333 results about "Acoustic wave propagation" patented technology

To perform a non-destructive condition assessment of a pipe carrying a fluid, an actual value representative of the propagation velocity of an acoustic disturbance propagating between two longitudinally separated points on the pipe is determined. A corresponding predicted value for the propagation velocity is computed as a function of at least one wall thickness parameter of the pipe by using a theoretical model for the propagation of acoustic waves in the pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile. The wall thickness parameter is then computed by matching the actual value with the predicted value, for example, by substituting the actual value in a formula predicting the theoretical value.

To perform a non-destructive condition assessment of a pipe carrying a fluid, an actual value representative of the propagation velocity of an acoustic disturbance propagating between two longitudinally separated points on the pipe is determined. A corresponding predicted value for the propagation velocity is computed as a function of at least one wall thickness parameter of the pipe by using a theoretical model for the propagation of acoustic waves in the pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile. The wall thickness parameter is then computed by matching the actual value with the predicted value, for example, by substituting the actual value in a formula predicting the theoretical value.

In a method for producing a boundary acoustic wave device that includes a first medium, a second medium, and a third medium laminated in that order, and electrodes disposed at the interface between the first medium and the second medium, the method includes the steps of preparing a laminate including the first medium, the second medium, and the electrodes disposed at the interface between the first medium and the second medium, adjusting the thickness of the second medium after the step of preparing the laminate to regulate a frequency or the acoustic velocity of a surface acoustic wave, a pseudo-boundary acoustic wave, or a boundary acoustic wave, after the adjusting step, forming the third medium different from the second medium in terms of the acoustic velocity with which the boundary acoustic wave propagates therethrough and / or in terms of material.

The invention discloses a tunable laser system, a acousto-optic tunable filter that utilizes frequency offset compensation. Precision and stability of the output wavelength are realized by a wavelength lock; the wavelength lock utilizes two separated cavity laser beam to avoid using a beam splitter, which reduces requirements to space comparing to a tradition wavelength lock, and running is more stable, and assembly easier. The acousto-optic tunable filter comprises a acousto-optic crystal and a acoustic wave transducer that are bond on surface selected by a crystal to generate acoustic wave;an optical reflector is used for reflecting the diffracted ray back to the acousto-optic medium; because the two incident rays are opposite relative to the acoustic wave propagation direction, the frequency offset generated by the two diffraction is compensated. The invention can be used to produce wideband tunable laser system for various applications with different laser gain medium, acoustic wave drive frequency and acousto-optic crystal.

A method and apparatus for determining formation slowness around a borehole are provided. The Fresnel volume concept is applied for traveltime tomography. The Fresnel volume represents a sonic wave propagation path about the borehole. The application of Fresnel volume to sonic data provides for a stable inversion and makes practical 3-D tomography. Inversion is accomplished by an iterative back-projection method.

Accurately quantifying optical absorption coefficient using acoustic spectra of photoacoustic signals. Optical absorption is closely associated with many physiological parameters, such as the concentration and oxygen saturation of hemoglobin, and it can be used to quantify the concentrations of non-fluorescent molecules. A sample is illuminated by, for example, a pulsed laser and following the absorption of optical energy, a photoacoustic pressure is generated via thermo-elastic expansion. The acoustic waves then propagate and are detected by a transducer. The optical absorption coefficient of the sample is quantified from spectra of the measured photoacoustic signals. Factors, such as system bandwidth and acoustic attenuation, may affect the quantification but are canceled by dividing the acoustic spectra measured at multiple optical wavelengths.

A photoacoustic spectrometer that is intensity-modulated, laser-driven and with a calculable cell constant. The axially symmetrical photoacoustic spectrometer combines first-principles models of acoustic wave propagation with high-resolution spectroscopic measurements, and takes into account molecular relaxation. The spectrometer includes a duct and two chambers disposed at the end of the duct. Inlet and exit tubes, which are disposed in substantially the location of acoustic pressure nodes, permit the gas, gaseous mixture or aerosol to enter and exit the spectrometer. The absolute response of the spectrometer may be modeled and measured. A detailed theoretical analysis of the system and its predicted response may be predicted as a function of gas properties, resonance frequency and sample energy transfer relaxation rates.

