Endüstri Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://gcris.khas.edu.tr/handle/20.500.12469/48

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Citation Count: 0
The stability constants of the rare earth complexes with trimetaphosphoric acid
(Soc Chimica Italiana, 2001) Şungur, Şana Kutun
The stability constants of the complexes formed between the rare earth metal ions and the anion of trimetaphosphoric acid have been determined at a temperature of 20 degreesC and an ionic strength of mu =0.1 by the ion-exchange equilibrium method. The investigations indicate that stabilities of complexes increased from La to Lu.The highest and the lowest stability constant values (beta) were found to be 7.76 and 3.82 for Lu3+ and La3+ respectively.
Citation Count: 0
Chelate extraction of transition metal ions by ethylene diamine diacetic acid with n-substituted octadecyl groups
(Taylor & Francis Inc, 2002) Bıçak, Niyazi; Şungur, Şana Kutun; Tan, Nükhet; Gazi, Mustafa
An organic-soluble chelating agent NN'-di-n-octadecyl ethylenediamine-NN'-diacetic acid (DOED) has been synthesized in two steps by (i) condensation of dibromoethane with 1-amino octadecane (octadecylamine) and (ii) subsequent reaction with sodium chloro acetate in alcohol-water mixture. The chelating agent in 2-ethylhexanol-cyclohexanol (1:1) solutions shows extremely high chelating ability for Ni(II) Co(II) Cu(II) Fe(111) Cr(III) and Cd(II) ions in neutral aqueous solutions. Extractions take place by the formation of (1:1) ligand-to-metal complexes and extraction coefficients are in the range 0.74-0.99. The ligand can be regenerated almost quantitatively by washing its complexes with 1M HCl and 0.2 M NaOH solutions successively. In each extraction step the organic solution exhibits a clear-cut phase separation and does not need salting out. The chelating agent can be regenerated and recycled more than 24 times without losing its extracting ability due to nonhydrolyzability of linkages in its structure. Experiments indicate that in high metal concentrations (more than 1 M) the solvent mixture itself is able to extract appreciable amounts of metal ions (33-53%). The solubility in organic solvents induced by long aliphatic chains seems to be general and the method presented offers possibility of large scale chelate extraction of metal ions of relatively low concentrations.
Citation Count: 12
Metalization of polymer beads via polymer-supported hydrazines as reducing agents
(John Wiley & Sons Inc, 2002) Bıçak, Niyazi; Şungur, Şana Kutun; Tan, Nükhet; Bensebaa, Farid; Deslandes, Yves
A new method for depositing metal onto a polymer surface has been developed in which the metal coating of polymer beads is performed with hydrazine functions as reducing agents on the surface of the polymer itself. In this study glycidyl methacrylate-methyl methaerylate-divinyl benzene terpolymer was prepared as spherical beads with a suspension polymerization methodology. Beads of the polymer sample (210-420-mum fraction) containing 3.4 mmol g(-1) epoxy were treated with an excess of hydrazinium hydroxide to yield a polymer with 2.3 mmol g(-1) hydrazine functions. The hydrazine functions on the polymer surfaces were efficient in metal reductions. Therefore the modified bead polymer samples when soaked in aqueous ammonia solutions of Ni(II) Ag(I) and Cu(II) ions (0.1 M) were covered rapidly by the corresponding zero-valent metal ions. Metal deposition took place almost quantitatively (ca. 4.5 mmol/g of the polymer) within 60 min of the contact times. The accumulations of metal were followed visually and occurred only on the polymer beads. There was no evidence that the reaction occurred within the solution. (C) 2002 Wiley Periodicals Inc.
