Maintenance Models about A Plant of Three States

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A Multi-agent Framework of an Integrated Plant Maintenance System

Based on systematic analysis, an Integrated Plant Maintenance System (IPMS) is proposed in this paper to cope with challenges in plant maintenance. The characteristics of the IPMS are summarized and the necessity of its modeling is set forth. Based on the analysis and comparison among structured,object-oriented and multi-agent modeling frameworks, a multi-agent modeling framework is selected in this paper as a theoretical guidance and together with the Tropos method for modeling, the system model of an integrated plant maintenance system is constructed. The system model developed in this paper provides a guidance template for the Baling company in its stepwise implementation of the IPMS.     

可用度及动态维修成本下的维修决策模型

为了制定一个更具操作性、符合生产实际的设备维修计划,采用现代设备维修管理理论,考虑了预防维修成本的动态性,构建出一种以预防更新周期内单位时间总维修成本最小为优化目标,以设备可用度为约束条件的预防维修决策模型。通过引入算例,运用枚举法,借助Matlab仿真软件来验证模型的合理性,同时证明了企业可采用该种决策模型来实现其维修成本的最小化。     

Reliability‐based Optimal Maintenance Scheduling by Considering Maintenance Effect to Reduce Cost

A new reliability‐based optimal maintenance scheduling method is presented that considers the effect of maintenance in reducing costs. An ordering list of element maintenance effects with various maintenance‐interval types is constructed. By means of this ordering list, reliability‐based optimal maintenance scheduling for simple reliability structures and composite reliability systems is then carried out. The properties of the proposed method, such as the evaluation of maintenance cost reduction, the simplicity of the proposed method by sacrificing system availability within the allowance method, the operation decision based on the optimal maintenance schedule, etc., are discussed. With simulations, the effectiveness of the proposed method is verified. Copyright © 2005 John Wiley & Sons, Ltd.     

Multi-objective decision-making model based on CBM for an aircraft fleet with reliability constraint

Modern production management patterns, in which multi-unit (e.g. an aircraft fleet) are managed in a holistic manner, have brought new challenges for multi-unit maintenance decision-making. To schedule a good maintenance plan, not only does the individual aircraft maintenance have to be considered, but also the maintenance of the other aircraft in fleet have to be taken into account. Condition-based maintenance (CBM) is a maintenance scheme which recommends maintenance decisions according to equipment status collected by condition monitor over a period of time. Evaluating risk is necessary for scheduling appropriate maintenance, avoiding aircraft losses and maintaining the repairable components at a high-reliable state. In this paper, a novel two-models-fusion framework is proposed to predict the reliability of aircraft structures subjected to fatigue loads. Furthermore, we established a fleet maintenance decision-making model based on CBM for the maintenance of fatigue structures. The model concentrates on both minimising fleet maintenance cost and maximising fleet availability, overcoming the shortcomings of traditional fleet CBM research, which has simply focused on one or the other of these parameters. Finally, a case study regarding a fleet of 10 aircraft is conducted, and the results indicated that the proposed model efficiently generates outcomes that meet the schedule requirements.     

A Functional Inspection Model for the Immeasurable Potential Failure State

Functional inspection is a type of preventive maintenance of Reliability Centered Maintenance(RCM). We, in this paper, establish a functional inspection model(FIM)——the cost model and the availability model for the immeasurable potential failure state based on the delay time concept. This model can be used to determine the appropriate Functional Inspection Interval(FII) to achieve the goal of specific cost and availability and to assist in maintenance decision making.     

基于构造模型的植物形态建模

在对植物学家提出的23种植物构造模型及相关植物学研究的基础上,利用构造模型可以准确表达各种植物结构的特点,提出一种植物形态建模方法。该方法首先通过“构造”建立植物的拓扑结构和几何结构,再通过“渲染”处理和美化植物的三维结构。结合这种方法,在VisualC 环境下开发了相应的植物建模软件。文中给出的具体例子说明了该方法的可行性和有效性。     

The State of the Art of Hidden Markov Models for Predictive Maintenance of Diesel Engines

