Abstract: A system for determining the temperature of a supercritical fluid that involves determining the speed of sound in the supercritical fluid.

Abstract: An example microscope includes a pump laser for providing a first illumination to a sample. A laser array provides a second illumination to the sample. The laser array may include a plurality of laser elements, each providing oblique illuminations to the sample. An illumination collecting source collects the first illumination and the second illumination from the sample. The illumination collecting source may capture transient 3D refractive index (RI) variations in the sample due to the first illumination and second illumination.

Abstract: A method to measure the transient thermal diffusivity performance of a heat dissipation module by selecting two measurement points on the surface of the heat dissipation module, and locating the two measurement points at the same side of the thermal center point but different distances, and measuring the temperature of the two measurement points separately and using first equation which is the analytical solution of the energy equation. After calculating the first equation, second and third equations are used to find M. The distance X1 between M and the first measurement point and temperature T1 at a moment of transient state are also inserted into the first equation to obtain the value of the thermal diffusivity coefficient ?, which represents the transient thermal diffusivity performance for the heat dissipation module.

Abstract: A temperature state of one or more fluids in one or more enclosures is determined. Acoustic data is collected using a microphone. Frequency domain features are determined based on the acoustic data, where the frequency domain features are obtained across a frequency range of the acoustic data. The frequency domain features are correlated to the output of a machine learning acoustic analysis model and the one or more fluids are classified based on temperature based on the correlated one or more frequency domain features. In addition, the machine learning acoustic analysis model is trained by recording acoustic training data using a microphone and collecting temperature data for a fluid across a range of temperatures for the fluid. Frequency domain features are determined across a frequency range of the acoustic training data and the frequency domain features are correlated to the temperature data for a fluid.

Abstract: A hybrid integrated thermal sensor device includes a magnetic tunnel junction (MTJ) device electrically coupled in series with at least one CMOS transistor and disposed between a voltage rail terminal and a ground terminal. An output terminal is electrically coupled to a drain of the at least one CMOS transistor. The MTJ operates in an anti-parallel state and the output terminal provides a voltage indicative of a temperature of the MTJ device based on an MTJ antiparallel resistance. A distributed sensor network for real-time thermal mapping of an integrated circuit (IC) is also described.

Abstract: An apparatus and a method for monitoring the relative relationship between the wafer and the chuck is provided, especially for monitoring whether the wafer is sticky on the chuck when the wafer is de-chucked. The lift pins may be extended outside the chuck to separate the wafer and the chuck when the wafer is de-chucked. By detecting the capacitance between the de-chucked wafer and the chuck, especially by comparing the detected capacitance with the capacitance that the wafer is held by the chuck, one may determine whether the wafer is sticky on the chuck, or even whether the wafer is properly supported by the lift pins. Accordingly, an early alarm may be issued if the wafer is sticky or improperly removed. Besides, by controlling a switch electrically connected to a lift pin that contacted the wafer, the charges at the wafer may be eliminated.

Abstract: A method and system are provided with which it is possible to detect non-firing and untimely firing events in internal combustion and, if necessary, the temperature of the gas in the exhaust gas pipe. This is performed in general by measuring the speed of sound and determining the phase angle between the sender and receiver either arranged on different sides of the exhaust gas pipe or on the same side of the exhaust gas pipe. The receiver, depending on the measurement principle, can include one, two, or in special applications three receivers. Additionally, if necessary, it is possible to suppress the structure-borne sound influence on a speed of sound measurement with low cost and high stability.

Abstract: A biosensor includes a detection element having an analyte detecting portion which is monotonically increased in mass in response to detection of an analyte; a reference element having a reference measuring portion which exhibits no reactivity to the analyte; a mixer which mixes a detection signal responsive to mass variations in the analyte detecting portion from the detection element and a reference signal from the reference element; a measurement portion which calculates two candidate phase-change values of a positive value and a negative value, from a signal mixed by the mixer in accordance with a heterodyne system, and determines a phase-change value from the two candidate phase change value by judging whether the phase is positive or negative based on temporal changes in signal strength; and a detection amount calculation portion which calculates a detection amount of the analyte based on the phase change value determined by the measurement portion.

Abstract: Provided herewith is a thermometer that calculates an average temperature between a starting point and a target surface. Also provided is a method of calculating an average temperature in an open space, between a starting point and a target surface. In additional embodiments, a method of calculating a two dimensional average temperature gradient in an open space is provided. Further provided is a method of calculating a three dimensional average temperature gradient in an open space.

