Air-sea ice-seawater underwater target excitation electric field simulation method and system

Abstract

The invention discloses an air-sea ice-seawater underwater target excitation electric field simulation method and system. The method comprises the following steps: establishing an underwater metal target material corrosion polarization characteristic model; establishing a target equivalent source electric field model based on boundary conditions provided by material polarization characteristics; constructing a cylindrical coordinate system of which the depth direction is z and the radius direction is r; determining a potential Vi expression of any position in the ith layer generated by a point current source of the current; calculating the potentials of the layer boundary Zi and the upper layer boundary Zi-1; calculating the potential relationship when the point current source is placed in the layer; the air-sea ice-seawater three-layer resistivity model is designed, and an air layer, a sea ice layer and a seawater layer are sequentially arranged from top to bottom in the vertical direction. Compared with an existing underwater target electromagnetic field model, the model emphatically considers boundary conditions in a special low-temperature environment, and provides a research basis for researching the electric field of the underwater target in the special environment.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater target electromagnetic fields, and in particular to a method and system for simulating the electric field excitation of an underwater target in air-sea ice-sea water. Background Art

[0002] In the theoretical research and engineering applications of underwater electromagnetic field technology, the construction of medium models is crucial for accurately analyzing the electromagnetic field characteristics of underwater targets. Currently, the mainstream medium models mainly fall into two categories.

[0003] One type is the air-seawater two-layer model. This model considers only the air and seawater media. Its advantages are its relative simplicity and minimal computational effort, making it applicable to research requiring less precise accuracy or related to the seawater surface. For example, this simple two-layer model can provide a preliminary analytical framework for studying electromagnetic interference near the sea surface. However, because it ignores many real-world factors, such as the stratified nature of seawater and the effects of impurities and suspended matter on the electromagnetic field, it has significant limitations in describing complex real-world scenarios.

[0004] Another type is the three-layer air-seawater-seabed model. This model, based on the two-layer air-seawater model, further considers the influence of the seabed, typically placing the source point in the third seabed layer. The presence of the seabed can significantly affect the electromagnetic field of underwater targets, as factors such as the seabed's geological structure and material composition alter the propagation path and intensity distribution of the electromagnetic field. This model has certain applications in fields such as seabed resource exploration and submarine cable electromagnetic environment analysis. However, it also has shortcomings. For example, the assumptions about the seabed's characteristics during the simulation process are often oversimplified, failing to fully account for the complexity and diversity of the seabed. Furthermore, the potential for sea ice layers in low-temperature environments is also not considered.

[0005] In actual low-temperature environments, especially in polar regions or high-latitude waters, a layer of sea ice composed of frozen seawater often forms between the air layer and the seawater layer. The sea ice layer is a composite material layer composed of pure ice crystals, brine, bubbles, and other impurities, and its physical and electrical properties are very different from those of air and seawater. The presence of the sea ice layer has a unique impact on the electromagnetic field of underwater targets. For example, the dielectric constant and conductivity of the sea ice layer differ from those of seawater and air, which causes the electromagnetic field to refract, reflect, and attenuate when passing through the sea ice layer. However, the existing air-seawater two-layer model and the air-seawater-seabed three-layer model do not take the sea ice layer into account, resulting in a low degree of fit between these models and the actual low-temperature environment.

[0006] With the increasing demand for polar resource development, polar scientific expeditions, and military activities in low-temperature waters, it is increasingly urgent to accurately study the electromagnetic field characteristics of underwater targets in low-temperature environments. Currently, there is a lack of an effective method to accurately simulate the electric field excited by underwater targets in the air-sea ice-seawater medium, which limits the development of related fields. For example, in polar marine engineering construction, an accurate understanding of the electromagnetic field distribution of underwater targets is required to ensure the normal operation and safety of engineering equipment, but existing models cannot provide reliable simulation results. Therefore, designing a numerical simulation method for the electric field excited by an equivalent source based on the air-sea ice-seawater medium model has important engineering value and practical application needs. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology. In view of the problem that the existing air-seawater-seabed model has a low degree of compatibility with the actual low-temperature environment, a method for simulating the electric field of underwater targets excited in air-sea ice-seawater is proposed to carry out more accurate analysis.

