Disclosure of Invention
Aiming at the defects of the prior art, the invention mainly aims at the difficult problem of numerical simulation of electromagnetic energy absorption by a human body in a complex electromagnetic environment, provides a hybrid method based on a consistency diffraction theory and a parallel multi-layer rapid multipole sub-algorithm, utilizes the consistency diffraction theory to simulate the complex electromagnetic environment, the electric field intensity of the position of the human body is obtained, the plane wave with the same electric field intensity is used for irradiating the human body, the electric field distribution inside the human body is analyzed by utilizing the parallel multi-layer rapid multipole sub-algorithm, and the specific absorption rate value (Specific Absorption Rate, SAR) inside the human body is calculated, so that the evaluation of electromagnetic energy absorption by personnel in a complex electromagnetic environment is realized.
The method comprises the steps of combining a consistency diffraction theory and a parallel multi-layer rapid multipole sub-algorithm to be applied to a complex electromagnetic environment, simulating the complex electromagnetic environment, analyzing electric field distribution in the human body according to the parallel multi-layer rapid multipole sub-algorithm, analyzing specific situations of energy absorption of personnel in the electromagnetic environment, simulating values of electromagnetic energy absorption of the human body in the complex electromagnetic environment, and providing reliable basis for evaluation of electromagnetic energy absorption of personnel in the complex electromagnetic environment.
The invention realizes the above purpose as follows:
(1) Establishing a complex electromagnetic environment geometric model;
(2) Performing surface subdivision on the complex electromagnetic environment geometric model by adopting a triangle unit to obtain an environment model grid discrete information file;
(3) According to the environment model grid discrete information, adopting a consistency diffraction theory to carry out electromagnetic simulation on the split model, and obtaining the electric field intensity at the position of the human body in the complex electromagnetic environment;
(4) Establishing a high-precision human body geometric model;
(5) Performing surface subdivision on the high-precision human body geometric model by adopting a triangle unit to obtain a human body model grid discrete information file;
(6) According to the electric field intensity obtained in the step (3), adopting plane waves with the same electric field intensity to irradiate the human body;
(7) According to the grid discrete information of the human body model, carrying out electromagnetic simulation on a high-precision human body geometric model by utilizing a parallel multi-layer rapid multipolar sub-algorithm to obtain electric field distribution inside the model;
(8) And calculating SAR (specific absorption rate) in the model by using electric field distribution in the human body geometric model to obtain SAR distribution of the whole human body model, namely, a numerical simulation result of electromagnetic energy absorption by the human body.
Compared with the prior art, the invention has the following advantages:
Firstly, the complex electromagnetic environment is simulated by adopting the consistency diffraction theory, so that the scene object with relatively simple electromagnetic attribute but relatively large area in the environment can be efficiently and accurately analyzed, the memory consumption in the analysis process is small, and the calculation speed is high;
secondly, the invention adopts the parallel multilayer rapid multipolar sub-algorithm to analyze the electric field distribution in the human body, so that the invention can accurately analyze the complex objects with large differences of electromagnetic properties of the medium of each organ and small occupied area in the internal environment of the human body, and can rapidly and accurately solve the electromagnetic field distribution of the complex medium in a small area;
Thirdly, the method comprehensively analyzes the electric field distribution of the human body under the condition of plane wave irradiation by combining the consistency diffraction theory and the parallel multilayer rapid multipole sub-algorithm, cooperatively realizes the evaluation of electromagnetic energy absorption by personnel in a complex electromagnetic environment, and the obtained simulation data of electromagnetic energy absorption by the human body in the complex electromagnetic environment is accurate and reliable.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
Referring to fig. 1, the implementation steps of the present invention are specifically as follows:
Firstly, establishing a complex electromagnetic environment geometric model.
The geometric model of the whole complex electromagnetic environment is built by using commercial software such as the three-dimensional full-wave electromagnetic simulation software FEKO, CST and the like, and the embodiment adopts the commercial software FEKO to build the complex electromagnetic environment which is composed of a plurality of buildings and comprises the ground and the superstructure as shown in fig. 2.
And secondly, carrying out surface subdivision on the geometric model of the complex electromagnetic environment.
In the embodiment, a complex electromagnetic environment geometric model is subjected to surface subdivision by adopting triangle units, and an environment model grid discrete information file is obtained, wherein the file at least comprises the following information of triangle unit numbers, vertex numbers and vertex coordinates of each triangle unit and material properties corresponding to each triangle unit. In this embodiment, the surface subdivision of the complex electromagnetic environment geometric model by using the triangle units is specifically that triangular grid units are selected in commercial software FEKO to spatially discrete the established complex electromagnetic environment geometric model, and the complex electromagnetic environment model is scattered into a limited number of triangle units, at this time, the complex electromagnetic environment model is divided into a limited number of triangle units, each triangle unit has own global number and vertex number, vertex coordinates and material properties, and the global number information of the triangle units, the vertex number information of each triangle unit, vertex coordinate information and material property information of each triangle unit are stored for use in electromagnetic simulation analysis of the consistency diffraction theory.
And thirdly, carrying out electromagnetic simulation on the split model by adopting a consistency diffraction theory according to the environment model grid discrete information to obtain the electric field intensity of the position of the human body in the complex electromagnetic environment, specifically calculating the electric field distribution value of the whole human body occupation area of the position of the human body in the complex electromagnetic environment, and simultaneously recording the electric field intensity vector of the point of the maximum electric field amplitude of the human body.