Abstract: A chemical mechanical polishing apparatus includes a platen to support a polishing pad, and an in-situ acoustic emission monitoring system including an acoustic emission sensor supported by the platen, a waveguide configured to extending through at least a portion of the polishing pad, and a processor to receive a signal from the acoustic emission sensor. The in-situ acoustic emission monitoring system is configured to detect acoustic events caused by deformation of the substrate and transmitted through the waveguide, and the processor is configured to determine a polishing endpoint based on the signal.

Abstract: Systems and methods for measuring phase dynamics and other properties (e.g. intracranial pressure) are disclosed. For example, the system may generate a reference waveform and a measurement waveform using digital synthesizers, each waveform having an identical constant frequency but also a relative phase shift. Next, system may send a tone-burst, via a transducer, into a sample (e.g. a skull or a bonded material), and then receive a reflected tone-burst in response. Then, a phase difference between the received tone-burst and the measurement waveform may be determined with a linear phase detector. Next, the phase shift of the measurement waveform may be adjusted, by the determined phase difference, such that there is no longer any phase difference between the received tone-burst and the adjusted measurement waveform generated by the appropriate digital synthesizer. A similar adjustment may occur after subsequent tone-bursts, allowing accurate monitoring of continuously variable phase relationships.

Abstract: An environmental parameter sensor for a mobile device is described comprising a first acoustic transducer; a second acoustic transducer arranged at a predetermined distance from the first acoustic transducer; a controller coupled to the first acoustic transducer and the second acoustic transducer; wherein the controller is configured to determine at least one of a time-of-flight value and an attenuation value of an acoustic signal between the first acoustic transducer and the second acoustic transducer and to determine at least one environmental parameter from the at least one of the time-of-flight value and the attenuation value The environmental parameter sensor may determine environmental parameters such as temperature, wind speed, and humidity from acoustic measurements.

Abstract: Disclosed is a method and apparatus for measuring semiconductor substrate temperature using a differential acoustic time of flight measurement technique. The measurement is based on measuring the time of flight of acoustic (ultrasonic) waves across the substrate, and calculating a substrate temperature from the measured time of flight and the known temperature dependence of the speed of sound for the substrate material. The differential acoustic time of flight method eliminates most sources of interference and error, for example due to varying coupling between an ultrasonic transducer and the substrate. To further increase the accuracy of the differential acoustic time of flight measurement, a correlation waveform processing algorithm is utilized to obtain a differential acoustic time of flight measurement from two measured ultrasonic waveforms. To facilitate signal recognition and processing, a symmetric Lamb mode may be used as mode of excitation of the substrate.

Abstract: The disclosure relates to a method for determining a temperature in a pressurized flow path of a gas turbine comprising the steps of sending an acoustic signal from an acoustic signal emitting transducer across a section of the pressurized flow path, detecting the acoustic signal with a receiving transducer, measuring the time needed by the acoustic signal to travel from the acoustic signal emitting transducer to the receiving transducer, calculating the speed of sound, and calculating the temperature as a function of the speed of sound, the heat capacity ratio (?) and a specific gas constant (Rspec) of the gas flowing in the pressurized flow path. Besides the method, a gas turbine with a processor and transducers arranged to carry out such a method is disclosed.

Abstract: Provided a sound velocity correction device including an environmental parameter obtainer that acquires a measured value of a surrounding environmental parameter of a sound collector that collects a sound emitted from a sound source; and a sound velocity corrector that corrects a sound velocity of the sound which is used to form directivity in a directing direction toward the sound source from the sound collector, using the measured value of the surrounding environmental parameter of the sound collector which is acquired by the environmental parameter obtainer.

Abstract: The present invention relates to system for measuring pressure and temperature based on change in the characteristic properties of a medium for ultrasound under the effect of pressure and temperature. The invention is based on two waveguides where geometry is adapted to the medium's characteristic properties for ultrasound such that only planar pressure waves are generated in the waveguides. The first of the waveguides is arranged for measuring temperature due to thermal expansion of the medium, where the medium is pressure-compensated by means of an internal compensator to prevent thermal pressure accumulation, and where measuring temperature is based on the medium's specific known characteristic data for ultrasound under the effect of temperature under constant pressure.

