摘要:

AbstractOrienteering is a sport in which start and end points are specified along with other locations. These other locations have associated scores. Competitors seek to visit, in a fixed amount of time, a subset of these locations on the way from the start point to the end point in order to maximize the total score. An effective center‐of‐gravity heuristic is presented that outperforms heuristics from the literat

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<307::AID-NAV3220340302>3.0.CO;2-D

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn most of the stochastic resource‐allocation problems discussed in the literature it is supposed that the key resource, herein called the machine, is continuously available until all tasks are completed. Plainly, this will often be an unrealistic assumption. This paper supposes that intermittent availability of the machine is due to a breakdown proces, and describes various approaches to the evaluation of the effect of breakdowns. Firstly, for the case of geometric up times, conditions are given under which breakdowns have no effect on optimal allocation strategies. Secondly, two different procedures are given which yield an upper bound on the loss incurred when a processing strategy is adopted under the assumption of no breakdowns, when in fact breakdowns do occur. The first of these is based on Gittins's indices and is described for the case of geometric up times, and the second uses a bounding argument on the breakdown proces

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<319::AID-NAV3220340303>3.0.CO;2-5

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

年代:1987

数据来源: WILEY

摘要:

AbstractIt is desired to select numbers of area and point interceptors that minimize the cost of such defensive missiles under the condition that the maximum total expected damage produced by an unknown number of attacking missilesAbe bounded above by a given function ofA. Area coverages may overlap. The attacker is assumed to know the numbers of area and point interceptors and to launch a simultaneous attack (of arbitrary sizeA) against all targets, which is optimal against the given defenses. The defender is assumed to observe the attack and then allocate his area and point interceptors against attacking missiles so as to minimize the total expected damage. Upper and lower bounds on the minimal cost are obtained by solving integer programming problems.

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<337::AID-NAV3220340304>3.0.CO;2-Z

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn this article we have generalized previous models on multiechelon recoverable inventory systems to cover the cases of batch ordering and shipment policy, and when items can either be repaired or condemned. The batch ordering and shipment policy is appropriate when the setup cost for shipment and order and/or the demand rates of the items are relatively high. The operating characteristics of such a system have been studied. Specifically, the probability distribution of backorder levels at the bases are analyzed for different repair‐time distributions. An approximation scheme is proposed for this distribution, and is evaluated using extensive simulation results. The results indicate that the scheme is very effective in providing near‐optimal stocking levels in such a sys

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<365::AID-NAV3220340305>3.0.CO;2-P

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

年代:1987

数据来源: WILEY

摘要:

AbstractA system of two parallel queues where the arrivals from a single stream of customers join the shorter queue is considered. Arrivals form a homogeneous Poisson stream and the service times in each of the two queues are independent exponential variates. By treating one of the queues as bounded, the steady‐state probability vector for the system can be expressed in a modified matrix‐geometric form and can be computed efficiently. Computational procedures for the sojourn time distribution and characteristics of the departure stream are developed. Some numerical results are presented, and based on these results an efficient approximation scheme for the model is developed which can be readily extended to systems with more than two parallel que

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<381::AID-NAV3220340306>3.0.CO;2-K

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper is concerned with a modification of a recently proposed variant of Karmarkar's algorithm for solving linear programming problems. In analyzing this variant, we exhibit interesting and useful relationships of these types of algorithms with barrier function methods, and subgradient optimization procedures involving space dilation techniques, which subsume the well‐known ellipsoidal type of algorithms. Convergence of this variant is established under certain regularity conditions. We also provide remarks on how to obtain dual variables or Lagrange multipliers at optimalit

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<399::AID-NAV3220340307>3.0.CO;2-6

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

年代:1987

数据来源: WILEY

摘要:

AbstractReliability control for mission‐critical items is studied. The purpose of the control is to ensure the attainment during mission time of a required performance level which is based on suitably defined measures. This is achieved by replacing the item during normal operation time as soon as the reliability requirement is violated. We first consider the case of a known life distribution, but the main focus of the work is on the case where the life distribution is not completely specified. A Bayesian approach is taken and a replacement procedure is constructed on the basis of the overall uncertainty we face, namely, the stochastic failure process and our (continuously revised) probabilistic assessment of the underlying life distribution. The resulting replacement policy is investigated and detailed results are obtained for some common life distribution

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<417::AID-NAV3220340308>3.0.CO;2-S

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

年代:1987

数据来源: WILEY

摘要:

AbstractEfficient computation of tight bounds is of primary concern in any branch‐and‐bound procedure for solving integer programming problems. Many successful branch‐and‐bound approaches use the linear programming relaxation for bounding purposes. Significant interest has been reported in Lagrangian and surrogate duals as alternative sources of bounds. The existence of efficient techniques such as subgradient search for solving Lagrangian duals has led to some very successful applications of Lagrangian duality in solving specially structured problems. While surrogate duals have been theoretically shown to provide stronger bounds, the difficulty of surrogate dual‐multiplier search has discouraged their employment in solving integer programs. Based on the development of a new relationship between surrogate and Lagrangian duality, we suggest a new strategy for computing surrogate dual values. The proposed approach allows us to directly use established Lagrangian search methods for exploring surrogate dual multipliers. Computational experience with randomly generated capital budgeting problems validates the economic feasibility of the propo

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<431::AID-NAV3220340309>3.0.CO;2-P

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper applies the well‐known reflection principle for random walks to the analysis of the transientM/M/1 queueing system. A closed‐form solution is obtained for the probability that exactlyiarrivals andjdepartures occur over an interval of lengthtin anM/M/1 queueing system that containsnusers at the beginning of the interval. The derivation of this probability is based on the calculation of the number of paths between two points in a two‐dimensional−ycoordinate system that lie above thexaxis and touch thexaxis exactlyrtimes. This calculation is readily performed through the application of the reflection pr

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<451::AID-NAV3220340310>3.0.CO;2-8

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

年代:1987

数据来源: WILEY

ISSN:0894-069X    

DOI:10.1002/1520-6750(198706)34:3<::AID-NAV3220340301>3.0.CO;2-H

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

年代:1987

数据来源: WILEY