Stone cultural relic crack detection method based on concrete ultrasonic tomography scanner

Abstract

The invention relates to the technical field of crack detection, in particular to a stone cultural relic crack detection method based on a concrete ultrasonic tomography scanner. The method comprises the following steps: acquiring a crack characteristic value according to the quantity and signal intensity difference of ultrasonic signals received by a probe of each fault at each moment and the fluctuation degree of the sound path length of the ultrasonic signals; according to the signal intensity of the ultrasonic signal received by each probe at each moment, the difference of the round-trip time and the crack characteristic value, the crack possibility degree is obtained; the crack possibility degree is adjusted according to the fluctuation degree of the crack possibility degree of the adjacent probe of each probe, and the corrected crack possibility degree is obtained; and obtaining the crack probability according to the difference of the crack correction possibility degrees of each probe and the adjacent probe in the historical analysis time period of each moment, and then carrying out crack detection on the stone cultural relics. The method considers the interference signal generated by the cultural relic internal crack, and improves the detection accuracy of the cultural relic internal crack.

Description

Technical Field

[0001] The present invention relates to the technical field of crack detection, and particularly to a method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner. Background Art

[0002] Stone cultural relics often have extremely high historical, cultural, and artistic values. Ultrasonic tomography detection is a non-contact and non-destructive advanced technology. When using ultrasonic tomography technology to detect cracks in stone cultural relics, there is no need to contact the surface of the cultural relics, avoiding risks such as surface scratches, structural disturbances, or chemical contaminations of the stone cultural relics. At the same time, no physical or chemical changes are introduced during the detection process, supporting multiple and long-term repeated detections of the same cultural relic.

[0003] Ultrasonic waves propagate in a straight line within the stone cultural relics, but the internal cracks of the cultural relics will cause medium changes, and the ultrasonic waves will diffract around the cracks for propagation, resulting in a delay in the reception time of the ultrasonic waves. Existing methods detect cracks in stone cultural relics based on the propagation time of ultrasonic signals. However, due to scattering and reflection of ultrasonic waves in the cracks inside the cultural relics, a large number of interference signals will appear inside, and there will also be a large number of interference signals in the received ultrasonic waves. It is easy to misjudge the cracks or the signals do not show the cracks significantly, reducing the accuracy of crack detection inside the cultural relics. Summary of the Invention

[0004] In order to solve the technical problem that the reflection and scattering of ultrasonic waves at the crack position lead to inaccurate detection of cracks inside the cultural relics, the purpose of the present invention is to provide a method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner. The specific technical solutions adopted are as follows: The present invention proposes a method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner, and the method includes: Obtain the ultrasonic signals received by the probe of each tomography when the concrete ultrasonic tomography scanner performs tomography scanning on the stone cultural relics at each moment during the acquisition period, as well as the signal intensity, round-trip time, and sound path length of the ultrasonic signals; Obtain the crack characteristic value of the corresponding probe at each moment according to the quantity and signal intensity difference of the ultrasonic signals received by the probe of each tomography at each moment, and the fluctuation degree of the sound path length of the ultrasonic signals; Obtain the crack possibility of each probe at each moment according to the signal intensity and round-trip time difference of the ultrasonic signals received by each probe at each moment, and the crack characteristic value; and adjust the crack possibility of each probe at each moment by using the difference in the crack possibility between each probe and its adjacent probe to obtain the corrected crack possibility; Based on the similarity of the crack probability correction between each probe and its adjacent probes during the historical analysis period at each moment, and the difference in crack characteristics between adjacent moments during the historical analysis period of each probe, obtain the crack probability of each probe at each moment; perform crack detection on the stone cultural relics according to the crack probabilities of the probes on the same fault plane.

[0005] Further, the obtaining of the crack characteristic values of the corresponding probes at each moment includes: Obtain the signal intensity of the ultrasonic wave emitted during the tomographic scanning by the scanner, denoted as the standard intensity; take the difference between the standard intensity and the signal intensity of the ultrasonic signal as the ultrasonic loss. Select the ultrasonic signal corresponding to the minimum round-trip time from the ultrasonic signals received by the probe at each moment as the direct wave. According to the ultrasonic losses of the direct wave and the remaining ultrasonic signals received by the probe at each moment, and the number of ultrasonic signals, obtain the abnormal loss degree of the probe at each moment. Denote the sound path length corresponding to the direct wave as the ideal path length; perform normalization processing on the standard deviation of the absolute values of the differences between the sound path lengths of all the ultrasonic signals received by the probe at each moment and the ideal path length, to obtain the distance fluctuation degree of the probe at each moment. From the abnormal loss degree and the distance fluctuation degree, form the characteristic vector of the probe at each moment; take the modulus length of the characteristic vector as the crack characteristic value of the probe at each moment.

