Endüstri Mühendisliği / Industrial Engineering
Recent Submissions
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A mathematical characterization of the gel point in sol-gel transition
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Publisher and Date:(IOP Publishing Ltd, 2015)We model the sol-gel transition in terms of Susceptible-Infected-Removed (SIR) and Susceptible-Exposed-Infected-Removed (SEIR) models and compare with experimental results. We show, numerically, that the "gel point" described as the onset of the gelation phenomena and measured experimentally, corresponds to an accumulation point of the extreme values of the derivatives of the gelation curve. We define the "critical point of a sigmoidal curve" as the limit of the points where the derivatives reach ...
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On the uniqueness of epidemic models fitting a normalized curve of removed individuals
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Publisher and Date:(Springer Heidelberg, 2015)The susceptible-infected-removed (SIR) and the susceptible-exposed-infected-removed (SEIR) epidemic models with constant parameters are adequate for describing the time evolution of seasonal diseases for which available data usually consist of fatality reports. The problems associated with the determination of system parameters starts with the inference of the number of removed individuals from fatality data, because the infection to death period may depend on health care factors. Then, one ...
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AHP-BASED APPROACH TO EVALUATE SOLAR POWER PLANT LOCATION ALTERNATIVES
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Publisher and Date:(Intl Inst Social & Economic Sci, 2016)Solar energy is the most readily available source of energy, and one of the most important sources of the renewable energy, because it is non-polluting and helps in lessening the greenhouse effect. Main problem of establishing a solar power plant is to determine its location. In the presence of many location alternatives and evaluation criteria, a multiple-criteria decision making problem arises. In this work, the location problem will be solved by using analytic hierarchy process (AHP) to figure ...
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On the uniqueness of the octonionic instanton solution on conformally flat 8-manifolds
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Publisher and Date:(IOP Publishing Ltd, 2016)Let M be an 8-manifold and E be an SO(8) bundle on M. In a previous paper [F. Ozdemir and A.H. Bilge, "Self-duality in dimensions 2n > 4: equivalence of various definitions and the derivation of the octonionic instanton solution", ARI (1999) 51:247-253], we have shown that if the second Pontrjagin number p(2) of the bundle E is minimal, then the components of the curvature 2-form matrix F with respect to a local orthonormal frame are F-ij = c(ij)omega(ij), where c(ij)'s are certain functions and ...
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Modeling of Wind Effects on Stratified Flows in Open Channels: A Model for the Istanbul Strait (Bosphorus)
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Publisher and Date:(2016)Stratified flows in open channels arise as a result of density or surface level differences. If the channel is connected to a basin at one or both ends, strong winds originating from the basin cause the "wind setup" effect that increases the water level at the entrance of the channel. On the other hand, along the channel, persistent winds in the upper layer flow direction lead to an increase of the drift velocity and to a decrease in upper layer flow depth. The Istanbul Strait (Bosphorus) connecting ...
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Generation/transmission investment planning integrated with market equilibrium models in electricity markets
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Publisher and Date:(IEEE, 2017)This paper introduces integrated models for transmission investments anticipating the generation investments and market-clearing equilibrium. Market-clearing models for deregulated electricity markets can inform decision makers on price signals formed in the competitive market, other investor's and/or generator's behaviors underlying these price signals and new generation/transmission investment decisions. Bi-level programming problems are formed for this integrated models and reformulated by using ...
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Self-duality in higher dimensions
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Publisher and Date:(IOP Publishing Ltd, 2017)Let w be a 2-form on a 2n dimensional manifold. In previous work, we called w "strong self-dual, if the eigenvalues of its matrix with respect to an orthonormal frame are equal in absolute value. In a series of papers, we showed that strong self-duality agrees with previous definitions; in particular if w is strong self-dual, then, in 2n dimensions, w(n) is proportional to its Hodge dual w and in 4n dimensions, w(n) is Hodge self-dual. We also obtained a local expression of the Bonan 4-form on 8 ...
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Reformulations of a Bilevel Model for Detection of Tacit Collusion in Deregulated Electricity Markets
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Publisher and Date:(IEEE Computer Society, 2019)In this study, we consider a collusion model for competitive pool based electricity markets operated by an independent system operator (ISO), where it aims to prevent tacit collusion among generators. In order to determine the existence of tacit collusion in the market, we have employed the the game-Theoretic bilevel optimization model proposed by [1]. This model represents the market clearing mechanism, where generators determine their bids in order to maximize their profit while the system ...
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A Comparative Study of Energy Models for Turkish Electricity Market Using LEAP
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Publisher and Date:(IEEE Computer Society, 2019)Fossil fuel thermal power plants constitute a large part of the Turkish electricity generation capacity. Turkish government has been developing several energy policy documents to evaluate how various renewable energy sources of the country can be utilized optimally in the generation of electricity within the next 30 years. This study considers three scenarios in the transition to renewable energy for Turkey; the business as usual (BAU), energy conservation (EC) and renewable energy (REN) scenarios. ...
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Evaluation Of Water Supply Alternatives For Istanbul Using Forecasting And Multi-Criteria Decision Making Methods
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Publisher and Date:(Elsevier Ltd, 2020)Water scarcity is one of the most serious problems of the future due to increasing urbanization and water demand. Urban water planners need to balance increasing water demand with water resources that are under increasing pressure due to climate change and water pollution. Decision makers are forced to select the most appropriate water management alternative with respect to multiple, conflicting criteria based on short and long term projections of water demand in the future. In this paper, we ...
