摘要:

AbstractA system is subject to a sequence of randomly occurring shocks. Each shock causes a random amount of damage which accumulates additively. Any of the shocks might cause the system to fail. The shock process is in some sense related to an environmental process in order to describe randomly varying external factors of an economical and/or technical nature as well as internal factors of a statistical nature. A discrete time formulation of the problem is given. Sufficient conditions are found for optimality of a generalized control‐limit rule with respect to the total cost criterion: Whenever the accumulated damagesis not less than a specified critical numbert(i), depending on the environmental statei, replace the system by a new one; otherwise do not replace it. Moreover, bounds are given for these critical number

ISSN:0028-1441    

DOI:10.1002/nav.3800300302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractDecomposition algorithms for finding a shortest path between a source node and a sink node of an arbitrary distance network are developed. Different decomposition algorithms are proposed for different network topologies. Since Shier's algorithm compares very favorably with other decomposition algorithms in all the network topologies, we compare our algorithms against Shier's algorithm. It is shown that the efficiency of the proposed algorithms compares very favorably with Shier's algorithm. For special types of networks the computational requirements of the proposed algorithm is a polynomial ofO(n2).

ISSN:0028-1441    

DOI:10.1002/nav.3800300303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThis article presents another inventory model for situations in which, during the stockout period, a fractionbof the demand is backordered and the remaining fraction 1 −bis lost. By defining a time‐proportional backorder cost and a fixed penalty cost per unit lost, a unimodal objective function representing the average annual cost of operating the inventory system is obtained. The optimal operating policy variables are calculated direc

ISSN:0028-1441    

DOI:10.1002/nav.3800300304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThis article considers the production planning problem of a shop which can produce in either one shift or two shifts. Setup cost is charged whenever there is an increase in the production rate from one period to the next. Efficient planning horizon procedures have been developed for this model. A numerical example has been included to illustrate the planning horizon results.

ISSN:0028-1441    

DOI:10.1002/nav.3800300305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractAn optimality condition for the ordinary convex programming problem which utilizes the directional derivatives of the constraints is studied.

ISSN:0028-1441    

DOI:10.1002/nav.3800300306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA general result for obtaining recurrence relations between single moments of order statistics is obtained and has been used to establish the recurrence relations between moments of some doubly truncated distributions. The examples considered are Weibull, exponential, Pareto, power function, Cauchy, and logistic. Recurrence relations are also obtained for nontruncated gamma and beta distributions.

ISSN:0028-1441    

DOI:10.1002/nav.3800300307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA counterexample of general character is constructed showing that the NWUE class is not preserved under mixing. Some general classes of life distributions are introduced and their behavior under mixing and convolution is studied. These classes have a theoretical character but coincide in many cases with well‐known classes. It is proved that the DMRL class is not preserved under convolutio

ISSN:0028-1441    

DOI:10.1002/nav.3800300308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA new method for the solution of minimax and minisum location–allocation problems with Euclidean distances is suggested. The method is based on providing differentiable approximations to the objective functions. Thus, if we would like to locatemservice facilities with respect tongiven demand points, we have to minimize a nonlinear unconstrained function in the 2mvariablesx1,y1, ⃛,xm,ym. This has been done very efficiently using a quasi‐Newton method. Since both the original problems and their approximations are neither convex nor concave, the solutions attained may be only local minima. Quite surprisingly, for small problems of locating two or three service points, the global minimum was reached even when the initial position was far from the final result. In both the minisum and minimax cases, large problems of locating 10 service facilities among 100 demand points have been solved. The minima reached in these problems are only local, which is seen by having different solutions for different initial guesses. For practical purposes, one can take different initial positions and choose the final result with best values of the objective function. The likelihood of the best results obtained for these large problems to be close to the global minimum is discussed. We also discuss the possibility of extending the method to cases in which the costs are not necessarily proportional to the Euclidean distances but may be more general functions of the demand and service points coordinates. The method also can be extended easily to similar three‐dimensional p

ISSN:0028-1441    

DOI:10.1002/nav.3800300309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractIt is shown that many of the normal theory prediction intervals for statistics of random samples are still valid when the samples are correlated and have a specified covariance structure.

ISSN:0028-1441    

DOI:10.1002/nav.3800300310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA mean‐squared error comparison of smooth empirical Bayes and Bayes estimators for the Weibull and gamma scale parameters is studied based on a computer simulation. The smooth empirical Bayes estimators are determined as functions of up to 15 past estimates of the parameter of interest. Results indicate that at best the mean‐squared errors of the empirical Bayes estimators are about 20–40% larger than those of the corresponding squared‐error optimal Bayes est

ISSN:0028-1441    

DOI:10.1002/nav.3800300311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY