Master production scheduling,customer service and manufacturing flexibility in an assemble-to-order environment

A key element of manufacturing planning and control involves the inter-functional coordination of various manufacturing requirements. This paper reports the results of a simulation experiment that compares alternative master production scheduling (MPS) procedures in an assemble-to-order environment. The MPS procedures are superbills and covering sets. For a given investment in safety stocks the managerial problem is how to construct the MPS in order to minimize the firm's delivery time pressures. The results of the simulation experiment strongly support the use of the superbill techniques over the covering set technique. Moreover, of the experimental factors that influence delivery time performance, the choice of master production scheduling technique has the largest effect. Demand variability has the next greatest effect on delivery time performance. The safely stock level has the third greatest effect and product commonality was fourth. Finally, the managerial implications of the results are discussed in detail.     

Time- and cost-based priorities for job shop scheduling

Competitively, cost- and time-based scheduling should provide a firm with a powerful market advantage. The cost- and time-based priority scheduling concept is driven by profit maximization and quick response in a competitive market. The literature on shop scheduling contains numerous studies reporting on the use of dispatching rules that are based only on the time criterion. Alternatively there have been only a few published articles that specifically consider a composite of cost and time. Aggarwal and McCarl and Scudder and Hoffmann have investigated the use of cost and time information for determining the job priority in random job shops. One result of this study is a reconciliation of the differences between the Aggarwal and McCarl and the Scudder and Hoffmann study. Moreover, a simplistic priority rule based on profit margin and due dates is introduced and tested. The results reported in this research are an attempt to reconcile the issue of time-based versus cost-based priority rule performance.     

Quantity discount decisions under conditions of multiple items,multiple suppliers and resource limitations

This research considers quantity discount procedures under conditions of multiple items, resource limitations and multiple suppliers. This is a very complex problem that has not yet been addressed in the literature. In this paper we offer an efficient heuristic programming procedure for evaluating alternative discount schedules. Moreover we use an example problem to test the suggested procedure. The results offer several encouraging findings for managers facing this impressive problem.     

Back to Basics: Maisons Jaoul and the Art of the mal foutu

Although Le Corbusier's debt to vernacular architecture has been frequently discussed, the particular effects that the architect searched for in his postwar buildings have been insufficiently studied. The Maisons Jaoul (1951–1955) are a case in point. Le Corbusier's search for a direct, expressive, and tactile quality of building is here also related to his interest in the ideas and practice of Jean Dubuffet. Le Corbusier was not a regionalist but he particularly admired craftsmen from the Mediterranean basin, who, he believed, retained a vigorous and comprehensive sympathy for materials. This article, using firsthand interviews with Le Corbusier's craftsmen, explores the complex and subtle ways that Le Corbusier and his assistants negotiated the textural effects they desired, which Le Corbusier described ironically as mal foutu (messed up).     

TWO TESTS OF A THEORY OF VERBAL-DISCRIMINATION LEARNING.

2 TESTS WERE MADE OF A THEORY WHICH ASSUMES THAT VERBAL-DISCRIMINATION (VD) LEARNING IS BASED UPON A FREQUENCY DIFFERENTIAL BETWEEN THE RIGHT AND WRONG WORDS. IN EXP. I 150 UNDERGRADUATES WERE GIVEN EITHER 0, 2, OR 5 FREE-RECALL LEARNING (FL) TRIALS ON A LIST OF WORDS PRIOR TO THE WORDS' BECOMING EITHER THE CORRECT OR INCORRECT MEMBERS OF PAIRS IN A VD LIST. WHEN WORDS FROM FL WERE CORRECT IN VD, PERFORMANCE ON VD LEARNING WAS NEARLY PERFECT ON ALL TRIALS. WHEN WORDS FROM FL BECAME INCORRECT IN VD LEARNING, 2 FL TRIALS HAD ESSENTIALLY NO INFLUENCE ON VD LEARNING; WITH 5 FL TRIALS PERFORMANCE WAS INITIALLY HIGH ON VD LEARNING, BUT PROGRESSED VERY SLOWLY OVER TRIALS. IN EXP. II 45 SS WERE FORCED TO VOICE BOTH THE CORRECT AND INCORRECT MEMBERS OF PAIRS IN A VD LIST. THE INTENT WAS TO MAKE LEARNING BASED ON A FREQUENCY DIFFERENTIAL DIFFICULT. LEARNING WAS MARKEDLY RETARDED AS COMPARED WITH CONTROLS. CONTROLS FORCED TO PRONOUNCE ONLY THE CORRECT RESPONSE PERFORMED BETTER THAN A GROUP LEFT TO THEIR OWN DEVICES. BOTH EXPERIMENTS ARE INTERPRETED AS SUPPORTING THE THEORY. (FRENCH SUMMARY) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple price breaks and alternative purchase lot-sizing procedures in material requirements planning systems

The paper reports the results of several simulation experiments that compare alternative procedures for determining purchase quantities in MRP systems when multiple discounts are available. The procedures are the modified least unit cost (LUCm), the modified MeLaren's order moment (MOMm) and a ‘traditional’ procedure (DOQ) that is commonly used when evaluating quantity discounts. For this work, three purchased parts with two levels of discount attractiveness, two price break offerings, requirement lumpiness and requirement uncertainty were used to evaluate each lot-sizing procedures. A simulation model was used to test 810 observations. This research indicates that the LUCm and MOMm procedures outperform the traditional procedure when multiple discounts are available. In addition, for high discount attractiveness between the price breaks, the LCCm and MOMm procedures are more than five per cent better than the traditional procedure. When the discount attractiveness between the price breaks is low, there is very little difference in the performance of the alternative procedures. Moreover, the LUCm procedure requires 13 45 per cent fewer units of inventory than the MOMm procedure and 66.35 per cent fewer units than the traditional procedure. LUCm emerges as the procedure of choice for the multiple discount lot-sizing problem in material requirements planning (MRP) systems. The LUCm procedure is easily understood; it takes advantage of multiple discounts; it uses considerably less safety stock and places fewer orders.     

INFLUENCE OF SKIM MILK POWDER/RECODAN RS RATIO ON THE VISCOELASTICITY OF GROUNDNUT OIL-IN-WATER IMITATION MILKS

Imitation milks were prepared with different ratios of skim milk powder (SMP) and Recodan RS (R) as emulsifiers while keeping their total concentration constant. The ratio employed influenced the viscoelastic properties of the milks, as derived from creep compliance-time studies, the electrophoretic mobility of the oil drops and the interfacial tension between the oil and aqueous phases. Optimum values of the viscoelastic parameters were obtained when the SMP/R ratio was between 4/1 and 8/1. Association occurs between the SMP and R under these conditions and stabilization of the flocculated oil drops is primarily by a steric mechanism. During storage of the milks the viscoelastic parameters initially increased due to continued growth of the flocculated oil drop structures, but subsequently the parameters decreased as drop coalescence became the predominant factor.