DYNAMIC FEEDING IN A STOCHASTIC PARALLEL PROCESSING SYSTEM

I consider a dynamic input scheduling problem of a stochastic parallel processing system consisting of n identical flexible machining cells. The processing times at each cell are independent random variables. Previous study has indicated the NP complexity of the problem. In this paper, I prove the separability under an ideal just-in-time input condition. Using the separability, I then construct an approximation procedure for most realistic applications where the separability condition is violated. The approximation procedure requires only linear time and performed quite well on an extensive test with numerical examples.     

A DYNAMIC OPTIMIZATION MODEL FOR PLANNING IN A MULTI-PRODUCT ENVIRONMENT

This paper describes an extension of the product mix problem and explicitly considers situations where demand can fluctuate over time. The additional decision variables and constraints that must be considered are described, and a revised objective function is discussed. The solution to the proposed linear programming formulation is compared to the traditional simulation and illustrates the potential for increased profits.     

DIMENSIONS OF UTILITY IN A REGIONAL PLANNING CONTEXT*

City and regional planners exist in an environment where they must satisfy numerous contending pressure groups. This paper illustrates an application of utility and decision theory in one such situation: the selection of a “land-use plan” for a large rural area in a southeastern state. The planning group was required to generate a utility matrix for a set of alternative plans consistent with their perceived hierarchy of needs for the region in question. Subsequently, expected value calculations were used to determine the optimal plan. The examination concludes with a discussion of the reliability and sensitivity of this approach, along with an exploration of areas for possible utilization and the problems attendent thereto.     

A CASE IN ON-LINE DECISION ANALYSIS FOR PRODUCT PLANNING1

This report presents an application of quantitative decision-analytic techniques to consider an opportunity for capital investment in a new product. Decision analysis is a well-established technique for evaluating major decisions in which substantial resources and time are available for the analysis and the problem is definitely formulated at the outset. This case study, however, illustrates how decision-analytic techniques can be used on-line to improve decision making in a situation in which time and resources are limited, and the manager's perception of the problem changes in response to feedback from the analysis. The basic decision problem was whether or not the AIL division of Cutler-Hammer, Incorporated should purchase a six-month option on a flight-safety system patent. The president of AIL had only a few weeks in which to make a decision. The analytic approach focused on a probabilistic discounted earnings model. This model was refined over a two-week period through a sequence of iterations which incorporated the results of both direct and indirect assessments of probabilities and values. The analysis affected the company's decision process by providing a vehicle for structuring the ongoing communication between AIL's president and his advisors, and by focusing their attention on the most important issues. In the end, the analysis facilitated a unanimous decision from the decision-making group not to purchase the option, but to consider participating in the license as a subcontractor at a later date. This strategy had not been considered at the outset.     

A MODEL OF NONBELIEF IN THE LAW OF LARGE NUMBERS

People believe that, even in very large samples, proportions of binary signals might depart significantly from the population mean. We model this “nonbelief in the Law of Large Numbers” by assuming that a person believes that proportions in any given sample might be determined by a rate different than the true rate. In prediction, a nonbeliever expects the distribution of signals will have fat tails. In inference, a nonbeliever remains uncertain and influenced by priors even after observing an arbitrarily large sample. We explore implications for beliefs and behavior in a variety of economic settings.     

REDUCING ERROR IN QUESTION AND SCALE DESIGN: A CONCEPTUAL FRAMEWORK*

The authors describe a systematic scheme for viewing the relationship between design variables and measurement error in construction of closed-end questions. Applications to teaching and research are discussed.     

EXPERIMENTAL INVESTIGATION OF PRIORITY SCHEDULING IN A BANK CHECK PROCESSING OPERATION

This paper reports on a simulation study which was undertaken to determine if float could be significantly reduced by altering a bank's check-processing priority assignments. Float, the dollar value of check payments not yet collected from parent banks, represents a significant opportunity cost in terms of lost interest income to receiving banks. The study consisted of a comparison of a major city bank's present checksorting decision rules based on minimization of check handling, versus a proposed sorting scheme based on dollar magnitudes of checks. The reults of the research indicated that float could be substantially reduced and interest income increased by employing the proposed priority of scheduting rules.     

