Ship magnetic field accumulation forecasting method and device under external magnetic field environment change condition

Abstract

The invention discloses a ship magnetic field accumulation forecasting method and device under an external magnetic field environment change condition, and relates to the technical field of magnetic detection forecasting, and the ship magnetic field accumulation forecasting method under the external magnetic field environment change condition mainly comprises the steps: changing an external magnetic field according to a rule, and obtaining a simulated hysteresis loop through a micro-magnetokinetic equation; obtaining magnetic calculation parameters according to the simulated hysteresis loop and the actually measured hysteresis loop; and obtaining an induced magnetic field curve forecasting result by using the magnetic calculation parameters and the micro-magnetic kinetic equation according to the external magnetic field at each moment of the simulated sailing path. According to the ship magnetic field accumulation forecasting method and device under the external magnetic field environment change condition, the ship magnetic field change under the external magnetic field environment change condition can be forecasted.

Description

Technical Field

[0001] The present invention relates to the field of magnetic detection and prediction technology, and more specifically, to a method and device for predicting the accumulation of a ship's magnetic field under conditions of a changing external magnetic field environment. Background Art

[0002] With the continuous expansion of the navigation range of modern ships and the increasing diversity of the geographical magnetic field environment involved, the real-time magnetic field status and distribution around ships will become more and more complex.

[0003] Metallic ships are ferromagnetic, while the Earth's magnetic field is weak, typically much smaller than the saturation field of the ship's materials. Traditional finite element methods involving magnetic fields cannot simulate the magnetic properties of materials below the saturation field. Therefore, existing technologies cannot predict how a ship's magnetic field will change under the cumulative influence of the Earth's magnetic field.

[0004] Based on micromagnetism, according to the smallest magnetic unit - spin and the movement of single electron spin under the action of magnetic field, the interaction between multiple spins, the magnetic domain composed of multiple spins, the interaction between multiple magnetic domains, and the changes of magnetic domains under the action of external field, it provides the possibility of simulating the accumulated induced magnetic field changes of specific magnetic target systems under the action of weak environmental magnetic field. How to provide a method for predicting the accumulation of ship magnetic field under the condition of changing external magnetic field environment is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and device for predicting the accumulation of ship magnetic fields under conditions of changes in the external magnetic field environment, which can predict the changes in the ship magnetic field under conditions of changes in the external magnetic field environment.

[0006] The present invention provides a method for predicting the accumulation of a ship's magnetic field under conditions of a changing external magnetic field environment, comprising the following steps: S1: simulating a regularly changing external magnetic field, and according to the regularly changing external magnetic field, using a micromagnetodynamic equation to obtain a simulated hysteresis loop; S2: obtaining magnetic calculation parameters based on the simulated hysteresis loop and a measured hysteresis loop; S3: according to the external magnetic field at each moment of a planned navigation path, using the magnetic calculation parameters and the micromagnetodynamic equation to obtain a prediction result of an induced magnetic field curve.

[0007] Furthermore, step S1 specifically includes: simulating a regularly changing external magnetic field, changing the external magnetic field according to the regularity, and using the micromagnetic dynamics equation to obtain a simulated hysteresis loop, such as the formula: = H ext , , , , , , , in, 、 、 is the unit vector in the x, y, and z directions in the Cartesian coordinate system, 、 、 are the components of the magnetic moment in the x, y, and z directions of the Cartesian coordinate system, is the magnetic moment at grid i, is the Zeeman energy contributed by the external magnetic field, is the vacuum permeability, M is the magnetization vector, and Hext is the external magnetic field; is the demagnetization energy, 、 and are the demagnetization factors in the x, y, and z directions, respectively. is the saturation magnetization of the material; is the exchange energy between adjacent spins, A is the exchange factor, where i and j represent the two neighboring spins; is the magnetic anisotropy energy, is the first-order anisotropy constant term, is the unit vector of the anisotropy principal axis direction, is the total energy density, Represents the effective magnetic field vector in the magnetic material system.

