Endüstri Mühendisliği

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Theory and applications of a nonconvex programming algorithm
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1977., 1977.) Gürman, Erdoğan.; Ulusoy, Gündüz.
In this thesis, a solution technique to solve a class of nonlinear programming problems is presented. The problem considered is the minimization of separable concave functions and linear functions over linear polyhedra. A branch-and-bound algorithm for identifying an optimal solution is described; it is equivalent to the solution of a finite sequence of linear programming problems. Computational results are cited fbr a computer code developed implementihg the algorithm. The algorithm is applied to dynamic capacity expansion problem considering single plant-singie commodity, multi-plant-single commodity, and multi-plant-multi commodity cases.
Taşıt güzergahi belirleme problemleri ve bazı yeni algoritmalar
(Thesis (Assoc. Prof.) - Bogazici University. Institute of Sciences and Engineering, 1981., 1981.) Ulusoy, Gündüz.
A dynamic simulation model for urban mass transportation systems
(Thesis (M.S.)-Bogazici University. Faculty of Engineering, 1981., 1981.) Ünal, Adnan.; Or, İlhan.
A survey of assembly line balancing algorithms and a proposed algorithm
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Karayalçın, Alpaslan.; Evranuz, Çetin.
An adaptive and iterative approach to dynamic modelling of bicriterion optimization in power systems expansion decisions
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Özmızrak, Nur.; Kavrakoğlu, İbrahim.
In this study,power systems expansion decisions are modelled, using Bicriterion Linear Programing techniques. The model consists of: energy and power demand forecasts, production capacity, build-up rate, nuclear, hyifro (both base and peak), fossil and fuel energy constraints in an adaptive process of 5-yr. increments for a 25-yr. planning horizon. The model, as applied to the Turkish Power System, contains 40 decision variables and 45 constraints. Efficient (nondominated) solutions are obtained at each iteration with respect to the economic cost objective and one of the following objectives: pollution, space occupied or risk involved. The aim of this study is to derive a framework for the power systems expansion decisions based on trade-off functions between pairs of objectives. A particular combination of objective functions and changes in some parameters result in different scenarios. A fast algorithm develpped by Kızıltan [ 8], is adapted and used as a subroutine in order to obtain the preliminary solutions to the problem. According to the adaptive nature of the study, the overall solutions are grouped together to form decision alternatives and to show the trade-offs between the objectives. Special effort was expended on the generation of the computer programs so that minimum handling of data for a particular scenario is achieved together with a self explanatory output design.
Solution procedures for some multiobjective network problems
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Menlioğlu, A. Tarık.; Ulusoy, Gündüz.
In this thesis, solution procedures for mUltiobjective linear network problems and bicriteria fixed charge network problems are presented. A labeling algorithm for multobjective linear network simplex method is developed by incorporating a method of multiobjective LP and extended to the case with lower and upper bounds on the arc flows. A branch and bbund algorithm is given for the bicriteria fixed charge problem in order to generate the efficient extreme points.
Multiobjective linear programming and multiobjective zero-one programming
(Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Kızıltan, Gülseren.; Kavrakoğlu, İbrahim.
Multiproduct, multifacility, multiperiod deterministic production planning
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) İnal, Canan.; Erden, Selçuk.
Multi-item inventory control with joint set-up cost
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Vardar, Belkin (İlhan).; Evranuz, Çetin.
In this study, a multi-item inventory control system fora firm where groups of items are supplied by their own specific factories, was developed. The dependence between items is caused by the set-up cost structure: When several items are ordered on the same order list, a fixed set-up cost, independent of-the number of items and quantities, is incurred. In order to use this fixed part of the ordering cost, a joint ordering policy, the (s,c,S), was recommended for the inventory system. As stated by this policy, ordering decisions are taken also for items with inventories -below, their can-order points (ci 'S) when any item with an inventory below its must-order point s is ordered. A model with a monetary objective function minimizing the sum of ordering and inventory carrying costs and satisfying service level constraints, was set-up. An optimization algori thm, which is, a combination of mathematical optimization and simulation was used to ,determine optimal inventory control parameters (must order points, can-order points, and order-up-to levels). The solution algorithm was programmed and, its implementation for a selected group of items was presented in the study. The cost saving achieved by the dependent policy over a usual, independent inventory control system was also; demonstrated. Finally, the algorithm's performance under changes in the uncontrollable system parameters was analyzed and a case where changes occur indemand figures was presented at the end of the study.
A study on the optimization of switching networks
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Mısırlı, Çiğdem.; Evranuz, Çetin.
The aim in switching network optimization problem is to obtain optimal link capacities so that the resulting network cost is minimized and a certain satisfactory level of service is supplied to the subscrihers. Since the problem has a large size and encompasses nonlinearities, approximate solutions suffice. In the present study, the optimization problem, its characteristics, and related teletraffic concepts are presented. A solution procedure is developed by considering the existing approaches and is applied to some small scale example networks to show its functioning and to set a comparison basis for future study.
Optimization of warehouse setting and cotton textile supplying policy of Sümerbank in Marmara region
(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Yanık, İsmail.; Evranuz, Çetin.
This thesis presents a mixed integer programming model, designed for the analysis of various planning problems associated with the optimal setting of warehouse capacities and transportation of the cotton textile products among the Sumerbank system composed of factories, district warehouses and retail shops. The model has been nuerically tested by the relevant data taken from Sfunerbank Purch'asing and Marketing Organization (Alım Satım Muessesesi, ASM) concerning ten cotton textile factories and five district warehouses with three or four capadity alternatives placed in Marmara Region. The effects caused by the variations in the demand and stock-turnover rates are observed and reported in a comparative basis.
