540 results about "Thermoacoustics" patented technology

A method and system for examining biological tissue includes the steps of radiating a tissue region with a plurality of microwave radiation pulses. The microwave pulses are swept across a range of microwave frequencies. In response to the swept frequency microwave pulses, the tissue region emits a plurality of thermoacoustic signals. At least one image of the tissue region is formed from the plurality of thermoacoustic signals. The signals can be ultrawideband signals.

A method and system for examining biological tissue includes the steps of radiating a tissue region with a plurality of microwave radiation pulses. The microwave pulses are swept across a range of microwave frequencies. In response to the swept frequency microwave pulses, the tissue region emits a plurality of thermoacoustic signals. At least one image of the tissue region is formed from the plurality of thermoacoustic signals. The signals can be ultrawideband signals.

A thermoacoustic generator includes a housing with a thermoacoustic core supported in the housing. The core is operable to introduce acoustical power into the housing to thereby oscillate the pressure of the gas in the housing at a frequency. A piezoelectric alternator is also supported in the housing and has a face that is movable when acted on by the acoustical power. The alternator includes a portion of piezoelectric material operable to produce electrical power when acted upon by a stress. The piezoelectric material is in mechanical communication with the movable face so that movement of the face stresses the piezoelectric material. The alternator has a moving mass that serves as a substantial portion of the resonating mass inside the housing, thereby providing a pressure oscillation frequency in the housing substantially lower than for a similar system with a rigid member replacing the alternator.

The present disclosure details a thermoacoustic driven compressor having a pressurized housing, which contains within a thermoacoustic engine and a working gas, coupled to a positive displacement reciprocating compressor. The thermoacoustic driven compressor generates scalable compressed air from a given heat source.

A thermoacoustic refrigerator having a relatively small size which utilizes one or more piezoelectric drivers to generate high frequency sound within a resonator at a frequency of between about 4000 Hz and ultrasonic frequencies. The interaction of the high frequency sound with one or more stacks create a temperature gradient across the stack which is conducted through a pair of heat exchangers located on opposite sides of each stack. The stack is comprised of an open-celled material that allows axial, radial, and azimuthal resonance modes of the resonator within the stack resulting in enhanced cooling power of the thermoacoustic refrigerator.

A thermoacoustic cooling system for cooling an object such as a microelectronic chip. Heat produced by the object is transferred to a thermoacoustic engine. The thermoacoustic engine may include a resonator defining a chamber. A stack may be positioned in the chamber with one side of the stack adjacent to the heat source, and the opposite side of the stack adjacent to air in the chamber having a relatively cooler temperature. One or more orifices may be formed in the resonator such that the acoustic power generated by the thermoacoustic engine creates a synthetic jet to circulate air and move the air away from the object being cooled. Thus, the heat produced by the object is used to power the thermoacoustic engine to thereby remove heat from the object. The thermoacoustic engine may use no moving parts and may require no external power source other than the object being cooled.

A sound wave generator that includes a carbon nanotube structure. The carbon nanotube structure produces sound by means of the thermoacoustic effect.

A method for controlling a temperature distribution within a combustor having a plurality of chamber sections comprising controlling a fuel-to-air ratio in the chamber sections. At least two chamber sections have different fuel-to-air ratios to create a non-uniform temperature distribution within the combustor to reduce thermoacoustic instabilities.

In one aspect, the present invention provides nano-scale heaters, such as nano-scale thermoacoustic loudspeakers comprising suspended metal nanobridges prepared using atomic layer deposition (ALD). The loudspeakers of the invention are capable of producing audible sound when stimulated with an electrical current or other energetic stimulus. In another aspect, the present invention provides methods of preparing and using such nanodevices.

The invention discloses a thermoacoustically-driven thermally-coupled two-stage pulse tube cooling system, which comprises a U-shaped double side-drive thermoacoustic engine, connecting pipes and a thermally-coupled two-stage pulse tube cooler, which are connected sequentially. The system is characterized in that: a U-shaped resonating tube connects two thermoacoustic cores; acoustic power flows flow out from the directions of a cold end and a hot end of a thermoacoustic plate stack to drive an acoustic oscillator and the pulse tube cooler in the U-shaped resonating tube respectively; the backward pressure waves output by the two thermoacoustic cores drive the two stages of the thermally-coupled two-stage pulse tube cooler through the connecting pipes respectively, the pulse tube cooler is connected to the pressureantinode positions on the two ends of the thermoacoustic engine, and a larger output pressure ratio is favorable for the acquisition of optimal lower cooling performance of the pulse tube cooler; the operation method of combining the thermoacoustic plate stack and a thermoacoustic regenerator is adopted to improve the acoustic power output capacity and the vehicle efficiency; and a liquid piston is introduced into the U-shaped resonating tube to form a gas-liquid coupled oscillation system so as to reduce resonance frequency and increase pressure ratio and consequentially improve the performance of the driven pulse tube cooler.