PLANNING FOR TRUCK FLEET SIZE IN THE PRESENCE OF A COMMON-CARRIER OPTION

This paper considers a class of network optimization problems in which certain directed arcs must be covered by a set of cycles. Our study was motivated by a distribution planning problem of a commercial firm that had to make deliveries over several origin-destination pairs (directed arcs) and that could service any demand arc by using a vehicle in its own fleet or by paying a common carrier. The problem is to determine an optimal fleet size and the resulting vehicle routes while satisfying maximum route-time restrictions. We formulate the problem, describe some approximate solution strategies, and discuss important implementation issues.     

DECISION RULES IN PRODUCTION PLANNING UNDER CHANGE-CONSTRAINED SALES*

Alternative decision rules for aggregate production scheduling are specified here under chance-constrained sales and compared with the HMMS model. These rules are evaluated for their performance on the basis of simulated data on sales and it is found that the linear decision rules of the HMMS model can be considerably improved.     

AN ANALYSIS OF CAPACITY PLANNING PROCEDURES FOR A MATERIAL REQUIREMENTS PLANNING SYSTEM*

This paper is concerned with planning work-center capacity levels in manufacturing firms that employ a material requirements planning (MRP) system. It presents four procedures for developing work-center capacity plans designed to insure the production of components and assemblies as specified by the MRP plan and the master production schedule (MPS). These procedures (capacity planning using overall factors, capacity bills, resource profiles, and capacity requirements planning) are compared using simulation analysis. The results indicate that the performance of a procedure when measured against the MPS depends on the operating conditions of the manufacturing system. The results also indicate that the choice of a particular procedure often represents a compromise among the benefits of improved MPS performance, the costs of preparing and processing data, and the premium expenses required for more frequent adjustments in work-center capacity levels.     

MATERIAL PLANNING FOR A REMANUFACTURING FACILITY

This article describes the first fully integrated material planning system to facilitate the management of a remanufacturing facility. A number of firms are already engaged in this activity. They remanufacture automobile, truck, and other vehicle components, like starters, alternators, transmissions, and so forth. These firms take in used components, disassemble them, and assemble saleable products from the good parts they find. There is considerable uncertainty in the supply of used components, the good parts in those components, and the demand for remanufactured products. Our system is based on material requirements planning logic, something that many firms in the industry are already familiar with. Meetings with experts in the industry were used to set the parameters of the system and evaluate its approach.     

LARGE DEMOGRAPHIC SHOCKS AND SMALL CHANGES IN THE MARRIAGE MARKET

Between 1958 and 1961, China experienced a drastic famine. The famine substantially reduced birth rates and also adversely affected the health of these famine‐born cohorts. This paper provides nonparametric estimates of the total effects of the famine on the marital behavior of famine‐affected cohorts in rural Sichuan and Anhui. These reduced‐form estimates incorporate general equilibrium and heterogeneous treatment effects. The paper uses the Choo–Siow model to decompose observed marital outcomes into quantity and quality effects. A decline in marital attractiveness of famine‐affected cohorts, which is correlated with an increase in marital childlessness, provides support for the external validity of the Choo–Siow decomposition. The small observed changes in marriage rates of the famine‐born cohorts are due to a substantial decline in their marital attractiveness.     

A GOAL PROGRAMMING MODEL FOR OUTPUT PLANNING

This paper describes a goal programming procedure for determining satisfactory output plans for a work center. The situation being modeled is one in which work center inputs are known but vary significantly across time periods. Input levels are fixed relative to a given master production schedule, and output levels can be varied only within certain prescribed limits, at least in the short term. The similarity of the output planning problem to the more familiar aggregate planning problem is noted and discussed.     

PLANNING MAIL SURVEYS: A MANAGERIAL MODEL

Typically the market research manager faced with implementing a multiple-wave mail survey has certain requirements in terms of response rate, quality, and representativeness. The existing research literature provides some excellent insights into the effects of certain Wave 1 response stimuli. Unfortunately, very little research has been conducted on post-Wave 1 stimuli, and no research has been done on multiple-wave managerial strategy. The authors have developed a prototypic managerial planning model for evaluating various mail survey strategies over multiple-response waves. Subject Areas: Marketing Management and Marketing Research.     

