A Hierarchical structure of key performance indicators for operation management and continuous improvement in production systems

Key performance indicators (KPIs) are critical for manufacturing operation management and continuous improvement (CI). In modern manufacturing systems, KPIs are defined as a set of metrics to reflect operation performance, such as efficiency, throughput, availability, from productivity, quality and maintenance perspectives. Through continuous monitoring and measurement of KPIs, meaningful quantification and identification of different aspects of operation activities can be obtained, which enable and direct CI efforts. A set of 34 KPIs has been introduced in ISO 22400. However, the KPIs in a manufacturing system are not independent, and they may have intrinsic mutual relationships. The goal of this paper is to introduce a multi-level structure for identification and analysis of KPIs and their intrinsic relationships in production systems. Specifically, through such a hierarchical structure, we define and layer KPIs into levels of basic KPIs, comprehensive KPIs and their supporting metrics, and use it to investigate the relationships and dependencies between KPIs. Such a study can provide a useful tool for manufacturing engineers and managers to measure and utilize KPIs for CI.     

基于消息中间件的短信息服务平台设计与实现

介绍消息中间件在短信息服务平台的设计与实现,系统以开源消息中间件Active MQ为核心平台,使用Java为编程语言,实现系统的高性能、分布式、松耦合性.     

基于时域积分方法分析PCB串扰问题

采用时域积分方程法及改进型节点分析法对PCB板间导线的串扰问题进行建模.时域积分方程法以等效原理为基础,在矩量法应用中加入时间因子的考虑,并采用RWG基函数将模型划分为多个三角面元,从而将导线间的影响以散射的角度来表达.另外采用改进节点分析法对电路边界不连续性进行求解,从而懈决了有限电导率导体和各向同性介质相结合情况下的串扰问题.最后在多层PCB传输线的算例中,计算给出了不同条件下输出电压和串扰电压波形的时域变化,从而对PCB板间信号完整性做出了分析.     

大电网未来态一体化模型构建和融合技术研究

随着中国智能电网规模与复杂性的不断增加,针对未来态电网模型的应用需求日益强烈,现阶段调度自动化系统对于未来态建模缺乏快速高效的建模手段,缺乏上下级调度系统间未来模型的协调融合机制。通过研究电网未来模型管理体系架构,在不影响实时系统安全稳定运行的前提下,通过数据分片技术、分布式文件数据库的应用,通过基于消息中间件数据交互技术和以厂站为粒度的未来模型融合方法,实现模型未来版本维护环境的快速构建,实现网省一体化的未来模型融合的高效管理,满足不同应用对未来图模多版本维护的需求并为应用计算提供了一整套的解决方案。     

JMS信息发布异构平台应用研究

有效结合JMS技术与XML技术,提出了基于JMS的信息发布平台的系统分析和设计,并给出了具体实现方法,构建了一个基于JMS的跨平台消息发布平台,应用效果良好,具有重要的实际应用价值。     

扎鲁特-青州UHVDC工程换流站阀厅辐射电磁干扰水平预测分析

文中以扎鲁特-青州±800 kV特高压直流工程为背景,对其换流站阀厅辐射电磁干扰水平进行了预测评估。提出了一种更为精确地计算辐射电磁干扰的方法,计算了换流站多种运行状况下阀厅的辐射电磁干扰强度。首先基于天线耦合原理,对时域仿真得到的多种运行状况下干扰电流进行修正,获得更为精确的干扰电流;然后以计算辐射电磁干扰的天线模型为基础,采用矩量法对多种运行状况下的换流站阀厅辐射电磁干扰强度进行了计算。本文为制定特高压直流输电工程换流站阀厅辐射电磁干扰的抑制措施提供了依据。     

多天线-散射体结构矩量法分析的自动网格划分方法

针对多天线-散射体(散射体可看作是由三角形面和四边形平面围成的几何体)结构,提出了一种基于矩量法的散射面自动网格划分方法。该方法通过三次网格划分得到符合矩量法分析要求的三角形面元、四边形面元。首先对散射体各表面按无天线连接并遵循面积条件进行递归二分,得到符合面积要求的面元,这就是第1次网格划分;接着分4种情况对连接有天线的有关面元进行再一次划分,得到线面结合点在中心的正方形面元以及若干三角形、四边形面元,这就是第2次网格划分;最后对狭长的面元进行第3次网格划分,得到质量较好的面元。多项工程应用表明,该网格划分方法稳定、可靠、速度快、适应性强。     

含有折线型缝隙金属平板散射分析

分析了有限大金属平板上包含折线形状缝隙时的散射场。缝隙和金属平板的散射分别采用矩量法和物理光学法得到。折线型缝隙由两种不同倾斜方向的直缝组成,然后叠加各段缝隙和金属板的散射场即可得到总场。     

无线设备互调干扰仿真分析

系统电磁兼容(EMC)设计中,无线设备间互调干扰是非常严重的一个问题.本文首先建立了无线设备间互调干扰量的分析模型,并采用矩量法结合微波网络的方法求出互调干扰模型中最重要的参数天线间耦合度,然后把发射及接收设备的给定数据代入干扰模型算出发射机和接收机间互调干扰的量级.经过仿真数据与实测数据的对比,证明该方法理论正确,计算精度较高,文章最后给出了仿真实例.     

General Methods for Synthesis of N‐Methyliminodiacetic Acid Boronates from Unstable ortho‐Phenolboronic Acids

A range of N‐methyliminodiacetic acid (MIDA) boronates of commercially available but unstable ortho‐phenolboronic acid derivatives can be readily prepared through simple condensation between the corresponding phenolboronic acids and MIDA in the presence of molecular sieves. The resulting MIDA boronates are bench‐top stable and display a remarkable stability even in DMSO solution at high temperature (>120 °C) compared with their parent boronic acids. Moreover, the utility of the resulting MIDA boronate was successfully demonstrated in a cross‐coupling reaction using the slow‐release protocol to afford the cross‐coupled product in much better yield compared with its parent boronic acid counterpart. In addition, an alternative, but more efficient, synthetic route for difficult‐to‐access ortho‐phenol MIDA boronates has been developed through the MIDA boronate formation of methoxymethyl (MOM) protected ortho‐phenolboronic acid, followed by deprotection of the MOM group with TMSCl under ambient conditions.