A MEMS based thermoacoustic cryo-cooler for thermal management of cryogenic electronic devices. The cryogenic cooling system can be integrated directly into a cryogenic electronic device. A vertical comb-drive provides an acoustic source through a driving plate to a resonant tube. By exciting a standing wave within the resonant tube, a temperature difference develops across a stack in the tube, thereby enabling heat exchange between heat exchangers. A tapered resonant tube improves the efficiency of the cooling system, compared with a simple cylinder configuration, leading to reduced harmonics and strong standing waves.

The invention relates to an acoustic resonance type thermally-driven travelling wave thermo-acoustic refrigerating system. The acoustic resonance type thermally-driven travelling wave thermo-acoustic refrigerating system is composed of N elastic films and N thermo-acoustic units, wherein the thermo-acoustic units are connected end to end through resonance tubes and form an annular loop, N is a positive integer ranging from 3 to 10, and the phase difference of volume flow rates of the two ends of each thermo-acoustic unit is 360 degrees / N. Each thermo-acoustic unit is composed of a thermo-acoustic engine and a pulse tube refrigeration machine. No movable parts are arranged in the refrigerating system, and reliability of the refrigerating system is further improved. Pure travelling wave phase positions can be obtained in an acoustic resonance loop system, acoustic power flowing out of each thermo-acoustic unit through the corresponding pulse tube refrigeration machine is recycled by the next thermo-acoustic unit, and therefore work efficiency of the system can be further improved. In addition, different numbers of thermo-acoustic units can be connected in series according to the required cooling capacity condition so that large-cooling-capacity output can be achieved. The acoustic resonance type thermally-driven travelling wave thermo-acoustic refrigerating system is large in cooling capacity, high in efficiency, long in service life and simple in structure, and has good application prospects in places where the requirements for cooling capacity are high.

Thermoacoustic sensors, such as dynamic pressure sensors, in the combustor measure vibratory responses of the combustor. An integrated monitoring and control system controller correlates sensor readings with combustion thermoacoustic properties in order to identify combustion anomalies by wavelet or Fourier analysis techniques; determine bulk temperature characteristics within the combustor with dominant mode frequency analysis techniques; and optionally determines absolute active path temperatures within the combustor with acoustic pyrometry transmission and time-of-flight analysis techniques. In some embodiments all of the monitoring functions are performed with a commonly shared array of thermoacoustic sensors that function as both combustion dynamics thermoacoustic vibration / wave receivers and acoustic transmitters. The monitored combustion properties are used for controlling gas turbine combustion.

A laser induced thermo-acoustical system has a waveguide for propagating laser radiation to an absorbing layer of a tip. The tip has an absorbing layer serving to absorb the laser radiation propagating through the waveguide. The absorbing layer has such an absorption coefficient that upon absorbing the laser radiation the absorbing layer heats up to boil a quantity of a liquid when the tip is surrounded by the liquid. A laser induced thermo-acoustical method calls for providing a waveguide for propagating laser radiation to the absorbing layer of the tip to be at least partially absorbed by the absorbing layer and to boil a quantity of the liquid surrounding the tip and generating the stream of liquid. The laser induced thermo-acoustical streaming of the liquid is used, in particular, for the treatment of a root canal and periodontal pockets.

Active acoustic pyrometry-based gas flow temperature measurement, such as for monitoring of gas turbine combustors, including industrial gas turbine (IGT) combustors is incorporated into the combustion monitoring and control system by addition of an acoustic transmitter or acoustic transceiver that transmits a sound wave in a line-of-sight with a plurality of acoustic sensors, such as dynamic pressure sensors. For temperature measurement, in some embodiments sound transmission time-of-flight that is directed generally transverse the gas flow path is measured by the controller and correlated with gas flow temperature along the line-of-sight. In other embodiments line-of-sight correlated gas flow temperatures in up and down stream planar paths are interpolated. In an integrated thermoacoustic pressure-based sensor and monitoring / control system embodiment, the controller determines absolute active path temperatures with acoustic transmission and time-of-flight analysis techniques.

