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1.
证明了年龄更换策略和成批更换策略依矩母函数序减少(增加)任意时间间隔内的失效次数的充要条件是基分布具有NBUMg(NWUMg)性质;更换间隔不同的成批更换策略在相同工作时间内的失效次数也作了比较。  相似文献   

2.
在介绍期望序和NBUE类分布的定义后,首先证明了年龄更换策略和成批更换策略的更换间隔依期望序分别大于正常更新过程的更换间隔的充要条件是基分布属于NBUE类.随后,还考察了参数不同的年龄更换策略之间和成批更换策略之间的更换间隔.  相似文献   

3.
针对自动化车床工序最优检测和刀具更换问题进行了探讨.将定期检测和将刀具更换作用于同一工序流程,在只考虑刀具故障条件下,通过概率论和更新过程理论建立了以单位时间内期望费用为目标函数的数学模型,以检测间隔和刀具更换间隔为策略,确定最优的策略使得目标函数达到最小,并求出了经长期运行单位时间内期望费用的明显表达式.最后还对结果进行了讨论.  相似文献   

4.
贺澜  孟宪云 《运筹与管理》2019,28(8):100-106
本文在截断δ-冲击模型的基础上,考虑了因系统劣化而导致的冲击失效门限值与维修时间的变化,扩充失效状态,从而提出一种新的截断δ-冲击模型。以最小费用为目标,稳态可用度为约束条件,建立N型更换策略的不完全维修更换策略模型,并给出三种常用冲击到达间隔分布的期望寿命。最后通过算例验证模型的有效性,并对参数进行灵敏度分析。  相似文献   

5.
在现有的诸更换模型的基础上,研究了一种备件有限及部件可修的更换策略问题。利用在更换周期点上具有马尔可夫性质,以系统故障前平均工作时间最大为目标建立了确定最佳更换周期的模型。  相似文献   

6.
将延迟几何过程进行推广并引入延迟α-幂过程,以用于处理退化过程会发生延迟且延迟发生的概率会随故障次数的增多而减小的系统.以系统的故障次数为更换策略,以平均费用率为目标函数,建立了维修更换模型,证明了最优维修更换策略的存在性.最后,通过一个数值例子验证了方法的有效性.  相似文献   

7.
本文讨论了一种具有一般δ-冲击的可修系统,我们不仅给出了该系统的一些可靠性指标,如系统的可靠度,系统平均工作时间,系统工作时间的极限分布等,而且对该可修系统的分布性质也进行了研究.在Poisson冲击下,我们证明了该系统的寿命分布是NBU的.在该系统为”修复非新”时,我们利用几何过程考虑了以系统的故障次数N为更换策略,以长期运行单位时间内的期望费用为目标函数,通过目标函数最小化确定了最优更换策略.最后我们给出了一个数值例子.  相似文献   

8.
将单阈值故障的δ-冲击模型推广为多阈值故障的情形,以用于处理不同的冲击间隔会导致不同程度故障的工程实际问题.在假设系统是退化的且有k个不同阈值的条件下,以降低系统的运行费用为目标,以部件故障次数N为更换策略,通过更新过程理论求得系统的平均费用率表达式.最后借助数值例子演示了本模型,并对相关参数进行了灵敏度分析.  相似文献   

9.
基于消费者对保修的需求,设计消费者偏爱的保修策略是制造商巩固市场地位、提升市场竞争力的一种战略决策。与此同时,以较低费用制定较长出保服役时间的出保维修策略也是消费者一直追求的目标。本文以两类失效产品为研究对象,首先从制造商角度将消费者偏爱的更新免费更换保修策略与产品定价相融合,开展了产品保修策略设计。其次,从消费者角度将预防维修与经典周期更换策略相融合,提出了维修—周期更换策略,且将其作为出保维修策略并对相应的性能进行了说明。通过数值实验发现,利润模型可对保修开展设计;与总费用模型作为目标函数相比,费用率模型作为目标函数可降低寿命周期费用;与经典周期更换策略相比,提出的维修—周期更换策略能使出保服役时间更长、费用率更低。  相似文献   

10.
将几何过程与PH分布相结合, 讨论一个带有位相型随机补货提前期的PH退化可修系统.通过建立最小生成元$Q$矩阵,获得了系统在稳态情形下的状态概率分布向量及其数值解.根据上述研究结果同时也得到了系统的几个重要可靠性指标. 进一步地,还考虑了基于部件故障次数的订购策略和更换策略,导出系统单位时间平均运行成本的解析表达式并给出一个确定最优$N$策略的数值算例.  相似文献   

11.
This paper investigates the effects of a free-repair warranty on the periodic replacement policy for a repairable product. Cost models are developed for both a warranted and a non-warranted product, and the corresponding optimal periodic replacement policies are derived such that the long-run expected cost rate is minimized. For a product with an increasing failure rate function, structural properties of these optimal policies are obtained. By comparing these optimal policies, we show that the optimal replacement period for a warranted product should be adjusted toward the end of the warranty period. Finally, examples are given to numerically illustrate the impact of a product warranty on the optimal periodic replacement policy.  相似文献   

