Most of today's optimization efforts aim to reduce costs, time or the number of resources used. H... more Most of today's optimization efforts aim to reduce costs, time or the number of resources used. However, optimization efforts should consider other factors as important as these, such as facilitating the lives of the disabled, elderly and pregnant and helping them in their daily lives. In this study, the Nuh Naci Yazgan (NNY) University (Kayseri/Turkey) personnel transport problems were discussed. The NNY University provides a shuttle service to bring employees to school at the start of the work and to leave them at home after work. In order to shorten the collection / distribution time and the total distance travelled, the service vehicle does not leave / pick up all employees in front of their homes. Instead, the employees are picked up / dropped at appropriate locations on an intuitively determined route. Since only the time and cost savings are taken into account when determining the service route, some employees have a long walking distance to the service route. This creates a very important problem, especially for the disabled and pregnant workers. In this study, a new mathematical model is proposed which takes into consideration the physical disadvantages and occupational positions of the employees in order to determine the shortest vehicle route. The results show that the proposed model can significantly reduce walking distances of physically disabled people without compromising the total distance travelled by the vehicle.
Journal of Applied Research on Industrial Engineering, 2020
Bed production has an important market in the furniture sector. In spite of the fact that sponge ... more Bed production has an important market in the furniture sector. In spite of the fact that sponge is generally preferred as filler in the production process of beds, increasing prices in recent years and the preference of new materials with the development of alternative filling materials have increased. Recently it is seen other than sponge, the granule, wadding, and STW are also used as filling material in bed production. From the management point of view, the choice of filler is an important decision problem that depends on the situation of the business and many objective and subjective criteria must be taken into consideration. It is appropriate to examine such a problem with the Analytical Hierarchy Method (AHP) and the ELECTRE method, which have the ability to make quantitative evaluations and synthesize factor weights from subjective judgments. The criteria for selection of the filler material and the extent to which the criterion will affect the evaluation are important decision points. The opinions of experts in bed production were consulted to determine the criteria to be used in the evaluation. The obtained results show that four basic criteria must be taken into consideration in the selection of filler material. In this study, AHP was used for determining the criteria weights, and ELECTRE methods were used for the selection of the best filling material. The results showed that wadding is the optimum filler material for bed production.
Purpose -The purpose of this paper is to examine the effectiveness of the multivariable grey pred... more Purpose -The purpose of this paper is to examine the effectiveness of the multivariable grey prediction model in deformation forecasting. Design/methodology/approach -Deformation in a dam can be seen because of many factors but without any doubt, the most influential factor is the water level. In this study, the deformation level of a point in the Keban Dam crest has been tried to be forecasted depending on the water level by the multivariable grey model GM(1,N). Regression analysis was used to test the accuracy of the prediction results obtained using the grey prediction model. Findings -The results show that there is a great consistency between the grey prediction values and the actual values, and that the GM(1,N) produces more reliable results than the regression analysis. Based on the results, it can be concluded that the GM(1,N) is a very reliable estimation model for limited data conditions. Originality/value -Different from the other studies in the literature, this study investigates deformation in a dam subject to the water level in the dam reservoir. The main contribution of the study to the literature is to suggest a relatively new procedure for estimating the deformation in the dams based on the water level.
Grey theory is one of the methods used to study uncertainty. The uncertain systems characterized ... more Grey theory is one of the methods used to study uncertainty. The uncertain systems characterized by small sample and poor information are the study object of grey system theory. Multivariable grey prediction models are part of grey forecasting system. They are presented if there are mutual relations among the factors in the system. They believe that all the influencing factors are not independent of each other and should be regarded as a whole. In multivariable grey forecasting models, the future value of a variable is tried to be forecasted considering the other influential factors in the system. In this study, deformation consisting on the crest of a Dam is aimed to determine by using multivariable grey prediction models. Özet Gri teori, belirsizliği incelemek için kullanılan yöntemlerden biridir. Sınırlı bilgi ve küçük örnekler ile karakterize edilmiş belirsiz sistemler, gri sistem teorisinin inceleme konusudur. Çok değişkenli gri tahmin modelleri gri tahmin sisteminin parçasıdır. Sistemdeki faktörler arasında karşılıklı ilişkiler varsa onlar temsil edilirler. Etkileyen faktörler birbirinden bağımsız değildir ve bir bütün olarak kabul edilmektedir. Çok değişkenli gri tahmin modeli, bir değişkenin gelecek değerini sistemdeki diğer etkilenen faktörleri göz önüne alarak tahmin etmeye çalışmaktadır. Bu çalışmada, çok değişkenli gri tahmin modeli kullanarak bir barajın kreti üzerinde oluşan deformasyonların tahmin edilmesi amaçlanmıştır.
Purpose-The purpose of this paper is to examine the effectiveness of the multivariable grey predi... more Purpose-The purpose of this paper is to examine the effectiveness of the multivariable grey prediction model in deformation forecasting. Design/methodology/approach-Deformation in a dam can be seen because of many factors but without any doubt, the most influential factor is the water level. In this study, the deformation level of a point in the Keban Dam crest has been tried to be forecasted depending on the water level by the multivariable grey model GM(1,N). Regression analysis was used to test the accuracy of the prediction results obtained using the grey prediction model. Findings-The results show that there is a great consistency between the grey prediction values and the actual values, and that the GM(1,N) produces more reliable results than the regression analysis. Based on the results, it can be concluded that the GM(1,N) is a very reliable estimation model for limited data conditions. Originality/value-Different from the other studies in the literature, this study investigates deformation in a dam subject to the water level in the dam reservoir. The main contribution of the study to the literature is to suggest a relatively new procedure for estimating the deformation in the dams based on the water level.
Purpose-The purpose of this paper is to present a mixed integer programming model for simple asse... more Purpose-The purpose of this paper is to present a mixed integer programming model for simple assembly line balancing problems (SALBP) with Type 1 when the annual demand and task durations are uncertain and encoded with grey numbers. Design/methodology/approach-Grey theory and grey numbers are used for illustrating the uncertainty of parameters in an SALBP, where the objective is to minimize the total number of workstations. The paper proposes a 0-1 mathematical model for SALBP of Type 1 with grey demand and grey task durations. Findings-The uncertainty of the demand and task durations are encoded with grey numbers and a well-known 0-1 mathematical model for SALBP of Type 1 is modified to find the minimum number of workstations in order to meet both the lower and upper bounds of the uncertain demand. The results obtained from the proposed mathematical model show a task-workstation assignment that does not distribute precedence relations among tasks and workstations and the sum of task durations in each single workstation is less than or equal to the grey cycle time. Originality/value-The grey theory and grey numbers have not been previously used to identify uncertainties in assembly line balancing problems. Therefore, this study provides an important contribution to the literature.
