79 results about "Interface waves" patented technology

A passive method for exploring a region below the surface of the earth. The method comprises using a plurality of sensors to obtain seismic data obtained by recording ambient seismic interface waves in a frequency range whose lower limit is greater than 0 Hz, and whose upper limit is less than or equal to substantially 1 Hz. The sensors may be sensitive to three orthogonal components. Recordings may be made simultaneously by all sensors and normalization of data is unnecessary. The sensors may be moved and clean data may be selected. Local dispersion curves may be determined to improve vertical resolution. The data are processed so as to obtain a measure of the energy in a frequency band within the frequency range. The energy measure may be calculated by integrating the spectrum in the frequency domain over a desired frequency range. The resulting calculated energy provides information about the region of the earth being explored.

A passive method for exploring a region below the surface of the earth. The method comprises using a single sensor located in turn at a plurality of locations to obtain seismic data obtained by recording ambient seismic interface waves in a frequency range whose lower limit is greater than 0 Hz, and whose upper limit is less than or equal to substantially 1 Hz. The data are processed so as to obtain a measure of the energy in a frequency band within the frequency range. For example, the seismic data may be filtered and may be subjected to amplitude normalization before being transformed into the frequency domain. The energy measure may then be calculated by integrating the spectrum in the frequency domain over a desired frequency range. The resulting calculated energy provides information about the region of the earth being explored.

The invention relates to monitoring of fluid-filled domains in various media including, for example, subterranean formations, construction elements, bones. Claimed are a method for determining characteristic sizes of a fluid-filled crack in a medium and a system for implementation thereof. In accordance with this method, oscillations of the fluid-filled crack are registered. Wave characteristics of standing interface waves propagating along the fluid-filled crack surfaces are determined based on the registered oscillations taking medium and fluid properties into account. The fluid-filled crack characteristic sizes are calculated based on the determined wave characteristics of the standing interface waves. Also claimed are methods for detecting creation or existence of a fluid-filled crack in a medium, for hydraulic fracturing in a subterranean formation, for detecting cessation of propagation of a fluid-filled crack in a medium, as well as a method for determining properties of a fluid filling a layer in a medium, of the medium and of the layer. Analysis of oscillations of fluid-filled domains based on interface waves propagating along their surfaces underlies all the methods listed above. The proposed methods, by virtue of the simplicity of data processing inherent thereto, can be implemented in real time.

The invention discloses a nondestructive testing method for peel-off of an oxidation layer on the inner wall of a boiler tube. The method comprises the following steps: coating a polished point with a coupling agent, using a high frequency probe to be in contact with a to-be-detected point, catching an interface wave between the oxidation layer on the inner wall of the boiler tube and a metal layer, displaying the thickness transmission sonic path distance of an oxide skin on the inner wall of the boiler tube of the detected point by an oscilloscope, and after the testing, converting the measured sonic path distance by the oscilloscope into the thickness value of the oxide skin on the inner wall. If the measurement result differences of the thickness values of the oxide skin on the inner wall are larger when the probe is moved within a small range near the to-be-detected point, the oxidation layer of the point is indicated to be peeled off.

The invention relates to a crack detection method for a double-layer metal compound pipe based on an interface wave. The method comprises the following steps: analyzing a signal which is generated by a surface wave acting on the double-layer metal compound pipe, thereby confirming if a crack exists, and if the crack exists, and further confirming an axial position and a circumferential position of the crack by utilizing the surface wave which is converted into the interface wave on a joint surface of an inner layer metal pipe and an outer layer metal pipe. The interface wave is free from frequency dispersion in the diffusing process on the joint surface of the metal compound pipe, the energy is concentrated on the interface, the interface wave is sensitive to the damages, such as, cracks, on the interface, the model number of the interface wave in the metal compound pipe is less and the recognition for a crack reflected signal in the signal processing process is benefited, so that the validity and accuracy of the crack recognition and positioning can be increased. According to the invention, the detection operation is convenient, the recognition for the damage on the interface of the whole compound pipe can be realized by stimulating and receiving the signal at one end of the pipe and the crack detection efficiency is increased.

The invention discloses a method, device and system for measuring material mechanical property information. The method includes the steps that excitation signals of different frequencies are loaded toa material to be measured; motion information of surface wave signals or interface wave signals of the material to be measured under different frequency excitation signals are measured, wherein the motion information includes wave velocity and dispersion information, and the surface wave signals or the interface wave signals are ultrasonic signals of the surface or internal interface of the material to be measured and collected by at least two ultrasonic transducers; the mechanical property information of the material to be measured is determined according to the motion information of the surface wave signals or the interface wave signals of the material to be measured under different frequency excitation signals; and the mechanical property information of the material to be measured is output. Based on the fact that the ultrasonic transducers measure the motion information of surface waves or interface waves of the material, the inversion of the mechanical property information of a thin film wrapping material or other wrapping materials or materials in a special environment is realized.

