Theses supervised by Bela Vizvari
11 theses · Eastern Mediterranean University
Reconstruction of World Bank Classification of Countries and Moody’s Rating System
This thesis has two main objectives. The first objective is to analyze whether the classification of countries provided by the World Bank (WB) can be reconstructed with a linear and/or integer-programming model known as Multi-Group Hierarchical Discrimination method, using only data published by the WB. The model’s parameters were determined for a collection of 44 countries, and the model was verified using another 39 countries. Moreover, the study examines the relative importance of factors in classification of countries. The second purpose of this study is applying Logical Analysis of Data for country risk rating to provide an approximate rating method. The employed data is available in World Bank and International Monetary Fund and the results are compared with Moody’s rating scale on year 2010. The country risk rating model was established for a collection of 71 countries, and the model was verified using another 34 countries. Furthermore, the study examines the relative importance of economical, environmental, educational, and infrastructure criteria in determining countries risk rating. Keywords: Multi-Group Hierarchical Discrimination, Classification of countries, Country Risk Rating, Logical Analysis of Data
Simultaneous Scheduling of Preventive Maintenance and Production for Single and Parallel Machines
In the last decades, the simultaneous scheduling of production and preventive maintenance has been receiving a considerable attention. Initially, in most researches, maintenance activities were treated as tasks with a fixed period. However, this assumption leads to create a hole in the time horizon. Recently, the variations in maintenance times were addressed, but the starting time is still fixed and known in advance in most of the works. There are few researches that consider the maintenance starting times as decision variables, especially in the non-preemptive case. In this study, the expected total completion time is minimized in the case of a single machine and random failures. The probability of machine failure is an increasing function of the age and the length of the time interval, and preventive maintenance reduces the machine age to zero. The problem is represented by a nonlinear integer programming model which is reduced later to an unconstrained 0-1 optimization problem. Subsequently, a method for solving the unconstrained model by identifying the preventive maintenance decisions is proposed. Moreover, the problem for minimizing the expected makespan on the single machine for the same above mentioned maintenance conditions is addressed and two heuristics methods were proposed to solve the problem. Additionally, the problem of parallel machines which are under the same reliability conditions, but they may have different values of maintenance parameters is discussed. An approximation method based on the bin packing‟s first fit algorithm as well as an exact branch and bound method were introduced to solve the problem. Finally, numerical examples were provided to illustrate each solution procedure of the proposed methods and some analysis was performed. The results show the benefits of integrating both decisions of production and maintenance, because some savings in the values of the discussed performance measures were obtained.
Cyclic Production of Flexible Manufacturing Cells
This thesis deals with two different flexible manufacturing cells. Both cells contain m identical computer numerical control (CNC) machines that are able to perform all the processes to produce a final product. The CNC machines are set up in a line layout. In the both cases, one input station and one output station exists at the beginning and at the end of the line, respectively. The items to be processed are kept in the input station, and the finished items are kept in the output station. In the second case, in addition to the input station, there is an individual input buffers attached to each machine. Using these buffers, each machine can be consecutively loaded twice in a cycle. In the both cells, a robot serves the machines and transports parts from the input station to a machine, loads the machine, and unloads the machine, after finishing its process, and puts the processed part in the output station. In these cells, m different parts will be processed in every cycle. Each part is processed completely by one machine. If the system is at a specific state at the beginning of a cycle, it reaches the same state at the end of the cycle, and then repeats the same actions in the same order in the subsequent cycles. To show all of the possible cycles in such cells, a sequential part production matrix is presented considering a general case. The duration of a cycle is called cycle time. The objective function of both cell types is to find the order of robot operations that minimizes the cycle time which maximizes the long-run average throughput rate of each cell. For the first case, a new mathematical model is presented to optimize the system. A reduced version of the new model is also provided. The reduced version is still an exact model of the minimization of the cycle time, however it does not determine the waiting times of the robot directly. These two models are more effective than the previous existed exact models in the literature. The solution of the reduced model requires significantly less CPU time comparing to the other models. A metaheuristic algorithm based on simulated annealing algorithm is proposed. In order to compute the minimum cycle time in each iteration of the algorithm, a linear programming model is needed to be solved which is the first case in the literature to the best of our knowledge. A new proof is provided for the lower bound of cycle time. This new proof facilitates the optimality analysis of several sequences of the robot movements. For the second case, a mathematical model is presented to optimize the cyclic production. A two-machine cell is discussed in details. In addition to some lower bounds of the cycle time for different orders of robot movements, the optimal cycles and upper bounds for the cases with different activities are also investigated.