Project scheduling has been still one of the hottest topics in the management area. The goal of t... more Project scheduling has been still one of the hottest topics in the management area. The goal of traditional project management is to complete the project at the earliest possible time in accordance with the available resources without violating priority relations of the activities involved. Unlike traditional project management, this study deals with the possibility of a coalition among the staff available to accomplish tasks of the project. The tasks can be fulfilled by more than one staff members. Staff’s coalition shortens the completion time of the tasks. A natural problem that arises in this case is how to share the income generated. The other side of the problem is concerned with the project owner who wants the project to be completed as early as possible. In this study, a mathematical model proposal is dealt with in order to real-ize the goals of both the project owner and the staffs as much as possible within the complex structure of the situation.
Motivated by the increasing civilian use of Unmanned Aerial Vehicles (UAVs), this paper considers... more Motivated by the increasing civilian use of Unmanned Aerial Vehicles (UAVs), this paper considers the simultaneous location and routing of UAVs for multiple missions and different weather conditions. We include modeling and computational experience inspired by requirements for air surveillance by the Turkish government’s public agencies. We model these demands in multiple mission areas and consider the impact of different weather conditions on the ability to employ UAVs from different geographic locations. We formulate the problem as a two-stage stochastic integer linear program with recourse and get an optimal solution for realistic test instances in a reasonable amount of time using decomposition by weather and mission combinations. We also introduce an optimization-based heuristic with bounds based on our decomposition for larger test instances.
Hubs are special facilities that serve as switching, transshipment and sorting points in many-to-... more Hubs are special facilities that serve as switching, transshipment and sorting points in many-to-many distribution systems. In hub location problems, transfers between origin-destination points do not take place directly between each other, but by means of hubs for the purpose of taking advantages of economies of scale. Thus, it becomes possible to provide connections to more points with less lines and costs. In this study, a real hub location problem is studied for a public institution. On the basis of the institutions’ demands and the problems’ requirements, a new dimension has been provided to the capacitated multiple allocation hub location problems which have significance in the literature. Unlike the studies conducted in the literature, obligation to use hubs among the origin-destination pairs that are unselected hub is relaxed and the capacities of nodes that are selected as hubs are provided to be affected by the flows both from the hubs and the spokes.
Bu çalışmada bir kamu kurumuna personel yetiştirmekle sorumlu olan ve dört yıllık eğitim hizmeti ... more Bu çalışmada bir kamu kurumuna personel yetiştirmekle sorumlu olan ve dört yıllık eğitim hizmeti sağlayan bir okuldaki eğitim durumu incelenmiştir. Kamu kurumunun ihtiyaç duyduğu insan gücünün tamamı bu okuldan mezun olmaktadır. Bu çalışmanın başta okula alınacak öğrenci miktarlarının belirlenmesi olmak üzere çeşitli insan gücü planlama faaliyetlerinde sıhhatli veriler sağlayacağı değerlendirilmektedir. Çalışmada kamu kurumunun yetişmiş personel sıkıntısı yaşamaması için geleceğe yönelik olarak projeksiyonlar ortaya koyulmuştur. Çalışmada yöntem olarak yöneylem araştırması tekniklerinden Markov Analizi kullanılmıştır. Çalışmanın katkısı kamu kurumu için hayati öneme sahip gerçek bir probleme Markoz Analizi gibi bilimsel bir teknik yardımıyla çözüm önerilmesidir.
Dams are important engineering structures, therefore dams should be
constructed with the rigors o... more Dams are important engineering structures, therefore dams should be constructed with the rigors of safety in mind. In this paper, the vertical displacement of the crest of Keban Dam in Turkey, is determined using a grey prediction method. The grey prediction method is a method that produces satisfactory results when we do not have enough experience about a system behaviors. The purpose of this study is to examine the effectiveness of the grey prediction method in systems where a limited amount of data is available or known. In this study the Simple Exponential Smoothing (SES) method; a very well-known prediction method is used for comparison. The results from our investigation indicate that the grey prediction method produces better results, more in-keeping with true values.
Emerald is a global publisher linking research and practice to the benefit of society. The compan... more Emerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.
Emerald Article: Grey theory based MCDM procedure for sniper selection problem Erkan Kose, Mehmet... more Emerald Article: Grey theory based MCDM procedure for sniper selection problem Erkan Kose, Mehmet Kabak, Hakan Aplak Article information: To cite this document: Erkan Kose, Mehmet Kabak, Hakan Aplak, (2013),"Grey theory based MCDM procedure for sniper selection problem", Grey Systems: Theory and Application, Vol. 3 Iss: 1 pp. 35 -45 Permanent link to this document: http://dx.
Purpose -The relationship between energy consumption (EC) and economic growth is a well-known and... more Purpose -The relationship between energy consumption (EC) and economic growth is a well-known and more studied subject in literature. In this study, Turkey's EC and gross domestic product (GDP) relation is analyzed. The aim of this study is to find out the relative importance of energy components on GDP for Turkey. Hence, the authors can make some strategic implications up to the importance of energy components on GDP. Design/methodology/approach -In this study, two methods are used to find out the importance of energy types on economic growth for Turkey. First, grey relational analysis (GRA) is used to determine the most influential energy types on GDP. Then regression analysis is used to compare outcomes which are yielded by GRA. Findings -The analyses of the results show that the most important energy sources are oil and renewables for Turkey. Both energy sources have equal importance with economic growth. However, it is implied that this balance should be destabilized for the sake of renewable production and usage to have less carbon footprint. Originality/value -There are many econometric models used for defining EC and economic growth causality. But the authors could not come across any study which investigates relationship between economic growth and EC by GRA. The method that is newly used for this subject and applying analysis for a developing country is the importance of this study.
Purpose -Green supply chain management (GSCM) has become an important issue with increasing aware... more Purpose -Green supply chain management (GSCM) has become an important issue with increasing awareness of environmental protection. A firm's environmental approach is not only relevant to its inner efforts, but its suppliers' environmental performance is also important. The aim of this study is to propose an integrated multi-criteria decision-making (MCDM) approach based on intuitionistic fuzzy set (IFS) and grey relational analysis (GRA) for green supplier selection. Design/methodology/approach -Green supplier selection is a MCDM process that contains different kinds of uncertainties. Because of the vagueness and imprecision of decision makers' evaluations and subjectivity of the criteria, IFS and GRA are exploited to handle these uncertainties. Findings -A numerical example is presented for the proposed approach. The analyses of the results show that fuzzy set theory and grey theory can be used jointly for green supplier selection problems in uncertain environments. Originality/value -There are different kinds of uncertainties in the supplier selection process. The novelty of this study is to use proper uncertainty methods in different steps instead of denoting the whole selection process by the same uncertainty theory. Supplier selection problems occupy wide space in operations research literature. Different criteria are used in different papers. In this study, detailed literature review has been carried out and some criteria among frequently confronted ones proposed for green supplier selection.