The maintenance of diesel Engines is usually scheduled according to the maintenance procedures defined by manufacturers. However, the state of the art shows that the condition monitoring maintenance associated with adequate prediction algorithms allows performance improvement both by increasing the intervals between interventions and by helping to maintain reliability levels. There are many types of variables that can be used to measure equipment condition, as is the case of several types of pollutant emissions such as NO_x, CO2, HC, PM, and NOISE, among others. This is a typical problem that can be solved through a hidden Markov model, taking into account the specificity of this type of equipment. The paper describes two algorithms that can help to increase the quality of assessment of engine states and the efficiency of maintenance planning. Those are the Viterbi and Baum–Welch algorithms. The importance of how to calculate the performance index of the model by the use of the perplexity algorithm is also emphasized. In this paper, a new paradigm is proposed, designated as ecological predictive maintenance. Copyright © 2017 John Wiley & Sons, Ltd.     

Optimum Maintenance and Availability of Series Systems Subject to Imperfect Repair

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Maximum Likelihood Estimation for a Hidden Semi‐Markov Model with Multivariate Observations

In this paper, a parameter estimation procedure for a condition‐based maintenance model under partial observations is presented. The deterioration process of the partially observable system is modeled as a continuous‐time homogeneous semi‐Markov process. The system can be in a healthy or unhealthy operational state, or in a failure state, and the sojourn time in the operational state follows a phase‐type distribution. Only the failure state is observable, whereas operational states are unobservable. Vector observations that are stochastically related to the system state are collected at equidistant sampling times. The objective is to determine maximum likelihood estimates of the model parameters using the Expectation–Maximization (EM) algorithm. We derive explicit formulae for both the pseudo likelihood function and the parameter updates in each iteration of the EM algorithm. A numerical example is developed to illustrate the efficiency of the estimation procedure. Copyright © 2012 John Wiley & Sons, Ltd.     

面向环境的设备维护管理与再制造工程集成模式

在分析再制造工程与设备维护管理的理论体系及二者关系的基础上,从有效利用资源、提升设备的使用效能的角度出发,运用质量功能展开(Quality Function Display,简称QFD)方法,提出了一种面向环境需求的设备维护管理和再制造工程的集成模式。     

家用植物生长箱的工业设计研究

针对城市经济发展过程中的环境污染、人们精神疲劳等问题,探究城市居民对绿色生活空间的需求,提出一种家庭植物生长箱产品的设计理念,将用户需求转化为细化的产品功能映射。基于工业设计的原则和方法,分析家用植物生长箱的操作对象、工作环境,给出其具体的设计尺寸。在此基础上,对植物生长箱进行工业设计,包括结构、造型、人机工程、色彩和材料等方面的产品设计过程。     

Proportional Intensity Models Robustness with Overhaul Intervals

The class of semi‐parametric proportional intensity (PI) models applies to recurrent failure event modeling for a repairable system with explanatory variables (covariates). Certain repairable systems (e.g. aircraft and electrical power generating plants) experience a substantial period of downtime due to performing maintenance (i.e. major overhaul) at scheduled intervals or following a major failure. Other systems (e.g. emergency power units) experience extended periods of non‐operating dormancy. These discontinuities in observation time have potential effects on the accuracy of estimation for covariate effects, particularly where calendar time is the life metric. This paper examines the robustness of two PI methods (Prentice–Williams–Peterson gap time (PWP‐GT) and Andersen–Gill (AG)) as a function of the overhaul or dormancy duration. The PWP‐GT model proves to perform well for sample size of 60 (30 per level of a class covariate), constant or moderately decreasing/increasing rate of occurrence of failures, and relative overhaul (dormancy) durations less than half of the immediately preceding interval between failures. The AG model performs consistently well for a small sample size of 20 (10 per level of a class covariate) for homogeneous Poisson processes, regardless of the relative overhaul (dormancy) duration. Copyright © 2005 John Wiley & Sons, Ltd.     

