首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 99 毫秒
1.
企业设备会发生不同程度的缺陷,各类型缺陷造成的停机时间不同,应采取不同的维修类型.目前大多数的研究仅局限于确定单一类型缺陷的最优维修间隔期,不能同时确定出多种维修类型的间隔期,造成交货期比实际情况过长的问题,且他们的研究模型基本是以单位时间内的费用最低为优化目标的.基于此,本文首先阐述了多嵌套类型检查之间的关系,作出相应的假设,其次利用时间延迟理论求出了各种停机时间期望值的表达式,建立了以单位时间内故障停机时间期望值最小为目标的模型,并用数学方法求出了最优解,最后是案例分析,研究表明模型与实际情况比较接近,具有现实指导意义.  相似文献   

2.
多部件系统故障预防工作的组合优化   总被引:2,自引:0,他引:2  
研究了实践中常见的四种预防工作组合类型,即定时维修、功能检测、使用检查及检查与定时维修的组合策略,以单位时间维修费用最小为目标建立了多部件故障预防工作的组合优化模型.在此基础上,提出了两个故障预防工作的组合优化算法,并给出了计算示例以说明模型和算法的性能.  相似文献   

3.
可靠性和维修性的参数估计在可修系统建模及维修决策中具有非常重要的地位.不完全维修条件下可修系统的故障时间既不相等也不服从独立分布,这使得可修系统维修模型的参数估计变得十分困难.针对此问题,对第一次故障服从威布尔分布,故障之后进行Kijima类型I的修复性维修和Kijima类型I的预防性维修的可修系统进行了研究,应用贝叶斯分析对威布尔分布的形状参数β、尺度参数η、修复性维修的不完全维修因子ar以及预防性维修的不完全维修因子ap进行估计.仿真算例表明,该方法可以较为准确的对可靠性和维修性参数进行估计.  相似文献   

4.
传染病模型的研究及应用   总被引:1,自引:0,他引:1  
分析了传染病的传播扩散特点,建立了传染病传播扩散的微分方程模型.利用最大似然估计法对模型中的参数进行了估计.并以SARS传染扩散为例,利用网上的公开数据对模型进行了检验,所得结果与实际情况一致.此模型为传染病的预防和控制提供了理论依据.  相似文献   

5.
研究由两个不同型部件和一个修理工组成的冷贮备可修系统,其中部件1具有优先使用权.为了延长系统的工作时间,考虑对部件1进行非定期预防维修和故障维修相结合的维修策略,并以部件1的故障次数N和预防维修间隔T为二元维修策略(N,T),利用几何过程和更新过程等数学理论,建立以修理工单位时间内平均休假时间为目标函数、以费用率和平均停机时间为约束条件的优化模型,最后运用实例验证了模型的有效性.  相似文献   

6.
我国通讯产品扩散的模型分析   总被引:8,自引:0,他引:8  
利用Bass创新扩散模型描述我国无线寻呼和移动电话的扩散过程.通过对无线寻呼和移动电话的历史数据进行模型参数的估计,建立无线寻呼和移动电话的采用者扩散模型,分析无线寻呼被市场淘汰的原因和移动电话的市场前景.最后根据模型得出的结果对模型进行了讨论  相似文献   

7.
对恒定应力加速寿命试验建立了定时截尾与定数截尾参数模型.在诂计模型参数时,考虑定时截尾产品失效数的随机性,引入近似因子、修偏乘子和修偏项,建立起参数估计通用式并逐次进行跟随修偏估计.对定数截尾考虑数据信息随机性短缺,通过变量变换分别建立最优线性无偏估计和简单线性无偏估计在指数分布条件下的式子,并按统计分析考虑随机因数的影响引入综合修偏因子,按抽样数目的多少分别采用修偏后的式子.最后应用实际数据对模型参数逐次修偏估计和不同估计方法对比的最佳估计.  相似文献   

8.
为对基金净值数据进行建模,根据基金净值样本数据的尾部特点,建立极大,极小值分布的GPD模型,运用POT方法确定临界值,进而对参数进行估计,并对模型进行检验.最后,运用建立的模型对一些极值点进行预测.所得结果很好地描述了数据特点,对极值点的预测符合实际.  相似文献   

