Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 5Citation - Scopus: 5Taking Advantage of a Diverse Set of Efficient Production Schedules: A Two-Step Approach for Scheduling With Side Concerns(Pergamon-Elsevier Science Ltd, 2013-08) Goren, Selcuk; Pierreval, HenriIn many practical scheduling problems, the concerns of the decision-maker may not be all known in advance and therefore may not be included in the initial problem definition as an objective function and/or as constraints. In such a case, the usual techniques of multi-objective optimization become inapplicable. To cope with this problem and to facilitate handling the concerns of the decision-maker, which can be implicit or qualitative, a dedicated methodological framework is needed. In this paper we propose a new two-step framework. First, we aim at obtaining a set of schedules that can be considered efficient with respect to a performance measure and at the same time different enough from one another to enable flexibility in the final choice. We formalize this new problem and suggest to address it with a multimodal optimization approach. Niching considerations are discussed for common scheduling problems. Through the flexibility induced with this approach, the additional considerations can be taken into account in a second step, which allows decision-makers to select an appropriate schedule among a set of sound schedules (in contrast to common optimization approaches, where usually a single solution is obtained and it is final). The proposed two-step approach can be used to handle a wide range of underlying scheduling problems. To show its potential and benefits we illustrate the framework on a set of hybrid flow shop instances that have been previously studied in the literature. We develop a multimodal genetic algorithm that employs an adapted version of the restricted tournament selection for niching purposes in the first step. The second step takes into account additional concerns of the decision-maker related to the ability of the schedules to absorb the negative effects due to random machine breakdowns. Our computational experiments indicate that the proposed framework is capable of generating numerous high-performance (mostly optimal) schedules. Additionally, our computational results demonstrate that the proposed framework provides the decision-maker a high flexibility in dealing with subsequent side concerns, since there are drastic differences in the capabilities of the efficient solutions found in Step 1 to absorb the negative impacts of machine breakdowns. (C) 2013 Elsevier Ltd. All rights reserved.Book Part Citation - Scopus: 1Green Magnetic Nanoparticles in Enzyme Immobilization(Elsevier, 2024) Dadi, Seyma; Alrifai, Wardishan Kassem; Öçsoy, IsmailEnzymes as highly efficient biocatalysts are widely used in various biotechnological sectors including cosmetic, textile, food, and detergent. However, their practical applications can be hampered due to high expense and challenges in the extraction, separation, and purification steps. Additionally, enzymes have limited activity and stability at high temperature and different pH values. Aiming to overcome these challenges, various nanoparticles (NPs) have been used as supporting matrices and carriers for enzyme immobilization. Among the NPs, in recent years, green magnetic nanoparticles (GMNPs) have attracted great attention as ideal support material for enzyme immobilization owing to their exceptional properties, such as their easy preparation, low toxicity, biocompatibility, and lower diffusion limitation. These properties enable the immobilized enzymes on GMNPs to be used in many different applications. This chapter aims to summarize the recent developments about enzyme immobilization on magnetic nanoparticles and GMNPs and their practical applications. © 2024 Elsevier B.V., All rights reserved.Book Part Citation - Scopus: 4A Bi-Criteria Approach to Scheduling in the Face of Uncertainty: Considering Robustness and Stability Simultaneously(Nova Science Publishers, Inc., 2014) Gören, Selçuk; Sabuncuoĝlu, Ihsan; Selcuk, GörenIt is possible to scrutinize impacts of uncertainty on schedules from two different perspectives. The flrst one has to do with the fact that schedules are required to main- tain high performance in the face of uncertainty. In other words, it is desired that their performances are insensitive to negative impacts of disruptions. We refer to this view- point as the robustness perspective. The second viewpoint is about another quality: when a schedule is executed in the shop floor, the realized schedule is required not to deviate much from its initial version. This is because many activities besides pro- duction are planned based on the production schedule. It is important that unforeseen disruptions affect the plans for these activities as little as possible. We refer to this viewpoint as the stability perspective. Even though a considerable body of literature has emerged on hedging schedules against the negative effects of unforeseen disrup- tions in the last two decades, few studies address the problem of scheduling under uncertainty from both the robustness and the stability perspectives at the same time. The nature of the relation between robustness and stability, the trade-off between them, the circumstances under which they conflict or reconcile need to be thoroughly inves- tigated. To this end, we propose a bi-criteria approach to simultaneously investigate the robustness and stability of production schedules. We consider proactive schedul- ing in a single machine environment with random processing times. We use the total expected flow time and the total variance of job completion times as the robustness and stability measures, respectively. The proposed o-constraint variants are exact methods to generate the set of all Pareto-optimal schedules. We also develop an algorithm to generate a flxed number (set by the decision-maker) of near-Pareto-optimal schedules to deflne the characteristics and the shape of the trade-off curve without generating the entire Pareto set. Our computational experiments indicate that the proposed algorithms are efflcient. © 2018 Elsevier B.V., All rights reserved.Article Citation - WoS: 17Citation - Scopus: 20A Mathematical Model With Piecewise Constant Arguments of Colorectal Cancer With Chemo-Immunotherapy(Pergamon-Elsevier Science Ltd, 2023) Bozkurt, Fatma; Yousef, Ali; Bilgil, Halis; Baleanu, DumitruWe propose a new mathematical model with piecewise constant arguments of a system of ODEs to investigate the growth of colorectal cancer and its response to chemo-immunotherapy. Our main target in this paper is to analyze and represent the I.S.'s (immune system) efficiency during the chemotherapeutic process. Therefore, we proved and illustrated the necessity of IL-2 that supports the immune system, especially in early-detected cases of tumor density. Thus, the constructed model has been divided into sub-systems: the cell populations, the effects of the medications doxorubicin, and IL-2 concentration.Firstly, we analyze the stability of the equilibrium points (disease-free and co-existing) using the RouthHurwitz criteria. In addition, our study has shown that the system undergoes period-doubling, stationary and Neimark-Sacker bifurcations based on specific conditions. In the end, we illustrate some simulations to assist the theory of the manuscript.