Citation Count: 22
Selective liquid-liquid extraction of mercuric ions by octyl methane sulfonamide
(Marcel Dekker Inc, 2003) Bıçak, Niyazi; Sungur, Sana; Gazi, Mustafa; Tan, Nükhet
N-octyl methane sulfonamide (OMSA) has been demonstrated to be a very efficient reagent for selective extraction of Hg(II) ions from aqueous solutions. The extraction bases on rapid reaction of OMSA with Hg(II) ions yielding mono and disulfonamido mercury compounds in ordinary conditions. Solubility of OMSA and its mercury compounds in 2-ethyl hexanol provide a clear-cut phase separation in the extraction. The solution of OMSA in 2-ethyl hexanol (0.4 mol L-1) is able to extract 82.2% of mercuric-acetate (0.4 mol L-1) in non-buffered conditions. Although the process depends on the nature of accompanying anions the distribution coefficient is reasonably high (k(d) greater than or equal to 1.27) even in the presence of chloride ions. The extraction is strictly selective and the presence of Cd(II) Zn(II) Pb(II) do not bring any interference. The extraction system works in moderate concentrations. Extracted mercury in the organic phase can be recovered by back-extraction with concentrated HCl or H2SO4 solutions. After acid treatment the organic solution of OMSA becomes regenerated without losing its activity due to reasonable hydrolytic stability of the sulfonamide linkage and it can be recycled for further extractions.
Citation Count: 0
Chebyshev nets formed by Ricci curves in a 3-dimensional Weyl space
(Elsevier Science Bv, 2005) Yıldırım, Gülçin Çivi; Özdeğer, Abdülkadir
In this paper Ricci curves in a 3-dimensional Weyl space W-3(g T) are defined and it is shown that any 3-dimensional Chebyshev net formed by the three families of Ricci curves in a W-3(g T) having a definite metric and Ricci tensors is either a geodesic net or it consists of a geodesic subnet the members of which have vanishing second curvatures. In the case of in indefinite Ricci tensor only one of the members of the geodesic subnet under consideration has a vanishing second curvature. (c) 2004 Elsevier B.V. All rights reserved.
Citation Count: 7
On sectional curvatures of a Weyl manifold
(2006) Özdeğer, Abdülkadir
In this paper it is proved that if at each point of a Weyl manifold the sectional curvature is independent of the plane chosen then the Weyl manifold is locally conformal to an Einstein manifold and that the scalar curvature of the Weyl manifold is prolonged covariant constant.
Citation Count: 224
A fuzzy AHP approach to evaluating machine tool alternatives
(Springer, 2006) Ayağ, Zeki; Özdemir, Rifat Gürcan
Selecting process of a machine tool has been very important issue for companies for years because the improper selection of a machine tool might cause of many problems affecting negatively on productivity precision flexibility and company's responsive manufacturing capabilities. On the other hand selecting the best machine tool from its increasing number of existing alternatives in market are multiple-criteria decision making (MCDM) problem in the presence of many quantitative and qualitative attributes. Therefore in this paper an analytic hierarchy process (AHP) is used for machine tool selection problem due to the fact that it has been widely used in evaluating various kinds of MCDM problems in both academic researches and practices. However due to the vagueness and uncertainty on judgments of the decision-maker(s) the crisp pair wise comparison in the conventional AHP seems to insufficient and imprecise to capture the right judgments of decision-maker(s). That is why
Citation Count: 12
A combined fuzzy AHP-goal programming approach to assembly-line selection
(IOS Press, 2007) Ayağ, Zeki; Özdemir, Rıfat Gürcan
In mass production assembly-line balancing (ALB) problem has been a critical and repetitive issue for companies for long time. On the other hand equipment selection for stations has also been another important problem at the design stage of an assembly-line system. In this paper both problems are handled simultaneously. Therefore first goal programming (GP) method a well-suited technique is used to develop a preemptive formulation to joint both of the problems when the nature of the problem consists of several conflicting objectives and some mathematical constraints on solutions. Second an AHP method based on fuzzy scales which is incorporated with the GP is also used due to the fact that it takes both qualitative and quantitative judgments of decision-maker(s) into consideration to rank the equipment alternatives for stations by weight. The fuzzy AHP as one of the most commonly used multiple-criteria decision making (MCDM) methods has been effectively used for more than decade in both academic research and practice and takes the vagueness and uncertainty on judgments of decision-maker(s) into consideration due to the fact that the crisp pairwise comparison in the conventional AHP seems to insufficient and imprecise to capture the right judgments of decision-maker(s). In short in this study a combined fuzzy AHP-GP approach is proposed to evaluating assembly-line design alternatives with equipment selection. An integer GP formulation is constructed which also uses the fuzzy AHP scores of equipment alternatives and employs them as one of the goals. Then the mathematical model is solved to find out the ultimate alternative in terms of the minimized equipment cost and the maximized preference measures of decision-maker(s). The proposed approach is also illustrated on a sample case study.