The invention provides an ultrasonic detection method and system used for wheels of a railway vehicle and based on interface wave correlation detection. The method comprises the following steps: an incident probe transmits an ultrasonic pulse signal to a flaw detection surface of a detected workpiece; a first amplifier receives an echo signal reflected by the flaw detection surface of the detected workpiece and amplifies a flaw wave signal in the echo signal, and a second amplifier receives the echo signal reflected by the flaw detection surface of the detected workpiece and amplifies an interface wave signal in the echo signal; an interface wave searcher searches an interface wave according to a preset interface wave gate range; an interface wave judger judges whether the interface wave within the interface wave gate range exceeds a preset interface wave gate height or not; when the interface wave exceeds the interface wave gate height, a flaw wave searcher is triggered and searches flaw wave information according to a preset flaw wave gate range. The ultrasonic detection method and system provided by the invention can guarantee triggering of the interface wave on the premise of not generating a false alarm, and is accurate and reliable.

The invention relates to a method and apparatus for measuring the thickness of the intermediate layer of a three-layer composite plate. By means of the interface wave transmitted between the interfaces, the intermediate layer of the three-layer composite plate is excited to generate and receive a guided wave signal, and by means of the guided wave signal, the interface wave velocity is measured, and by changing the frequency of the excitation signal several times, the dispersion curve of the interface wave transmitting in the composite plate can be obtained, and the group velocity stable corner frequency can be found; By means of the consistence of the interface wave group velocity and the phase velocity stable corner frequency, by taking the product (namely frequency thickness product) of the phase velocity stable corner frequency and the thickness of the intermediate layer of the three-layer composite plate as a constant value, and by means of the principle that the phase velocity stable corner frequency is related to the thickness of the intermediate layer, in the case of known stable corner frequency, the frequency thickness product is divided by the stable corner frequency to obtain the accurate thickness of the intermediate layer of the three-layer composite plate The measurement method is simple and easy, high in measurement precision, and reliable in measurement result, and is suitable for the accurate measurement of the intermediate layer of the three-layer composite plate.

A boundary acoustic wave device includes an IDT electrode between a piezoelectric layer and a dielectric layer. A low thermal expansion medium layer having a linear thermal expansion coefficient less than that of the piezoelectric layer is laminated on the piezoelectric layer opposite to the boundary. Acoustic velocities of transversal waves at the piezoelectric layer, the dielectric layer, and the low thermal expansion medium layer satisfy Expression (1), and (an acoustic velocity of a transverse wave at the dielectric layer) / λ satisfies Expression (2) as follows:(acoustic velocity of transverse wave at dielectric layer)<(acoustic velocity of SH wave at piezoelectric layer)<(acoustic velocity of transverse wave at low thermal expansion medium layer)  Expression (1), and(response frequency of boundary acoustic wave)<(acoustic velocity of transverse wave at dielectric layer) / λ<(response frequency of high order mode)  Expression (2).

The invention relates to a micro-defect ultrasonic detection signal processing method considering surface roughness. The method comprises the following steps that: S1, a detection system is built to obtain micro-defect ultrasonic detection signals under the influence of a rough surface; S2, a coif4 wavelet generating function is adopted to perform N-layer wavelet decomposition on the micro-defectultrasonic detection signals so as to obtain the approximate component of the Nth layer of a wavelet coefficient as well as the detail components of the first layer to the Nth layer of wavelet coefficients; S3, threshold quantization denoising processing is performed on the detail components of the first layer to the Nth layer; S4, inverse wavelet transformation is adopted to perform reconstruction so as to obtain denoised micro-defect ultrasonic detection signals; and S5, the size and position of a micro-defect are judged according to the amplitude of the denoised micro-defect ultrasonic detection signals and the flying time of the denoised micro-defect ultrasonic detection signals relative to interface waves. According to the micro-defect ultrasonic detection signal processing method considering surface roughness of the invention, a plurality of layers of wavelet coefficients which are obtained based on coif4 wavelet mother generating function-based decomposition can express originalsignal characteristics more accurately and efficiently, and background noises caused by the multi-scattering of the micro-defect detection signals and the sound waves of the rough surface are effectively distinguished.