一种三次均匀B样条曲线快速反算的方法

提出了均匀三次B-spline曲线反算的快速算法。在Matlab中编程实现,大大降低了程序的复杂性,提高了运算效率,并使重构所得曲线的两个端点处曲率不为零,满足了一阶连续,并给出了应用实例。     

高阶PSK调制的比特软信息简化计算方法

本文针对采用Gray映射的高阶PSK调制,提出一种比特软信息的简化计算方法.该方法利用Gray码的对称性,通过递推求取比特软信息.分析和仿真结果表明,在高阶调制下,此方法较传统的ML和Max-Log计算方法,运算负担大大降低且对系统性能影响不大.此外,该方法可对不同调制阶数的PSK信号统一处理,适合应用于自适应编码调制系统.     

A simplified bit metric calculation method for high-order PSK

This paper proposes a simplified bit metric calculation method for high-order PSK signal with Gray-mapping. This method calculates the bit metric recursively by the symmetry of Gray code. Analysis and simulation results show that the proposed method can significantly reduce the computational complexity and maintain similar performance compared to ML and Max-Log bit metric. Additionally, this method generates bit metrics of PSK signals with different modulation order in the same way, so it can be applied to adaptive modulation system.     

Least square method for the calculation of elastic constants

In this paper, a feasible formula is derived and simplified from least square method to calculate the elastic constants of materials. The simplified equation is identical to the stress and strain fluctuation formula obtained from statistical thermodynamics when the expression of the stress is redefined. It endues the formula with the theoretical validity. On the other hand, the convergence of the formula could be investigated via the theory of numerical analysis. Compared to the traditional fluctuation formula, the new technique shows better universality in the elastic bath method. Results obtained with a nearest-neighbor Lennard-Jones fcc crystal indicate that at low temperature the convergence of the formula is the same as the previous stress and strain fluctuation formula but the symmetry of the elastic constants is improved.     

Asymptotic expansions of results of the boundary integral equation method for plane elastostatic problems

The accuracy of numerical results can be improved by extrapolation if the asymptotic expansion of the error for step sizes (or element lengths) h tending to zero is well-known. In this paper expansions are determined for results of an integral equation for the plane elastostatic problem with prescribed boundary tractions. Special care is paid to discontinuous derivatives of the boundary values and of the boundary itself. Furthermore, the influence of the degree of interpolation of the sought function of the integral equation and the influence of non-equidistant division of the boundary on the structure of the expansion is investigated.The paper represents a continuation and partly a completion of [1].An extensive survey of the paper is given at the end of Section 1.     

VANET中一种链路稳定度的计算方法

在车用自组织网络VANET中,由于移动节点运动速度快且移动受道路拓扑约束等影响,导致链路容易断裂。路由选择是实现VANET的关键技术之一,没有高效的路由选择算法,VANET就无法工作,链路稳定度是衡量路由算法性能的重要因素。基于概率思想提出一种链路稳定度的计算方法来衡量链路的健壮性及可靠性。实验结果表明,所提出的链路稳定度计算方法是一种适合VANET场景的计算方法。     

An efficient hybrid reduction method for time-delay systems using Hermite expansions

This paper presents an efficient model reduction method for time-delay systems in the time domain. We expand the systems under a Hermite polynomial basis and show that Hermite coefficients of the expansion are determined by a linear equation, thus can be calculated efficiently. Such linear relationship is well taken in the projection methods of model reduction, and reduced models are generated to preserve a desired number of Hermite coefficients in the time domain, in contrast to other existing techniques which aim at approximating the transfer function of time-delay systems in the frequency domain. We also exploit two-sided projections for time-delay systems, leading to a hybrid reduction method which generates reduced models sharing the nice properties both in the time and frequency domains. Two numerical examples illustrate the feasibility and effectiveness of the approach.     

大分子蠕动的Monte Carlo模型及计算方法

高分子链分子量巨大而且分散,结构复杂多变,存在大量不确定的问题,给理论和实验研究造成许多困难。本文建立了一种基于高分子Monte Carlo模拟算法,分析分子蠕动阻力的模型。用链动力学法构造8配位点键长涨落格子链多链体系,通过高分子链的运动使任意的初始有序态演化到平衡态,可同时获得体系的动态和静态性质。将重要性抽样法和高分子多链体系的链动力学构造法,在键长涨落模型中结合起来,形成多链体系的链动力学求解法。引入空格扩散算法,用以研究高浓度态的高分子体系。统计平衡后元胞内高分子多链体系在链动力学算法作用下蠕动失败机率,对高聚物多链体系内分子蠕动的困难程度的定量模拟,能更直观分析高分子玻璃化转变的现象。     

A note on series expansions for multivariable root-loci

It is shown that the asymptotic behaviour of the infinite zeros and corresponding eigenvectors of a uniform rank multivariable system S(A, B, C) can be characterized by analytic functions of the complex variable. The results could be used for systematic numerical approximation of the asymptotic behaviour of the root-locus in cases where direct calculation of the root-locus is impractical     

Accurate calculation method for the capacitance of generalized circular structures

The generalized circular structures imply combinations of concentric strip rings with various potentials. The rectangular boundary division method is extended to estimate the total electric field energy from which the capacitance is effectively calculated. Numerical results based on this method are compared with other available numerical results and experimental data.     