[0008] Furthermore, step S2 specifically includes: testing the actual sample using a large external magnetic field to obtain a measured hysteresis loop; comparing the simulated hysteresis loop with the measured hysteresis loop based on key parameters to obtain magnetic calculation parameters; the key parameters include saturation magnetic induction intensity B_s, remanence B_r and coercive force H_c.

[0009] The present invention also provides a ship magnetic field accumulation prediction device under the condition of changing external magnetic field environment, and the device includes the following modules: a hysteresis loop simulation module, configured to simulate the regularly changing external magnetic field, and obtain a simulated hysteresis loop based on the regularly changing external magnetic field using the micromagnetodynamic equation; a magnetic calculation parameter module, configured to obtain magnetic calculation parameters based on the simulated hysteresis loop and the measured hysteresis loop; an induced magnetic field curve prediction module, configured to obtain an induced magnetic field curve prediction result based on the external magnetic field at each moment of the planned navigation path using the magnetic calculation parameters and the micromagnetodynamic equation.

[0010] Furthermore, the hysteresis loop simulation module is specifically configured to simulate a regularly changing external magnetic field, change the external magnetic field according to the regularity, and use the micromagnetic dynamics equation to obtain a simulated hysteresis loop, such as the formula: = H ext , , , , , , , in, 、 、 is the unit vector in the x, y, and z directions in the Cartesian coordinate system, 、 、 are the components of the magnetic moment in the x, y, and z directions of the Cartesian coordinate system, is the magnetic moment at grid i, is the Zeeman energy contributed by the external magnetic field, is the vacuum permeability, M is the magnetization vector, and Hext is the external magnetic field; is the demagnetization energy, 、 and are the demagnetization factors in the x, y, and z directions, respectively. is the saturation magnetization of the material; is the exchange energy between adjacent spins, A is the exchange factor, where i and j represent the two neighboring spins; is the magnetic anisotropy energy, is the first-order anisotropy constant term, is the unit vector of the anisotropy principal axis direction, is the total energy density, Represents the effective magnetic field vector in the magnetic material system.

[0011] Furthermore, the magnetic calculation parameter module is specifically configured as follows: using a large external magnetic field to test the actual sample to obtain a measured hysteresis loop; according to key parameters, the simulated hysteresis loop and the measured hysteresis loop are compared to obtain magnetic calculation parameters; the key parameters include saturation magnetic induction intensity B_s, remanence B_r and coercive force H_c.

[0012] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the ship magnetic field accumulation prediction method under the above-mentioned external magnetic field environment change condition are implemented.

[0013] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the program, the steps of the above-mentioned method for predicting the accumulation of ship magnetic fields under the condition of changes in the external magnetic field environment are implemented.

[0014] The present invention also provides a computer program product, comprising a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for predicting the accumulation of ship magnetic fields under conditions of changes in the external magnetic field environment.

[0015] The method and device for predicting the cumulative magnetic field of a ship under the condition of a changing external magnetic field environment provided by the present invention have the following beneficial effects: The present invention is based on micromagnetism and begins with the smallest magnetic unit, the spin. It studies the motion of a single electron spin under a magnetic field, the interaction between multiple spins, the magnetic domains composed of multiple spins, the interaction between multiple magnetic domains, and the changes in magnetic domains under the action of an external field. Ultimately, it simulates the changes in the induced magnetic field accumulated by a specific magnetic target system under the action of a weak ambient magnetic field. Utilizing the Landau-Lifshitz-Gilbert kinetic equation in conjunction with the finite difference method, and taking into account magnetic parameters such as different magnetic domain structures and different magnetic anisotropies, the magnetization process of the magnetic domain and macroscopic magnetism is simulated and calculated. This is a numerical simulation of the changes and predictions of magnetic phenomena. This invention applies the micromagnetic research method to the prediction of the cumulative changes in the magnetic field of a ship under the conditions of changing external magnetic field environment for the first time, solving the problem that the magnetic field characteristics of magnetic targets under the changing weak environmental magnetic field cannot be numerically calculated. It can reflect the internal magnetic distribution state and inherent magnetic characteristics of ship materials, effectively combine the simulation results with the experimental results, and can predict the changes in the magnetic field of the ship, solving the problem that the surrounding magnetic field cannot be predicted during the ship's navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which: Figure 1 This is a flow chart of the method for predicting the accumulation of ship magnetic fields under the condition of changing external magnetic field environment provided by the present invention; Figure 2 It is a schematic diagram of a complete hysteresis loop of the Hrange simulation provided by the present invention; Figure 3 This is a hysteresis loop result diagram of a micromagnetic simulation calculation under certain magnetic parameter conditions provided by the present invention; Figure 4This is a schematic diagram of the spin magnetization orientation distribution of a certain magnetic domain model micro-region provided by the present invention; Figure 5 It is the accumulated induced magnetization intensity in the Z direction of the ship after experiencing a specific environmental magnetic field change provided by the present invention; Figure 6 It is the accumulated X-direction induced magnetization intensity of the ship after experiencing a specific environmental magnetic field change provided by the present invention; Figure 7 This is a flowchart of ship magnetic field accumulation prediction under the condition of external magnetic field environment changes provided by the present invention; Figure 8 It is a structural block diagram of the computer device provided by the present invention. DETAILED DESCRIPTION

