A Model for Master Production Scheduling in Uncertain Environments

In uncertain environments, the master production schedule (MPS) is usually developed using a rolling schedule. When utilizing a rolling schedule, the MPS is replanned periodically and a portion of the MPS is frozen in each planning cycle. The cost performance of a rolling schedule depends on three decisions: the choice of the replanning interval (R), which determines how often the MPS should be replanned; the choice of the frozen interval (F), which determines how many periods the MPS should be frozen in each planning cycle; and the choice of the forecast window (T), which is the time interval over which the MPS is determined using newly updated forecast data. This paper uses an analytical approach to study the master production scheduling process in uncertain environments without capacity constraints, where the MPS is developed using a rolling schedule. It focuses on the choices of F, R, and T for the MPS. A conceptual framework that includes all important MPS time intervals is described. The effects of F, R, and T on system costs, which include the forecast error, MPS change, setup, and inventory holding costs, are also explored. Finally, a mathematical model for the MPS is presented. This model approximates the average system cost as a function of F, R, T, and several environmental factors. It can be used to estimate the associated system costs for any combination of F, R, and T.     

论我国会计国际化的选择模式

在对中国会计国际化的现状和趋势做出评析的基础上,通过在会计环境、会计规范体系、会计目标、财务报告等方面对我国及美国、加拿大、英国、德国、法国等国家的会计模式进行比较,提出了我国的会计国际化在技术层面上应加快国际化的进程,而在规范体系尤其是法律规范方面要加强我国的国家特色。当前我国会计国际化速度正在加快,在会计国际化过程中,可在国际会计准则的基础上,吸收各国行之有效的会计惯例和做法,如加拿大及欧洲诸国对环境会计报告的要求和做法;在会计教育方面,应大量借鉴英语国家会计教育的有益经验。但我国政府主导型的准则制定模式应予以坚持。     

Optimal Purchase and Transportation Cost Lot Sizing for a Single Item

A review of the literature indicates that the traditional approach for evaluating quantity discount offerings for purchased items has not adequately considered the effect that transportation costs may have on the optimal order quantity; despite the general fact that purchased materials must bear transportation charges. The transportation cost structure for less-than-truckload (LTL) shipments reflects sizable reductions in freight rates when the shipment size exceeds one of the nominal rate breakpoints. However, the shipper must also be aware of the opportunity to reduce total freight costs by artificially inflating the actual shipping weight to the next rate breakpoint, in order that a lower marginal tariff is achieved for the entire shipment. Such over-declared shipments result in an effective freight rate schedule that is characterized by constant fixed charge segments in addition to the nominal marginal rates. Over-declared shipments are economical when the shipment volume is less than the rate breakpoint, but greater than a cost indifference point between the two adjacent marginal rates. This paper presents a simple analytical procedure for finding the order quantity that minimizes total purchase costs which reflect both transportation economies and quantity discounts. After first solving for the series of indifference points that apply to a particular freight rate schedule, a total purchase cost expression is presented that properly accounts for the actual transportation cost structure. The optimal purchase order quantity will be one of the four following possibilities: (1) the valid economic order quantity (EOQ), QC; (2) a purchase price breakpoint in excess of QC; (3) a transportation rate breakpoint in excess of QC; and (4) a modified EOQ which provides an over-declared shipment in excess of QC. Finally, an algorithm which systematically explores these four possibilities is presented and illustrated with a numerical example.     

Partitioning Work Centers for Group Technology: Insights from an Analytical Model*

This paper develops analytical approximations based on an M/M/c queuing model, for the operating characteristics of job shop work centers. The model is used to analyze the effects of partitioning a work center and introducing setup reduction into the cell components. The results using this model are shown to be consistent with the results of prior simulation-based studies of group technology under certain parameter ranges. A simulation experiment was conducted to verify the effects with multi-item, non-Markovian assumptions, and the general effects predicted by the model were found to apply.     

