Urban environment small loop frequency domain electromagnetic array detection device and method

Abstract

The invention relates to the field of geophysical electromagnetic methods, in particular to an urban environment small loop frequency domain electromagnetic array detection device and method, and the device comprises a transmitting system which is used for generating periodic sine wave current; the transmitting coil is connected with the transmitting system and used for transmitting a primary field to the underground, and the side length of the transmitting coil is smaller than 2 meters; the receiving coil array consists of a plurality of receiving coils and is used for receiving a secondary field signal induced by the underground structure; the receiving system is connected with the receiving coil array and is used for processing the received secondary field signal; and the hinge type mobile platform is used for carrying the receiving coil array and the receiving system and moving along the measuring line.The urban environment small loop frequency domain electromagnetic array detection device and method can rapidly detect in an urban area, and effectively solve the problem that a traditional frequency domain electromagnetic method instrument is low in detection efficiency.

Description

Technical Field

[0001] The present invention relates to the field of geophysical electromagnetic methods, and particularly to a small-loop frequency-domain electromagnetic array detection device and method for urban environments. Background Technique

[0002] The utilization of urban above-ground space is gradually approaching saturation, and the development and utilization of underground space have become a hot topic. Urban geological safety issues have become increasingly prominent. As a classic geophysical detection method, the electromagnetic method is widely used in fields such as environmental engineering and geological disaster monitoring. During detection, an excitation current is injected into an ungrounded loop through a transmitting system. According to the principle of electromagnetic induction, the underground medium generates a response signal, which is analyzed to obtain the distribution state of the underground electrical medium. This method has advantages such as non-destructiveness, high efficiency, and low cost. Therefore, detecting urban underground space through the electromagnetic method helps to increase the degree of underground exploration and improve development safety, which is of great significance.

[0003] According to the time-varying characteristics of the electromagnetic field and its mathematical description method, electromagnetic detection methods can be divided into two types: time domain and frequency domain. The time-domain electromagnetic method relies on the transient response signal generated at the moment when the transmitting current is turned off for detection. Its frequency spectrum range is relatively wide, and the energy distribution is relatively dispersed; while the frequency-domain electromagnetic method uses a periodic current with a fixed frequency as the excitation, so the spectral energy is concentrated at specific frequency points. In urban environments, due to the complex underground structure, high-conductivity targets such as metal pipelines will cause the rapid attenuation of electromagnetic wave energy. The time-domain electromagnetic method relies on the transient response signal for detection. In such an environment, the attenuation of its effective signal is more significant, affecting the detection efficiency.

[0004] Currently, the traditional fixed single-coil transmitting and receiving mode used in frequency-domain electromagnetic detection has low working efficiency. Due to the limited signal coverage range, it is difficult to effectively identify the complex electrical structures underground in cities, and its anti-interference ability is weak and is easily affected by interference sources such as metal pipelines. Therefore, in view of the above current situation, there is an urgent need to develop a small-loop frequency-domain electromagnetic array detection device and method for urban environments to overcome the deficiencies in current practical applications. Summary of the Invention

[0005] The purpose of the present invention is to provide a small-loop frequency-domain electromagnetic array detection device and method for urban environments to solve the problems raised in the above background technique.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A small-loop frequency-domain electromagnetic array detection device for urban environments, comprising: A transmitting system for generating a periodic sine wave current; A transmitting coil connected to the transmitting system for transmitting a primary field underground, and the side length of the transmitting coil is less than 2 meters; A receiving coil array, composed of multiple receiving coils, is used to receive the secondary field signals induced by underground structures; A receiving system, connected to the receiving coil array, is used to process the received secondary field signals; And a hinge-type mobile platform, which is used to carry the receiving coil array and the receiving system and move along the survey line.

[0007] As a further solution of the present invention: the number of receiving coils in the receiving coil array is n, numbered 1, 2,..., n, where the first receiving coil is the receiving coil closest to the transmitting coil.

[0008] As a further solution of the present invention: the hinge-type mobile platform can flexibly adjust the arrangement mode of the receiving coil array according to actual detection requirements.