[0006] Further, the obtaining of the crack probability of each probe at each moment includes: According to the signal intensity, the difference in round-trip time, and the crack characteristic value of the ultrasonic signals received by the probe at each moment, obtain the initial probability of the probe at each moment. Count the proportion of the number of ultrasonic signals with each signal intensity in all the ultrasonic signals received by the probe at each moment, denoted as the signal volume ratio of each signal intensity, calculate the absolute value of the difference between every two signal volume ratios corresponding to the signal intensities, and take the average of all the absolute values of the differences to obtain the intensity difference. According to the intensity difference and the initial probability, obtain the crack probability of the probe at each moment.

[0007] Further, the obtaining of the initial probability of the probe at each moment includes: Select the ultrasonic signal corresponding to the minimum signal intensity from the ultrasonic signals received by the probe at each moment as the strongest intensity signal. Calculate the absolute value of the difference in round-trip time and the absolute value of the difference in signal intensity between the direct wave and the strongest intensity signal received by the probe at each moment respectively, and take the product of the two absolute values of the differences as the signal difference degree. Based on the signal difference degree and the crack eigenvalue, obtain the initial possibility of the probe at each moment.

[0008] Further, the method for obtaining the corrected crack possibility includes: Normalize the sum of the differences in the crack possibilities of each probe and its adjacent probes at each moment, and use the processing result to weight the crack possibility of each probe at each moment to obtain the corrected crack possibility of each probe at each moment.

[0009] Further, the obtaining of the crack probability of each probe at each moment includes: Calculate the cosine similarity of the eigenvectors between every two adjacent moments within the historical analysis period of each probe at each moment, and perform a negative correlation mapping on the sum of all cosine similarities to obtain the signal disorder degree of each probe at each moment; Obtain the neighborhood signal similarity of each probe at each moment according to the difference in the corrected crack possibilities of each probe and its adjacent probes at all moments within the historical analysis period at each moment; Obtain the crack probability of each probe at each moment according to the mean value of the corrected crack possibilities of the crack sequence of each probe at each moment, the signal disorder degree, and the neighborhood signal similarity.

[0010] Further, the crack detection of the stone cultural relic according to the crack probability of the probes on the same fault plane includes: Judge whether the crack probabilities of all probes of each fault at all moments within the acquisition period meet the preset conditions. If so, there is no crack in each fault; if not, there is a crack in each fault; The preset conditions are: the crack probabilities of all probes of each fault at all moments within the acquisition period are all less than the preset crack threshold, and the range of all crack probabilities is less than the preset fluctuation threshold.

[0011] Further, the obtaining of the neighborhood signal similarity of each probe at each moment includes: Arrange the corrected crack possibilities of each probe at all moments within the historical analysis period at each moment in time sequence to obtain the crack sequence of each probe at each moment; calculate the sum of the cosine similarities of the crack sequences of each probe and its adjacent probes at each moment as the neighborhood signal similarity of each probe at each moment.

[0012] Further, the mean value of the corrected crack possibilities of the crack sequence of each probe at each moment, the signal disorder degree, and the neighborhood signal similarity are all positively correlated with the crack probability.

[0013] Further, the preset crack threshold is 0.87.

[0014] The present invention has the following beneficial effects: In the embodiment of the present invention, by analyzing the signal characteristics of possible cracks in the ultrasonic signals of each probe at each moment, the crack characteristic values representing the crack characteristics of stone cultural relics are obtained; at the same time, the crack signal characteristics of each probe are compared with those of adjacent probes to verify the accuracy of the crack characteristic values of each probe, and based on the fluctuation degree of the crack possibility of adjacent probes of each probe, the crack possibility of each probe at each moment is corrected to obtain the corrected crack possibility, so as to improve the accuracy of ultrasonic analysis for detecting cracks in stone cultural relics; the instability of crack characteristics in time series and the signal changes at the positions of adjacent probes are used to analyze the crack probability of each probe at each moment, and crack detection of stone cultural relics is realized based on the crack probability, which improves the accuracy of crack detection in stone cultural relics and the accuracy rate of crack detection in stone cultural relics. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for description in the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a flowchart of the steps of a method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner provided by an embodiment of the present invention; Figure 2 It is a flowchart of a method for obtaining the crack possibility provided by an embodiment of the present invention; Figure 3 It is a flowchart of a method for obtaining the crack probability provided by an embodiment of the present invention; Figure 4 It is a schematic diagram of a computer device of a device for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following specifically describes, in conjunction with the accompanying drawings and preferred embodiments, the method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner proposed according to the present invention, including its specific implementation manner, structure, features and effects, as follows. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0019] The following specifically describes, in conjunction with the accompanying drawings, the specific solution of the method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner provided by the present invention.

