共查询到20条相似文献,搜索用时 78 毫秒
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Chen Xiaoguang Nie Zaiping 《电子科学学刊(英文版)》1998,15(2):158-167
The paper adopts finite element method to analyze the forward problem of low-frequency current fields in inhomogeneous media. Firstly, the direct solution of 2-D and 3-D scalar potential is given. Secondly, the technique of covering finite elements for problems with movement has been presented; namely, when the place of testing point moved, the meshing data will be produced automatically to avoid re-meshing and distortion of the mesh. Thirdly the free and prescribed potential method is used to make the finite element coefficient matrices. Then this paper provides the result of a validity test obtained by simulating the laterolog-3 logging, compared with the numerical model-matching method. Finally, the MLL response is calculated. 相似文献
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Several kinds of waveguide components such as curved waveguide bends, arbitrary angle waveguide bends and T-junctions have been analyzed with boundary element method in this paper. A new discretization method for the boundary element method to solve the waveguide discontinuities has been given. The numerical results obtained agree well with the experimental results and numerical results in other literature. Especially, the scattering characteristics of Forded E-, H-plane T-junctions in 3mm band have been analyzed using boundary element method and the calculation results are presented. 相似文献
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本文综述了非均匀介质中场与波理论近年来的研究进展及其应用成果,着重介绍了非均匀介质中的电磁场正演分析和反演计算中的各种高效数值方法,以及它们在电法测井数值模拟和成象研究中的成功应用。 相似文献
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用修正玻昂迭代法重建复杂介质结构 总被引:5,自引:2,他引:3
着重阐述了将修正玻昂迭代法结合高效的数值模式匹配法用于感应测井中的反演与剖面成象。首先利用玻昂近拟将非线性问题线性比,然后应用吉洪诺夫正则化与迭代方法求解电磁场的积分方程。 相似文献
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Often in the analysis of electromagnetic field problems reducible to Laplace's equation in two dimensions, solution is required for only a few points. A numerical method which is applicable to the solution of such problems, provided that the boundary is circular, is given. Excellent results have been obtained also for some cases with piecewise-linear boundaries. 相似文献
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相量感应线圈系地层识别能力的改善 总被引:1,自引:1,他引:0
相量感应测井的关键在于同时精确测量R信号和X信号,利用相量反褶积反演地层参量。本文采用自适应滤波法对线圈系在平面成层介质中的响应场进行快速求解;基于几何因子理论用最小平方滤波法设计出了相量反褶积中的三个滤波因子。对模拟地层反演计算结果表明,在较大的电导率范围内,基本上消除趋肤效应影响,有效地改善了线图系的薄地层识别能力。 相似文献
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On failure recoverability of client-server applications in mobile wireless environments 总被引:1,自引:0,他引:1
Chen I.-R. Baoshan Gu George S.E. Sheng-Tzong Cheng 《Reliability, IEEE Transactions on》2005,54(1):115-122
Analytical results for the Cdf of the failure recovery time for client-server applications in mobile wireless environments characterized by logging, and mobility handoff strategies for facilitating failure recovery are reported in the paper. The results can be applied to determine if a mobile application can satisfy its recoverability requirement upon a mobile host failure when operating under a set of parameter values characterizing the mobile application, the underlying client-server environment, and the logging & mobility handoff strategies adopted by the mobile application. Model parameters which affect the shape of the failure recovery time Cdf for two mobility handoff strategies, namely, Eager and Lazy, are identified, and their effects are analyzed, with numerical data and result interpretations given. A tradeoff analysis between the cost invested by these two mobility handoff strategies for maintaining the logging and checkpoint information before failure versus the return of investment in terms of improved failure recoverability is given, and the best checkpoint interval period that would yield the best return of investment for the eager mobility handoff strategy over the lazy strategy is identified. 相似文献
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Ke Lu 《Microwave Theory and Techniques》1997,45(1):9-14