Citation Count: 114
An intelligent approach to ERP software selection through fuzzy ANP
(Taylor & Francis, 2007) Ayağ, Zeki; Özdemir, Rıfat Gürcan
During the implementations of enterprise resource planning (ERP) systems most companies have experienced some problems one of which is how to determine the best ERP software satisfying their needs and expectations. Because improperly selected ERP software may have an impact on the time required and the costs and market share of a company selecting the best desirable ERP software has been the most critical problem for a long time. On the other hand selecting ERP software is a multiple-criteria decision-making (MCDM) problem and in the literature many methods have been introduced to evaluate this kind of problem one of which is the analytic hierarchy process (AHP) which has been widely used in MCDM selection problems. However in this paper we use a fuzzy extension of an analytic network process (ANP) a more general form of AHP which uses uncertain human preferences as input information in the decision-making process because the AHP cannot accommodate the variety of interactions dependencies and feedback between higher- and lower-level elements. Instead of using the classical eigenvector prioritization method in the AHP only employed in the prioritization stage of ANP a fuzzy-logic method providing more accuracy on judgements is applied. The resulting fuzzy ANP enhances the potential of the conventional ANP for dealing with imprecise and uncertain human comparison judgements. In short in this paper an intelligent approach to ERP software selection through a fuzzy ANP is proposed by taking into consideration quantitative and qualitative elements to evaluate ERP software alternatives.
Citation Count: 44
A hybrid approach to machine-tool selection through AHP and simulation
(Taylor & Francis, 2007) Ayağ, Zeki
The selection process of a machine tool has been a critical issue for companies for years because the improper selection of a machine tool might cause many problems having a negative effect on productivity precision flexibility and a company's responsive manufacturing capabilities. Therefore in this paper to determine the best machine tool satisfying the needs and expectations of a manufacturing organization among a set of possible alternatives in the market a hybrid approach is proposed which integrates an analytic hierarchy process (AHP) with simulation techniques. The AHP as one of the most commonly used multiple criteria decision-making methods is used to narrow down all possible machine tool alternatives in the market by eliminating those whose scores (or weights) are smaller than a determined value obtained under certain circumstances. Then a simulation generator is used first to automatically model a manufacturing organization where the ultimate machine tool will be used and second to try each alternative remaining from the AHP as a scenario on the generated model. Finally the final alternative is selected by using the unit investment cost ratio which is calculated by dividing the investment cost per year of each alternative by the additional number of produced units obtained from the simulation experiment of the relevant alternative.
Citation Count: 87
An analytic network process-based approach to concept evaluation in a new product development environment
(Taylor & Francis, 2007) Ayağ, Zeki; Özdemir, Rifat Gürcan
Selecting the best product concept is one of the most critical tasks in a new product development (NPD) environment. Making decisions at this stage becomes very difficult due to imprecise and uncertain product requirements. So the evaluation process of determining the most satisfying conceptual design has been a very vital issue for companies to survive in fast-growing markets for a long time. Therefore most companies have used various methods to successfully carry out this difficult and time-consuming process. Of these methods an analytic hierarchy process (AHP) has been widely used in multiple-criteria decision-making problems (i.e. concept selection equipment evaluation). In this study however we use an analytic network process (ANP) a more general form of AHP due to the fact that AHP cannot accommodate the variety of interactions dependencies and feedback between higher and lower level elements. Briefly in this paper an ANP-based approach is presented to evaluate a set of conceptual design alternatives in order to reach to the best concept satisfying the needs and expectations of both customers and company. In addition a numerical example is presented to illustrate the proposed approach.