[0020] Example 1:

[0021] The present invention proposes a method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner. Please refer to Figure 1 , which shows the flowchart of the steps of a method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner provided by an embodiment of the present invention. The method includes: Step S1: When the concrete ultrasonic tomography scanner performs tomographic scanning on the stone cultural relics, obtain the ultrasonic signals received by the probe for scanning each tomogram at each moment during the acquisition period, as well as the signal intensity, round-trip time and sound path length of the ultrasonic signals.

[0022] Use the concrete ultrasonic tomography scanner to perform tomographic scanning on the stone cultural relics. Take multiple dry-point contact sensors of the scanner as probes, and each probe has an independent pulse emission and reception channel. Control the probes of the scanner to sequentially emit ultrasonic waves to each tomogram of the stone cultural relics. The probes collect ultrasonic signals at a sampling frequency of 10 MHz, and obtain the ultrasonic signals received by the probe for scanning each tomogram during the time period between each moment and the previous adjacent moment during the acquisition period, which is recorded as the ultrasonic signals received by the probe for scanning each tomogram at each moment. At the same time, obtain the signal intensity, round-trip time and sound path length of the ultrasonic signals. The acquisition period of each probe is determined according to the theoretical time delay of sound wave propagation of the corresponding tomogram.

[0023] It should be noted that the spatial arrangement of the probes is a planar array. The signal intensity refers to the maximum amplitude of the ultrasonic signal, and the signal intensity of the ultrasonic waves emitted by the probes scanning all tomograms is the same; the round-trip time is the time from sending to receiving the ultrasonic signal; the acoustic path length refers to the actual propagation path length of the ultrasonic wave in the medium, which is equal to the product of the propagation speed of the ultrasonic wave in the stone cultural relics and the round-trip time. Since there are interference signals such as scattering and refraction during the ultrasonic detection process, the probes may receive multiple ultrasonic signals at each moment.

[0024] In one implementation of the embodiment of the present invention, the tomogram step size is set to 5 cm.

[0025] Step S2: Obtain the crack characteristic value of the corresponding probe at each moment according to the number and signal intensity difference of the ultrasonic signals received by the probes of each tomogram at each moment, and the fluctuation degree of the acoustic path length of the ultrasonic signals.

[0026] During the detection of cracks in stone cultural relics, severe reflection and scattering will occur at the crack position, increasing the number of signals received by the probes. The energy of the signals after reflection and scattering is absorbed, resulting in a significant reduction in the energy of the ultrasonic signals. Moreover, these signals reach the probes after multiple reflections and scatterings, further exacerbating the energy difference of the ultrasonic signals. If there are no cracks, the ultrasonic waves basically propagate in a straight line, and the reflection and scattering phenomena are not obvious. Although this phenomenon cannot be completely avoided, the number of signals received by the probes decreases and the signal intensities are close. Considering that the crack detection result is affected by the angle of the ultrasonic waves emitted by the probes, that is, the scanning angle, normal ultrasonic signals will also diffract after passing through the stone cultural relics. However, if the crack depth is relatively shallow or the scanning direction is almost parallel to the crack direction, it will also cause the ultrasonic signals received by the probes to maintain a high degree of consistency, that is, the signal intensities are similar. However, there are still significant differences in the lengths of the propagation paths of the ultrasonic signals after multiple reflections and scatterings, that is, the fluctuation degree of the acoustic path length of the ultrasonic signals detected for cracks is relatively large. Therefore, by combining the number and intensity difference of the ultrasonic signals received by the probes at each moment, and the fluctuation degree of the acoustic path length of the ultrasonic signals, analyze the crack characteristics of each tomogram of the stone cultural relics to obtain the crack characteristic value.

[0027] Step S3: Obtain the crack probability of each probe at each moment according to the signal intensity and the difference in round-trip time of the ultrasonic signals received by each probe at each moment, and the crack characteristic value; and use the difference in the crack probability between each probe and its adjacent probes to adjust the crack probability of each probe at each moment to obtain the corrected crack probability.