[0008] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a method for simulating the electric field of underwater target excitation in air-sea ice-sea water, comprising:

[0009] S1. Establish a corrosion polarization characteristic model for underwater metal target materials;

[0010] S2. Establish the target equivalent source electric field model based on the boundary conditions provided by the material polarization characteristics;

[0011] S3. Establish an electric field model of an equivalent source in a low-temperature environment with air, sea ice, and seawater:

[0012] Construct a cylindrical coordinate system with depth direction z and radius direction r;

[0013] Determine the potential V at any location in the i-th layer generated by the point current source i expression;

[0014] Calculate layer boundary Z i and the upper boundary Z i-1 The potential of

[0015] Calculate the relationship between the potentials when a point current source is placed within the layer;

[0016] The design of the three-layer resistivity model of air-sea ice-sea water has been completed. From the vertical direction from top to bottom, it is the air layer, sea ice layer, and sea water layer.

[0017] Furthermore, in S1, a corrosion polarization characteristic model of underwater metal target materials is established, and the specific steps are as follows:

[0018] Processing metals of different materials into discs of the same area as electrode materials;

[0019] The three-electrode system was used for testing, with Ag / AgCl as the reference electrode, Pt sheet electrode as the counter electrode, and the sample to be tested as the working electrode.

[0020] The electrolytic cells were placed in different temperature environments and the electrochemical impedance spectroscopy was tested for a certain period of time.

[0021] After the electrochemical test, the samples were cleaned with pure water and anhydrous ethanol and dried, the surface morphology was observed under an optical microscope, and the electrochemical impedance spectrum and polarization curves of the metal materials at different temperatures were plotted.

[0022] Furthermore, the establishment of the underwater metal target material corrosion polarization characteristic model further includes the following steps:

[0023] Set the electrochemical impedance spectroscopy perturbation signal, frequency range, and sweep mode, and use the fitting circuit to analyze the data;

[0024] After a certain period of time, the open circuit potential of the metal test piece is stabilized and a dynamic potential scanning polarization curve test is performed.

[0025] Furthermore, the method for establishing the target equivalent source electric field model in S2 is:

[0026] The electrochemical impedance spectroscopy and polarization curves provide boundary conditions for the target equivalent source electric field model. In three-dimensional space, the Laplace equation satisfied by the equivalent source electric field distribution under different polarization conditions is as follows:

[0027]

[0028] Where, is the Laplace operator, and u(x,y,z) is a function of x, y, and z in three-dimensional space.

[0029] Furthermore, the boundary conditions provided by the material polarization characteristics in S2 are as follows:

[0030] The linear polarization boundary is expressed as follows:

[0031]

[0032] Where J is the polarization current density, E is the polarization potential, E0 is the equilibrium potential, and R p is the linear polarization resistance;

[0033] The nonlinear polarization boundaries are as follows:

[0034]

[0035] Where, j 0 is the corrosion current density, b a 、b c is the anode and cathode Tafel slope.

[0036] Furthermore, the potential V in S3 i The expression is as follows:

[0037]

[0038] In the above formula, V i (r,z) represents the potential value at a depth of z in the i-th layer of the medium, which is a distance r from the central axis of the cylindrical coordinate system; r represents the value in the depth direction, z represents the value in the radius direction, and λ represents the wave number in the wave number domain. represents the upward decay part of the potential, Indicates the downward attenuation part; zz i ≤0, U i and D i are coefficients determined by the boundary conditions, and J0 is the Bessel function of the first kind and order 0.

