An economic production quantity model for deteriorating items with preventive maintenance policy and random machine breakdown

In recent years, many researches on economic production quantity (EPQ) models with machine breakdown and preventive maintenance have been developed, but few of them have developed integrated models for deteriorating items. In this study, we develop EPQ models for deteriorating items with preventive maintenance, random machine breakdown and immediate corrective action. Corrective and preventive maintenance times are assumed to be stochastic and the unfulfilled demands are lost sales. Two EPQ models of uniform distribution and exponential distribution of corrective and maintenance times are developed. An example and sensitivity analysis is given to illustrate the models. For the exponential distribution model, it is shown that the corrective time parameter is one of the most sensitive parameters to the optimal total cost.     

Intelligent decision-making model in preventive maintenance of asphalt pavement based on PSO-GRU neural network

The milage of asphalt pavement growth explosively around the world in the past decades resulted in a tremendous maintenance workload. Preventive maintenance (PM) is an effective strategy in saving budget, keeping the pavement in good condition, and extending pavement life. A particle swarm optimization (PSO) algorithm enhanced gated recurrent unit (GRU) neural network is developed in this research to predict five pavement performance parameters. The model is trained based on a dataset containing seven-year distress measurement data in 100-m intervals, traffic load data, climatic records, and maintenance records of a chosen highway in China. The random forest (RF) algorithm is used to analyze the influence of the factors on pavement performances for different lanes. The result shows the PSO-GRU model could increase the prediction accuracy by 21% on average compared with traditional ANN and 17% on average compared with the AdaBoost model. The validation case study shows a significant consistency between the predicted pavement quality index and the whole-year measurement data with a 0.67 coefficient of determination. This study demonstrates the potential of using the PSO-GRU neural network to provide the most effective treatment at a given location on a highway.     

一种ERP系统的远程维护系统

本文提出了一种通过Internet对ERP系统进行远程诊断和维护的系统。该系统能辅助维护人员快速找到问题的症结并进行相应的联机操作,并可通过自动识别补丁邮件和下载安装的方式对ERP系统进行更新。该系统能极大地节省维护和通信的时间及费用,且具有较好的实用性和通用性,文中对系统的功能、结构、工作机理以及实现的关键技术进行了阐述。     

基于贝叶斯网络的工业系统维护模型研究

为解决工业系统维护中的设备维护的预知性、适时性和合理性等问题,提出一种基于贝叶斯网络的工业系统维护模型。详细分析并介绍了建立系统维护模型的过程,利用贝叶斯网络解决不确定性问题的优势对问题推理、分析与定位,效果较好。通过应用示例,证明贝叶斯网络模型对工业系统维护实施,维护决策具有有效的指导作用。     

Layered distributed operating system

The improved efficiency of microelectronics and the development of digital transmission systems have allowed experimentation with distributed computing architectures. The requirements of a distributed operating system are outlined, and the principles and architecture used in the system are explained. A method is described of managing the system directories, and an analysis is given of the results obtained.     

A knowledge-based system for maintenance planning of highway concrete bridges

This paper presents a knowledge-based system that is used for maintenance planning of highway concrete bridges. The system includes functions for maintenance priority setting among bridges, feasible treatment assessment in each case, and maintenance planning for a bridge stock. Maintenance priorities are set using a scoring model with decision parameters appropriately weighted. Feasible treatments are determined based on bridge condition and other factors that accelerate deterioration. Decisions for maintenance planning result from a linear programming model and are based on priority ranking, cost and effectiveness characteristics of feasible treatments, and existing budget constraints. The system has been successfully evaluated with actual and simulated data.     

装备分布式虚拟维修训练云仿真关键技术

传统分布式虚拟维修训练系统仿真任务和仿真设备耦合度高,系统仿真效率低,扩展困难;同时,作为分布式交互支撑的高层体系结构(HLA)和运行支撑框架(RTI)仅适用于局域网络,无法实现大范围的仿真资源共享和维修协同互操作。借鉴云计算和云仿真思想,提出了一种应用于装备虚拟维修训练领域的云仿真体系结构和框架实现方案;研究了面向Web服务的广域网RTI组件层次化体系结构,设计了基于Web服务的仿真邦员,实现了仿真过程监控和远程邦员任务迁移功能;基于最小调度法实现了仿真平台的动态负载平衡,研究了平台的可视化仿真功能和仿真数据的分布式存储技术。在此基础上完成了某型装备的虚拟维修训练网络化仿真开发,初步证明了虚拟维修训练云仿真的可行性和有效性     

Solution of inverse boundary-value problems for multicomponent parabolic distributed systems

Computational algorithms implementing gradient methods based on solution of direct and adjoint problems in weak formulations are proposed for a number of complex-valued inverse problems of parameter renewal in multicomponent parabolic distributed systems. This approach makes it unnecessary to construct Lagrangian functionals explicitly and to use Green’s functions. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 49–73, July–August 2007.     

