Optimizing maintenance of a serial-structure system depending on the operation time of each element

A semi-Markovian model of a system with serial structure is developed. The model accounts for the nonfailure-operation time of each element. Stationary reliable and economic performance characteristics of the system are found, and optimal terms of maintenance are determined. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 126–135, November–December 2006.     

A model for preventive maintenance operations and forecasting

Equipment costs constitute the greatest majority of overall costs for semiconductor manufacturing. Therefore, maintaining high equipment availability has been regarded as one of the major goals in the industry. The ability to forecast correctly equipment preventive maintenance (PM) timing requirements not only can help optimizing equipment uptime but also minimizing negative impacts on manufacturing production efficiency. This research used grey theory and evaluation diagnosis to construct a PM forecasting model for prediction of PM timing of various machines. The results showed significant improvements of PM timing predictions compared to the existing method based on experience and an alternative method proposed by Li and Chang (Semiconductor Manufacturing Technology Workshop 2002: 10–11, pp. 275–277) for the same fab cases. Received: June 2005 / Accepted: December 2005     

Reliability of engineering systems with combined performance control

The paper determines an optimal performance-check rule that maximizes the availability factor of a system subject to two types of failures. Long-use systems are considered such that timely intervention of maintenance staff is possible to make the system serviceable. Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 96–105, November–December 2008.     

大型暂冲式风洞自主式维修保障系统研究

2.4米×2.4米暂冲式风洞长期面临着繁重的试验任务,部分设备经常处于超负荷运行状态,故障频次、维修负担也逐年加重。为了解决风洞试修矛盾,提升风洞试验能力,本文基于故障预测与健康管理技术,针对2.4米×2.4米暂冲式风洞的运行和保障需求,结合风洞装备管理业务流程,从数据采集、数据存储、数据分析、数据应用这四个工作流程出发设计了系统软硬件架构,最终搭建了大型暂冲式风洞自主式维修保障系统。实现对故障的实时监测、诊断、预测。经过系统运行实践证明,风洞设备的故障率显著降低,试验能力和效率提升明显,初步建立了风洞的视情维修保障体系。     

某型战车信息终端仿真器的设计

针对装备维修训练中存在的装备结构复杂,价格昂贵,维修训练成本高的问题;设计了一个用于装备维修训练的信息终端仿真器;以某型战车驾驶员任务终端的内部结构、工作原理、信号特征和维修流程为依据,采用仿真技术、嵌入式设计技术等,重新设计与实物相似的终端仿真器,并以该仿真器为核心,辅以信号发生器及上位机等软硬件设备构造用于维修训练的仿真平台;该仿真器可进行信息终端的内部构造原理认知、维修过程训练和训练结果评估,应用表明该仿真器可满足装备维修教学和培训需求,提高维修人员的维修技能水平。     

(n,N) type maintenance policy for multi-component systems with failure interactions

This paper studies maintenance policies for multi-component systems in which failure interactions and opportunistic maintenance (OM) involve. This maintenance problem can be formulated as a Markov decision process (MDP). However, since an action set and state space in MDP exponentially expand as the number of components increase, traditional approaches are computationally intractable. To deal with curse of dimensionality, we decompose such a multi-component system into mutually influential single-component systems. Each single-component system is formulated as an MDP with the objective of minimising its long-run average maintenance cost. Under some reasonable assumptions, we prove the existence of the optimal (n, N) type policy for a single-component system. An algorithm to obtain the optimal (n, N) type policy is also proposed. Based on the proposed algorithm, we develop an iterative approximation algorithm to obtain an acceptable maintenance policy for a multi-component system. Numerical examples find that failure interactions and OM pose significant effects on a maintenance policy.     

Optimizing a multiserver queuing system with a variable number of servers

A multiserver Poisson queuing system with losses, with a variable number of servers, and an additive quality functional is investigated. All major characteristic of the system are obtained in an explicit form. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 92–101, July–August 2007.     