Abstract: The invention is a. firearm (1) comprising a verification device (10) suitable for verifying and detecting an anomaly of the state of the barrel (2), such as the presence of partial or total occlusions or variations of cross-section. The device (10) comprises receiver means (200), on the firearm (1), suitable for detecting a detected signal (R) derivable from an emitted signal (E), influenced by said anomaly.

Abstract: A system, method and apparatus for controlling a downhole operation is disclosed. A tool is operated to perform the downhole operation at a selected downhole location using a first value of an operation parameter of the tool. A magnetostrictive probe is used to determine a temperature profile along a section of a wellbore related to the operation being performed using the first value of the operation parameter. At least one temperature of the temperature profile is compared to a selected threshold. The operation parameter is altered to a second value based on the comparison of the temperature profile to the selected threshold.

Abstract: A fluid flow system, device, and method for locating a fluid layer in a fluid flow using an acoustic waveguide. The acoustic waveguide comprises a waveguide base segment, and a waveguide reflector segment. The waveguide reflector segment comprises a plurality of disc shaped waveguide reflectors along its length for locating a fluid layer.

Abstract: An ultrasonic thermometer for measuring a temperature profile along a measurement axis of a structure, comprising a continuous measurement pathway of a structure (310) having a longitudinal measurement axis and proximal (202) and distal ends (204), and at least two backscatterers (332) formed therein transverse to the longitudinal axis and separated by a predetermined separation distance.

Abstract: Disclosed is a method and apparatus for measuring semiconductor substrate temperature using a differential acoustic time of flight measurement technique. The measurement is based on measuring the time of flight of acoustic (ultrasonic) waves across the substrate, and calculating a substrate temperature from the measured time of flight and the known temperature dependence of the speed of sound for the substrate material. The differential acoustic time of flight method eliminates most sources of interference and error, for example due to varying coupling between an ultrasonic transducer and the substrate. To further increase the accuracy of the differential acoustic time of flight measurement, a correlation waveform processing algorithm is utilized to obtain a differential acoustic time of flight measurement from two measured ultrasonic waveforms. To facilitate signal recognition and processing, a symmetric Lamb mode may be used as mode of excitation of the substrate.

Abstract: A method and apparatus for operating a gas turbine engine including determining a temperature of a working gas at a predetermined axial location within the engine. An acoustic signal is encoded with a distinct signature defined by a set of predetermined frequencies transmitted as a non-broadband signal. Acoustic signals are transmitted from an acoustic transmitter located at a predetermined axial location along the flow path of the gas turbine engine. A received signal is compared to one or more transmitted signals to identify a similarity of the received signal to a transmitted signal to identify a transmission time for the received signal. A time-of-flight is determined for the signal and the time-of-flight for the signal is processed to determine a temperature in a region of the predetermined axial location.

Abstract: A method and apparatus for heat quantity measurement, wherein, with an ultrasonic, flow measuring device, which works according to the travel time difference principle, the flow of a fluid of known chemical composition through the lumen of a pipeline is ascertained, and wherein the temperature of the fluid before and after a heat transferer is ascertained, wherein, for a first ascertaining of the temperature of the fluid, the velocity of sound in the fluid is ascertained with the ultrasonic, flow measuring device and a temperature is ascertained outside of the lumen of the pipeline.

Abstract: An ultrasonic thermometer for measuring a temperature profile along a measurement axis of a solid structure, comprising a continuous measurement pathway of a solid structure (310) having a longitudinal measurement axis and proximal (202) and distal ends (204), and at least two backscatterers (332) formed therein transverse to the longitudinal axis and separated by a predetermined separation distance.

Abstract: A condition measurement apparatus is provided and includes a gas turbine engine combustor having an end cover, a liner defining a liner interior and a fuel nozzle communicative with the liner interior, the end cover being formed to separate a cold side thereof, which is a relatively low temperature environment, from a hot side thereof, which is a relatively high temperature environment in which the liner and the fuel nozzle are disposed, the combustor being formed to define a fuel flow path extending through piping disposed at the cold side of the end cover by which fuel is deliverable to the fuel nozzle, and a condition sensing device operably mounted on the piping.

Abstract: An aerodynamically shaped profile member for aircraft and wind power stations includes, for example, phased-array ultrasonic generator arrangement arranged therein. During operation of the profile member, the ultrasonic generator emits ultrasonic waves in a targeted manner in multiple directions to determine a profile of the thickness of an ice layer on the surface of the aerodynamic profile. The structure may be, for example, a composite fiber material arranged around a foam core, with the ultrasonic generator arrangement being laminated into the composite fiber material. For measurement of the ice thickness, ultrasonic waves are transmitted in a targeted manner to different positions of the surface of the aerodynamic profile, and the ultrasonic waves reflected on the interfaces of the ice layer are detected. At least one region of the surface is scanned by means of the targeted ultrasonic waves, to determine an ice thickness profile.