[0028] Reflection, scattering, etc. will absorb the ultrasonic energy at the crack, resulting in a significant reduction in the acoustic energy reaching the probe. However, the signal energy representing the real crack through diffraction is relatively high, with less scattering and reflection. At the same time, the sound wave is affected by random factors such as reflection and scattering at the crack, resulting in inconsistent signal intensities of the ultrasonic signals received by the probe at each moment. In contrast, the signal intensities of the ultrasonic signals received by the probe without passing through the crack at each moment are highly consistent. Therefore, by obtaining the crack probability based on the differences in signal intensities, round-trip times of different ultrasonic signals received by the probe at each moment, and crack characteristic values, the accuracy of ultrasonic analysis for detecting cracks in stone cultural relics can be improved.

[0029] Stone cultural relics with cracks will have different ultrasonic signal manifestations at different monitoring positions. Specifically, strong reflection occurs at the crack edge, resulting in a relatively high signal intensity at the edge, showing the phenomenon of ultrasonic edge enhancement. When there are cracks, the crack characteristics of the ultrasonic signals received by each probe are greater than those of adjacent probes. Therefore, by using the fluctuation degree of the crack probabilities of the adjacent probes of each probe, the crack probability of each probe at each moment is adjusted to obtain the corrected crack probability.

[0030] It should be noted that in one implementation manner of the embodiment of the present invention, for all probes of each fault, any one probe is selected as the target probe, and the other probes within the region formed by taking one-tenth of the length of the minimum circumscribed cuboid of the stone cultural relic with the target probe as the center as the radius are used as the adjacent probes in the target region.

[0031] Step S4: Obtain the crack probability of each probe at each moment according to the similarity of the corrected crack probabilities of each probe and its adjacent probes during the historical analysis period at each moment, and the crack characteristic differences between adjacent moments during the historical analysis period of each probe at each moment; perform crack detection on the stone cultural relic according to the crack probabilities of the probes on the same fault plane.

[0032] The scanning angle of the stone cultural relics and the angle of the crack will also affect the ultrasonic signal analysis, making the ultrasonic signals manifested as fissures have high similarity in crack characteristics with the ultrasonic signals of adjacent probes, resulting in the corrected crack probability being insufficient to represent the true fissure defect. If there is a fissure, there are reflections and scatterings of different paths in the received signal at each moment, and there are differences in the ultrasonic signals at the same position at different moments. If there is no fissure defect, there are fewer reflections and scatterings during the propagation of ultrasonic waves, so the ultrasonic signals at the same position at different moments are stable, that is, the crack characteristics of the ultrasonic signals are relatively close. At the same time, if the difference in the crack characteristics of the ultrasonic signals received by each probe and its adjacent probes within a local time period is greater, that is, the similarity is smaller, the probability of a crack appearing at the position of the probe is greater. Therefore, by comprehensively considering the similarity of the corrected crack probability between each probe and its adjacent probes within the historical analysis period at each moment, and the difference in crack characteristics between adjacent moments within the historical analysis period of each probe at each moment, it is analyzed whether there is a fissure in each probe to obtain the crack probability. According to the crack probability of the probes on the same fault plane, it is determined whether there is a crack in each fault of the stone cultural relics. After the tomographic scanning of the entire stone cultural relic is completed: visualize the two-dimensional tomographic scanning images of each fault, and reconstruct them through the three-dimensional imaging software idealViwer3D to visualize the fissures inside the stone cultural relics.

[0033] In an implementation manner of the embodiment of the present invention, each moment is located at the last moment within its historical analysis period, and the total number of moments within the historical analysis period is set to 4, and the implementer can set it according to specific situations.

[0034] Preferably, in some possible implementation manners of the embodiment of the present invention, the method for obtaining the crack characteristic value includes: obtaining the signal intensity of the ultrasonic wave emitted during the tomographic scanning by the scanner, denoted as the standard intensity; taking the difference between the standard intensity and the signal intensity of the ultrasonic signal as the ultrasonic loss; selecting the ultrasonic signal corresponding to the minimum round-trip time from the ultrasonic signals received by the probe at each moment as the direct wave; obtaining the abnormal loss degree of the probe at each moment according to the ultrasonic loss between the direct wave received by the probe at each moment and the remaining ultrasonic signals, and the number of ultrasonic signals; denoting the sound path length corresponding to the direct wave as the ideal path length; normalizing the standard deviation of the absolute value of the difference between the sound path lengths of all the ultrasonic signals received by the probe at each moment and the ideal path length to obtain the distance fluctuation degree of the probe at each moment; forming a feature vector of the probe at each moment from the abnormal loss degree and the distance fluctuation degree; taking the modulus length of the feature vector as the crack characteristic value of the probe at each moment.