[0039] Furthermore, the calculation layer boundary Z is calculated in S3 i and the upper boundary Z i-1 The potential method is as follows:

[0040] Layer boundary z = z i and the upper boundary z = z i-1 The potential is:

[0041]

[0042]

[0043] Among them, V i (r,z i-1 ) is the layer i medium at the layer boundary z=z i-1 The potential at i-1 (r,z i-1 ) is the i-1th layer of medium at the layer boundary z=z i-1 The potential at i and D i Considered as layer boundary z=z i The coefficient just above, and Considered as layer boundary z=z i-1 The coefficients directly below, and thus:

[0044]

[0045] Where λ represents the wave number in the wave number domain, I is the excitation current, and u i =exp(-λh i ),u i represents the propagation coefficient of the i-th layer medium, h i is the thickness of the dielectric layer, J0 is the Bessel function of the first kind and order 0;

[0046] Resistivity at the layer boundary z = z i-1 The boundary changes that occur require the following boundary conditions to be met:

[0047] V i (r,z i-1 )=V i-1 (r,z i-1 )

[0048]

[0049] Then we can get:

[0050]

[0051] r i-1 , t i-1 The layer boundaries z = z i-1 The reflection coefficient and transmission coefficient at , and satisfy:

[0052]

[0053] Among them, ρ i represents the resistivity of the i-th layer of medium, ρ i-1 Represents the resistivity of the i-1th layer medium.

[0054] Furthermore, the relationship method for calculating the potential when the point current source is placed in the layer in S3 is as follows:

[0055] Set a virtual boundary, the upper layer is the first The layer below is the mth layer, and the depth of the point current source inside the layer is z=z c , since the reflection coefficient of this boundary is zero, we can get:

[0056]

[0057] Among them, u m =exp(-λh m ), ρ m represents the resistivity of the mth layer of medium, u m represents the propagation coefficient of the mth layer medium;

[0058] The integral of the above Bessel function is filtered using the fast Hankel filter method, and the integral of the Bessel function on the interval (0, +∞) is recorded as g(r):

[0059]

[0060] J v It is the first kind Bessel function of order v, real number v>-1, and the transformation formula is introduced:

[0061]

[0062] Where u, v∈(-∞, +∞), u and v are new variables in the fast Hankel transform; r0 is a selected constant, and the following function is defined:

[0063]

[0064] Combining the above conditions, g(r) can be written as:

[0065]

[0066] Where G(v) is the function F and H v Convolution of H v =J v (e u )e u , is the convolution kernel function, which is used to convert the original integral into the convolution form; g(r) represents the result after fast Hankel filtering; f(λ) represents a part of the integrand, which represents the source term or known function related to the problem;

[0067] Sampling F(u) using the sampling function P(x) = sin(πx) / πx and discretizing v yields:

[0068]

[0069] Where Δ<1 / |2f|, Δ is the sampling interval, f is the highest frequency of the sampling function; r0 is the constant used to scale the radial coordinates and wavenumbers in the fast Hankel transform; n is the index of the discrete sample point; m is another index in the discrete convolution; the fast Hankel transform filter coefficient H is v for:

[0070]

[0071] Where H v represents the fast Hankel transform filter coefficient; represents the processed fast Hankel transform filter coefficient; P represents the sampling function, and Δ represents the sampling interval.

[0072] As a second aspect of the present invention, there is also provided a system for simulating an underwater target excitation electric field in an air-sea ice-seawater environment, comprising:

[0073] Establishing a corrosion polarization characteristic model unit for underwater metal target materials, which is used to establish a corrosion polarization characteristic model for underwater metal target materials;

[0074] A target equivalent source electric field model unit is established based on the boundary conditions provided by the material polarization characteristics, and is used to establish the target equivalent source electric field model based on the boundary conditions provided by the material polarization characteristics;

[0075] Establish an electric field model unit of an equivalent source in a low-temperature ambient air-sea ice-seawater medium to complete the following steps:

[0076] Construct a cylindrical coordinate system with depth direction z and radius direction r;

[0077] Determine the potential V at any location in the i-th layer generated by the point current source i expression;

[0078] Calculate layer boundary Z i and the upper boundary Z i-1 The potential of

[0079] Calculate the relationship between the potentials when a point current source is placed within the layer;

[0080] The design of the three-layer resistivity model of air-sea ice-sea water has been completed. From the vertical direction from top to bottom, it is the air layer, sea ice layer, and sea water layer.

[0081] As a third aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, and the computer program is used by a processor to execute any step of the method for simulating the electric field of underwater target excitation in air-sea ice-sea water.