[0017] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0018] Figure 1 A schematic diagram of a method for predicting the cumulative magnetic field of a ship under conditions of a changing external magnetic field environment is shown. In this embodiment, the method for predicting the cumulative magnetic field of a ship under conditions of a changing external magnetic field environment includes the following steps: S1: simulate the regular change of the external magnetic field, change the external magnetic field according to the regular change, and use the micromagnetodynamics equation to obtain the simulated hysteresis loop; In an exemplary embodiment, step S1 specifically includes: simulating a regularly changing external magnetic field, changing the external magnetic field according to the regularity, and using a micromagnetic dynamics equation to obtain a simulated hysteresis loop, such as the formula: = H ext , , , , , , , in, 、 、 is the unit vector in the x, y, and z directions in the Cartesian coordinate system, 、 、 are the components of the magnetic moment in the x, y, and z directions of the Cartesian coordinate system, is the magnetic moment at grid i, is the Zeeman energy contributed by the external magnetic field, is the vacuum permeability, M is the magnetization vector, and Hext is the external magnetic field; is the demagnetization energy, 、 and are the demagnetization factors in the x, y, and z directions, respectively. is the saturation magnetization of the material; is the exchange energy between adjacent spins, A is the exchange factor, where i and j represent the two neighboring spins; is the magnetic anisotropy energy, is the first-order anisotropy constant term, is the unit vector of the anisotropy principal axis direction, is the total energy density, Represents the effective magnetic field vector in the magnetic material system; As an exemplary embodiment, in step S1, parameters such as the exchange interaction coefficient, anisotropy coefficient, and saturation magnetization intensity of the ferromagnetic material are preset, and the hysteresis loop of the system under the saturation magnetization condition of a large magnetic field of ±1000Gs is simulated and calculated using the micromagnetic dynamics equation; As an exemplary embodiment, the preset exchange coefficient is 30E-12 (J / m), the anisotropy coefficient is 500000 (J / m 3 ), the maximum saturation magnetization is 8E5 (A / m); assuming that a specific magnetic domain model is selected, when the external magnetic field changes regularly, the aforementioned formula is substituted to calculate the magnitude of the induced magnetic field under the corresponding external magnetic field, and the corresponding hysteresis loop curve is obtained by connecting the induced magnetic fields calculated under different external magnetic fields; As an exemplary embodiment, the process of simulating changes in the external magnetic field is as follows: The regularly changing external magnetic field is shown in Table 1: Table 1: Regularly changing external magnetic field data

