摘要:

AbstractShip berthing plans reserve a location for inbound U.S. Navy surface vessels prior to their port entrance, or reassign ships once in port to allow them to complete, in a timely manner, reprovisioning, repair, maintenance, training, and certification tests prior to redeploying for future operational commitments. Each ship requires different services when in port, such as shore power, crane, ordnance, and fuel. Unfortunately, not all services are offered at all piers, and berth shifting is disruptive and expensive: A port operations scheduler strives to reduce unnecessary berth shifts. We present an optimization model for berth planning and demonstrate it for Norfolk Naval Station, which exhibits all the richness of berthing problems the Navy faces. ® 1994 John Wiley&Sons, Inc

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<1::AID-NAV3220410102>3.0.CO;2-L

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis article examines the problem of simultaneously assigning a common due date to a set of independent jobs and scheduling them on identical parallel machines in such a way that the costs associated with the due date and with the earliness or tardiness of the jobs are minimized. We establish that, for certain values of the due‐date cost, an optimal schedule for this problem is also optimal for an early/tardy scheduling problem studied by Emmons. We discuss the solution properties for the two problems, and show that both problems are NP‐hard even for two machines. We further show that these problems become strongly NP‐hard if the number of machines is allowed to be arbitrary. We provide a dynamic programming solution for the problems, the complexity of which indicates that the problems can be solved in pseudopolynomial time as long as the number of machines remains fixed. Finally, we present the results of a limited computational study. © 1994 John Wiley&Son

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<17::AID-NAV3220410103>3.0.CO;2-X

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

年代:1994

数据来源: WILEY

摘要:

AbstractGiven a set of jobs, a processing time and a weight for each job, several parallel and identical machines, and a common due date that is not too early to constrain the scheduling decision, we want to find an optimal job schedule so as to minimize the maximum weighted absolute lateness. We show that this problem is NP‐complete even for the single‐machine case, and is strongly NP‐complete for the general case. We present a polynomial time heuristic for this problem and analyze its worst‐case performance. Empirical testing of the heuristic is reported, and the results suggest that the performance is asymptotically optimal as the number of jobs tends to infinity. © 1994 John Wiley&S

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<33::AID-NAV3220410104>3.0.CO;2-S

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn this article we apply perturbation analysis (PA), combined with conditional Monte Carlo, to obtain derivative estimators of the expected cost per period with respect tosandS, for a class of periodic review (s, S) inventory systems with full backlogging, linear holding and shortage costs, and where thearrivalsof demands follow a renewal process. We first develop the general form offourdifferent estimators of the gradient for the finite‐horizon case, and prove that they are unbiased. We next consider the problem of implementing our estimators, and develop efficient methodologies for the infinite‐horizon case. For the case of exponentially distributed demand interarrival times, we implement our estimators using asinglesample path. Generally distributed interarrival times are modeled as phase‐type distributions, and the implementation of this more general case requires a number of additional off‐line simulations. The resulting estimators are still efficient and practical, provided that the number of phases is not too large. We conclude by reporting the results of simulation experiments. The results provide further validity of our methodology and also indicate that our estimators have very low variance. © 1994 John Wiley&S

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<47::AID-NAV3220410105>3.0.CO;2-I

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

年代:1994

数据来源: WILEY

摘要:

AbstractA retailer or distributor of finished goods, or the manager of a spare‐parts inventory system, must generally forecast the major portion of demand. A specific customer‐service levelp(fraction of replenishment intervals with no stockout) implies two challenges: achieve the service within a small interval plus or minus, and do so with a minimum‐cost investment in inventory. Thepth fractile of lead‐time demand (LTD) is the reorder point (ROP) for this service measure, and is often approximated by that fractile of a normal distribution. With this procedure, it is easy to set safety stocks for an (s, Q) inventory system. However, Bookbinder and Lordahl [2] and others have identified cases where the normal approximation yields excessive costs and/or lower service than desired. This article employs anorder‐statisticapproach. Using available LTD data, the ROP is simply estimated from one or two of the larger values in the sample. This approach is sufficiently automatic and intuitive for routine implementation in industry, yet is distribution free. The order‐statistic method requires only a small amount of LTD data, and makes no assumptions on the form of the underlying LTD distribution, nor even its parameters μ and ρ. We compare the order‐statistic approach and the normal approximation, first in terms of customer service and then using a model of expected annual cost. Based upon characteristics of the available LTD data, we suggest a procedure to aid a practitioner in choosine between the normal and order‐statistic method. © 1994 Jo

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<81::AID-NAV3220410106>3.0.CO;2-9

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

年代:1994

数据来源: WILEY

摘要:

AbstractDemand for some items can depend on the inventory level on display, a phenomenon often exploited by marketing researchers and practitioners. The implications of this phenomenon have received scant attention in the context of periodic‐review inventory control models. We develop an approach to model periodic‐review production/inventory problems where the demand in any period depends randomly, in a very general form, on the starting inventory level. We first obtain a complete analytical solution for a single‐period model. We then investigate two multiperiod models, one with lost sales and the other with backlogging, whose optimal policies turn out to be myopic. Some extensions are also discussed. © 1994 John Wiley&Son

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<99::AID-NAV3220410107>3.0.CO;2-W

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

年代:1994

数据来源: WILEY

摘要:

AbstractFor infinite‐horizon replacement economy problems it is common practice to truncate the problem at some finite horizon. We develop bounds on the error due to such a truncation. These bounds differ from previous results in that they include both revenues and costs. Bounds are illustrated through a numerical example from a real case in vehicle replacement. © 1994 John Wiley&Sons, I

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<117::AID-NAV3220410108>3.0.CO;2-U

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

年代:1994

数据来源: WILEY

摘要:

AbstractWe present an inventory model where the supply becomes randomly unavailable for random periods of time. We investigate the operating characteristics of the model, and we study the robustness of the optimal order quantity. Our work builds on Parlar and Berkin [2]. © 1994 John Wiley&Sons. Inc

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<129::AID-NAV3220410109>3.0.CO;2-M

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

年代:1994

数据来源: WILEY

摘要:

AbstractOne of the diagrammatic methods for solving two‐person 2 ×nmatrix games can be extended to solvem×ngames where each column of the matrix is a concave function of the row number. This gives a simple proof of a theorem of Benjamin and Goldman that such games have solutions involving no more than two consecutive strategies for the row player, and no more than two strategies for the column player. Two extensions are discussed. © 1994 John Wiley&Sons,

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<133::AID-NAV3220410110>3.0.CO;2-E

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

年代:1994

数据来源: WILEY

ISSN:0894-069X    

DOI:10.1002/1520-6750(199402)41:1<::AID-NAV3220410101>3.0.CO;2-C

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

年代:1994

数据来源: WILEY