Citation Count: 57
A memetic random-key genetic algorithm for a symmetric multi-objective traveling salesman problem
(Pergamon-Elsevier Science Ltd, 2008) Samanlıoğlu, Funda; Ferrell, William G., Jr.; Kurz, Mary E.
This paper proposes a methodology to find weakly Pareto optimal solutions to a symmetric multi-objective traveling salesman problem using a memetic random-key genetic algorithm that has been augmented by a 2-opt local search. The methodology uses a target-vector approach" in which the evaluation function is a weighted Tchebycheff metric with an ideal point and the local search is randomly guided by either a weighted sum of the objectives or a weighted Tchebycheff metric. The memetic algorithm has several advantages including the fact that the random keys representation ensures that feasible tours are maintained during the application of genetic operators. To illustrate the quality of the methodology, experiments are conducted using Euclidean TSP examples and a comparison is made to one example found in the literature. (C) 2008 Elsevier Ltd. All rights reserved.
Citation Count: 0
Optimization Model for Distributed Routing for Disaster Area Logistics
(IEEE, 2009) Samanlıoğlu, Funda; Ram, Bala; Bhadury, Joy; Stanfield, Paul; Davis, Lauren B.; Samanlıoğlu, Funda
The problem of transportation in a disaster area can be seen broadly as having two aspects: (a) moving people and materials out of an area and (b) moving people and materiel into the same area. The common thread here is the use of a limited set of surface and air transportation gateways into and out of the area. The distributed routing problem here is that of assigning one from among the limited set of gateways to various transportation requests in real-time while maximizing some measure of success for the entire relief mission. We define the general problem provide an example of the real-time transportation routing problem and propose an optimization model. The similarity of this problem to a job shop scheduling problem is presented pointing to the fact that a distributed approach based on bio-inspired methods can be developed to counter the large problem size and centralized nature of the integer multi-commodity network model. A small illustrative model of the integer multi-commodity network model is presented and solved
Citation Count: 136
A hybrid approach to concept selection through fuzzy analytic network process
(Pergamon-Elsevier Science Ltd, 2009) Ayağ, Zeki; Özdemir, Rıfat Gürcan
Evaluating conceptual design alternatives in a new product development (NPD) environment has been one of the most critical issues for many companies which try to survive in the fast-growing world markets. Therefore most companies have used various methods to successfully carry out this difficult and time-consuming evaluation process. Of these methods analytic hierarchy process (AHP) has been widely used in multiple-criteria decision-making (MCDM) problems. But in this study we used analytical network process (ANP) a more general form of AHP instead of AHP due to the fact that AHP cannot accommodate the variety of interactions dependencies and feedback between higher and lower level elements. Furthermore in some cases due to the vagueness and uncertainty on the judgments of a decision-maker the crisp pairwise comparison in the conventional ANP is insufficient and imprecise to capture the right judgments of the decision-maker. Therefore a fuzzy logic is introduced in the pairwise comparison of ANP to make up for this deficiency in the conventional ANP and is called as fuzzy ANP. In short in this paper a fuzzy ANP-based approach is proposed to evaluate a set of conceptual design alternatives developed in a NPD environment in order to reach to the best one satisfying both the needs and expectations of customers and the engineering specifications of company. In addition a numerical example is presented to illustrate the proposed approach. (C) 2008 Elsevier Ltd. All rights reserved.
