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1.
BAHRAM ALIDAEE 《Production and Operations Management》1994,3(2):133-147
This is a study of a single-machine scheduling problem with the objective of minimizing the sum of a function of earliness and tardiness called the earliness and tardiness (ET) problem. I will show that if priority weights of jobs are proportional to their processing times, and if earliness and tardiness cost functions are linear, the problem will be equivalent to the total weighted tardiness problem. This proves that the et problem is np -hard. In addition, I present a heuristic algorithm with worst case bound for the et problem based on the equivalence relation between the two. When earliness and tardiness cost functions are quadratic, I consider the problem for a common due date for all jobs and for different job due dates. In general, the et problem with quadratic earliness and tardiness cost functions and all job weights equal to one is np -hard. I show that in many cases, when weights of jobs are proportional to their processing times, the problem can be solved efficiently. In the published results on the et problem with quadratic earliness and tardiness cost functions other researchers have assumed a zero starting time for the schedule. I discuss the advantages of a nonzero starting time for the schedule. 相似文献
2.
FRED F. EASTON DONALD F. ROSSIN WILLIAM S. BORDERS 《Production and Operations Management》1992,1(2):159-174
The persistent shortage of nurses adversely affects the productivity, quality of care, and operating costs in most acute care hospitals. Aggravating the shortage are high nurse turnover rates, approaching 200% in some institutions. Policies to ensure adequate staffing levels and provide more attractive work schedules are alleged to improve nurse retention. However, their cost is seldom discussed. We compared expected nursing expense and workforce requirements to staff eight medical and surgical nursing units of a large hospital for 1 month, under 12 different scheduling policies alleged to improve turnover. Using simulation and an integrated staffing and scheduling methodology, we found that the expected nursing wages and workforce requirements for some policies differed by as much as 33%. In this hospital, the expected labor costs for certain policies could erode the benefits expected from improved retention. In contrast, other policies appear to allow high utilization of nursing resources, enhancing the expected benefits of reduced turnover with significant reductions in expenses for labor, recruiting, training, and fringe benefits. 相似文献
3.
RAM NARASIMHAN JAYANTH JAY ARAM AND JOSEPH R. CARTER 《Production and Operations Management》2001,10(1):1-15
The importance of evaluating the effectiveness of the purchasing function in firms along multiple criteria has attracted considerable attention. However, few studies have identified the defining elements that constitute purchasing competence. This paper introduces the construct of purchasing competence using a second‐order factor structure derived from purchasing practices identified from the literature. The validity of the construct (purchasing competence) is tested using data from a sample of 179 firms. The results indicate (1) the construct validity of purchasing competence and (2) the predictive validity of purchasing competence, which has a significant positive influence on total quality management performance and customer satisfaction. The implications of these findings for additional research are discussed. 相似文献
4.
This paper investigates the performance impact of lot‐sizing rule (LSR) selection and freezing of the master production schedule (MPS) in multi‐item single‐level systems with a single resource constraint under deterministic demand. The results of the study show that the selection of LSRS and the parameters for freezing the MPS have a significant impact on total cost, schedule instability, and the service level of the system. However, the selection of LSRS does not significantly influence the selection of the MPS freezing parameters. The basic conclusions concerning the performance of the freezing parameters under a capacity constraint agreed with previous research findings without consideration of capacity constraints. 相似文献
5.
This research investigated the value of protecting the continuity of release batchs in a transfer batching environment, by modifying the SPT rule. A simulation model of a job shop was used to test the modified SPT rule. The performance measures evaluated were mean flow time, flow time variance, and mean lateness. Conditions under which the SPT modification improved results were as follows: large number of transfer batches, small setup time to process time ratio, and large variation in process times from station to station. The results suggest that shop loading is not a significant factor affecting performance of the modified SPT rule. 相似文献
6.
T. C. EDWIN CHENG CHELLIAH SRISKANDARAJAH GUOQING WANG 《Production and Operations Management》2000,9(4):367-378
In this paper we study the time complexities of some two‐ and three‐stage no‐wait flowshop makespan scheduling problems where, in some stage, all the jobs require a constant processing time and the stage may consist of parallel identical machines. Polynomial time algorithms are presented for certain problems, while several others are proved to be strongly NP‐complete. 相似文献
7.
Cognitive Style and the Theory and Practice of Individual and Collective Learning in Organizations 总被引:1,自引:0,他引:1
This paper reviews aspects of two largelydisparate literatures from the adjacent fields ofindividual and organizational learning and identifiessome implications for theory and practice. The focus of attention is the extent to which the individuallevel construct cognitive style can be meaningfullyapplied to aid the understanding of learning at thelevel of the organization as well as at the level of the individual. Attention is given to theways in which consideration of cognitive style canimprove the effectiveness of interventions designed toimprove individual and organizational performance. Nine categories of intervention areidentified. 相似文献
8.
JEFFREY W. HERRMANN CHUNG-YEE LEE JIM HINCHMAN 《Production and Operations Management》1995,4(1):30-45
This paper describes a global job shop scheduling procedure that uses a genetic algorithm to find a good schedule. Unlike previously considered algorithms, this procedure has been implemented in the scheduling system for a manufacturing facility and has led to improved scheduling. This facility is a semiconductor test area. The test area is a job shop and has sequence-dependent setup times at some operations. The concern of management is to meet their customer due dates and to increase throughput. This requires the coordination of many resources, a task beyond the ability of simple dispatching rules. We discuss a centralized procedure that can find a good schedule through the use of a detailed scheduling model and a genetic algorithm that searches over combinations of dispatching rules. We discuss our effort in developing a system that models the shop, creates schedules for the test area personnel, and makes a number of contributions to test area management. 相似文献
9.
THOMAS MORTON VENKATESH NARAYAN PRASAD RAMNATH 《Production and Operations Management》1995,4(2):94-107
We give a tutorial on bottleneck dynamics. Bottleneck dynamics is a scheduling framework that uses approximate dual resource prices to make decentralized decisions. The basic idea is to establish a price for a resource as a function of the set of jobs that need to be processed by the resource. Tasks are then sequenced according to a cost/benefit ratio. Starting with one resource sequencing problems, we describe how priorities for jobs can be developed and how they translate into resource prices. We then describe how resource prices can be approximated in a multiresource situation and how lead times which are critical for these approximations can be accurately computed. We also describe a number of studies that have shown bottleneck dynamics to be an effective approach in several different problem areas. 相似文献
10.
Operational-level scheduling decisions on the factory floor include the release policy and the dispatching rule. Recent work by researchers suggests that factory performance depends heavily on the release policy. Several heuristic factory release rules have been developed that generate release decisions based on the status of the bottleneck machine. The heuristic rules perform very well in reducing the work-in-process inventory. However, factory output schedules generated by these rules generally fail to match the demand pattern, creating excessive finished goods inventory and/or excessive backorders. To overcome these difficulties, a computationally efficient integer programming model is proposed for release scheduling. 相似文献