114 results about "Acoustic wave velocity" patented technology

An optical fiber comprising a core having a refractive index profile and a centerline; and a cladding layer surrounding and directly adjacent the core; wherein core includes updoping material and is doped with Aluminum 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 in the core changes by at least 0.2%.

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 provides a method for continuously measuring an acoustic wave velocity in a rock compressed crack propagation measurement process. An acoustic wave transmission probe and an acoustic wave receiving probe are fixed on the lateral side of loading a sample, and the time that the acoustic wave propagates along a direction vertical to the loading direction in a rock sample is continuously recorded by adopting a data continuous automatic recording system, so that the radial acoustic wave velocity of the rock sample in the whole uniaxial compression loaded crack propagation process is continuously measured. The acoustic wave velocity in the main direction of vertical crack development in the crack propagation process is continuously measured, so that technical support is provided to the acoustic elasticity research and application in the whole process of generating, propagating and penetrating the crack in the rock sample loading process.

A laboratory test method employs maximum acoustic wave velocity to determine cure time of a sample of curable resin-coated proppant (CRCP) that are packed in a pressurized chamber to simulate conditions in a reservoir rock formation during fracturing in which the CRCP will be used. The pressurized CRCP is subjected to a varying temperature profile that replicates the reservoir temperature recovery during shut-in of the fractured zone in order to develop maximum proppant pack strength and minimize proppant flow back following completion of the fracturing operation and to determine shut-in time to complete curing of the resin.

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 invention discloses a detection system for determining damaged parts of a concrete structure by acoustic-emission computed tomography. The system comprises a multichannel acoustic-emission acquisition system, a movable detection plate and a PLC controller, which are successively connected. According to the movable detection plate, one face is provided with 8-16 multifunctional preamplifiers and 8-16 low frequency sensors which are arranged in a ring array on a concrete structure, and the other face is provided with a fastening device which is compressed on the concrete structure. Each multifunctional preamplifier is corresponding to one low frequency sensor. A Matlab software platform is arranged inside the PLC controller. By using acoustic emission events as point sources, the Matlab software platform obtains slowness graphs of acoustic wave velocity variation reconstructed object structure defects according to the set ART algorithm reconstruction technique, so as to determine the damage locations of the concrete structure. According to the detection system, slowness graphs of the concrete structure in various directions can be timely obtained as much as possible through the acoustic emission technique in the concrete detection system, and each defect structure of the concrete structure can be more accurately detected.

The invention discloses a surface acoustic wave device, which divides the interdigital transducer bus bars into a gap region, an edge region and an intermediate region, and the directions from any busbar to the two bus bars are the gap region, the edge region and the intermediate region in turn. By arranging the hill layer covered by the electrode between the piezoelectric substrate and the electrode, the acoustic wave velocity in the gap region is larger than the acoustic wave velocity in the intermediate region, and the acoustic wave velocity in the intermediate region is larger than the acoustic wave velocity in the edge region. The waveform propagated between the interdigital transducers can be filtered into the piston waveform by the above arrangement, thereby filtering the remainingwaveforms of the non-piston waveform, thereby effectively reducing the parasitic mode of the surface acoustic wave device, and enabling the surface acoustic wave device to have a higher quality factor. The invention also provides a preparation method of a surface acoustic wave device, and the surface acoustic wave device prepared by the method also has the beneficial effects.

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 discloses a liquid-nitrogen circulation cold-shock permeability increasing method based on multi-parameter monitoring. A video monitoring lens is used for shooting and monitoring the size of bubbles generated in liquid nitrogen in a layer-through borehole and the flow rate of generated bubbles in real time and feeding the size of the bubbles and the flow rate back to a monitoring control center for storage; a mass sensor monitor the mass loss rate of liquid nitrogen in the layer-through borehole in real time and feeds the mass loss rate back to the monitoring control center for storage; and a gas monitoring device detects gas pressure, gas flow and gas temperature in a pressure relief pipe in real time and feeds the gas pressure, the gas flow and the gas temperature back to the monitoring control center for storage; after one-time cracking is completed, a SF6 gas detector, an acoustic wave transmitter and an acoustic wave receiver are used for detecting the permeability increasing cracking effect, that is, the acoustic wave speed can be used for detecting the number of cracks generated after permeability increasing, and the SF6 gas can be used for detecting the mutualconnectivity of the cracks. By monitoring the data, the cold shock of liquid nitrogen, the expansion pressure of phase change gas and cracking of a coal body by means of frost heaving pressure of moisture in the cracks are achieved, and the permeability increasing effect can be effectively monitored.

The invention discloses a method for detecting shield channel influence area karst under a building. A horizontal directional drilling machine is utilized to horizontally drill holes in the peripheryof a channel to be built, then in a receiving well, an ultrasonic wellbore imager performs cross-hole pullback in drill holes as an acoustic source, and cross-hole acoustic waves acquired by the ultrasonic wellbore imager are acquired through a data acquisition instrument to form CT input data; and acoustic wave tomographic inversion is performed on the CT input data, mapping software is utilizedto display a cross-hole acoustic wave tomographic map, and finally, a karst distribution situation in a channel range under the building is analyzed based on acoustic wave velocity difference of a detection target and surrounding rock thereof and an attenuation law in an elastic wave propagation process. The karst detection method can overcome limitation of site conditions, an anti-interference capability is high, detection precision and resolution are high, a karst development situation in the subway tunnel range under the building can be precisely detected, risks of construction of the tunnel underneath passing the building are reduced, and the method has good social benefits and economic benefits.

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%.

