241 results about "Propagation time" patented technology

The invention relates to the technical field of underwater detection, and discloses an underwater comprehensive detection system. The system collects multi-dimensional acoustic data including sound wave reflection intensity, propagation time delay and frequency dispersion characteristics of a target water area through an underwater sonar array; dividing the detection area into a plurality of layered units according to a water attenuation coefficient and a substrate reflection characteristic of the acoustic data, and extracting an environment intrinsic parameter of each layered unit; constructing an acoustic propagation path model based on the environmental intrinsic parameters, and generating adaptive filtering parameters in combination with a preset noise suppression strategy; calling sonar array hardware configuration data, matching filtering parameters with an array beam forming mode, and calculating a detection sensitivity threshold value of each layered unit; and integrating the sensitivity threshold and the acoustic data, generating a three-dimensional acoustic characteristic spectrum of the target water area, and marking the space coordinates and confidence level of the abnormal area. The system can improve the comprehensiveness and accuracy of underwater detection, and meets the requirement of high-precision detection.

The invention relates to the technical field of safety monitoring, and provides an oil and gas pipeline leakage monitoring method and system, a medium and equipment, and the method comprises the steps: obtaining a leakage vibration signal of each measurement point of an oil and gas pipeline, and extracting a time domain feature, a frequency domain feature, a spatial-temporal feature and an initial distance from a leakage point to a starting end of an optical fiber; performing cross-correlation analysis on the leakage vibration signals of the adjacent measuring points to obtain a propagation time difference and a cross-correlation coefficient, and calculating a correction distance from the leakage point to the starting end of the optical fiber; if the leakage point is in the spiral section, calibrating the correction distance to obtain a calibration distance; calculating the difference value between the initial distance from the leakage point to the optical fiber starting end and the corrected distance to obtain a preliminary positioning error value; and based on the time domain feature, the frequency domain feature and the spatial-temporal feature, in combination with a cross correlation coefficient, a calibration distance, an amplitude enhancement coefficient and a preliminary positioning error value, obtaining a leakage medium type through a medium identification model. The method gives consideration to the positioning efficiency and precision, and greatly improves the accuracy and robustness of a leakage medium type recognition result.

The invention relates to an ultrasonic phased array full-focusing imaging method for acoustic wave multi-path propagation compensation of a layered composite material, which is characterized by comprising the following steps of: arranging an ultrasonic phased array probe with N array elements on a composite material piece to be detected, obtaining complete echo data by taking each array element as a transmitting array element and taking all array elements as receiving array elements in sequence in a full-matrix acquisition mode; a two-dimensional pixel grid is established in an imaging area, a Monte-Carlo perturbation mechanism used for representing the acoustic wave propagation uncertainty in the layered composite material is introduced into a propagation model for each emission array element-receiving array element-pixel point combination, and the acoustic beam emission direction, the propagation path and the equivalent acoustic velocity are subjected to random perturbation, so that the acoustic wave propagation uncertainty in the layered composite material can be represented. Generating a plurality of equivalent sound wave propagation paths, calculating two-way propagation time of each path, and performing weighted statistics on energy contributions of different paths according to array element sound beam directivity to obtain equivalent propagation time delays of pixel points; and performing delay correction on a full-matrix echo signal by using the equivalent propagation time delay, and performing coherent superposition on signals of all transmitting-receiving array element combinations to realize dynamic focusing of a full-pixel grid, and finally reconstructing an ultrasonic full-focusing imaging image with high resolution and high signal-to-noise ratio. The time delay error caused by propagation path deviation and sound velocity non-uniformity in the layered composite material can be effectively compensated, the focusing precision and spatial resolution of full-focusing imaging are improved, meanwhile, an existing TFM imaging frame does not need to be changed, and the method has good engineering implementability and popularization and application value.

