142 results about "Head wave" patented technology

The invention relates to a judging method of an incompactness defect in a node of a concrete structure by detection by an ultrasonic method. On the basis of the traditional method for detecting the concrete defect by the ultrasonic method, besides an acoustic velocity and a head wave amplitude, two variable acoustic parameters, namely a complex frequency difference and a cross-correlation coefficient, are added; each acoustic parameter is processed into an acoustic parameter judging factor and each acoustic parameter judging factor is processed into a normalized comprehensive acoustic parameter judging factor; a position detecting chromatogram is drawn out according to the comprehensive acoustic parameter judging factor; and the position and range of a suspicious defect are determined according to a red area in the chromatogram. By the method, the compactness quality distribution of concrete can be directly and accurately described; errors and judgment loss caused by adoption of a single acoustic parameter for judgment can be avoided or reduced; and the difficulty in final judgment when the judgment result of the single acoustic parameter is inconsistent is also avoided. The judging method can be widely applied to the judgment of the incompactness defect in the node of the concrete structure or other complex structures.

The invention relates to an ultra-high-voltage direct-current transmission line single-end protective method, and belongs to the technical field of high-voltage direct-current transmission system replay protection. The method includes the steps that firstly, a data acquisition device acquires the fault current data in a time window of 5 ms after a fault current travelling wave head wave head reaches, and a 1 model component is solved; then 1 model current which operates normally before fault is subtracted from a 1 model component current signal, the fault current variable quantity is obtained, summation operation is conducted on the fault current variable quantity, and whether the signal comes from the exterior of a rectification side region or from the exterior of a circuit or the exterior of a contravariant side region is judged according to the summation operation; Hilbert-Huang transform is conducted on the fault current signal from the exterior of the circuit or the exterior of the contravariant side region, the instantaneous frequency maximum value of the signal is obtained, the obtained instantaneous frequency maximum value is compared with the preset threshold value to judge whether the circuit or the exterior of the contravariant side region breaks down. By means of the ultra-high-voltage direct-current transmission line single-end protective method, the full-line protection of an ultra-high-voltage direct-current transmission line can be achieved, and the good speed can be guaranteed.

The invention relates to a same-tower double-circuit DC transmission line double end range finding method having wave velocity correction and belongs to the technical field of electric power system protection. The method includes the following steps: firstly acquiring a line rectification side and inversion side voltage fault component, adopting a phase-model transformation matrix to decouple the voltage fault component and resolve an aerial mode fault component voltage traveling wave; calculating the wavelet transform modulus maxima of the aerial mode fault component voltage traveling wave, obtaining the time t"M, t"N corresponding to the first and the second modulus maxima points; earth faults are arranged every 10 km along the whole length of the same-tower double-circuit DC transmission line and resolving the wave velocities of the earth faults, fitting the wave velocities of the earth faults to obtain an aerial mode wave velocity curve, adopting the iterative method to resolve an aerial mode fault voltage wave velocity v; secondly substituting the aerial mode fault voltage wave velocity v and the time t"M and t"N corresponding to the wavelet transform modulus maxima to a fault range finding formula to resolve x; based on the polarity of the front two modulus maxima points of the aerial mode fault component voltage traveling wave at the rectification side M terminal after head wave alignment, it can be determined that the fault point occurs within a half line length from the rectification side M terminal or out of the half line length.

The invention discloses a gas insulated switchgear (GIS) partial discharge calibration method and a system. The method comprises the steps of establishing a calibration data set, and calibrating a preset position of data in the data set in a GIS; measuring an actual waveform oscillation rising time and an actual maximum amplitude of GIS actual partial discharge on the preset position; comparing the actual waveform oscillating rising time and the actual maximum amplitude with the data in the calibration data set, and carrying out calculation, so as to acquire a discharge part and strength. Specifically, the calibration method disclosed by the invention can accurately measure the calibration data set and data of actual partial discharge through a sensor on the preset position, so that defects of arranging two sensors on each GIS interval and serious error of reading head wave initial time are avoided; in later stage, the discharge part and strength are obtained by simple comparison and calculation, which is free from limitation of an atlas database and overcomes shortcomings of the existing ultra high frequency (UHF) method that pattern recognition fails to accurately provide the discharge strength. Therefore, the calibration method disclosed by the invention can accurately and effectively detects discharge part and strength of partial discharge.