Due to an increasing demand for energy and rising energy prices, efficiency in energy consumption... more Due to an increasing demand for energy and rising energy prices, efficiency in energy consumption is fast-becoming a topic of significance. The building and construction sector has seen an increase of approximately 30-40% of overall energy consumption occurred; this has exceeded other major sectors such as industry and transport. Given the number of buildings and the cost of energy required to support these buildings, the developing of new approaches in the construction sector will be likely. This situation forces the various stakeholders to implement energy rating procedures to assess buildings' energy performance. The most commonly utilized building environment assessment method currently used in Europe is the Building Research Establishment Environmental Assessment Method (BREEAM). Parallel to Europe, Turkey started its National Building Energy Performance Calculation Methodology (BEP-TR) in 2010. BREEAM and BEP-TR like other methods, require a lot of detailed and particular information in order to be implemented, and the procedure is fairly complicated. In addition, decision support systems can involve assessments, developed as a result of imprecise data in a qualitative manner. "Fuzzy set theory" can play a significant role in this kind of decision-making situation. This paper examines a "fuzzy multi-criteria decision making (MCDM)" approach in order to analyze BEP-TR. This approach was applied to categorize alternative buildings according to their overall energy performance. Results are discussed in terms of developing a new and practical building rating system.
Turk Silahli Kuvvetleri (TSK) personeli uzun yillar calisma hayati sonrasinda emeklilige hazirlan... more Turk Silahli Kuvvetleri (TSK) personeli uzun yillar calisma hayati sonrasinda emeklilige hazirlanirken daha once karsilasmadigi “Nerede yasayacagim? Yasayacagim sehri secerken nelere dikkat etmeliyim?” sorulari ile karsilasmaktadir. Bu calismanin amaci, benzer sorulara cevap arayan TSK personeline, objektif yasam kosullari ve personel tercihlerinin bileskesinden elde edilen bir bolge/sehir secim sistemi gelistirmektir. Bu calismanin TSK emeklisi personelin hayatinin geri kalan bolumunu buyuk olcude etkileyecek olan karmasik bir problemin cozumunde yardimci olacagi degerlendirilmektedir. Ayrica TSK emeklisi personeline yonelik olarak cesitli yatirimlar yapmayi planlayan kuruluslar icin de bu yatirimlari nerelerde yogunlastirmalari gerektigi hususunda onemli bilgiler sunacagi dusunulmektedir.
The success of businesses today is largely dependent on their ability to find solutions to comple... more The success of businesses today is largely dependent on their ability to find solutions to complex problems they encounter. Vehicle selection, which requires considering many objective and subjective criteria, is at the top of these problems. The tramway selection problem of a company operating in the public transport sector in Turkey is discussed in this study. The company wants to increase passenger carrying capacity and renew its vehicle fleet. For this purpose, it has to choose from eight alternative vehicles with different superior features. Considering the high costs that may arise from wrong selection, it becomes clear how important it is to use the right method to solve the problem. In this study, the evaluation criteria were determined by taking the opinions of experts first. Then, weights were assigned to the criteria using the Analytical Hierarchy Process (AHP). In the last stage, the best alternative has been tried to be determined by using grey relationship analysis (GRA). It is common to use more than one method to test the reliability of the results in solving multi-criteria decision-making (MCDM) problems. In this study, multi-objective optimization, based on ratio analysis (MOORA), which is one of the most preferred methods to solve MCDM problems, was used to test the accuracy of the results. Although various MCDM methods are used in the literature to solve similar problems, the use of grey relationship analysis has not been encountered. With this aspect, this study has expanded the application of grey theory and made an important contribution to the literature. Another important contribution of the study is that the evaluation criteria for the tramway selection problem have been determined with the help of experts. Finally, this study presents a scientific approach to the solution of a complex real-life problem.
Supply chain contracts are important tools for sharing risk and increasing overall supply chain p... more Supply chain contracts are important tools for sharing risk and increasing overall supply chain profitability. Research on supply chain contracts shows that supply chain actors can make more profit if they cooperate with other actors instead of acting alone. Game theory has become an important tool in the analysis of supply chains with multiple actors whose primary purpose is to increase their own profits. In cooperative games, players try to get more than they can alone by forming coalitions. In this study, buyback contract, which is one of the most used contract types in order to ensure supply chain coordination, is tried to be handled with the game theory. Considering the similarity of the relations between game theory and supply chain actors, it is aimed to distribute the profits of the supply chain more equitably. In the study the gains that the supply chain actors will gain in case of using buyback contract for different coalition options are calculated. Then, a game theory-based approach was followed to distribute profits fairly among supply chain actors. The results showed that the proposed approach can provide a more equitable profit sharing among supply chain actors. The main contribution of this study to the literature is that the profit sharing between supply chain actors has not been handled with the logic of game theory until this time. Therefore, it is thought that this study will open the door to examining other supply chain contracts within the scope of cooperative games.
Günümüz rekabet şartlarında işletmeleri hedeflerine ulaştıracak olan; kurumsallaşma faaliyetlerin... more Günümüz rekabet şartlarında işletmeleri hedeflerine ulaştıracak olan; kurumsallaşma faaliyetlerinin geliştirilmesi, yurtiçi ve yurt dışı pazarların artırılması, tanınırlık faaliyetlerinin sistematik olarak yürütülmesi, iş süreçlerinin etkin ve verimli yönetilmesine yönelik gerekli iyileştirme ve geliştirme süreçlerinin işlerliği gibi tüm çalışma alanlarının asıl ve dinamik yapısını oluşturan ana etken, insan faktörüdür. Bu nedenle, işletmelerde personel seçimi oldukça önemlidir. Personel seçim sürecinin başarılı şekilde tamamlanması, işletmenin verimliliğini olumlu yönde etkilerken; yanlış seçimler üretim aşamasını, kaynakların kullanılabilirliğini olumsuz yönde etkileyerek müşteri ve pazar kayıplarına sebep olmaktadır. Personel seçimine önem verilmediğinde, hem işletme zarara uğramakta hem de personelin motivasyonu olumsuz etkilenmektedir. Personel seçiminde nitel değerlendirmelerin yanı sıra nicel değerlendirmelerin de yapılması, işletmeler açısından hayati öneme sahip olan bu sürecin başarı şansını artırmakta ve daha doğru seçim yapılmasına katkı sağlamaktadır. Bu çalışma kapsamında, Kayseri ili Organize Sanayi Bölgesi içerisinde yer alan orta ölçekli bir işletmenin personel seçim problemi ele alınmıştır. İş başvurusunda bulunan adaylar belirlenen kriterlere sahip olma düzeylerine göre sıralamaya tabi tutulmuşlardır. Değerlendirmede kullanılan kriterler eşit öneme sahip olmadığından kriter ağırlıklarının belirlenmesi aşamasında Analitik Hiyerarşi Yöntemi (AHP), adayların sıralamasında ise VIKOR Yöntemi kullanılmıştır. Elde edilen sonuçlar personel seçiminde AHP ve VIKOR yöntemlerinin bütünleşik olarak etkili bir şekilde kullanılabileceğini göstermiştir.