Abstract: A method for performing ultrasonic testing comprising, in one embodiment, the steps of firing an ultrasonic transducer to generate an ultrasonic pulse that passes through a delay line, measuring a delay echo time of flight, and determining the temperature of the delay line using the delay echo time of flight, thereby eliminating the need for additional temperature measuring devices. Other embodiments further comprise the step of using the temperature of the delay line to determine the temperature of a test object, and using the temperature of the test object to determine a thickness of the test object that is compensated for thermal expansion and temperature dependent ultrasonic velocity.

Abstract: A temperature estimation method including: receiving a scan signal generated by scanning the target region using the ultrasound signal, and estimating, based on the scan signal, an echo shift which is an amount of change in time required for the ultrasound signal to pass through the target region, the time changing depending on the temperature in the target region; estimating, based on the estimated echo shift, a strain which is an apparent change rate of a travel distance required for the ultrasound signal to pass through the target region, the travel distance changing depending on the temperature in the target region; estimating, based on the estimated strain, a strain rate which is a temporal change rate of the strain; and estimating the temperature in the target region corresponding to the strain and the strain rate, based on a predetermined relationship between a strain, a strain rate, and a temperature.

Abstract: A method and apparatus for operating a gas turbine engine including determining a temperature of a working gas at a predetermined axial location within the engine. Acoustic signals are transmitted from a plurality of acoustic transmitters and are received at a plurality of acoustic receivers. Each acoustic signal defines a distinct line-of-sound path from one of the acoustic transmitters to an acoustic receiver corresponding to the line-of-sound path. A time-of-flight is determined for each of the signals traveling along the line-of-sound paths, and the time-of-flight for each of the signals is processed to determine a temperature in a region of the predetermined axial location.

Abstract: Methods of performing ultrasonic testing are disclosed, comprising the step of determining a temperature gradient of an ultrasonic wedge. In one embodiment of the invention, the method further comprises the steps of determining a sound velocity gradient of the ultrasonic wedge to determine the time it takes for sound waves emanating from a plurality of ultrasonic transducer elements attached to the ultrasonic wedge to reach a point of interest within a test object, and firing each of the ultrasonic transducer elements in a timed sequence based on the times such that sound waves from each of the ultrasonic transducer elements reach the point of interest at the same time. In other embodiments of the invention, the total attenuation and acoustic impedance of a sound wave traveling through the ultrasonic wedge is determined to adjust the amplitude of the sound wave such that the sound wave has sufficient amplitude to perform the ultrasonic testing.

Abstract: In one embodiment, an integrated circuit for providing distributed temperature sensing is disclosed. For example, the integrated circuit comprises a plurality of circuit components, an internal temperature sensing device deployed among the plurality of circuit components; and a plurality of ring-oscillators deployed among the plurality of circuit components, wherein at least one of the plurality of ring-oscillators is deployed adjacent to the internal temperature sensing device, where the plurality of ring-oscillators is used to provide one or more temperature measurements, e.g., a temperature gradient, for the integrated circuit.

Abstract: Ultrasound data are collected from a thermal source and a mass of tissue before initiating therapy to measure two parameters of the bio-heat transfer equation (BHTE). The parameters are the thermal diffusivity (K) of the tissue and the magnitude of the thermal source (Q). Once the parameters have been obtained, the BHTE can be calibrated to the specific mass of tissue and the specific thermal source. The calibrated BHTE can be used to generate a temperature dependence curve calibrated to the thermal source and tissue, and spatio-temporal temperature maps, to facilitate pre-therapy planning. During therapy, ultrasound data are collected to determine if Q changes during therapy, and if so, the BHTE is recalibrated using the new Q value, increasing an accuracy of the temperature estimations.

Abstract: A thermometer and extensometer for cables and conductors is described. The travel time of one or more acoustic signals along a conductor is used to determine the temperature along the conductor and the length of the conductor. The acoustic frequency is selected to minimize temporal dispersion of the propagating acoustic energy. The technique can be used to measure the temperature of the windings in a transformer or other electrical apparatus.