一种采用泛进制计算法进行求解密钥的方法

文章通过分析RSA和椭圆曲线加密过程及算法,概括性地介绍了一种非线性加密解密方法——泛进制法。文章给出了一个泛进制算法公式,同时也给出了非线性多密钥方法。由于参数的增加,加大了非法用户破解运算难度,提高了信息安全性。     

基于R CN N的问题相似度计算方法

在搜索引擎、问答系统中利用深度学习的方法计算问题相似度是NLP领域研究的热点.结合卷积神经网络(CNN)和长短记忆网络(LSTM),提出了递归卷积神经网络(RCNN)问句相似度的计算方法,首先利用双向递归神经网络提取上下文信息,然后采用1D卷积神经网络将词嵌入信息与上下文信息进行融合;再利用全局最大池化提取关键信息来完...     

一种Lyapunov指数算法及其实现

提出了一种利用周期轨道不同权重计算Lyapunov指数的算法。对混沌序列的周期轨道进行统计，并计算不同的周期轨道的Lyapunov指数，依据周期轨道的权重加权求和得到整个混沌吸引子的平均Lyapunov指数。深入讨论了初始值等对平均Lyapunov指数的影响。该算法不用舍去开始迭代点，适用于复杂混沌系统。     

A fast quasi-multiple medium method for 3-D bem calculation of parasitic capacitance

A quasi-multiple medium (QMM) method is proposed to accelerate the boundary element method (BEM) for the 3-D parasitic capacitance calculation. In the QMM method, a homogeneous dielectric is decomposed into a number of fictitious medium blocks, each with the same permittivity of original medium. By the localization character of BEM, the QMM method makes great sparsity to the coefficient matrix of the overall discretized BEM equations. Then, using storing technique of sparse matrix and iterative equation solvers, the sparsity is explored to greatly reduce CPU time and memory usage of BEM computation. The computational complexity of the QMM accelerated BEM for a single-medium model problem is analyzed, and it is concluded as O(N), if the number of iterations is bounded. Numerical results verify the theoretical analysis and show the accelerating efficiency of the QMM method for calculation of 3-D parasitic capacitance.     

A new calculation method for the worst case tolerance analysis and synthesis in stack-type assemblies

Productivity and industrial product quality improvements entail a rational tolerancing process to be applied as early as product design. Once functional conditions are defined, an optimal specification for each component in a mechanical system is to be developed. Despite numerous studies in this area, the problem is still far from solved. It may be decomposed into two stages: development of specifications based on standards, or qualitative synthesis, and calculation of tolerances. To the extent that these two sets of problems are related, we propose to address them in parallel. In this paper, we present an original method that enables us to solve these two problems for the case of serial assembly (stacking) without clearances. This method is based on the use of influence coefficients to obtain the relationship between the functional tolerance and the tolerances associated with the geometry of the mechanism’s interface surfaces. We will describe a calculation algorithm that helps obtain influence coefficients solely from the assembly’s geometric definition. Then, we will show that under our working hypothesis, this relationship is piecewise linear.     

A geometrical workspace calculation method for cable-driven parallel manipulators on minimum tension condition

In this paper, a geometrical expression to delineate the sum of tensions (i.e. minimum 1-norm tensions) of 2-DoF planar cable-driven parallel manipulators (CDPMs) is proposed and proofed, which can be used to reduce calculation time of workspace determination. Furthermore, this paper also presents a systematic analysis on the relation between cable tension and workspace by means of convex analysis. In order to obtain wrench-feasible workspace, a unified and feasible algorithm is adopted in simulation examples of spatial CDPMs with different configurations, which demonstrate that the proposed method is valid and straightforward to calculate workspace.     

A new method of stress calculation in elastic kinetics problems

The conventional difference scheme described by Courant et al. [2] in 1928 is only a finite element method with a special integral approximation. A new method of calculating stress is presented in this paper, according to which the stresses acting on some small regions just satisfy the conservative difference equations for the kinetic equation. The results calculated for an elastic plane problem show that the error of stress obtained by this method is less than that yielded by the finite element method.