wave device. The acoustic wave device can be heated to melt or boil off the deposits to reset the monitor and the process can be repeated.

Abstract: The cure state of a mass of a curable material, such as a composite material formed of a fiber embedded in a curable polymeric matrix, is measured. At least two wire segments are embedded into the mass, and an ultrasonic signal is propagated through the wire segments. From the ultrasonic propagation characteristics, the cure state of the mass is determined.

Abstract: The acoustic-wave sensor. The acoustic-wave sensor is designed for ambient or vapor-phase monitoring of a photoresist-stripping agent such as N-methylpyrrolidinone (NMP), ethoxyethylpropionate (EEP) or the like. The acoustic-wave sensor comprises an acoustic-wave device such as a surface-acoustic-wave (SAW) device, a flexural-plate-wave (FPW) device, an acoustic-plate-mode (APM) device, or a thickness-shear-mode (TSM) device (also termed a quartz crystal microbalance or QCM) having a sensing region on a surface thereof. The sensing region includes a sensing film for sorbing a quantity of the photoresist-stripping agent, thereby altering or shifting a frequency of oscillation of an acoustic wave propagating through the sensing region for indicating an ambient concentration of the agent. According to preferred embodiments of the invention, the acoustic-wave device is a SAW device; and the sensing film comprises poly(vinylacetate), poly(N-vinylpyrrolidinone), or poly(vinylphenol).

Abstract: An acoustic flame-out detection system that renders a large high pressure combustor 12 (FIG. 1) safe in the event of a flame-out and possible explosive reignition. A dynamic pressure transducer 22 is placed in the fuel line 16 and detects the stabilizing fuel pressure oscillations, caused by the combustion process. An electric circuit (FIG. 5) converts the signal from the combustion vortices, and transmitted to the fuel flow, to a series of pulses. A missing pulse detector 39 counts the pulses and continuously resets itself. If three consecutive pulses are missing, the circuit closes the fuel valve 20. With fuel denied, the combustor 12 is shut down or restarted under controlled conditions.

Abstract: A system and method for homogeneous bioassay uses acoustic energy emissions. A measurement cell is designed for binding reactions of mobile biorecognition molecules. The binding reaction contained in the measurement cell is for example a ligand/receptor binding reaction or a complementary nucleic acid binding reaction. A passive acoustic energy transducer is coupled to the measurement cell for detecting acoustic energy generated by the binding reaction of mobile biorecognition molecules. The passive acoustic energy transducer generates a corresponding analog electrical signal. A signal conditioner coupled to the passive acoustic energy transducer filters and amplifies the electrical signal. A signal analyzer determines spectra of the conditioned electrical signal corresponding to characteristic acoustic energy emissions of the binding reaction of mobile biorecognition molecules.

Abstract: A device for sensing a state change of a mechanical system, comprises at least one sound emitter (E), a receiver (R) as well as an electronic circuit (4) which allows to compare the received sound signal with reference values. The state of the mechanical system, such as the existence or the absence of contact among parts, is monitored by the processing of the signals corresponding to the emitted and received sound signals with the aim to allow to recognize the monitored state by the difference between the received signals and reference values. The sensing device may be used to monitor a number of variables such as contact, location, orientation, etc. of the mechanical parts by the same sensors there where traditionally different kinds of sensors were traditionally needed.

Abstract: The present invention provides a method and an apparatus for measuring the amount of unburned carbon in a sample of fly ash using infrared photoacoustic absorption. One preferred method according to the present invention involves directing modulated infrared radiation at a sample of fly ash and measuring the acoustic signal produced when the unburned carbon in the sample absorbs the radiation producing a thermal wave which propagates through the sample to generate a minute acoustic wave at interfaces between the carbon particles and gas surrounding the particles. One preferred apparatus includes a source of modulated infrared radiation, a chamber for containing the sample, a microphone to detect the acoustic signals, lock-in amplifier to separate the desired photoacoustic signal from noise at other frequencies, and a PC computer to provide output from the amplifier. This apparatus identifies the acoustic signal for determination of the amount of unburned carbon in the sample.

