摘要:

AbstractWith the recent trend toward just‐in‐time deliveries and reduction of inventories, many firms are reexamining their inventory and logistics policies. Some firms have dramatically altered their inventory, production, and shipping policies with the goal of reducing costs and improving service. Part of this restructuring may involve a specific contract with a trucking company, or it may entail establishing in‐house shipping capabilities. This restructuring, however, raises new questions regarding the choice of optimal trucking capacity, shipping frequency, and inventory levels. In this study, we examine a two‐level distribution system composed of a warehouse and a retailer. We assume that demand at the retailer is random. Since the warehouse has no advance notice of the size of the retailer order, inventory must be held there as well as at the retailer. We examine inventory policies at both the warehouse and the retailer, and we explicitly consider the trucking capacity, and the frequency of deliveries from the warehouse to the retailer. Both linear and concave fixed transportation costs are examined. We find the optimal base stock policies at both locations, the optimal in‐house or contracted regular truck capacity, and the optimal review period (or, equivalently, delivery frequency). For the case of normally distributed demand we provide analytical results and numerical examples that yield insight into systems of this type. Some of our results are counterintuitive. For instance, we find some cases in which the optimal truck capacity decreases as the variability of demand increases. In other cases the truck capacity increases with variability of demand. © 1993 John Wiley

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<879::AID-NAV3220400703>3.0.CO;2-0

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

年代:1993

数据来源: WILEY

摘要:

AbstractJIT (just‐in‐time) is widely regarded as an excellent tool for reducing costs and cycle times, and for improving quality in manufacturing operations. JIT follows a multistep procedure. First, it identifies and prioritizes wastes or non‐value‐adding activities. Second, it forces these wastes to be removed. MRP (materials requirements planning) can identify the same wastes and prioritize them in the same way that JIT does, by using data from the MRP database and master production schedule, and a waste identification model. In this article, a model is developed which describes the process by which the classic JIT system identifies and prioritizes waste. An equivalent MRP waste identification model is then developed for the production environment of the classic JIT system. (The classic JIT system was developed to produce many products having low to medium volumes.) The results developed here can be extended to other production environments where adaptations of the classic JIT system are used. An example, taken from an actual application, is presented to illustrate the models and the equivalence of JIT and MRP as systems for identifying and prioritizing wastes in manufacturing. © 1993 John Wiley&S

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<905::AID-NAV3220400704>3.0.CO;2-L

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe dynamic lot‐sizing problem with learning in setups is a variation of the Wagner‐Whitin lot‐sizing problem where the setup costs are a concave, nondecreasing function of the cumulative number of setups. This problem has been a subject of some recent research. We extend the previously studied model to include nonstationary production costs and present anO(T2)algorithm to solve this problem. The worst‐case complexity of our algorithm improves the worst‐case behavior of the algorithms presently known in the literature. © 1993 John Wiley

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<925::AID-NAV3220400705>3.0.CO;2-C

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe consider the case whenncomponents are needed to assemble a given product. Components are provided by suppliers, and the period between the order time and the time a component is available (i.e., the lead time) is a random variable with a known distribution. The due date for the assembled product is also known. The costs to be taken into account are the inventory costs of the components and the backlogging cost of the assembled product. We propose an iterative algorithm which leads to the optimal order instants of the components. © 1993 John Wiley&Sons, Inc

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<933::AID-NAV3220400706>3.0.CO;2-8

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

年代:1993

数据来源: WILEY

摘要:

AbstractManufacturing and service organizations routinely face the challenge of scheduling jobs, orders, or individual customers in a schedule that optimizes either (i) anaggregate efficiencymeasure, (ii) a measure ofperformance balance, or (iii) some combination of these two objectives. We address these questions for single‐machine job scheduling systems with fixed or controllable due dates. We show that a large class of such problems can be optimized by solving either a single instance or a finite sequence of instances of the so‐called (SQC) problem, in which the sum of general quasiconvex functions of the jobs' completion times is to be minimized. To solve a single instance of (SQC), we develop an efficient, though pseudopolynomial algorithm, based on dynamic programming. The algorithm generates a solution that is optimal among all schedules whose starting time is restricted to the points of a prespecified (arbitrary) grid. The algorithm is embedded in an iterative procedure, where in each iteration a specific instance of (SQC) is solved. Special attention is given to the simultaneous minimization of the mean and variance of completion times. © 1993 John Wiley&Sons,

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<951::AID-NAV3220400707>3.0.CO;2-1

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe purpose of this article is to investigate some managerial insights related to using the all‐unit quantity discount policies under various conditions. The models developed here are general treatments that deal with four major issues: (a) one buyer or multiple buyers, (b) constant or price‐elastic demand, (c) the relationship between the supplier's production schedule or ordering policy and the buyers' ordering sizes, and (d) the supplier either purchasing or manufacturing the item. The models are developed with two objectives: the supplier's profit improvement or the supplier's increased profit share analysis. Algorithms are developed to find optimal decision policies. Our analysis provides the supplier with both the optimal all‐unit quantity discount policy and the optimal production (or ordering) strategy. Numerical examples are provided. © 1993 John Wiley&Son

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<971::AID-NAV3220400708>3.0.CO;2-T

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis article considers a two‐person game in which the first player has access to certain information that is valuable but unknown to the second player. The first player can distort the information before it is passed on to the second player. The purpose in distorting the information is to render it as useless as possible to the second player. Based on the distorted information received, the second player then maximizes some given objective. In certain cases he may still be able to use the distorted information, but sometimes the information has been so badly distorted that it becomes completely useless to him. © 1993 John Wiley&Sons, I

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<993::AID-NAV3220400709>3.0.CO;2-I

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis article defines a class of univariate functions termed composite unimodal, and shows how their minimization admits an effective search procedure, albeit one not as efficient as is Fibonacci search for unimodal functions. An approximate Lagrangian approach to an important real‐world logistics problem is seen to yield a surrogate problem whose objective function is composite unimodal. The mathematical form of this objective function is likely to be encountered in solving future real‐world problems. © 1993 John Wiley&Sons,

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<1003::AID-NAV3220400710>3.0.CO;2-D

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe consider a bivariate Pareto distribution, as a generalization of the Lindley‐Singpurwalla model, by incorporating the influence of the operating conditions on a two‐component dependent system. The properties of the model and its applications to reliability analysis are discussed. © 1993 John Wiley&Sons,

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<1013::AID-NAV3220400711>3.0.CO;2-7

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

年代:1993

数据来源: WILEY

ISSN:0894-069X    

DOI:10.1002/1520-6750(199312)40:7<1021::AID-NAV3220400712>3.0.CO;2-3

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

年代:1993

数据来源: WILEY