The invention discloses an ultrasonic wave head wave phase reversal testing method for the depth of a shallow fracture in the surface of concrete. The method includes the following steps that (1), floating dust and dirt on the surface of a measured object are removed, whether water or steel bars or other foreign bodies exist in the fracture or not is observed, and it is guaranteed that the measured object is dry; (2), ultrasonic wave measuring points are symmetrically arranged in pairs with the measured fracture serving as the center, the measuring points are numbered in pairs, and each measuring distance is the distance between the inner edges of each pair of transducers; (3), ultrasonic wave measuring points are arranged on one side of the measured facture in pairs, the measuring points are numbered in pairs, and each measuring distance is the distance between the inner edges of each pair of transducers; (4), sound and time measurement without fracture crossing is conducted; (5), sound and time measurement with fracture crossing is conducted; (6), in the measurement with fracture crossing, when head wave phase reversal is found in a certain measuring distance, the depth value of the fracture is calculated through measured values of the measuring distance and two adjacent measuring distances. By means of the ultrasonic wave head wave phase reversal testing method, whether ultrasonic waves diffract to the bottom of the fracture or not is judged by observing the head wave phase change, and then the depth of the shallow fracture in the surface of the concrete is accurately detected.

The invention discloses a method for indoor evaluation of the cementing quality of a cement-formation interface by using ultrasonic waves, and belongs to the cement-formation interface field. The method is operated according to the following steps: firstly, a cement-formation interface cementing model is bonded with the surfaces of a transmitting transducer and a receiving transducer of an ultrasonic device, then the head wave amplitude and the sound velocity of the cement-formation interface cementing model are measured by the ultrasonic device, finally the head wave amplitude and the sound velocity of the cement-formation interface cementing model are measured according to the method, and thus change conditions of the cementing quality of the cement-formation interface along with the curing time is determined. The method is adopted for indoor evaluation of the cementing quality of the cement-formation interface, damage on a cement-formation interface sample cannot be caused, and the sample can be used repeatedly, so as to realize determination of change conditions of the cementing quality of the cement-formation interface along with the curing time; and in addition, the method is simple to operate, good in data repeatability, and suitable for use when a lot of experiments are performed in a laboratory.

The invention discloses a method and a device for detecting and locating a head wave of an ultrasonic wave. The method comprises the following steps of: constructing a track array of an ultrasonic signal sequence; carrying out singular value decomposition on the track array to obtain a singular spectrum entropy of the ultrasonic signal sequence; carrying out median filtering on the singular spectrum entropy and removing signal glitches; and carrying out thresholding operation on the singular spectrum entropy subjected to the median filtering, and then judging that the failing edge of the singular spectrum entropy subjected to the thresholding operation is the head wave of the ultrasonic signal sequence. Under the condition that the track array is proper, the drop between the ultrasonic signal sequence and the singular spectrum entropy in a noise region is large, the edge is abrupt, the singular spectrum entropy has very strong robustness to the amplitude value of the ultrasonic signal sequence and cannot change a lot along with the strength of the signal to noise ratio of a certain segment in the ultrasonic signal sequence, therefore, the method for detecting and locating the head wave of the ultrasonic wave has strong capacity of resisting disturbance and can more accurately locate the very weak head wave submerged in noise.

The invention discloses a head wave inhibition blasting construction method based on an electronic digital detonator, and relates to the technical field of tunnel blasting construction. By applying the digital electronic detonator precise delaying hole-by-hole detonating and inter-hole phase dislocation vibration absorption technologies, the vibration speed peak value of a protection object can bereduced by 60%, moreover, the vibration peak value occurs to a first grooving hole, through destructive interference of vibration waves of vibration absorption holes and vibration waves of the firstgrooving hole, the vibration speed peak value of the protection object is further reduced by 30%, accordingly, the vibration speed of a critical structure object is greatly decreased, the supercritical structure object or ultra-shallow buried tunnel blasting construction technology is achieved, and the head wave inhibition blasting construction method has remarkable social benefits and economic value.