Investigating Gap between Customers’ Taste and Market Variety and its Impact on the Customer Satisfaction: An Empirical Study in the Automotive Industry
This study investigates and examines the gap between customer preferences and market variety in the Iranian automobile market and its impacts on customer satisfaction. A linear approximation is used for the utility function of customers of the Iranian carmaker (Iran Khodro Co). Also the SERVQUAL model for measuring customer satisfaction is used to determine, the gap between customer expectation and perceived quality. The moderator variable called “Role of car in the customer life” is introduced and its effect on the relationships between customer expectation, perceived quality and customer satisfaction is evaluated. The results show that considering the history of car sales over the past five years compared with the value predicted by the existing car market share, a significant gap between the current sales of IKCO and a product assortment ideally adapted to the customers is detected. The highest gap occurred between the level of expectation and the perceived quality of factors, respectively belonging to sale, car accessories, technical and physical aspects and the after-sale services. In this way, companies can elaborate better strategies and production plans and can increase their market share. As a contribution, this study provides a method for identifying customer behavior based on choices among options consisting of a set of qualitative and quantitative factors. So the method presented in this study can be used to empower automakers corporations to increase their competitive advantage and create the readiness to enter and compete in global market. This could prevent decline in automakers share and increase their profitability through achieving customer satisfaction. We live in a dynamic and changing environment. Changes in customer tastes and purchasing power; Changes in technical standards specifically regulations related to polluting potential of cars and tariff regulations; Changes in market structure toward openness to global market and increasing competition, could reduce the applicability of this research results. So these are open questions for future researches. Also as a topic for further research, the number of vehicles and factors types can be changed to evaluate the market share. Also, the effect of the moderator variable on customer satisfaction for other useable products and services may be investigated.Öz:Bu çalışma İran otomobil piyasasındaki müşteri tercihleri ve pazar çeşitliliği arasındaki boluğu ve bunun müşteri memnuniyeti üzerindeki etkisini araştırmakta ve incelemektedir. İranlı otomobil üreticisi (İran Khodro Co) müşterilerinin yarar fonksiyonu için doğrusal bir yaklaşım kullanılmıştır. Ayrıca müşteri beklenti ve algılanan kalite arasındaki boşluğu belirlemek ve müşteri memnuniyetini ölçmek için SERVQUAL modeli kullanılmıştır. "Müşteri hayatında arabanın rolü" adlı moderatör değişken olarak tanıtılarak müşterinin beklentisi, kalite algısı ve müşteri memnuniyeti üzerindeki etkisi değerlendirilmiştir. Sonuçlar, son beş yıl içerisindeki otomobil satışlarıyla mevcut araç pazar payı içerisindeki değeri karşılaştırıldığında, IKCO’nun mevcut satış ve ideal müşterilerine uyarlanmış bir ürün yelpazesi arasında anlamlı bir fark tespit edilmiştir. En büyük fark, satış, araba aksesuarları, teknik be fiziksel donanım ve satış sonrası hizmetlerin beklenti düzeyi ve kalite faktör algıları arasında meydana gelmiştir. Bu şekilde, şirketler daha iyi strateji ve üretim planlarını hazırlayarakmak pazar paylarını artırabileceklerdir. İleri bir araştırma konusu olarak, araç ve faktör türlerinin sayısı değiştirilerek pazar payı değerlendirilmesi önerilmektedir. Ayrıca, diğer kullanışlı ürün ve hizmetler için müşteri memnuniyeti moderatör değişkenin etkisi araştırılabilir.