Abstract: A thermometer and extensometer for cables and conductors is described. The travel time of one or more acoustic signals along a conductor is used to determine the temperature along the conductor and the length of the conductor. The acoustic frequency is selected to minimize temporal dispersion of the propagating acoustic energy. The technique can be used to measure the temperature of the conductor in a buried, undersea or submerged electrical power cable.

Abstract: At least one transceiver sends ultrasonic pulses through an object, which at least partially transmits ultrasonic pulses, into an element which reflects the ultrasonic pulses. The ultrasonic pulse(s) can be reflected in a temperature-correlated manner from the reflective element to the transceiver.

Abstract: Apparatus, methods, and articles of manufacture for monitoring a condition of a material are disclosed. In particular, the example apparatus, methods, and articles of manufacture emit a first acoustic signal into a wall of the tubular member having a first temperature value and obtain a first propagation time associated with the first acoustic signal. In addition, a second acoustic signal is emitted into the wall having a second temperature value and a second propagation time associated with the second ultrasonic acoustic signal is obtained. The second temperature value is determined based on the first temperature value and the first and second propagation times.

Abstract: A method for determining the temperature of an away-facing surface of an object, wherein at least one ultrasonic pulse is transmitted through a surface of the object facing a transmitter/receiver unit into said object; the at least one ultrasonic pulse is reflected at least partially in the direction of the transmitter/receiver unit on the surface of the object facing away from the transmitter/receiver unit; and the reflected part of the at least one transmitted ultrasonic pulse is received by the transmitter/receiver unit. At least one temperature value for the object surface facing the transmitter/receiver unit is also determined; at least one value is determined for the propagation time of the at least one ultrasonic pulse through the object, and at least one temperature value for the object surface facing away from the transmitter/receiver unit is determined by the at least one temperature value for the object surface facing the transmitter/receiver unit and the at least one propagation time value.

Abstract: A condition or detecting a change in the condition of an optical element of a laser arrangement is detected. An ultrasonic signal is coupled into an optical element such that the ultrasonic signal travels along a path within the optical element, and a transit time or a change in transit time for the ultrasonic signal to travel along the path within the optical element is detected.

Abstract: A method for the measurement of the temperature of a plastified plastic material at the exit of an extruder, characterised in that the function of the sound, velocity in dependence of the temperature is measured and memorised for at least one plastified plastic material, the sound velocity is measured during the extrusion of the plastic material, and the respective temperature is determined from the velocity measurement values and the function.

Abstract: Methods of performing ultrasonic testing are disclosed, comprising the step of determining a temperature gradient of an ultrasonic wedge. In one embodiment of the invention, the method further comprises the steps of determining a sound velocity gradient of the ultrasonic wedge to determine the time it takes for sound waves emanating from a plurality of ultrasonic transducer elements attached to the ultrasonic wedge to reach a point of interest within a test object, and firing each of the ultrasonic transducer elements in a timed sequence based on the times such that sound waves from each of the ultrasonic transducer elements reach the point of interest at the same time. In other embodiments of the invention, the total attenuation and acoustic impedance of a sound wave traveling through the ultrasonic wedge is determined to adjust the amplitude of the sound wave such that the sound wave has sufficient amplitude to perform the ultrasonic testing.

Abstract: A thermometer and extensometer for cables and conductors is described. The travel time of one or more acoustic signals along a conductor is used to determine the temperature along the conductor and the length of the conductor. The acoustic frequency is selected to minimize temporal dispersion of the propagating acoustic energy. The technique can be used to measure the temperature of the windings in a transformer or other electrical apparatus.

Abstract: A thermometer and extensometer for cables and conductors is described. The travel time of one or more acoustic signals along a conductor is used to determine the temperature along the conductor and the length of the conductor. The acoustic frequency is selected to minimize temporal dispersion of the propagating acoustic energy. The technique can be used to measure the temperature of the conductor in a buried, undersea or submerged electrical power cable.

Abstract: An object of the present invention is to provide a piezoelectric resonator provided with a electrode on the surface of a plate piezoelectric blank, which excites the piezoelectric blank, the piezoelectric resonator being capable of suppressing deterioration of an electrode under high temperature circumstances. Another object is to provide a temperature sensor suitable for temperature measurement at high temperatures. As a concrete means for solving the problems is that the electrode includes a first metal layer, formed on the surface of the piezoelectric blank, and made of at least one kind selected from the group consisting of chromium (Cr), titanium (Ti), nickel (Ni), aluminum (Al) and copper (Cu), or having the same adhesion to the above-described piezoelectric blank as that of these metals; a second metal layer made of gold (Au) or silver (Ag) deposited on the surface of the first metal layer; and a third metal layer made of chromium (Cr) deposited on the surface of the second metal layer.

