基于最优权重与雷达图的变压器状态评估

实现更加贴近电力变压器实际运行状态的评估,对于电网合理、经济、科学安排检修具有重要意义。针对主观、客观权重单一评估或者简单将二者拟合造成整体评估片面性的问题,提出了基于最小方差理论的最优组合赋权方法,使得权重得到更加合理的分配。将雷达图法的特征量计算方法应用到变压器评估中,使得评估结果更加直观、简洁,也避免数据信息在归一化过程中的遗漏。运用该方法对实际变压器数据进行了分析,验证了方法的可行性和合理性。     

采空区自燃理论模型的无因次分析与应用

预测预报是采空区自燃防治的主要措施,但采空区自然发火的影响因素众多,并且各因素之间往往相互关联,这给采空区自燃的预测带来了很大困难。选取回采工作面长度作为物理模型的基准尺寸,同时选取了基准速度、基准氧气浓度和基准温度等参考值,依据这些基准参考值定义了无因次压力、无因次氧扩散系数、傅里叶准数等无因次准则。在这些无因次准则的基础上依据量纲一致原理将采空区自燃模型转换成了无因次模型。然后逐个分析模型中的无因次准则对采空区自燃的影响,将影响自燃的主要无因次准则为组合成耗氧和放热2个无因次准则。进一步分析这2个准则的取值范围,并在它们的取值范围内取2个自燃准则的不同组合进行自燃的模拟,得到采空区的最高无因次温度,并绘制成采空区自燃判别图用以对采空区自燃进行判别。     

基于能见度图的元胞疏散最短路径模型研究

近年来发生的火灾多在人员密集场所,当突发事件发生时,人员疏散往往特别困难,因此,规划行人在大型公众聚集建筑物中的疏散路径非常重要。基于能见度图建构的元胞疏散最短路径模型可直接用于实际的紧急疏散指示路径的规划,避免设置大量逃生指示装置致使工程成本过高及视觉不美观,并且也解决了有限制逃生指示装置数量当作限制条件的最大涵盖面积的求解复杂、空间大的问题。     

Developing a procurement path determination chart SEM-based approach

The choice of an appropriate procurement system is crucial to construction project success. Procurement selection is largely based on path determination charts, with at least eight key criteria needing to be weighted by decision-makers. Including certain criteria whilst ignoring client-borne transaction costs (TCs) resulting from environmental uncertainties simplifies this process. TCs are ‘unseen’ costs associated with pre- and post-contract work. The effects of uncertainties in the transaction environment and procurement systems on TCs are investigated, comparing the traditional and design-build procurement systems. A cross-sectional sample approach was deployed, involving survey questionnaire and results verification through ‘real-world’ cases. Data was sought from construction professionals in management, design and operation of construction projects. The research participants evaluate their time spent on procurement activities using a five-point Likert scale. Hypotheses of the relations between environmental uncertainties, procurement systems, and pre- and post-contract TCs are tested using a structural equation modelling (SEM) approach. The study found that TCs account for about 46.75% and 42.88% of the daily time spent by project managers in traditional and design-build procurement systems in New Zealand respectively. The study concludes that the TC concept is a useful framework for determining objective instead of subjective opinions for procurement decisions.     

两极控制图在注塑瓶盖壁厚控制中的应用

针对注塑瓶盖壁厚控制的特点,介绍了统计过程控制(SPC)中的均值-极差(x-R)控制图在塑料瓶盖壁厚控制中的局限性,将两极(L-s)控制图与均值-极差控制图进行了比较,阐述了两极控制图在塑料瓶盖壁厚控制中的优越性,论述了两极控制图的构造原理和控制限计算方法,提出了两极控制图在注塑瓶盖壁厚控制中的应用,并在对两极控制图分析的基础上,对注塑成型的过程能力进行分析和改善。     