A preventive maintenance policy for a standby system subject to internal failures and external shocks with loss of units

In many situations, serious damage and considerable financial losses are caused by non-repairable failures of a system. Redundant systems and maintenance policies are commonly employed to improve reliability. This paper is focused on the modelling of a complex cold standby system by analysing the effectiveness and costs of preventive maintenance, always in an algorithmic form. The online unit of the system is subject to wear failures and external shocks. The online unit can go through an indeterminate number of degradation levels before failure. This one is observed when inspections occur. Inspections are performed at random intervals, and when one takes place, the unit is taken to the preventive maintenance facility if it is necessary. The preventive maintenance time and cost is different depending on the degradation level observed. If only one unit is performing, a minimal maintenance policy is adopted in order to optimise system behaviour. Reliability measures such as the conditional probability of failure are worked out in a well-structured and algebraic form in transient and stationary regimes by using algorithmic methods. The stationary distribution is calculated using matrix analytic methods, and rewards are included in the model. An optimisation example shows the versatility of the model presented.     

Review of rational (total) nonlinear dynamic system modelling,identification, and control

This paper is a summary of the research development in the rational (total) nonlinear dynamic modelling over the last two decades. Total nonlinear dynamic systems are defined as those where the model parameters and input (controller outputs) are subject to nonlinear to the output. Previously, this class of models has been known as rational models, which is a model that can be considered to belong to the nonlinear autoregressive moving average with exogenous input (NARMAX) model subset and is an extension of the well-known polynomial NARMAX model. The justification for using the rational model is that it provides a very concise and parsimonious representation for highly complex nonlinear dynamic systems and has excellent interpolatory and extrapolatory properties. However, model identification and controller design are much more challenging compared to the polynomial models. This has been a new and fascinating research trend in the area of mathematical modelling, control, and applications, but still within a limited research community. This paper brings several representative algorithms together, developed by the authors and their colleagues, to form an easily referenced archive for promotion of the awareness, tutorial, applications, and even further research expansion.     

广播电视系统状态维护技术初探

随着广播电视技术发展速度的不断加快,人们对广播电视的质量提出了较高的要求,而对广播电视系统的维修管理和电视质量的提高具有重要的保障作用.本文首先对广播电视系统状态维护技术的预测性维修和可靠性评估等内容进行了简要阐述,然后从系统构建的详细设计两个方面对广播电视系统状态维护技术进行了初次探究.     

基于性能合同的多部件系统维修策略模型优化

针对多部件串联系统维修效率低下与供应商所获利润少的问题,考虑各部件间的经济相关性,提出基于性能合同的多部件系统的维修策略模型.首先,采用韦伯(Weibull)分布描述系统各部件的使用寿命规律,并通过判断各部件使用度与预防性维修阈值和机会维修阈值的关系来实施不同的维修策略;其次,计算单位更新周期内的各维修活动概率和对应维...     

计算机辅助RCM分析系统数据库的研究与开发

从装备的RCM分析需求出发,讨论了计算机辅助RCM分析系统的功能及其构成,重点对其中RCM分析数据库系统的功能、组成以及建库过程进行了详细阐述,在此基础上提出了开发RCM分析数据库系统的基本思路。     

扩展服务路由器操作维护系统的研究

路由器操作维护(operating and maintenance,简称OAM)系统负责对路由器进行操作和管理.它是路由器正常运行的保证,是路由器中的重要模块.随着路由器技术的发展,对路由器软件动态升级的要求越来越受到人们的重视.对扩展服务路由器操作管理进行了深入的研究,首先介绍了扩展服务路由器操作管理的设计要求和研究现状,然后介绍了清华大学研制的扩展服务路由器原型系统的软、硬件体系结构及其对操作维护系统的功能要求,设计并实现了可实时动态加载扩展服务组件的操作维护管理系统.最后指出了进一步的研究方向.     

