Browsing by Author "Demir, Leyla"

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Citation - WoS: 45
Citation - Scopus: 56
An Adaptive Tabu Search Approach for Buffer Allocation Problem in Unreliable Non-Homogenous Production Lines
(Pergamon-Elsevier Science Ltd, 2012) Demir, Leyla; Tunali, Semra; Eliiyi Türsel, Deniz
The buffer allocation problem, i.e. how much buffer storage to allow and where to place it within the line, is an important research issue in designing production lines. In this study, a novel adaptive tabu search approach is proposed for solving buffer allocation problem in unreliable and non-homogeneous production lines. The objective is to maximize the throughput of the line, which is constrained by the capacity of each buffer space and also the total buffer capacity to allocate to these spaces. Besides proposing a new strategy to tune the parameters of tabu search adaptively during the search, an experimental study is carried out to select an intelligent initial solution scheme among three alternatives so as to decrease the search effort to obtain the best solutions. The performance of the proposed approach is evaluated by computational tests and very promising results are obtained. (C) 2011 Elsevier Ltd. All rights reserved.
Citation - WoS: 16
Citation - Scopus: 20
Capacity Improvement Using Simulation Optimization Approaches: a Case Study in the Thermotechnology Industry
(Taylor & Francis Ltd, 2015) Kose, Simge Yelkenci; Demir, Leyla; Tunali, Semra; Eliiyi Türsel, Deniz
In manufacturing systems, optimal buffer allocation has a considerable impact on capacity improvement. This study presents a simulation optimization procedure to solve the buffer allocation problem in a heat exchanger production plant so as to improve the capacity of the system. For optimization, three metaheuristic-based search algorithms, i.e. a binary-genetic algorithm (B-GA), a binary-simulated annealing algorithm (B-SA) and a binary-tabu search algorithm (B-TS), are proposed. These algorithms are integrated with the simulation model of the production line. The simulation model, which captures the stochastic and dynamic nature of the production line, is used as an evaluation function for the proposed metaheuristics. The experimental study with benchmark problem instances from the literature and the real-life problem show that the proposed B-TS algorithm outperforms B-GA and B-SA in terms of solution quality.
An Integrated Binary-Tabu Search Approach for the Buffer Allocation Problem: An Industrial Case Study
(Dime Univ Genoa, 2012) Demir, Leyla; Kose, Simge Yelkenci; Tunali, Semra; Eliiyi Türsel, Deniz
In this study, an integrated binary-tabu search algorithm is proposed to solve the buffer allocation problem for a real manufacturing system producing heating exchanger in Turkey. The aim is to minimize the total buffer size in the system while improving the system performance. To achieve this objective first the production system is modeled by using simulation. After that the proposed algorithm is employed to find the optimal buffer levels for minimizing the total buffer size in the system. The experimental study shows that proposed algorithm improves the current average daily throughput rate about 31.68%.
Citation - WoS: 117
Citation - Scopus: 149
The State of the Art on Buffer Allocation Problem: a Comprehensive Survey
(Springer, 2014) Demir, Leyla; Tunali, Semra; Eliiyi Türsel, Deniz
The buffer allocation problem is an NP-hard combinatorial optimization problem and it is an important research issue in designing manufacturing systems. The problem deals with finding optimal buffer sizes to be allocated into buffer areas in a production system to achieve a specific objective. This paper presents a comprehensive survey on buffer allocation problem in production systems. To provide a systematic review of current relevant research, first studies are grouped in two categories: 1. Reliable production lines, 2. Unreliable production lines. Next, the studies in each group are reviewed based on topology of the production line, the solution methodologies suggested and the objective function employed. The aim of this review is twofold. First, it provides an overview of recent advances in the field in order to highlight the new trends in solution methodology. Second, it presents ideas for future research by identifying gaps in the current literature.
Citation - WoS: 44
Citation - Scopus: 52
A Tabu Search Approach for Buffer Allocation in Production Lines With Unreliable Machines
(Taylor & Francis Ltd, 2011) Demir, Leyla; Tunali, Semra; Lokketangen, Arne
The optimal allocation of buffers is an important research issue in designing production lines. In this study, a tabu search (TS) algorithm is proposed to find near-optimal buffer allocation plans for a serial production line with unreliable machines. The main objective is to maximize the production rate, i.e. throughput, of the line. The efficiency of the proposed method is also tested to solve buffer allocation problems with the objective of total buffer size minimization. To estimate the throughput of the line with a given specific buffer allocation, an analytical decomposition approximation method is used. The performance of the tabu search algorithm is demonstrated on existing benchmark problems. The results obtained by the TS algorithm are clearly encouraging, as the TS algorithm is much better than the other algorithms for all considered benchmark problems.
Citation - WoS: 15
Citation - Scopus: 18
Two Approaches for Solving the Buffer Allocation Problem in Unreliable Production Lines
(Pergamon-Elsevier Science Ltd, 2013) Demir, Leyla; Tunali, Semra; Eliiyi Türsel, Deniz; Lokketangen, Arne
This paper presents an integrated approach to solve the buffer allocation problem in unreliable production lines so as to maximize the throughput rate of the line with minimum total buffer size. The proposed integrated approach has two control loops; the inner loop and the outer loop. While the inner loop control includes an adaptive tabu search algorithm proposed by Demir et al. [8], binary search and tabu search are proposed for the outer loop. These nested loops aim at minimizing the total buffer size to achieve the desired throughput level. To improve the efficiency of the proposed tabu search, alternative neighborhood generation mechanisms are developed. The performances of the proposed algorithms are evaluated by extensive computational experimentation, and the results are reported. (C) 2013 Elsevier Ltd. All rights reserved.