蜂群算法在装备维修任务调度中的应用

如何在最短的时间内将损坏的装备修复好,是装备维修决策的重要内容之一。鉴于蜂群算法在任务调度特别是动态随机任务调度中的优势,将蜂群算法引入装备维修任务调度研究。测试案例的仿真结果表明,蜂群算法对于动态随机任务调度具有较强的优势。     

自乳化型水性醋酸纤维素乳液的制备与性能研究

以二羟甲基丙酸(DMPA)为亲水扩链剂,以醋酸纤维素(CA)、异佛尔酮二异氰酸酯(IPDI)和三乙胺(TEA)等为主要原料,成功制备出一种自乳化型WCA(水性醋酸纤维素)乳液,并采用正交试验法优选出制备WCA乳液的最佳工艺条件。研究结果表明:当n(DMPA)∶n(IPDI)=0.40∶1、n(CA)∶n(IPDI)=3∶1、中和度为0.9、第一(第二)阶段反应温度和反应时间分别为50℃(75℃)和60 min(90 min)时,该环保型WCA乳液的耐水性、柔韧性和粘接强度(2.9 N/mm)俱佳,并且其制备工艺简单、可室温粘接以及成本较低,具有良好的应用前景。     

快速蒙特卡罗方法实现电子线路容差分析

介绍了电子线路容差分析的基本原理,提出了基于MATLAB电子线路最坏情况分析、蒙特卡罗分析和快速蒙特卡罗分析方法的实现方法。通过对具体电子线路容差分析结果的对比,得出了采用快速蒙特卡罗分析方法比其它两种方法更有效。     

ASTM A216 WCA钢奥氏体化过程中的组织演变

采用膨胀试验和淬火试验研究了ASTM A216 WCA钢奥氏体化过程中的组织演变,分析了不同加热速率对奥氏体化过程的影响,并通过金相分析方法研究了加热过程中各相相分数的变化。结果表明,随着加热速率的增大,奥氏体化转变开始温度和结束温度均升高,初始奥氏体晶粒尺寸减小;同时可以看出,奥氏体化过程中珠光体向奥氏体的转变速度比铁素体向奥氏体的转变速度快。     

航天器用二次电源优化设计与最坏情况分析

针对航天器用二次电源电路设计的特殊要求,采用反激拓扑主电路,并设计了输入欠压保护电路、输入/输出过压保护电路、输入限流保护电路。考虑高低温对电路三极管β值的影响,通过参数扫描分析对输入欠压保护电路元器件进行了参数优化。考虑元器件初始偏差、温度老化等对电路元器件的影响,对DC/DC电路进行了最坏情况分析,采用saber软件进行了仿真,仿真结果表明:设计的二次电源电路输出电压更加稳定且满足(13.6±0.2)V的波纹要求。     

Influence of gold pick up on the hardness of copper free air ball

The effect of substrate material pick up by the Cu wire tail on the hardness of the subsequently formed free air ball (FAB) is investigated with scanning electron microscopy (SEM) and micro-hardness test. The Cu wire bonds are made on Au metallization. Wire residue is not found on the imprint the tail bond leaves on the metallization, but fracture of the substrate metallization is evident. SEM images of the Cu wire tail end clearly show Au residue (pick up). The amount of Au pick up is estimated higher than 0.03% of the volume of a subsequently formed 50 μm diameter FAB, exceeding typical impurity and dopant concentrations (0.01%). Lowering the impact force process parameter is found to strongly increase the amount of substrate material pick up. Cu free air balls (50 μm in diameter) formed with an estimated Au pick up volume of 50 μm³ are found to be between 1.2 HV and 4.3 HV softer than those without pick up. However, the hardness varies significantly more than that of FABs without pick up.     

一种基于簇的分布式路由协议

目前的分簇算法一般基于移动节点初始状态静止的假设,且部分算法在节点移动或节点退出时会导致全局簇结构的重建。针对上述问题,提出一种基于权值的分布式分簇算法,利用该算法改进CBRP协议,提出DRP协议。运用NS-2模拟仿真工具对CBRP与DRP的性能进行分析,结果显示,DRP具有较高的吞吐率和较低的网络开销。     

Ad Hoc网络自适应安全加权分簇算法

为解决Ad Hoc网络分簇过程中恶意节点被选为簇首带来的安全隐患,保障Ad Hoc网络的正确分簇和稳定运行,提出基于节点相关度、相对移动性、剩余能量值、安全评估度量值多方面因素的自适应安全加权分簇算法。安全评估度量参数由外部入侵检测系统和内部节点信任度共同计算得到,确保安全因素在分簇过程中的准确性;基于该算法给出相应分簇管理过程。仿真结果表明,该算法能够改善分簇性能,提高Ad Hoc网络的安全性。     

ASTM A216 WCA铸钢凝固及冷却过程相变的CA模拟

结合Thermo-Calc和Dictra软件考虑了多组元条件下的凝固和溶质扩散过程,建立了元胞自动机(CA)模型,对ASTM A216 WCA铸钢凝固及后续冷却过程的相变进行了模拟.设计了阶梯形试件进行浇注与测温实验,并用OM和SEM观察了铸态试件不同部位的微观组织,测定了先共析α铁素体的含量及其晶粒尺寸、珠光体的层片间距,并将数值模拟结果和实验结果进行了对比,分析了冷却条件对铸态微观组织的影响.结果表明,模拟结果与实验结果符合良好,随冷却速率的增大,先共析α铁素体的含量增加,同时,先共析α铁素体的平均晶粒尺寸和珠光体的平均层片间距减小.     

Targeting water utilities for the threshold problem without waste discharge

Increasing water scarcity and stringent environmental regulation have necessitated effective water conservation policies. Pinch analysis has been proved as one of the powerful tools to locate targets of waste water minimization. Two earlier water pinch targeting methods known as Water Cascade Analysis and Material Recovery Pinch Diagram have focused on the “threshold problems”. However, these methodologies have not systematically analyzed the introduction of external utility. In this work, three scenarios are proposed for this reason. The “Infeasible Threshold Problem” is addressed prior to employing external utility through the proposed scenarios. By systematically analyzing this specific problem, it is revealed that existing Water Cascade Analysis method cannot locate correct infeasible targets. Some adjustments are proposed to deal with this drawback. Moreover, to illustrate the applicability of proposed scenarios, Water Cascade Analysis and Material Recovery Pinch Diagram approaches are utilized for addressing a literature problem as a case study. It is shown that harvesting the impure fresh water source with a higher quality, in the “threshold problem with zero discharge”, leads to more pure fresh water saving.