Abstract: A chemical sensor includes a piezoelectric support (1) capable of supporting a shear horizontal wave provided on its surface with an electrode (2,3). The sensor is characterized in that the surface of the piezoelectric support (1) including the region bearing the electrode (2,3) is covered by a layer of dielectric material (9) of thickness 0.5 to 20 microns. The piezoelectric support (1) is preferably a single crystal. The dielectric layer (1) may be of, for example, silicon dioxide or a suitable polymer, and preferably has a thickness of between 0.5 and 5 .mu.m.

Abstract: This invention relates to analyte-responsive compositions and analyte detection methods using these compositions, and, more particularly, to such compositions based on potassium titanyl phosphate (KTP) and analogs thereof and to analyte detection methods based on piezoelectric and optical properties of materials.

Abstract: A passive process for selectively sensing analyte molecules in a fluid by reflection of acoustic waves from a sensing surface of a bulk accoustive wave quartz sensing device to which analyte molecules bind is provided. The sensing surface has a plurality of receptors for which analyte molecules have an affinity. The process has the following steps:i) contacting a fluid in which analyte molecules are suspected with the sensing surface so that acoustic waves are reflected from the sensing surface;ii) directing acoustic waves at the sensing surface; andiii) detecting a change in a characteristic of acoustic waves reflected from the sensing surface due to analyte molecules binding the receptors. The change in a reflected acoustic wave characteristic being measured by electrical means detecting values which are related to the amplitude and phase of the reflected acoustic waves.

Abstract: The present invention is directed to methods and apparatus relating to an accelerometer electrical signal recorder and playback module. The recorder module may be manufactured in lightweight configuration and includes analog memory components to store data. Signal conditioning circuitry is incorporated into the module so that signals may be connected directly from the accelerometer to the recorder module. A battery pack may be included for powering both the module and the accelerometer. Timing circuitry is included to control the time duration within which data is recorded or played back so as to avoid overloading the analog memory components. Multiple accelerometer signal recordings may be taken simultaneously without analog to digital circuits, multiplexing circuitry or software to compensate for the effects of multiplexing the signals.

Abstract: An apparatus for processing electrical signals corresponding to acoustic emissions produced in a machine or process comprises a transducer acoustically coupled to the machine or process, which detects the acoustic emissions and converts them into an output signal. The output signal is amplified by an amplifier, rectified and enveloped by an enveloper having a short time constant to produce an electrical signal. An enveloper having a long time constant, measures the mean level of the electrical signal. A DC component remover removes the DC component from the electrical signal and an enveloper, having a long time constant, measures the mean level of the rectified AC component of the electrical signal. A processor having a low sampling rate, measures a power of the ratio between the mean level of the rectified AC component of the electrical signal and the mean level of the electrical signal.

Abstract: A method of identification and quantification of absorbed chemical species by measuring changes in both the velocity and the attenuation of an acoustic wave traveling through a thin film into which the chemical species is sorbed. The dual output response provides two independent sensor responses from a single sensing device thereby providing twice as much information as a single output sensor. This dual output technique and analysis allows a single sensor to provide both the concentration and the identity of a chemical species or permits the number of sensors required for mixtures to be reduced by a factor of two.

Abstract: An apparatus for the measurement of the cavitation or ebullition rate comprises an accelerometric transducer in contact with the liquid under cavitation or boiling and a filter and amplifier connected in cascade and having an input electrically connected to the transducer for providing on the output of the amplifier a signal containing information about cavitation or ebullition. This signal is then processed and displayed by two separate circuits. The first threshold circuit is connected to the output of the amplifier for eliminating signals having a value lower than a preset threshold value, a flash follower connected to the threshold circuit, and a counter and display connected to the flash follower. The display is adapted to provide a count of events in the signal sensed by the accelerometric transducer which surpass the preset threshold value. The second circuit includes an r.m.s. converter for providing the r.m.s. value of the signal obtained on the output of the amplifier.