The invention belongs to the technical field of power equipment signal processing, and particularly relates to a multi-channel signal reverberation suppression method based on phase weighted cross-correlation optimization, which comprises the following steps: S1, acquiring an original multi-channel time domain signal matrix; s2, estimating propagation time delay of each channel relative to the reference channel; s3, enabling all channels to realize time domain alignment in a direct sound main energy section; s4, processing to obtain a multi-channel time-frequency domain signal; s5, performing reverberation suppression by adopting a WPE algorithm to obtain a multi-channel time-frequency domain signal after reverberation removal; before the WPE algorithm is executed, through a Bayesian optimization method based on a Gaussian process, a prediction order and prediction delay parameter combination enabling the SI-SNR of the multi-channel dereverberation signal to be maximum is searched, and the prediction order and prediction delay parameter combination is applied to the WPE algorithm; s6, reconstructing the multi-channel time-frequency domain signal after reverberation removal into a time domain signal; and S7, calculating a normalization coefficient, and performing amplitude scaling. According to the method, the dereverberation ultrasonic signal with high fidelity, high consistency and high robustness can be obtained in a complex reverberation environment.

The invention provides a high-precision three-dimensional ultrasonic wind speed measurement method and device, the method is applied to an ultrasonic transducer array, a plurality of transducers in the transducer array are arranged according to a non-orthogonal structure to form a plurality of acoustic measurement paths, and the specific steps are as follows: acquiring ultrasonic signals collected on the plurality of acoustic measurement paths; for each acoustic measurement path, determining a downwind and upwind propagation time difference of ultrasonic waves on the path based on cross-correlation operation and sine wave fitting; and calculating a three-dimensional wind speed vector based on the geometrical relationship of each acoustic measurement path and the corresponding propagation time difference, thereby achieving the technical effects of remarkably improving the anti-interference capability, greatly improving the measurement precision, remarkably improving the calculation speed, optimizing the spatial symmetry, enhancing the environmental adaptability and improving the measurement robustness.

The invention discloses an anti-electromagnetic interference coding method and system for a pulse sequence of an ultrasonic flowmeter, and relates to the technical field of industrial measurement. The method comprises the following steps that a pulse sequence of the ultrasonic flowmeter in the working process is obtained; the pulse sequence is processed, and the electromagnetic interference type is identified through machine learning; constructing a final feature matrix based on feature enhancement of an acoustic-electric coupling factor; a dynamic coding generation strategy: receiving an original pulse sequence output by the TDC chip, and selecting a coding scheme according to the current interference type; and error feedback calibration is carried out by adopting a bidirectional propagation time correction formula. Real-time interference classification is carried out through machine learning, and FPGA hardware completes level coding switching, so that a signal spectrum dynamically avoids an interference frequency band, and the anti-electromagnetic interference capability of the ultrasonic flowmeter is improved.

The invention discloses a ring main unit cable line fault positioning system and method based on traveling wave intelligent sensing, and relates to the technical field of ring main unit cable line fault positioning, and the method comprises the following steps: arranging a traveling wave sensor at a position corresponding to a cable connecting plug or a solid-sealed polar pole in a ring main unit; an initial correction stage is carried out, a known electrical event is triggered on a cable in actual operation, the propagation time of a traveling wave signal between the two ends is measured, and the wave velocity of the traveling wave is actually measured on site and dynamically updated in combination with the known cable length; the method comprises the following steps: executing initial correction under different operation conditions, collecting corresponding data of working conditions and wave velocities, constructing a self-adaptive model of the wave velocities and working condition parameters, and when a fault occurs, dynamically predicting the wave velocities based on the constructed model according to current working condition parameters monitored in real time; and on the basis of the identified wave head timestamp, constructing an overdetermined equation set and solving an optimal fault position, so that the cable line fault positioning of the ring main unit is realized.

The invention relates to a method for calibrating an ultrasonic flowmeter, which is coupled to a pipe (1), for measuring a flow velocity or a volumetric flow rate of a fluid by means of two ultrasonic transducers (2, 3) spaced apart from one another, wherein the main directions of the ultrasonic transducers (2, 3) are oriented at an angle to one another in a symmetrical V shape. The aim of the invention is to provide an improved method which allows the ultrasonic flowmeter to be installed on a pipe with minimal effort, even by untrained personnel, without the accuracy of the measurement being impaired. For this purpose, the invention proposes the following steps: - ascertaining the propagation speed of an ultrasonic signal propagating through the pipe wall as a surface wave; - ascertaining the wall thickness of the pipe by determining the propagation time of an ultrasonic signal through the pipe wall; - ascertaining the inner diameter of the pipe by deriving it from the value of the adjusted angle and the distance of the ultrasonic transducers, - adjusting the angle to the ascertained pipe geometry by means of at least one motorized actuating drive (5) which sets the angle and an electronic calibration device (6) which interacts with the actuating drive (5).

