Browsing by Author "Rohleder, Thomas R."
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- ItemOpen AccessEconomic lot sizing for a continuous process(2001) Cooke, David L.; Rohleder, Thomas R.
- ItemOpen AccessGroup technology/cellular manufacturing: considering human resource and quality issues using computer simulation(1994) Eckstein, Astrid Louise Hammer; Rohleder, Thomas R.In today's fiercely competitive marketplace, firms are looking for ways to improve their profitability. A number of computer simulations comparing group technology/cellular manufacturing (GT/CM) to job shop or process layouts addressed this topic. However, each of these simulations ignored some of the most basic operating conditions said to give GT/CM its advantages: human resources and quality. This simulation study incorporates human resource issues such as learning and labour constraints, together with quality issues such as defect rate and defect discovery. The simulation results show that GT/CM significantly outperforms the process layout in almost every environmental setting. A firm employing pure GT/CM with variable demand, fewer workers, fewer defects and fast learning could potentially improve its profitability three ways: by increasing productivity and having less inventory and rework; by improving its customer service level through on-time, high quality performance; and by increasing capacity.
- ItemOpen AccessModeling patient service centers with simulation and system dynamics(Springer Verlag, 2007) Bischak, Diane; Rohleder, Thomas R.; Baskin, Leland B.We report on the use of simulation modeling for redesigning phlebotomy and specimen collection centers (or patient service centers) at a medical diagnostic laboratory. Research was performed in an effort to improve patient service, in particular to reduce average waiting times as well as their variability. Discrete-event simulation modeling provided valuable input into new facility design decisions and showed the efficacy of pooling sources of variation, particularly patient demand and service times. Initial performance of the redesigned facilities was positive; however, dynamic feedback within the system of service centers eventually resulted in unanticipated performance problems. We show how a system dynamics model might have helped predict these implementation problems and suggest some ways to improve results.
- ItemOpen AccessSimultaneous management of demand and supply in services(1997) Klassen, Kenneth John; Rohleder, Thomas R.
- ItemOpen AccessThe dynamics and control of operational risk(2004) Cooke, David L.; Rohleder, Thomas R.This research use cases, models and conceptual frameworks to provide insights into risks associated with complex operations. An important contribution of this research is to further understanding of risks dynamics in operational systems and to suggest how such operational risks might best be controlled. Although this research is primarily concerned with safety in industrial operations, risk in service operations is included within the overall conceptual framework, which focuses on risks arising from the interactions of human decision-makers with the operational system. The research has three major components. The first component includes a detailed case study and simulation model of a major industrial accident, the Westray mine disaster. This research demonstrates that a dynamic simulation model can capture the essential elements of the interactions between the human system, the production system, and the safety system. The model provides insights into the complex interactions that can lead to disaster and suggests valuable lessons for organizational learning. The second component of the research takes a systems view of the unexpected or unwanted events, called "incidents," that inevitably arise in an operational system. The research suggests that by learning from incidents, organizations can reduce risk and minimize loss. The elements of an effective system for learning from incidents are discussed, and the simulation model for the Westray mine disaster is extended to incorporate an incident learning system. Again, lessons for organizational learning are drawn from the results of this analysis. The third component of the research draws insights from the literature and from case studies to develop a conceptual model of operational risk and a framework for risk control. Besides case studies of operational failures drawn from the literature, this research also draws on a case study of operational improvements at a chemical manufacturing facility. This part of the research explores similarities between operational risk management and quality management, and suggests that an effective approach for some corporations might be to integrate operational risk control into a total quality management framework.
- ItemOpen AccessUsing Simulation Modeling to Improve Patient Flow at an Outpatient Orthopedic Clinic(Springer Verlag, 2011) Bischak, Diane; Rohleder, Thomas R.; Lewkonia, Peter; Duffy, Paul; Hendijani, RosaWe report on the use of discrete event simulation modeling to support process improvements at an orthopedic outpatient clinic. The clinic was effective in treating patients, but waiting time and congestion in the clinic created patient dissatisfaction and staff morale issues. The modeling helped to identify improvement alternatives including optimized staffing levels, better patient scheduling, and an emphasis on staff arriving promptly. Quantitative results from the modeling provided motivation to implement the improvements. Statistical analysis of data taken before and after the implementation indicate that waiting time measures were significantly improved and overall patient time in the clinic was reduced.