[0035] It should be noted that the propagation path of the sound wave propagating through the diffraction crack increases, resulting in an increase in the round-trip time. The direct wave represents the signal of the real crack, and the remaining ultrasonic signals can be regarded as interference signals after reflection and scattering. Ultrasonic loss reflects the acoustic energy loss during the ultrasonic propagation process. The crack position will cause severe reflection and scattering of the interference signals, consuming more acoustic energy. Therefore, the signal intensity difference between the direct wave and the interference signals is relatively large. The more abnormal the acoustic energy loss is, the more obvious the crack characteristics at the probe position are. If the number of ultrasonic signals received by the probe at each moment is larger and the acoustic energy consumption of the signals after reflection and scattering is more abnormal, the crack characteristics at the probe position are more obvious. In the embodiment of the present invention, the method for obtaining the abnormal loss degree is as follows: calculate the absolute value of the difference between the mean signal intensity of the ultrasonic signals received by the probe at each moment except the direct wave and the signal intensity of the direct wave, and normalize the product of the absolute value of the difference and the number of ultrasonic signals received by the probe at each moment to obtain the abnormal loss degree of the probe at each moment; the larger the abnormal loss degree is, the more obvious the crack characteristics at the probe position are. It should be noted that in the embodiment of the present invention, the Norm function is used for normalization processing, and other normalization methods such as function transformation and maximum-minimum normalization can also be selected, which are not limited herein.

[0036] The ideal path length is the propagation path length of the direct wave representing the real crack. The standard deviation of the absolute value of the difference between the acoustic path length of the ultrasonic signal received by the probe at each moment and the ideal path length is used to measure the fluctuation degree of the acoustic path length of the ultrasonic signal. If the standard deviation is larger, the length fluctuation of the acoustic wave propagation path is larger, and the crack characteristics at the probe position are more obvious. Therefore, both the abnormal loss degree and the distance fluctuation degree can reflect the crack characteristics at the probe position, and the two can form a feature vector presenting the crack characteristics. The longer the modulus length of the feature vector is, the more obvious the crack characteristics at the probe position are.

[0037] Preferably, in some possible implementation manners of the embodiment of the present invention, for the method for obtaining the crack possibility, please refer to Figure 2 , which shows a flowchart of a method for obtaining a crack possibility provided by an embodiment of the present invention. The method includes: Step S310: Obtain the initial possibility of the probe at each moment according to the signal intensity, the difference in round-trip time, and the crack characteristic value of the ultrasonic signal received by the probe at each moment.

[0038] Preferably, in some possible implementation manners of the embodiments of the present invention, the method for obtaining the initial possibility includes: selecting the ultrasonic signal corresponding to the minimum signal intensity from the ultrasonic signals received by the probe at each moment as the strongest signal; respectively calculating the absolute value of the difference between the round-trip time of the direct wave received by the probe at each moment and the strongest signal, and the absolute value of the difference between the signal intensities, and taking the product of the two absolute values of the differences as the signal difference degree; obtaining the initial possibility of the probe at each moment according to the signal difference degree and the crack characteristic value.

[0039] It should be noted that the sound waves reflected and scattered at the crack position will increase the round-trip time. At the same time, reflection, scattering, etc. will absorb the ultrasonic energy at the crack, resulting in a significant reduction in the ultrasonic energy reaching the probe. However, the signal energy of the signal representing the real crack passing through diffraction is relatively high and the round-trip time is relatively short. Therefore, the greater the difference in the signal energy and round-trip time between the direct wave and the strongest signal, the greater the possibility that there is a crack in the stone cultural relic. If the crack characteristic value is larger, the crack characteristic at the probe position is more obvious, then the possibility of a crack appearing at the probe position is greater. Therefore, both the crack characteristic value and the signal difference degree are positively correlated with the initial possibility. In the embodiments of the present invention, the product of the signal difference degree and the crack characteristic value of the probe at each moment is normalized to obtain the initial possibility. The Norm function is used for normalization processing in the embodiments of the present invention.

[0040] Step S320: Count the proportion of the number of ultrasonic signals with each signal intensity in all the ultrasonic signals received by the probe at each moment, denoted as the signal quantity ratio of each signal intensity, calculate the absolute value of the difference between the signal intensities corresponding to every two signal quantity ratios, and take the average of all the absolute values of the differences to obtain the intensity difference.

[0041] It should be noted that the sound waves are affected by random factors such as reflection and scattering at the crack, resulting in inconsistent signal intensities of the ultrasonic signals received by the probe at each moment. However, the signal intensities of the ultrasonic signals received by the probe at each moment without passing through the crack have strong consistency. Therefore, the greater the difference in the signal intensities corresponding to every two signal quantity ratios, and the greater the difference in the signal intensities of the ultrasonic signals received by the probe at each moment, the greater the possibility that a crack appears at the probe position.