An optical fiber made of silica-based material includes a core and a cladding formed around the core. The core is doped with germanium dioxide, which increases refractive index and decreases acoustic-wave velocity, and aluminum oxide, which increases both refractive index and acoustic-wave velocity, satisfying −2.814+0.594×W1≦W2≦54.100+0.218×W1, W1+W2≦60, and W2≧56.63−2.04×W1, where W1 is doping amount of germanium dioxide in weight percentage, which is larger than 4.74, and W2 is doping amount of aluminum oxide in weight percentage. A nonlinear coefficient of the optical fiber is equal to or larger than 2.6×10−9W−1.

The invention discloses a transducer for detecting a rock mass acoustic wave. The transducer comprises a transmitting transducer (1), a receiving transducer (2), a rigid connection pipe (3), a measuring bar (4), a hydraulic pump (8) and an acoustic wave collecting device (9), wherein the transmitting transducer (1) is connected with the receiving transducer (2) through the rigid connection pipe (3); the top end of the transmitting transducer (1) is connected with the measuring bar (4). The transducer has the advantages that dry hole detection of an acoustic wave test is achieved under the condition that a coupling agent does not need to be introduced through direct contact of a scalable hydraulic contact and hole wall rock mass of a detection hole; the transducer is not affected by water supply for construction, and drilling azimuth and angle, and can adapt to various detection conditions on the scene; the coupling pressure is controlled through hydraulic equipment with a pressure gage, and the consistence of the coupling conditions can be ensured. The effect of the coupling agent is removed, and the consistence of the coupling conditions is ensured, so that the data in the aspects of acoustic wave amplitude, frequency spectrum and the like also can be obtained besides the condition that the waveform jump point can be accurately judged to obtain acoustic wave velocity data in the acoustic wave test by using the device provided by the invention.

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 provides a method used for calculating rock damaged degree under explosion effects based on nuclear magnetic resonance. The method is used for measuring internal damage degree of rock inexplosion vibration influenced regions. The method comprises following steps: sampling points at equal intervals are selected taking an explosion source as a circle center; rock samples are collectedat the sampling points, and are prepared into rock test pieces to test the uniaxial compressive strength, the longitudinal wave velocity, and the nuclear magnetic resonance times; cement test pieceswith a mechanical property tolerance range ranging from 5 to 8% are prepared based on the mechanical properties of the rock test pieces, the cement test pieces and the rock test pieces are subjected to pre-embedding at sampling points, and explosion vibration data acquisition is carried out; the rock test pieces and the cement test pieces are subjected to uniaxial compressive strength test and acoustic wave velocity test; influence laws of explosion vibration on rock damage increment are obtained based on nuclear magnetic resonance images and the transverse relaxation time so that rock damagedegree under different explosion vibration effects is determined, explosion design is guided, low energy consumption and high efficiency explosion operation are realized, and influences of explosion vibration on non-action object engineering are reduced.

The invention relates to a well periphery seismic imaging detection method and device based on logging while drilling and stratum grillwork constraints. Acoustic velocity data acquired by staged welllogging in the drilling process are utilized, an offset velocity field around a well hole is updated under the constraint of a stratigraphic framework; wave equation datum plane continuation is combined to achieve rapid imaging of depth offset around the well, a drilling target is relocated, and a drilling track is optimized in time. Compared with the prior art, the well periphery seismic imagingdetection method and device has the following advantages: geological reasonability can be achieved when the stratum speed provided by well logging data can be expanded from a borehole to the peripheryof the well, and the drilling success rate is increased.

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.

The invention belongs to the field of geophysical exploration, and discloses hydrate stratum earthquake physical simulation test equipment and method based on a reflected wave field, and the equipmentcomprises a hydrate preparation device and a reflected sound wave test device. The hydrate preparation device is used for generating simulated hydrate; the reflected sound wave testing device is usedfor continuously emitting ultrasonic waves to the simulated hydrate in the generation process, receiving reflected waves, performing signal processing on the received reflected waves to identify andextract reflection characteristic information and acoustic velocity change information, and continuously monitoring the saturation degree of a simulated hydrate to obtain a corresponding relationshipbetween the reflection characteristic information and the acoustic velocity change information and the saturation degree of the simulated hydrate. According to the equipment and the method, hydrate stratum reflection characteristics and sound wave speed changes are acquired through hydrate stratum reflection wave field acquisition, the relationship with the hydrate saturation is obtained, and theequipment and the method have relatively important guiding significance for gas hydrate offshore seismic exploration data interpretation and gas hydrate saturation estimation.

The invention discloses a well-surrounding near-well-wall stratum damage evaluation method based on logging information. The method comprises the steps: calculating a rock anisotropic rigidity coefficient according to full-wave-train dipole acoustic logging information; calculating the elastic modulus, Poisson's ratio and Thomsen coefficient of the rock and the flexibility coefficient of the rock; according to the full-wave-train dipole acoustic logging information, obtaining the radial section of the acoustic velocity of the stratum around the well wall; calculating the flexibility tensor variable quantity of any position close to the well wall; and according to the flexibility tensor variable quantity of any position near the well wall, calculating dispersion damage parameters of stratum rocks at any position near the well wall. According to the method, acoustic logging is adopted to evaluate the damage characteristics of the stratum close to the well wall, the stratum is regarded as a transverse isotropic medium, and acoustic logging information is utilized to calculate and analyze rock mechanical parameters, Thomsen anisotropy coefficients and mechanical damage parameters of different lithology and different radial positions; and the method plays a very important role in ground stress evaluation, borehole wall stability analysis, hydraulic fracturing and the like.