A. Akbalik - Academia.edu (original) (raw)
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Papers by A. Akbalik
2014 International Conference on Control, Decision and Information Technologies (CoDIT), 2014
This paper presents two polynomial time algorithms for the constant capacitated lot sizing proble... more This paper presents two polynomial time algorithms for the constant capacitated lot sizing problem with a batch production. We give several optimality properties for the general problem. Assuming constant production capacity, constant batch size and Wagner-Whitin cost structure, we derive O(T 4 ) and O(T 6 ) time algorithms respectively for the case with production capacity multiple of the batch size and for the case with arbitrary fixed capacities.
ABSTRACT We study a multi-item lot sizing problem with inventory bounds, where the production of ... more ABSTRACT We study a multi-item lot sizing problem with inventory bounds, where the production of the items is uncapacitated but a storage capacity is considered, limiting at each period the amount of products that can be held in stock. We prove that the problem is strongly NP-hard even with no holding cost and stationary setup costs. For non-speculative costs, this lot-sizing problem remains NP-hard even when restricted to only 2 periods. However, in this case, we show that it can be polynomially solved for any fixed number of items.
Optimization Letters, 2014
ABSTRACT We study a multi-item lot sizing problem with inventory bounds, where the production of ... more ABSTRACT We study a multi-item lot sizing problem with inventory bounds, where the production of the items is uncapacitated but a storage capacity is considered, limiting at each period the amount of products that can be held in stock. We prove that the problem is strongly NP-hard even with no holding cost and stationary setup costs. For non-speculative costs, this lot-sizing problem remains NP-hard even when restricted to only 2 periods. However, in this case, we show that it can be polynomially solved for any fixed number of items.
International Journal of Production Research - INT J PROD RES, 2011
In this article, a comparative discussion between just-in-time (JIT) and time window (TW) policie... more In this article, a comparative discussion between just-in-time (JIT) and time window (TW) policies is performed for a special case of the single-item capacitated lot sizing problem (CLSP), in which two storage levels are available, including plant and customer levels. In the JIT policy, the customer demand has to be satisfied on the due date of the demand, however, in the TW policy, the shipment can be made a few days before the due date. The influence of the two policies on the total cost is studied for a structure of a single capacitated plant which replenishes a customer, both having storage spaces. Both planning problems are shown to be NP-hard using the well-known CLSP which constitutes their subpart. A mixed integer linear program and a pseudo-polynomial dynamic program are proposed for each policy. The objective of this article is first to solve the TW problem to the optimality and, second to show the gain obtained by TW policy in terms of cost reduction. For the benchmark, w...
2014 International Conference on Control, Decision and Information Technologies (CoDIT), 2014
This paper presents two polynomial time algorithms for the constant capacitated lot sizing proble... more This paper presents two polynomial time algorithms for the constant capacitated lot sizing problem with a batch production. We give several optimality properties for the general problem. Assuming constant production capacity, constant batch size and Wagner-Whitin cost structure, we derive O(T 4 ) and O(T 6 ) time algorithms respectively for the case with production capacity multiple of the batch size and for the case with arbitrary fixed capacities.
ABSTRACT We study a multi-item lot sizing problem with inventory bounds, where the production of ... more ABSTRACT We study a multi-item lot sizing problem with inventory bounds, where the production of the items is uncapacitated but a storage capacity is considered, limiting at each period the amount of products that can be held in stock. We prove that the problem is strongly NP-hard even with no holding cost and stationary setup costs. For non-speculative costs, this lot-sizing problem remains NP-hard even when restricted to only 2 periods. However, in this case, we show that it can be polynomially solved for any fixed number of items.
Optimization Letters, 2014
ABSTRACT We study a multi-item lot sizing problem with inventory bounds, where the production of ... more ABSTRACT We study a multi-item lot sizing problem with inventory bounds, where the production of the items is uncapacitated but a storage capacity is considered, limiting at each period the amount of products that can be held in stock. We prove that the problem is strongly NP-hard even with no holding cost and stationary setup costs. For non-speculative costs, this lot-sizing problem remains NP-hard even when restricted to only 2 periods. However, in this case, we show that it can be polynomially solved for any fixed number of items.
International Journal of Production Research - INT J PROD RES, 2011
In this article, a comparative discussion between just-in-time (JIT) and time window (TW) policie... more In this article, a comparative discussion between just-in-time (JIT) and time window (TW) policies is performed for a special case of the single-item capacitated lot sizing problem (CLSP), in which two storage levels are available, including plant and customer levels. In the JIT policy, the customer demand has to be satisfied on the due date of the demand, however, in the TW policy, the shipment can be made a few days before the due date. The influence of the two policies on the total cost is studied for a structure of a single capacitated plant which replenishes a customer, both having storage spaces. Both planning problems are shown to be NP-hard using the well-known CLSP which constitutes their subpart. A mixed integer linear program and a pseudo-polynomial dynamic program are proposed for each policy. The objective of this article is first to solve the TW problem to the optimality and, second to show the gain obtained by TW policy in terms of cost reduction. For the benchmark, w...