[0042] Step S330: Obtain the crack possibility of the probe at each moment according to the intensity difference and the initial possibility.

[0043] It should be noted that the greater the initial possibility and the intensity difference, the greater the possibility that a crack appears at the probe position. Therefore, both the intensity difference and the initial possibility are positively correlated with the crack possibility. In the embodiments of the present invention, the product of the intensity difference and the initial possibility of the probe at each moment is normalized to obtain the crack possibility of the probe at each moment. The Norm function is used for normalization processing in the embodiments of the present invention.

[0044] Preferably, in some possible implementation manners of the embodiments of the present invention, the method for obtaining the corrected crack probability includes: performing normalization processing on the sum of the differences in the crack probability between each probe and its adjacent probe at each moment, and weighting the crack probability of each probe at each moment by using the processing result to obtain the corrected crack probability of each probe at each moment.

[0045] It should be noted that when there are fissures, the crack characteristics of the ultrasonic signals received by each probe are greater than those of the adjacent probes. Therefore, if the sum of the differences in the crack probability between each probe and its adjacent probe at each moment is larger, the probability of a crack at the probe position is greater, and the corrected crack probability of each probe is greater. In the embodiments of the present invention, the Norm function is used for normalization processing.

[0046] Preferably, in some possible implementation manners of the embodiments of the present invention, for the method for obtaining the crack probability, please refer to Figure 3 , which shows a flowchart of a method for obtaining the crack probability provided by an embodiment of the present invention. The method includes: Step S410: Calculate the cosine similarity of the feature vectors of each probe at each moment in each adjacent two moments within the historical analysis period, and perform a negative correlation mapping on the sum of all cosine similarities to obtain the signal disorder degree of each probe at each moment.

[0047] It should be noted that if there are fissures, there are differences in the crack characteristics of the ultrasonic signals at the same position at different moments; the difference degree of the crack characteristics is measured by the cosine similarity of the feature vectors of two moments. If the cosine similarity of the feature vectors of two adjacent moments within the historical analysis period is smaller, it indicates that the difference in the crack characteristics between adjacent moments is greater, the ultrasonic signal of each probe at each moment is more disordered, the signal disorder degree is greater, and the probability of a crack occurring at each probe is greater. In the embodiments of the present invention, the data to be processed is used as the exponent of an exponential function with the natural constant as the base to implement the negative correlation mapping of the data to be processed.

[0048] Step S420: Obtain the neighborhood signal similarity of each probe at each moment according to the difference in the corrected crack probability of each probe and its adjacent probe at all moments within the historical analysis period at each moment.

[0049] Preferably, in some possible implementation manners of the embodiments of the present invention, the method for obtaining the neighborhood signal similarity includes: arranging the corrected crack probability of each probe at all moments within the historical analysis period at each moment in chronological order to obtain the crack sequence of each probe at each moment; calculating the sum of the cosine similarities of the crack sequences of each probe and its adjacent probe at each moment as the neighborhood signal similarity of each probe at each moment.

[0050] It should be noted that the smaller the cosine similarity of the crack sequences of each probe and its adjacent probe at each moment, the smaller the similarity of the crack characteristics of the ultrasonic signals received by each probe and its adjacent probe during the historical analysis period at each moment. The smaller the neighborhood signal similarity, the greater the probability of cracks at the position of the probe.

[0051] Step S430: Obtain the crack probability of each probe at each moment according to the mean value of the corrected crack possibility of the crack sequence of each probe at each moment, the signal disorder degree, and the neighborhood signal similarity.

[0052] It should be noted that the greater the mean value of the corrected crack possibility of the crack sequence of the probe at each moment, the more it indicates that the crack characteristics are presented in the continuous time at the position of the probe, and the greater the probability of cracks at the position of the probe. At the same time, if the signal disorder degree is greater and the neighborhood signal similarity is smaller, the greater the probability of cracks in the probe. Therefore, both the mean value of the corrected crack possibility of the crack sequence of each probe at each moment and the signal disorder degree are positively correlated with the crack probability, and the neighborhood signal similarity is negatively correlated with the crack probability. In the embodiment of the present invention, a negative correlation mapping is performed on the signal disorder degree of each probe at each moment, and the product of the mapping result, the neighborhood signal similarity, and the mean value of the corrected crack possibility of the crack sequence of each probe at each moment is normalized to obtain the crack probability of each probe at each moment. In the embodiment of the present invention, the data to be processed is used as the exponent of the exponential function with the natural constant as the base to realize the negative correlation mapping of the data to be processed; the Norm function is used for normalization processing.

