114 results about "Acoustic wave velocity" patented technology

The invention relates to a method for measuring deep rock-sample initial damage distribution, aiming to provide a simple and feasible method for measuring deep rock-sample initial damage distribution, which can obtain the initial damage distribution situation of a rock sample and further reasonably determine loading mode and loading direction of the rock sample. The method comprises the following steps: processing the rock sample; installing an acoustic detection probe and an acoustic emission probe; carrying out a uniaxial loading test on the rock sample; determining the crack initiating strength of the rock sample; and carrying out comprehensive analysis on three-way acoustic wave velocity and distribution of acoustic emission events of the rock sample, and finally determining initial damage distribution of the rock sample. The method is applicable to a rock mechanical test which serves underground engineering such as deeply-buried hydraulic and hydro-power engineering, traffic, mine and the like.

There is described an electro-acoustic device, comprising a piezo-electric substrate and a first transducer and second transducer supported by the substrate and each including a pair of interdigital transducer electrode arrays, the electrodes of the arrays being interleaved with each other. The first and second transducer are disposed opposing each other in a propagation direction of acoustic waves excited by the first and second transducers. The first transducer has a first electric signal associated with and existing across, and the second transducer has a second electrical signal associated with it which has a different phase from the first electrical signal. The first and second transducers are spaced apart such that substantially in-phase acoustic waves propagating in the substrate and incident on the first transducer in-phase with the first electric signal and on the second transducer in-phase with the second electrical signal. Preferably, the first and second transducers are spaced apart by an integer number of half acoustic wavelengths corresponding to an operating frequency of the device. This permits differential or balanced driving of the device. There is further disclosed examples of such a device utilised in transversely and in-line coupled resonator filters to provide balanced or differential inputs or outputs thereto, and to facilitate cascade connected coupled resonator filters having no ground loops.

The invention discloses a device and a method for monitoring rock sample damage in the uniaxial compression process, which has the benefits that the joint real-time monitoring of acoustic wave, acoustic emission and electromagnetic radiation information in the uniaxial compression test process of a rock sample is realized; based on the three measurement data, different damage variable expression forms are respectively defined; on the basis of fully considering the acoustic wave velocity, acoustic emission and electromagnetic radiation variation law complementarity of the rock sample in the uniaxial compression process, a more reasonable comprehensive damage variable is provided to comprehensively and completely reflect the damage states of the rock sample at different damage stages; compared with a conventional electromagnetic measurement probe, an electromagnetic radiation measuring coil is simpler and more convenient to manufacture and can effectively shield the interference generated by ambient electromagnetic radiation noise, so that measurement results are more accurate; as the total number of turns of leads is changed, and the leads at positions with different numbers of turns are led out outwards and are respectively connected with a plurality of channels of an electromagnetic radiation detector, the simultaneous measurement of electromagnetic radiation signals within different frequency band ranges can be quickly and conveniently realized.

The invention discloses a method and a device for acoustic discrimination of multistage yield points by a rock triaxial single sample method. The upper end and the lower end in a triaxial chamber are respectively provided with an upper rigid pressure head and a lower rigid pressure head; the device is characterized in that an acoustic emission (AE) probe and an acoustic wave probe coupling testing device are respectively and fixedly arranged in the upper rigid pressure head and the lower rigid pressure head in a sealing way, and are used for bearing the high-pressure oil in the triaxial chamber; an AE acquisition system and an acoustic meter are connected; in the rock axial loading process, AE test and acoustic wave velocity test are completed at the same time in the whole process of rock microcrack dynamic propagation until yield failure, and the like; the experiment information data such as AE and acoustic wave can be output by the AE acquisition system and the acoustic meter in the rock failure process; the yield points can be judged jointly according to the propagation of microcrack in rock matrix, the AE characteristic change law near the yield points and the acoustic wave velocity change characteristics; the level of axial pressure loading is controlled to be stopped by a computer, and the next level of axial pressure loading of confining pressure is carried out; the multistage yield points of a rock single sample test piece are sequentially discriminated and tested.

The invention discloses a seismic inversion reservoir prediction method based on decompaction acoustic wave velocity. First, original acoustic wave velocity time difference data are arranged and analyzed, time frequency analysis processing is performed on the data, low-frequency components and intermediate- and high-frequency components are saved respectively, then a low-frequency acoustic wave time difference curve is corrected according to a low-frequency long trend fine adjustment method, the corrected low-frequency components and the originally saved high-frequency components are fused to obtain a new acoustic wave time difference curve after decompaction correction, accordingly a crossplot analysis method is utilized to perform reservoir response characteristic analysis on the corrected acoustic wave time difference, the reservoir acoustic wave response characteristic is clear, and is then converted into acoustic wave velocity as a characteristic curve to carry out reservoir multi-attribute neural network seismic inversion treatment, thereby obtaining an acoustic wave velocity invertomer, and finally, a seismic and geological comprehensive assessment means is adopted to carry out explanation and analysis on the acoustic wave velocity invertomer, thereby obtaining a reservoir qualitative and quantitative prediction result. The seismic inversion reservoir prediction method based on decompaction acoustic wave velocity has the advantages of strong operability and wide application range.