Most of today's optimization efforts aim to reduce costs, time or the number of resources used. H... more Most of today's optimization efforts aim to reduce costs, time or the number of resources used. However, optimization efforts should consider other factors as important as these, such as facilitating the lives of the disabled, elderly and pregnant and helping them in their daily lives. In this study, the Nuh Naci Yazgan (NNY) University (Kayseri/Turkey) personnel transport problems were discussed. The NNY University provides a shuttle service to bring employees to school at the start of the work and to leave them at home after work. In order to shorten the collection / distribution time and the total distance travelled, the service vehicle does not leave / pick up all employees in front of their homes. Instead, the employees are picked up / dropped at appropriate locations on an intuitively determined route. Since only the time and cost savings are taken into account when determining the service route, some employees have a long walking distance to the service route. This creates a very important problem, especially for the disabled and pregnant workers. In this study, a new mathematical model is proposed which takes into consideration the physical disadvantages and occupational positions of the employees in order to determine the shortest vehicle route. The results show that the proposed model can significantly reduce walking distances of physically disabled people without compromising the total distance travelled by the vehicle.
Journal of Applied Research on Industrial Engineering, 2020
Bed production has an important market in the furniture sector. In spite of the fact that sponge ... more Bed production has an important market in the furniture sector. In spite of the fact that sponge is generally preferred as filler in the production process of beds, increasing prices in recent years and the preference of new materials with the development of alternative filling materials have increased. Recently it is seen other than sponge, the granule, wadding, and STW are also used as filling material in bed production. From the management point of view, the choice of filler is an important decision problem that depends on the situation of the business and many objective and subjective criteria must be taken into consideration. It is appropriate to examine such a problem with the Analytical Hierarchy Method (AHP) and the ELECTRE method, which have the ability to make quantitative evaluations and synthesize factor weights from subjective judgments. The criteria for selection of the filler material and the extent to which the criterion will affect the evaluation are important decision points. The opinions of experts in bed production were consulted to determine the criteria to be used in the evaluation. The obtained results show that four basic criteria must be taken into consideration in the selection of filler material. In this study, AHP was used for determining the criteria weights, and ELECTRE methods were used for the selection of the best filling material. The results showed that wadding is the optimum filler material for bed production.
Purpose -The purpose of this paper is to examine the effectiveness of the multivariable grey pred... more Purpose -The purpose of this paper is to examine the effectiveness of the multivariable grey prediction model in deformation forecasting. Design/methodology/approach -Deformation in a dam can be seen because of many factors but without any doubt, the most influential factor is the water level. In this study, the deformation level of a point in the Keban Dam crest has been tried to be forecasted depending on the water level by the multivariable grey model GM(1,N). Regression analysis was used to test the accuracy of the prediction results obtained using the grey prediction model. Findings -The results show that there is a great consistency between the grey prediction values and the actual values, and that the GM(1,N) produces more reliable results than the regression analysis. Based on the results, it can be concluded that the GM(1,N) is a very reliable estimation model for limited data conditions. Originality/value -Different from the other studies in the literature, this study investigates deformation in a dam subject to the water level in the dam reservoir. The main contribution of the study to the literature is to suggest a relatively new procedure for estimating the deformation in the dams based on the water level.
Grey theory is one of the methods used to study uncertainty. The uncertain systems characterized ... more Grey theory is one of the methods used to study uncertainty. The uncertain systems characterized by small sample and poor information are the study object of grey system theory. Multivariable grey prediction models are part of grey forecasting system. They are presented if there are mutual relations among the factors in the system. They believe that all the influencing factors are not independent of each other and should be regarded as a whole. In multivariable grey forecasting models, the future value of a variable is tried to be forecasted considering the other influential factors in the system. In this study, deformation consisting on the crest of a Dam is aimed to determine by using multivariable grey prediction models. Özet Gri teori, belirsizliği incelemek için kullanılan yöntemlerden biridir. Sınırlı bilgi ve küçük örnekler ile karakterize edilmiş belirsiz sistemler, gri sistem teorisinin inceleme konusudur. Çok değişkenli gri tahmin modelleri gri tahmin sisteminin parçasıdır. Sistemdeki faktörler arasında karşılıklı ilişkiler varsa onlar temsil edilirler. Etkileyen faktörler birbirinden bağımsız değildir ve bir bütün olarak kabul edilmektedir. Çok değişkenli gri tahmin modeli, bir değişkenin gelecek değerini sistemdeki diğer etkilenen faktörleri göz önüne alarak tahmin etmeye çalışmaktadır. Bu çalışmada, çok değişkenli gri tahmin modeli kullanarak bir barajın kreti üzerinde oluşan deformasyonların tahmin edilmesi amaçlanmıştır.
Purpose-The purpose of this paper is to examine the effectiveness of the multivariable grey predi... more Purpose-The purpose of this paper is to examine the effectiveness of the multivariable grey prediction model in deformation forecasting. Design/methodology/approach-Deformation in a dam can be seen because of many factors but without any doubt, the most influential factor is the water level. In this study, the deformation level of a point in the Keban Dam crest has been tried to be forecasted depending on the water level by the multivariable grey model GM(1,N). Regression analysis was used to test the accuracy of the prediction results obtained using the grey prediction model. Findings-The results show that there is a great consistency between the grey prediction values and the actual values, and that the GM(1,N) produces more reliable results than the regression analysis. Based on the results, it can be concluded that the GM(1,N) is a very reliable estimation model for limited data conditions. Originality/value-Different from the other studies in the literature, this study investigates deformation in a dam subject to the water level in the dam reservoir. The main contribution of the study to the literature is to suggest a relatively new procedure for estimating the deformation in the dams based on the water level.
Purpose-The purpose of this paper is to present a mixed integer programming model for simple asse... more Purpose-The purpose of this paper is to present a mixed integer programming model for simple assembly line balancing problems (SALBP) with Type 1 when the annual demand and task durations are uncertain and encoded with grey numbers. Design/methodology/approach-Grey theory and grey numbers are used for illustrating the uncertainty of parameters in an SALBP, where the objective is to minimize the total number of workstations. The paper proposes a 0-1 mathematical model for SALBP of Type 1 with grey demand and grey task durations. Findings-The uncertainty of the demand and task durations are encoded with grey numbers and a well-known 0-1 mathematical model for SALBP of Type 1 is modified to find the minimum number of workstations in order to meet both the lower and upper bounds of the uncertain demand. The results obtained from the proposed mathematical model show a task-workstation assignment that does not distribute precedence relations among tasks and workstations and the sum of task durations in each single workstation is less than or equal to the grey cycle time. Originality/value-The grey theory and grey numbers have not been previously used to identify uncertainties in assembly line balancing problems. Therefore, this study provides an important contribution to the literature.
