bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of time‐of‐use rate periods for a utility
Authors: Dobrow Samuel A. , Lingaraj B.P. 
Published: October 2002

AbstractElectric utilities are turning to the time‐of‐use rate structure as a solution to the pricing dilemma they face. Charging relatively higher prices for peak usage and lower prices for offpeak usage provides the correct pricing signal to the consumer and promotes a more efficient utilization of the utility. Though this rate form has been successfully used in Europe for over 25 years, there has not been much experience with it in this country.An important aspect of time‐of‐use rate design is the determination of peak and offpeak hours of the day. This paper uses cluster analysis to delineate the appropriate hours for rate design. Utilities build expensive base loads plants to provide large amounts of cheap energy and less capital intensive peaking plants with high operating costs to meet short term emergency requirements leading to higher average total costs as more power is generated. The procedure presented, therefore, groups loads into rating periods such that peak periods contain large loads and offpeak periods contain low loads.The methodology is applied to the determination of time‐of‐use rating period hours for a large electric utility in the U.S. Since the optimal grouping with four seasons and three time‐of‐use periods was judged to be not feasible, a “practical best” solution was developed by modifying it appropriately. The utility set the peak hours for winter months (October to April) as 6 a.m. to 12 noon and 4 p.m. to 10 p.m. and summer (May to September) peak hours as 10 a.m. to 10 p.m., with weekends and major holidays being considered offpeak.The time‐of‐use rate structure has been implemented for commercial and industrial consumers on an experimental basis. A consumer opting for the new structure will be monitored using both structures and billed for the lower amount.
Dynamic lot sizing techniques: Survey and comparison
Authors: Zoller Klaus , Robrade Andreas 
Published: October 2002

AbstractNumerous heuristics have been proposed in the past two decades for the dynamic lot sizing problem, many of them in APICS journals. Their relative performance is explored in extensive numerical tests measuring expected costs, risks of higher than expected costs and computer time consumed. The results indicate that users of pertinent standard software systems could benefit substantially from an incorporation of more recently proposed methods, specifically Groff's (1979) stop rule and a fathoming algorithm expanding it to a look‐ahead heuristic.
Merging prescriptive and behavioral approaches for office layout
Authors: Schuler Randall S. , Ritzman Larry P. , Davis Vicki 
Published: October 2002

AbstractVarious approaches have emerged for designing office layouts and for better understanding their impact on employee attitudes and performance. They can be broadly categorized as either being prescriptive or behavioral. Prescriptive approaches are a collection of solution procedures and algorithms aimed at designing layouts around work flows and managerial preferences. While assisting with the combinatorial difficulties in layout planning, little thought is given to how individuals are influenced by spatial arrangements. The behavioral approach, on the other hand. consists of various theories and empirical studies of how spatial arrangements impact employee satisfaction and motivation. However, they pay little attention to translating such insights into workable layouts.The purposes of this paper are threefold. First, the disparate approaches to office layout are critically reviewed. Second, a new theory of spatial arrangements is proposed and tested in an exploratory fashion. Third, suggestions are made on future research and how prescriptive models can be reformulated to better handle the behavioral aspects of office layout.
Improved implementation of inventory control models through equivalent formulations
Authors: Oral Muhittin 
Published: October 2002

AbstractThis paper summarizes an actual multi‐item periodic‐review inventory control study conducted in a developing country. The firms of developing countries are usually less fortunate than their counterparts in industrialized countries in terms of management information systems, personnel and other infrastructure to successfully implement the results of research studies. Therefore, the management scientists of these countries are more obliged to formulate managerial problems in such a way that “decision‐framing” models thus developed require the least estimating and updating efforts possible, yet not sacrifice much from the optimal solution which otherwise could have been obtained. In this study, two formulations of an actualinventory control problem, one much easier and less costly to implement than the other, are shown to be equivalent with respect to the optimal solution. This result offers an instrument for implementation improvements in inventory control systems.
The effects of work‐in‐process inventory considerations on learning curve construction
Authors: Malstrom Eric M. , Fleming Jack W. 
Published: October 2002

