Management Information Systems

Permanent URI for this collectionhttps://hdl.handle.net/10679/7976

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Browsing by Author "Doğru, M. K."

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    Heuristic methods for the capacitated stochastic lot-sizing problem under the static-dynamic uncertainty strategy
    (Elsevier, 2019-09) Randa, A. C.; Doğru, M. K.; Iyigun, C.; Özen, Ulaş; Management Information Systems; ÖZEN, Ulaş
    We consider a lot-sizing problem in a single-item single-stage production system facing non-stationary stochastic demand in a finite planning horizon. Motivated by common practice, the set-up times need to be determined and frozen once and for all at the beginning of the horizon while decisions on the exact lot sizes can be deferred until the setup epochs. This operating scheme is referred to as the static-dynamic uncertainty strategy in the literature. It has been shown that a modified base stock policy is optimal for a capacitated system with minimum lot size restrictions under the static-dynamic uncertainty strategy. However, the optimal policy parameters require an exhaustive search, for which the computational time grows exponentially in the number of periods in the planning horizon. In order to alleviate the computational burden for real-life size problems, we developed and tested seven different heuristics for computational efficiency and solution quality. Our extensive numerical experiments showed that average optimality gaps less than 0.1% and maximum optimality gaps below 4% can be attained in reasonable running times by using a combination of these heuristics.
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    Tactical inventory planning at alcatel-lucent’s repair and exchange services
    (Informs, 2015-05-01) Doğru, M. K.; Özen, Ulaş; Management Information Systems; ÖZEN, Ulaş
    Alcatel-Lucent, a major telecommunications equipment manufacturer, provides equipment, solutions, and services to customers worldwide. Post-sales support services are a growing business segment for the company, and require significant investment in spare parts. The inventory investment constitutes a considerable portion of the total cost of providing post-sales support services for new customer contracts; it is also an important element in estimating new contract offerings and evaluating and redesigning business processes that affect inventories. Because of Alcatel-Lucent's two-echelon supply chain structure, inventory sizing for post-sales support services is a complicated task that spreadsheet applications cannot handle adequately. Thus, the company's repair and exchange services (RES) group needed a fast, user-friendly, and generic software solution with advanced analytic capabilities to support its business tendering and evaluation processes. To meet this requirement, we developed the tactical inventory planning tool, which uses stochastic modeling and optimization algorithms, for this purpose. Although the tool's primary function is to support the RES business tendering process, it has also been useful in other business analysis because of its generic nature.