Abstract: The present invention provides a method of detecting a void-related fault in a metal or metal alloy component. The method comprising filling the fault with a fluid, preferably liquid; treating the component and fluid so as to produce thermal-excitation in the component and fluid; and thereby cause a detectable acoustic signal. The detection of the signal detects the presence of a void-related fault. The invention also provides a method of locating and characterizing a void-related fault which comprises detection of the fault as described, measuring the parameters of the acoustic signal and the conditions for producing the signal, and correlating the parameters and conditions with the location and characteristics of the fault. The invention is particularly useful for the detection of microbiologically induced corrosion (MIC). The invention also concerns a method of evaluating a component for the severity of a void-related damage.

Abstract: Reference materials of differing indices of refraction or acoustic impedances are incorporated into liquid compositions to monitor the solidification process of these liquid compositions. Light or acoustic waves are used to indirectly measure the difference between the index of refraction or acoustic impedance of the solidfying composition and the reference material. The method provides an accurate in situ indication of the completion of the solidification process as well as a monitor of the degree of solidification during the solidification process.

Abstract: Reference materials of differing indices of refraction or acoustic impedances are incorporated into liquid compositions to monitor the solidification process of these liquid compositions. Light or acoustic waves are used to indirectly measure the difference between the index of refraction or acoustic impedance of the solidifying composition and the reference material. The method provides an accurate in situ indication of the completion of the solidification process as well as a monitor of the degree of solidifications during the solidification process.

Abstract: Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo technique, wherein an ultra-sonic pulse is emitted from a transducer at the ice-accreting surface of a structure, the pulse is reflected at the periphery of the accreted ice and the reflection is detected. The time delay is calibrated and related to ice thickness and accretion rate.

Abstract: A method and apparatus for checking a heterogeneous transformation process of diffusion kinetics taking in a turbulent flow of a liquid, whereby the real-time checking or control of the processes is possible. The method involves the steps of detecting acoustic vibrations caused by oscillations of bubbles present in the turbulent flow of liquid, producing an electric signal reflecting the spectral compostion of the detected signal, and forming therefrom a measure signal reflecting the relative instantaneous value of the turbulent diffusion coefficient of the flowing liquid. The apparatus comprises a series circuit including an acoustic sensing unit 1, an amplifier 2, signal processing means 3 and computing means 4, wherein the signal processing means 3 are equipped with a circuit for dividing the output signal of the amplifier 2 into spectral ranges and determining a characteristic value and the average value for each range and the ratio of the characteristic values.

Abstract: An ice detector of the vibrating element type comprises a tube that vibrates along its longitudinal axis, and is driven by an excitation coil at the natural frequency of the tube is sealed by a diaphragm which has a surface exposed to an air stream in which icing is to be sensed. The exposed diaphragm surface is deflectable during vibration of the tube at a flexible support portion of the diaphragm. As ice accumulates on the exposed surface of the flexible support the spring rate or flexibility of the flexible support changes, thereby changing the natural frequency of the vibration of the tube section. The changes in the natural frequency are sensed to determine that ice is accumulating. The diaphragm is of low mass, and small so that stiffness of small amounts of ice significantly changes the spring constant of the flexible support and the diaphragm is shaped to conform to adjacent aerodynamic surfaces.

Abstract: Disclosed is a method of monitoring physical and chemical changes in a host material which passes from a liquid state to a solid state. A waveguide is embedded in the host material while it is in the liquid or uncured state, the waveguide extending outside of the host material. A sound wave is sent through the waveguide and is monitored after it has passed through the host material. An article is also disclosed of a container having a liquid sealing exit means for waveguide, a waveguide which passes through the liquid sealing exit means into the container, a solidifiable liquid in the container at a level above the liquid sealing exit means, means outside the container for sending an acoustic wave through the waveguide into the container, and means outside the container for monitoring the acoustic wave after it has passed through said waveguide into the container.