Algorithm for construction of parametric vectors for solution of classification problems by a feed-forward neural network

A universal heuristic algorithm is considered that constructs the vector of properties of an object that are distributed among heterogeneous groups. This algorithm is based on a feed-forward neural network. An automatic system for objects classification is described. The use of the automatic classification system for a literary authorship attribution problem is considered. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 3–14, March–April 2007.     

Parameter’s setting of the ant colony algorithm applied in preventive maintenance optimization

Meta-heuristic applications have evolved a lot nowadays and have been used in many domains. However, their parameter setting stills, till now, a serious problem which influences their efficiency and their attitude. Under the title of preventive maintenance optimization, the Ant Colony (AC) is used as a search technique for the best intervention dates to preventively maintain a series-parallel system. The AC proves once again its efficiency (Samrout, M., Yalaoui, F., Chatelet, E., & Chebbo, N. (2005). Reliability Engineering & System Safety, 89, 346–354), but the parameter setting’s issue persists as a critical issue which needs more analysis. This paper offers a detailed study about the influence of the parameters on the AC operation. An experimental plan design is done. Obtained results are coherent with the convergence conditions of the ant colony algorithms. Based on those latter, improvements are done to the original ant colony algorithm and interesting results are obtained.     

Combined production-maintenance decisions in situations with process deterioration

This article addresses an imperfect production system with process deterioration and how best to maintain the system. In the system there is a constant percentage to produce defective products in the ‘in-control’ state and a higher percentage to produce defective products in the ‘out-of-control’ state. The production process may shift randomly from an in-control state to an out-of-control state during a production run; i.e. system process deterioration. This article considers both preventive maintenance and corrective maintenance. The objective is to determine the optimal production run time and preventive maintenance frequency while still minimising the total annual cost. We provide two efficient algorithms for solving the problems when considering the preventive maintenance frequency as discrete and continuous, respectively. Finally, we apply a numerical analysis to study the effects of changing parameter values on the optimal solutions and to point out some management implications.     

Availability optimisation of repairable system with preventive maintenance policy

This article investigates optimal steady availability of a repairable system with six states. Both preventive maintenance and corrective maintenance are considered in this article. By probability argument, the system is described as an abstract Cauchy problem. Using the method of strong continuous semi-group theory, we derive the steady availability of the system. Finally, the optimal time to carry out preventive maintenance is analysed theoretically and numerical examples are presented.     

沉浸式虚拟维修仿真及其应用

文中给出了沉浸式虚拟维修仿真系统的框架,从样机建模和交互技术两个方面对其关键技术进行了研究。提出了虚拟维修样机的概念,通过定义样机部件的约束运动和交互特征来实现其要求的功能。而交互技术则主要集中在抓取、运动控制和防穿越处理上。对系统在维修性设计分析(核查)、维修程序确认和辅助维修训练中的应用进行了说明。建立了基于Jack系统的沉浸式虚拟维修仿真原型系统,并以某机构的拆装为例对其进行了初步的应用验证。     

Two-stage Maintenance of a Production System with Exponentially Distributed On- and Off-periods

We consider an on–off production system which is subject to failure during on-periods. In case of a failure, the production system is maintained correctively. In addition, preventive maintenance is carried out to prevent failures. The costs of both preventive and corrective maintenance are modelled in terms of the net down-time of the production system, that is, the time that the system is not available when needed for production. Since preventive maintenance can be planned during off-periods, there is a perspective of significant savings if some freedom is built in concerning the starting time of preventive maintenance. Therefore, a two-stage maintenance policy is considered, which—in a first stage—provides the maintenance manager with a finite interval during which preventive maintenance must be carried out, and—in a second stage—determines the optimal starting time for preventive maintenance within this interval. Computational results offer useful insights, and indicate that significant savings can be achieved in comparison with a classical age maintenance policy.     

