Endüstri Mühendisliği Bölümü Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/226

Browse

Now showing 1 - 8 of 8

An edge matching approach for two-dimensional irregular shaped cutting stock problems
(2012) Akbulut, Derya; Endüstri Mühendisliği
In this thesis, a two-dimensional irregular shape cutting stock problem is considered, in which a number of irregular shaped pieces are cut out of rectangular stock sheets so that waste of stock to be minimized. This is an operational problem commonly observed in metal cutting and textile industries. In the literature, there are many algorithms proposed to find optimal or suboptimal solutions for the problem. Since the problem is NP-hard, heuristic approaches predominate among the solution methodologies. In this study, a non-linear mixed integer mathematical model formulation is developed and it is tested for small sized problems. For larger scale problems, an edge matching approach is proposed to generate cutting patterns. The approach is based on positioning of the pieces in such a way that their most fitting edges are aligned together or to the borders. In this way, the total scrap and the cutting operations are minimized. On the contrary to the most of the solution methodologies in the literature, the method enables rotating pieces by any angle during the alignment process and further more it is applicable for irregular shaped stock materials. The developed procedure is tested against the traditional cutting stock approaches using benchmark test problems reported in the literature. It is found that our procedure outperforms for a large portion of these benchmark problems.
An employee transporting problem and its heuristic solutions
(2007) Önder, İlter; Endüstri Mühendisliği
A typical Vehicle Routing Problem (VRP) can be described as a problem of designing the least cost routes from one depot to a set of geographically scattered points. The VRP assumes that the vehicle capacities are identical, yet in real life the vehicle capacities are different. Therefore, this thesis presents a study of VRP with heterogeneous vehicles (HVRP). A lower bound on the cost of vehicles and routing is calculated for the HVRP using some mathematical models. Various heuristics are attempted to decide which one provides better solutions on the average. The better heuristic is selected based on the deviation from the lower bound. A simple software is prepared using the best heuristic methods for the employee pickup and delivery operations of a hypothetical company
An integration of Bayesian belief networks in multi-criteria decision analysis: An application in medical decision making
(2007) Karatepe, Dilan; Endüstri Mühendisliği
This thesis analyzes the Medical counseling problem regarding breast cancer disease by using Bayesian Belief Network structure to visualize the conditional dependencies between variables and their impact on each other. Analytical Hierarchy Process (AHP) method is utilized to approximate the conditional probabilities of the diagnostic Fine Needle Aspiration (FNA) test outcome. The accuracy of the results obtained from surgical biopsy are compared to the actual outcomes and evaluated in terms of consistency and error magnitude
Implementation of deterministic inventory models with backorders and lost sales in a retail company
(2018) Aygüneş, Haluk; Yıldız, gözde; Endüstri Mühendisliği
Bu tez kapsamında, elektronik ve bilgisayar malzemelerin perakende satışını yapan bir firmanın envanter yönetimi üzerine bir çalışma yapılmıştır. Sonradan karşılama ve satış kayıplarını içeren deterministtik envanter modelleri kullanılmıştır. Stoksuz kalma durumunda, bazı satışlar tamamen sonradan karşılanmakta, bazıları tamamen kayıp olmakta ve bazıları ise kısmen sonradan karşılanmakta ve kısmen kayıp olmaktadır. Bu durumların her biri en düşük maliyetli sipariş miktarlarını belirlemek amacıyla ayrı ayrı ele alınmıştır. Ayrıca, tedarikçilerin bazı ürünler için sunduğu miktar indirimleri de incelenmiştir.
Intermodal freight transportation in humanitarian logistics
(2016) Kavlak, Hasan; Endüstri Mühendisliği
Intermodal freight transportation is used heavily in commercial logistics around the world. On the other hand, in humanitarian logistics, it is not considered as the primary solution. Transportation resilience during response phase is an important performance criterion for humanitarian logistics and it mostly depends on the availability of the modes used for transporting relief items. Previous studies brought multi-modal or multi-vehicle transportation to forefront. Intermodal freight transportation is not focused from a perspective of resilience in humanitarian logistics. This study aims to highlight the differences between intermodal transportation and multi-modal transportation and to present a resilient transportation system without handling of relief items. Two integer programming models are developed based on a time-space network by considering route and vehicle availabilities changing dynamically over a specified time horizon. In these models, different types of vehicles and different capacities of unit loading device and intermodal transportation unit are considered, namely, truck (highway), freight train (railway), vessel (seaway), plane (airway) and helicopter (airway). This study proposes a unit loading device for humanitarian logistics that is compatible with different transportation modes. The first model includes an integer variable representation for vehicle fleets of different transportation modes. It can be concluded that the second model includes an index representation of individual vehicles for different transportation modes. The first mathematical model with integer variable representation of vehicle fleets is more effective than the second one. Five real life scenarios are fed into these mathematical models and the results are compared. The results of the experimental study show that intermodal transportation provides better humanitarian response in terms of resilience.
Scheduling in a three-stage dedicated hybrid flowshop with a common third-stage
(2008) Soysal, Serdar; Endüstri Mühendisliği
In this study, we consider a scheduling problem of a manufacturing environment in which there are two manufacturing flow lines, where the third stage of the first line and the second stage of the second line are common. Each stage in the first flow line has a single machine whereas the second flow line contains two identical parallel machines in its first stage. Type-1 jobs are processed in the first flow line, whereas second flow line is dedicated to type-2 jobs. The last operation, of both types of jobs, must be processed on a common machine. The problem is to determine the sequence and schedule of all jobs at all stages of the two flow lines so that the makespan is minimized. We develop a mathematical model and a branch-and-bound algorithm with lower and upper bounding procedures to find optimal solution; we propose heuristic algorithms which provide good quality solutions at little computational effort when the computational effort to obtain an exact solution is prohibitive. The effectiveness of our solution approaches are demonstrated by computational analyses.
Unrelated parallel machines scheduling under machine availability and eligibility constraints
(2012) Kurt, Atıl; Endüstri Mühendisliği
In the literature of the parallel machines scheduling, it is generally assumed that all machines are continuously available for processing jobs and each job can be processed by any machine. However, these assumptions become unrealistic in some industrial environments. In this study, we consider the problem of scheduling n independent jobs on m unrelated parallel machines subject to machine availability and eligibility constraints, given the maximum continuous working time before the maintenance of each machine and the maintenance time. Our objective is to minimize the makespan, which is the time to complete the processing of all jobs. We consider both resumable and non-resumable jobs, and develop mathematical models and heuristic algorithm that obtain exact and near-optimal solutions, respectively, for both cases with multiple machine unavailability periods. Computational experiments are done to evaluate the performance of our solution methods in terms of both quality and time. The results show that the proposed heuristic algorithm finds near-optimal solutions in very short time
Citation - WoS: 14
Citation - Scopus: 18
Using containers as astorage facilities in humanitarian logistics
(Emerald Group Publishing Ltd, 2014) Ertem, Mustafa Alp; Ertem, Mustafa Alp; Emur, Emel; Endüstri Mühendisliği
Purpose - The purpose of this paper is to investigate the use of freight containers to store relief items instead of operating a permanent warehouse building. Design/methodology/approach - A mathematical model is developed to determine the location and quantity of containers as well as the type and amount of relief supplies to store in order to investigate the practicality of using freight containers for storage. The model is tested using earthquake risk data, estimates of population under risk, and the distances between cities. An experimental study is performed using Turkish Prime Ministry Disaster and Emergency Management Presidency (abbreviated as AFAD in Turkish) data for total number of relief supplies. Findings - Considering the earthquake risk of possible locations, the results of the study indicate the target locations for containers. The idea of using containers as storage facilities helped beneficiaries to be reached within a short distance and in an efficient way. Research limitations/implications - The presented model is not implemented in real life disaster relief operations even if it is tested with real earthquake risk, demand and distance data. Practical implications - To apply this model in practice, the container locations within cities should be determined and managerial operations such as maintenance, environmental, and security planning have to be considered. Originality/value - This study presents the first analysis of three sub-topics' intersection: warehousing, pre-positioning in disaster relief, and containerization. To the best of authors' knowledge, containers have not been considered for storage of relief items in humanitarian logistics before.

Browse

Browsing Endüstri Mühendisliği Bölümü Tezleri by Author "Endüstri Mühendisliği"