[0082] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0083] 1. The present invention's method for simulating the electric field excitation of underwater targets in air, sea ice, and seawater establishes an electric field model of an equivalent source in a low-temperature air, sea ice, and seawater medium. Firstly, it accurately fills the gap in existing offshore medium models that do not include sea ice layers, highly consistent with actual low-temperature environments, making simulation results closer to reality and greatly improving the matching degree between the model and actual scenarios. Secondly, it lays a solid foundation for the study of electromagnetic fields of underwater targets in polar environments, enabling more accurate simulation of the electric field excitation of underwater targets, assisting researchers in in-depth analysis of the electromagnetic field characteristics of underwater targets in complex media, and providing reliable technical support for related engineering applications. This method has groundbreaking significance and extremely high application value in the field of underwater target electromagnetic field technology.

[0084] 2. The method for simulating the electric field of underwater target excitation in air-sea ice-seawater of the present invention establishes a corrosion polarization characteristic model of underwater metal target materials, fits the electrochemical impedance spectra and polarization curves of different materials at different temperatures, and obtains the material polarization characteristics; based on the boundary conditions provided by this, a target equivalent source electric field model is established to determine the theoretical framework of the electric field distribution; then, an electric field model of the equivalent source in the air-sea ice-seawater medium in a low-temperature environment is established, taking into account the key factor missing from the existing model, the cylindrical coordinate system, multiple mathematical methods, and a specific resistivity model and observation system settings are used to realize the numerical simulation of the underwater target excitation electric field in the air-sea ice-seawater medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 This is a flow chart of a method for simulating an underwater target excitation electric field in air-sea ice-sea water according to an embodiment of the present invention;

[0086] Figure 2 is a schematic diagram of a low-temperature electrochemical test according to an embodiment of the present invention;

[0087] Figure 3 is an equivalent circuit diagram used for electrochemical impedance spectroscopy fitting in an embodiment of the present invention;

[0088] Figure 4 1 is a schematic diagram (cylindrical coordinate system) of a point current source in a cylindrical horizontal layered medium according to an embodiment of the present invention;

[0089] Figure 5 It is a graph of the upward and downward extension of U and D within a layer through the layer boundary in an embodiment of the present invention;

[0090] Figure 6 is a diagram of upward and downward connections through an imaginary horizontal plane including a point current source according to an embodiment of the present invention;

[0091] Figure 7 This is an overview of the air-sea ice-seawater three-layer geoelectric model and survey line positions in an embodiment of the present invention;

[0092] Figure 8 Schematic diagram of system units according to an embodiment of the present invention. DETAILED DESCRIPTION

[0093] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0094] Example 1.

[0095] Please refer to Figure 1 This embodiment 1 provides a method for simulating an underwater target excitation electric field in air-sea ice-sea water, including:

[0096] S1. Establish a corrosion polarization characteristic model for underwater metal target materials;

[0097] S2. Establish the target equivalent source electric field model based on the boundary conditions provided by the material polarization characteristics;

[0098] S3. Establish an electric field model of an equivalent source in a low-temperature environment with air, sea ice, and seawater:

[0099] Construct a cylindrical coordinate system with depth direction z and radius direction r;

[0100] Determine the potential V at any location in the i-th layer generated by the point current source i expression;

[0101] Calculate layer boundary Z i and the upper boundary Z i-1 The potential of

[0102] Calculate the relationship between the potentials when a point current source is placed within the layer;

[0103] The design of the three-layer resistivity model of air-sea ice-sea water has been completed. From the vertical direction from top to bottom, it is the air layer, sea ice layer, and sea water layer.

[0104] The following is a further explanation of the above steps:

[0105] (1) Establish a corrosion polarization characteristic model for underwater metal target materials;

[0106] Please refer to Figure 2 , Figure 2 The figure is a schematic diagram of the low-temperature electrochemical test described in the present invention. Disks of different metal materials are processed into discs of equal area to serve as electrode materials. Wires are soldered to the back and then encapsulated. The working surfaces are polished with sandpaper of varying grits, cleaned, and dried with alcohol before use. A three-electrode system is used for testing, with an Ag / AgCl reference electrode, a Pt sheet electrode as the counter electrode, and the sample to be tested as the working electrode. Electrolytic cells are placed in different temperature environments, and electrochemical impedance spectroscopy is measured for a specific period of time.