The invention discloses a fault location system for a three-terminal transmission line. The fault location system comprises a first detecting device, a second detecting device, a third detecting device, a fourth detecting device and a treatment device, wherein the first detecting device and the second detecting device are located at two endpoints of the main line of the three-terminal transmission line; the third detecting device is arranged at the endpoint, away from the intersection of the main line and a branch line, on the branch line of the three-terminal transmission line; the fourth detecting device is arranged at the end point, close to the intersection of the main line and the branch line, on the branch line of the three-terminal transmission line; the treatment device is in communication connection with the detecting devices and used for determining the faulty line of the head wave polarity of fault traveling waves collected by the third detecting device and the fourth detecting device and performing fault location according to a single line distribution type fault location method. The fault location system has the advantages that the number of the detecting devices is reduced, fault location cost is lowered, reflection wave information needs not to be used, location reliability is increased, and measuring dead zones are avoided. Correspondingly, the invention further provides a fault location method for the three-terminal transmission line, and the effects of the fault location system and the fault location method are identical.

The invention discloses a method and a circuit for treating an echo signal of a low-power ultrasonic flowmeter. The circuit comprises a variable gain amplifying unit, a peak detection unit, a head wave detection unit and a single chip unit. The method for treating the echo signal of the low-power ultrasonic flowmeter, disclosed by the invention, comprises the following steps: utilizing head wave detection to accurately judge if receiving an echo; controlling the peak detection unit to enable and perform echo peak value measurement; comparing an AD value acquired through the peak value detection with a preset voltage value scope; adjusting an amplification factor to guarantee the consistency of the measured echo signal, thereby reducing the influence of different amplification factors on the waveform and reducing the power consumption of the circuit.

The invention discloses a shaft gas cut early-stage active monitoring method based on a low-frequency elastic wave response characteristic. By adopting the method, the gas containing rate of an annulus nearby the upper portion of a drill bit can be monitored the drilling process in real time, gas cut can be found as early as possible, timely warning can be given, monitoring is sensitive and reliable, precious time can be won for ground design and well control operation implementation, and the safety of an oil gas drilling project can be guaranteed. In the drilling process, a drilling fluid flows through an underground monitoring short section through the annulus, the underground monitoring short section transmits pulse signals according to fixed frequency and converts received response signals into electric signals, two attribute values including first arrival time and a peak value of each of head waves of the electric signals are extracted for encoding, whether gas cut occurs or not is judged, if it is determined that the gas cut occurs, gas cut information is sent to a ground control center through an underground wireless signal transmitter.

The invention relates to a rock core sampling method. The rock core sampling method sequentially comprises the following steps of: weighing and measuring rock cores to be screened; measuring each rock core by using ultrasonic waves with different frequencies, and reading time used by the ultrasonic wave permeating the rock core, head wave amplitude after butt joint of probes and head wave amplitude after the rock core is added; combining an error analysis theory to acquire the numeric range of wave impedance of each rock core; preliminarily screening the rock cores with the intersected wave impedance numeric range under different frequencies; further screening the preliminarily screened rock cores by utilizing sound wave attenuation coefficients; and finally screening the rock cores with the intersected attenuation coefficient numeric range under different frequencies. The rock core sampling method is reliable in principle, simple in structure and convenient in operation. By the method, a large number of rock cores with the same properties for a test can be preferably selected with less time and cost; physical properties, such as mass, density and the like, and internal pore space structures of the rock cores can be quantitatively analyzed; and important significance is achieved in a rock core analyzing test.