[0009] A detection method for the urban environment small loop frequency domain electromagnetic array detection device described above includes the following steps: Step S1: Arrange a transmitting coil and a receiving coil array in the target area and the reference area respectively, transmit a primary field to the ground through the transmitting system, and receive the secondary field signals through the receiving coil array; Step S2: Perform relevant stacking processing on the vertical magnetic field components collected by the receiving coil array, and calculate the normalized anomaly ratio Q of the background fields in the target area and the reference area; Step S3: Introduce the reptile search algorithm in the meta-heuristic algorithm, and take the maximization of the normalized anomaly ratio Q as the goal to obtain the optimal constraint parameters; Step S4: Substitute the obtained optimal constraint parameters into the calculation of the normalized anomaly ratio Q in Step S2 to obtain the optimal normalized anomaly ratio Q, repeat the operation until all measurement points are completed, and obtain the underground electrical structure of the target area.

[0010] As a further solution of the present invention: in Step S1, the reference area is an area that is geographically close to the target area, has a similar geological structure, and has few interference sources.

[0011] As a further solution of the present invention: in Step S1, the transmitting frequency of the transmitting coil is a fixed frequency, and the receiving frequency of the receiving coil array is the same as the transmitting frequency, but the amplitude and phase change according to the underground electrical structure.

[0012] As a further solution of the present invention: in Step S2, the specific steps of the relevant stacking processing include: Perform constraint stacking on the response H of the receiving coil array in the target area to obtain the stacked response G of the target area. The specific formula is as follows: ; Among them, for n receiving coils, x is the receiving coil number, x ∈ [1, n], is the distance from the x-th receiving coil to the 1st receiving coil, is the position compensation coefficient, is the amplitude compensation coefficient, i is the imaginary unit, whose square is equal to -1, H x represents the vertical magnetic field component collected by the x-th receiving coil, e represents the natural number approximately equal to 2.718, represents the attenuation coefficient of the electromagnetic wave during propagation; The background field receiving coil array response of the reference area is directly superimposed to obtain the superimposed response of the reference area , and the specific formula is as follows: ; Among them, represents the vertical magnetic field component of the background field collected by the x-th receiving coil; Calculate the initial normalized anomaly ratio Q of the background fields of the target area and the reference area. Among them, the calculation formula of the normalized anomaly ratio Q is: .

[0013] As a further solution of the present invention: In step S3, the reptile search algorithm is used to optimize the constraint parameters, with -Q as the objective function, and the evolution factor is dynamically adjusted during the search process. The value range of the evolution factor is between 2 and -2.

[0014] As a further solution of the present invention: The reptile search algorithm is continuously iteratively optimized to minimize -Q, so as to obtain the maximum anomaly response.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention can quickly detect in urban areas, effectively solving the problem of low detection efficiency of traditional frequency domain electromagnetic method instruments; 2. Compared with single-coil reception, the present invention effectively highlights the underground anomaly response, improves the detection resolution, and has a faster inversion interpretation speed; 3. The mobile platform adopted by the present invention is hinged, and the number and arrangement mode of the receiving coil array can be flexibly adjusted according to the detection target and requirements, with strong flexibility and adaptability. Description of the Drawings

[0016] Figure 1 is a schematic diagram of the urban environment small loop frequency domain electromagnetic array detection device in the embodiment of the present invention; Among them, 1 - transmitting system, 2 - transmitting coil, 3 - receiving coil array, 4 - receiving system, 5 - hinged mobile platform.

[0017] Figure 2 It is a schematic diagram of the transmitted waveform and three typical received waveforms in a typical receiving coil array in the embodiment of the present invention.

[0018] Figure 3 It is a flowchart of the detection method of the small loop frequency domain electromagnetic array detection device in the urban environment in the embodiment of the present invention.

[0019] Figure 4 It is a flowchart of obtaining the optimal constraint parameters based on the reptile search algorithm in the embodiment of the present invention.

[0020] Figure 5 It is a schematic diagram of the numerical simulation model in the embodiment of the present invention.

[0021] Figure 6 It is a comparison diagram of the detection effects of a single receiving coil and the receiving coils of the array in the embodiment of the present invention; Among them, (a) is the magnitude of the background field and the total field of a single receiving coil, and (b) is the magnitude of the background field and the total field of the receiving coils of the array. Specific implementation mode

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] The following describes the specific implementation of the present invention in detail in conjunction with specific embodiments.