基于短消息平台的气象卫星业务维护管理系统

为满足静止气象卫星地面应用系统的运行管理需求,保证业务系统的高可靠性和维护响应的高时效性,设计了一套基于短消息平台的业务维护管理系统。该系统由短消息平台、实时业务监测和自动维护管理三部分组成,能够实时监测多套卫星系统的业务关键点,及时发现业务故障和特殊事件,利用短消息平台实现消息的集中管理和即时发送,同时具备故障策略管理、维护调度管理和自动化维护响应等功能。实施效果表明该系统具备良好的适用性和可扩展性,能有效减轻维护管理人员的工作压力,为高时效和高可靠要求的大型系统维护管理工作提供有效的技术手段。     

面向拆装训练的输油泵机组虚拟维修系统设计

针对输油泵机组实装维修训练存在的不足,设计了面向拆卸与装配训练的输油泵机组虚拟维修系统。通过现有主流虚拟现实仿真平台的对比,选择以Unity3D作为开发平台。分析了系统功能、性能需求,设计了系统多层次模块化训练体系结构。针对系统交互式拆装的核心功能需求,提出一种高效的鼠标拖拽时零部件位置更新算法;为在虚拟训练过程中正确模拟机械零部件拆装的顺序关系,研究了基于事件驱动编程的设计方法。对系统实际运行参数进行测试,满足各项功能、性能需求。系统不仅满足输油泵机组维修训练的需求,还可为其它产品的维修拆装训练系统设计提供参考。     

Subsea Maintenance Service Delivery： Mapping Factors Influencing Scheduled Service Duration

The oil and gas (O&G) industry on the Norwegian continental shelf (NCS) leads the world in terms of the number of subsea O&G installations. Ensuring the dependability of these assets is critical. Non-intrusive inspection, maintenance and repair (IMR) services are therefore needed to reduce risks. These services are planned and executed using a mono-hull offshore vessel complete with remotely operated vehicles (ROVs), a module handling system and an active heave compensated crane. Vessel time is shared between competing jobs, using a prioritized forward-looking schedule. Extension in planned job duration may have an impact on O&G production, service costs and health, safety, and environmental (HSE) risks. This paper maps factors influencing the job schedule efficiency. The influence factors are identified through reviews of literature as well as interviews with experts in one of the large IMR subsea service providers active on the Norwegian Continental Shelf. The findings show that the most obvious factors are weather disruption and water depth. Other factors include job complexity, job uncertainty, IMR equipment availability, as well as the mix of job complexity.     

The scheduling of maintenance. A resource-constraints mixed integer linear programming model

The scheduling of preventive maintenance is crucial in reliability and maintenance engineering. Hundreds of parts compose complex machines that require replacement and/or repairing. Maintenance involves the machine vendor (1), the machine user (2) and the service maintenance provider (3). The vendor and the maintenance service provider have to guarantee a high level of availability and productivity of the machines and maintain their down-time at a minimum even though they are installed worldwide and usually far from the vendor’s headquarters and/or the locations of the provider’s regional service offices. Moreover, many companies have great profits from maintenance and spare parts management.This study aims to illustrate an original mixed integer linear programming (MILP) model for the cost-based, reliability-based and resource-constraints scheduling of preventive maintenance actions. The model minimizes the total cost function made of spare parts contributions, the cost of the execution of the preventive actions and the cost of the additional repair activity in case of unplanned failure. The cost of the personnel of the producer and/or the maintenance service provider is also included. Finally, the paper presents a case study in a what-if environment demonstrating the effectiveness and the novelty of this study in real and complex applications.     

基于BP神经网络的维修任务优先级分类方法

在任务执行期合理、科学地确定维修任务的优先级别对于有序、高效地组织维修保障活动具有重要意义。提出了一种基于BP神经网络的维修任务优先级分类方法。详细介绍了神经网络模型的建模过程,其中重点介绍了模型设计,包括输入数据准备、输出数据准备与神经网络结构。所建立的神经网络模型通过对输入与输出的训练,可以学习准则与维修任务优先级之间的复杂关系,获得并表示决策者的偏好,有效地辅助决策者对维修任务优先级进行分类。     

面向健康管理的复杂装备维修模糊聚类

科学合理的维修活动是提高装备效能、提升部队战斗力的重要途径。装备复杂化、系统化,对可靠性、维修性、保障性要求越来越高,装备何时维修,采取何种策略,是装备效能发挥的重要前提。从健康管理角度出发,在分析健康状态、故障模式影响以及故障模式发生概率基础上,采取模糊C均值聚类法研究装备维修活动,科学划分维修时机并给出相应维修策略,从而优化装备维修活动,实现装备健康管理(EHM)目标。将所提方法应用于某型装备,并通过Matlab仿真,验证了方法的可行性与合理性,为装备健康管理提供决策依据。