Browsing by Author "Bulut, Onder"

Now showing 1 - 4 of 4

Citation - WoS: 3
Citation - Scopus: 7
A Differential Evolution Algorithm for the Economic Lot Scheduling Problem
(IEEE, 2011) Tasgetiren, M. Fatih; Bulut, Onder; Fadiloglu, M. Murat
In this study we provide a Differential Evolution (DE) based heuristic to solve the Economic Lot Scheduling Problem (ELSP) under basic period approach. The problem is to find the best cyclic production schedule of n items to be produced on a single machine such that the production cycle of each item is an integer multiple of the basic period. The demand and the production rates are deterministic and known in advance. Our computational results suggest that our algorithm is competitive with the existing genetic algorithm, and therefore it is promising for the solution of a generalized version of the problem which is called extended basic period approach in the future.
Citation - WoS: 7
Citation - Scopus: 15
A Discrete Artificial Bee Colony Algorithm for the Economic Lot Scheduling Problem
(IEEE, 2011) Tasgetiren, M. Fatih; Bulut, Onder; Fadiloglu, M. Murat
In this study we present a discrete artificial bee colony (DABC) algorithm to solve the economic lot scheduling problem (ELSP) under extended basic period (EBP) approach and power-of-two (PoT) policy. In specific, our algorithm provides a cyclic production schedule of n items to be produced on a single machine such that the production cycle of each item is an integer multiple of a fundamental cycle. All the integer multipliers are in the form of power-of-two, and under EBP approach feasibility is guaranteed with a constraint that checks if the items assigned in each period can be produced within the length of the period. For this problem, which is NP-hard, our DABC algorithm employs a multi-chromosome solution representation to encode power-of-two multipliers and the production positions separately. Both feasible and infeasible solutions are maintained in the population through the use of some sophisticated constraint handling methods. A variable neighborhood search (VNS) algorithm is also fused into DABC algorithm to further enhance the solution quality. The experimental results show that the proposed algorithm is very competitive to the best performing algorithms from the existing literature under the EBP and PoT policy.
Citation - WoS: 20
Citation - Scopus: 22
An Embedded Markov Chain Approach To Stock Rationing
(Elsevier Science Bv, 2010) Fadiloglu, Mehmet Murat; Bulut, Onder
We propose a new method for the analysis of lot-per-lot inventory systems with backorders under rationing. We introduce an embedded Markov chain that approximates the state-transition probabilities. We provide a recursive procedure for generating these probabilities and obtain the steady-state distribution. (C) 2010 Elsevier B.V. All rights reserved.
Citation - WoS: 16
Citation - Scopus: 18
Production Control and Stock Rationing for a Make-To System With Parallel Production Channels
(Taylor & Francis Inc, 2011) Bulut, Onder; Fadiloglu, Mehmet Murat
This article considers the problem of production control and stock rationing in a make-to-stock production system with lost sales, multiple servers in parallel production channels, and several customer classes. It is assumed that independent stationary Poisson demand streams and exponential service times are in operation. At decision epochs, the control specifies whether or not to increase the number of active servers in conjunction with the stock allocation decision. Previously placed production orders cannot be cancelled. The system is modeled as an M/M/s make-to-stock queue, and properties of the optimal cost function and of the optimal production and rationing policies are characterized. It is shown that the optimal production policy is a state-dependent base-stock policy, and the optimal rationing policy is of threshold type. Furthermore, it is shown that the rationing levels are non-increasing in the number of active channels. It is also shown that the optimal ordering policy transforms into a bang-bang type policy when the model is relaxed by allowing order cancellations. Another model with partial order-cancellation flexibility is provided to fill the gap between the no-flexibility and the full-flexibility models. The additional gain that the optimal policy provides over the suboptimal base-stock policy proposed in the literature is qualified along with the value of the flexibility to cancel production orders.