有限变形理论能量释放率增率形式

基于有限变形理论中的能量原理和变分原理,考虑以有裂纹的瞬时位形为参考,建立增量变形引起的裂纹扩展方程能够更真实的描述裂纹尖端的扩展机制,在含有裂纹物体的瞬时变形的基础上,推导了裂纹体的能量释放率和增率的形式,提出了裂纹扩展判据.该判据反映了单位时间内裂纹扩展单位面积可以提供的能量与单位时间内裂纹扩展单位面积所需要的能量...     

Multi-objective Topology Optimization of Thermo-mechanical Compliant Mechanisms

The material characteristics of a structure will change with temperature variation,and will induce stress within the structure.Currently,the optimal design for the topology of compliant mechanisms is mainly performed in single physical field.However,when compliant mechanisms work in high temperature environments,their displacement outputs are generated not only by mechanical load,but also by the temperature variation which may become the prominent factor.Therefore,the influence of temperature must be considered in the design.In this paper,a novel optimization method for multi-objective topology of thermo-mechanical compliant mechanisms is presented.First,the thermal field is analyzed with finite-element method,where the thermal strain is taken into account in the constitutive relation,and the equivalent nodal thermal load is derived with the principle of virtual work.Then the thermal load is converted into physical loads in elastic field,and the control equation of the thermo-mechanical compliant mechanism is obtained.Second,the mathematical model of the multi-objective topology optimization is built by incorporating both the flexibility and stiffness.Meanwhile,the coupling sensitivity function and the sensitivity analysis equations of thermal steady-state response are derived.Finally,optimality criteria algorithm is employed to obtain numerical solution of the multi-objective topology optimization.Numerical examples show that the compliant mechanisms have better performance and are more applicable if the temperature effect is taken into account in the design process.The presented modeling and analysis methods provide a new idea and an effective approach to topology optimization of compliant mechanisms in electrothermic coupling field and multiphysics fields.     

PARALLEL LATTICE BGK SIMULATION OF NATURAL CONVECTION IN A CAVITY

1.INTRODUCTIONOver the last two decades,the LBM has at-tracted much attention as a novel alternative nu-merical method different from traditional CFDmethod for si mulating complex fluid flows[1-3].Ithas already found extensive applications in si mula-ting the physical phenomena of various complexi-ties ranging fromflows in porous media[4],magne-to hydrodynamics[5],multidi mensional transientflow[6]and i mmiscible fluids[7]to turbulence[8,9].Compared with conventional numerical methods,t…     

BCL-3: A High Performance Basic Communication Protocol for Commodity Superserver DAWNING-3000

1 IntroductionC1usters have been popu1ar platforms fOr high performance computing in receot years. They arewidely used in scientific and engineering computing business computing, and Internet informationservices. Communication perfOrmance is one of the most critical factors determining the perfOrmanceof a whole cluster system. So how to improve the performance of communication is a hot researchtopic in cluster computing. Meanwhile, bui1ding a cluster with commodity SMPs (CLUMPS) isbecorn…     

具有区间参数的VRP及其改进的C-W节约算法

在传统的车辆路径问题的基础上,针对配送中心到客户以及客户到客户之间的费用为区间参数时的车辆路径问题,建立了相应的数学模型.用可能度的区间数排序方法对费用区间参数进行排序并应用到C-W(clark-wright)节约算法中,提出了改进的C-W节约算法.通过算例验证了该算法的有效性和可行性.     

安全逻辑器件与CMOS B／T逻辑电路及其噪声容限

本文从容错计算技术的使用效果出发,将其分为故障诊断、资源冗余和故障安全三类技术。在分析传统故障安全技术的基础上,建立了一个统一的安全逻辑系统概念模型,并以此对该种系统进行了分类。作为一类扩展故障安全逻辑器件,文章重点介绍了三中取二值CMOS 逻辑电路,并参照CMOS 二值集成电路参量体系,结合实际测量结果提出了CMOS 三中取二值逻辑器件噪声容限的定义及其解法,从而为进一步完善该类新型器件的参量体系奠定了基础,同时还有利于其推广应用。     

时态关系代数与元组演算的等价性

建立了一个时态关系代数和时态元组演算并证明了他们间的等价性。     

大型计算机网络信息系统CNIS的研制

本文介绍一个以DECnet-VAX计算机为主干的远程网络。开发研制内容包括NECACOS和其他异种机入网、文电处理、点对点终端实时会话、文件传送、NECPC－9801微机终端仿真等功能的综合信息系统。讨论了它的主要功能和实现技术。     

面向对象的概念化个体分类结构的设计和实现

概念化个体的分类层次结构是智能信息处理系统中模型化问题域的一种有效方法。中探讨如何把概念化个体的分类层次结构与面向对象的程序设计风格和多种知识表示方法相结合，给出在面向对象环境下概念化个体的分类层次结构的设计及其实现算法。