Case‐based reasoning and improved adaptive search for project scheduling

Most scheduling problems are notoriously intractable, so the majority of algorithms for them are heuristic in nature. Priority rule‐based methods still constitute the most important class of these heuristics. Of these, in turn, parametrized biased random sampling methods have attracted particular interest, due to the fact that they outperform all other priority rule‐based methods known. Yet, even the “best” such algorithms are unable to relate to the full range of instances of a problem: Usually there will exist instances on which other algorithms do better. We maintain that asking for the one best algorithm for a problem may be asking too much. The recently proposed concept of control schemes, which refers to algorithmic schemes allowing to steer parametrized algorithms, opens up ways to refine existing algorithms in this regard and improve their effectiveness considerably. We extend this approach by integrating heuristics and case‐based reasoning (CBR), an approach that has been successfully used in artificial intelligence applications. Using the resource‐constrained project scheduling problem as a vehicle, we describe how to devise such a CBR system, systematically analyzing the effect of several criteria on algorithmic performance. Extensive computational results validate the efficacy of our approach and reveal a performance similar or close to state‐of‐the‐art heuristics. In addition, the analysis undertaken provides new insight into the behaviour of a wide class of scheduling heuristics. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 201–222, 2000     

65纳米工艺双层三维静态存储器的软错误分析与评估

首先搭建了3D SRAM软错误分析平台,可以快速、自动分析多层die堆叠结构3D SRAM的软错误特性。此平台集成了多种层次模拟软件Geant4、TCAD、Nanosim,数据记录处理软件ROOT,版图处理软件Calibre,以及用于任务链接和结果分析的Perl和shell脚本。利用该平台,对以字线划分设计的3D SRAM和同等规模的2D SRAM分别进行软错误分析,并对分析结果进行了对比。对比分析表明2D 和3D SRAM的翻转截面几乎相同,但3D SRAM单个字中发生的软错误要比2D SRAM更严重,导致难以使用ECC技术对其进行加固。静态模式下2D SRAM和3D SRAM敏感节点均分布于存储阵列中,表明静态模式下逻辑电路不会引发软错误。     

基于改进快速扩展随机树的机械臂路径规划

针对机械臂路径规划问题,提出一种基于改进RRT算法的路径规划方法。改进RRT结合了目标偏置策略和贪婪生长策略的优点,在随机采样时,以一定概率使采样点偏置为目标节点,降低随机采样的盲目性,在目标节点方向上采用贪婪式扩展策略,增加随机树局部方向上的生长速度。RRT法规划路径结果并非最优,提出改进GPP法删除多余路径节点,优化机械臂运动路径。通过与Biased-RRT和Greedy-RRT数值仿真结果对比,证明了改进RRT在计算时间、迭代次数、扩展节点数上均优于以上方法。在机械臂两种典型工作环境中的仿真结果表明,使用该方法可以较好解决排爆机械臂避障路径规划问题。     

软件无失效测试数据的统计分析

软件可靠性估计是软件可靠性研究的重要问题之一,文中对分布式软件系统可靠性的评估方法进行了研究,给出了软件系统可靠度的最优置信下限.最后以某大型软件的评估为例,说明该方法的应用.     

二阶矩模糊随机过程的均方极限

给出了二阶矩模糊随机过程均方极限的两种定义,证明了这两种定义的等价性,并讨论了二阶矩模糊随机过程均方极限的性质。     

随机载荷下疲劳寿命预估计算方法研究

分析了一种用于随机载荷下零构件疲劳寿命预估的有效计算方法 .引入材料所吸收的弹性应变能和塑性应变能等参量 ,在等能量损伤法则下推算出稳态条件下随机载荷的等价常幅应力 ,适用于结构设计阶段和改进阶段或应力响应时间历程无法实测的情况 .     

A componentwise index of service measurement in multi‐component systems

In this paper we present a componentwise delay measure for estimating and improving the expected delays experienced by customers in a multi‐component inventory/assembly system. We show that this measure is easily computed. Further, in an environment where the performance of each of the item delays could be improved with investment, we present a solution that aims to minimize this measure and, in effect, minimizes the average waiting time experienced by customers. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 50: 2003     

Network reliability assessment in a random environment

In this paper we consider networks that consist of components operating under a randomly changing common environment. Our work is motivated by power system networks that are subject to fluctuating weather conditions over time that affect the performance of the network. We develop a general setup for any network that is subject to such environment and present results for network reliability assessment under two repair scenarios. We also present Bayesian analysis of network failure data and illustrate how reliability predictions can be obtained for the network. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 574–591, 2003     

区域目标搜索中基于改进RRT的UAV实时航迹规划

在线自主航迹规划是无人机(Unmanned Aerial Vehicles,UAV)执行区域目标搜索任务的有效保证.针对UAV区域搜索中航迹规划的实时性要求,提出了一种固定搜索模式和动态搜索模式相结合的UAV自主航迹规划框架.在快速扩展随机树(RRT)方法的基础上,通过改进随机扩展树的节点选择和引入启发式信息,提出了基于改进RRT的UAV实时搜索航迹规划算法,该算法能够有效降低在线航迹规划的时间代价和扩展节点数.仿真实验结果验证了本文方法的有效性.     

指控系统随机扫描方式CRT视频显示系统改装设计

针对 CRT显示器的缺点提出了对显示部件进行改进设计方案,采用当前在军事领域大量使用的LCD平板显示器和计算机控制技术,利用程控译码器和视频显示器的接口信号,实现显示目的并提高显示效果.在改进方案中采用了A/D转换技术、中断等技术,利用控制信号产生中断进行模拟信号的采集和数字信号的提取,译码后在LCD显示器上复现出来.改进后的显示器除能完成所有CRT显示器的功能外还具有自校准功能,且可以显示中文参数表页,使操作更加简便.