[0019] According to the typical magnetization process of the hysteresis loop and combined with the Hrange data, the simulation of the change of the external magnetic field H can be divided into four stages, simulating the dynamic process of the ferromagnetic material undergoing a complete hysteresis loop: the unit is Gauss Gs, where 100 points are taken in each stage: Stage 1: Forward initial magnetization (H from 0 → +10000); Path description: The external magnetic field H increases monotonically from the initial zero value to the positive saturation magnetic field intensity H_s=+10000; Corresponding to the hysteresis loop stage: rising along the initial magnetization curve, the magnetic induction intensity B increases rapidly with H until it reaches the saturation value B_s; Physical meaning: The magnetic domains in the ferromagnetic material gradually align along the direction of the external field, and the magnetization tends to saturation; Stage 2: Reverse demagnetization to negative saturation (H from +10000 → -10000); Path description: The external magnetic field H decreases monotonically from positive saturation +10000 to negative saturation -10000; Corresponding hysteresis loop stages: (1) Demagnetization stage (H from +10000 → 0): B decreases along the hysteresis loop to the remanence B_r (B is not equal to 0 when H=0); (2) Reversal magnetization stage (H from 0 → -10000): Applying a reverse magnetic field causes B to drop to zero (coercivity is H_c point), and then reverse magnetization to -B_s (reverse saturation); Physical meaning: The magnetic domain begins to flip in the opposite direction, and the intrinsic coercive force H_c of the material must be overcome to completely demagnetize; Stage 3: Forward remagnetization (H from -10000 → +10000); Path description: The external magnetic field H increases monotonically from the reverse saturation -10000 to the forward saturation +10000.

[0020] Corresponding hysteresis loop stages: (1) Reverse demagnetization (H from -10000→0): B recovers to zero along the reverse remanence -B_r (reverse coercivity -H_c point); (2) Forward remagnetization (H from 0→+10000): B rises again along the initial magnetization curve to B_s, completing the loop closure; Physical meaning: The magnetic domain undergoes reverse reversal and then arranges itself in the positive direction again, forming a closed hysteresis loop; Stage 4: Forward demagnetization (H from +10000→0); Path description: The external magnetic field H decreases monotonically from positive saturation +10000 to zero; Corresponding to the hysteresis loop stage: B drops along the hysteresis loop to the remanent magnetization B_r, at which point the material still retains its magnetism after the external field is removed; Physical significance: Verify the remanent magnetic properties of the material and reflect its ability to remember the magnetic field; The complete hysteresis loop simulated by Hrange is shown in Figure 2 As shown, its characteristics are: path irreversibility: the magnetization and demagnetization paths are separated to form a closed loop; key parameters include remanence B_r, coercivity H_c, saturation magnetic field H_s and saturation magnetic induction intensity B_s; among which remanence B_r is the residual magnetic induction intensity when H=0, and coercivity H_c is the reverse magnetic field required to make B=0; energy loss: the area enclosed by the hysteresis loop represents the hysteresis loss; S2: obtaining magnetic calculation parameters according to the simulated hysteresis loop and the measured hysteresis loop; In an exemplary embodiment, step S2 specifically includes: The actual sample is tested using a large external magnetic field to obtain a measured hysteresis loop; the simulated hysteresis loop is compared with the measured hysteresis loop based on key parameters to obtain magnetic calculation parameters; the key parameters include saturation magnetic induction intensity B_s, remanence B_r and coercivity H_c; As an exemplary embodiment, in step S2, the calculated hysteresis loop result is compared with the measured hysteresis loop result of the same material; and various magnetic calculation parameters that are consistent with the actual situation are determined; For an exemplary embodiment, the curve calculated by the formula simulation is compared with the hysteresis loop result of a real sample under an actual large external magnetic field (such as 10000Gs). If the B_s, B_r, and H_c values of the two are close, the preset model is considered correct and the subsequent calculation will continue with the model. S3: according to the external magnetic field at each moment of the planned navigation path, using the magnetic calculation parameters and the micromagnetic dynamics equation, obtain the prediction result of the induced magnetic field curve; As an exemplary embodiment, in step S3, after determining various calculation parameters, the spin states of the spins at different positions in the system will change under the influence of the external magnetic field. The changes in the magnitude and direction of the environmental magnetic field during navigation are substituted into the calculation results of the magnetization intensity of the magnetic target in various directions under the change of the external field. For an exemplary embodiment, the nautical chart information is consulted, and according to the intended navigation path, the size of the external magnetic field at each moment is obtained. The size of the external magnetic field is made into the Hrange array form in step S2, and the model determined in step S2 is used and substituted into the formula to calculate the curve result of the induced magnetic field.