[0053] Preferably, in some possible implementation manners of the embodiment of the present invention, the crack detection method includes: determining whether the crack probabilities of all probes of each fault at all moments during the acquisition period meet a preset condition. If so, there are no cracks in each fault; otherwise, there are cracks in each fault. The preset condition is that the crack probabilities of all probes of each fault at all moments during the acquisition period are all less than a preset crack threshold, and the range of all crack probabilities is less than a preset fluctuation threshold.

[0054] In an implementation manner of the embodiment of the present invention, the preset crack threshold is 0.87, and the preset fluctuation threshold is set to 0.2.

[0055] So far, the present invention is completed.

[0056] Embodiment 2:

[0057] The present invention also proposes a schematic diagram of a computer device for a stone cultural relic crack detection device based on a concrete ultrasonic tomography scanner. Please refer to Figure 4, the computer device includes a memory 501, a processor 502, and a computer program 503 stored in the memory 501 and running on the processor 502. When the processor 502 executes the computer program 503, the computer device can execute any one of the above-described stone cultural relic crack detection methods based on a concrete ultrasonic tomography scanner.

[0058] In addition, an embodiment of the present application also protects a device, which may include a memory and a processor. Among them, an executable program code is stored in the memory, and the processor is used to call and execute the executable program code to execute a stone cultural relic crack detection method provided by an embodiment of the present application.

[0059] In this embodiment, the device can be divided into functional modules according to the above method examples. For example, it can correspond to each functional module, or two or more functions can be integrated into one processing module. The above integrated modules can be implemented in the form of hardware. It should be noted that the division of modules in this embodiment is illustrative, only a logical function division, and there may be other division methods in actual implementation.

[0060] In the case of dividing each module according to each function, the device may further include a communication module, a signal analysis module, a complexity analysis module, a positioning module, etc. It should be noted that all relevant contents of each step involved in the above method embodiment can be cited in the function description of the corresponding functional module, and will not be repeated here.

[0061] It should be understood that the device provided in this embodiment is used to execute the above-mentioned stone cultural relic crack detection method based on a concrete ultrasonic tomography scanner, so the same effect as the above implementation method can be achieved.

[0062] In the case of adopting an integrated unit, the device may include a processing module and a storage module. Among them, when the device is applied to a device, the processing module can be used to control and manage the actions of the device. The storage module can be used to support the device to execute mutual program codes, etc.

[0063] Among them, the processing module can be a processor or a controller, which can implement or execute various exemplary logical blocks, modules, and circuits included in the disclosure of the present application. The processor can also be a combination that realizes computing functions, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc. The storage module can be a memory.

[0064] Embodiment 3:

[0065] This embodiment also provides a computer-readable storage medium, in which computer program code is stored. When the computer program code runs on a computer, the computer is caused to execute the above-related method steps to implement a method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner provided in the above embodiment.

[0066] Embodiment 4:

[0067] This embodiment also provides a computer program product. When the computer program product runs on a computer, the computer is caused to execute the above-related steps to implement a method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner provided in the above embodiment.

[0068] Among them, the device, computer-readable storage medium, computer program product or chip provided in this embodiment are all used to execute the corresponding method provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding method provided above, and will not be elaborated here.

[0069] In the embodiments provided in this application, it should be understood that the disclosed device and method can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in electrical, mechanical or other forms.

[0070] It should be noted that the above sequence of the embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0071] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments.

Claims

1. A method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner, characterized in that, The method includes: When a concrete ultrasonic tomography scanner performs tomographic scanning on a stone cultural relic, acquiring the ultrasonic signals received by the probe for scanning each tomographic layer at each moment during the acquisition period, as well as the signal intensity, round-trip time, and acoustic path length of the ultrasonic signals; According to the number and signal intensity difference of the ultrasonic signals received by the probe for each tomographic layer at each moment, and the fluctuation degree of the acoustic path length of the ultrasonic signals, obtaining the crack characteristic value of the corresponding probe at each moment; According to the difference in the signal intensity and round-trip time of the ultrasonic signals received by each probe at each moment, and the crack characteristic value, obtaining the crack possibility of each probe at each moment; and adjusting the crack possibility of each probe at each moment by using the difference in the crack possibilities of each probe and its adjacent probes to obtain the corrected crack possibility; According to the similarity of the corrected crack possibilities of each probe and its adjacent probes within the historical analysis period at each moment, and the crack characteristic difference between adjacent moments of each probe within the historical analysis period at each moment, obtaining the crack probability of each probe at each moment; and performing crack detection on the stone cultural relic according to the crack probabilities of the probes on the same tomographic plane.

