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在研究矩独立基本变量对响应分布影响的重要性测度的基础上,定义了基本变量对失效概率 的重要性测度. 基本变量对失效概率的重要性测度可以直接全面地给出基本变量对结构安全 影响的重要程度,因而该重要性测度将更具有工程指导作用. 文中分析了所定义基本变量对 失效概率影响重要性测度的基本性质,并基于鞍点线抽样在求解可靠度时不受随机变量分布 形式的限制及其效率和精度较高的优点,提出了求解该重要性测度的鞍点线抽样方法.     

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针对回转窑运行轴线变化所引起筒体发生弯曲振动, 推导了托轮系统各向异性等效刚度计算方程，发展了传递矩阵法来建立回转窑的动力 学模型，并进行实例求解分析，从理论上阐明了常用的轴线检测方法存在动态误差的本质缺 陷，为计算筒体动应力和轴线检测动态误差提供了基础方程.     

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从力平衡的角度,分析了抗滑桩的抗滑阻力与滑体的下滑力之间的依存关系以及传递过程. 利用弹性力学理论,推导出桩后土体应力场的分布函数. 通过绘制应力等值线图, 发现抗滑桩与土体之间产生土拱现象的机制是滑体内的应力状态由不平衡逐渐到 达平衡的结果,属于应力拱的表现形式.     

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简单回顾了被动行走的发展,建立了无量纲形式的平面直腿圆弧足被动行走动力学 模型,详细介绍了被动行走模型仿真的步骤. 并且采用胞胞映射计算得到该圆弧足模型的吸 引盆,发现该模型的吸引盆大于以前研究者研究的点状足模型的吸引盆. 这表明在初始状态 变量偏离不动点很大时,模型仿真仍可收敛到稳定的步态,即该模型具有较高的鲁棒性.     

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以``流体力学实验助手'课件为例，介绍了数据输入与处理课件在流体 力学实验教学中的应用. 该课件作为流体力学实验课程的辅助教学工具，用于学生在实验结 束后当场输入和保存实验数据,教师对学生实验报告的批阅和讲评，以及学生对发回实验报告 的检查和核对. 该课件的使用，节省了教师批阅和讲评学生实验报告所费时间和精力，并为 学生核查实验报告计算或作图是否正确提供了方便.     

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一个家庭关心下一代,这个家庭就兴盛;一个农场精心培育种子,这个农场就丰收.一个学科重视普及,这个学科就发展. 1979年3月,沐浴改革开放的春风,在<力学学报>复刊一周年之际,根据中国力学学会的规划, <力学与实践>创刊,宗旨是面向科研和工程一线的力学工作者及院校师生,传播和报道与力学相关的前沿领域、工程应用、教学经验和科学知识.一句话,就是普及力学的知识,播撒力学的种子.     

基于弯矩图计算超静定轴力的新方法

某些超静定结构,当弯矩图确立后,应用静力平衡条件无法绘出轴力图.分析该类结构的基本特征和受力特点,利用某些刚架在结点集中力作用下无弯矩、只有轴力的特点和力法的思想,提出解算已知弯矩图轴力超静定结构的计算方法.算例表明该方法简化了力法的计算过程,将其应用于教学,有利于学生对力法的深入理解.     

A new method for measurement of finger-phalangeal force

Finger-phalangeal forces during maximal isometric cylinder grasping have been measured by using pressure-sensitive sheets in order to intensify the finger pressure, ball mats have been used. An image-analysis system has been used to determine the force exerted by the finger phalanges from the density of stains on the pressure-sensitive film. The variation of the finger forces with different cylinder sizes has been investigated, and the locations of the phalangeal force centers have also been obtained. The present method is useful for the analysis of finger-pulp contact with an object, and also for optimizing handle-shape design.     

超静定桁架变形协调方程 的新方法

在三角形桁架变形协调的基础上，提出了建立超静定桁架的变形协调方程的新方法，此法简便易行，更利于数值计算。     

The Saint-Venant problem of plane bar under an axial force

I.PrefaceAsweknow,theSaint-Venanttheoryisawell-knownanduniversallyacceptedtheory.Butasoneofthegeneraltheoriesofelasticmechanics,itisnotprovedperfectely,althoughitistestedbyexperiments.Infact,onlyforthesimplestproblemofelasticity,itisnoteasytofindanalytics…     

A new method for measuring impulsive force at contact parts

A simple method has been devised for measuring the impulsive force generated at a contact part. Special sensing plates are used to produce an effect equivalent to the embedment of small strain gages in a solid. This method is effective for measuring the impulsive force directly and sensitively, it is almost entirely free from the disturbance caused by interference with reflected waves. It is even effective for the case in which an elastic-plastic deformation may occur at the contact part and the contact area may vary with time.     

Adaptive force density method for form-finding problem of tensegrity structures

A numerical method is presented for form-finding of tensegrity structures. Eigenvalue analysis and spectral decomposition are carried out iteratively to find the feasible set of force densities that satisfies the requirement on rank deficiency of the equilibrium matrix with respect to the nodal coordinates. The equilibrium matrix is shown to correspond to the geometrical stiffness matrix in the conventional finite element formulation. A unique and non-degenerate configuration of the structure can then be obtained by specifying an independent set of nodal coordinates. A simple explanation is given for the required rank deficiency of the equilibrium matrix that leads to a non-degenerate structure. Several numerical examples are presented to illustrate the robustness as well as the strong ability of searching new configurations of the proposed method.     

A new method of computation of wave fields using Gaussian beams

A new method of computation of wave fields of different physical nature in the high-frequency approximation is proposed. The method is based on summation of Gaussian beams. It enables us to compute the wave fields on arbitrary caustics without introducing any special functions. In the paper the three-dimensional point source problem for the Helmholtz equation is considered and all necessary formulas of the method are presented. The computation algorithm is discussed in detail on the basis of these formulas.     

一种有限元并行计算前处理方法

本文研究一种有限元并行计算前处理方法,只需将各子结构的超单元信息发送给各处理机,就可并行自动剖分各子结构和并行优化各子结构单元编号,以达到极小最大波宽和波宽的均主根,算例表明,该方法可大大减少有限元并行计算前处理时间。     

A multigrid pseudospectral method for steady flow computation

In this work two‐dimensional steady flow problems are cast into a fixed‐point formulation, Q = F(Q). The non‐linear operator, F, is an approximate pseudospectral solver to the Navier–Stokes equations. To search the solution we employ Picard iteration together with a one‐dimensional error minimization and a random perturbation in case of getting stuck. A monotone convergence is brought out, and is greatly improved by using a multigrid strategy. The efficacy of this approach is demonstrated by computing flow between eccentric rotating cylinders, and the regularized lid‐driven cavity flow with Reynolds number up to 1000. Copyright © 2003 John Wiley & Sons, Ltd.