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.

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 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 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.

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.

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.

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.