A surface acoustic wave (SAW) sensor includes a transducer (240 provided on a substrate (23), wherein the transducer (24) is oriented on the substrate (23) so that the direction of acoustic wave propagation is such that the variation of sensor output with temperature, associated with the variation of the substrate third-elastic constants with temperature, substantially equal but opposite to the sum total of the variation of sensor output with temperature associated with the substrate linear temperature coefficient of expansion and with the variations with temperature of the substrate non-zero third order elastic constants, the substrate first-order elastic constants and the substrate density. The effect of temperature variation on sensor output is thereby minimized. This is achieved with a 35-degree arrangement or with reflective gratings inclined at an angle of 3.1 degrees to normal. Additionally, a robust package with a dish is given. Particular applications include the measurement of torque.

In an acoustic wave filter device, first and second surface acoustic wave filter sections implemented by longitudinally coupled resonators are arranged on a piezoelectric substrate. The first and second surface acoustic wave filter sections include first to third interdigital transducers and fourth to sixth interdigital transducers, respectively, arranged in a direction of propagation of surface waves. The first, third, fourth, and sixth interdigital transducers are connected to an unbalanced terminal. The second and fifth interdigital transducers are connected to first and second balanced terminals, respectively. Each of the second and fifth interdigital transducers has first and second interdigital transducer segments divided in the direction of propagation of acoustic waves. The first and second interdigital transducer segments are connected in series with each other.

The present invention discloses a multi-acoustic circuit time difference type ultrasonic flowmeter, which comprises an upstream transducer, a downstream transducer, a transmitter, a receiver, and a control unit, wherein each upstream transducer and each downstream transducer are all connected with an independent transmitter and an independent receiver, and the transmitter and the receiver are connected in parallel to the control unit and are controlled by the control unit. The present invention is used for monitoring a large sized flow passage, a concurrent high voltage impulse transmitter microporocessor and a control circuit are used to measure a plurality of acoustic circuits, the different transmitter is chosen through a coding bus line, to operate the different acoustic circuits and the forward direction or the reverse direction in the different acoustic circuits. Namely the forward direction or the reverse direction of each passage has the respective transmitter and the corresponding receiving circuit. A relay is not used when the transmitters switch over, thus the switching time between the transmitters is very short; in this way, a multiple impulse technology can be adopted to measure each passage time after time, thereby the precision to measure the propagation time of the ultrasonic is improved.

In an acoustic wave resonator, an IDT electrode is provided on a piezoelectric substrate. The IDT electrode is apodization-weighted such that a plurality of maximum values of cross widths are provided in acoustic wave propagation directions. Alternatively, in apodization weighting, weighting is applied such that at least one of a pair of envelopes located at outer side portions of the IDT electrode in directions substantially perpendicular to acoustic wave propagation directions includes a plurality of angled envelope portions angled from a central portion of the IDT electrode toward an outer side portion of the IDT electrode in a direction substantially perpendicular to the acoustic wave propagation directions.

A method for survey data processing compensates for visco-acoustic effects in TTI medium in an RTM method. This method employs propagating in conjugate medium to yield correct phase, and acoustic wave propagation to yield correct amplitudes through adaptive matching filtering.

To perform a non-destructive condition assessment of a pipe carrying a fluid, an actual value representative of the propagation velocity of an acoustic disturbance propagating between two longitudinally separated points on the pipe is determined. A corresponding predicted value for the propagation velocity is computed as a function of at least one wall thickness parameter of the pipe by using a theoretical model for the propagation of acoustic waves in the pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile. The wall thickness parameter is then computed by matching the actual value with the predicted value, for example, by substituting the actual value in a formula predicting the theoretical value.

An optical fiber for the transmission of electromagnetic energy, where the fiber can have increased input power threshold for the onset of Stimulated Brillouin Scattering (SBS). The fiber can comprise a core and a cladding disposed about the core. The core can have a distribution of velocities for an acoustic wave associated with SBS, where the distribution of propagation velocities of the core for the acoustic wave is at least one of a) azimuthally asymmetric or b) non-constant in an azimuthal plane and longitudinally asymmetric. The fiber can be longitudinally asymmetric wherein the core includes a first portion having a propagation velocity for the acoustic wave that is substantially the same throughout interposed between longitudinally spaced portions each having a propagation velocity different than that of said first portion. Methods, such as, for example, methods for fabricating and / or using a fiber having an increased threshold input power for the onset of SBS, are also disclosed.