The invention discloses an ultrasonic stress-induced ice layer breaking deicing method, system and device for an insulator, and the method comprises the steps: sequentially transmitting a first frequency detection signal and a second frequency detection signal through an ultrasonic transmitting unit, collecting a reflection signal, and judging whether ice coating exists or not based on the characteristic difference of amplitude attenuation, propagation time difference and phase offset; if icing exists, deicing ultrasonic waves with initial power are transmitted, a power adaptive adjustment model is constructed by using real-time signals reflected by an icing layer, and the deicing power is dynamically optimized in combination with the characteristic change rate; the double-frequency signals are transmitted again at regular intervals, and after re-check reflection signals are collected and subjected to temperature correction, whether ice coating is completely removed or not is judged through characteristic differences; the system comprises an ultrasonic transmitting / receiving module, an icing judgment module and a power adaptive adjustment module. The device comprises a high-frequency ultrasonic generator, an ultrasonic transducer and a microcontroller. The device realizes integration of ultrasonic detection, deicing and effect verification, and is suitable for various insulator winter icing removal scenes.

The invention discloses an ultrasonic guided wave damage ellipse imaging positioning method and equipment for a layer decreasing composite material laminated plate. The method comprises the following steps: S1, acquiring thickness change direction information of the laminated plate and position coordinates of an excitation transducer and a receiving transducer; s2, according to the material characteristic parameters, simulating and calculating the propagation time of ultrasonic guided waves transmitted from an excitation transducer to any point to generate a first theoretical propagation time map, and simulating and calculating the propagation time of the ultrasonic guided waves transmitted from any point to a receiving transducer to generate a second theoretical propagation time map to generate a second theoretical propagation time map; coupling influence of thickness change and material anisotropy on guided wave propagation is considered in the simulation process; s3, transmitting an ultrasonic guided wave signal, and extracting the actual flight time of a damaged wave packet; s4, calculating theoretical total propagation time, and determining a candidate area where damage exists; and S5, on the basis of repeated operation of the multiple groups of transducer pairs, taking a plurality of candidate region intersections to determine a final damage position. The objective of the invention is to solve the positioning error problem caused by the structural characteristics of a laminated plate in a traditional algorithm, and to realize more accurate damage detection and positioning.

The invention discloses a vibration test and state monitoring method and system for an in-operation high-voltage circuit breaker, and the method comprises the steps: carrying out the energy propagation time sequence test of a multi-measurement-point vibration signal, constructing an energy flow direction topological graph, and precisely positioning a vibration source region through energy ratio analysis and path backtracking; acquiring a response time constant by adopting an impact response attenuation test, and converting a vibration source into a fault space positioning coordinate through space grid division and rate matching; a frequency-space mapping relation is established based on a fault position, and vibration characteristics are comprehensively described through peak frequency time sequence tracking and nonlinear component identification such as frequency multiplication, modulation and transient state; performing dispersion analysis on the continuous action impact peak value to form an action consistency deviation, and fusing a nonlinear feature set to quantitatively evaluate the mechanical degradation degree; the grading test density is generated according to the degradation state, the time period test unit is determined, the state grading test benchmark is established to realize mechanical state grade judgment, and the equipment operation reliability and the monitoring efficiency are improved.

The invention discloses a hearth flue gas velocity field measurement method and system based on a multi-layer sonic sensor, and the method comprises the steps: obtaining the sound wave propagation time when a sound wave reaches other sonic sensors after the sound wave is transmitted each time according to the multi-layer sonic sensor; different two-dimensional plane temperature fields are formed based on sound wave propagation time obtained by the same-layer sound wave sensors; according to different two-dimensional plane temperature fields, performing estimation by combining a correlation analysis method and a linear interpolation method to obtain three-dimensional hearth temperature field distribution; constructing a solving equation based on the three-dimensional hearth temperature field distribution, the acoustic wave propagation time and propagation path from the lower acoustic wave sensor to the upper acoustic wave sensor, and a preset flue gas velocity field; and solving the solving equation, outputting unknown parameters in the flue gas velocity field, and reconstructing full-field velocity distribution according to a preset flue gas velocity field formula. According to the method, no hardware cost is increased, the velocity field in the vertical direction of the hearth smoke is accurately measured, and key data support is provided for combustion optimization and intelligent monitoring of a power plant.

