单轮电机失效时四轮轮毂电动汽车各驱动模式转向特性研究

本文在对轮胎侧偏特性和轮胎力研究的基础上,提出了四轮轮毂电动汽车四种驱动模式的转向力矩分配问题。通过数学分析,将此问题转化为一个有约束条件的最优化求解问题,接着使用MATLAB优化工具箱,并采用有效集算法对此优化问题进行求解,最终解决了单轮电机失效时四种驱动模式的选择问题,为改善单轮电机失效时四轮轮毂电动汽车的转向特性,防止车辆侧滑失稳提供了理论依据。最后采用汽车动力学仿真软件TESIS DYNAware对所提理论的正确性进行了仿真验证。     

确定微型圆柱腔回音廊模式共振峰位置的方法

本文介绍了微型圆柱腔中回音廊模式共振峰位置的两种确定方法,即数值计算法和解析近似公式求解法。用两种方法对回音廊模式的共振峰位置进行了计算比较,结果表明:精确的数值计算结合简便的解析近似公式求解方法,为快速、精确地确定回音廊模式的共振峰位置提供了一种方便和可靠的途径。     

开孔金属腔屏蔽效能快速算法适用性评估

对开孔金属腔屏蔽效能（SE）的四种快速算法传输线等效电路法、EMT法、ILCM法、Modal-MOM法的适用性进行评估,为不同实际工程问题选用恰当的算法提供了依据。为了解决传统SE结果描述方法不适用于快速算法适用性评估的问题,采用绝对误差和曲线相关系数这两个参数,提出SE随金属腔和孔缝尺寸单独变化的Contour图描述方法。在此基础上,利用864组不同形状、尺寸矩形金属腔的SE计算结果,分析并确定了四种SE快速算法满足不同计算精度时适用的腔体模式数。结果表明,在同等计算精度条件下,Modal-MOM算法可适用的腔体模式数最多,ILCM算法次之,而传输线等效电路法适用腔体模式数最少,这些结果为实际工程应用提供了指导。     

二维泊松方程的遗传PSOR改进算法

针对二维泊松方程在实际应用过程中几种常用方法存在计算量大、易发散、局部收敛等不足,提出了一种改进算法.该算法基于并行超松弛迭代法,采用遗传算法对松弛因子进行全局寻优,解决了超松弛迭代法求解泊松方程时最佳松弛因子难以确定的问题.构建了多目标适应度函数,优化了遗传算子参数,分析了算法的计算量、计算时间与误差精度,与传统方法进行了对比研究.结果表明:松弛因子对泊松方程求解的速度与精度影响显著;改进算法能减少迭代次数,节省计算时间,加快方程的求解;算法适合于求解计算量较大、精度要求较高的时域有限差分方程,而且精度要求越高,算法的性能越好,节省的时间也越多.     

量子计算加速的解法器算法及应用综述

量子计算作为一种基于量子力学原理的全新计算模型,具有强大的并行性和潜在的颠覆性影响力,为解决复杂问题提供了新的思路。本文的主要目标是对量子计算在大规模科学与工程计算领域中数值计算问题的解法器算法和应用进行综述。重点介绍量子计算在线性方程组、特征值问题、微分方程、哈密顿量与图计算、量子机器学习、量子解法器平台以及实际数值模拟等领域的具体应用。针对不同的数值计算问题,详细讨论当前主流的量子计算算法,并总结近年来国内外相关算法的研究进展。最后,对量子计算在数值计算求解相关研究方向的未来发展趋势进行展望。     

数字散斑相关方法亚像素求解的一种混合方法

亚像素求解是数字散斑相关方法(DSCM)中最重要的技术。亚像素求解算法的精度和效率直接影响DSCM的精度和计算速度。目前广泛应用的两种亚像素求解方法在处理高质量散斑图时都存在一定的缺陷:基于灰度插值的散斑场亚像素恢复方法,其计算精度较高,但计算消耗太大;基于相关系数分布的拟合方法,其计算消耗小,但计算精度较低。在分析两种亚像素求解方法各自优缺点的基础上,提出了一种结合两种算法优势的混合算法。混合算法在保证亚像素求解精度的基础上,可以大大降低整个算法的计算消耗。     

同伦正则化算法求解多宗量瞬态热传导反问题

以Bregman距离函数作为正则化泛函,建立了多宗量瞬态热传导反演的一种求解模式,可对导热系数和边界条件等进行联合识别.时域上采用精细算法进行离散,并应用同伦算法进行求解.对信息的测量误差和初值选取作了初步探讨,并进行了数值验证.     