The invention relates to a dogging Doppler ultrasonic flow-velocity distribution device, by adopting which the ultrasonic wave sent out from the ultrasonic transducer arranged outside the pipeline is sent on the liquid to be measured in the pipeline to measure the distribution of the flow-velocity of the liquid. The principle of the device is a certain frequency of the ultrasonic wave is reflected by the reflector in the liquid, and due to the Doppler Effect, the frequency is changed according to the flow-velocity. The sound wave propagation wedge of the ultrasonic flow-velocity distribution device is arranged between the ultrasonic transducer and the pipeline. The frequency of the emitted ultrasonic wave is set different from a certain frequency with a wave refraction angle of 90 degrees of the Lamb wave patterns in the pipeline. The frequency is calculated from the angle of incidence of the ultrasonic wave from the wedge into the pipeline, the sound speed in the wedge, the sound speed of the S-wave and P-wave in the pipeline, and the thickness of the pipeline. In such a way, the transmission frequency and the angle of incidence into the pipeline in the ultrasonic flow-velocity distribution device are fully chosen, thus allowing for the high-precision measurement of the fluid flow-velocity or the flow.

A broadband ultrathin sound absorption and sound insulation structure for controlling a sound wave propagation path comprises at least one sound absorption and sound insulation unit, and each sound absorption and sound insulation unit comprises at least one sound wave converging section and at least one sound wave absorption section. The sound wave converging section is formed by a sound wave converging mold cavity filled with acoustics materials, the mold cavity is a variable cross-section mold cavity, the cavity is filled with isotropy or anisotropy acoustics materials, and the anisotropy acoustics materials are formed by acoustic materials embedded into a film or a silk screen. The sound wave absorption section is formed by a sound wave absorption labyrinth channel filled with sound absorption materials, the channel is a labyrinth single-communication channel with a closed or opened end and is communicated with the sound wave converging mold cavity. The sound wave converging mold cavity controls the sound wave propagation path through section changing of the mold cavity and the changing of the material equivalent parameters in the cavity to allow the sound wave to converge and propagate along a curve. The sound wave absorption section employs the ultra-long path of the sound wave absorption labyrinth channel to realize effective sound absorption of the broadband through filled sound absorption materials and arranged period local oscillators.

The invention discloses an aspheric focus method of using an ultrasonic probe to transmit pulse. The method comprises the following steps: A1. arranging M / 2 focuses on the centre line of the acoustic propagation direction of the center bore of the ultrasonic probe, wherein M represents the array number of the transmitting aperture of the probe; A2, calculating the transmitting delay, corresponding to the center bore, of each array of the ultrasonic probe, wherein arrays are focused to the focuses; and A3, controlling the pulse transmitting sequence of each array of the ultrasonic probe according to the transmitting delay. The aspheric focus method of using the ultrasonic probe to transmit pulse focuses the transmitted pulse on a continuous area during primary emission, the sound field on every point of the scanning line within a certain range has better directivity and the flutter fading of the sound field distribution can not caused when the sound field is away the focuses, thus the ultrasound image has more uniform resolution and brightness.

A surface acoustic wave (SAW) sensor includes a transducer (240 provided on a substrate (23), wherein the transducer (24) is oriented on the substrate (23) so that the direction of acoustic wave propagation is such that the variation of sensor output with temperature, associated with the variation of the substrate third-elastic constants with temperature, substantially equal but opposite to the sum total of the variation of sensor output with temperature associated with the substrate linear temperature coefficient of expansion and with the variations with temperature of the substrate non-zero third order elastic constants, the substrate first-order elastic constants and the substrate density. The effect of temperature variation on sensor output is thereby minimized. This is achieved with a 35-degree arrangement or with reflective gratings inclined at an angle of 3.1 degrees to normal. Additionally, a robust package with a dish is given. Particular applications include the measurement of torque.

An optical ultrasonic microphone includes an acoustic waveguide that transmits a sound wave received from an opening, an optical acoustic propagation medium that forms at least one portion of a wall face of the acoustic waveguide and an LDV head, and a sound wave proceeding through the acoustic waveguide is received by the optical acoustic propagation medium so that a change in the refractive index caused by the proceeding sound wave inside the optical acoustic propagation medium is generated with high efficiency, and by detecting this as an optical modulation by the LDV head, the optical ultrasonic microphone is allowed to have a very wide band.