The analytical solution of an ideal linear varied nonuniform transmission line (LNTL) has been obtained and the exact linear two-port ABCD matrix of LNTL has been given correctly for the first time. By using cascaded LNTL sections to approximate an arbitrary characteristic impedance profile, a new technique has been presented in this paper for analyzing an arbitrary nonuniform transmission line (NTL). The technique is far better than the conventional technique in terms of the computational accuracy and intensity since it uses a piecewise-linear characteristic impedance profile in place of the stepped profile used by the conventional technique. Several numerical examples have been given to demonstrate the method 相似文献
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建立了槽区内加载介质的格栅慢波结构模型.通过Borgnis函数法和场匹配法得到冷态和热态色散方程.并推导了耦合阻抗的表达式.在稀疏电子注的假设下,求得增益近似解的表达式.通过数值方法,求解并分析了加载介质对色散关系、基波耦合阻抗、基波相速和基波增益的影响.并指出分别在槽内加载介质和格栅对侧加载介质对高频特性的不同影响趋势. 相似文献
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多层介质覆盖矩形微带天线谐振频率的精确计算 总被引:4,自引:1,他引:3
本文将谱域导抗法推广应用于计算多层介质覆盖矩形微带天线的谐振频率,通过引入两种特殊的数值积分方法,解决了二维振荡函数无穷区间积分问题,获得了一些有用的结论。 相似文献
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Modified Latin Hypercube Sampling Monte Carlo (MLHSMC) Estimation for Average Quality Index 总被引:2,自引:0,他引:2
The Monte Carlo (MC) method exhibits generality and insensitivity to the number of stochastic variables, but it is expensive for accurate Average Quality Index (AQI) or Parametric Yield estimation of MOS VLSI circuits or discrete component circuits. In this paper a variant of the Latin Hypercube Sampling MC method is presented which is an efficient variance reduction technique in MC estimation. Theoretical and practical aspects of its statistical properties are also given. Finally, a numerical and a CMOS clock driver circuit examples are given. Encouraging results and good agreement between theory and simulation results have thus far been obtained. 相似文献
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电磁散射问题的Neumann级数解 总被引:1,自引:0,他引:1
本文利用算子方程的Neumann级数解法来研究无限长金属柱体的低频散射问题。我们分别研究了E波和H波入射时金属柱体散射问题的级数解法,并给出大量计算实例.这种级数解法的优点在于频率较低时收敛快且不涉及矩阵的求逆运算.金属柱体上的表面电流分布可通过简单的求和运算而得到,从而节约了大量计算时间. 相似文献
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Electrostatic potential, carrier densities and space charge density distributions have been calculated using an iterative scheme for linearly graded p-n junction. It is found that the results obtained from this scheme are close to those given by rigorous numerical formulations, especially at applied forward bias. As an application of this scheme the charge-defined emitter space-charge-layer transit time has been calculated and results compared with those of numerical algorithms. 相似文献
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分段线性取样鉴相频率合成器的混沌现象 总被引:2,自引:0,他引:2
本文从理论上分析了取样锁相式频率合成器混沌的产生机理和产生条件,探讨了奇异吸子的相空间轨迹及其演变规律,通过计算机模拟给出了以T为岔参数的分岔图和混沌区域随系统参数的变化曲线。 相似文献
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Tao Qing Zaiping Nie Shiquan He Xianzheng Zong 《Journal of Infrared, Millimeter and Terahertz Waves》2012,33(9):963-971
The numerical method of the Integral Equation has been used to model the electromagnetic excitation, transmission, and radiation problems of the beam waveguide. The Mode Matching Method has been used to describe the impedance matching situation at the exciting aperture of the waveguide. The excitation conditions were established based on the expansion of the waveguide modes and the continuity of the tangential components of the fields. The volume-surface integral equations combined with the equavalence principle have been used to model the wave transmission in the beam waveguide. The numerical solutions of the electromagnetic transmission and aperture radiation of the waveguide have been given by using the Multilevel Fast Multipole Algorithm (MLFMA). It has been demonstrated that the method proposed by this paper is able to provide the efficient and accurate numerical solution for the excitation, propagation and radiation problems of the beam waveguide with arbitrary shape and electrically large size. 相似文献
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多区域柱面分层介质中的电磁散射—电磁波测井分析 总被引:7,自引:3,他引:4
本文讨论了径向柱面分层介质中全波分析的解析模式和数值模式方法.前者适用于任意激励形式下的场分析;后者在轴对称激励时,通过引入反射矩阵和透射矩阵的概念,可求解二维完全非均匀介质中的场.基于数值模式匹配理论,编制了适用于电磁波测井的计算机分析程序.通过实例计算,获得了与二维有限元方法完全一致的结果。而计算时间仅后者的1%. 相似文献