Integrating the Content and Process of Strategic MIS Planning with Competitive Strategy*

This paper presents a framework that links strategic MIS planning and business strategy and relates it to competitive advantage and company performance. To achieve this objective, the paper first delineates the dimensions of strategic MIS planning, focusing on both content and process issues. The notion of fit within dimensions, between sets of dimensions (process and content), and between MIS planning and competitive strategy is also introduced. Next, employing the Miles-Snow typology of business strategy, the paper posits normative differences in the dimensions of strategic MIS planning along different business (or competitive) strategies. The implications of our study for both decision makers and scholars are discussed. Propositions that tie competitive strategy, strategic MIS planning, and company financial performance are then presented. The paper concludes by providing direction for future research.     

Tandem Configuration Automated Guided Vehicle Systems: A Comparative Study*

Automated guided vehicle (AGV) systems provide the flexibility and integration required for flexible manufacturing systems. Previous AGV system studies have attempted to reduce the controlling complexities commonly encountered in these systems. However, this has not been accomplished without additional resources (e.g., automated guided vehicles) and lower system flexibility. The primary objective of this study is to compare the performance of AGV system configurations that reduce controlling and modification complexities (i.e., tandem configurations) to traditional AGV system configuration. Three AGV system configurations were tested under 16 experimental conditions. Performance metrics considered were AGV utilization, mean flowtime, mean tardiness, and percent tardy. The results of this study extend the findings of the previous studies in demonstrating the viability of tandem configurations, in that the tandem configurations match the performance of traditional configuration across all performance metrics, without sacrificing ease of control and system flexibility. Finally, the cost tradeoffs inherent in selecting a particular configuration are discussed.     

Development and Validation of TQM Implementation Constructs

The contemporary quality management (QM) literature prescribes various quality improvement strategies. However, it lacks scientifically developed and tested constructs that represent an integrative QM philosophy. Moreover, an impact of the prescribed QM strategies on a firm's product quality has not been analyzed. Through a detailed analysis of the literature, this research identifies 12 constructs of integrated QM strategies. Using a survey of 371 manufacturing firms, the constructs are then empirically tested and validated. LISREL 7 is used for this purpose. Finally, a framework to examine the effects of integrated QM strategies on a firm's product quality is suggested. Comparisons between this and two other comprehensive scales of TQM are made.     

会计模糊性原因分析及治理对策

由于模糊论、契约论、社会经济环境、人类认识的局限性、会计本身等因素的影响,会计信息具有一定的模糊性。为提高会计信息的有用性,应从加强模糊会计理论研究、完善会计准则、重视充分披露原则、强化模糊概念和模糊方法在会计中的应用、对会计信息进行过滤处理。这对于我国加强会计模糊研究、完善会计准则、提高会计信息的质量具有一定的参考价值。     

On Extending Russell and Krajewski's Algorithm for Economic Purchase Order Quantities*

Russell and Krajewski presented an optimal purchase order quantity algorithm that considered the effect of the transportation rate structure for less-than-truckload (LTL) shipments. The authors applied the Russell and Krajewski algorithm to a variety of freight classes and lengths-of-haul. Anomalous cases were found in which the freight rate schedule, when used with the suggested algorithm, resulted in incorrect order size decisions. In this comment, the authors consider the impact of these anomalies on the optimal order quantity and associated total costs. A procedure is presented to adjust the Russell and Krajewski algorithm to arrive at the optimal purchase order quantity and the lowest total annual cost.     

User Perceptions of Decision Support Effectiveness: Two Production Planning Experiments*

Decision support systems continue to be very popular in business, despite mixed research evidence as to their effectiveness. We hypothesize that what-if analysis, a prominent feature of most decision support systems, creates an “illusion of control” causing users to overestimate its effectiveness. Two experiments involving a production planning task are reported which examine decision makers' perceptions of the effectiveness of what-if analysis relative to the alternatives of unaided decision making, and quantitative decision rules. Experiment 1 found that almost all subjects believed what-if analysis was superior to unaided decision making, although using what-if analysis had no significant effect on performance. Experiment 2 found that decision makers were indifferent between what-if analysis and a quantitative decision rule which, if used, would have led to significant cost savings. Thus, what-if analysis did create an illusion of control: decision makers perceived performance differences where none existed, and did not detect large differences when they were present. In both experiments, decision makers exhibited difficulty realizing that their positive beliefs about what-if analysis were exaggerated. Such misjudgments could lead people to continue using what-if analysis even when it is not beneficial and to avoid potentially superior decision support technologies.