A SYSTEMS PERSPECTIVE ON MATERIAL REQUIREMENTS PLANNING*

For many companies, the implementation of material requirements planning systems has failed to produce the expected improvements in manufacturing efficiency. This paper shows that MRP failure can occur in the common situation in which MRP is installed in a manufacturing environment that has evolved around manual methods of material control. A system dynamics simulation model is used to interrelate decision functions (policies) of a manufacturing firm. Simulation runs of the model operating with manual methods of material control show six- to seven-year fluctuations in production, ordering, and labor. A modified version of the model, changed only by the introduction of a requirements explosion to represent MRP, shows that MRP can actually cause more severe production fluctuations, resulting in lower average labor productivity and higher manufacturing costs. The major practical implication of the analysis is that the organizational environment that suits MRP (and utilizes its inherent strengths) is different from the environment that is likely to prevail at the time of implementation.     

A DISCRETE PRODUCTION SWITCHING RULE FOR AGGREGATE PLANNING

Aggregate planning (AP) is a necessary activity for manufacturing and services alike. A shift toward high-volume batch and continuous flow processes within American manufacturing has given rise to increasing numbers of crew-loaded facilities. A majority of AP approaches incorporate continuous decision variables and require frequent adjustments to both production and work-force settings. Despite the availability and diversity of these approaches, few significant applications have been reported. This paper presents the detailed development of a discrete AP switching rule that can be applied to a variety of cost environments. Inventory costs are estimated using an interval approach rather than traditional point estimates. The model allows incorporation of overtime options and is interactive in nature. Decision variables from the model can be disaggregated and linked directly to lower-level planning activities. Actual results of model implementation are reported. An overview of the model's incorporation into the larger context of hierarchical production planning is found in [21].     

AN EXPERIMENTAL STUDY OF THE EFFECTIVENESS OF ROLLING SCHEDULES IN PRODUCTION PLANNING

An experimental study was designed to investigate the efficiency of decisions obtained from optimizing a finite, multiperiod model and implementing (structure is parallel with “optimizing” above) those decisions on a rolling basis. The results of the study suggest that rolling schedules are quite efficient and also that they point to some important design issues in model-building for production planning.     

A CONCEPTUAL DESCRIPTION OF A FINANCIAL PLANNING MODEL FOR COMMERCIAL BANKS

This paper describes a conceptually sound and powerful model to aid bank managers in short and long range decision making for the management of the financial performance of the bank. The planning model is a key element in an integrated computer-based planning system which includes a forecast of economic, monetary, and loan market conditions, an analysis of internal relationships, and a system of reports which provide management with access to historical data and planning summaries. The planning model at the heart of the system, contains an imbedded linear programming algorithm to optimize “balance sheet management” decisions within liquidity and capital adequacy constraints. The model recognizes the interaction between assets and liabilities, it recognizes the time value of money, and it accommodates the difference between the net marginal yield for decision making, and the gross average yield used for determining revenue. Finally, the model recognizes the crucial role of liquidity with an important treatment of gross cash flows from normal asset turnover as a major source of liquidity, and the liquidity aspects of liabilities, as well as the more traditional concept of asset marketability.     

ALLOCATE: A COMPUTER MODEL FOR SALES TERRITORY PLANNING

Recent years have witnessed a renewal of interest in the application of management science techniques to personal selling related problems. Some early applications are described in [2] [7]. Cloonan has employed simulation in examination of the salesman routing problem [3] [4]. Lodish, in CALLPLAN, has devised an interactive call planning system designed to assist sales management and/or salesmen in allocating sales call time more efficiently [6]. Armstrong has devised a system he labels SCHEDULE which estimates the value of calls on accounts [1]. Hess and Samuels have designed a computer based sales districting model which is an analogue of a legislative apportionment model [5]. The objective of this paper is to explore the nature of a call planning system entitled ALLOCATE. ALLOCATE was designed to be employed by upper sales management either as an input device for sales management decisions such as sales-territory-size, or as a vehicle for determining the effects of alternative call allocation strategies on territorial revenue over multiple time periods.