The invention provides a grouting fullness detection method based on sleeve surface ultrasonic and a grouting fullness detection system based on the sleeve surface ultrasonic. The detection method comprises the following steps: forming an inspection port in a prefabricated component, wherein the inspection port can expose the outer surface of a grouting sleeve; vertically arranging a plurality ofmeasuring points on the outer surface of the grouting sleeve; arranging ultrasonic transducers integrating transmitting and receiving functions at the measuring points; judging the grouting conditioninside the grouting sleeve according to the intensity of head wave signals received by the ultrasonic transducers. According to the detection method, through formation of the inspection port, namely reservation of the inspection port or formation of the inspection port by virtue of removal of a concrete protecting layer outside the grouting sleeve, the accuracy of a detection result is improved.

The invention discloses a testing and analyzing method for intelligent detection on integrity of a foundation piles by using an acoustic transmission method. The testing and analyzing method comprises the following steps: by taking acoustic transmission method detection data files as basis, calculating sound velocity, head wave amplitude, waveform distortion coefficients, frequency distortion coefficients and signal energy, performing acoustic parameter abnormal critical value calculation and abnormal classification, classifying measuring lines according to the classification result, classifying horizontal sections according to the classification of the measuring lines, furthermore, confirming abnormal sections of a pile body to form horizontal section chromatograms, and overlapping the horizontal section chromatograms so as to form three-dimensional chromatograms, namely, pile body defect distribution diagrams. The testing and analyzing method is based on acoustic detection technical principles and engineering detection practical experience, quantitative analysis on sound parameter calculation, judgment, classification, comprehensive analysis, graphic display and the like can be implemented, the workload and the difficulty of artificial analysis in the data analysis process can be reduced, the mal-judgment risk can be reduced, the information content of the detection result is enriched, the abnormal degree and the spatial distribution of the pile body defects can be visibly displayed in the pile body defect distribution diagrams, and the accuracy and the reliability of the detection result are improved.

The invention discloses a low-speed wind tunnel aerial refueling hose-taper sleeve dynamic characteristic test method, which comprises the following steps of: establishing a perspective transformationimaging model of a high-speed camera by utilizing a three-dimensional vision principle by adopting equipment including a refueling hose, a taper sleeve, supporting equipment, mobile equipment, an oilreceiving aircraft model, an oil receiving taper pipe, two high-speed cameras and a PIV system; calibrating the parameter matrix, establishing a mapping relationship between space points and image points, calculating space coordinates of a centroid point of the refueling taper sleeve through data acquired by a high-speed camera, and obtaining a centroid track of the refueling taper sleeve and information of a pitching attitude angle formed by a longitudinal axial vector of a refueling taper sleeve coordinate system and a horizontal plane; and carrying out speed field calculation and processing on data collected by the PIV system to obtain a head wave effect in the butt joint process of the refueling taper sleeve and the oil receiving taper pipe and a speed cloud picture of the whip throwing phenomenon. According to the method, the dynamic characteristics of the aerial refueling hose-taper sleeve are accurately simulated, and the accuracy of a test result is improved.

The invention discloses a molding device of a corrugated plate, wherein a lower molding roller is arranged on a frame, an upper molding roller is arranged on a regulation slide carriage, the regulation slide carriage is connected with a lifting mechanism simultaneously, and the upper molding roller and the lower molding roller are driven in reverse directions synchronously by a power input unit. The device of the invention has the following characteristics: (1) the corrugation height is preset, thereby automatically regulating the correct position of the upper molding roller through the lifting mechanism; (2) the upper molding roller and the lower molding roller are driven synchronously through the power input unit, thereby avoiding the offset of the center of the waved arc when molding the corrugated plate and keeping the uniformity of relative position of each corrugation; (3) the steel plates are conveyed by a delivery roller, and the delivery roller and the molding roller are in synchronous coordination relation, thereby ensuring the uniformity of each molding position of the steel plates and realizing the consistency of the plate head wave shape of the corrugated plate; and (4) only 3 to 4 rollers are involved in the molding simultaneously during the molding of the steel plate, and the molding force is relatively small, thereby simplifying the mechanism and reducing the cost.