[0024] Please refer to Figures 1 - 6 , a small loop frequency domain electromagnetic array detection device provided by an embodiment of the present invention includes: A transmitting system 1 for generating a periodic sinusoidal current; A transmitting coil 2 connected to the transmitting system 1 for transmitting a primary field to the ground, and the side length of the transmitting coil 2 is less than 2 meters; A receiving coil array 3 composed of multiple receiving coils for receiving secondary field signals induced by underground structures; A receiving system 4 connected to the receiving coil array 3 for processing the received secondary field signals; And a hinged mobile platform 5 for carrying the receiving coil array 3 and the receiving system 4 and moving along the survey line.

[0025] In one embodiment of the present invention, the number of receiving coils in the receiving coil array 3 is n, labeled 1, 2, ..., n, where the first receiving coil is the receiving coil closest to the transmitting coil 2.

[0026] The hinge-type mobile platform 5 can flexibly adjust the arrangement mode of the receiving coil array 3 according to actual detection requirements.

[0027] In one embodiment of the present invention, a detection method for the urban environment small-loop frequency-domain electromagnetic array detection device described above includes the following steps: Step S1: Arrange the transmitting coil 2 and the receiving coil array 3 in the target area and the reference area respectively. Transmit the primary field into the ground through the transmitting system 1, and receive the secondary field signal through the receiving coil array 3; Among them, the three-dimensional frequency-domain finite-difference method is used to calculate the secondary response of the underground medium to the primary field, providing a theoretical reference for the received signal; Step S2: Perform correlation stacking processing on the vertical magnetic field components collected by the receiving coil array 3, and calculate the normalized anomaly ratio Q of the background fields in the target area and the reference area; Step S3: Introduce the reptile search algorithm in the meta-heuristic algorithm, and take the maximization of the normalized anomaly ratio Q as the goal to obtain the optimal constraint parameters; Step S4: Substitute the obtained optimal constraint parameters into the calculation of the normalized anomaly ratio Q in Step S2 to obtain the optimal normalized anomaly ratio Q. Repeat the operation until all measurement points are completed to obtain the underground electrical structure of the target area.

[0028] In one embodiment of the present invention, in Step S1, the reference area is an area that is geographically close to the target area, has a similar geological structure, and has few interference sources.

[0029] In Step S1, the transmitting frequency of the transmitting coil 2 is a fixed frequency, and the receiving frequency of the receiving coil array 3 is the same as the transmitting frequency, but the amplitude and phase change according to the underground electrical structure. Among them, each receiving coil in the receiving coil array 3 will receive the underground information at its location, and the amplitude and phase of the received signal of different receiving coils relative to the transmitted signal reflect the underground electrical structure (resistivity) at their locations.

[0030] In one embodiment of the present invention, in Step S2, the specific steps of the correlation stacking processing include: Perform constrained stacking on the response H of the receiving coil array in the target area to obtain the stacked response G of the target area. The specific formula is as follows: ; Among them, for n receiving coils, x is the receiving coil number, and x ∈ [1, n]. is the distance from the x-th receiving coil to the 1st receiving coil. is the position compensation coefficient. is the amplitude compensation coefficient, i is the imaginary unit, and its square is equal to -1. H x represents the vertical magnetic field component collected by the x-th receiving coil, and e represents the natural number approximately equal to 2.718. represents the attenuation coefficient of the electromagnetic wave during propagation. Directly superimpose the background field receiving coil array responses of the reference area to obtain the superimposed response of the reference area , and the specific formula is as follows: ; Among them, represents the vertical magnetic field component of the background field collected by the x-th receiving coil; Calculate the initial normalized anomaly ratio Q of the background fields of the target area and the reference area. Among them, the calculation formula of the normalized anomaly ratio Q is: .

[0031] In an embodiment of the present invention, in step S3, a reptile search algorithm is used to optimize the constraint parameters, with -Q as the objective function, and the evolution factor is dynamically adjusted during the search process. The value range of the evolution factor is between 2 and -2.

[0032] The reptile search algorithm continuously iterates and optimizes to minimize -Q, thereby obtaining the maximum anomaly response.