The invention discloses an uncalibrated stress measurement method and device based on ultrasonic longitudinal wave and incremental deformation mechanics, and relates to the technical field of ultrasonic nondestructive testing, and the method comprises the steps: obtaining an ultrasonic longitudinal wave time domain signal at a detection point of a to-be-detected test piece and the thickness of the to-be-detected test piece; determining the propagation time of the longitudinal wave in the test piece to be detected based on the ultrasonic longitudinal wave time domain signal; based on the thickness of the to-be-detected test piece and the propagation time, determining the propagation speed of the ultrasonic longitudinal wave in the to-be-detected test piece; and determining a stress value at the detection point of the test piece to be detected according to the propagation velocity. According to the invention, the problem of measuring the high-order elastic constant of the material can be avoided, and the dependence of a stress measurement result on a calibration result is avoided.

A system and corresponding method perform underwater distance determination. The system comprises a hydrophone unit (HU) located at a reference point, a first sensor module (SM), and a second SM, each located underwater. The first SM sends a first sensor-to-hydrophone data signal and a first sensor-to-hydrophone synchronization signal to the HU and sends a first inter-sensor synchronization signal to the second SM. The second SM sends, responsive to receipt of the first inter-sensor synchronization signal from the first SM, a second inter-sensor synchronization signal to the first SM. The second SM sends a second sensor-to-hydrophone data signal to the HU. The first SM measures a time value representing a total travel time of the first inter-sensor synchronization signal from the first SM and second inter-sensor synchronization signal from the second SM and calculates a distance between the first SM and second SM based on the time value measured.

The invention relates to the technical field of industrial process control and fluid dynamic measurement, and discloses a high-precision liquid flow detection method based on a sensor. The method comprises the following steps: arranging a sensor, initializing a measurement section, receiving an ultrasonic signal, extracting a phase difference updated along with time, executing two-point temperature calibration, converting liquid temperature and correcting sound velocity, and obtaining static propagation time delay and a theoretical phase; constructing a net phase difference, inverting an axial instantaneous flow velocity according to a propagation difference, and applying non-negative and upper bound constraints; collecting pressure fluctuation to estimate a turbulence equivalent speed and superposing the turbulence equivalent speed with the main speed; calculating the volume flow according to the cross section area and accumulating the volume; phase anomaly, temperature rate and pressure peak detection is carried out, and substitution, recalculation and interpolation are adopted respectively; and counting and normalizing the maximum values of the speed and the flow, and outputting the speed, the flow, the accumulated volume and a normalized curve.

The invention aims to provide a vertical shaft heading machine attitude determination method and system, and belongs to the field of underground engineering monitoring. The method comprises the following steps: establishing a fixed coordinate system and a carrier coordinate system, acquiring propagation time by using a well wall ultrasonic transmitter and a platform receiver, and resolving absolute coordinates of the receiver and absolute attitude of a platform based on spatial spherical intersection; meanwhile, a gyroscope and an accelerometer are used for collecting angular velocity and specific force information, and high-frequency and low-frequency predicted attitudes are calculated. And combining the absolute attitude with the predicted attitude through a fusion algorithm to obtain an optimal attitude angle, and constructing a conversion matrix to process specific force information so as to solve an optimal position deviation. The advantages of high penetrability of ultrasonic waves and continuity of inertial navigation are utilized, the problem that laser guidance is prone to failure in the dust and muddy water environment is solved, and high-precision and anti-interference real-time monitoring of the posture of the vertical shaft heading machine is achieved.

The invention provides a die head lip opening online measurement method, which comprises the following steps of: pre-acquiring propagation velocities of ultrasonic waves in melts at different temperatures through an experiment, and fitting a relation curve between the propagation velocity v2 of the ultrasonic waves in the melts and the temperature T; the temperature T of the melt flowing out of the lip is collected in real time; according to the relation curve, the propagation velocity v2 of the ultrasonic wave corresponding to the current temperature T in the melt is obtained; the ultrasonic transmitting probe is controlled to transmit ultrasonic waves, and the ultrasonic waves sequentially pass through the first wall, the melt and the second wall and are received by the receiving probe; measuring the total propagation time t of the ultrasonic waves transmitted from the ultrasonic transmitting probe to the receiving probe; and calculating the width h of the lip according to a formula. According to the invention, on-line, real-time and high-precision measurement of the opening degree of the lip can be realized.