AbstractLearning curves have been used since the 1930's as a tool to aid in the functions of cost estimating and production planning / control. While there has been much data collected to construct learning curves for airplanes, extensive coll ection of data to construct curves for electronic equipment has been limited. Further, virtually all published analyses to date have implicitly ignored the effects of work‐in‐process inventories on curve construction.This paper examines these effects through the historical construction of learning curves using actual industrial data. Work‐in‐process effects are considered through the use of linear and bilinear manufacturing progress functions. Degradation in the accuracy of curve construction is determined through the completion of a sensitivity analysis considering varying degrees of work‐in‐process activity. The results of the analysis show that work‐in‐process consideration affects the improvement curve percentage obtained. The method of work‐in‐process consideration is found to be less critical than the basic inclusion of this parameter in curve construction by one of several straightforward mathematical methods.
Managing product lines that share a common capacity base
Authors: Morecroft John D.W. 
Published: October 2002

AbstractThis paper examines the difficulties of maintaining competitive delivery times on product lines that share a common capacity base. The analysis is derived from a case study of a manufacturing firm producing finished product and service parts at a single plant. A system dynamics simulation model is used to represent production and ordering policies of the firm and its distribution network. Simulation analysis shows that these policies cause demand volatility for the finished product to be converted into supply volatility of service parts, leading to long parts delivery times and loss of service parts market share. To improve the performance of the service parts business, the production of finished product and parts should be decoupled, so the supply of the two product lines becomes independent. The results are discussed for the general multiproduct‐line case. A brief report of implementation results is included.
A heuristic algorithm for determining lot sizes of an item subject to regular and overtime production capacities
Authors: Dixon Paul S. , Elder Mark D. , Rand Graham K. , Silver Edward A. 
Published: October 2002

AbstractThe problem considered in this paper deals with the sizing and timing of replenishments for an item facing a time‐varying, but known, pattern of requirements. Regular time and overtime (the latter at a cost premium) production options are available where there are production capacities that also can vary with time. The problem is to establish the pattern of replenishments so as to keep the total of setup, carrying and overtime premium costs as low as possible without any backlogging of demand and without violating any of the capacity constraints. A heuristic procedure, simple enough to implement manually, is developed and tested on a large representative set of problems. The resulting performance is excellent, namely an average cost penalty of only 0.5%.
Optimum stock levels for excess inventory items
Authors: Tersine Richard J. , Toelle Richard A. 
Published: October 2002

AbstractInsufficient attention has been focused on the ubiquitous problem of excess inventory levels. This paper develops two models of different complexity for determining if stock levels are economically unjustifiable and, if so, for determining inventory retention levels. The models indicate how much stock should be retained for regular use and how much should be disposed of at a salvage price for a given item.The first model illustrates the basic logic of this approach. The net benefit realized by disposing of some quantity of excess inventory is depicted by the following equation:
urn:x-wiley:02726963:joom245:equation:joom245-math-0001This relationship can be depicted mathematically as a parabolic function of the time supply retained. Using conventional optimization, the following optimum solution is obtained:
urn:x-wiley:02726963:joom245:equation:joom245-math-0002where t0 is the optimum time supply retained; P is the per‐unit purchase price; Ps is the per‐unit salvage price; C is the ordering cost; Q is the usual item lot size; F is the holding cost fraction; and R is the annual demand for the item. Any items in excess of the optimum time supply should be sold at the salvage price.The second model adjusts holding cost savings, repurchase costs, and reorder costs to account for present value considerations and for inflation. The following optimum relationship is derived:
urn:x-wiley:02726963:joom245:equation:joom245-math-0003where i is the expected inflation rate and k is the required rate of return. Unfortunately this relationship cannot be solved analytically for t0; Newton's Method can be used to find a numerical solution.The solutions obtained by the two models are compared. Not surprisingly, the present value correction tends to reduce the economic time supply to be retained, since repurchase costs and reorder costs are incurred in the future while salvage revenue and holding cost savings are realized immediately. Additionally, both models are used to derive a relationship to describe the minimum economic salvage value, which is the minimum salvage price for which excess inventory should be sold.The simple model, which does not correct for time values, can be used by any organization with the sophistication level to use an EOQ. The present value model which includes an inflation correction is more complex, but can readily be used on a microcomputer. These models are appropriate for independent demand items. It is believed that these models can reduce inventory investment and improve bottom line performance.
Capacitated heuristic program for multiactivity, multi‐facility system designs
Authors: Khumawala Basheer M. , Stinson Joel P. 
Published: October 2002

