| In recent years, with rapidly increasing in functionality of the electronic information systems, the electromagnetic environment they have to face becomes more and more complex and harsh. With the development of electromagnetic pulse weapons, the great attention is paid on the electromagnetic compatibility (EMC) and electromagnetic interference (EMI) problems. High-power electromagnetic pulses can be injected through the antennas, wires, cables, and etc. which will cause the electronic devices malfunction and even damaged. In particular, for the ship platform, a number of transceivers in different bands have to be placed in the limited space. So it is of vital important to deeply investigate the coupling mechanism and damage effects of high-power electromagnetic pulses on typical devices and systems. In the study of EMC problems for the ship platform, there are great restrictions on the field measurement due to the required strict testing conditions and cost of resources. Under such circumstance, the numerical simulation is able to play a key role in design evaluation, quantification and improvement of EMC problems. In this dissertation, we focus on the hybrid and fast algorihms based on time domain integral equation (TDIE), and develop the parallel computational platform for the analysis of transient electromagnetic problems under the illumination of electromagnetic pulses. The main research and academic contributions of this dissertation are summarized as follows:1) Based on the properties of time domain integral equation, firstly, the method of moment for solving the frequency domain integral equation is introduced. Further, the complete derivation of the time-domain integral equation is given, and the marching-on-in-time (MOT) scheme for solving TDIE is studied step by step. The commonly used temporal basis functions are discussed, then the explicit and implicit MOT schems are investigated. Three forms of TDIE formulations, incluindg electric field integral equation, magnetic field integral equation and combined field integral equations are analyzed, respectively.2) Due to the late time instability of marching-on-in-time scheme, the marching-on-in-degree (MOD) scheme is proposed, and it is proven to be very late time stable. The novel temporal basis function based on Laguerre polynomials is introduced, then the formulations and process of MOD for anaysing metallic and dielectric structures are derived and explained in detail. Further, an adaptive MOD scheme based on2-norms is developed, which improves the computation efficiency of MOD.3) The electromagnetic characteristics of dielectric-metallic composite structures are studied, and the TD-EFIE-PMCHW formulations are derived. Different circumstances are taken into account, incluing dielectric coating, metallic patch, and etc. A compact and effective treatment of junctions among dielectic, metallic component and free space is proposed. The technique of accelerating the convolution in MOD recursion is studied.4) The hybridization of TDIE and high frequency method, and TDIE-TDPO hybrid method are proposed. For solving the muti-scale problems, the target is divided into TDIE region and TDPO region, according to the respective advantages of the two methods. Compared to the full TDIE solution, the hybrid method reduces the calculation consumption. TDIE-TDPO method is utilized to analyze the coupling characteristics of multiple antennas on the platform.5) The adaptive integral method is studied systematically. Based on this, the TD-AIM-MOD fast algorithm is proposed. In the implementation of TD-AIM-MOD method, several techniques are adopted, such as fast solution of projection matrix based on auxiliary basis function, the Toeplitz matrix-vector multiplication accelerated by FFT, sparse matrix storage and sparse matrix-vertor multiplication. Due to reduce the memory requirement of the near field correction matrix, the technique of singular value decomposition compression is introduced.6) The parallel TD-AIM-MOD fast algorithm is developed.4-D spatial-temporal FFT is solved by parallel. Numerical examples are provided to analyze the parallel efficieny of the proposed algorithm.7) Some typical modern ship mast structures are studied, and the required modeling techniques for electromagnetic simulation are also investigated. Further, a series of tower mast structures for simulation are established by using3ds Max and HFSS. Numerical simulations are given to analyze the transient scattering characteristics of these typical ship mast structures by using the proposed parallel TD-AIM-MOD fast algorithm.In addition, in this dissertation, the surface current display, fast solution of equations formed by Vandermode matrix, singular and nearly singular integral are studied. They together improve the capabilities of TDIE method for solving large-scale electromagnetic problems. |
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