摘要:

AbstractIn this article we consider a multiproduct dynamic lot‐sizing model. In addition to a separate setup cost for each product ordered, a joint setup cost is incurred when at least one product is ordered. We formulate the model as a concave minimization problem over a compact polyhedral set and present a finite branch and bound algorithm for finding an optimal ordering schedule. Superiority of the branch and bound algorithm to the existing exact procedures is demonstrated. We report computational experience with problems whose dimensions render the existing procedures computationally infeasibl

ISSN:0894-069X    

DOI:10.1002/nav.3220350102

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

年代:1988

数据来源: WILEY

摘要:

AbstractTheM/G/1 queue with single and multiple server vacations is studied under both the preemptive and non‐preemptive priority regimes. A unified methodology is developed to derive the Laplace‐Stieltjes transform and first two moments of the waiting timeWkof a class‐kcustomer for each of the four models analyzed. The results are given a probabilistic representation involving mean residual life

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<23::AID-NAV3220350103>3.0.CO;2-B

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn this article our objective is to evaluate the performance of a WSPT (weighted shortest processing time) rule for schedulingnindependent jobs where the resources to process these jobs vary over time and a job can be processed by several processors simultaneously. This problem was raised by Baker and Nuttle [2]. A linear‐programming (LP) model is formulated to obtain a lower bound on the minimum value of the weighted completion times. The purpose of the model is to provide a basis for evaluating the WSPT heuristic. 1000 experiments were performed using different resource profiles to test the performance of WSPT. Using WSPT, the weighted completion times were found to be, on the average, 0.2% away from their LP lower bound

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<35::AID-NAV3220350104>3.0.CO;2-3

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn this article we model a two‐echelon (two levels of repair, one level of supply) repairable‐item inventory system using continuous‐time Markov processes. We analyze two models. In the first model we assume a system with a single base. In the second model we expand this model to includenbases. The Markov approach gives rise to multidimensional state spaces that are large even for relatively small problems. Because of this, we utilize aggregate/disaggregate techniques to develop a solution algorithm for finding the steady‐state distribution. This algorithm is exact for the single‐base model and is an approximation for then‐base model, in which case it is found to be very accurate and computationally ver

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<49::AID-NAV3220350105>3.0.CO;2-U

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe following experiment is considered.nunits are tested simultaneously until either therth failure occurs or a fixed timetois reached. In the first part of the manuscript, the failure times are assumed to be i.i.d. exponential with an unknown scale parameter 1/λ. The second part deals with the modification where failed units are replaced. In the third part, extensions to nonexponential failure times are outlined. Givenrandto, the goal is to minimize the expected cost as a function ofn.Hereby, the cost is defined through three componentsc1,c2, andc3, respectively, which are associated with (1) the time length of the experiment, (2) the numbernof units tested, and (3) some fixed overall cost of the experiment, respectively

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<63::AID-NAV3220350106>3.0.CO;2-R

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn this article we present a methodology for postoptimality and sensitivity analysis of zero‐one goal programs based on the set ofk‐best solutions. A method for generating the set ofk‐best solutions using a branch and bound algorithm and an implicit enumeration scheme for multiple objective problem are discussed. Rules for determining the range of parameter changes that still allows a member of thek‐best set to be optimal are developed. An investigation of a sufficient condition for postoptimality analysis is also pr

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<73::AID-NAV3220350107>3.0.CO;2-L

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn this article we develop a class of general knapsack problems which are hard for branch and bound algorithms. The number of alternate optimal solutions for these problems grows exponentially with problem parameters. In addition the LP bound is shown to be ineffective. Computational tests indicate that these problems are truly difficult for even very small problems. Implications for the testing of algorithms using randomly generated problems is discussed.

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<85::AID-NAV3220350108>3.0.CO;2-D

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn this article we consider block replacement policies where the operating item is replaced by a new one at timeskT, k= 1, 2, …, independently of its failure history. At failure the item is either replaced by a new or a used one or remains inactive until the next planned replacement. The mathematical model is defined and general analytical results are obtained. Computations are carried out for the case where the underlying life distribution is gamma or Weibul

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<99::AID-NAV3220350109>3.0.CO;2-3

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis article deals with the solution of convex quadratic programs by iteratively solving a master problem and a subproblem as proposed previously by Sacher. The approach has the advantage that the subproblems are linear programs so that advantage can be taken of existing schemes for solving large linear problems. At each step in solving the master problem, a closed‐form solution can be specified so that the procedure is well suited for solving large quadratic programs and can take advantage of the constraint structur

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<111::AID-NAV3220350110>3.0.CO;2-#

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe study the (s,S) inventory system in which the server takes a rest when the level of the inventory is zero. The demands are assumed to occur for one unit at a time. The interoccurrence times between successive demands, the lead times, and the rest times are assumed to follow general distributions which are mutually independent. Using renewal and convolution techniques we obtain the state transition probabilities.

ISSN:0894-069X    

DOI:10.1002/1520-6750(198802)35:1<119::AID-NAV3220350111>3.0.CO;2-P

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

年代:1988

数据来源: WILEY