The invention discloses a method for obtaining the undercompaction overpressure in a stratum. The method comprises the steps that 1, firstly, according to the difference change characteristics of theaverage interval transit time, the average stratum density and the average neutron porosity of a mudstone section along with the average buried depth, the normal compaction section and the undercompaction section are determined; 2, then the index relation of the acoustic wave velocity and the vertical effective stress is fitted by utilizing a scatter diagram of the acoustic wave velocity and the vertical effective stress of the normal compaction section; 3, due to the fact that change of the vertical effective stress and the acoustic wave velocity of the undercompaction section needs to fall on a change trend curve of the acoustic wave velocity and the vertical effective stress of the normal compaction section, the acoustic wave velocity of the undercompaction section is substituted into the index relation obtained in the step 2, and the vertical effective stress of the undercompaction section is obtained; and 4, finally, the overpressure value in the undercompaction section is obtained by combining the relation of the vertical effective stress of the undercompaction section and the overpressure. The magnitude of the undercompaction overpressure can be accurately obtained only through logging data, the characteristics of rapidity, simpleness, convenience and accuracy are achieved, and the evaluation efficiency on the undercompaction overpressure is improved.

The optical fiber comprises: (a) a core having a refractive index profile and a centerline; and (b) a cladding layer surrounding and directly adjacent the core; wherein core includes updoping material and is doped with F in at least one region of the core, such that either: (a) the average longitudinal acoustic wave velocity within the core is within 0.05% of the longitudinal acoustic wave velocity within the cladding; or (b) the longitudinal acoustic wave velocity at one region of the core is different from the longitudinal velocity at another region of the core by at least 0.2%.

The invention provides a method for preparing a thin film bulk acoustic resonator based on ferroelectric materials, the thin film bulk acoustic resonator based on the ferroelectric materials and a filter, an oscillator and a radio frequency module comprising the thin film bulk acoustic resonator. The resonator controls change of ferroelectric material stresses by utilizing the electrostriction effect of the ferroelectric materials in a manner of changing externally-added direct voltage, therefore, sound wave velocity can be controlled, however, resonant frequency is in direct proportion to the sound wave velocity, and consequently change of the resonant frequency can be controlled. When the externally-added voltage is zero, the stress is also zero, sound waves can not be generated, resonance can not happen, and therefore devices can be started and stopped by applying the direct voltage or not. According to the scheme, the resonator can be started and stopped and frequency can be adjusted through externally adding of voltage in a simple mode under the condition that an externally-added switch is not needed. A switching filter bank based on the resonator neither needs any externally-added switch nor has insertion loss from the switch or a bias voltage network, and therefore sizes and manufacturing cost of the devices are greatly reduced.

The invention discloses a method and a device for dynamically detecting defects of ballastless track. At first, an acoustic wave excitation unit is used to input vibration energy to a track plate, anacoustic wave in that frequency range of 10 to 20 kHz is generated, and the acoustic wave signal is collected by a microphone sensor and transmit to a computer. The computer calculates the collected acoustic wave velocities and compares the velocities with the threshold values to judge whether there are defects, specifically, if the collected acoustic wave velocities are smaller than the thresholdvalues, the defects are judged. The greater the difference from the threshold is, the greater the defect is. The invention realizes the dynamic detection of ballastless track defects. The invention has the advantages of fast detection speed, high efficiency, long-distance detection operation in several hours of skylight time, basically no influence of external environment on the detection result,high detection precision, and the defect position can be marked at the same time so as to facilitate later maintenance and repair, so that the detection and maintenance work efficiency is greatly improved.

The invention discloses a full-waveform inversion method based on dynamic random seismic source coding. The invention discloses a dynamic random seismic source coding new strategy, belongs to the field of geophysics, and provides a dynamic random seismic source coding new strategy by randomly selecting four aspects of amplitude, phase, polarity and shot point position of a seismic source, which comprises the following main steps of: randomly selecting actual shots and time coding sequence convolution, and synthesizing a super shot profile; calculating a super shot residual error, a gradient direction and an optimal step length; inversion iteration is carried out, and target parameters are updated; and judging whether an inversion termination condition is met or not. Crosstalk noise betweenshots is avoided, and the inversion efficiency is greatly improved on the premise that the inversion precision is not affected. The new dynamic random seismic source coding strategy is introduced into the solution of the L-BFGS algorithm of the variable density acoustic wave equation full waveform inversion, the crosstalk influence of the medium density and the acoustic wave speed during the synchronous inversion is effectively reduced, and the full waveform inversion speed is improved.