The invention discloses a zero-loss deep current-limiting protection device based on first-wave breaking technology, which includes a protection device body and high-speed switches distributed inside the protection device body; device, display and control, indicator light, button, analog plate, observation window and nameplate, and the inner side of the protection device body is provided with a through-bus bar, a supporting insulator, a quick switch, a first current transformer, a second current transformer and two contact boxes , wherein the through busbar is connected to one of the contact boxes through the supporting insulator, the other contact box is connected to the second current transformer through the first current transformer, and the two contact boxes are connected through a fast switch. The invention has fast action speed, strong breaking capacity, good current limiting effect of the current-limiting reactor, no energy loss, no voltage drop, and no leakage magnetic field, long service life, reliable performance, small action dispersion, and no switching on. rebound.

The invention relates to a concrete-structure-quality evaluating method based on ultrasonic CT.The concrete-structure-quality evaluating method includes the steps that on the basis of a traditional method for detecting concrete defects with an ultrasonic method, two quantizable sound parameters of the complex frequency difference and the cross correlation coefficient are added besides the sound speed and the wave amplitude of a head wave, measuring values of the sound parameters are processed into sound parameter judgment factors, the sound parameter judgment factors are processed into a normalized comprehensive sound parameter judgment factor, and the reliability of the judgment factor is evaluated on the basis; a position measuring chromatogram is drawn according to the comprehensive judgment factor, and the position and the range of suspicious defects are determined according to red confluent areas in the chromatogram.According to the concrete-structure-quality evaluating method, as the step of evaluating the judgment result is additionally set, the accuracy of quality evaluation is greatly improved, and construction safety and personal safety are guaranteed.

The invention discloses a while-drilling sound wave well cementation quality evaluation method and a processing device. The while-drilling sound wave well cementation quality evaluation method comprises the steps that 1, while-drilling data are pre-processed, and full-wave train data of array sound waves are obtained; 2, the influence of drill collar waves in the head waves is eliminated; 3, the energy of a head wave is calculated, and the wave energy of a sleeve in a window is calculated according to the length of the window; 4, a head wave array attenuation factor is calculated, and a corresponding array attenuation factor is calculated according to the obtained head wave energy; 5, a cementation index is calculated, and the cementation index is calculated by using a cementation index calculation formula according to a fitting formula of the attenuation factor of the block and the CBL; 6, the well cementation quality is comprehensively evaluated by using a cementation index curve; and 7, whether all the depth points are processed or not is judged, if so, processing is ended, and if not, the steps are repeated until all the depth points are processed. According to the while-drilling sound wave well cementation quality evaluation method, the problems of long time consumption and high cost during well cementation quality evaluation of highly-deviated wells and horizontal wells in cable logging can be solved.

The present invention relates to methods and apparatuses for using head waves to greatly improve microseismic event localization accuracy, particularly in the depth dimension, by analyzing them in addition to direct path arrivals whenever they are observed. Embodiments of the invention also include techniques known as multipath analysis.

The invention discloses a movable large current impact generator, which comprises a power supply, an integrated charging device, an impact generator body, a measurement and acquisition unit, a to-be-tested product and a control unit; the impact generator body comprises an H type distributed main capacitors which are not less than 8 grade, the lowest layer of the impact generator body is set as a first grade; the impact generator body comprises eight main capacitors, four discharge sphere gaps, a charging resistor, a head wave resistance and a tail wave resistance. According to the movable large current impact generator, insulation requirement is ensured, meanwhile, device volume and weight are reduced, transportation and movement are convenient, economy and reliability of field tests areimproved; operation is simple, automatic control of charging, discharging, data acquisition and storage is realized through a computer; safety and reliability are achieved, and safety isolation between different electric potentials is carried out through measures such as isolation transformers and optical fiber transmission.

The invention relates to an integrated six-degree-of-freedom floater wave energy power generation device. The device comprises a support, a cavity for wave incidence is formed in the support, the side, facing waves, of the support is provided with a head wave perforated plate, the side, away from the waves, of the support is provided with a back wave baffle, and the top of the support is provided with a power generation gear assembly. A floater assembly connected with the power generation gear assembly is arranged in the cavity formed by the support. The floater decouples six types of motion modes into single reciprocating linear motion, the structure is simple, convenient and reasonable, electric energy converted from motion of the floater with all degrees of freedom is collected, wave energy can be fully utilized for power generation, and the power generation efficiency is high.

