大型公共建筑风险评估框架研究

大型公共建筑是开放复杂系统,其风险由可靠性风险、安全性风险和可持续发展性风险构成.大型公共建筑的风险评估、需要从系统的角度,针对3类风险的不同特性,采用定性与定量结合的方法,进行系统的风险评估.针对可靠性风险侧重系统的可靠程度评估,安全性风险侧重风险源和系统脆弱性评估,可持续发展性风险侧重关联风险事件评估.大型公共建筑...     

北京正负电子对撞机次级束质子单粒子翻转计算和试验研究

北京正负电子对撞机(BEPC)电子直线加速器试验束打靶产生的次级束中包含质子,其中能量约为50MeV~100MeV的质子占有很大比例,这弥补了国内高能质子源的空白。本工作计算得到次级束中的质子能谱,建立质子单粒子翻转截面计算方法,在北京正负电子对撞机次级束质子辐射环境中,计算静态随机存取存储器的质子单粒子翻转截面,设计了SRAM质子单粒子翻转截面测试试验,发现SRAM单粒子翻转和注量有良好的线性,这是SRAM发生单粒子翻转的证据。统计得到不同特征尺寸下SRAM单粒子翻转截面,试验数据与计算结果相符,计算和试验结果表明随着器件特征尺寸的减小器件位单粒子翻转截面减小,但器件容量的增大,翻转截面依然增大,BEPC次级束中的质子束可以开展中高能质子单粒子效应测试。     

基于进化蒙特卡洛方法的特征选择在机械故障诊断中的应用

特征选择可以从原始特征集中去除冗余特征,选择出优化特征子集,提高机械故障诊断精度和诊断效率。将进化蒙特卡洛方法引入机械故障诊断的特征选择。应用支持向量机(SVM)作为故障决策器,采用Wrapper式特征子集评价标准,并采用进化蒙特卡洛算法搜索最优特征子集。运用滚动轴承故障振动信号数据对提出的方法进行验证,实验结果表明该方法是有效的。     

SRAM型FPGA单粒子翻转测试及加固技术研究

SRAM型FPGA空间应用日益增多,只有针对其特点设计相应的单粒子试验的测试程序才能系统、准确地获取该类芯片的单粒子翻转特性,为抗辐射加固设计提供依据.阐述了单粒子翻转的静态和动态的测试方法.静态测试包括硬件设计和配置位回读程序的设计;动态测试主要针对CLB(配置逻辑单元)和BRAM(块存储器)两部分进行了相应的软件测...     

On the need for the use of error‐controlled finite element analyses in structural shape optimization processes

This work analyzes the influence of the discretization error associated with the finite element (FE) analyses of each design configuration proposed by the structural shape optimization algorithms over the behavior of the algorithm. The paper clearly shows that if FE analyses are not accurate enough, the final solution provided by the optimization algorithm will neither be optimal nor satisfy the constraints. The need for the use of adaptive FE analysis techniques in shape optimum design will be shown. The paper proposes the combination of two strategies to reduce the computational cost related to the use of mesh adaptivity in evolutionary optimization algorithms: (a) the use of an algorithm for the mesh generation by projection of the discretization error, which reduces the computational cost associated with the adaptive FE analysis of each geometrical configuration and (b) the successive increase of the required accuracy of the FE analyses in order to obtain a considerable reduction of the computational cost in the early stages of the optimization process. Copyright © 2011 John Wiley & Sons, Ltd.     

Crack Tip Opening Angle Measurement Methods and Crack Tunnelling in 2024‐T351 Aluminium Alloy

Abstract: The crack tip opening angle (CTOA) fracture criterion is one of the most promising fracture criterion used to characterise the stable tearing process in metallic materials. Traditional methods used for the experimental characterisation of the CTOA involve accurate identification of the crack tip at each tearing event. Recently alternative methods have been proposed that reduce the necessity of accurately defining the current crack and rely more on the shape of the crack flanks to define the CTOA. In addition, these methods define an ‘apparent crack tip’, which may be different from the actual surface crack tip and may provide insight into the amount of crack‐front tunnelling that is occurring. In the current research, compact tension specimens fabricated from 6.35 mm thick 2024‐T351 aluminium alloy plate were evaluated to investigate different CTOA measurement methods and their potential for estimating crack‐front tunnelling. In addition to characterizing the CTOA, fatigue marker bands were employed to map the evolution of crack‐front tunnelling. The experimental critical CTOA values obtained from the alternative methods were noticeably lower than that obtained from the traditional approach and showed noticeably more scatter. When compared to the experimentally obtained marker bands, the alternative methods indicated limited potential for predicting crack‐front tunnelling.     

基于量子进化算法的高校排课方法设计

排课既是高校教学管理中一项重要而复杂的工作,又是一个多目标约束组合优化问题,为此使用量子进化算法来求解高校排课问题。首先研究了量子进化算法的关键技术,然后根据量子进化算法求解优化问题的思路设计了高校排课算法。通过实验表明,本文方法能够根据开课任务自动完成排课过程,排课的成功率和效率都比较好。     

Signalling chains with probe and adjust learning

Many models explain the evolution of signalling in repeated stage games on social networks, differently in this study each signalling game evolves a communication strategy to transmit information across the network. Specifically, I formalise signalling chain games as a generalisation of Lewis' signalling games, where a number of players are placed on a chain network and play a signalling game in which they have to propagate information across the network. I show that probe and adjust learning allows the system to develop communication conventions, but it may temporarily perturb the system out of conventions. Through simulations, I evaluate how long the system takes to evolve a signalling convention and the amount of time it stays in it. This discussion presents a mechanism in which simple players can evolve signalling across a social network without necessarily understanding the entire system.     

单粒子翻转敏感区定位的脉冲激光试验研究

利用脉冲激光单粒子翻转敏感区定位成像系统,对静态随机存储器件IDT71256开展了单粒子翻转敏感区定位的试验研究。为避开器件正面金属层对激光的阻挡,试验采用背面辐照方式进行测试。试验结果表明,存储单元中存储数据类型对器件单粒子翻转的敏感性有较大影响,由测得的单粒子翻转敏感区分布图经处理得到单粒子翻转截面,结果与重离子试验测得的翻转截面数据一致。     

加速器单粒子效应样品温度测控系统研制及实验应用

为满足国内半导体器件单粒子效应(SEE)截面与温度的关系研究需求,本文基于北京HI-13串列加速器SEE辐照实验终端研制了样品温度测控系统,实现了90~450K范围内实验样品温度的测量和控制,系统控制精度好于±1K。为验证系统可靠性,使用该系统研究了SRAM单粒子翻转(SEU)截面随温度的变化关系,在215~353 K范围内测量了SRAM翻转截面随温度的变化曲线。结果表明,SRAM SEU截面随温度的升高而增加,与理论预期结果一致。