12.
Adopting a proper cache document replacement policy is critical to the performance of a caching system. Among the existing cache document replacement policies, no one policy can surpass all the other policies in every case. Besides, the most suitable cache document replacement policy for a caching system is often chosen from the existing policies, which cannot guarantee the optimality of the chosen policy. These phenomena motivate us to construct a cache document replacement policy which content can be tailored to the specific requirements of a caching system. In this study, the optimal linear combination (OLC) cache document replacement policy tailored to the requirements of the caching system is to be found out. To evaluate the effectiveness of the proposed methodology, an experimental EC website has been constructed, and the log file of the website server was used as the data source to evaluate the performances of various cache document replacement policies under different cache sizes. In our simulation experiments, the OLC policies outperformed the other traditional policies by increasing the hit rate and the byte hit rate up to 7% and 11%, respectively.  相似文献   

13.
1. IntroductionMaintenance policies are followed to reduce the incidence of system failure or to returna failed system to the operating state. FOr example, if a component fails, one strategy isto replace it. Another strategy is not to wait for it to fail, but to replace it at some earIiertime, which belongs to maintenance poIicies problems. The most usefuI replacemeflt policiesare the age replacemeni policy and the block replacement policy. See [l,2] for a discussionof these policies. Compa…  相似文献   

14.
Under the generalized age replacement policy, the system is replaced either at the predetermined age or upon failure if its corresponding repair time exceeds the threshold, whichever comes first. In this paper, we investigate the optimal choice of the pre‐determined preventive replacement age for a nonwarranted system, which minimizes the expected cost rate during the life cycle of the system from the customer's perspective under certain cost structures. Furthermore, we discuss several properties of such a generalized age replacement policy in comparison with the traditional age replacement policy. An efficiency, which represents the fractional time that the system is on, is defined under the proposed generalized age replacement policy and its monotonicity properties are investigated as well. The main objective of this study is to investigate the advantageous features of the generalized age replacement policy over the traditional age replacement policy with regard to the availability of the repairable system. Assuming that the system deteriorates with age, we illustrate our proposed optimal policies numerically and observe the impact of relevant parameters on the optimal preventive replacement age.  相似文献   

15.
A system existing in a random environment receives shocks at random points of time. Each shock causes a random amount of damage which accumulates over time. A breakdown can occur only upon the occurrence of a shock according to a known failure probability function. Upon failure the system is replaced by a new identical one with a given cost. When the system is replaced before failure, a smaller cost is incurred. Thus, there is an incentive to attempt to replace the system before failure. The damage process is controlled by means of a maintenance policy which causes the accumulated damage to decrease at a known restoration rate. We introduce sufficient conditions under which an optimal replacement policy which minimizes the total expected discounted cost is a control limit policy. The relationship between the undiscounted case and the discounted case is examined. Finally, an example is given illustrating computational procedures.  相似文献   

16.
A deteriorating system with its repairman having multiple vacations   总被引:2,自引:0,他引:2  
This paper considers a repairable system with a repairman, who can take multiple vacations. If the system fails and the repairman is on vacation, it will wait for repair until the repairman is available. Assume that the system cannot be repaired “as good as new” after failures. Under these assumptions, using the geometric process and the supplementary variable technique, some important reliability indexes are derived, such as the system reliability, availability, rate of occurrence of failures, etc. According to the renewal reward theorem, the explicit expression of the expected profit per unit time is obtained. Finally, a numerical example is given to illustrate that there exists an optimal replacement policy N∗, which maximizes the value of the expected profit rate after a long time run.  相似文献   

17.
In this article, we consider a discrete-time order replacementproblem. More precisely, we treat a generalized model with morecomplex cost structure than Kaio & Osaki (1979, IEEE Trans.Reliab., R-29, 405–406) and with two decision variables:allowable inventory time and ordering time. Based on the discreteprobabilistic argument, we derive the optimal ordering policyto deliver a spare unit preventively by a regular order, soas to minimize the expected cost per unit time in the steadystate. Numerical examples are devoted to carrying out the sensitivityanalysis of model parameters on the optimal ordering policyand its associated expected cost value.  相似文献   

18.
胡必锦 《应用数学》2007,20(4):633-639
Das等研究过关于年代更换策略的一种简单模型[1,2],但这个模型不具有现实性.本文考虑的年代更换模型是具有现实意义的.在我们的模型中,元件的寿命T为"功能衰减"变量U和延时变量H之和,即T=U+H.在U和H满足某些条件下,可得出:T∈IFR的结论(引理1).此外,我们得到保证最佳年代更换策略的解的存在性与唯一性的充分条件,但不必要求T∈IFR(定理1).  相似文献   

19.
It is proved that a certain kind of randomly discounted random sums is asymptotically normal as the discount constant tends to zero. For replaceable systems with random lifetime, these sums represent the total discounted cost of policies of the age-replacement type; other applications to queueing and related areas are also indicated.  相似文献   

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