电磁场有限元节点编号优化的两种方法

本文对电磁场有限元节点编号优化的两种有效方法－ＲＣＭ法和ＧＰＳ法，进行了分析和比较，给出了实施ＧＰＳ法的一些具体方式，提出了寻找伪直径端点和进行编号的改进方案。     

改进的PACT算法在RC网络约简中的应用

超大规模集成电路设计进入深亚微米阶段，衬底和互连线的寄生RC参数成为影响电路速度和信号完整性分析的关键因素．由于互连提取的RC规模十分庞大，对其进行时序分析十分困难，因此需要对提取的RC网络进行约简．在经典的RC网络约简算法PACT的基础上提出几点重要改进，明显地提高了网络约简的速度，改进后的算法克服了经典PACT算法的局限性，使之可以适用于含有到端口无直流通路的内点的电路，从而提高了该算法的适用性．计算结果表明，在精度保持不变的条件下，文中算法比经典的PACT算法约快几倍．     

Detection of equipment aging and determination of the efficiency of a corrective measure

When too many failures occur on a given piece of equipment, the dependability engineer needs to decide whether these failures are attributable to poor initial design or if they are due to a phenomenon of aging. If aging is confirmed, the problem is then to determine the moment at which the process began and what corrective measure (generally, a modification in the design or in the preventive maintenance program) is the best suited to delay the occurrence of the failure. This measure will thus make it possible to extend the lifetime of the equipment.The method is based on the simple hypothesis of a model of step aging and on Bayesian techniques.The principal benefit of this method is the determination of the time at which aging begins (and the related uncertainties), the evolution in the failure rate of the component in its initial state and once modified, and the probability of success of the corrective measure. The IBTV software was developed to implement this methodology.     

基于模糊数学的电站设备故障风险定量研究

在大型电站关键设备以可靠性为中心的状态检修定性分析中会发现其零部件有众多的故障模式.为了提高电站设备的安全性和可靠性,需要将重要的故障模式从大量的故障模式中挑选出来,以集中有限人力、物力优先处理这些重要的故障模式,从而以最小代价获得最大的经济效益.该文在对故障模式、影响及危害度定性分析的基础上,结合模糊数学,以故障影响严重度、故障模式发生概率和可检测性为关键指标,提出电站设备故障风险定量评价方法,即模糊推理法,并以电站风机为例详细阐述如何运用模糊推理法定量评价故障风险的过程.     

A hybrid methodology for enhancing reliability of large systems in conceptual design and its application to the design of a multiphase flow station

This paper presents a hybrid methodology for conceptual design of large systems with the goal of enhancing system reliability. It integrates the features of several design methodologies and maintenance planning concepts with the traditional reliability analysis. The methodology considers the temporal quality characteristic “reliability” as the main objective and determines the optimal system design. Key ideas from several design methodologies, namely axiomatic design, robust design, and the theory of inventive problem solving, have been integrated with the functional prioritization framework provided by reliability-centered maintenance. A case study of the conceptual design of a multiphase pumping station for crude oil production is presented. The methodology provides a new design tool for determining system configurations with enhanced reliability taking into account maintenance resources and variability.     

RCM在发电设备维护管理的应用探讨

分析了设备维护技术的发展状况，讨论了以可靠性为中心的理论-RCM研究的关键问题和内容，针对电厂设备维护要求和现状，进行了实施条件的分析，提出了电厂RCM实施的工作模式和步骤，并给出了典型电厂的可靠性节点分布图。     

