dc.contributor.advisor | Gürler, Ülkü | |
dc.contributor.author | Poormoaied, Saeed | |
dc.date.accessioned | 2018-12-05T11:31:45Z | |
dc.date.available | 2018-12-05T11:31:45Z | |
dc.date.copyright | 2018-10 | |
dc.date.issued | 2018-11 | |
dc.date.submitted | 2018-12-03 | |
dc.identifier.uri | http://hdl.handle.net/11693/48190 | |
dc.description | Cataloged from PDF version of article. | en_US |
dc.description | Thesis (Ph.D.): Bilkent University, Department of Industrial Engineering, İhsan Doğramacı Bilkent University, 2018. | en_US |
dc.description | Includes bibliographical references (leaves 178-182). | en_US |
dc.description.abstract | Many inventory systems hold items which perish after a specific time. Upon
perishing, the inventory level falls down to zero which may incur irreparable
costs to the system. Therefore, developing a genius control policy for managing
such inventories is a crucial task. Since the lifetime of items are now affecting the
inventory level, applying the traditional inventory policies which are based only on
the stock level causes some shortcomings. The traditional inventory policies lack
the information regarding the lifetime of items. On the other hand, the optimal
policy for perishable items is known to be a periodic review policy keeping the
complete information regarding the remaining lead times of orders, inventory onhand,
and lifetimes of items. Optimal control policy class for continuous review
is still an open question. In this regard, we attempt to contribute the remaining
lifetime of items into the inventory policy for perishable items with positive lead
time and fixed lifetime under a continuous review with a service level constraint.
We develop a class of hybrid control policies which utilize the remaining lifetimes
of items in addition to stock levels. We study a stochastic single item inventory
system where demand follows a Poisson process and unmet demand is lost. The
aging process of a new batch starts when it joins the inventories. We provide
an exact analytic model by using an embedded Markov chain process to derive
the stationary distribution of the effective lifetimes in the presence of both one
and more than one outstanding orders assumptions. Operating characteristics
of the system are derived using the renewal reward theorem. Additionally, we
propose some control policies based on only the remaining lifetime of items. Our
results reveal that the hybrid policies consistently outperform the stock level and
remaining lifetime-based polices, especially when demand during the lifetime is
sufficiently small and unit perishing cost is high. It is observed that the dominance
relations among these two policy classes depend on the particular parameter
setting. In particular, when the lifetime of items is long enough, the stock level
based policy performs very well. Finally, we present our methodology for finding
the optimal solution thorough a heuristic algorithm derived by considering the
structure of the objective function and service level constraint, and a sensitivity
analysis is performed to evaluate the impact of the key input parameters. | en_US |
dc.description.statementofresponsibility | by Saeed Poormoaied | en_US |
dc.format.extent | xvi, 185 leaves : charts ; 30 cm. | en_US |
dc.language.iso | English | en_US |
dc.rights | info:eu-repo/semantics/openAccess | en_US |
dc.subject | Perishable Inventory | en_US |
dc.subject | Inventory Policy | en_US |
dc.subject | Effective Lifetime | en_US |
dc.subject | Embedded Markov Chain | en_US |
dc.subject | Renewal Theorem | en_US |
dc.title | Age and lifetime based policies for perishable items | en_US |
dc.title.alternative | Kısa ömürlü ürünler için yaş ve raf ömrüne dayalı politikalar | en_US |
dc.type | Thesis | en_US |
dc.department | Department of Industrial Engineering | en_US |
dc.publisher | Bilkent University | en_US |
dc.description.degree | Ph.D. | en_US |
dc.identifier.itemid | B159216 | |