α,β,γ滤波器的等效带宽

常增益滤波器具有运算简单,存储量少以及不需要事先知道测量噪声和模型噪声等优点,因此在实际工程中得到了广泛应用。由于在理论分析和工程应用中往往需要知道α,β,γ滤波器等效带宽,为此文中给出了计算α,β,γ滤波器等效带宽的方法。并分析了α、β、γ滤波器的频率特性。最后给出了等效带宽的多项式拟合公式,为工程应用提供了方便、快捷的计算滤波器等效带宽的方法。     

新型机电产品使用可靠性研究

在提出相似理论基本原理的基础上,着重介绍了权重值的计算方法,进而给出了系统相似度的概念和公式,并通过实例探讨了利用相似理论计算机电产品相似度精确值及预测新产品可靠性的方法,最后指出了在具体的计算过程中需要考虑的一些问题.     

V-I传输矩阵方法在布拉格光纤光栅分析中的运用

介绍了V-I传输矩阵方法用于布拉格光纤光栅的理论分析,该方法通过参量变换将相邻薄层间的界面矩阵退化为单位矩阵,从而大大提高了计算效率。从传输矩阵出发,数学上推导出耦合模方程,证明了该方法的正确性,有助于加深对V-I传输矩阵方法物理机制的理解。数值模拟分析发现V-I传输矩阵方法具有计算快速、简单明了的优点。最后还指出V-I传输矩阵方法仅适用于短周期光纤光栅,若要运用于长周期光纤光栅,需要进一步理论修正。     

基于Matlab GUI的模拟带通滤波器的设计

在传统的模拟带通滤波器设计过程中需要大量繁琐的数值计算,若手工计算则费时费力。在分析模拟带通滤波器设计理论和基于Matlab的图形用户界面（GUI）设计方法的基础上,利用Matlab GUI工具设计了具有通用性交互式切比雪夫模拟带通滤波器分析设计软件,并对软件中各控件回调函数的设计给出了详细的设计方法。用户只需要输入设计滤波器所需参数,然后选择相应的功能菜单,就可以得到滤波器的特性参数,并进行滤波器的性能分析。该设计解决了滤波器设计过程中大量繁琐的数值计算问题,为切比雪夫模拟带通滤波器的研究设计提供了有效的辅助工具。     

基于有限元的脉冲激光辐照材料温度场研究

在激光超声检测过程中,为了合理加载脉冲激光的能量,以便获得幅值较大的超声波信号,同时避免脉冲激光造成材料的损伤,需要对脉冲激光辐照材料的温升进行数值计算。依据有限元理论,建立脉冲激光辐照材料的有限元模型,结合导热微分方程,将脉冲激光以热流密度的形式加载于材料表面,分析材料表层受激光辐照时的温度场,讨论有限元热分析时网格尺寸的选取对分析结果的影响。给出了材料表层受脉冲激光辐照时温度场的计算方法和网格尺寸的选择依据,并利用温度场的理论解析结果和应力场分析结果分别验证了温度场有限元计算方法的正确性和有效性。     

基于传播算子的Root-MUSIC算法

传播算子（PM）法不需要进行复杂的特征值分解,减小了计算量,但仅在信噪比较高的情况下才有较好的波达方向估计性能,且谱峰搜索仍需要较大计算量。在此基础上提出了一种改进的算法PM-Root-MUSIC,它不需要特征值分解,同时用多项式求根代替谱峰搜索,大大减少了计算量。理论分析和计算机仿真结果表明此方法是有效的。     

短波网基于节点的抗毁性评估

给出了短波网基于节点的抗毁性定义和相应的评价方法。与通常的抗毁性评估方法相比,该方法简单有效,不需要大量复杂的计算。理论分析和实例均表明该方法是可行的。     

GPU计算及其在密码分析中的应用

文中研究了GPU计算及其在密码分析中的应用,详细分析了各自的特点和发展现状。GPU计算发展很快,具有运算密集型和高度并行的特点。密码分析的方法非常丰富,大多数方法都需要大规模的运算,而且密码运算本身也比较简单。通过理论分析并结合实例研究,发现GPU计算非常适合用于密码分析,可以大大提高密码分析特别是穷举攻击的效率。同时,也应拓宽GPU计算在密码分析中的应用,以用于更多的密码分析手段。     

WCDMA与PHS系统共存干扰分析与解决方案

本文结合3GPP、STD-28协议以及路测结果对WCDMA与PHS系统共存时无线环境干扰进行了理论计算分析,并利用PHS基站、手机杂散测试结果得出规避干扰需要的理论隔离度,就干扰判定方法以及滤波器安装准则进行了介绍.     