AbstractMulti‐activity, multi‐facility design systems occur in a wide variety of industrial and service applications: e.g.: regional health care centers with configurations of activities at each center, and multi‐echelon inventory distribution systems. The problem in designing such systems is to determine from a candidate set of possible locations what facility locations should be opened and what types of activities should be carried out at each of the open facilities. This article presents an efficient heuristic procedure for such a problem.The heuristic procedure described can be used to solve both the uncapacitated and the capacitated problems where capacity is expressed in terms of the number of activities which can be supported by the facilities.Extensive computational experience with the heuristic is presented. The performance of the heuristic is compared against optimal solutions and the results look very encouraging.
Explaining productivity differences in North Carolina factories
Authors: Schmenner Roger W. , Cook Randall L. 
Published: October 2002

AbstractUsing detailed survey data collected from 95 large factories in North Carolina, this article examines the reasons why some factories are more productive than others. Six distinct measures of productivity are used as independent variables in the regression analyses reported. The results suggest five major themes that are shared by the most productive plants: simpler flow of materials through the process, valuing people, attending to quality, investing in hardware, and accounting for the industry's productivity growth. Several factors such as size and unionization are of no apparent importance to an explanation of cross‐factory productivity differences.
Optimal technology choice in a dynamic‐stochastic environment
Authors: Cohen Morris A. , Halperin Robert M. 
Published: October 2002

AbstractThe issue of technology management has become particularly relevant to operations planners as a result of the introduction of new, computer‐aided process technologies in recent years. At the same time, the fields of economics and management science have developed a number of models and paradigms for technology management and equipment replacement. In this article we present a model structure that builds on this theory and that is directed toward providing insights into the particular issues associated with fixed versus variable cost trade‐offs.A fairly general, dynamic, stochastic model is presented. This model links production planning with technology selection in a direct manner. The model computes optimal production plans in the face of uncertain demand in the course of evaluating the costs and benefits of each technology alternative. The key result of the article concerns conditions for the optimality of moves to lower variable cost technologies.
A simple and robust model for computing the service level impact of lot sizes in continuous and lumpy demand contexts
Authors: Etienne Eisenhower C. 
Published: October 2002

AbstractLot sizes that cover material requirements for more than two periods' demand have a built‐in service level impact. The lot sizes act as a buffer for variations in demand for every period (week) but the last. However, procedures for including the service level effect of the lot size in the lot‐sizing decision have not been developed.This article develops a very simple but robust mathematical model for computing the service level guaranteed by any lot size, Q, in both continuous and lumpy demand contexts. The model turns out to be a very simple mathematical expression involving the lot size, Q, the number of periods of demand covered by the lot size, n, and the standard deviation of the demand, σ.Some purely mathematical evaluations of the model were undertaken, and were found to predict both the direction of change of the service level as a function of Q and σ and the limit of the service level very well. A simulation experiment was also designed to test how well the model predicted the service level generated by the lot size, Q. The value of Q was set at the beginning of each experiment; the parameters of demand distribution were denned a priori. The simulations involved setting the lot size, Q, randomly generating individual demands from the known distribution, and recording the impact on the inventory and service levels.The results show that the model's prediction of the service level generated by any given lot size, Q, was very precise and reliable. The performance of the model was excellent even for cases where demand variability, as measured by the standard deviation, was high. Moreover, the built‐in service level of lot sizes turned out to be high, ranging from 95% to 100%.The ability to do a reasonably precise, a priori computation of the service level generated by a lot size, Q, has fundamental ramifications for production and materials management. One of these ramifications is the ability to size safety stocks to increase the service level from that generated by the lot size to the target sought by management. The article demonstrates that the safety stock will be smaller if the built‐in service level of the lot size is factored in. The conclusion is that lot‐sizing decisions cannot be divorced from safety stock computations, as has been done traditionally in theory and practice. Moreover, the choice of a lot‐sizing approach must consider the service level objectives of the company.
An experimental investigation of FMS scheduling rules under uncertainty
Authors: Denzler David R. , Boe Warren J. , Duplaga Edward 
Published: October 2002

AbstractThis article reports the results of an experimental investigation of scheduling decision rules for a dedicated flexible manufacturing system (FMS) with variable performance times and machine break‐downs. An existing FMS was modeled using the actual performance times obtained from the system's transaction log. The performance of six heuristic scheduling rules were tested under differing uncertainty conditions.The simulation model included three types of uncertainty, namely: minor breakdowns, which averaged two hours and occurred once every two shifts; major breakdowns, which averaged ten hours and occurred once every ten shifts; and operation time deviations, which ranged from 0% to 20% of standard time. The runtime for the simulation approximated the work to be done over a ten‐week period of time, or 7,590 parts.Six different part loading rules were used to determine whether they could produce different performance results. The smallest proportion of jobs launched and the next empty pallet rule worked appreciably better than the rest of the rules in obtaining the highest FMS utilization.
The operations management research agenda: An update
Authors: Amoako‐Gyampah Kwasi , Meredith Jack R. 
Published: October 2002