9.
针对生产过程输出质量特性服从正态分布的单部件延迟时间生产系统,研究了预防维修策略和X-bar控制图联合经济设计问题.首先,在将延迟时间系统界定为受控、失控、故障3种结果状态基本内容前提下,根据维修时系统可能存在的实际状态和控制图监测结果关系,分析构建了生产系统维修方式和控制图监测的耦合机制;在此基础上,以期望单位时间最小成本为目标,以系统维修成本、产品质量抽检成本、不合格品的生产费用、维修停机生产损失为考虑成本内容,利用更新过程理论建立了生产系统预防维修策略和X-bar控制图联合决策数学模型;然后基于数值仿真示例,利用遗传算法对模型的求解进行了分析验证.实例分析结果表明,文章模型可行有效.最后,利用部分因子试验设计方法对模型参数进行了敏感性分析.  相似文献   

10.
故障相关的表决可修系统可用度计算   总被引:1,自引:0,他引:1  
为解决k/n(F)表决可修系统中零部件的故障相关干涉问题,根据零部件工作寿命之间的正相关结构,运用Copula函数的相关性理论,提出微时间差t→t+Δt内系统一步状态转移矩阵概念,建立了故障相关的表决可修系统可靠性模型.模型全面考虑了共因故障、零件工作寿命和修复时间分布的一般性,从而突破传统独立指数型可修系统可靠性模型的三类局限性.验证了k/n(F)可修系统相关性模型的通用性,给出了Copula模型选择和估计相关程度参数的方法.  相似文献   

11.
In this paper we present a study carried out for a copper productsmanufacturing company, developing and applying the delay-timemodelling technique to model and thus optimize preventive maintenance(PM) of the plant. A key machine in the plant is used to illustratethe modelling process and management reaction. The parameter values of the process by which faults arise andof the delay-time distribution are estimated from maintenancerecord data of failures and faults found at PM, using the methodof maximum likelihood. A test of the model fit to data is carriedout. Based upon the estimated model parameters and the failuredelay time, an inspection model is proposed to describe therelationship between the total downtime and the PM interval.  相似文献   

12.
This paper presents a maintenance-modelling case study of aplant manufacturing brake linings. A delay–time modelis developed and applied to model and optimize preventive maintenance(PM). A key subsystem in the plant is used to illustrate themodelling process and management reaction. Defects identifiedat PM may not all be removed. This incomplete response to PMis a feature which has not been modelled before. The parametervalues of the delay-time process are estimated from objectivedata from maintenance records of failures, using the methodof maximum likelihood. This is aided by a theorem extendingresults on the NHPP arival rate of failures in a perfect-inspectioncase to the non-perfect-inspection case. Problems of parameterestimation given inadequate data collected at PMs are discussed,and the necessity to augment objective data with subjectiveassessments highlighted. Based upon the estimated model parametersand delay-time distribution, an inspection model is constructedto describe the relationship between the total unit downtimeand the PM interval. The response of management is discussed.  相似文献   

13.
This paper presents a case study of delay-time-based preventive maintenance (PM) modelling for a production plant system. Since production stoppages caused by waiting for raw materials provide windows to inspect and maintain the system, these production stoppages can be incorporated into the PM model. Considering the nature of different defects that can cause failures, two types of defects are modelled: small and large defects. Small defects are normally dealt with during production stoppages, but both small and large defects can be dealt with over a longer duration during PM. The parameters of the model are estimated using the maximum-likelihood method based on the real data. The model aims to find the optimal PM interval by minimizing the expected total downtime within an overhaul cycle. Management suggestions are also recommended.  相似文献   

14.
This paper develops an integrated model of production lot-sizing, maintenance and quality for considering the possibilities of inspection errors, preventive maintenance (PM) errors and minimal repairs for an imperfect production system with increasing hazard rates. In this study, a PM activity is imperfect in that a production system cannot be recovered as good as new and might cause the production system to shift to the out-of-control state with a certain probability. Numerical analyses are used to simulate the effect of changes in various parameters on the optimal solution for which the time that the process remains in the in-control state is assumed to follow a Weibull distribution. In addition, we investigate the effects of inspection errors and PM errors on the minimum total cost of the optimal inspection interval, inspection frequency and production quantity.  相似文献   