2. The crack detection method for stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 1, characterized in that The obtaining of the crack characteristic value of the corresponding probe at each moment includes: Obtaining the signal intensity of the ultrasonic wave emitted when the scanner performs tomographic scanning, denoted as the standard intensity; taking the difference between the standard intensity and the signal intensity of the ultrasonic signal as the ultrasonic loss; Selecting the ultrasonic signal corresponding to the minimum round-trip time from the ultrasonic signals received by the probe at each moment as the direct wave; According to the ultrasonic loss between the direct wave received by the probe at each moment and the remaining ultrasonic signals, and the number of ultrasonic signals, obtaining the abnormal loss degree of the probe at each moment; Denoting the acoustic path length corresponding to the direct wave as the ideal path length; performing normalization processing on the standard deviation of the absolute values of the differences between the acoustic path lengths of all the ultrasonic signals received by the probe at each moment and the ideal path length to obtain the distance fluctuation degree of the probe at each moment; Composing a feature vector of the probe at each moment from the abnormal loss degree and the distance fluctuation degree; taking the modulus length of the feature vector as the crack characteristic value of the probe at each moment.

3. A method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 2, characterized in that, The obtaining of the crack possibility of each probe at each moment includes: According to the difference in the signal intensity and round-trip time of the ultrasonic signals received by the probe at each moment, and the crack characteristic value, obtaining the initial possibility of the probe at each moment; Counting the proportion of the number of ultrasonic signals with each signal intensity in all the ultrasonic signals received by the probe at each moment, denoted as the signal volume ratio of each signal intensity, calculating the absolute value of the difference between the signal intensities corresponding to every two signal volume ratios, and averaging all the absolute values of the differences to obtain the intensity difference; According to the intensity difference and the initial possibility, obtaining the crack possibility of the probe at each moment.

4. The fissure detection method for stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 3, wherein, The obtaining of the initial possibility of the probe at each moment includes: Selecting the ultrasonic signal corresponding to the minimum signal intensity from the ultrasonic signals received by the probe at each moment as the strongest intensity signal; Calculate the absolute value of the difference in the round-trip time between the direct wave received by the probe at each moment and the strongest signal, and the absolute value of the difference in signal intensity, and use the product of the two absolute values of the differences as the signal difference degree; Obtain the initial possibility of the probe at each moment according to the signal difference degree and the crack characteristic value.

5. A method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 1, characterized in that, The method for obtaining the corrected crack possibility includes: Normalize the sum of the differences in the crack possibilities of each probe and its adjacent probes at each moment, and use the processing result to weight the crack possibility of each probe at each moment to obtain the corrected crack possibility of each probe at each moment.

6. The crack detection method for stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 2, characterized in that, The obtaining of the crack probability of each probe at each moment includes: Calculate the cosine similarity of the eigenvectors between every two adjacent moments within the historical analysis period of each probe at each moment, and perform a negative correlation mapping on the sum of all cosine similarities to obtain the signal disorder degree of each probe at each moment; Obtain the neighborhood signal similarity of each probe at each moment according to the difference in the corrected crack possibilities of each probe and its adjacent probes at all moments within the historical analysis period at each moment; Obtain the crack probability of each probe at each moment according to the mean value of the corrected crack possibilities of the crack sequence of each probe at each moment, the signal disorder degree, and the neighborhood signal similarity.

7. A method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 1, characterized in that The crack detection of the stone cultural relic according to the crack probabilities of the probes on the same fault plane includes: Judge whether the crack probabilities of all probes of each fault at all moments during the acquisition period meet the preset conditions. If so, there is no crack in each fault; if not, there is a crack in each fault; The preset conditions are: the crack probabilities of all probes of each fault at all moments during the acquisition period are all less than the preset crack threshold, and the range of all crack probabilities is less than the preset fluctuation threshold.

8. A method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 6, characterized in that, The obtaining of the neighborhood signal similarity of each probe at each moment includes: Arrange the corrected crack possibilities of each probe at all moments within the historical analysis period at each moment in chronological order to obtain the crack sequence of each probe at each moment; calculate the sum of the cosine similarities of the crack sequences of each probe and its adjacent probes at each moment as the neighborhood signal similarity of each probe at each moment.

9. A method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 6, characterized in that, The mean value of the corrected crack possibilities of the crack sequence of each probe at each moment, the signal disorder degree, and the neighborhood signal similarity are all positively correlated with the crack probability.

10. A method for detecting cracks in stone cultural relics based on a concrete ultrasonic tomography scanner according to claim 7, characterized in that, The preset crack threshold is 0.87.

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