| People's life frequently inevitably receives natural disasters (for example: earthquake, landslide, etc), man-made disasters (terrorism, wars) as well as harmfulness comes from different kinds of accidents. Disasters make big destroy to people's life and wealth .When disasters of accident come, rescuing the stranded people in time relives the pain of families, the loss of country. So, it has great significance to carry out the research of advanced life rescue detection and orientation method.Our country is nearly blank in high-advanced techniques and methods of disaster rescue, especially techniques and methods of disaster rescue which are able to effectively solve the problem about lives or objects buried or blocked after disasters. It is urgent to do research on rescuing theory and tackle key problem of high-advanced rescuing technique. This paper is an important part of the project "Survey of Ultra-wide band Electromagnetic Method for Urban Disaster Rescue and Life Searching".The emergence of UWB electromagnetic pulse and the research which is about the theory of UWB electromagnetic pulse detection, orientation and sensing theory realizes the dream of life rescue. It has the following advantages when UWB technique is used in life rescue: the ability of high-accuracy tracking, high-accuracy orientation and high-accuracy communication; making up the deficiencies of other conventional life rescue methods(sound wave, vibration detection , searching canine); the detection of moving objects, objects behind obstacle in effect; the easy design of searching apparatus.Meanwhile, FDTD is widely used in electromagnetism field because of its advantages of good flexibility, fast speed, less memory, good simulation results and the gain of the response of wide band frequency after calculation for once .Therefore, to some degree, it is an optimized method to solve the problem about UWB.Based on Electromagnetic field and wave theory, this paper analyzes the characters of UWB electromagnetic pulse by the numbers, solves the difficulty about FDTD technique, involving: the stable conditions of numerical calculation, the improvement of differential method, the acceding of inspiration and the setting of strong absorbing boundary conditions etc. This paper shows perfect matched layer in detail and interior electromagnetic parameters setting, introduces and deduces the expressions of CPML-FDTD, at one time, solves the 2.5D problem in geologic structure based on PML-FDTD method. At last, we build up two-dimension forward model to do research on UWB Electromagnetic pulse propagation and imaging characters. Total research method makes up the deficiency of the searching and orientation methods, and explores the new field of application; it also provides gist for life rescue and effective search and orientation. The primary work in this thesis:1. The introduction and deduction of high-order FDTD difference method ,CPML absorbing boundary condition and applied for building up calculation models.2. The 2.5D-FDTD arithmetic which is less memory cost, fast speed ,easy to built up model and calculate is firstly build up and testified its possibility and correctness, also applied for solving 2.5D problem in geologic structure.3. Different simple 2D-FDTD geoelectric models are built up .By comparing UWB sources of different wave with wide-band sources of different wave testifies the high resolution of UWB pulse and analyzes the characters of imaging objects underground. |
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