Level of competitiveness: |a case in Turkish textile industry
(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Akban, Ayfer.; Oral, Muhittin.
This study investigates the nature and degree of competitiveness in Turkish Textile Industry. An industrial survey has been conducted among twelve firms employing a questionnaire due to Oral. Based on the results of the survey, a mathematical model developed by Oral has been implemented to evaluate the level of competitiveness in the Industry. The model investigates the qualitative and quantitative variables which influence level of competitiveness, groups them, defines these groups as factors, studies the interaction of the factors and formulates level of competitiveness as a function of the relevant factors. Level of competitiveness is then computed under different scenarios and influence df basic factors on level of competitiveness is investigated through a parametric analysis. Consequently, goals for long term planning, which may be of help to improve level of competitiveness on sectorial basis have been defined.
Optimal control of M/M/S queueing systems
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Özekici (Müceldili), Nurizer.; Kaylan, Ali Rıza.
This thesis characterizes the optimal operating policy of multi-server queueing system subject to Poisson arrival process and exponentially distributed service times (M/M/S queue). Optimal policy minimizes the long-run total expected discounted cost to the system. The cost components 9f the system are taken as the server cost and the holding cost which is considered as the lost profit from the business or the lost production with respect to the type of the system. Markov Decision Theory is used in the characterization of the controlled process. Generator is the basic tool of the formulation. Application of some solution procedures is very easy for this type of formulation. Two different algorithms are presented to obtain the optimal policy: Successive approximation algorithm and policy improvement algorithm. Optimal policy for a simple maintenance problem is found using these two methods. Computational experiments on the computer indicate that the policy improvement method converges to the optimal policy more quickly. The theoretic results are extended to tandem queueing systems at the end.
The performance of the SPT-T rule on a multiproduct, multifacility production system
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Şahin, Orhan.; Oral, Muhittin.
This thesis presents a payment scheduling problem with bonus and penalty where both the client and the contractor are considered. In the study, an equitable solution is sought to determine the amount and timing of the payments. The equitable solution is defined as one where both the contractor and the client deviate from their respective ideal solutions by an equal percentage. The unit bonus and penalty are taken as constant percentages of the total payment with respect to the completion of the project under a given deadline. The bonus earned by the early completion is shared between two parties. However, the whole penalty is incurred by the contractor. Since the bonus and the penalty have an effect in the same direction on the project schedule, the bonus and the penalty cases are considered separately. In this thesis, a double genetic algorithm is employed, where the outer loop reveals a payment distribution, and the inner loop determines the timing of the activities and the payments so as to achieve maximum NPV for the contractor under a given payment distribution. The proposed GA is evaluated using a set
Application of planned-replacement policy in a copper-wire drawing company
(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Tan, Ömer Kudret.; Kaylan, Ali Rıza.
Optimal planning of transmission facilities for telecommunications networks
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1983., 1983.) Miraboğlu, Mehlika.; Evranuz, Çetin.
Maintenance planning in power systems operation
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1983., 1983.) Günyaşar, Varol.; Kavrakoğlu, İbrahim.
Determination of stand-by requirements in telecommunications networks
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1983., 1983.) Kaptanoğlu, Dilek.; Evranuz, Çetin.
To be able to give the required service to telephone customers in case of failures, one of the proposed protection measures is the use of stand-by circuits. Failures are defined as the breakdowns of transmission media. The stand-by protection problem can be solved in two steps. In the thesis, the first step, which is the determination of stand-by requirements is studied. Methodologies utilized in the calculation of blocking probabilities for obtaining the traffics carried by each route and a simplified heuristic approach called the "equivalent trunk group approach" which is utilized to determine the stand-by requirements are presented. Different mathematical formulations of the problem are given and some special cases are discussed. A solution·procedure is developed and applied to a small test network.
The bottleneck routing of military cargo aircraft
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1983., 1983.) Kasaroğlu, Murat.; Ulusoy, Gündüz.
The objective of this study is to develop an efficient method of routing military cargo planes in war time. A model with a nonlinear objective function is developed to determine these routes which minimizes the maximum mission time of planes. Based on this model, a solution procedure is introduced. Then, a heuristic procedure is suggeited to handle various airport capacity constraints. As an extension of the study, a proposal is made on a'model which minimizes the total mission of the planes. Consequently a study is made on the behaviour of the model on some special cases.
Four heuristic solution procedures to the travelling salesman problem and an application to the multi-depot vehicle routing problem
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1983., 1983.) Tovya, Yasef.; Ulusoy, Gündüz.
This study consists of two parts. In the first part, four heuristic algorithms for solving the Travelling Salesman Problem (TSP) is developed. Given a graph, the first algorithm forms a subgraph in which the necessary conditions for the existence of a travelling salesman tour are satisfied. In case the subgraph does not contain any travelling salesman tour, Little's bcanch and bound algorithm is partially applied to the resultant cost matrix. The second algorithm, starts with the minimum cost assignment and ranks the assignment solutions in ascending costs by introducing subtour breaking constraints. The third algorithm produces some best achievable n-paths which start from a root node and end at some node incident to the root node. These paths are then completed to travelling salesman tours and the least cost tour is taken as the best achievable solution. A geometric approach to solving the TSP is described in the last algorithm. Starting with a partial tour, the algorithm determines which of the remaining nodes are to be inserted between which consecutive pair of nodes on the subtour and in what order. After all, a summary of computational results regarding both the efficiency and the computational effort of all the algorithms is presented.

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