This paper consideres an optimal ordering and replacement problem of a continuous time Markovian degradation system. An optimal policy minimizes the expected cost per unit time in an infinite time horizon. The problem is formulated by semi-Markov decision process and the optimality of an (n,N)-policy is shown. Further, the expected cost rate of the system operated under an (n,N)-policy is obtained.
We consider an optimal ordering and replacement policy of a discrete time Markovian deterioration system when the observation of the system is incomplete. The problem is to examine the structure of an optimal policy which minimizes the total expected discounted cost in an infinite time span. Formulating by a Markovian decision process, the optimality of a monotone policy is shown under some conditions on the deterioration system. Furthermore, some special cases are discussed.
Let D be a distributive lattice formed by subsets of a finite set E with φ, E ∈ D and let R be the set of' reals. Also let f be a submodular function from D into R with f(φ) = 0. We determine the set of extreme points of the base polyhedron [numerical formula] and give upper and lower bounds of f which can be obtained in polynomial time in |E| under mild assumptions.
This paper reports on the findings in an empirical study of 92 OR/MS projects with the aim of identifying the effect of participation of concerned parties on the success of project wherein project types are considered in terms of the "newness" (innovativeness) of approach used. CLIENT, OR/MS and OTHERS who have stake i_n the project are considered to constitute concerned parties. Data were gathered for each of the five phases of the progress of project . It was shown that the degree of participation of concerned parties had significant effect on the success of OR/MS projects. Further, participation of client group throughout the five phases of project progress was found to be particularly important in the innovative type projects while it was necessary in both the planning and the validating phases in the case of non-innovative type projects. The projects initiated by the leadership of clients had the highest: success rate.
This paper treats the replacement problems with incomplete repairs. In many papers, replacement problems have been studied under the assumption of minimal repairs or complete repairs, and not considered the number of failures as the deteriorating measure of units. In this paper, we introduce and formalize some basic model as an approach to that case. In the basic modcl it is shown that a non-randomized policy is optimal.
A phenomenon of certainty effect is well known as a typical paradox in expected utility theory and is often observed in the laboratory gambling to test the axiomatic system of utility theory. A necessary and sufficient condition that the certainty effect is observed is demonstrated by means of a generalized utility function and some properties of individual's behavior derived from the condition are discussed.