In a balanced acoustic wave filter device, first and second acoustic wave filter sections that are connected in parallel to an unbalanced terminal are connected to first and second balanced terminals, respectively. The first and second surface acoustic wave filter sections are configured such that the phases of the first and second balanced terminals differ by 180 degrees. The first and second acoustic wave filter sections are longitudinally coupled resonator-type acoustic wave filter sections each including a plurality of IDTs disposed in a direction in which acoustic waves propagate. The total number of pairs of electrode fingers of the IDTs in the second acoustic wave filter section in which the polarities of electrode fingers that are adjacent to each other in an area in which IDTs are adjacent to each other are opposite to each other is greater than the total number of pairs of electrode fingers of the IDTs in the first acoustic wave filter section in which the polarities of electrode fingers that are adjacent to each other in an area in which IDTs are adjacent to each other in the direction in which acoustic waves propagate are equal to each other.

The invention discloses a measuring device and method for a hearth velocity field of a combustion boiler by using an acoustic method. 8 groups of acoustic wave transmitters (2) and acoustic wave receivers (3) are uniformly arranged on four walls of a same cross section of a hearth to form 24 interlaced acoustic wave transmission paths in a plane; a plurality of the acoustic wave transmitters (2) are respectively connected with the output end of a power amplifier (1) through an I / O (Input / Output) card (6) of a computer; the power supply ends of a plurality of the acoustic wave receivers (3) are respectively connected with the output end of a switching power supply (4); the signal output ends of the plurality of the acoustic wave receivers (3) are respectively connected with the computer (5) through an A / D (Analog to Digital) card (7); and the computer (5) is connected with a corresponding voice frequency input port of the power amplifier (1) through a D / A (Digital to Analog) card (8). The invention has the advantages of real-time and strong representation property to continuous fields; meanwhile, the technology has no requirements for measured flow field medium and environments, and the measuring device has the characteristics of small size, convenience for installation, low system cost and the like; and particularly, the invention has more advantages in detecting a hearth temperature field of a large coal-fired boiler in a power station.

The invention belongs to the technical field of the nondestructive detection, and relates to improvement of a method for measuring a longitudinal wave velocity of an anisotropic material by adopting an ultrasonic probe. The method is characterized in that a phased-array ultrasonic linear array probe is adopted to measure the longitudinal wave velocity. The method comprises the following steps: acquiring and storing ultrasonic echo data; acquiring a bottom wave propagation time data group of an ultrasonic echo signal; calculating a bottom wave propagation time average value data group; calculating sound wave shortest-path propagation angle data group and a sound wave shortest propagation path data group; calculating a longitudinal wave velocity data group corresponding to each sound wave shortest-path propagation angle; and establishing an analysis function of the longitudinal wave propagation velocity V and the sound wave propagation angle theta. According to the improved method for measuring the longitudinal wave velocity of the anisotropic material, the measurement steps are simplified, the measurement period is shortened, and the measurement precision is improved.

The invention discloses a method for testing the ultrasonic wave velocity of frozen soil under axial pressure. The method comprises the following steps: manufacturing a frozen soil sample; preparing testing equipment; testing the ultrasonic wave velocity of the frozen soil sample under axial pressure; and analyzing the change conditions of the wave velocity of the frozen soil sample under the axial pressure. According to the method for testing the ultrasonic wave velocity of the frozen soil under axial pressure provided by the invention, the damage characteristics in the frozen soil loading process are detected, and the change characteristics of acoustic wave propagation of the frozen soil in the loading process have important guiding significance for predicting the dynamic change of cracks in cold frozen soil engineering and evaluating the stability in China.

The present invention provides a surface acoustic wave device that allows a plurality of surface acoustic wave filters to be formed on a single chip and permits greater miniaturization. The surface acoustic wave device comprises a piezoelectric substrate, a first surface acoustic wave resonator formed on the piezoelectric substrate, and a second surface acoustic wave resonator formed on the piezoelectric substrate in the surface acoustic wave propagation direction of the first surface acoustic wave resonator. The positions in which the first and second surface acoustic wave resonators are formed on the piezoelectric substrate are in an at least partially overlapping relationship in a surface acoustic wave propagation region that is defined by virtually extending the respective openings of the first and second surface acoustic wave resonators. The surface acoustic wave device further comprises a part for dividing the overlap surface acoustic wave propagation region into an upper half and a lower half and for affording the phases of surface acoustic waves that are propagated by the first surface acoustic wave resonator a mutually antiphase relationship in the upper-half region and lower-half region thus divided.