This application belongs to the field of meteorological monitoring technology and discloses a three-dimensional orthogonal ultrasonic anemometer and wind measurement method based on the dual-mode time difference method. The anemometer includes: three sets of ultrasonic probes, each set containing two through-beam ultrasonic probes, arranged along the X-axis, Y-axis and Z-axis directions respectively; an ultrasonic mounting base for fixing the three sets of ultrasonic probes, with the backward extension lines of the tail ends of the probes in the X-axis and Y-axis directions intersecting at the center of the mounting base, and the probe in the Z-axis direction located above the symmetrical center line of the plane formed by the X-axis probe and the Y-axis; a conditioning circuit module installed inside the ultrasonic mounting base and electrically connected to the three sets of ultrasonic probes; wherein, the signal conditioning and processing circuit is configured to: calculate a first wind speed value and a second wind speed value based on the threshold time difference method and the median time difference method respectively for the propagation time; output the second wind speed value in response to the determination of low wind speed conditions; and output the first wind speed value in response to the determination of high wind speed conditions.

The invention relates to the technical field of ultrasonic thickness measurement, in particular to a thickness measurement method, an ultrasonic thickness gauge and a storage medium, and the method comprises the steps: sequentially transmitting at least two kinds of ultrasonic waves at a designated position of a to-be-detected object through an ultrasonic generation circuit of the ultrasonic thickness gauge; determining the propagation time of each ultrasonic wave in the to-be-detected object; based on the propagation time of each ultrasonic wave in the to-be-detected object, determining a propagation time difference value corresponding to every two adjacent ultrasonic waves with adjacent signal intensities; determining a target ultrasonic wave according to the size relationship between each propagation time difference and a preset time threshold; and determining the thickness of the to-be-detected object according to the propagation time corresponding to the target ultrasonic wave, thereby improving the accuracy of the measured thickness, and solving the problem that the thickness of the to-be-detected object cannot be measured because the signal intensity of the transmitted ultrasonic wave is too weak. And the problem that the measured thickness is not accurate due to the fact that the signal intensity of the emitted ultrasonic waves is too high is solved.

The application discloses a signal interference strategy generation method and device based on deep learning, and a medium, and relates to the technical field of signal interference. The method comprises the following steps: calculating initial path rain attenuation values corresponding to reference level sampling data and real-time level sampling data; filtering a wet antenna attenuation component of the real-time level sampling data through digital filtering based on the initial path rain attenuation values, and determining pure path rain attenuation values of each communication link; inverting the pure path rain attenuation values to obtain path average rain intensities corresponding to each communication link; performing spatial interpolation optimization on a preset interference area to determine a two-dimensional rainfall intensity distribution map; calculating signal propagation time delay of an interference target ray track to obtain interference target corrected coordinates; and determining an interference strategy corresponding to the interference target through link interference parameter calculation and interference window prediction. The application solves the technical problem that the signal interference strategy in the prior art cannot meet the dynamic requirements of an interference signal link in a rainfall environment.

The invention relates to the technical field of rotating machinery fault monitoring, and discloses a method and system for monitoring a torsional vibration fault of a shaft system of a steam turbine generator unit, and the method comprises the steps: obtaining a single-point torsional vibration signal, and converting the single-point torsional vibration signal into an angular domain sequence; extracting a narrow-band modulation component of a specific order band and calculating a torsional vibration logarithmic response spectrum; performing inverse transformation on the logarithmic spectrum to obtain cepstrum data reflecting the periodicity of the shafting structure; delimiting a structure reflection propagation time delay interval according to the geometric distance from the sealing end to the rigid coupling and the material wave velocity; identifying a sealing-coupling boundary reflection peak value and a series structure in the interval, and constructing a series enhancement index; reversely deducing an equivalent reflection intensity and an equivalent structure distance, and generating a health index; and finally, mapping the health index into a binarization result through a step function, and outputting normal or abnormal judgment for the sealed end. According to the invention, the high-sensitivity and deterministic monitoring of the local abnormity of the sealing end is realized by using the echo structure information.