基于(石化装置)系统RBI-SIL分析的承压设备完整性评估技术

石化装置中,静设备、动设备及仪表联锁是构成石化系统的三个重要组成部分,它们既能各自构建独立的体系,但又存在着密不可分的相互作用、风险传递关系。基于风险的管理(RBM)中,基于风险的检验(RBI)、以可靠性为中心的维护(RCM)与安全联锁完整性等级评估(SIL)涵盖了对静、动、仪的风险评估,但大量的实践表明,系统的失效是静设备、动设备与仪表联锁三个体系中某一环节的非正常动作,通过工艺介质的风险传递、扩大并相互作用,最终导致了承压类设备的失效,因此,简单、单一地对装置进行逐个评估,未必能覆盖系统中所有的失效可能。提出了一种基于石化装置系统RBI-SIL分析的承压设备完整性评估技术构思,其目的是可以更有效、更精确地评估系统风险,寻找系统产生风险的源头,制定更有效、优化的降险措施,尽可能地预防这种风险传递而导致承压设备失效事件的发生。     

Gas-phase saturation and evaporative cooling effects during wet compression of a fuel aerosol under RCM conditions

Wet compression of a fuel aerosol has been proposed as a means of creating gas-phase mixtures of involatile diesel-representative fuels and oxidizer + diluent gases for rapid compression machine (RCM) experiments. The use of high concentration aerosols (e.g., ∼0.1 mL_fuel/L_gas, ∼1 × 10⁹ droplets/L_gas for stoichiometric fuel loading at ambient conditions) can result in droplet–droplet interactions which lead to significant gas-phase fuel saturation and evaporative cooling during the volumetric compression process. In addition, localized stratification (i.e., on the droplet scale) of the fuel vapor and of temperature can lead to non-homogeneous reaction and heat release processes – features which could prevent adequate segregation of the underlying chemical kinetic rates from rates of physical transport. These characteristics are dependent on many factors including physical parameters such as overall fuel loading and initial droplet size relative to the compression rate, as well as fuel and diluent properties such as the boiling curve, vaporization enthalpy, heat capacity, and mass and thermal diffusivities. This study investigates the physical issues, especially fuel saturation and evaporative cooling effects, using a spherically-symmetric, single-droplet wet compression model. n-Dodecane is used as the fuel with the gas containing 21% O₂ and 79% N₂. An overall compression time and compression ratio of 15.3 ms and 13.4 are used, respectively. It is found that smaller droplets (d₀ ∼ 2–3 μm) are more affected by ‘far-field’ saturation and cooling effects, while larger droplets (d₀ ∼ 14 μm) result in greater localized stratification of the gas-phase due to the larger diffusion distances for heat and mass transport. Vaporization of larger droplets is more affected by the volumetric compression process since evaporation requires more time to be completed even at the same overall fuel loading. All of the cases explored here yield greater compositional stratification than thermal stratification due to the high Lewis numbers of the fuel–air mixtures (Le_g ∼ 3.8).     

当前工程机械维修存在的主要问题及解决方法

本文系统分析了当前工程机械维修的发展状况及存在的主要问题,结合研究现状,提出了改进对策及将RCM模式引入工程机械维修的建议.     

有关“简化的”RCM的剖析

"以可靠性为中心的维修(RCM)"这-术语始见于1978年,指的是美国民航业所研究出的一种非常具体的决策制定方法.RCM在民航业中取得了令入瞩目的成就,主要表现为提高了安全性和可靠性,并增进了维修的费用效果.从20世纪80年代初开始,其他的许多行业也由于推行RCM而取得了同样的成果.在此期间,RCM方法本身也在两个基本方面有所演变.一是仍然忠实于原先在航空业中所采用的严格方法,只是增添了某些为充分表征1978年就已提出的关键设备性能所需的特性(诸如与环境的一体性和以量化方式表示的风险).目前,RCM的发展所达到的现代水平均具体体现在美国汽车工程师学会制订的标准SAE Standard JA1011中.二是寻找可减少实施RCM所需的时间和精力的根本途径(尽管运用真正的RCM时通常都要经过数月或至少数周之后方能取得回报).这种做法是试图通过略去RCM方法中的某些部分或者所研究系统中的某些部分,或者双管齐下地将RCM予以"简化".在本文中,作者从技术的严谨性、风险和产生的结果是否站得住脚等方面,对这种"走捷径的高招"表示了极大的怀疑.