On the numerical solution of nonlinear systems of Volterra integro-differential equations with delay arguments

Particular cases of nonlinear systems of delay Volterra integro-differential equations (denoted by DVIDEs) with constant delay τ > 0, arise in mathematical modelling of ‘predator–prey’ dynamics in Ecology. In this paper, we give an analysis of the global convergence and local superconvergence properties of piecewise polynomial collocation for systems of this type. Then, from the perspective of applied mathematics, we consider the Volterra’s integro-differential system of ‘predator–prey’ dynamics arising in Ecology. We analyze the numerical issues of the introduced collocation method applied to the ‘predator–prey’ system and confirm that we can achieve the expected theoretical orders of convergence.      

沉浸式虚拟维修仿真系统及其实现

给出了沉浸式虚拟维修仿真系统的框架,从样机建模和交互技术两个方面对其关键技术进行了研究．提出了虚拟维修样机的概念,通过定义样机部件的约束运动和交互特征来实现其所要求功能,而交互技术则主要集中在抓取和防穿越处理上．建立了基于Jack系统的沉浸式虚拟维修仿真原型系统,并以某机构的拆装为例对其进行了初步的应用验证。     

Foundations of programmology

An explication of the intuitive concept of programming is given in the form of explicative programming, which is a modern form of composition programming. It is based on a pragmatically finite system of principles. On this basis, an explication of the concept of composition is obtained. A hierarchical composition structure of programmology is constructed. Translated from Kibemetika i Sistemnyi Analiz, No. 1, pp. 35–57, January–February, 2000.     

Invariance theorems for a class of systems of random nonlinear equations over an arbitrary finite ring with left unity

A class of homogenous systems of random nonlinear equations over an arbitrary finite ring with left unity is considered. The author analyzes the invariance boundaries for limit factorial moments of nonzero solutions, the limit distribution of the number of nonzero solutions, and the geometrical structure of the set of nonzero solutions of the system as the number of unknowns tends to infinity. Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 106–115, November–December 2008.     

Deductive tools of an algebraic programming system

A mathematical environment is a system of tools supporting interactive manipulation of knowledge represented in the form of (formalized) mathematical texts. A theoretical substantiation of a project proposed is the theory of interaction of agents and environments. At the present time, this theory is realized on the basis of a simulator of an action language developed in an algebraic programming system called APS. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 17–34, January–February, 2000.     

Application of a Neural Fuzzy System with Rule Extraction to Fault Detection and Diagnosis

In this paper, the fuzzy min–max (FMM) neural network is integrated with a rule extraction algorithm, and the resulting network is applied to a real-world fault detection and diagnosis task in complex industrial processes. With the rule extraction capability, the FMM network is able to overcome the “black-box” phenomenon by justifying its predictions using fuzzy if–then rules that are comprehensible to domain users. To assess the effectiveness of the FMM network, real sensor measurements are collected and used for detecting and diagnosing the heat transfer and tube blockage conditions of a circulating water (CW) system in a power generation plant. The FMM network parameters are systematically varied and tested, with the results explained. Bootstrapping is employed to quantify stability of the network performance statistically. The extracted rules are found to be compatible with the domain information as well as the opinions of domain experts who are involved in the maintenance of the CW system. Implications of the FMM network with the rule extraction facility as an intelligent and useful fault detection and diagnosis tool are discussed.     

Maintenance strategy for leased equipment

In case of leasing, the user rents equipment for a predetermined time. During this period, all maintenance actions are performed by the lessor. The aim of this research paper consists in determining an optimal maintenance policy for ensuring a minimum reliability, required by the customer. Two strategies are proposed: the first consists in performing preventive actions whenever the system reliability reaches a predefined reliability threshold. These actions are characterized by a reduction of the system age. The objective is therefore to determine the effectiveness factor of the optimal maintenance minimizing maintenance costs. For the second strategy, “improving” actions replace corrective actions during an interval to be determined to minimize maintenance costs. The first strategy will be solved using a numerical procedure and the second strategy uses an algorithm of discrete event simulation.