植物检疫行业标准制定中的质量风险分析

本文对标准制定中计划项目的确定、立项、起草、征求意见、审定和批准发布环节的质量风险进行了评估,提出了着力调整完善标准体系、建立起草人定量确定系统和建立标准起草顾问专家制度等三项风险控制管理措施,以保障植物检疫行业标准的质量,使其在植物检疫工作中发挥更大效能。     

A study of availability-centered preventive maintenance for multi-component systems

This paper studies preventive maintenance (PM) in simultaneously considering three actions, mechanical service, repair and replacement for a multi-components system based on availability. Mechanical service denotes the activities including lubricating, cleaning, checking and adjusting, etc. which is set to alleviate strength degradation. Repair is defined on that not only slow down the degraded velocity but also restore the degraded strength partly. Replacement is settled to recover a component to its original condition. According to the definitions, the degradation of components is analyzed from its failure mechanisms and the improvements of various actions to it in reliability were measured by using two improved factors. Following the proposed model of reliability, the mean-up and mean-down times of each component are also investigated and the replacement intervals of components are determined based on availability maximization. Here, the minimum one among the intervals is chosen as the PM interval of system for programming the periodical PM policy. The selection of action for the components on every PM stage is decided by maximizing system benefit in maintenance. Repeatedly, the scheduling is progressed step by step and is terminated until the system extended life reaching to its expected life. The complete schedule provides the information, the actions adopted for the components, the availability and the total cost of system on each stage. Validly, a multi-components system is used as an example to describe the proposed algorithm.     

Pairwise Meta-Modeling of Multivariate Output Computer Models Using Nonseparable Covariance Function

Gaussian process (GP) is a popular method for emulating deterministic computer simulation models. Its natural extension to computer models with multivariate outputs employs a multivariate Gaussian process (MGP) framework. Nevertheless, with significant increase in the number of design points and the number of model parameters, building an MGP model is a very challenging task. Under a general MGP model framework with nonseparable covariance functions, we propose an efficient meta-modeling approach featuring a pairwise model building scheme. The proposed method has excellent scalability even for a large number of output levels. Some properties of the proposed method have been investigated and its performance has been demonstrated through several numerical examples. Supplementary materials for this article are available online.     

Human Factors Effects and Analysis in Maintenance: A Power Plant Case Study

This paper proposes a methodical approach for identifying and reducing human error in maintenance activities, the human factors effect and analysis. Human factors effect and analysis presents a roadmap for selecting significant human factors affecting maintenance management as well as the most effective solutions using cost–benefit analysis. Safety and operational consequences of each human factor are compared to preventive and recovery risk controls to select the preferred risk control method. Because human factor programs are not implemented in many maintenance departments, quantitative data are rare. Thus, expert judgment may help to compare potential solutions. In order to show the applicability of the proposed approach a power plant in Kenya is selected as a case study. Procedure usage, fatigue, knowledge and experience, and time pressure are identified as the most important human factors. Training, task planning /shift management, knowledge management, scheduling as well as incident report programs are the most cost‐effective solutions for performing human factors program. The proposed approach would improve system reliability by recognizing human related failures. Furthermore, unexpected incident and accident may be reduced having knowledge about potential risk factors. Copyright © 2016 John Wiley & Sons, Ltd.     

基于植物多酚构筑新型功能材料

植物多酚是一类来源广泛的生物质材料,具有典型的生物活性和抗氧化性,还具有可吸收紫外线、可与金属离子螯合及可在化学反应中用作亲核试剂等多种功能与性质。植物多酚特殊的分子结构使其可以通过氢键、共价键、配位键、π-π堆叠等多种相互作用与其他分子结合,作为载体用于构筑各种功能材料。本文系统介绍了植物多酚的各种功能,讨论了近年来基于其功能性及化学反应性所开展的功能材料制备方面的研究进展,并展望了植物多酚这一类环境友好型生物质在功能材料制备方面的应用前景。     

基于局部环境敏感的动态植物建模研究

通过在L-系统中引入提问模块和剪枝函数,对植物剪枝后内部资源分配发生改变的情况进行L-系统建模,并通过仿真实验分别实现了一个二维空间的植物抽象发展过程和一个三维空间下的植物剪枝模型。实验表明,这种建模方式可以很好地模拟植物剪枝后的生长变化过程,对虚拟农林、虚拟园艺的研究有一定借鉴意义。     

多物流生产线系统的功能有效度分析

针对多物流生产线同时生产系统可靠性分析的难点及物流量预测不准确的问题，提出了准并联及功能有效度的概念，并分析得到了功能有效度的计算公式。为考虑物流的准并联系统的可靠性分析提供了科学的分析方法。