[0021] In some embodiments, the above-mentioned method for predicting the accumulation of magnetic field of a ship under the condition of changing external magnetic field environment can also be implemented in the following manner. In this embodiment, the method for predicting the accumulation of magnetic field of a ship under the condition of changing external magnetic field environment includes: presetting the exchange interaction coefficient, anisotropy coefficient, saturation magnetization intensity and other parameters of the ferromagnetic material, and simulating the hysteresis loop of the system under the condition of large magnetic field ±1000Gs saturation magnetization through the micromagnetic dynamics equation, such as Figure 3 As shown in the figure, the calculated hysteresis loop results are compared with the measured hysteresis loop results of the same material; various magnetic calculation parameters that are consistent with the actual situation are determined; after determining the various calculation parameters, the spin states of the spins at different positions in the system will change under the action of the external magnetic field, such as Figure 4 As shown in the figure, the changes in the size and direction of the environmental magnetic field during navigation are substituted into the numerical calculation results of the magnetization intensity of the magnetic target in various directions under the condition of external field changes, and the possible range of changes of the ship's magnetic field in the environment is predicted.

[0022] It should be noted that when a single spin is in an ideal environment with no boundary conditions, infinity, and magnetic insulation, it will flip along the direction of a suddenly applied weak external magnetic field. However, in reality, even in a magnetically shielded environment, the spin will be affected by a variety of physical factors. For example, most magnetic materials have magnetocrystalline anisotropy. When the magnetocrystalline anisotropy is strong and the external magnetic field is weak, unlike the situation under ideal conditions, the application of the external magnetic field will not have any effect on the direction of the system's spin magnetization. That is, when the external magnetic field is not large enough to compete with the system's anisotropy, changes in the external magnetic field will not have any effect on the system's intrinsic magnetism, nor will there be any cumulative effect. The magnetocrystalline anisotropy of the material comes from the interaction between atoms in the crystal. The electron spin and the electron orbit will produce a coupling effect. The difference in the electron motion orbit in different directions will cause the spin magnetization energy in that direction to be different. Similarly, the neighboring atomic exchange interaction related to the symmetry of the crystal structure will also lead to different magnetization energies in different directions. The magnetocrystalline anisotropy is expressed by the following formula:

[0023] in, is the magnetic anisotropy energy, K is the anisotropy constant, is the angle between the magnetization direction and the principal axis of the crystal; in simpler crystals, the contribution of higher-order terms is weak, and often only the first-order anisotropy constant term needs to be considered. The role of It is not zero. A weak external magnetic field has little effect on the magnetization direction of the spin. Only when the magnetic field is strong enough will the magnetization direction of the spin flip along the external magnetic field. The critical threshold reached by the magnetic field is called the critical external field. For a simple model with a single magnetic domain, the critical external field can be expressed as follows:

[0024] in, is the critical external field strength, is the saturation magnetization of the material, is the vacuum permeability, take 𝑚 / A ; In addition to the influence of the crystal's own magnetocrystalline anisotropy, the direction of the magnetic moment of the actual material system is also affected by the shape of the material. The existence of the magnetic dipole-dipole field causes the energy of the magnetic moment in a specific direction to be higher. The specific demagnetization energy is in the form of:

[0025] The values of Nx, Ny, and Nz are closely related to the specific shape of the material. For materials of a specific shape and size, their specific values can be calculated based on theoretical formulas. For example, for a ship hull, due to the small in-plane demagnetization factor, the magnetic moment tends to be in the plane of the hull, which corresponds to a lower demagnetization energy. In addition, the presence of demagnetization energy tends to cause the material magnetization to form a non-uniform structure. The above considerations mainly consider the influence of anisotropy, namely the interaction between spins and the demagnetization field caused by the crystal field and the symmetry of the material structure, but have not yet taken into account the influence of the exchange interaction between spins. In reality, the magnetism of ships is ferromagnetic, and there is a strong interaction between neighboring spins. When the influence of the interaction between spins is considered, the magnetic field required to flip a group of spins is usually larger than the magnetic field required to flip a single spin. The exchange energy formula between adjacent spins is as follows:

[0026] Where A is the exchange factor, i and j are the two nearest neighbor spins, and m represents the magnetic moment. For ferromagnetic material systems, the exchange factor A is positive, meaning that when adjacent magnetic moments are in the same direction, it corresponds to the lowest energy state, indicating that the exchange interaction tends to uniformly magnetize the material. Therefore, when no external field is considered, due to the competition between demagnetization energy, magnetocrystalline anisotropy, and exchange energy, multiple magnetic domains will form within the magnetic material. In other words, in real-world situations, magnetic targets often have a large number of magnetic domains with complex domain structures. Similarly, considering the anisotropy of the spin anisotropic magnetic domain i, the anisotropy energy is:

[0027] in, is the magnetization unit vector; combining the effects of the above-mentioned microscopic spin magnetic fields, the total energy density is:

[0028] That is, the main field to be considered is the external field , exchange field , anisotropic field and demagnetization field ; The above are the main contributions to the micromagnetodynamics equation. In order to calculate and solve the differential equation, it is necessary to discretize space or time and use the finite difference method to solve it. Spatial discretization divides the study area into multiple cubic grids, and assumes that the interior of each grid is homogeneous and uniform. The magnetic moment at the grid is expressed as Representative, is the variable with solution;

[0029] in, represents the effective magnetic field vector, which describes the integrated magnetic field acting on the magnetic moment in the magnetic material in the magnetic system; Vacuum permeability is a physical constant used to describe the properties of the magnetic field in a vacuum. Its value is approximately ; Saturation magnetization refers to the magnetization intensity of a magnetic material when it is magnetized to a saturation state in a strong magnetic field; Here represents an arbitrary energy term of the system, which is related to the magnetic moment component 、 、 function; 、 、 They are the magnetic moments in the Cartesian coordinate system 、 、 Directional component; 、 、 In the Cartesian coordinate system 、 、 The unit vector of the direction; the formula as a whole is through the energy By taking partial derivatives of the magnetic moment components and combining them with the vacuum permeability and saturation magnetization, the components of the effective magnetic field in each direction are calculated, thereby determining the effective magnetic field vector. This formula is often used to study the magnetic properties of magnetic materials, such as magnetic domain structure and magnetization reversal. x, y, and z represent the components in three directions. Substituting them into the equations for calculating the effective magnetic field, the differential approximation method is used to solve them. For each time derivative of the magnetization vector Calculation is performed using the forward difference method: , , In an exemplary embodiment, as shown in Table 2, the input parameters of the micromagnetic simulation method are as follows: the parameters A, K, and Ms are configured as follows: Figure 5 The figure shows the accumulated Z-direction induced magnetization intensity of the ship after experiencing a specific environmental magnetic field change; Figure 6 The figure shows the accumulated X-direction induced magnetization intensity of the ship after experiencing a specific environmental magnetic field change; Table 2 Initial parameter configuration table of micromagnetic model

[0030] Figure 7This is a flowchart for predicting the cumulative magnetic field of a ship under varying external magnetic field conditions. According to the calculation results of this method, after a magnetic target experiences a series of weak external magnetic field changes, different changes accumulate in different magnetization directions. For example, the system's magnetization intensity in the Z direction remains relatively weak at 126 A / m, while the X direction is relatively strong at 1,284,220 A / m. This method can forward-calculate and predict the cumulative magnetic field changes of a ship based on different Earth environmental magnetic fields and the initial state of the magnetic target.

[0031] This embodiment provides a device for predicting the accumulation of ship magnetic fields under conditions of changing external magnetic field environments. The device includes the following modules: a hysteresis loop simulation module, configured to simulate regularly changing external magnetic fields, and obtain a simulated hysteresis loop using a micromagnetodynamic equation based on the regularly changing external magnetic fields; a magnetic calculation parameter module, configured to obtain magnetic calculation parameters based on the simulated hysteresis loop and the measured hysteresis loop; and an induced magnetic field curve prediction module, configured to obtain an induced magnetic field curve prediction result based on the external magnetic field at each moment of the planned navigation path using the magnetic calculation parameters and the micromagnetodynamic equation.