Project scheduling has been still one of the hottest topics in the management area. The goal of t... more Project scheduling has been still one of the hottest topics in the management area. The goal of traditional project management is to complete the project at the earliest possible time in accordance with the available resources without violating priority relations of the activities involved. Unlike traditional project management, this study deals with the possibility of a coalition among the staff available to accomplish tasks of the project. The tasks can be fulfilled by more than one staff members. Staff’s coalition shortens the completion time of the tasks. A natural problem that arises in this case is how to share the income generated. The other side of the problem is concerned with the project owner who wants the project to be completed as early as possible. In this study, a mathematical model proposal is dealt with in order to real-ize the goals of both the project owner and the staffs as much as possible within the complex structure of the situation.
Motivated by the increasing civilian use of Unmanned Aerial Vehicles (UAVs), this paper considers... more Motivated by the increasing civilian use of Unmanned Aerial Vehicles (UAVs), this paper considers the simultaneous location and routing of UAVs for multiple missions and different weather conditions. We include modeling and computational experience inspired by requirements for air surveillance by the Turkish government’s public agencies. We model these demands in multiple mission areas and consider the impact of different weather conditions on the ability to employ UAVs from different geographic locations. We formulate the problem as a two-stage stochastic integer linear program with recourse and get an optimal solution for realistic test instances in a reasonable amount of time using decomposition by weather and mission combinations. We also introduce an optimization-based heuristic with bounds based on our decomposition for larger test instances.
Hubs are special facilities that serve as switching, transshipment and sorting points in many-to-... more Hubs are special facilities that serve as switching, transshipment and sorting points in many-to-many distribution systems. In hub location problems, transfers between origin-destination points do not take place directly between each other, but by means of hubs for the purpose of taking advantages of economies of scale. Thus, it becomes possible to provide connections to more points with less lines and costs. In this study, a real hub location problem is studied for a public institution. On the basis of the institutions’ demands and the problems’ requirements, a new dimension has been provided to the capacitated multiple allocation hub location problems which have significance in the literature. Unlike the studies conducted in the literature, obligation to use hubs among the origin-destination pairs that are unselected hub is relaxed and the capacities of nodes that are selected as hubs are provided to be affected by the flows both from the hubs and the spokes.
Bu çalışmada bir kamu kurumuna personel yetiştirmekle sorumlu olan ve dört yıllık eğitim hizmeti ... more Bu çalışmada bir kamu kurumuna personel yetiştirmekle sorumlu olan ve dört yıllık eğitim hizmeti sağlayan bir okuldaki eğitim durumu incelenmiştir. Kamu kurumunun ihtiyaç duyduğu insan gücünün tamamı bu okuldan mezun olmaktadır. Bu çalışmanın başta okula alınacak öğrenci miktarlarının belirlenmesi olmak üzere çeşitli insan gücü planlama faaliyetlerinde sıhhatli veriler sağlayacağı değerlendirilmektedir. Çalışmada kamu kurumunun yetişmiş personel sıkıntısı yaşamaması için geleceğe yönelik olarak projeksiyonlar ortaya koyulmuştur. Çalışmada yöntem olarak yöneylem araştırması tekniklerinden Markov Analizi kullanılmıştır. Çalışmanın katkısı kamu kurumu için hayati öneme sahip gerçek bir probleme Markoz Analizi gibi bilimsel bir teknik yardımıyla çözüm önerilmesidir.
Dams are important engineering structures, therefore dams should be
constructed with the rigors o... more Dams are important engineering structures, therefore dams should be constructed with the rigors of safety in mind. In this paper, the vertical displacement of the crest of Keban Dam in Turkey, is determined using a grey prediction method. The grey prediction method is a method that produces satisfactory results when we do not have enough experience about a system behaviors. The purpose of this study is to examine the effectiveness of the grey prediction method in systems where a limited amount of data is available or known. In this study the Simple Exponential Smoothing (SES) method; a very well-known prediction method is used for comparison. The results from our investigation indicate that the grey prediction method produces better results, more in-keeping with true values.
Emerald is a global publisher linking research and practice to the benefit of society. The compan... more Emerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.
Emerald Article: Grey theory based MCDM procedure for sniper selection problem Erkan Kose, Mehmet... more Emerald Article: Grey theory based MCDM procedure for sniper selection problem Erkan Kose, Mehmet Kabak, Hakan Aplak Article information: To cite this document: Erkan Kose, Mehmet Kabak, Hakan Aplak, (2013),"Grey theory based MCDM procedure for sniper selection problem", Grey Systems: Theory and Application, Vol. 3 Iss: 1 pp. 35 -45 Permanent link to this document: http://dx.
Purpose -The relationship between energy consumption (EC) and economic growth is a well-known and... more Purpose -The relationship between energy consumption (EC) and economic growth is a well-known and more studied subject in literature. In this study, Turkey's EC and gross domestic product (GDP) relation is analyzed. The aim of this study is to find out the relative importance of energy components on GDP for Turkey. Hence, the authors can make some strategic implications up to the importance of energy components on GDP. Design/methodology/approach -In this study, two methods are used to find out the importance of energy types on economic growth for Turkey. First, grey relational analysis (GRA) is used to determine the most influential energy types on GDP. Then regression analysis is used to compare outcomes which are yielded by GRA. Findings -The analyses of the results show that the most important energy sources are oil and renewables for Turkey. Both energy sources have equal importance with economic growth. However, it is implied that this balance should be destabilized for the sake of renewable production and usage to have less carbon footprint. Originality/value -There are many econometric models used for defining EC and economic growth causality. But the authors could not come across any study which investigates relationship between economic growth and EC by GRA. The method that is newly used for this subject and applying analysis for a developing country is the importance of this study.
Purpose -Green supply chain management (GSCM) has become an important issue with increasing aware... more Purpose -Green supply chain management (GSCM) has become an important issue with increasing awareness of environmental protection. A firm's environmental approach is not only relevant to its inner efforts, but its suppliers' environmental performance is also important. The aim of this study is to propose an integrated multi-criteria decision-making (MCDM) approach based on intuitionistic fuzzy set (IFS) and grey relational analysis (GRA) for green supplier selection. Design/methodology/approach -Green supplier selection is a MCDM process that contains different kinds of uncertainties. Because of the vagueness and imprecision of decision makers' evaluations and subjectivity of the criteria, IFS and GRA are exploited to handle these uncertainties. Findings -A numerical example is presented for the proposed approach. The analyses of the results show that fuzzy set theory and grey theory can be used jointly for green supplier selection problems in uncertain environments. Originality/value -There are different kinds of uncertainties in the supplier selection process. The novelty of this study is to use proper uncertainty methods in different steps instead of denoting the whole selection process by the same uncertainty theory. Supplier selection problems occupy wide space in operations research literature. Different criteria are used in different papers. In this study, detailed literature review has been carried out and some criteria among frequently confronted ones proposed for green supplier selection.