A method for operating an ultrasonic fluid meter, preferably an ultrasonic water meter, in a fluid line network, at a measuring rate with one measuring interval, includes generating an ultrasonic signal at specific time points by an ultrasonic converter, the ultrasonic signal passing through a measuring section, and the fluid flow volume being ascertained by an electronic analysis unit based on propagation time and / or a propagation time difference of the ultrasonic signal. The hydraulic force exerted onto the ultrasonic converter by a flow event via the fluid or a change in the hydraulic force is detected by the ultrasonic converter and evaluated in the electronic analysis unit. As a result, the measuring rate is adaptively modified to ascertain the flow volume of fluid and / or the flow volume ascertained over a measuring interval is corrected based on the temporal position of the flow event relative to the measuring interval.

The invention discloses an equal-length matching optimization method for differential pair transmission paths of a high-speed printed circuit board, and belongs to the technical field of signal integrity modeling and simulation. Comprising the following steps: constructing a multi-conductor transmission line model containing a reference conductor, extracting a parameter matrix per unit length, judging the uniformity and symmetry of a structure, and introducing a local modal substrate and a continuous modal coupling term which change along with space for describing modal conversion caused by gradual change of the structure, the propagation delay inequality of the two signal paths is calculated, a phase calibration operator is constructed, modal conversion and the delay mismatch effect are brought into a unified propagation equation to be solved, the phase calibration operator is applied at a recoupling reference plane to carry out alignment processing on voltage and current, and finally equivalent differential mode impedance is obtained through calculation. According to the method, integrated modeling is carried out by integrating the joint effect of mode conversion and time delay mismatch, and the impedance simulation precision of the difference pair snake-shaped compensation structure recoupling region is remarkably improved.

The invention relates to an ultrasonic measuring unit (1), in particular for use in a vehicle (2), comprising a control unit (3) and an evaluation unit (4), wherein the control unit (3) is designed to control first ultrasonic transducers (11) for transmitting ultrasonic signals and, on the basis of reception signals generated with the aid of second ultrasonic transducers (12), to detect echoes produced owing to signal paths of the ultrasonic signals, and the evaluation unit (4) has a trained AI module (5) and is designed to process the reception signals in order to detect an object (6; 60) causing the echoes, wherein the processing involves at least generating feature vectors (111, 112, 113) on the basis of the reception signals with the aid of the AI module (5), and the control unit (3) or the evaluation unit (4) is configured to determine, on the basis of the reception signals, a signal propagation time or signal propagation distance corresponding to the signal path for the associated echo, and the AI module (5) is designed to determine the feature vectors (111, 112, 113) on the basis of the signal propagation times or the signal propagation distances.

Gas sensor with the following features: a stoker, a recipient, and a space arranged between the heater and the receiver, wherein the heater is designed to generate a thermoacoustic sound wave propagating through the space using an excitation signal, and wherein the receiver is designed to receive the thermoacoustic sound wave that has propagated through the room and to convert it into a received signal that has a time-dependent shift relative to the excitation signal and thus provides information about a gas concentration in the room; and a gas concentration determination circuit designed to determine a phase shift between the received signal and a heater signal, or, based on the received signal, a travel time of the thermoacoustic wave through the room, each of which is a measure of the gas concentration in the room; and a thermal conductivity determination circuit designed to determine the thermal conductivity of the room, which depends on the gas concentration in the room, using the heater signal, where the heater signal is the excitation signal or a temperature signal indicating the temperature of the heater.

The application discloses a steel rail stress measurement system based on electromagnetic ultrasonic orthogonal transverse waves, which comprises an electromagnetic ultrasonic probe and a signal processing unit. The electromagnetic ultrasonic probe is configured as an orthogonal coil group with an axis, and the electromagnetic ultrasonic probe generates eddy current under the excitation of alternating current and simultaneously generates first transverse waves and second transverse waves in the steel rail. The propagation directions of the first transverse waves and the second transverse waves are both vertically downward from the center of the rail head of the steel rail. The vibration direction of the first transverse waves is the length direction of the steel rail, and the vibration direction of the second transverse waves is the width direction of the rail head of the steel rail. The vibration directions of the first transverse waves and the second transverse waves are perpendicular to each other to form an orthogonal relationship. The signal processing unit is used for synchronously receiving echo signals of the first transverse waves and the second transverse waves, calculating the propagation time difference between the first transverse waves in the length vibration direction and the second transverse waves in the width vibration direction, and evaluating the axial stress of the steel rail according to the propagation time difference between the first transverse waves and the second transverse waves.

