Vcs Vincent Wiers

Unifying the theory and practice of production scheduling

Abstract The theory and practice of what has traditionally been called scheduling have been relatively close in some domains, while remaining worlds apart in others. Success at higher levels of production control has often been seen where the execution issues can be glossed over, especially in industries where there are prolonged periods of stability and maturity. Scheduling theory at the detailed level has been particularly successful in process industries or in situations where there are relatively few machines with significant setup issues. Unfortunately, the theory and practice have not been close in intermittent job shops or industries where there is inherent uncertainty or human judgment is necessary. This paper discusses the traditional scheduling problem and develops a framework based on the practice of scheduling that assists in understanding the requirements for an extended definition of scheduling that goes beyond the sequencing problem.

Integrated decision support for planning, scheduling, and dispatching tasks in a focused factory

Standard software for decision support in production control tasks is commonly structured according to the hierarchical production planning (HPP) concept. However, in a focused factory one planner may carry out planning, scheduling and dispatching. This paper presents a case study where one integrated planner is responsible for planning, scheduling and dispatching. Hence, the integrated planner needs a seamless system from the generation from the daily level through the generation of the 5-year-plan. This paper presents a design of a decision support system for the integrated planner.

A review of the applicability of OR and AI scheduling techniques in practice

This paper presents a review of the applicability of scheduling techniques in practice. Both the operations research and the artificial intelligence research communities have produced a number of reports on the applicability of techniques, often in isolation from each other, although the problems encountered seem largely similar in each case. Moreover, studies on the role of humans in production scheduling are reviewed. Papers that discuss the use of techniques by humans are also discussed. The paper suggests ways in which the applicability of scheduling techniques might be improved.

A review of capicity planning techniques within standard software packages

This paper gives a review of capacity planning techniques from which todays standard software packages for production control make their choice. The following techniques are discussed in the paper: four variants of the rough cut capacity check, capacity requirements planning with infinite and finite loading, input/output planning without and with individual work orders, and a number of sequencing techniques. An important issue throughout the paper is the concept of robustness and nervousness of planning techniques, Aspects of interaction between techniques and human planners arc given. The human planner is still an important factor in capacity planning.

A framework for decision support in production scheduling tasks

Production scheduling in industrial practice is still primarily a manual task, despite immense research efforts and the fact that manual scheduling is a very complex task. In this paper, the allocation of tasks between scheduling systems and human schedulers for various types of production units is addressed. The human factor in production scheduling is described using existing models from cognitive psychology. The allocation of scheduling sub-tasks is discussed, based on characteristics of human schedulers and scheduling systems. These sub-tasks are shown to depend on the type of production unit to be scheduled. Four case studies are described to illustrate the theoretical framework.

An empirical investigation of the neglect of MRP information by production planners

Production planning decisions are usually made by human planners that are assisted by decision support systems. While it is widely argued in the literature that current decision support systems for production planning are generally inadequate, it is not clear to what extent human planners actually disregard the planning decisions proposed by the system. In this study, we investigate this question. In a setting in which the planning systems model has an adequate representation of reality, we collect data on actual planning decisions and compare them to the planning decisions proposed by the system. We conclude that planners systematically and largely neglect the systems recommendations and that the extent of neglect is larger if the planning problem is more complex.

Warehouse manpower planning strategies in times of financial crisis : evidence from logistics service providers and retailers in the Netherlands

The economic crisis that is experienced in Europe has a large influence on transport and logistics companies. Since turnover typically drops strongly during a crisis, companies try to reduce costs in order to survive. The study reported in this paper has investigated how manpower planning in warehouses has been used to counter effects of the crisis and what the results are of the measures taken. A survey was carried out among warehouses run by retailers and logistics service providers. The results of the survey show that there is a significant relation between a decrease in turnover and the four investigated manpower planning strategies. Furthermore, the study shows that the most effective manpower planning strategies are flexible planning of employees and balancing the workload. Hence, the study concludes that in particular better operational planning is a key strategy to counter the effects of the financial crisis, which is an important insight for the management of warehouses.