Due to an increasing demand for energy and rising energy prices, efficiency in energy consumption... more Due to an increasing demand for energy and rising energy prices, efficiency in energy consumption is fast-becoming a topic of significance. The building and construction sector has seen an increase of approximately 30-40% of overall energy consumption occurred; this has exceeded other major sectors such as industry and transport. Given the number of buildings and the cost of energy required to support these buildings, the developing of new approaches in the construction sector will be likely. This situation forces the various stakeholders to implement energy rating procedures to assess buildings' energy performance. The most commonly utilized building environment assessment method currently used in Europe is the Building Research Establishment Environmental Assessment Method (BREEAM). Parallel to Europe, Turkey started its National Building Energy Performance Calculation Methodology (BEP-TR) in 2010. BREEAM and BEP-TR like other methods, require a lot of detailed and particular information in order to be implemented, and the procedure is fairly complicated. In addition, decision support systems can involve assessments, developed as a result of imprecise data in a qualitative manner. "Fuzzy set theory" can play a significant role in this kind of decision-making situation. This paper examines a "fuzzy multi-criteria decision making (MCDM)" approach in order to analyze BEP-TR. This approach was applied to categorize alternative buildings according to their overall energy performance. Results are discussed in terms of developing a new and practical building rating system.
Turk Silahli Kuvvetleri (TSK) personeli uzun yillar calisma hayati sonrasinda emeklilige hazirlan... more Turk Silahli Kuvvetleri (TSK) personeli uzun yillar calisma hayati sonrasinda emeklilige hazirlanirken daha once karsilasmadigi “Nerede yasayacagim? Yasayacagim sehri secerken nelere dikkat etmeliyim?” sorulari ile karsilasmaktadir. Bu calismanin amaci, benzer sorulara cevap arayan TSK personeline, objektif yasam kosullari ve personel tercihlerinin bileskesinden elde edilen bir bolge/sehir secim sistemi gelistirmektir. Bu calismanin TSK emeklisi personelin hayatinin geri kalan bolumunu buyuk olcude etkileyecek olan karmasik bir problemin cozumunde yardimci olacagi degerlendirilmektedir. Ayrica TSK emeklisi personeline yonelik olarak cesitli yatirimlar yapmayi planlayan kuruluslar icin de bu yatirimlari nerelerde yogunlastirmalari gerektigi hususunda onemli bilgiler sunacagi dusunulmektedir.
The success of businesses today is largely dependent on their ability to find solutions to comple... more The success of businesses today is largely dependent on their ability to find solutions to complex problems they encounter. Vehicle selection, which requires considering many objective and subjective criteria, is at the top of these problems. The tramway selection problem of a company operating in the public transport sector in Turkey is discussed in this study. The company wants to increase passenger carrying capacity and renew its vehicle fleet. For this purpose, it has to choose from eight alternative vehicles with different superior features. Considering the high costs that may arise from wrong selection, it becomes clear how important it is to use the right method to solve the problem. In this study, the evaluation criteria were determined by taking the opinions of experts first. Then, weights were assigned to the criteria using the Analytical Hierarchy Process (AHP). In the last stage, the best alternative has been tried to be determined by using grey relationship analysis (GRA). It is common to use more than one method to test the reliability of the results in solving multi-criteria decision-making (MCDM) problems. In this study, multi-objective optimization, based on ratio analysis (MOORA), which is one of the most preferred methods to solve MCDM problems, was used to test the accuracy of the results. Although various MCDM methods are used in the literature to solve similar problems, the use of grey relationship analysis has not been encountered. With this aspect, this study has expanded the application of grey theory and made an important contribution to the literature. Another important contribution of the study is that the evaluation criteria for the tramway selection problem have been determined with the help of experts. Finally, this study presents a scientific approach to the solution of a complex real-life problem.
Supply chain contracts are important tools for sharing risk and increasing overall supply chain p... more Supply chain contracts are important tools for sharing risk and increasing overall supply chain profitability. Research on supply chain contracts shows that supply chain actors can make more profit if they cooperate with other actors instead of acting alone. Game theory has become an important tool in the analysis of supply chains with multiple actors whose primary purpose is to increase their own profits. In cooperative games, players try to get more than they can alone by forming coalitions. In this study, buyback contract, which is one of the most used contract types in order to ensure supply chain coordination, is tried to be handled with the game theory. Considering the similarity of the relations between game theory and supply chain actors, it is aimed to distribute the profits of the supply chain more equitably. In the study the gains that the supply chain actors will gain in case of using buyback contract for different coalition options are calculated. Then, a game theory-based approach was followed to distribute profits fairly among supply chain actors. The results showed that the proposed approach can provide a more equitable profit sharing among supply chain actors. The main contribution of this study to the literature is that the profit sharing between supply chain actors has not been handled with the logic of game theory until this time. Therefore, it is thought that this study will open the door to examining other supply chain contracts within the scope of cooperative games.
Günümüz rekabet şartlarında işletmeleri hedeflerine ulaştıracak olan; kurumsallaşma faaliyetlerin... more Günümüz rekabet şartlarında işletmeleri hedeflerine ulaştıracak olan; kurumsallaşma faaliyetlerinin geliştirilmesi, yurtiçi ve yurt dışı pazarların artırılması, tanınırlık faaliyetlerinin sistematik olarak yürütülmesi, iş süreçlerinin etkin ve verimli yönetilmesine yönelik gerekli iyileştirme ve geliştirme süreçlerinin işlerliği gibi tüm çalışma alanlarının asıl ve dinamik yapısını oluşturan ana etken, insan faktörüdür. Bu nedenle, işletmelerde personel seçimi oldukça önemlidir. Personel seçim sürecinin başarılı şekilde tamamlanması, işletmenin verimliliğini olumlu yönde etkilerken; yanlış seçimler üretim aşamasını, kaynakların kullanılabilirliğini olumsuz yönde etkileyerek müşteri ve pazar kayıplarına sebep olmaktadır. Personel seçimine önem verilmediğinde, hem işletme zarara uğramakta hem de personelin motivasyonu olumsuz etkilenmektedir. Personel seçiminde nitel değerlendirmelerin yanı sıra nicel değerlendirmelerin de yapılması, işletmeler açısından hayati öneme sahip olan bu sürecin başarı şansını artırmakta ve daha doğru seçim yapılmasına katkı sağlamaktadır. Bu çalışma kapsamında, Kayseri ili Organize Sanayi Bölgesi içerisinde yer alan orta ölçekli bir işletmenin personel seçim problemi ele alınmıştır. İş başvurusunda bulunan adaylar belirlenen kriterlere sahip olma düzeylerine göre sıralamaya tabi tutulmuşlardır. Değerlendirmede kullanılan kriterler eşit öneme sahip olmadığından kriter ağırlıklarının belirlenmesi aşamasında Analitik Hiyerarşi Yöntemi (AHP), adayların sıralamasında ise VIKOR Yöntemi kullanılmıştır. Elde edilen sonuçlar personel seçiminde AHP ve VIKOR yöntemlerinin bütünleşik olarak etkili bir şekilde kullanılabileceğini göstermiştir.