Abstract: In a device for the determination of the vibrations occurring at the internals of a reactor pressure vessel, it is possible to perform the maintenance of the vibration detector located in a housing from outside the reactor pressure vessel. One end of a guide tube is fed through a pipe stub to a receptacle cone connected to the core internals. The end of the guide tube facing away from the reactor pressure vessel is cup-shaped and is sealed with a cover. A flexible rod is connected to the housing and its other end extends into the cup-shaped end of the guide tube. The flexible rod and with it the housing connected to it can be inserted into the receptacle cone, providing good transmission of the vibrations prevailing at the internals, which reach an evaluation unit through the cable.

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: A sensor for monitoring the deposition of frozen fog and/or ice on evaporator, refrigeration machine or heat pump surfaces, includes a can-shaped housing having opposite sides. A mounting heat conductingly connects the housing to the evaporator. First and second membranes are respectively disposed at the opposite sides of the housing, and first and second electro-acoustic transducers are each attached to a respective one of the membranes. An alternating voltage is applied to the first transducer causing the first transducer to oscillate the first membrane, and the second membrane is spaced from the first membrane by a distance permitting oscillation of the first membrane to oscillate the second membrane.

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: A method of testing new fuel rods for assemblies for nuclear reactors.Ultrasonic waves are transmitted in the canning tube of the fuel element disposed in the open, with an oblique incidence with respect to the axis of the tube, from one region of the side wall of the tube. By reflection at the walls of the canning tube, these waves produce plate waves or Lamb waves. These Lamb waves are picked up after a certain distance has been covered along the length of the canning tube and the attenuation undergone by these Lamb waves is measured. From this, by comparison with the attenuation results obtained at another part of the length of the tube or with a standard tube, data on the possible presence of moisture in the fuel rod is deduced. The invention particularly applies to the testing of fuel rods of assemblies for a pressurized water nuclear reactor.

Abstract: Method of and apparatus for the continuous measurement of changes in rheological properties of monomers during polymerization. Longitudinal ultrasonic oscillations are introduced into the polymerizing system, and oscillations received after passage through a part of the polymerization system are monitored as the polymerization process proceeds. The ultrasonic oscillations have a frequency of 0.02 to 100 MHz. The monitoring may be of the absorption of the oscillations and/or the rate of propagation of the oscillations.

Abstract: A process for determining the interactions between a solution and a body immersed in the solution, comprising the steps of measuring the sound emission from the body, such as sound waves in the ultrasonic range, while the solution and body are interacting and using this measurement to determine the interaction. The process can be used, inter alia, during the chemical removal of material from a body by a solution, such as chemical etching, to determine the degree of exhaustion of the solution. Moreover, the sound emission can be used in the control of further interaction between the solution and body.

Abstract: A method for detecting and locating defective fuel elements in a liquid cooled nuclear reactor employing a sonic/ultrasonic dual test. In accordance with the invention acoustic transducers, sensitive to a broad range of frequencies ranging from the audio to ultrasonic range, are respectively coupled to the exposed top end plugs of the fuel elements of a nuclear reactor fuel assembly. The respective fuel assemblies are voided of coolant, raising the temperature of the individual elements to a point that will boil any liquid coolant present in a defective fuel tube. The audio output of each transducer is translated into a graphic display identifying the presence and location of defective fuel elements. At prescribed intervals passive acoustic monitoring is interrupted for a pulse-echo attenuation measurement of each element. The respective transducers are sequentially energized, communicating pulsed acoustic energy along the fuel element cladding.

Abstract: An ultrasonic nondestructive system and method for monitoring resin cure during composite sheet material fabrication is described which comprises a first transducer for directing a plurality of ultrasonic pulses of preselected pulse frequency along a selected propagation axis onto a first surface of the material during the curing of the resin, a second transducer near the second surface of the material for receiving transmitted pulses and for providing output signals characteristic of the transmitted pulses, and electronic signal processor and display equipment responsive to signals from the second transducer for analyzing the signals and providing output corresponding to the amplitude and duration of the transmitted pulses.