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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Shift scheduling in call centers with multiple skill sets and transportation costs(IEEE, 2007) Emil, Emre; Department of Industrial Engineering; Department of Industrial Engineering; Örmeci, Lerzan; Salman, Fatma Sibel; Faculty Member; Faculty Member; Department of Industrial Engineering; College of Engineering; College of Engineering; 32863; 178838Workforce plans in call centers, mostly working 24 hours a day and 7 days a week, have to sAtışfy both custÖmer service levels and personnel constraints. Moreover, in large metropolitans such as Istanbul, call centers provide the transportation of the staff, so that shuttle costs constitute a major part of the total operational costs. We present a mathematical model which minimizes the transportation costs while sAtışfying service level and personnel constraints. We test our model with data from call centers.Publication Metadata only Surgical case-mix and discharge decisions: does within-hospital coordination matter?(The Institute for Operations Research and the Management Sciences (INFORMS), 2022) Bavafa, Hessam; Savin, Sergei; Virudachalam, Vanitha; Department of Industrial Engineering; Örmeci, Lerzan; Faculty Member; Department of Industrial Engineering; College of Engineering; 32863We study the problem faced by a profit-maximizing, resource-constrained hospital that controls patient inflows by designing a case-mix of its elective procedures and patient outflows via patient discharges. At the center of our analysis is the model that evaluates hospital profit for any combination of elective portfolio and patient discharge policies. Our model analyzes the impact of patient flow management decisions on the utilization of two main classes of hospital resources: "front end" (e.g., operating rooms) and "backroom" (e.g., recovery beds). We introduce a new approach for modeling the patient recovery process and use it to characterize the relationship between patient length of stay and probability of readmission. Using this modeling approach, we develop a two moment approximation for the utilization of front-end and backroom resources. We focus on assessing the benefits associated with the hospital employing a coordinated decision making process in which both portfolio and discharge decisions are made in tandem. Specifically, we compare the hospital's profits in the coordinated setting to those under two decentralized approaches: a front-end approach, under which both decisions are made based exclusively on the front-end costs, and a "siloed" approach, in which discharge decisions are made based on backroom costs and the case-mix is determined as the optimal match for the discharge policy. We show that hospitals operating under the front-end policy can significantly benefit from coordination when backroom costs are sufficiently high even if they do not exceed surgical costs. on the other hand, for hospitals operating under the siloed policy, coordination brings significant benefits only when surgical costs are high and significantly dominate the cost structure.Publication Metadata only Contributions to stochastic models of manufacturing and service operations(Taylor & Francis, 2018) Liberopoulos, George; Heavey, Cathal; Helber, Stefan; Matta, Andrea; Department of Industrial Engineering; Karaesmen, Fikri; Faculty Member; Department of Industrial Engineering; College of Engineering; 3579N/A