[0033] Embodiment 1: As Figure 1 shown, the small loop frequency domain electromagnetic array detection device in the urban environment of the present invention includes a transmitting system 1, a transmitting coil 2, a receiving coil array 3, a receiving system 4, and a hinged mobile platform 5.

[0034] As Figure 2 shown, it is a typical transmitting current waveform and receiving voltage waveform. The transmitting current is a periodic sine wave. Among them, the receiving voltage waveform is shown with 3 coils as an example, having the same frequency as the transmitting current, but different amplitude and phase changes, reflecting the electrical structure characteristics of different underground positions.

[0035] As Figure 3 shown, the detection method of the small loop frequency domain electromagnetic array detection device in the urban environment of the present invention includes: Step A: Construct a small loop frequency domain electromagnetic array detection device, and conduct detections in the target area and the reference area respectively. Step B: Using the reference area as the background field, calculate the normalized anomaly ratio Q at each measurement point; Step C: At each measurement point, aiming at the maximum normalized anomaly ratio Q, obtain the optimal constraint parameters based on the meta-heuristic algorithm; Step D: Repeat the above work until all measurement points are completed, and the underground geological electrical structure of the survey line can be obtained to end.

[0036] Embodiment 2: Step A specifically includes: defining the area to be detected as the target area, defining the area close to the geographical location of the survey area, with similar geological structures and few interference sources as the reference area, the data obtained from the reference area as the background field, arranging the transmitting coil 2 and the transmitting system 1 on the ground, arranging the receiving coil array 3 and the receiving system 4 on the hinge-type mobile platform 5, and the hinge-type mobile platform 5 moves along the survey line; The transmitting system 1 generates a periodic sine wave current through the transmitting coil 2 to emit a primary field to the underground; the receiving system 4 receives the secondary field signal induced by the underground structure through the receiving coil array 3 during the movement of the hinge-type mobile platform 5; define the receiving coil closest to the transmitting coil during detection as the first receiving coil, and the total number of receiving coils is n, and their labels are 1, 2,..., n; Detection depth Can be based on the skin depth formula Get, where Is the transmission frequency, Is the magnetic permeability of the underground medium, Is the electrical conductivity of the underground medium, and the attenuation coefficient of the electromagnetic wave during propagation ; Step B specifically includes: defining the vertical magnetic field component collected by the receiving coil array 3 as , using the amplitude and position of the receiving coil as constraints, perform correlation stacking processing on the data Received by the array, and obtain the expression of the normalized anomaly ratio Q of the background field between the target area and the reference area; Perform constraint stacking on the response H of the receiving coil array 3 in the target area to obtain the stacked response G of the target area. The specific formula is as follows: ; Among them, for n receiving coils, x is the receiving coil number, x ∈ [1, n], Is the distance from the xth receiving coil to the first receiving coil, Is the position compensation coefficient, Is the amplitude compensation coefficient, i is the imaginary unit, and its square is equal to -1, H x Represents the vertical magnetic field component collected by the xth receiving coil, e represents the natural number approximately equal to 2.718, Represents the attenuation coefficient of the electromagnetic wave during propagation; The background field receiving coil array 3 in the reference area responds to perform direct superposition to obtain the superposition response of the reference area , and the specific formula is as follows: ; wherein, represents the vertical magnetic field component of the background field collected by the x-th receiving coil; The ratio of the superimposed signal to the background field reference signal is Q. When Q is the largest, it is the most sensitive to the anomaly in the target detection area. At this time, it is the best interpretation result, and the specific formula is as follows: .

[0037] Step C specifically includes: introducing the reptilian search algorithm (RSA) in the meta-heuristic algorithm to obtain the constraint parameters and values. RSA is a global search by simulating the hunting behavior of crocodiles; since the objective function of the optimization algorithm usually can only obtain the minimum value, therefore, RSA uses -Q minimum as the objective function to obtain the best constraint parameters and values.

[0038] Step D specifically includes: substituting the best constraint parameters and into the calculation formula of the normalized anomaly ratio Q in step B to obtain the best normalized anomaly ratio Q, and finally obtain the normalized anomaly data of a certain point in the survey area and the background field area. Repeat this operation until all measuring points on the survey line are completed to obtain the underground structure of the target area.