二维声场预测的快速多极基本解法

传统基本解法在二维大规模模型的声场求解过程中,系统方程形成和求解的计算量正比于自由度N的二次方O(N2)和三次方O(N3),求解效率低;为此,引入快速多极子算法并采用广义极小残差法迭代求解,提出一种用于二维声场预测的快速多极基本解法。对无限长圆柱体及二维类车体辐射模型的仿真结果表明,当N为3000时,分别采用快速多极基本解法与传统基本解法求解所需的时间比值约为百分之四,且N越大比值越小;最终实现系统方程的形成和求解的计算量降低到正比于自由度O(N),提高了对二维大规模模型声场预测计算效率。      

计算机控制光学抛光驻留时间求解中两类优化算法的分析

建立了基于矩阵计算的驻留时间计算模型,根据实际加工要求建立了最小二乘和最佳一致逼近最优化求解数学模型,总结了两类优化问题的求解方法。根据自研数学解法器,利用数值计算分析了这两类算法的计算特点。仿真结果显示,两种自研算法具有较高的计算精度,最小二乘逼近算法计算效率有待提高,对外界扰动和计算模型等误差不敏感,最佳一致逼近算法计算效率较高,但对误差比较敏感。实际加工时,如果面形精度已经比较高时,建议多采用最小二乘逼近算法。     

常压DBD二维流体模型的FCT方法数值模拟

根据常压介质阻挡放电流体模型的物理方程,采用固定网格有限差分算法,分别用四阶和六阶相位误差FCT方法模拟求解二维流体连续方程.在均匀的初始条件下研究放电雪崩过程中电子密度的时空演化,具体分析和比较两种算法的差异.FCT方法模拟求解得出的计算结果与气体放电理论吻合较好,是一种具有较好的准确性和高精度的算法.     

Application of an improved subpixel registration algorithm on digital speckle correlation measurement

Digital speckle correlation method (DSCM) has been widely used in experimental mechanics to obtain the surface deformation fields. One of the challenges in practical applications is how to obtain the high accuracy with far less computation complexity. To determine the subpixel registration of the DSCM, a high efficient gradient-based algorithm is developed in this paper. The principle is described and four different modes of the algorithm are given. Based on computer-simulated images, the optimal mode of the algorithm is verified through the comparison of computation time, optimal subset-region size and sensitivity of the four modes. The influences of speckle-granule size and speckle-granule density on accuracy are studied and a quantitative estimation of the optimal speckle-granule size range is obtained. As the applications of this method, the practical deformation measurements with the rigid body translation and rotation as well as an experiment on biomechanics are presented to certify the feasibility and the validity of the algorithm.     

Fast convergence and higher-order mode calculation of optical waveguides: perturbation method with finite difference algorithm

We present an efficient algorithm for determining mode eigenvalues as well as field distributions of optical waveguides with two-dimensional transverse refractive index profile. The algorithm is devised with the analytical perturbation correction method combined with the finite difference approximation of Helmoltz's equation. The technique is simple and does not involve solving any eigenvalue equation or matrix formalism. The algorithm reduces abruptly the computation time required for the field convergence to mode, and can calculate any higher-order modes without the need of any pre-conditioning the field w.r.t. waveguide geometry, or calculation of previous order modes and/orthogonalization. The analysis can yield precisely both scalar and polarized modes. By applying it to waveguide problems whose solutions are otherwise known, the efficacy of the method has been established.     

A search-and-track algorithm for controlling the number of guided modes of planar optical waveguides with arbitrary refractive index profiles

A search-and-track algorithm is proposed for controlling the number of guided modes of planar optical waveguides with arbitrary refractive index profiles. The algorithm starts with an initial guess point in the parameter space that supports a specific number of guided modes. Then, it searches for, and tracks, the boundaries of this space or another space supporting different number of modes. It does so by monitoring the sign of a unified cutoff dispersion function. The algorithm is applied to both symmetric and asymmetric silicon-based parabolic-index waveguides. It shows that unlike asymmetric waveguides, the single-mode condition of symmetric waveguides is controlled by TM-, as opposed to TE-, polarization. This abnormal polarization control is strongest for high index contrast waveguides of sub-micrometer core sizes. The results are verified by full-vectorial beam propagation method.     

多值测试诊断策略优化设计

针对电子系统中多值测试条件下的测试排序问题,提出了一种诊断策略优化方法。首先,以相关性矩阵模型为基础,将已有的二值测试的优化算法同多值测试问题相结合,提出了适用于多值测试的基于霍夫曼编码的启发式函数;其次,将平均测试代价最小和平均测试步骤最少作为优化目标,采用与或树启发式搜索算法生成诊断树,得到多值测试的诊断策略,并给出了诊断策略优化方法的具体实现步骤;最后,将其应用到航空设备的实例中。结果表明提出的基于霍夫曼编码的与或树启发式搜索算法是可行的,其生成的诊断树是最优的,比基于信息熵的与或树启发式搜索算法具有更小的平均测试代价和更少的平均测试步骤。     

Simple design of an edge-emitting diode laser for preventing spatial multimoding via thermal lensing

The parameters of a diode-laser structure composed of a pair of built-in high-index regions for providing stable, single-spatial-mode operation to high cw powers are numerically found. A three-dimensional numerical code has been implemented that takes into account carrier diffusion in the quantum well and thermal lensing. The laser characteristics are calculated as functions of the above-threshold drive level. Within the simulation, higher-order optical modes on a "frozen background" are computed via the Arnoldi algorithm. Then, for a 6-μm-wide low-index core and 2-3-mm-long devices, stable single-mode operation up to multiwatt-level (2-3 W) cw output power is predicted.     

A Simple Bi-directional Mode Expansion Propagation Algorithm Based on Modes of a Parallel-plate Waveguide

The bi-directional mode expansion propagation algorithm (BEP) is known to be an accurate and efficient method for modelling field distribution in high-index contrast waveguide structures with strong back-reflections like Bragg gratings and photonic crystals. The main difficulty of this method is that for lossy structures, the propagation constants of modes are to be searched in the complex plane. To speed-up this procedure, a two-step algorithm for eigenmode calculation based on the expansion into the modes of an empty metallic waveguide has recently been proposed. Proper truncation rules possessing good convergence of the expansion method for both TE and TM modes have also been recently published. In this contribution, both these approaches are combined in the development of an extremely simple version of the two-dimensional BEP method that makes use of the field expansion into the eigenmodes of a parallel-plate waveguide. The method is strictly reciprocal and appeared to be computationally reliable also for strongly lossy structures. High numerical stability is ensured using the scattering matrix formalism, and an efficient method of calculating Bloch modes for symmetric as well as asymmetric periodic waveguide structures is adopted. A wide range of applicability of the method is demonstrated by a few examples.     

使用改进的有限分析解方法模拟流体分离流动

在这篇文章里,我们提出了一种改进的有限分析解算法,它能够避免复杂的指数运算和级量求和,节省大量的计算时间,并能在同样的网格尺寸条件下,具有模拟比原算法高20倍以上雷诺数的流体流动问题的能力。对分离流的数值实验表明:对同样的雷诺数,这种算法能得到和原算法非常一致的计算结果。而高雷诺数下的数值结果也是令人满意的。     

微加工薄膜变形镜本征模分析

 介绍了变形镜本征模的构造过程及其特点，分析了从荷兰OKO公司购买的37单元微加工薄膜变形镜的本征模，并用前65阶Zernike多项式分析微加工薄膜变形镜的37阶本征模的特性。搭建了以微加工薄膜变形镜作为波前校正器、变形镜本征模为波前复原控制算法以及高分辨率Shack-Hartmann波前传感器为波前探测器的自适应光学实验系统。实验结果表明：变形镜本征模可以实现模式筛选，也可作为自适应光学系统的波前复原算法。