The invention belongs to the technical field of stress detection, and relates to a nondestructive measurement method and system for residual stress of a basin-type insulator. The method comprises the following steps: acquiring a transverse wave acoustic elastic birefringence coefficient and a dual-frequency longitudinal wave acoustic elastic coefficient of a standard test block made of the same material as an insulator in different uniaxial stress states; obtaining the transverse wave propagation time of the polarization direction of the target point in the annular direction, the transverse wave propagation time of the polarization direction in the radial direction and the dual-frequency longitudinal wave propagation time of the insulator in the state of no external load; and acquiring circumferential residual stress and radial residual stress at the target point according to the transverse wave acoustic elasticity birefringence coefficient, the dual-frequency longitudinal wave acoustic elasticity coefficient, the transverse wave propagation time of which the polarization direction is in the circumferential direction, the transverse wave propagation time of which the polarization direction is in the radial direction and the dual-frequency longitudinal wave propagation time. Nondestructive testing of the residual stress of the epoxy resin part of the basin-type insulator is achieved, and directional analysis and independent measurement of a complex stress field are achieved.

The application discloses an underwater acoustic tomography flow measurement method based on phase difference. The method comprises the following steps: collecting bidirectional propagation acoustic signals of a water area to be measured, and extracting the propagation time and phase change of the bidirectional propagation acoustic signals; establishing the relationship among the phase change of the bidirectional propagation acoustic signals, the propagation time of the bidirectional propagation acoustic signals, the average flow velocity of the water area to be measured and the average sound velocity of the water area to be measured through wave acoustic, and inversely deriving the average flow velocity of the water area to be measured and the average sound velocity of the water area to be measured through the relationship. The purpose of the application is to provide an underwater acoustic tomography flow measurement method based on phase difference, which is more suitable for use in acoustic tomography technology with lower frequency. The uncertainty in flow velocity measurement can be reduced by simultaneously considering the time difference and the phase difference, and the automatic and high-precision flow measurement technology is promoted. The application is suitable for flow velocity measurement of water areas such as river channels, estuaries and bay areas.

The invention relates to a method for accurately detecting and positioning insulation defects of a 35kV fan cable. The method comprises the following steps: step 1, acquiring head end reflection coefficient spectrum data of the 35kV fan cable; 2, designing an analog incident signal and a time-frequency domain signal; 3, converting the reflection coefficient spectrum from a frequency domain to a time domain to obtain a time domain signal of a reflection signal; step 4, calculating the signal propagation time of the cable, and converting a time domain signal of the reflected signal into a space domain signal, thereby completing the detection and positioning of the insulation defect of the 35kV fan cable and the position of the intermediate joint, and obtaining a preliminary detection and positioning result of the insulation defect of the cable; and step 5, identifying the position corresponding to the peak value of the reflected signal, and determining whether the position is the insulation defect of the 35KV fan cable and the specific position of the intermediate joint so as to complete the detection and positioning of the insulation defect of the 35KV fan cable. According to the invention, rapid and accurate positioning of tiny insulation defects of the 35kV fan cable can be realized.

The invention discloses an amplitude detection method for eliminating a multi-beam sounding sonar tunneling effect. The method comprises the following steps: collecting array element data of a receiving array; generating a beam forming amplitude data matrix according to the array element data; calculating a double-domain dynamic gain normalization matrix; calculating a sampling moment index corresponding to the amplitude maximum value of each receiving beam by using the double-domain dynamic gain normalization matrix, and calculating an amplitude detection time gate by using the index; and calculating propagation time: after the amplitude detection time gate is determined, solving the positions of the centroids of the beam forming amplitude data in all the receiving beam time gates by adopting a weighted average time method, and obtaining the propagation time corresponding to all the receiving beams. The improved amplitude detection method based on the double-domain dynamic gain normalization algorithm provided by the invention has the advantages of obvious tunnel effect inhibition, simple algorithm, no need of parameter setting, and convenience for engineering realization and application.