Minimization of Emergency Response Time by Incorporating Aerial Transportation
In this thesis, we deal with two different real-life medical emergency service problems. In these problems, we consider a city in which the locations of all the hospitals, medical service centers, and the other emergency care centers are known. In both problems the emergency services are deployed using aerial and ground vehicles for moving towards patients in their locations after receiving a call, performing the initial emergency medical care, and transporting the patients to the hospitals or other medical care facilities. For this reason, the accidents or demands are classified into two types the severity accidents which need aerial vehicles and normal accidents which are operated by ground vehicles. According to the average number of the accidents in each location (node) and the severity of the accident, a weight is assigned to each node. In the first problem, we assume that the ground emergency services are optimal and we just deal with assigning a given number of the aerial vehicles to the hospitals or the medical care centers for the severity accidents or emergency medical demands in a way that the total response time by the aerial vehicles is minimized. In another words, this type of the demands for ground and aerial services are different in this type of the problem. In the second problem, we are dealing with both ground and aerial medical services together and at the same time. As the number of the accidents or the demands for both ground and aerial services are known and separate. In this type of the problem we are aiming to assign a given number of the aerial and ground vehicles to the hospitals or the medical care centers in a way that the total response time by all the aerial and ground vehicles is minimized.
Quality in Engineering Based on Feedback
Quality in production these days is a very important subject for all manufactures. Several researches mention customer’s dissatisfaction with quality of products they buy. Quality experts concentrate on the relations between quality and products, for example the relation between quality and price, between quality and market share, generally speaking, quality improvement projects may lead to higher or lower total profits?. This study has two main chapters; first chapter shows a project about quality problem for window lifter part of car in IKCO (Iran Khodro Company) which explains what are the steps for solving a quality problem in a specified factory (car producer factory) based on feedback. Following chapters explain a structure of quality improvement process that can be used for any kind of quality improvement project. It also deals with quality problem in any kind of factory. Keywords: Quality, window lifter, IKCO, questionnaire forms, action plan, side effects, project team, feedback, feasibility studying
Continuous Approach for the Transportation of Relief Items in Post-disaster Period of Large Scale Earthquakes
In the past decade, the use of an unmanned aerial vehicle (UAV) or drone which was mostly used in the military has been increased. They came up with this idea as an alternative to use the (UAV) transportation system instead of the usual package delivery (road transportation with trucks) also, as an additional tool (consider the truck as a station for UAV) for packages allocations in order to speed up the whole procedure. In this dissertation we extended and implemented the hybrid routing model by determining launching point and retrieve point subsequently for all these modification effect on operation time, consequently, in our own case, which is humanitarian logistics, it can rescue and save more people's lives. Keywords: traveling salesman problem, transportation problem, truck- UAV, post disaster response, large scale earthquake and humanitarian logistic
Comparative and Systematic Analysis of Disaster Management System
ABSTRACT: This study reviews, compares, and analyzes the legislative and institutional frameworks of the Disaster Management (DM) in Nigeria and India. This research aims to study the effectiveness and efficacy of the DM systems in both countries to identify the strengths and weaknesses and make recommendations for enhancing the current systems. The study initially provides a comprehensive introduction of Indian and Nigerian DM systems, including the countries’ disaster profiles and the current DM policies and institutional frameworks, then compares them from various perspectives to identify the similarities, differences, common challenges, and lessons learned. An intense documentary survey of relevant literature is applied in this study to obtain data and information. The study finds that India, by developing better legal and institutional frameworks, creates a more effective DM system than Nigeria in terms of the integration and prioritization of Disaster Risk Reduction (DRR) activities, community participation, and coordination and collaboration mechanisms. The research also discovers that both nations struggle to mobilize, manage, and utilize DM funds due to a lack of transparency in funding sources. The findings also show that both countries’ DM systems are mainly focused on natural disasters, with little emphasis provided on effective preventative and regulatory measures to handle man-made disasters. The study concludes that due to administrative and financial issues, none of the two countries achieved total success in capacity building activities. Keywords: Indian Disaster Management, Nigerian Disaster Management, Man-Made Disaster Management, Natural Disaster Management, Disaster Risk Reduction.