[0107] Please refer to Figure 3 , set the electrochemical impedance spectroscopy disturbance signal, frequency range, sweep mode, and use Figure 3The data was analyzed using the fitting circuit shown in the equivalent circuit diagram. After a certain period of time, the open-circuit potential of the metal specimen stabilized, and a potentiodynamic scanning polarization curve test was performed. After the electrochemical test, the specimen was cleaned with pure water and anhydrous ethanol, then dried. The surface morphology was observed under an optical microscope, and the electrochemical impedance spectrum and polarization curves of the metal material at different temperatures were plotted.

[0108] (2) Establishing the target equivalent source electric field model based on the boundary conditions provided by the material polarization characteristics;

[0109] The electrochemical impedance spectroscopy and polarization curves in step S1 provide boundary conditions for the target equivalent source electric field model. In three-dimensional space, the Laplace equation satisfied by the equivalent source electric field distribution under different polarization conditions is as follows:

[0110]

[0111] Where, is the Laplace operator, and u(x,y,z) is a function of x, y, and z in three-dimensional space.

[0112] The constant potential boundary is Where U is the boundary surface potential distribution, is a constant;

[0113] The linear polarization boundary is expressed as follows:

[0114]

[0115] Where J is the polarization current density, E is the polarization potential, E0 is the equilibrium potential, and R p is the linear polarization resistance;

[0116] The nonlinear polarization boundaries are as follows:

[0117]

[0118] Where, j 0 is the corrosion current density, b a 、b c is the anode and cathode Tafel slope.

[0119] (3) Establish an electric field model of an equivalent source in a low-temperature environment with air, sea ice, and seawater

[0120] Please refer to Figure 4 , Figure 4Schematic diagram of the DC potential response model for an arbitrary electrode arrangement in a horizontal multilayer structure, using a cylindrical coordinate system with depth z and radius r. The potential generated in the formation is the first-order field generated by the current source itself and the second-order field generated by stored charge at the formation boundary where the resistivity changes. The closer to the current source or stored charge, the greater the electric field, and vice versa. The potential V at any position (r, z) in the i-th layer generated by a point current source with current I is i as follows:

[0121]

[0122] In the above formula, V i (r,z) represents the potential value at a depth of z in the i-th layer of the medium, which is a distance r from the central axis of the cylindrical coordinate system; r represents the value in the depth direction, z represents the value in the radius direction, and λ represents the wave number in the wave number domain. represents the upward decay part of the potential, Indicates the downward attenuation part; zz i ≤0, U i and D i are coefficients determined by the boundary conditions, and J0 is the Bessel function of the first kind and order 0.

[0123] Please refer to Figure 5 , Figure 5 U and D are extended upward and downward through the layer boundary within the layer, and the layer boundary z = z i and the upper boundary z = z i-1 The potential is:

[0124]

[0125] Among them, V i (r,z i-1 ) is the layer i medium at the layer boundary z=z i-1 The potential at i-1 (r,z i-1 ) is the i-1th layer of medium at the layer boundary z=z i-1 The potential at i and D i Considered as layer boundary z=z i The coefficient just above, and Considered as layer boundary z=z i-1 The coefficients directly below, and thus:

[0126]

[0127] Where λ represents the wave number in the wave number domain, I is the excitation current, and u i =exp(-λh i ),ui represents the propagation coefficient of the i-th layer medium, h i is the thickness of the dielectric layer, J0 is the Bessel function of the first kind and order 0;

[0128] Resistivity at the layer boundary z = z i-1 The boundary changes that occur require the following boundary conditions to be met:

[0129] V i (r,z i-1 )=V i-1 (r,z i-1 )

[0130]

[0131] Then we can get:

[0132]

[0133] r i-1 , t i-1 The layer boundaries z = z i-1 The reflection coefficient and transmission coefficient at , and satisfy:

[0134]

[0135] Among them, ρ i represents the resistivity of the i-th layer of medium, ρ i-1 Represents the resistivity of the i-1th layer medium.