[0032] As an exemplary embodiment, the hysteresis loop simulation module is specifically configured to simulate a regularly changing external magnetic field, change the external magnetic field according to the regularity, and obtain a simulated hysteresis loop using the micromagnetic dynamics equation, such as the formula: = H ext , , , , , , , in, 、 、 is the unit vector in the x, y, and z directions in the Cartesian coordinate system, 、 、 are the components of the magnetic moment in the x, y, and z directions of the Cartesian coordinate system, is the magnetic moment at grid i, is the Zeeman energy contributed by the external magnetic field, is the vacuum permeability, M is the magnetization vector, and Hext is the external magnetic field; is the demagnetization energy, 、 and are the demagnetization factors in the x, y, and z directions, respectively. is the saturation magnetization of the material; is the exchange energy between adjacent spins, A is the exchange factor, where i and j represent the two neighboring spins; is the magnetic anisotropy energy, is the first-order anisotropy constant term, is the unit vector of the anisotropy principal axis direction, is the total energy density, Represents the effective magnetic field vector in the magnetic material system.

[0033] As an exemplary embodiment, the magnetic calculation parameter module is specifically configured as follows: using a large external magnetic field to test an actual sample to obtain a measured hysteresis loop; based on key parameters, the simulated hysteresis loop and the measured hysteresis loop are compared to obtain magnetic calculation parameters; the key parameters include saturation magnetic induction intensity B_s, remanence B_r and coercive force H_c.

[0034] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When executed by a processor, the computer program implements the steps of the aforementioned method for predicting the accumulation of a ship's magnetic field under conditions of a changing external magnetic field environment. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD). The storage medium may also include a combination of the aforementioned types of memory.

[0035] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the above-mentioned method for predicting the accumulation of magnetic fields of ships under the condition of changes in the external magnetic field environment are implemented.

[0036] like Figure 8As shown, the computer device 120 may include: at least one processor 121, such as a central processing unit (CPU), at least one communication interface 123, a memory 124, and at least one communication bus 122. The communication bus 122 is used to enable communication between these components. The communication interface 123 may include a display and a keyboard. Optionally, the communication interface 123 may also include a standard wired interface or a wireless interface. The memory 124 may be a high-speed random access memory (RAM) or a non-volatile memory, such as at least one disk drive. The memory 124 may optionally be at least one storage device located remote from the processor 121. The memory 124 stores application programs, and the processor 121 invokes program code stored in the memory 124 to execute any of the aforementioned method steps. The communication bus 122 may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, for example. The communication bus 122 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 8The fact that only one line is used in the figure does not mean that there is only one bus or only one type of bus. Memory 124 may include volatile memory, such as random-access memory (RAM); it may also include non-volatile memory, such as flash memory, a hard disk drive (HDD), or a solid-state drive (SSD); or it may include a combination of these types of memory. Processor 121 may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and an NP. Processor 121 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof. Optionally, the memory 124 is further configured to store program instructions. The processor 121 may call the program instructions to implement the ship magnetic field accumulation prediction method under the condition of a changing external magnetic field environment as in this embodiment.

[0037] This embodiment provides a computer program product, including a computer program. When the computer program is executed by a processor, the steps of the above-mentioned method for predicting the accumulation of magnetic fields of a ship under the condition of a changing external magnetic field environment are implemented.

[0038] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for predicting ship magnetic field accumulation under the condition of changing external magnetic field environment, characterized in that: The following steps are involved: S1: simulate the regular change of the external magnetic field, change the external magnetic field according to the regular change, and use the micromagnetodynamics equation to obtain the simulated hysteresis loop; S2: obtaining magnetic calculation parameters according to the simulated hysteresis loop and the measured hysteresis loop; S3: According to the external magnetic field at each moment of the proposed navigation path, the magnetic calculation parameters and the micromagnetic dynamics equation are used to obtain the prediction result of the induced magnetic field curve.