The electromagnetic simulation analysis method can be divided into a high-frequency method and a low-frequency method, wherein the common high-frequency method comprises a geometric optical method (GO), a geometric diffraction theory (GTD), a physical optical method (PO), a physical diffraction theory (PTD), a consistent diffraction theory (UTD), a bouncing ray method (SBR) and the like, the common low-frequency method comprises a time domain finite difference method (FDTD), a Finite Element Method (FEM), a moment method (MoM) and the like, and the high-frequency method has the advantages of high calculation speed, less required storage capacity and the like, but is not suitable for analyzing complex structures and media, and the low-frequency method has high calculation accuracy and is suitable for analyzing complex structures and media, but has low calculation speed and large memory consumption. Because the complex electromagnetic environment has the characteristics of large calculation area and relatively simple structure and medium properties, the electric field intensity E (r) at the position of the human body in the complex electromagnetic environment is calculated by adopting the consistent diffraction theory (UTD) in the embodiment.
Fourth, a high-precision human body geometric model is established.
As shown in FIG. 4, the high-precision human body geometric model is established based on data in a human anatomy database, wherein the data comprises main tissue organs of each part of a human body, such as brain, lung, heart, liver, kidney, skeleton, muscle, skin and the like, and the model of each tissue organ established in the method is a closed curved surface for facilitating the subsequent electromagnetic simulation by using a multi-layer rapid multipole sub-algorithm.
Fifthly, carrying out surface subdivision on the high-precision human body geometric model.
And carrying out surface subdivision on the high-precision human body geometric model by adopting triangle units to obtain a human body model grid discrete information file, wherein the file at least comprises the following information of triangle unit numbers, vertex numbers and vertex coordinates of each triangle unit and material properties corresponding to each triangle unit. In this embodiment, the surface subdivision of the high-precision human body geometric model is performed by using triangle units, specifically, triangular grid units are selected in commercial software FEKO to perform space dispersion on the established high-precision human body geometric model, the high-precision human body geometric model is dispersed into a limited number of triangle units, at this time, each tissue organ of the high-precision human body geometric model is divided into a limited number of triangle units, each triangle unit has own global number and vertex number, vertex coordinates and material properties, and the global number information of the triangle units, vertex number information of each triangle unit, vertex coordinate information of each triangle unit and material property information of each triangle unit are stored for use in parallel multi-layer rapid multipolar sub-algorithm analysis.
And sixthly, carrying out electromagnetic simulation on the split high-precision human body model by using a parallel multi-layer rapid multipolar sub-algorithm to obtain electric field distribution Ebody (r) inside the human body geometric model.
The multi-layer rapid multipole sub-algorithm is an acceleration algorithm of a moment method, has the advantage of high precision of the moment method, can greatly reduce the calculation complexity of the moment method, improves the calculation efficiency and reduces the calculation resource consumption. The invention further accelerates the multi-layer rapid multipole sub-algorithm by combining with a Message Passing Interface (MPI) parallel technology, thereby further improving the efficiency of electromagnetic simulation of the high-precision human body model.
When the parallel multi-layer rapid multipolar sub-algorithm is used for electromagnetic simulation of the high-precision human body model, the plane wave source is required to be adopted for illuminating the high-precision human body model, the electric field intensity vector of the plane wave source is equal to the electric field intensity vector obtained in the third step, meanwhile, the electromagnetic simulation is completed by combining the human body model grid discrete information, and the electric field distribution Ebody (r) inside the human body geometric model is obtained.
Seventh, the specific absorption rate SAR in the high-precision human body model is calculated by utilizing the electric field distribution Ebody (r) in the human body geometric model, the SAR distribution of the whole human body model is obtained, and the evaluation of electromagnetic energy absorption by personnel in a complex electromagnetic environment is realized.
The specific absorption rate SAR in the high-precision human body model is calculated by utilizing the electric field distribution Ebody (r) in the human body geometric model, and the calculation formula is as follows:
Wherein sigma is the conductivity of human tissue, the unit is S/m, ρ is the density of human tissue, and the unit is kg/m3,Ebody (r) represents the electric field at r inside the human model.
The effects of the present invention will be further described with reference to simulation experiments.
1. Simulation conditions:
The simulation experiment is carried out in a hardware environment of CPU main frequency 3.0GHz, memory 1TB, display card GTX1660 and hard disk 4TB and a software environment of windows10 and FEKO.
2. The simulation content:
establishing a complex electromagnetic environment model, wherein the whole area is formed by 5 buildings, and a parabolic antenna is arranged at the top of the leftmost building to radiate electromagnetic waves outwards as shown in fig. 2;
Firstly, analyzing electric field distribution of a sensitive area of a complex electromagnetic environment by adopting the method of the invention, wherein the electric field distribution of an area in front of an intermediate building is shown in fig. 3;
assuming that the human body is positioned at the maximum field intensity point in the sensitive area, recording the field intensity value at the point;
The method is used for establishing a high-precision human body geometric model as shown in fig. 4, irradiating a human body by using plane waves with the same electric field intensity based on the method, and analyzing the electric field distribution in the human body geometric model.
3. Simulation results:
The SAR distribution of the whole human body model is obtained through experiments, namely the simulation experiment result is shown in fig. 5, according to fig. 5, the numerical condition of electromagnetic energy absorption of each part of the human body in the complex electromagnetic environment can be clearly shown, and according to the result, the condition evaluation of electromagnetic energy absorption of personnel in the complex electromagnetic environment can be further realized. Therefore, the method can complete numerical simulation of electromagnetic energy absorption by personnel in a complex electromagnetic environment, and obtain specific and visual simulation data.
The simulation analysis proves the correctness and effectiveness of the method provided by the invention.
The non-detailed description of the invention is within the knowledge of a person skilled in the art.
The foregoing description of the preferred embodiment of the invention is not intended to be limiting, but it will be apparent to those skilled in the art that various modifications and changes in form and detail may be made without departing from the principles and construction of the invention, but these modifications and changes based on the idea of the invention are still within the scope of the appended claims.