Kamu yönetimi tüm dünyada yenilikçilik bakış açısı ile yeniden şekillendirilmektedir. Bu değişim ... more Kamu yönetimi tüm dünyada yenilikçilik bakış açısı ile yeniden şekillendirilmektedir. Bu değişim süreci içerisinde yenilikçi kamu satın alması da yenilikçi stratejinin bir aracı olarak kullanılmaya başlanmıştır. Bu çalışmanın amacı, gelişmiş ülkelerde kamu satın almasında yenilikçiliğin nasıl kullanıldığının ortaya konması ve yenilikçi kamu satın almasını uygulayan ülkelerin geliştirdikleri politikaları vurgulamak suretiyle Türkiye'de yenilikçi kamu satın almasının uygulanabilirliğinin tartışılmasıdır. Yapılan çalışma sonucunda Türkiye'nin AB'nin yenilikçi satın alma stratejisine uymak adına yasal bazı düzenlemeler yaptığı, ancak AB uyum sürecinde bunların yeterli olmadığı değerlendirilmiştir. Sonuçta Türkiye'de yenilikçi kamu satın alma stratejisinin uygulanabilmesi için önerilerde bulunulmuştur.
Gunumuz rekabet sartlarinda isletmeleri hedeflerine ulastiracak olan; kurumsallasma faaliyetlerin... more Gunumuz rekabet sartlarinda isletmeleri hedeflerine ulastiracak olan; kurumsallasma faaliyetlerinin gelistirilmesi, yurtici ve yurt disi pazarlarin artirilmasi, taninirlik faaliyetlerinin sistematik olarak yurutulmesi, is sureclerinin etkin ve verimli yonetilmesine yonelik gerekli iyilestirme ve gelistirme sureclerinin islerligi gibi tum calisma alanlarinin asil ve dinamik yapisini olusturan ana etken, insan faktorudur. Bu nedenle, isletmelerde personel secimi oldukca onemlidir. Personel secim surecinin basarili sekilde tamamlanmasi, isletmenin verimliligini olumlu yonde etkilerken; yanlis secimler uretim asamasini, kaynaklarin kullanilabilirligini olumsuz yonde etkileyerek musteri ve pazar kayiplarina sebep olacaktir. Personel secimine onem verilmediginde, hem isletme zarara ugrayacak hem de personelin motivasyonu olumsuz etkilenecektir. Personel seciminde nitel degerlendirmelerin yani sira nicel degerlendirmelerin de yapilmasi, isletmeler acisindan hayati oneme sahip olan bu surec...
Bu calismada bir kamu kurumuna personel yetistirmekle sorumlu olan ve dort yillik egitim hizmeti ... more Bu calismada bir kamu kurumuna personel yetistirmekle sorumlu olan ve dort yillik egitim hizmeti saglayan bir okuldaki egitim durumu incelenmistir. Kamu kurumunun ihtiyac duydugu insan gucunun tamami bu okuldan mezun olmaktadir. Bu calismanin basta okula alinacak ogrenci miktarlarinin belirlenmesi olmak uzere cesitli insan gucu planlama faaliyetlerinde sihhatli veriler saglayacagi degerlendirilmektedir. Calismada kamu kurumunun yetismis personel sikintisi yasamamasi icin gelecege yonelik olarak projeksiyonlar ortaya koyulmustur. Calismada yontem olarak yoneylem arastirmasi tekniklerinden Markov Analizi kullanilmistir. Calismanin katkisi kamu kurumu icin hayati oneme sahip gercek bir probleme Markoz Analizi gibi bilimsel bir teknik yardimiyla cozum onerilmesidir.
Private Pension System (PPS) has an important place in developed societies. Legal regulations whi... more Private Pension System (PPS) has an important place in developed societies. Legal regulations which have been carried out recently made PPS desirable for investors also in our country. Correspondingly the number of PPS companies which operate in our country has increased visibly. For investors selecting the best alternative among plenty of PPS companies is an important decision problem
The existing literature documents that computer simulations can reveal how characteristics of mic... more The existing literature documents that computer simulations can reveal how characteristics of micro-level individuals give rise to macro-level phenomena of systemic wholes. This paper seeks to establish such an important simulation-based observation as a theoretical result on a sound foundation. Going beyond addressing when holistic phenomena can naturally emerge from micro-level characteristics, this paper investigates how and why many macro-level entities appear to answer market calls through organically gathering micro-level agents into uniformly-oriented operational wholes, even though these agents have inconsistent or even conflicting interests. This paper develops conclusions based on results of systems science and establishes a sufficient condition under which characteristics of micro-level agents can naturally lead to the appearance of macro-level properties of a systemic whole even though the former are heterogeneous and behave in an unintended and uncoordinated manner. Thi...
Gri tahmin yöntemi sistem davranışları hakkında yeterli tecrübemizin bulunmadığı ve sınırlı sayıd... more Gri tahmin yöntemi sistem davranışları hakkında yeterli tecrübemizin bulunmadığı ve sınırlı sayıda veriye ulaşılabildiği durumlarda tatmin edici sonuçlar üretebilen bir tahmin yöntemidir. Bu çalışmanın amacı, doğası gereği sınırlı sayıda veriye ulaşılabilen sistemler için gri tahmin yönteminin etkinliğini test etmektir. Çalışmada bir üniversitede dört yıllık lisans eğitimini tamamlamış öğrencilerin ilk beş yarıyıllık akademik başarı ortalamaları kullanılarak mezuniyet notları tahmin edilmeye çalışılmış ve elde edilen sonuçlar gerçek mezuniyet notları ile karşılaştırılmıştır. Ulaşılan sonuçlar incelendiğinde gri tahmin yönteminin yetersiz veri ortamında oldukça iyi sayılabilecek tahmin sonuçları ürettiği görülmüştür.
In this paper we consider and present formulations and solution approaches for the capacitated mu... more In this paper we consider and present formulations and solution approaches for the capacitated multiple allocation hub location problem. We present a new mixed integer linear programming formulation for the problem. We also construct an ecient heuristic algorithm, using shortest paths. We incorporate the upper bound obtained from this heuristic in a linear-programming-based branch-and-bound solution procedure. We present the results of extensive computational experience with both the heuristic and the exact methods.
Bed production has an important market in the furniture sector. In spite of the fact that sponge ... more Bed production has an important market in the furniture sector. In spite of the fact that sponge is generally preferred as filler in the production process of beds, increasing prices in recent years and the preference of new materials with the development of alternative filling materials have increased. Recently it is seen other than sponge, granule, wadding and STW are also used as filling material in bed production. From the management point of view, the choice of filler is an important decision problem that depends on the situation of the business and many objective and subjective criteria must be taken into consideration. It is appropriate to examine such a problem with the Analytical Hierarchy Method (AHP) and the ELECTRE method, which have the ability to make quantitative evaluations and synthesize factor weights from subjective judgments.The criteria for selection of the filler material and the extent to which the criterion will affect the evaluation are important decision po...