[0136] Please refer to Figure 6 , Figure 6 For the upward and downward connections through an imaginary horizontal plane containing a point current source, calculate the relationship of the potential when the point current source is placed within the layer:

[0137] Set a virtual boundary, the upper layer is the first The layer below is the mth layer, and the depth of the point current source inside the layer is z=z c . Since the reflection coefficient of this boundary is zero, we can get:

[0138]

[0139] Among them, u m =exp(-λh m ), ρ m represents the resistivity of the mth layer of medium, u m represents the propagation coefficient of the mth layer medium;

[0140] The integral of the above Bessel function is filtered using the fast Hankel filter method, and the integral of the Bessel function on the interval (0, +∞) is recorded as g(r):

[0141]

[0142] J v It is the first kind Bessel function of order v, real number v>-1, and the transformation formula is introduced:

[0143]

[0144] Where u, v∈(-∞, +∞), u and v are new variables in the fast Hankel transform; r0 is a selected constant, and the following function is defined:

[0145]

[0146] Combining the above conditions, g(r) can be written as:

[0147]

[0148] Where G is the function F and H v Convolution of H v =J v (e u )e u , is the convolution kernel function, which is used to convert the original integral into the convolution form; g(r) represents the result after fast Hankel filtering; f(λ) represents a part of the integrand, which represents the source term or known function related to the problem;

[0149] Sampling F(u) using the sampling function P(x) = sin(πx) / πx and discretizing v yields:

[0150]

[0151] Where Δ<1 / |2f|, Δ is the sampling interval, f is the highest frequency of the sampling function; r0 is the constant used to scale the radial coordinates and wavenumbers in the fast Hankel transform; n is the index of the discrete sample point; m is another index in the discrete convolution; the fast Hankel transform filter coefficient H is v for:

[0152]

[0153] Where H v represents the fast Hankel transform filter coefficient; represents the processed fast Hankel transform filter coefficient; P represents the sampling function, and Δ represents the sampling interval.

[0154] Please refer to Figure 7 , Figure 7The simple typical air-sea ice-sea water three-layer resistivity model is designed. From the vertical direction, the air layer is arranged from top to bottom, and the resistivity is set to 10 12 Ω·m; the sea ice layer floats on the seawater interface, has a thickness of 2m, and its resistivity is set to 50Ω·m; the seawater resistivity is set to 0.3Ω·m, and is assumed to extend infinitely downward. A rectangular coordinate system is established with the sea ice and seawater interface as the xy plane and the z-axis pointing vertically downward as the positive direction. The center point of the dipole source is located at (0, 0, 200), and the length of the dipole source along the x-direction is set to 1m. The observation system is set up with a single survey line with a 200m offset in the y-direction, that is, the center point of the survey line is located at (0, 200, 0), and it extends 2000m to the left and right along the x-axis. The measurement point spacing is designed to be 20m, resulting in a total of 201 measurement points.

[0155] Example 2

[0156] Please refer to Figure 8 This embodiment 2 provides an underwater target excitation electric field simulation system in air-sea ice-sea water, including:

[0157] Establishing a corrosion polarization characteristic model unit for underwater metal target materials, which is used to establish a corrosion polarization characteristic model for underwater metal target materials;

[0158] A target equivalent source electric field model unit is established based on the boundary conditions provided by the material polarization characteristics, and is used to establish the target equivalent source electric field model based on the boundary conditions provided by the material polarization characteristics;

[0159] Establish an electric field model unit of an equivalent source in a low-temperature ambient air-sea ice-seawater medium to complete the following steps:

[0160] Construct a cylindrical coordinate system with depth direction z and radius direction r;

[0161] Determine the potential V at any location in the i-th layer generated by the point current source i expression;

[0162] Calculate layer boundary Z i and the upper boundary Z i-1 The potential of

[0163] Calculate the relationship between the potentials when a point current source is placed within the layer;

[0164] The design of the three-layer resistivity model of air-sea ice-sea water has been completed. From the vertical direction from top to bottom, it is the air layer, sea ice layer, and sea water layer.