The Impacts of Economic Sanctions on Supply Chain Management
Over the last two decades, supply chains have shown a great tendency of expanding their networks beyond the national boundaries and using the global sourcing strategy. As a result, supply chains have become more complex and dynamic networks that extend over several countries, including multiple tiers of suppliers, each of which may have various entities with different operations, structures and goals. In this situation, any uncertainty in the political and economic relations between countries should be considered as a source of risks. After the rise of unforeseeable political issues, one conceivable response of nations is imposing sanctions which lead to significant problems in seller-buyer relationships. This study has focused on the Iranian supply chains -which have been suffering from harsh economic and financial sanctions in the recent years- in order to investigate the impact of such sanctions on supply chain risk management (SCRM). After identifying the most significant supply chain risks associated with different flows, namely material, information and financial flows, the identified risks are analyzed via a qualitative method with respect to means of probability, impact and effect of sanctions. The impact of sanctions on different risk drivers, industries and supply chain performance measures are investigated. The results show that sanctions have the greatest negative impact on financial risks compared to the other risk drivers and all companies regardless of their industries and scopes are found to be vulnerable to sanctions. As to performance criteria however, the analyses disclose that supply chain cost and cash to cash cycle should receive more attention whenever the supply chain are influenced by sanctions. The analyses reveal that supply chain risk factors are really triggered by sanctions specifically risks of exchange rate movements, material price fluctuations, supplier bankruptcy, inability to collect all receivables and buying from a single source which should be viewed as the leading risk factor in the presence of sanctions. In the final stage, the high ranked risks are discussed and appropriate risk management strategies are proposed to deal with them. Keywords: Supply chain management, Sanctions, Risk management.
How to Organize Society in a Refugee Camp?
ABSTRACT: As obligatory immigrant is the outcome of the world’s conflicts, displaced population from all unstable regions of world. They stay in camps in long periods and need ‘durable solutions’ according to their geographic and technical conditions for decades. Prolonged dislocation consequences from procedures in the local and global level. This prolonged condition leads to outcomes that backfire each of these levels, as well as insecurity, over consumption of already limited assets, and tense interstate relations. While immigrants stay in more and more protracted time, circumstances that formerly are impermanent seem to be permanence. Forced displacement all over the world increasingly change to be more in durable life circumstances, expressing different human impacts of conflict and power fights. By using a qualitative method in various sides of refugee camps, this study connects theory of self-government; social life constructs and work distribution to discover the possible motivation for creating refugee sites durable. House to approximately 2.6 million refugees, camps provide as a microcosm with various and multi-level humanitarian supports and refugee hosting actions. With analyzing data collected from UNHCR (United Nations High Commissioner for Refugees) documents, related articles, media resources and NGO (Non-Governmental Organization) reports, this research connects the recreation of state self-government, with features of social construction at the local phase that contribute to prolonged dislocation. Analyses of this data present planned and unplanned factors coming from foreign and local actors, NGO disaster and humanitarian aid principles, as well as refugees’ own iv opinion of residency, identity, and belonging that leads to contribute to the permanence refugee displacement. During all these procedures, this study starts on to describe a theory about the approach of hosting refugees and the way that refugees see themselves, and what leads to a form of immigration that turn into more and more long-term. Keywords: durable solution, prolonged refugee camp, society of refugee camp, refugee camp design.
Assignment of Patients to Hospitals in a Case of a Large-Scale Earthquake
The main topic of this thesis is the transportation of injured persons to the hospitals after a large-scale disaster. The main tool for solving the problem is machine scheduling. Machine scheduling in production planning activities of enterprises is a frequent activity in short-term planning and it is very important to use resources efficiently. The scheduling of identical parallel machines is adapted to the humanitarian logistics problem. List scheduling method is applied for makespan minimization. The results show comparisons of the shortest processing time (SPT) and longest processing time (LPT) rules to get the optimum sequence for the addressed problem by an algorithm. For the heuristic method; single vehicle, 2 vehicles and 3 vehicles cases are discussed. First of all, both demographic and geographic information have provided about Istanbul. It is assumed that in a case of a large-scale earthquake in İstanbul, the city is divided into regions by Voronoi diagram. The strategy is to dispatch him/her to the closest hospital according to location of the victim. The objective function of the study is to maximize the number of seriously injured people in post-disaster period by a proper assignment of existing ambulances to patients and the expected value of service level at the same time. The service level increases as the expected travel distance of patients decreases having inverse relation. Keywords: Humanitarian logistics, Earthquake, Disaster management, List scheduling, Heuristic method.