Most of today's optimization efforts aim to reduce costs, time or the number of resources use... more Most of today's optimization efforts aim to reduce costs, time or the number of resources used. However, optimization efforts should consider other factors as important as these, such as facilitating the lives of the disabled, elderly and pregnant and helping them in their daily lives. In this study, the Nuh Naci Yazgan (NNY) University (Kayseri/Turkey) personnel transport problems were discussed. The NNY University provides a shuttle service to bring employees to school at the start of the work and to leave them at home after work. In order to shorten the collection / distribution time and the total distance travelled, the service vehicle does not leave / pick up all employees in front of their homes. Instead, the employees are picked up / dropped at appropriate locations on an intuitively determined route. Since only the time and cost savings are taken into account when determining the service route, some employees have a long walking distance to the service route. This create...
Purpose The purpose of this paper is to examine the effectiveness of the multivariable grey predi... more Purpose The purpose of this paper is to examine the effectiveness of the multivariable grey prediction model in deformation forecasting. Design/methodology/approach Deformation in a dam can be seen because of many factors but without any doubt, the most influential factor is the water level. In this study, the deformation level of a point in the Keban Dam crest has been tried to be forecasted depending on the water level by the multivariable grey model GM(1,N). Regression analysis was used to test the accuracy of the prediction results obtained using the grey prediction model. Findings The results show that there is a great consistency between the grey prediction values and the actual values, and that the GM(1,N) produces more reliable results than the regression analysis. Based on the results, it can be concluded that the GM(1,N) is a very reliable estimation model for limited data conditions. Originality/value Different from the other studies in the literature, this study investig...
Motivated by the increasing civilian use of Unmanned Aerial Vehicles (UAVs), this paper considers... more Motivated by the increasing civilian use of Unmanned Aerial Vehicles (UAVs), this paper considers the simultaneous location and routing of UAVs for multiple missions and different weather conditions. We include modeling and computational experience inspired by requirements for air surveillance by the Turkish government’s public agencies. We model these demands in multiple mission areas and consider the impact of different weather conditions on the ability to employ UAVs from different geographic locations. We formulate the problem as a two-stage stochastic integer linear program with recourse and get an optimal solution for realistic test instances in a reasonable amount of time using decomposition by weather and mission combinations. We also introduce an optimization-based heuristic with bounds based on our decomposition for larger test instances.
In this study, a military decision problem is handled by an integrated approach based on game the... more In this study, a military decision problem is handled by an integrated approach based on game theory and geographical information systems (GIS). The problem can be defined as: finding layout plan for troops who want to maximize probability of identifying enemies using particular routes to penetrate border line. The problem has been transformed to two-person zero-sum game by some assumptions and solved in four interconnected stages. First, suitable spots in the terrain for monitoring the enemies were identified. Then, visibility percentages of each of the spots were calculated by using GIS for the routes used by enemies to pass the border line. Next, by assuming the calculated visibility ratios as the probability of identifying the enemy, a two-person zero-sum payoff matrix was formed. Finally, linear mathematical model established to obtain optimal strategies with their probabilities. There are many techniques in literature to solve military decision problems but we believe that this study, by holding the peculiarity of the first study in which game theory and GIS are used together, will make a significant contribution to literature and future studies.
Gelecege yonelik senaryolar nasil olusturulur? Gelecegin planlamasi nasil yapilir? Bu sorularin c... more Gelecege yonelik senaryolar nasil olusturulur? Gelecegin planlamasi nasil yapilir? Bu sorularin cevabinin verilebilmesi gelecege yonelik belirsizliklerin ortadan kaldirilmasi ile mumkun olacaktir. Senaryo planlama, gelecege yonelik belirsizlikleri yonetmek ve stratejik planlama surecini verimli hale getirmek amaciyla kullanilan onemli bir yonetim ve sistem surecidir. Calismada, senaryo planlama sureci, ozellikleri ve teknikleri ile ilgili literatur arastirmasi, ornek bir uygulama ile degerlendirme bolumleri yer almaktadir
Dams are important engineering structures, therefore dams should be constructed with the rigors o... more Dams are important engineering structures, therefore dams should be constructed with the rigors of safety in mind. In this paper, the vertical displacement of the crest of Keban Dam in Turkey, is determined using a grey prediction method. The grey prediction method is a method that produces satisfactory results when we do not have enough experience about a system behaviors. The purpose of this study is to examine the effectiveness of the grey prediction method in systems where a limited amount of data is available or known. In this study the Simple Exponential Smoothing (SES) method; a very well-known prediction method is used for comparison. The results from our investigation indicate that the grey prediction method produces better results, more in-keeping with true values.
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Erkan Kose by Erkan köse
systems. In hub location problems, transfers between origin-destination points do not take place directly between
each other, but by means of hubs for the purpose of taking advantages of economies of scale. Thus, it becomes
possible to provide connections to more points with less lines and costs. In this study, a real hub location
problem is studied for a public institution. On the basis of the institutions’ demands and the problems’
requirements, a new dimension has been provided to the capacitated multiple allocation hub location problems
which have significance in the literature. Unlike the studies conducted in the literature, obligation to use hubs
among the origin-destination pairs that are unselected hub is relaxed and the capacities of nodes that are selected
as hubs are provided to be affected by the flows both from the hubs and the spokes.
constructed with the rigors of safety in mind. In this paper, the vertical
displacement of the crest of Keban Dam in Turkey, is determined using a grey
prediction method. The grey prediction method is a method that produces
satisfactory results when we do not have enough experience about a system
behaviors. The purpose of this study is to examine the effectiveness of the grey
prediction method in systems where a limited amount of data is available or known.
In this study the Simple Exponential Smoothing (SES) method; a very well-known
prediction method is used for comparison. The results from our investigation
indicate that the grey prediction method produces better results, more in-keeping
with true values.
Papers by Erkan köse
systems. In hub location problems, transfers between origin-destination points do not take place directly between
each other, but by means of hubs for the purpose of taking advantages of economies of scale. Thus, it becomes
possible to provide connections to more points with less lines and costs. In this study, a real hub location
problem is studied for a public institution. On the basis of the institutions’ demands and the problems’
requirements, a new dimension has been provided to the capacitated multiple allocation hub location problems
which have significance in the literature. Unlike the studies conducted in the literature, obligation to use hubs
among the origin-destination pairs that are unselected hub is relaxed and the capacities of nodes that are selected
as hubs are provided to be affected by the flows both from the hubs and the spokes.
constructed with the rigors of safety in mind. In this paper, the vertical
displacement of the crest of Keban Dam in Turkey, is determined using a grey
prediction method. The grey prediction method is a method that produces
satisfactory results when we do not have enough experience about a system
behaviors. The purpose of this study is to examine the effectiveness of the grey
prediction method in systems where a limited amount of data is available or known.
In this study the Simple Exponential Smoothing (SES) method; a very well-known
prediction method is used for comparison. The results from our investigation
indicate that the grey prediction method produces better results, more in-keeping
with true values.