[0165] Example 3

[0166] This embodiment 3 also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it can implement any step of the underwater target excitation electric field simulation method in air-sea ice-sea water.

[0167] The computer-readable storage medium may include: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc., which can store program codes.

[0168] For an introduction to the computer-readable storage medium provided in this application, please refer to the above method embodiment, and this application will not go into details here.

[0169] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for simulating the electric field of underwater target excitation in air-sea ice-sea water, characterized in that: include: S1. Establish a corrosion polarization characteristic model for underwater metal target materials; S2. Establish the target equivalent source electric field model based on the boundary conditions provided by the material polarization characteristics; S3. Establish an electric field model of an equivalent source in a low-temperature environment with air, sea ice, and seawater: Construct a cylindrical coordinate system with depth direction z and radius direction r; Determine the potential V at any location in the i-th layer generated by the point current source of current I i expression; Calculate layer boundary Z i and the upper boundary Z i-1 The potential of Calculate the relationship between the potentials when a point current source is placed within the layer; The design of the three-layer resistivity model of air-sea ice-sea water has been completed. From the vertical direction from top to bottom, it is the air layer, sea ice layer, and sea water layer.

2. The method for simulating the electric field of underwater target excitation in air-sea ice-sea water according to claim 1, characterized in that: In S1, a corrosion polarization characteristic model of underwater metal target materials is established, and the specific steps are as follows: Processing metals of different materials into discs of the same area as electrode materials; The three-electrode system was used for testing, with Ag / AgCl as the reference electrode, Pt sheet electrode as the counter electrode, and the sample to be tested as the working electrode. The electrolytic cells were placed in different temperature environments and the electrochemical impedance spectroscopy was tested for a certain period of time. After the electrochemical test, the samples were cleaned with pure water and anhydrous ethanol and dried, the surface morphology was observed under an optical microscope, and the electrochemical impedance spectrum and polarization curves of the metal materials at different temperatures were plotted.

3. The method for simulating the electric field of underwater target excitation in air-sea ice-sea water according to claim 2, characterized in that: The method of establishing the underwater metal target material corrosion polarization characteristic model further includes the following steps: Set the electrochemical impedance spectroscopy perturbation signal, frequency range, and sweep mode, and use the fitting circuit to analyze the data; After a certain period of time, the open circuit potential of the metal test piece is stabilized and a dynamic potential scanning polarization curve test is performed.

4. The method for simulating the electric field of underwater target excitation in air-sea ice-sea water according to claim 1, characterized in that: The method for establishing the target equivalent source electric field model in S2 is: The electrochemical impedance spectroscopy and polarization curves provide boundary conditions for the target equivalent source electric field model. In three-dimensional space, the Laplace equation satisfied by the equivalent source electric field distribution under different polarization conditions is as follows: Where, is the Laplace operator, and u(x,y,z) is a function of x, y, and z in three-dimensional space.

5. The method for simulating the electric field of underwater target excitation in air-sea ice-sea water according to claim 1, characterized in that: The boundary conditions provided by the material polarization feature in S2 are as follows: The linear polarization boundary is expressed as follows: Where J is the polarization current density, E is the polarization potential, E0 is the equilibrium potential, and R p is the linear polarization resistance; The nonlinear polarization boundaries are as follows: Where, j 0 is the corrosion current density, b a 、b c is the anode and cathode Tafel slope.

6. The method for simulating the electric field of underwater target excitation in air-sea ice-sea water according to claim 1, characterized in that: The potential V in S3 i The expression is as follows: In the above formula, V i (r,z) represents the potential value at a depth of z in the i-th layer of the medium, which is a distance r from the central axis of the cylindrical coordinate system; r represents the value in the depth direction, z represents the value in the radius direction, and λ represents the wave number in the wave number domain. represents the upward decay part of the potential, Indicates the downward attenuation part; zz i ≤0, U i and D i are coefficients determined by the boundary conditions, and J0 is the Bessel function of the first kind and order 0.

