HALT技术在变频器中的应用初探

HALT技术可在产品设计阶段快速消除设计缺陷,缩短研发时间和成本,迅速提高产品的质量和固有可靠性。本文从HALT试验的背景出发,介绍了HALT试验的基本原理和意义。在对HALT箱各方面性能验证的基础上,针对我司11kW变频器,详细讲述了HALT试验的具体操作过程。     

基于Abaqus的汽车发动机罩应力响应分析

利用Abaqus建立某汽车发动机罩的详细模型,对发动机罩的关闭过程进行显式动力学仿真,研究发动机罩大力关闭时的应力响应.通过试验测试发动机罩局部的应变,并与计算结果对比分析.结果表明该方法可准确预测发动机罩关闭时的瞬态应力响应,指导发动机罩的强度耐久设计.     

擦窗机悬挂轨道三维结构有限元分析

为探究某擦窗机悬挂结构的合理性,在AIP中创建其悬挂轨道的三维参数化特征模型,并根据轨道的结构、材料和特定工况受力等边界条件,建立悬挂系统的有限元模型,模拟计算2种有代表性的偏栽荷工况受力情况,得到悬挂轨道的三维应力分布、结构变形和安全因数．根据工程设计要求和初步分析结果,在保持边界条件和载荷条件不变的情况下,快速更新轨道结构参数,并通过比较分析确定塔楼悬挂轨道的最佳断面参数．该轨道及其固定间距、滑车滚轮和导向轮等构件均满足设计安全要求．     

冷却器在瞬态工况下的温度场与热应力分析

针对冷却器在发电厂寿命期内频繁承受热冲击作用而导致设备出现疲劳破坏问题,用ANSYS建立设备管程结构温度场和应力场分析模型,计算瞬变热冲击工况下结构的热应力,并按ASME标准对设备的疲劳强度进行评定.数值仿真结果可明确冷却器裂纹产生的主要原因和部位,为结构的安全性改进提供参考.     

建基岩体开挖前后的声波曲线特性及其成因分析

自然斜坡在形成演化过程中,受区域构造、河谷下切、地壳隆升以及外部营力(如风化卸荷)作用,加之岩体物理力学特性等多种地质环境因素影响,可在岸坡浅表层(由表及里)形成应力释放区、应力调整区和原始地应力稳定区;但在岸坡(建基)岩体人工开挖过程中,由于爆破扰动及岩体瞬间卸荷等影响,以上应力分区将重新波动调整。声波VP作为评价岩体质量优劣的一个重要指标,因具备简便、快速、准确、可靠等特点得到了广泛应用与发展。现就此以前期勘探平硐声波测试及开挖坝面岩体质量单孔声波检测结果为基础,讨论建基岩体开挖前后波速曲线的形态特征以及应力分区分布范围,并分析导致曲线形态的地质原因,以期为坝基开挖及后续声波监测工作等提供一定的科学依据。     

A parametric periodic Lyapunov equation with application in semi-global stabilization of discrete-time periodic systems subject to actuator saturation

This paper is concerned with semi-global stabilization of discrete-time linear periodic systems subject to actuator saturation. Provided that the open loop characteristic multipliers are within the closed unit circle, a low gain feedback design approach is proposed to solve the problem by state feedback. Our approach is based on the solution to a parametric discrete-time periodic Lyapunov equation. The proposed approaches not only generalize the corresponding results for time-invariant systems to periodic systems, but also reveal some important intrinsic properties of this class of periodic matrix equations. A numerical example is worked out to illustrate the effectiveness of the proposed approaches.     

压缩感知中的信号重构方法分析

压缩感知理论(CS)因高采样速率和巨大的存储空间被广泛应用于认知无线电中.重构算法是压缩感知理论的核心之一,也是目前的研究热点.介绍了压缩感知理论的基本模型和重构算法,在基本的梯度算法(GP)基础上做了改进,提出了巴兹莱一伯文(PBB)算法,并对两种重构算法进行了仿真.仿真结果表明,PBB算法能更好地重构信号.     

A new approach for the solution of singular optima in truss topology optimization with stress and local buckling constraints

The present paper investigates problems of truss topology optimization under local buckling constraints. A new approach for the solution of singular problems caused by stress and local buckling constraints is proposed. At first, a second order smooth-extended technique is used to make the disjoint feasible domains connect, then the so-called ε-relaxed method is applied to eliminate the singular optima from problem formulation. By means of this approach, the singular optimum of the original problem caused by stress and local buckling constraints can be searched approximately by employing the algorithms developed for sizing optimization problems with high accuracy. Therefore, the numerical problem resulting from stress and local buckling constraints can be solved in an elegant way. The applications of the proposed approach and its effectiveness are illustrated with several numerical examples. Received May 2, 2000     

An enhanced error estimator on the constitutive relation for plasticity problems

This paper presents an extension to plasticity problems of a new error estimator on the constitutive relation which was introduced by P. Ladevèze in a recent paper. Numerical experiments show that this enhanced error estimator can lead to a significant improvement in the effectivity indexes in the case of anisotropic meshes, or when perfect plasticity is approached.     

在Windows环境下开发应力测试系统控制软件的研究

讨论了在Ｗｉｎｄｏｗｓ环境下用 Ｄｅｌｐｈｉ３开发半导体应力自动测量系统控制软件的方法和关键细节。介绍硬件与软件调试中要注意的问题。对 Ｗｉｎｄｏｗｓ环境下开发控制硬件工作的软件进行了探讨。