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Forecasting Models For Daily Natural Gas Consumption Considering Periodic Variations And Demand Segregation
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Publisher and Date:(Elsevier Ltd, 2020)Due to expensive infrastructure and the difficulties in storage, supply conditions of natural gas are different from those of other traditional energy sources like petroleum or coal. To overcome these challenges, supplier countries require take-or-pay agreements for requested natural gas quantities. These contracts have many pre-clauses; even if they are not met due to low/high consumption or other external factors, buyers must completely fulfill them. A similar contract is then imposed on ...
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An Intelligent Approach For The Evaluation Of Transformers In A Power Distribution Project
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Publisher and Date:(IOS Press BV, 2020)In this study, a hybrid approach is presented for the evaluation and selection of transformers in a power distribution project. Ranking transformers and selecting the best among alternatives is a complex multiple criteria decision making (MCDM) problem with various possibly conflicting quantitative and qualitative criteria. In this research, two hesitant fuzzy MCDM methods; hesitant fuzzy Analytic Hierarchy Process (hesitant F-AHP) and hesitant fuzzy Preference Ranking Organization Method for ...
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An Integrated Fuzzy Best-Worst-TOPSIS Method for Evaluation of Hotel Website and Digital Solutions Provider Firms
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Publisher and Date:(Hindawi Limited, 2020)In todays world where technology is rapidly evolving, hotels need to be the best in all conditions to be one step ahead of other competitors. Digital marketing and hotel website solutions play a lead role in this competition. Therefore, hotel websites need to be innovative, user-friendly, and descriptive. The main purpose of the study is to evaluate and rank potential hotel websites and digital solutions provider firms. Since there are various potentially competing quantitative and qualitative ...
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True variable-depth milling
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Publisher and Date:(Elsevier B.V., 2020)When tool wears during machining, cost of the process increases. Rapid tool wear leads to even further contributions to process cost and hence must be taken well care of. Among the many forms of tool wear, notch wear is one that has a big effect on the tool change decision. When the tool contacts the workpiece, a high amount of impact is created where depth of cut is. With continuous machining operations such as turning, the impact may not be as important; however, with interrupted machining ...
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An equivalence class decomposition of finite metric spaces via Gromov products
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Publisher and Date:(Elsevier Science Bv, 2017)Let (X, d) be a finite metric space with elements P-i, i = 1,..., n and with the distance functions d(ij) The Gromov Product of the "triangle" (P-i, P-j, P-k) with vertices P-t, P-j and P-k at the vertex Pi is defined by Delta(ijk) = 1/2(d(ij) + d(ik) - d(jk)). We show that the collection of Gromov products determines the metric. We call a metric space Delta-generic, if the set of all Gromov products at a fixed vertex P-i has a unique smallest element (for i = 1,., n). We consider the function ...
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Flow Structure in a Shallow Mixing Layer Developing over 2-D Dunes
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Publisher and Date:(E D P Sciences, 2018)A high resolution Detached Eddy Simulation (DES) are used to characterize the evolution of a shallow mixing layer developing between two parallel streams in a long open channel over two-dimensional (2D) dunes. The study discusses the vertical non-uniformity in the mixing layer and provides a quantitative characterization of the growth of the large-scale quasi 2D coherent structures with the distance from the splitter plate. The presence of large-scale roughness elements in the form of an array of ...
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A 'Regional Energy Hub' for achieving a low-carbon energy transition
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Publisher and Date:(Elsevier Sci Ltd, 2018)The transition to a low-carbon energy economy will remain a cornerstone of national energy policies of countries committed to the climate change accord for decades to come. We think that transmission investment is one key policy instrument amongst other to help with this transition. We propose an enhanced role for investing in transmission capacity for inter-regional trade to allow effective fuel switching among countries through a physically connected market. We develop a conceptual framework of ...
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A Fuzzy ANP-Based GRA Approach to Evaluate ERP Packages
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Publisher and Date:(IGI Global, 2019)One of the major problems that most companies face with during the implementation of an ERP system is to determine the best satisfying ERP software based on their needs and expectations. Because an improperly selected ERP software might lead to time loss and increased costs, and in the long run, a loss of market share. Therefore, the ERP evaluation process for companies becomes to a vital point. On the other hand, evaluating ERP software alternatives under a set of criteria leads us to a ...
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A fuzzy AHP-VIKOR approach for evaluation of educational use simulation software packages
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Publisher and Date:(IOS Press, 2019)In this study, an intelligent, integrated approach is presented to help educators select the best simulation software package. Selecting the best simulation software package for educational use is a complex multiple criteria decision making (MCDM) problem with several potentially conflicting quantitative and qualitative criteria. In this paper, two fuzzy MCDM methods; fuzzy Analytic Hierarchy Process (F-AHP) and fuzzy VIsekriterijumska optimizacija i KOmpromisno Resenje (F-VIKOR) are integrated ...
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A Comparative Study of Energy Models for Turkish Electricity Market Using LEAP
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Publisher and Date:(IEEE, 2019)Fossil fuel thermal power plants constitute a large part of the Turkish electricity generation capacity. Turkish government has been developing several energy policy documents to evaluate how various renewable energy sources of the country can be utilized optimally in the generation of electricity within the next 30 years. This study considers three scenarios in the transition to renewable energy for Turkey; the business as usual (BAU), energy conservation (EC) and renewable energy (REN) scenarios. ...
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