7. The method for simulating the electric field of underwater target excitation in air-sea ice-sea water according to claim 1, characterized in that: The calculation layer boundary Z is calculated in S3 i and the upper boundary Z i-1 The potential method is as follows: Layer boundary z = z i and the upper boundary z = z i-1 The potential is: Among them, V i (r,z i-1 ) is the layer i medium at the layer boundary z=z i-1 The potential at i-1 (r,z i-1 ) is the i-1th layer of medium at the layer boundary z=z i-1 The potential at i and D i Considered as layer boundary z=z i The coefficient just above, and Considered as layer boundary z=z i-1 The coefficients directly below, and thus: Where λ represents the wave number in the wave number domain, I is the excitation current, and u i =exp(-λh i ),u i represents the propagation coefficient of the i-th layer medium, h i is the thickness of the dielectric layer, J0 is the Bessel function of the first kind and order 0; Resistivity at the layer boundary z = z i-1 The boundary changes that occur require the following boundary conditions to be met: In i (r,z i-1 )=V i-1 (r,z i-1 ) Then we can get: r i-1 , t i-1 The layer boundaries z = z i-1 The reflection coefficient and transmission coefficient at , and satisfy: Among them, ρ i represents the resistivity of the i-th layer of medium, ρ i-1 Represents the resistivity of the i-1th layer medium.

8. The method for simulating the electric field of underwater target excitation in air-sea ice-sea water according to claim 1, characterized in that: The method for calculating the potential relationship when a point current source is placed in a layer in S3 is as follows: Set a virtual boundary, the upper layer is the first The layer below is the mth layer, and the depth of the point current source inside the layer is z=z c , since the reflection coefficient of this boundary is zero, we can get: Among them, u m =exp(-λh m ), ρ m represents the resistivity of the mth layer of medium, u m represents the propagation coefficient of the mth layer medium; The integral of the above Bessel function is filtered using the fast Hankel filter method, and the integral of the Bessel function on the interval (0, +∞) is recorded as g(r): J v It is the first kind Bessel function of order v, real number v>-1, and the transformation formula is introduced: Where u, v∈(-∞, +∞), u and v are new variables in the fast Hankel transform; r0 is a selected constant, and the following function is defined: Combining the above conditions, g(r) can be written as: Where G(v) is the function F and H v Convolution of H v =J v (e u )e u , is the convolution kernel function, which is used to convert the original integral into the convolution form; g(r) represents the result after fast Hankel filtering; f(λ) represents a part of the integrand, which represents the source term or known function related to the problem; Sampling F(u) using the sampling function P(x) = sin(πx) / πx and discretizing v yields: Where Δ<1 / |2f|, Δ is the sampling interval, f is the highest frequency of the sampling function; r0 is the constant used to scale the radial coordinates and wavenumbers in the fast Hankel transform; n is the index of the discrete sample point; m is another index in the discrete convolution; the fast Hankel transform filter coefficient H is v for: Where H v represents the fast Hankel transform filter coefficient; represents the processed fast Hankel transform filter coefficient; P represents the sampling function, and Δ represents the sampling interval.

9. An underwater target excitation electric field simulation system in air-sea ice-sea water, characterized in that: include: Establishing a corrosion polarization characteristic model unit for underwater metal target materials, which is used to establish a corrosion polarization characteristic model for underwater metal target materials; A target equivalent source electric field model unit is established based on the boundary conditions provided by the material polarization characteristics, and is used to establish the target equivalent source electric field model based on the boundary conditions provided by the material polarization characteristics; Establish an electric field model unit of an equivalent source in a low-temperature ambient air-sea ice-seawater medium to complete the following steps: Construct a cylindrical coordinate system with depth direction z and radius direction r; Determine the potential V at any location in the i-th layer generated by the point current source i expression; Calculate layer boundary Z i and the upper boundary Z i-1 The potential of Calculate the relationship between the potentials when a point current source is placed within the layer; The design of the three-layer resistivity model of air-sea ice-sea water has been completed. From the vertical direction from top to bottom, it is the air layer, sea ice layer, and sea water layer.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement the method for simulating the electric field of underwater target excitation in air-sea ice-sea water as described in any one of claims 1-8.

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