[0039] Example 3: As Figure 4 shown, how to obtain the best constraint parameters and values through the reptilian search algorithm. The method includes: First of all, the targets to be optimized are and , so the optimization dimension s of the algorithm is 2. Subsequently, set the initial parameter population size N, the upper limit and the lower limit of the search range and the maximum number of iterations T; Perform population initialization according to the initial parameters: The position of the i-th individual in the j-th dimensional space is x (i,j) , is a random number, and each individual in each iteration is regarded as a candidate solution; ; When the maximum number of iterations is not reached, calculate the fitness function with the initial parameters and the current optimal solution. In the present invention, the fitness function is the same as the objective function, denoted as -Q. Subsequently, update the parameter evolution factors , R, P, and : ; ; ; ; Among them, the evolution factor randomly takes a decreasing value between 2 and -2 throughout the number of iterations; is used to reduce the search range; is the percentage difference between the optimal solution and the current solution, is the hunting operator of the j-th dimension in the i-th solution; t is the current number of iterations, is a random number; is the position of the j-th dimension of the current best solution, is a random number, represents the position of the j-th dimension of the 2 r-th candidate solution, is a minimum value used to ensure that the denominator is not zero. In the present invention, it is set to 0.001 according to experience; is a sensitive parameter that controls the difference between candidate solutions during the iteration process. In the present invention, it is set to 0.1 according to experience, is the average position of the i-th individual solution, and are the maximum and minimum values of the j-th dimension; T is the maximum number of iterations; ; Among them, s is the optimization dimension, and x (i,j) is the position of the i-th individual in the j-th dimensional space; After the parameter update is completed, enter the search stage, which can be divided into two stages: the surrounding stage and the hunting stage; The surrounding stage can be divided into two strategies: walking off the ground and walking on the ground. The mathematical model of this stage is: ; Among them, is the position of the i-th individual in the j-th dimensional space at the (t + 1)-th iteration, is a random number, represents the position of the j-th dimension of the 1 r-th candidate solution; The hunting stage can be divided into two strategies: hunting coordination and hunting cooperation. In this stage, an approximate optimal solution may be found after several iterations, and the search will be intensified near the optimal solution. The mathematical model in this stage is as follows: ; Among them, is a sensitive parameter used to control the search accuracy, which is set to 0.1 according to experience in the present invention, is a random number; Finally, the optimal solution in each iteration process is saved. When the number of iterations reaches the maximum number of iterations T, the search is completed and the current best constraint parameters and are returned.

[0040] Example 4: As Figure 5 shown, electromagnetic field calculations are carried out using the MATLAB2022b programming environment, and a numerical simulation model of a certain measurement point of the present invention is developed. The experiment uses the three-dimensional frequency-domain finite-difference method to obtain data. The size of the entire formation calculation space is 200m×100m×100m, the size of the air layer is the same as that of the formation, the resistivity of the air layer is 10 8 Ω·m, and the resistivity of the underground background layer is 100Ω·m; the size of the anomaly is 10m×10m×20m, the depth from the center is 20m, the lateral distance is 27m, and it is symmetrically distributed. The resistivity of the anomaly is 300Ω·m; the excitation source is at the center and is symmetrically distributed. For the convenience of numerical simulation, its shape is set as a square, the emission frequency is 2kHz, the emission current is 30A, and the side length is 2m; the side length of the receiving coil array 3 is 1m, the edge interval is 1m, and the distance from the first receiving coil to the center of the transmitting coil 2 is 25m; the overall grid uses variable-step meshing. The grid is meshed into 0.1m where there are coils and anomalies, and the grid is sparse in other places.

[0041] As Figure 6 shown, for the experimental results of this model, the population size is set to 500, the number of iterations is set to 100, the search upper limit is set to 200, and the lower limit is set to 0, and the iteration starts; it can be seen that when detecting with a single coil, the difference between the background field and the total field is not significant, as shown in (a) of Figure 6 ; however, when detecting using the device and method of the present invention, the difference between the background field and the total field is obvious, as shown in (b) of Figure 6 , which proves the superiority of the detection method proposed by the present invention.