A ladder acoustic wave filter device is constructed such that ripples in the pass band are suppressed, and insertion loss is small in both of a high frequency side portion and a low frequency side portion of the pass band. Apodization weighting is applied to a series-arm-side IDT electrode. Busbars of the series-arm-side IDT electrode are configured so that in an acoustic wave propagation direction, a distance in an overlap width direction between the busbars becomes shorter as the overlap width of electrode fingers becomes smaller. Each of a pair of comb-shaped electrodes of a parallel-arm-side IDT electrode further includes a plurality of dummy electrodes that extend from a busbar and are opposed to electrode fingers of the other comb-shaped electrode in the overlap width direction. The parallel-arm-side IDT electrode is a normal IDT electrode in which the overlap width is constant.

In an acoustic wave filter device, first and second surface acoustic wave filter sections implemented by longitudinally coupled resonators are arranged on a piezoelectric substrate. The first and second surface acoustic wave filter sections include first to third interdigital transducers and fourth to sixth interdigital transducers, respectively, arranged in a direction of propagation of surface waves. The first, third, fourth, and sixth interdigital transducers are connected to an unbalanced terminal. The second and fifth interdigital transducers are connected to first and second balanced terminals, respectively. Each of the second and fifth interdigital transducers has first and second interdigital transducer segments divided in the direction of propagation of acoustic waves. The first and second interdigital transducer segments are connected in series with each other.

The invention relates to the technical field of acoustic telemetry of bidirectional data between the well bottom and the ground during the drilling, in particular to a method for modeling a seamless acoustic transmission channel of a periodic drill rod. The method aims to solve the problem of nonideal transmission effect caused by poor universality of the characteristics of acoustic transmission channels existing in the prior art. To solve the problem existing in the prior art, the invention provides the method for modeling the seamless acoustic transmission channel of the periodic drill rod. Compared with the prior art, the method has the advantages that: a drilling column string acoustic channel propagation model which is seamless and can be freely assembled is developed, is closely combined with the actual field using condition, and has strong applicability and reliable transmission results; the model can perform research and analysis on acoustic wave propagation characteristics of a drilling column string of any drilling tool assembly; and the method establishes acoustic transmission theories for the drilling columns of different drilling tool assemblies, and lays the foundation for developing related instruments in the future.

A computer implemented method including a numerical model of a region of the earth modeling the acoustic behavior of that region. The method implements an acoustic wave propagator allowing the simulation of the propagation of pure P-waves in transversal isotropic media. The propagator can be applied to applications such as seismic forward modeling, reverse time migration and other two-way wave-equation based applications.

The invention provides an echo wall sensor based on sound evanescent field coupling, relates to an acoustic wave biosensor used for biological detection. The sensor includes a membrane structure, a thin-walled round tube resonant cavity, a support device and an excitation receiving device, wherein the thin-walled round tube resonant cavity is supported by the support device; the distance between the thin-walled round tube resonant cavity in a joint excitation echo wall mode and the membrane structure is adjustable; the axis of the thin-walled round tube resonant cavity is parallel to the upper surface of the membrane structure and vertical to the propagation direction of acoustic waves; and the input end and the output end of the excitation receiving device used for exciting and receiving lamb waves are fixed on the membrane structure. The sensor separates the transmission function and the sensing function, and improves the quality factor of acoustic wave resonance in liquid phase, the label-free biosensors of high sensitivity, low detection-limit detection and in integration and array form can be manufactured, and information in the thin-walled resonant cavity in the echo wall mode and related physical information of a to-be-detected object can be obtained through the variation of detection signals.

A SAW element has a substrate; an IDT electrode located on an upper surface of the substrate and comprises Al or an alloy containing Al; a first film located on an upper surface of the IDT electrode; and a protective layer which covers the IDT electrode provided with the first film and the portion of the substrate exposed from the IDT electrode, which has a thickness from the upper surface of the substrate larger than a total thickness of the IDT electrode and first film, and which contains a silicon oxide. The first film contains a material which has a larger acoustic impedance than the material (Al or the alloy containing Al) of the IDT electrode and the silicon oxide and which has a slower propagation velocity of an acoustic wave than the material of the IDT electrode and the silicon oxide.