The invention discloses a wrong wave prevention method for an ultrasonic flowmeter and the ultrasonic flowmeter. The method comprises the steps that an initial threshold value is set; according to the initial threshold value, a steady-state sine wave peak value and amplitudes of a plurality of continuous waveforms which exceed the initial threshold value and are before the steady-state sine wave are obtained from the first echo signal, and the amplitudes comprise a head wave and an adjacent waveform after the head wave; according to the steady-state sine wave peak value of the first echo signal and the amplitudes of the plurality of waveforms, calculating to obtain a first preset value; obtaining a second preset value of the second echo signal according to the initial threshold value; obtaining a second threshold value according to the ratio of the second preset value to the first preset value; and obtaining the head wave of the third echo signal according to a second threshold value. The ratio of the first preset value of the first echo signal to the second preset value of the second echo signal is calculated, the initial threshold is adjusted according to the ratio to obtain the second threshold, logic is simple, real-time calculation is facilitated, the influence of wrong waves can be avoided, the influence of interference on a metering result is reduced, and metering precision is improved.

The invention discloses an ultrasonic imaging well measuring method. A rotating probe is connected with an energy converter. The rotating probe drives the energy converter to rotate. In the rotating process of the energy converter, one ultrasonic pulse signal is stimulated to scan an oil well to be measured at 360 degrees, and thus the ultrasonic pulse signal can be broadcast in fluid of the oil well to be measured and merged into the inner wall of a casing pipe of the oil well; the ultrasonic wave train reflected from the external interface and the internal interface of the casing pipe is measured, information of the inner diameter of the casing pipe is obtained according to echo time of the received ultrasonic wave train, the thickness information of the inner wall of the casing pipe isobtained according to the resonance wave frequency of the casing pipe, and acoustic impedance information of ring space is obtained according to the resonance wave head wave scope. By means of one-time well going, quality of cement bonding and the casing pipe is evaluated, the measure period is shortened, and the operation cost is reduced. Accurate judgment can be made to solid phase cement, liquid phase water, uncemented microgaps and gas, and the phase state of the ring space can be known more intuitively. The inner diameter, the outer diameter, the wall thickness and the corrosion situationof the casing pipe can be recognized, and quantitative judgment is made for the corrosion situation of the casing pipe.

The invention belongs to the field of acoustic logging, specifically relates to a method for detecting digital acoustic head waves. The existing method for detecting acoustic head waves is a threshold method which is characterized in that a fixed threshold value Vs is determined by an algorithm or inputted by an operator, therefore, in the method, the determination of the threshold value limits the correctness in detecting the head wave. The method for detecting digital acoustic head waves comprises the following steps: 1) initializing; 2) selecting the Tf and Ts of appropriate wave trains; 3) limiting the time detection range of the head wave of each wave train; 4) calculating the threshold value Vs of the head wave of each wave train; 5) detecting the time T1 of the head wave of each wave train; 6) fitting the time line of the head wave of each wave train by using the least square method, then reversely reasoning the theoretical times of the head waves, and comparing the obtained times; 7) searching samples Td with a threshold value less than the threshold value Vs from the head wave of each wave train; and 8) searching the largest sample as the position of the head wave between T and Td. The acoustic head waves detected by using the method provided by the invention are high in accuracy.

The invention discloses a method and system for eliminating outlier interference of seismic data. The method comprises the steps of picking up an outlier trace based on original shot gather data, anddetermining the apparent velocity at the top of a head wave band and the time window length of the head wave band; calculating the top time of a head wave band time window corresponding to each seismic trace, determining the head wave band time window corresponding to each seismic trace, and obtaining a head wave horizontal time window and a reflected wave horizontal time window corresponding to each seismic trace; calculating the maximum value of the absolute amplitude of the outlier trace and the average of the maximum absolute amplitudes of adjacent normal traces within the time window, calculating an amplitude correction factor, obtaining an amplitude correction value, and obtaining an outlier trace after the amplitude correction; and carrying out spatial median filtering to obtain a median filtering value, replacing the amplitude correction value with the median filtering value to obtain a replacement seismic trace, and obtaining seismic traces with the outlier interference beingeliminated. The method can effectively eliminate the influence of outlier interference without transforming the normal seismic traces, thereby avoiding data distortion of the normal seismic traces.

