328 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.

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 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.

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.

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 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.

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 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 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.

A system and method for predicting active, low-frequency sonar array performance in shallow, littoral waters using a physics-based modeling of acoustic reverberation. An operator characterizes the active sonar's acoustic transmitter and receiver, the environment it is operating in and the targets to be detected. The operator selects appropriate bathymetry, bottom composition and sound-speed profile. The spatial resolution of the bathymetry database is enhanced using fractal interpolation and a bottom-loss-and-scattering corrected-for-slope is calculated. A semi-empirical scattering strength is derived from a wind-speed data base and a stochastic biologic realization is derived from a biologic population database. These are then used to calculate a deterministic component of bottom, surface and volume reverberation using a normal mode mathematical model of acoustic wave propagation. A stochastic realization of clutter is calculated using a Generalized Gamma distribution database, and combined with the deterministic components of reverberation.

The invention belongs to the technical field of pipeline leakage detection, in particular to a heat supply pipeline leakage detection system based on infrasound waves and a reference point. The heat supply pipeline leakage detection system comprises a center control system, an upstream acoustic wave monitoring device, a downstream acoustic wave monitoring device and an acoustic source device. Thedistance between the upstream acoustic wave monitoring device and the downstream acoustic wave monitoring device is fixed. The acoustic source device is located on a pipeline between the upstream acoustic wave monitoring device and the downstream acoustic wave monitoring device, and the distance between the acoustic source device and the upstream acoustic wave monitoring device is fixed. The upstream acoustic wave monitoring device, the downstream acoustic wave monitoring device and the acoustic source device are all connected with the center control system through wired network or wireless network for two-way data communication. According to the heat supply pipeline leakage detection system based on the infrasound waves and the reference point, the velocity of acoustic wave propagation inthe pipeline can be measured online by detecting an acoustic wave signal emitted from the reference point, when a pipeline leakage accident occurs, the calculation accuracy of a leakage location canbe significantly improved by calculating the leakage location at the acoustic wave transmission velocity, and the site survey workload of maintenance personnel is greatly reduced.