The invention discloses a non-destructive experimental evaluation method for the damage degree of heterogeneous compact rocks, which comprises: (1) testing the initial acoustic wave velocity of a rocksample and converting it into an initial dynamic Young's modulus and an initial dynamic Poisson's ratio; (2) testing the porosity, pore size distribution and stratified moisture content of the rock sample; (3) performing high temperature and high pressure working fluid damage treatment on the rock sample; (4) testing the acoustic wave velocity of a damaged rock sample and converting it into a dynamic Young's modulus and a dynamic Poisson's ratio; (5) testing the porosity, pore size distribution and stratified moisture content of the damaged rock sample, and analyzing the physical properties,pore structure changes, and the depth of working fluid intrusion of the rock sample; (6) calculating a damage variable of the rock sample; (7) Fitting the relational formula between the damage variable of the rock sample and the dynamic Young's modulus and the dynamic Poisson's ratio, and evaluating and predicting the mechanical damage of the working fluid. According to the non-destructive experimental evaluation method for the damage degree of heterogeneous compact rocks, the problem of damage evaluation of heterogeneous dense rock is solved thereby providing technical guidance and theoretical basis for the optimization design of drilling and completion.

The invention discloses a least square migration imaging method and device based on an L-BFGS algorithm. The method comprises steps of performing reverse time migration imaging according to an acoustic velocity model of a target exploration area and a common shot point record of the acoustic velocity model to obtain the initial imaging result; calculating record residual errors of the synthetic seismic record and the original observation record of the target exploration area according to the initial imaging result; calculating the gradient of a target functional relative to the initial imagingresult according to the record residual error; obtaining the second imaging result through an L-BFGS algorithm according to the initial imaging result and the gradient of the target functional with respect to the initial imaging result; and judging whether the record residual error and the calculation frequency of the L-BFGS algorithm meet a preset termination condition or not. The method is advantaged in that the optimal solution method of the L-BFGS is introduced, so the optimization process is prevented from falling into local optimization in the solving process of a nonlinear optimizationproblem, and the optimization process in the aspect of nonlinear optimization is more stable.

A device for manipulation of acoustic waves is provided, comprising a functionally-graded material for interposing between a source of the acoustic waves and a target, which may be a detector of manipulated acoustic waves. The functionally-graded material has a gradient in acoustic wave velocity which is obtained by the generation of a gradient in at least one of the following properties: elastic modulus, Poisson's ratio, and density, that is perpendicular to a direction of propagation of the acoustic waves. The gradient is axial. Biaxial acoustic velocity gradients may be used for focusing/waveguiding (high-low-high) or dispersing (low-high-low), while monoaxial acoustic velocity gradients may be used for wave steering. Also in accordance with the present invention, a method of making the device is provided, comprising: (a) providing the source of acoustic waves; (b) providing the target for acoustic waves, e.g., detector of manipulated acoustic waves; (c) providing the functionally-graded material having a gradient in at least one material property; and (d) interposing the functionally-graded material between the source of acoustic waves and the target for acoustic waves such that the gradient is perpendicular to a direction of propagation of the acoustic waves. The functionally-graded material so provided can be used to manipulate, i.e., focus, disperse, steer, waveguide acoustic waves for applications such as, acoustoelectronics, acoustooptics, SONAR, ultrasonic imaging, non-destructive testing (NDT), etc.

The invention discloses a multi-type hydrate generation monitoring test method. A gas consumption metering module, a multi-type hydrate sample preparation module, a resistivity parameter test module,and an acoustic parameter test module are designed, conditions for simulating the environmental pressure and temperature, the sediment filling mode and gas-liquid ratio are designed, and multi-type natural gas hydrate reservoirs are synthesized; with the electrical resistance tomography technology, three-dimensional distribution of hydrates in the core is detected to realize internal visualizationof the core; and an acoustic wave tester detects longitudinal and horizontal waves of the core of the hydrate sediment core to obtain a relationship between acoustic wave velocities and hydrate distribution of different types of hydrate reservoirs. Therefore, the test method has the important significance in understanding the physical parameters of occurrence states being different types of reservoirs of the natural gas hydrates in nature correctly and establishing an accurate quantitative relationship between the hydrate saturation and basic physical properties of the reservoir.