AbstractAn agenda for operations management (OM) research was first proposed by Miller et al. in 1981. However, until Hill et al. examined recent Ph.D. dissertations in 1987, no other work on the agenda had been done. We take another look at the status of the OM research agenda from a slightly different perspective. The state of OM research in the United States is examined through a survey of published journal articles by OM researchers in the period 1982–1987. Overall, 362 journal articles were reviewed and classified into 17 categories.The topical areas of technology and innovation, service operations, productivity, and manufacturing strategy suggested in the OM agenda for future research are now receiving some attention from OM researchers. We also compared our findings to the results of Chase's 1980 study and notice that, though statistically, OM research has changed since the time of Chase's study, the overall emphasis and orientation still appear to be the same.To account for the publication time lag suffered by most journal articles, we also examined papers from the Decision Sciences Institute (DSI) proceedings for 1986 and 1987. The DSI proceedings were used as a surrogate measure of pipeline research. Statistically, the DSI proceedings appear to be different from contemporary OM research as published in the journals; the directions of the pipeline papers are more in agreement with the directions suggested in the OM agenda.The final part of this study examined the types of research approaches used in the journal publications and compared them to those used in the DSI proceedings. There was no statistically significant difference between the research approaches used in the published and pipeline research. Our conclusion is that, though the OM agenda had suggested broadening the research strategies used in studying OM issues, the dominant strategies continue to be model and laboratory (primarily simulation) based.
A multivariate approach for assessing facility layout complexity
Authors: Makens Paul K. , Rossin Donald E , Springer Mark C. 
Published: October 2002

AbstractThe block layout problem is concerned with locating activities or departments of an organization such that those activities with the strongest interrelationships are closest to each other. Many solution procedures have been proposed for this problem. Research indicates that certain solution procedures perform reasonably well on certain data sets, but yield less desirable results on other problem sets with no clearly superior procedure emerging. Attention has focused on the complexity of the problem as the deciding factor. The measure of complexity most commonly used is the coefficient of variation of the problem data. As the coefficient of variation increases, it is suggested that human planners might be better able to handle the problem. The research in this area indicates mixed results.It is argued in this paper that these measures are overly simplistic and cannot fully capture all of the aspects which determine problem complexity. A multivariate approach for measuring problem complexity is proposed. This approach is based upon the inherent structure of the problem itself. It is thus based on structural pattern recognition. An algorithm for determining the basic substructures and megastructure of a problem is proposed. Differences in performance of different solution procedures on different layout problems are examined using this multivariate approach. The approach is illustrated with example problems from the literature. An unpublished problem from a company is used to illustrate the utility of the megastructure as a guide for laying out a facility.
Load smoothing by the planning and order review/release systems: A simulation experiment
Authors: Melnyk Steven A. , Ragatz Gary L. , Fredendall Lawrence 
Published: October 2002

AbstractMost research studies investigating the impact of Order Review/Release (ORR) mechanisms on shop performance have focused strictly on managing the flow of orders to the shop floor once they have been generated by the planning system. This approach ignores the possibility that the manufacturing planning system may be managing the incoming work flow so that peaks and valleys in the work load have been smoothed out.This study shows, via a simple computer simulation of a random job shop, that such smoothing by the planning system can improve system performance and enhance the effects of Order Review/Release. The two ‘filtering’ mechanisms of planning system smoothing and Order Review/Release have a complementary impact on the system, with smoothing working to reduce flow time and flow time variability and ORR working to reduce work in process and work in process variability. The combination of smoothing with ORR results in shorter and more consistent lead times, lower and more stable work‐in‐process levels and better delivery performance. This results in a system which is very stable and predictable.Further, the study shows that the combined effects of smoothing and ORR can improve the performance of simple shop floor dispatching rules like first come‐first served to the point where they are competitive with more sophisticated, due date oriented rules. This raises the possibility of simplifying control mechanisms on the shop floor by doing a better job of work load planning and order release.