新型射线管分裂技术的计算效率研究

射线追踪的计算效率取决于射线管数量的大小,本文基于计算效率提出一种射线管分裂新技术——确定性射线管分裂法。通过与常见的两种射线追踪方法理论分析进行对比,给出需要追踪的射线管数量的解析式,表明该方法可以显著减少射线管数量。最后通过仿真计算验证了在相同追踪代数和预测精度条件下,确定性射线管分裂法具有花费CPU时间较少、计算效率较高的优点。     

波导加载腔的场计算

本文基于边界元法(BEM),提出了一种新的计算波导加载谐振腔的谐振频率、外Q值和场分布的数值计算方法。计算表明,用BEM来处理波导加载腔这样的开放系统,具有计算时间短、机器内存少和精度高等优点。     

波导混合模问题的修正边界元法分析

本文建立了分析波导混合模问题的修正边界元模型;导出了关于混合模的耦合边界积分方程组及其退化形式,并用矩量法将之离散为齐次代数方程组,从而得波导的混合模传输常数;最后以部分介质填充波导为例进行了计算,所得结果与横向谐振法结果吻合得很好。     

The combination method: a numerical technique forelectrocardiographic calculations

This paper presents a method for electrocardiographic and other bioelectric calculations combining the Green's function boundary integral technique with the finite element method. Both the boundary integral method and the finite element method have been used extensively in electrocardiography for calculating epicardial and torso potentials. The boundary integral method is well suited for finding potentials in regions of isotropic conductivity and is computationally efficient, requiring unknown potentials to be calculated on the bounding surfaces only. It also compares favorably in accuracy with the finite element method in those regions. The finite element method is used in solving for potentials in regions of anisotropic conductivity since no simplifying assumptions or transformations of anisotropic regions into isotropic regions before solution are required. Combining the two methods, using the boundary integral method in isotropic regions and the finite element method is anisotropic regions, allows the advantages of both methods to be exploited.     

计算波导加载腔外Q值的新方法

本文基于边界元法,提出了一种新的简单有效的计算速调管输出系统波导加载腔外Q值的方法。计算了一种矩形波导加载矩形谐振腔的常见结构。采用主模TEIO模式激励,端口处采用推导出的Robin—type边界条件,通过扫频方式求得系统谐振频率,利用等效电路法导出的公式计算出系统的外Q值。数值结果表明,利用边界元法计算波导加载腔这样的半开放系统,具有实现简单,计算精确度高数据输入少,计算时间短等优点。     

An application of the boundary element method to the magnetic fieldintegral equation

A boundary element method (BEM) for the solution of electromagnetic scattering problems using the magnetic field integral equation (MFIE) is discussed. The discretized form of the MFIE is written in indicial notation with no limitations placed on the order of either the geometric or functional approximation. By considering several different types of boundary elements, it is determined that geometric errors can be significant and degrade the accuracy of the numerical solution. It is shown that a higher-order approximation for the current could significantly improve the accuracy of the numerical solution. The superparametric boundary element in which the geometry was given quadratic approximation and the current was given linear approximation was more efficient than elements using lower-order approximations. The BEM results are compared to the results obtained using the dielectric bodies of revolution (DBR) code     

Asymptotic boundary conditions for finite element analysis ofthree-dimensional transmission line discontinuities

The finite element method is used to analyze open three-dimensional transmission line structures in the quasi-TEM regime. Starting from the general solution of the Laplace equation in spherical coordinates, a set of asymptotic boundary conditions are derived for three-dimensional quasi-static problems for a spherical outer boundary. The second-order boundary condition is generalized to a box-shaped outer boundary and implemented in the finite element method to solve the potential problem of a rectangular microstrip patch. Numerical results show that the asymptotic boundary conditions yield more accurate results than those obtainable with a perfectly conducting shield placed at the same location     

The computational performance of a high-order coupled FEM/BEMprocedure in electropotential problems

This paper presents a thorough analysis of the computational performance of a coupled cubic Hermite boundary element/finite element procedure. This C1 (i.e., value and derivative continous) method has been developed specifically for electropotential problems, and has been previously applied to torso and skull problems. Here, the behavior of this new procedure is quantified by solving a number of dipole in spheres problems. A detailed set of results generated with a wide range of the various input parameters (such as dipole orientation, location, conductivity, and solution method used in each spherical shell [either finite element or boundary elements]) is presented. The new cubic Hermite boundary element procedure shows significantly better accuracy and convergence properties and a significant reduction in CPU time than a traditional boundary element procedure which uses linear or constant elements. Results using the high-order method are also compared with other computational methods which have had quantitative results published for electropotential problems. In all cases, the high-order method offered a significant improvement in computational efficiency by increasing the solution accuracy for the same, or fewer, solution degrees of freedom.     

用边界元素法计算阶梯开口波导的反射系数

本文报道的是用边界元素法计算阶梯开口波导的反射系数。文中给出了用边界元素法求解波动方程问题的主要步骤和公式,并对本问题的一些计算细节作了说明。把在特殊状态下得到的结果与有关文献中的结果作了比较,从而看出这种方法的有效性。     

Closed-form expressions for the coupling capacitance of metal fill tiles in VLSI circuits

A new closed-form formula for the computation of the coupling capacitance of metal tiles is presented in this work. It exploits the analytical solution of the Laplace equations of equivalent studied problems. Comparative results are given with two commercial tools employing the boundary element method (BEM) and the finite element method (FEM). The results show that the capacitance value computed by the proposed formula is in close agreement to the value obtained by the simulators.     

Eliminating interior resonances in finite element-boundary integralmethods for scattering

A modification in the implementation of the finite-element-boundary-integral method is proposed for eliminating the interior cavity resonances. It is demonstrated that by using the scattered rather than the total field as the system variable, and by introducing a small loss in the propagation constant associated with the boundary integral equation, internal resonance effects are eliminated. Results are presented for two-dimensional problems with the finite element mesh terminated on a circular enclosure