Abstract: A thermometer and extensometer for cables and conductors is described. The travel time of one or more acoustic signals along a conductor is used to determine the temperature along the conductor and the length of the conductor. The acoustic frequency is selected to minimize temporal dispersion of the propagating acoustic energy. The technique can be used to measure the temperature and sag of an overhead power line, the temperature of the windings in a transformer, or the temperature of the central conductor in a coaxial power cable.

Abstract: The field of the invention is that of surface acoustic wave transponders and associated devices. This invention applies more particularly to the techniques for identifying and locating transponders. It also applies to the transmission of information or measurements, the transponder then being used as a transducer. This type of transponder can, in particular, be used on vehicles, and in particular on road vehicles. The inventive transponder (1) comprises a surface acoustic wave device, comprising one or more electronic filters (101) with narrow spectral band centered on one or more central frequencies and a delay line (102) operating in reflection mode. By having narrowband filters centered on different frequencies, it is thus possible to easily discriminate between different transponders. The delay lines make it possible to simply separate the transmitted signal and the received signal. The inventive transponder can also be used as a transducer.

Abstract: Ultrasound transducer temperatures are measured in response to a temperature dependent property of the ultrasound transducer. The temperature is measured without addition of new electronics or hardware retrofits of the transducer. By implementing software and/or hardware on the ultrasound system rather than the transducer, the temperature is measured in order to provide a level of fault protection. The upgraded or new ultrasound system uses either old or new transducers while still providing temperature measurement. For example, the temperature of the lens or window is measured as a function of changes in attenuation or acoustic velocity. The receive beamformer already implemented on many ultrasound systems is used to measure a temperature dependent property of the lens or window. As another example, the dielectric constant or capacitance of one or more transducer elements is measured using additional hardware in the ultrasound system.

Abstract: Apparatus, methods, and articles of manufacture for monitoring a condition of a cavity surface of an elongated member having a cavity therein. In particular, the example apparatus, methods, and articles of manufacture emit a first ultrasonic signal that propagates from a first surface of an elongated member having a cavity therein toward a second surface of the cavity having a first temperature value. First and second echoes associated with the first ultrasonic signal are then obtained. At least one of the first and second echoes is associated with a recess in the second surface. A condition of the second surface is monitored by determining a second temperature value of the second surface based on the first and second echoes and the first temperature value.

Abstract: The invention relates to a device (31) which comprises at least one piezoacoustic resonator element (2) having a piezoelectric layer (32) and two electrodes that are electrically contacted to the piezoelectric layer (32). The piezoacoustic resonator element (2) is configured in such a manner that, when a voltage is applied to the piezoelectric layer (32), a thickness oscillation of the piezoelectric layer (32) is excited via the electrodes with a resonant frequency. The inventive device is characterized by comprising, integrated into the piezoacoustic resonator element (2), a temperature measurement device (3) having a measuring element (37) that is configured as a thin layer.

Abstract: A technology is disclosed for holding the test subject contact surface temperature below a predetermined value without providing a temperature sensor or setting ultrasonic wave output excessively low and, according to this technology, reflex time t1, which passes through oil 6, is reflected by the inner surface of window 5, and is returned via oil, and reflex time t2, which passes through the window, is reflected by the outer surface of the window, and returned via window or oil, are detected, sound velocity of window=(thickness of window×2)/(t2?t1) is measured, and the surface temperature of the window is detected from this measured sound velocity.

Abstract: An acoustic pyrometer measures the average gas temperature across a space of known distance, especially turbulent, high temperature gas loaded with caustic particulates. It includes an acoustic signal generator that generates a high amplitude acoustic signal with a short rise time The acoustic signal generator includes an outer tank closed at top and bottom ends by top and bottom end walls and enclosing an outer chamber. A cylinder is supported within the tank and has top and bottom opposed ends. A mid-plate extends across the cylinder and defines the bottom end, and an axial opening in the mid-plate receives a shaft of a piston assembly having an upper piston and a lower piston at ends of the shaft. A throat is attached to the bottom end, and receives the lower piston. The lower piston seals the throat when received in the throat. The upper piston is slidable in the cylinder under influence of air pressure.