2. The method for predicting ship magnetic field accumulation under the condition of external magnetic field environment change according to claim 1, characterized in that: Step S1 specifically includes: simulating a regularly changing external magnetic field, changing the external magnetic field according to the regularity, and using the micromagnetic dynamics equation to obtain a simulated hysteresis loop, such as the formula: = H ext ， ， ， ， ， ， ， in, 、 、 is the unit vector in the x, y, and z directions in the Cartesian coordinate system, 、 、 are the components of the magnetic moment in the x, y, and z directions of the Cartesian coordinate system, is the magnetic moment at grid i, is the Zeeman energy contributed by the external magnetic field, is the vacuum permeability, M is the magnetization vector, and Hext is the external magnetic field; is the demagnetization energy, 、 and are the demagnetization factors in the x, y, and z directions, respectively. is the saturation magnetization of the material; is the exchange energy between adjacent spins, A is the exchange factor, where i and j represent the two neighboring spins; is the magnetic anisotropy energy, is the first-order anisotropy constant term, is the unit vector of the anisotropy principal axis direction, is the total energy density, Represents the effective magnetic field vector in the magnetic material system.

3. The method for predicting ship magnetic field accumulation under the condition of external magnetic field environment change according to claim 1, characterized in that: Step S2 specifically includes: testing the actual sample using a large external magnetic field to obtain a measured hysteresis loop; comparing the simulated hysteresis loop with the measured hysteresis loop based on key parameters to obtain magnetic calculation parameters; the key parameters include saturation magnetic induction intensity B_s, remanence B_r and coercive force H_c.

4. A ship magnetic field accumulation prediction device under the condition of changing external magnetic field environment, characterized in that: The device comprises the following modules: A hysteresis loop simulation module is configured to: simulate a regularly changing external magnetic field, change the external magnetic field according to the regularity, and obtain a simulated hysteresis loop using a micromagnetic dynamics equation; A magnetic calculation parameter module is configured to obtain magnetic calculation parameters according to the simulated hysteresis loop and the measured hysteresis loop; The induced magnetic field curve prediction module is configured to obtain the induced magnetic field curve prediction result based on the external magnetic field at each moment of the planned navigation path using the magnetic calculation parameters and the micromagnetic dynamics equation.

5. The device for predicting ship magnetic field accumulation under changing external magnetic field environment according to claim 4, characterized in that: The specific configuration of the hysteresis loop simulation module is as follows: simulate the regular change of the external magnetic field, change the external magnetic field according to the regular change, and use the micromagnetic dynamics equation to obtain the simulated hysteresis loop, such as the formula: = H ext ， ， ， ， ， ， ， in, 、 、 is the unit vector in the x, y, and z directions in the Cartesian coordinate system, 、 、 are the components of the magnetic moment in the x, y, and z directions of the Cartesian coordinate system, is the magnetic moment at grid i, is the Zeeman energy contributed by the external magnetic field, is the vacuum permeability, M is the magnetization vector, and Hext is the external magnetic field; is the demagnetization energy, 、 and are the demagnetization factors in the x, y, and z directions, respectively. is the saturation magnetization of the material; is the exchange energy between adjacent spins, A is the exchange factor, where i and j represent the two neighboring spins; is the magnetic anisotropy energy, is the first-order anisotropy constant term, is the unit vector of the anisotropy principal axis direction, is the total energy density, Represents the effective magnetic field vector in the magnetic material system.

6. The device for predicting ship magnetic field accumulation under changing external magnetic field environment according to claim 4, characterized in that: The magnetic calculation parameter module is specifically configured as follows: using a large external magnetic field to test the actual sample to obtain a measured hysteresis loop; based on key parameters, the simulated hysteresis loop is compared with the measured hysteresis loop to obtain magnetic calculation parameters; the key parameters include saturation magnetic induction intensity B_s, remanence B_r and coercive force H_c.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for predicting the accumulation of ship magnetic fields under the condition of changes in the external magnetic field environment as described in any one of claims 1 to 3 are implemented.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the ship magnetic field accumulation prediction method under the condition of changing external magnetic field environment are implemented as described in any one of claims 1-3.

9. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for predicting the accumulation of ship magnetic fields under the condition of changes in the external magnetic field environment described in any one of claims 1 to 3 are implemented.

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