The invention provides a water plane wave water surface take-off and landing water-gas two-phase flow numerical simulation method, which is based on an integral dynamic grid technology and a speed inlet wave making technology, and improves a grid division strategy and a flow field initialization method, thereby realizing unsteady flow field calculation of water plane wave water surface take-off and landing. In order to research the problem of wave dampening of a water surface aircraft, according to the method, an initial phase item and an initial balance position item are added in a wave surface equation, a wave velocity field and a pressure field function, so that phase deviation of waves in a computational domain along a propagation direction and vertical deviation of a wave balance position are realized; and therefore, the wave is in contact with the object in an extremely short solving time, and the time of waiting for the head wave by the object is saved. Compared with the conventional dynamic grid method, the method has the advantages that the grid quantity can be reduced, the grid utilization rate can be improved, and higher calculation speed can be obtained while the solving precision is ensured.

The invention provides an array acoustic logging head wave arrival time determination method and device, and the method comprises the steps: carrying out the local autocorrelation analysis and local standard deviation analysis of the full-wave waveform data of a depth of a pre-designated reference channel, and generating a local autocorrelation attribute channel and a local standard deviation attribute channel; combining the local self-correlation attribute channel and the local standard deviation attribute channel according to a preset weight to obtain a combined attribute channel; calculating the energy ratio of the combined attributes in the front and back time windows at each sampling point in the preset time range on the combined attribute channel, and taking the time corresponding to the sampling point with the maximum energy ratio as the head wave arrival time of the reference channel; and performing cross-correlation analysis on the data in the preset window length at different waveform recording times of the other channels and the data in the preset window length of the reference channel, and taking the waveform recording time corresponding to the maximum value of the correlation coefficient on each channel as the head wave arrival time on the corresponding channel, so that the head wave arrival information is effectively highlighted, the rapid and accurate extraction of the head wave arrival time is realized, and the effect is relatively good under the condition of low signal-to-noise ratio.

The invention discloses a non-contact nondestructive testing method for the strength of water-immersed concrete, and belongs to the technical field of nondestructive testing. For water-immersed concrete structures widely existing in water conservancy, ocean and bridge engineering, through a piezoelectric ceramic probe, by utilizing a water coupling effect, a Rayleigh wave is excited on the surfaceof a concrete workpiece in a transmitting and receiving mode under water; a wave velocity and a head wave peak of a response signal are extracted through Hilbert transform; through a K-means clustering algorithm, a classifier is trained by using a training set sample measured in a laboratory; and the wave velocity and the wave peak actually measured under the water are input into the classifier,and the strength of the tested concrete workpiece is intelligently identified. A new method is provided for nondestructive testing and online monitoring of the underwater concrete structures; a basisis provided for safety evaluation of the underwater concrete structures; and the non-contact nondestructive testing method plays an important role in guaranteeing the structural safety of major infrastructures.

The invention provides a pile body defect detection method. Excitation sources are arranged in soil around piles beside a pile foundation, a sensor arranged on the side wall of the top of the pile foundation is used for detecting transmitted stress wave signals, and according to the position of a head wave gradient inflection point in a time-depth oscillogram, the quality of the pile foundation and the position of a pile body defect in the pile foundation are determined. Head wave time detected by the to-be-detected pile foundation is compared with head wave time of a standard pile foundation,thus, whether the pile foundation has the pile body defect or not can be pre-determined, when the pile foundation does not have the pile body defect, it is not needed to determine the position of thepile body defect through excitation sources at different positions, under the condition of the same detection effect, the detection time can be shortened, and the detection efficiency can be improved.