15.
In this paper we describe a subjective data based case study carried out at a company manufacturing copper products, which parallels a previously published objective data based study at the same plant. The purpose of this study is twofold. The first is to model the implementation of Planned Preventive Maintenance (PM) to an Extrusion Press using the delay time concept. The second is to test a method for estimation of model parameters from subjective data in the context of delay time modelling. The parameter values of the underlying fault arrival process and the delay time distribution were, unlike in a parallel objective study, initially estimated from subjective data obtained through a questionnaire survey. Since bias was present in the initial subjective estimate, a method of removing it was developed to improve the model fit. On the basis of the data analysis and delay time modelling, improved PM policy and procedures were proposed to increase the effectiveness and efficiency of PM.  相似文献   

16.
Spare parts demands are usually generated by the need of maintenance either preventively or at failures. These demands are difficult to predict based on historical data of past spare parts usages, and therefore, the optimal inventory control policy may be also difficult to obtain. However, it is well known that maintenance costs are related to the availability of spare parts and the penalty cost of unavailable spare parts consists of usually the cost of, for example, extended downtime for waiting the spare parts and the emergency expedition cost for acquiring the spare parts. On the other hand, proper planned maintenance intervention can reduce the number of failures and associated costs but its performance also depends on the availability of spare parts. This paper presents the joint optimisation for both the inventory control of the spare parts and the Preventive Maintenance (PM) inspection interval. The decision variables are the order interval, PM interval and order quantity. Because of the random nature of plant failures, stochastic cost models for spare parts inventory and maintenance are derived and an enumeration algorithm with stochastic dynamic programming is employed for finding the joint optimal solutions over a finite time horizon. The delay-time concept developed for inspection modelling is used to construct the probabilities of the number of failures and the number of the defective items identified at a PM epoch, which has not been used in this type of problems before. The inventory model follows a periodic review policy but with the demand governed by the need for spare parts due to maintenance. We demonstrate the developed model using a numerical example.  相似文献   

17.
A model is developed for the reliability of a single component, subject to one type of inspectable defect, which will subsequently lead to a failure. Inspections are assumed perfect. The model utilizes the notion of delay time to establish the reliability consequences of inspecting on different inspection periods. The argument is readily extended to the case of a component with multiple and independent defects. Numerical examples are provided.  相似文献   

18.
针对设备维修与备件管理相互影响与制约的问题, 在基于延迟时间理论的基础上, 提出了两阶段点检与备件订购策略联合优化。点检是不完美的, 当点检识别设备的缺陷状态时, 进行预防更新; 设备故障时, 进行故障更新。结合设备更新时备件的状态, 采用更新报酬理论建立了以第一阶段点检时间、第二阶段点检周期和备件订购时间为决策变量, 以最小化单位时间期望成本为目标的模型。最后, 通过人工蜂群算法对模型求解, 并在数值分析中将两阶段点检策略与定期点检策略进行比较, 结果表明:两阶段点检策略始终优于定期点检策略, 验证了所建模型的有效性。  相似文献   

19.
A periodic testing model for a preparedness system with a defective state   总被引:1,自引:0,他引:1  
This paper considers the periodic testing of a preparednesssystem where in addition to working and failed state recognition,a working but defective state also exists. Based upon the delaytime model, an expected availability model is derived and evaluatedas a function of the constant inspection period. The model enablesthe range of inspection periods which satisfy a pre-set availabilitycriterion to be established, and the optimal availability inspectionperiod to be identified. Variants of the basic model are considered including: wherea delay time period exists, but the technology to detect a defectis not available; where the delay time is zero, so that onlyfailures are detected; and where the system is replaced on aregular basis without any state testing. These variants enablethe value and effectiveness of the ability to detect defectsand to detect failures to be identified and quantified. The models are demonstrated in the context of a missile buffersystem, where the numerical example clarifies the value of modellingand the insight into the potential effectiveness of defect andfailure detection.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号