A study of process monitoring based on inverse Gaussian distribution

The inverse Gaussian distribution has considerable applications in describing product life, employee service times, and so on. In this paper, the average run length (ARL) unbiased control charts, which monitor the shape and location parameters of the inverse Gaussian distribution respectively, are proposed when the in-control parameters are known. The effects of parameter estimation on the performance of the proposed control charts are also studied. An ARL-unbiased control chart for the shape parameter with the desired ${\mathit{ARL}}_0$, which takes the variability of the parameter estimate into account, is further developed. The performance of the proposed control charts is investigated in terms of the ARL and standard deviation of the run length. Finally, an example is used to illustrate the proposed control charts.     

A demerit-fuzzy rating system,monitoring scheme and classification for manufacturing processes

For monitoring online manufacturing processes, the proportion of weights imposed on each type of product’s defects (nonconformities or demerits) has a profoundly effective impact on control charts’ performance. Apparently, the demerit-chart approach is superior than the widely-used c-chart scheme, because it allows us to place relative precise weights (real numbers) on defects according to their distinctly inferior degrees affecting the product quality so that the abnormal variations of processes can be literally exposed. However, in many applications, the seriousness of defects is evaluated partially or entirely by the inspectors’ perceptive judgement or knowledge, so with the precise-weight assignment, the demerit rating mechanism is considered to be somewhat constrained and subjective which inevitably leads to the targeted manufacturing process with limited and possibly biased information for online surveillance. To cope with the drawback, a demerit-fuzzy rating system and monitoring scheme is proposed in this paper. We first incorporate fuzzy weights (fuzzy numbers) to properly reflect the severity measures of defects which are categorized linguistically. Then, based on properties of fuzzy set theory and proposed approaches for fuzzy-number ranking, we develop the demerit-fuzzy charting scheme which is capable of discriminating process conditions into multi-intermittent statuses between in-control and out-of-control. This approach improves the traditional process control techniques with the binary-classification restraint for the process conditions. Finally, the proposed demerit-fuzzy rating system, monitoring scheme, and classification is elucidated by an application in garment industry to monitor textile-stitching nonconformities conditions.     

辅锅控制程序在CENTUM-CS上的实现

全面介绍辅锅点火系统，从硬件配置、安全条件、点火逻辑和软件组态等几个方面论述辅锅控制程序的原理及其在CENTUM—CS上的实现方法，对CS系统的进一步开发利用具有较大的启发和借鉴作用。     

炼油厂循环水系统油料泄漏点快速检测

循环水系统内换热器中的油料泄漏在国内石化企业中是一个普遍存在的问题。由于循环水系统中换热器内漏的隐蔽性,泄漏时不能及时发现,从而造成油品的大量泄漏,造成对水冷设备的腐蚀,潜在地危害系统的正常运行,并给安全生产带来重大隐患。因此,研制一种能够及时识别泄漏物质及泄漏点的技术,对装置的安全生产以及长周期运行尤其重要。根据向量夹角法,用VB6.0编程自动完成分析两个液相谱图间的色谱峰匹配并计算相似度。结果表明,此方法能较好地定量评价液相图谱间的相似性,可应用于炼油厂循环水系统的漏点检测。     

面向软件密集型装备的软件过程度量和分析框架

软件密集型装备是武器装备发展的一个趋势。软件过程改进是提升嵌入软件的生产效率和质量的一种有效的改进手段。对于单个软件过程的控制和分析,由于传统Shewhart控制图无法区分其他过程对单个过程的影响,通过把系统因素进一步细分为外部系统因素和内部系统因素,使用选控图来隔离外部系统因素,实现对单个软件过程的独立分析。基于Petri网理论、故障树技术和模糊集理论,建立了适用于软件过程故障诊断的模糊Petri网模型。在此基础上提出针对单个软件过程的过程度量、控制、分析和改进框架。应用实例说明,在一定程度上,能够通过过程控制提升软件密集型装备的质量和生产效率。