Citation Count: 10
Radio frequency identification system optimisation models for lifecycle of a durable product
(Taylor & Francis Ltd, 2010) Samanlıoğlu, Funda; Ram, Bala; Stanfield, Paul; Samanlıoğlu, Funda; Davis, Lauren B.; Bhadury, Joy
We address the implementation of radio frequency identification (RFID) technology to support and manage durable products over their entire lifecycle with a focus on optimising the RFID tagging system. We develop general models that optimise the placement of RFID tags on an end product and its components the allocation of the data on tags and the selection of RFID tags and their configuration. The primary criteria for optimisation are to maximise the value of RFID data and to minimise the total cost of the RFID tag system. The total cost of RFID tags comprises costs associated with memory capacity tag type software acquisition and maintenance and number of tags used
Citation Count: 5
Conformal and generalized concircular mappings of Einstein-Weyl manifolds
(2010) Özdeğer, Abdülkadir
In this article after giving a necessary and sufficient condition for two Einstein-Weyl manifolds to be in conformal correspondence we prove that any conformal mapping between such manifolds is generalized concircular if and only if the covector field of the conformal mapping is locally a gradient. Using this fact we deduce that any conformal mapping between two isotropic Weyl manifolds is a generalized concircular mapping. Moreover it is shown that a generalized concircularly flat Weyl manifold is generalized concircular to an Einstein manifold and that its scalar curvature is prolonged covariant constant. © 2010 Wuhan Institute of Physics and Mathematics.
Citation Count: 3
Determining master schedule of surgical operations by integer programming: A case study
(Institute of Industrial Engineers, 2010) Samanlıoğlu, Funda; Ayağ, Zeki; Batili, Burcin; Evcimen, Esra; Yılmaz, Gulsah; Atalay, Ozlem
Fixed amounts of available Operating Room (OR) time compatibility of ORs and restrictions related to surgery equipment and surgeon availabilities complicate the process of preparing the master surgical schedule at hospitals. In this research an integer programming model and its application at Etiler World Eye Hospital (in Turkey) are presented in order to create a master surgical schedule that includes the most common surgery types on weekly basis and resolves surgeon equipment and operating room restriction and availability issues. The integer programming model utilizes the available OR time at the hospital by minimizing the total underallocation of OR time with respect to targeted OR time of surgeons taking into consideration surgeon equipment and OR restrictions and availabilities. The mathematical model is then solved using a commercial solver to obtain a weekly master surgical schedule for the hospital.
Citation Count: 15
A combined fuzzy AHP-simulation approach to CAD software selection
(Taylor & Francis Ltd, 2010) Ayağ, Zeki
In this paper a combined approach where the fuzzy analytic hierarchy process (AHP) and simulation come together is presented to select the best computer-aided design (CAD) software out of the available options in the market. The fuzzy AHP is used due to the vagueness and uncertainty of the judgements of a decision maker(s) because the crisp pair-wise comparison in the conventional AHP seems to be insufficient and imprecise to capture the right judgements of the decision maker(s). In this study first the fuzzy AHP is used to reduce a possible number of alternatives for the CAD system to an acceptable level for further study simulation analysis. Secondly a simulation generator as an integrated part of the fuzzy AHP is used to try the remaining alternatives on the generated model of a real-life product organisation in which the final alternative will be used. The results of simulation experiments are obtained and then evaluated to reach to the ultimate CAD alternative.
Citation Count: 3
Analytic Network Process (ANP) for solar power plant location problem
(Institute of Industrial Engineers, 2010) Samanlıoğlu, Funda; Ayağ, Zeki
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 Network Process (ANP) to figure out the most satisfying alternative. A numerical example is also included to show the proposed methodology in Turkey.
Citation Count: 39
Computing trade-offs in robust design: Perspectives of the mean squared error
(Pergamon-Elsevier Science Ltd, 2011) Samanlıoğlu, Funda; Samanlıoğlu, Funda; Cho, Byung Rae; Wiecek, Margaret M.
Researchers often identify robust design as one of the most effective engineering design methods for continuous quality improvement. When more than one quality characteristic is considered an important question is how to trade off robust design solutions. In this paper we consider a bi-objective robust design problem for which Pareto solutions of two quality characteristics need to be obtained. In practical robust design applications a second-order polynomial model is adequate to accommodate the curvature of process mean and variance functions thus mean-squared robust design models frequently used by many researchers would contain fourth-order terms. Consequently the associated Pareto frontier might be non-convex and supported and non-supported efficient solutions needs to be generated. So the objective of this paper is to develop a lexicographic weighted-Tchebycheff based bi-objective robust design model to generate the associated Pareto frontier. Our numerical example clearly shows the advantages of this model over frequently used weighted-sums model. (C) 2010 Elsevier Ltd. All rights reserved.

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