A method for controlling a temperature distribution within a combustor having a plurality of chamber sections comprising controlling a fuel-to-air ratio in the chamber sections. At least two chamber sections have different fuel-to-air ratios to create a non-uniform temperature distribution within the combustor to reduce thermoacoustic instabilities.

The invention relates to a thermoacoustic engine for outputting rotary power, which comprises a hot-end heat exchanger, a sheet packing or heat regenerator, a cold-end heat exchanger and a resonant tube; and the thermoacoustic engine is characterized by also comprising a self-rectifying air turbine device which is used for converting the alternating flow of oscillating current into rotary motion and is positioned in the resonant tube. Aiming at the problems of large abrasion, low efficiency, short service life and no adjustability of the motion displacement of a piston caused by adopting the piston to push a crank connecting rod mechanism in the prior method for converting reciprocating and alternating oscillating current into the rotary motion and outputting power , the thermoacoustic engine for outputting the rotary power provided can realize the conversion of the reciprocating and alternating oscillating current generated by the thermoacoustic engine into the rotary motion, outputs power to drive load and has the characteristics of small abrasion, high efficiency, long service life and good controllability.

The invention discloses an ultrashort pulse microwave thermoacoustic imaging method and an ultrashort pulse microwave thermoacoustic imaging device. The device comprises an ultrashort pulse microwave generator, an ultrasonic detector and a data acquisition and image reconstruction device. The method comprises the following steps of: fixing an object to be detected in a coupling tank containing deionized water; making the ultrashort pulse microwave generator output ultrashort pulse microwaves under the control of a trigger circuit, making the ultrashort pulse microwaves uniformly irradiate theobject to be detected through a pulse transmitting antenna, and exciting to obtain thermoacoustic signals; and receiving the thermoacoustic signals by using the ultrasonic detector, making signals output by the trigger circuit trigger a data acquisition card to acquire the thermoacoustic signals, and recording and saving the thermoacoustic signals and reconstructing images by using a computer. The ultrashort pulse microwave generator with ns-level pulse width excites the thermoacoustic signals, the thermoacoustic signal exciting efficiency can be greatly improved, and a sample to be detected is subjected to high-resolution tomography. The device has high imaging resolution, simple structure and low cost, and is convenient to operate and easily promoted and applied in the field of nondestructive testing.

The invention discloses a fluctuation thermoacoustic generation system, which comprises the following loop parts in sequence: cold junction heat exchanger, heat regenerator, heater, heat buffer pipe, hot junction heat exchanger, ring-shaped connection pipe and line generator in the pipe, wherein the generator contains a cylinder with one end of casing on the pipe and the other end with line sliding bearing; a double-loop magnetic-inductive soft iron with ring orifice is set in the cavity between cylinder and casing; the permanent magnet is inserted in the outer ring magnetic wall of soft iron; the coil rack is fixed on cylinder inner wall with part of coil in the ring orifice; the elastic or quality component is set in the hot junction pipe; the quality component does shift sliding along the elastic element; the elastic or quality phase modulation component is set in the greenhouse pipe; the quality component does shift sliding along the elastic phase modulation element. The invention can adjust the phase difference of pressure fluctuation and bulk flow fluctuation, which feedbacks the acoustic power to accomplish high effective Stirling cycle as well as inhibits the loop ring current to improve property of entire machine.

A method of producing sound waves. The method includes causing a carbon nanotube structure heat, and thus causing the thermoacoustic effect.

Apparatus comprising at least one transducer comprising a displacement component that is configured to move upon application of an electrical signal; a cavity in communication with the at least one transducer; and at least one thermodynamic member within the cavity configured to readily exchange heat with a cavity gas or fluid, wherein the transducer is configured to generate a standing wave within the cavity to transfer heat along the thermodynamic member.