[0042] In summary, to further improve the detection efficiency and flexibility of the detection method, the detection device can be carried on a mobile platform. The emission source adopts a small loop form (with a side length less than 2 meters due to the complex urban space), and the receiving coil array 3 is used for reception to improve the signal coverage and system sensitivity. In addition, based on the signal correlation between the receiving coil arrays 3, the detection resolution and applicability in complex urban environments can be further improved.

[0043] It should be noted that in the present invention, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A small loop frequency domain electromagnetic array detection device for urban environment, characterized in that: include: A transmitting system for generating a periodic sinusoidal current; A transmitting coil, connected to the transmitting system, for transmitting a primary field underground, wherein the side length of the transmitting coil is less than 2 meters; A receiving coil array, composed of a plurality of receiving coils, for receiving secondary field signals induced by underground structures; A receiving system, connected to the receiving coil array, for processing the received secondary field signal; and a hinged mobile platform, which is used to carry the receiving coil array and the receiving system and move along the survey line.

2. The urban environment small loop frequency domain electromagnetic array detection device according to claim 1 is characterized in that: The number of receiving coils in the receiving coil array is n, which are numbered 1, 2, ..., n, wherein the first receiving coil is the receiving coil closest to the transmitting coil.

3. The urban environment small loop frequency domain electromagnetic array detection device according to claim 2 is characterized in that: The hinged mobile platform can flexibly adjust the arrangement of the receiving coil array according to actual detection requirements.

4. A detection method according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1, arranging a transmitting coil and a receiving coil array in the target area and the reference area respectively, transmitting a primary field underground through a transmitting system, and receiving a secondary field signal through a receiving coil array; Step S2, performing correlation superposition processing on the vertical magnetic field components collected by the receiving coil array, and calculating the normalized anomaly ratio Q of the background field of the target area and the reference area; Step S3, introducing the reptile search algorithm in the meta-heuristic algorithm, taking the maximization of the normalized anomaly ratio Q as the goal, and obtaining the optimal constraint parameters; Step S4, substituting the obtained optimal constraint parameters into the calculation of the normalized anomaly ratio Q in step S2 to obtain the optimal normalized anomaly ratio Q, repeating the operation until all measuring points are completed to obtain the underground electrical structure of the target area.

5. The urban environment small loop frequency domain electromagnetic array detection method according to claim 4 is characterized in that: In step S1, the reference area is an area that is geographically close to the target area, has a similar geological structure, and has few interference sources.

6. The urban environment small loop frequency domain electromagnetic array detection method according to claim 4 is characterized in that: In step S1, the transmitting frequency of the transmitting coil is a fixed frequency, and the receiving frequency of the receiving coil array is the same as the transmitting frequency, but the amplitude and phase vary according to the underground electrical structure.

7. The urban environment small loop frequency domain electromagnetic array detection method according to claim 4 is characterized in that: In step S2, the specific steps of the correlation superposition processing include: The receiving coil array response H of the target area is constrained and superimposed to obtain the superimposed response G of the target area. The specific formula is as follows: ； Among them, for n receiving coils, x is the receiving coil number, x∈[1,n], is the distance from the xth receiving coil to the first receiving coil, is the position compensation coefficient, is the amplitude compensation coefficient, i is an imaginary unit, its square is equal to -1, H x represents the vertical magnetic field component collected by the xth receiving coil, and e represents a natural number of approximately 2.

718. It represents the attenuation coefficient of electromagnetic waves during propagation; The background field of the reference area receives the coil array response Perform direct superposition to obtain the superposition response of the reference area , the specific formula is as follows: ； in, Represents the vertical magnetic field component of the background field collected by the xth receiving coil; Calculate the initial normalized anomaly ratio Q of the target area and the background field of the reference area, where the calculation formula of the normalized anomaly ratio Q is: 。 8. The urban environment small loop frequency domain electromagnetic array detection method according to claim 4 is characterized in that: In step S3, the constraint parameters are optimized using a reptile search algorithm, with -Q as the objective function. The evolution factor is dynamically adjusted during the search process, and the value range of the evolution factor is between 2 and -2.

9. The urban environment small loop frequency domain electromagnetic array detection method according to claim 8, characterized in that: The reptile search algorithm is optimized through continuous iteration to minimize -Q, thereby obtaining the maximum abnormal response.

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