The invention provides a thermo-acoustic liquid state magnetic fluid alternative electric generation system which comprises a thermo-acoustic motor and a liquid state magnetic fluid alternating current ganerator, the resonatron of the thermo-acoustic motor is coupled on one opening end of the pipe of the liquid state magnetic fluid alternating current ganerator for containing the liquid state magnetic fluid, the pipe is arranged in the magnetic field to make the liquid state magnetic fluid cut the magnetic force line to generate electric energy when flowing in the pipe, the pipe comprises an output electrode for outputing the generated electric energy, which is characterized in that, the working substance of the thermo-acoustic motor is gas working substance. The invention reduces manufacturing difficulty and cost of the prior electric generation system, and the working frequency is suitable, the efficiency is high.

The present invention is a directed to method and system of TCT imaging whereupon data associated with unmeasured or inadmissible transducer locations is determined from data acquired at measured or admissible transducer locations. The invention analyzes measured TCT data associated with several transducer locations to provide an estimate of unmeasured data so as to complete a full data set for image reconstruction. In this regard, by measuring TCT data at many points on the surface of a hemispherical bowl or sphere in which an imaging object is placed, mathematical coefficients may be determined for the TCT data as a function of transducer location. From these coefficients, the unmeasured transducer locations may be evaluated such that data associated with the unmeasured transducer locations may be estimated and utilized for image reconstruction to improve image quality as well as improve the diagnostic sensitivities or capabilities of the TCT system.

The invention discloses a system and a method for measuring temperature in real time based on thermoacoustic effect. A thermoacoustic signal of a detected material is detected by using thermoacoustic imaging equipment; a relation parameter of the temperature of the detected material and the thermoacoustic signal amplitude value is obtained by data fitting; during actual temperature measurement, by using the known fitting parameters and through the relation of the temperature of the detected material and the thermoacoustic signal, the temperature of the detected material is obtained by reversely deducing and analyzing by using a one-dimensional thermoacoustic signal; and finally a temperature distribution figure is displayed on a computer in real time. Combined with the advantages of thermoacoustic technology, the system and the method for measuring the temperature in real time based on the thermoacoustic effect have high accuracy and high spatial resolution, and can quickly obtain temperature change parameters and the temperature distribution figure in real time under the condition of no damage, wherein the temperature measurement accuracy can reach 0.2 DEG C, so a reliable monitoring method and a system device are provided for real-time and nondestructive measurement of material temperature.

Acoustic pyrometry-based active temperature monitoring of gas turbine combustors, including industrial gas turbine (IGT) combustors is incorporated into the combustion monitoring and control system by addition of an acoustic transmitter or acoustic transceiver that transmits a sound wave in a line-of-sight with a plurality of thermoacoustic sensors, such as dynamic pressure sensors. Sound transmission time-of-flight is measured by the controller and correlated with path temperature along the line-of-sight. Path(s) of acoustic transmission serve as absolute temperature measurement that optionally is used for calibrating dominant mode passive bulk temperature measurement. In an integrated thermoacoustic pressure-based sensor and monitoring / control system embodiment, the controller correlates performance of an combustion thermoacoustic properties in order to identify combustion anomalies by wavelet or Fourier analysis techniques, determine bulk temperature characteristics within the combustor with dominant mode frequency analysis techniques and determines absolute active path temperatures within the combustor with acoustic transmission and time-of-flight analysis techniques.

A method and system for estimating fractional fat content of an object of interest. An energy emitter is used to direct an energy signal with an energy signal electric field strength toward the region of interest, wherein the region of interest has an object of interest, a reference, and a boundary between the object of interest and the reference. Next, a thermoacoustic or ultrasonic transducer is used to receive a thermoacoustic bipolar signal from the boundary, wherein the thermoacoustic bipolar signal is induced by the energy signal. Finally, a machine is used to accept data from the energy emitter and thermoacoustic or ultrasonic transducer, correlate the thermoacoustic bipolar signal to an electric field strength of the reference at the boundary to generate a corrected thermoacoustic bipolar signal at the boundary, and calculate a fat concentration of the object of interest as a function of the corrected thermoacoustic bipolar signal at the boundary.

A thermoacoustic device includes a signal device and a sound wave generator. The sound wave generator includes a base structure and a conductive material located on the base structure. The base structure includes nano-scale elements. The signal device is capable of transmitting an electrical signal to the sound wave generator. The sound wave generator is capable of converting the electrical signal into heat. The heat is capable of being transferred to a medium to cause a thermoacoustic effect.