103 research outputs found
Modeling of carbon credit prices using regime switching approach
No full textSemra Ağralı (MEF Author)In this study, we analyze the price dynamics of carbon certificates that are traded under the European Union's Emissions Trading System (EU-ETS). With the aim of investigating the joint relations among carbon, electricity, and fuel prices, we model historical prices using several methods and incorporating structural changes, such as econometric time series, regime switching, and multivariate vector autoregression models. We compare the results of the structural model with the results of traditional Markov switching and autoregressive models with breaks and present performance analysis based on the mean average percentage error, root mean squared error, and coefficient of determination. According to these performance tests, models with regimes outperform the approaches where breaks are defined using ex ante dummy variables. Moreover, we conclude that among regime switching models, univariate models are better than multivariate counterparts for modeling carbon price series for the analysis of both in-sample and out-of-samples. Published by AIP Publishing.WOS:0004372803000422-s2.0-85049234517Science Citation Index Expanded - Social Sciences Citation IndexArticleUluslararası işbirliği ile yapılmayan - HAYIRMayısYÖK - 2017-1
Nonlinear benefit-cost optimization-based selection of insulation material and window type: A case study in Turkey
No full textSemra Ağralı (MEF Author)In this study, we maximize the energy savings of a hypothetical household by choosing an optimal insulation material with its optimal thickness and also the optimal window type. We develop a nonlinear mixed integer optimization model that maximizes the net present value of the benefits obtained by insulation over the lifespan of the house. Savings are calculated based on the gains from the electricity usage for air conditioning during cooling-required days and the fuel usage for heaters in heating-required days. The heat transfer calculations consider conductive, convective, and radiative components simultaneously. The optimization model takes the climate conditions of the region where the house is located, the consumer's desired indoor temperature, and the properties of the insulation options; then, it returns a combination of selected insulation materials with its optimum thickness and window type as output. We applied the optimization model developed to hypothetical houses in four different climatic regions of Turkey for different lifespans. For all reasonable lifespans, the model choses stonewool as the ideal insulation material. For high interest rates, single windows or double-glazed windows are preferable, but as the interest rate decreases and the net present value of the energy-savings increases, the model prefers triple-glazed windows as the ideal material. Erzurum, a city in climatic region 4, characterized by very cold winters and cool summers, was found to require the highest optimum insulation thickness, and the economic return resulting from the above-mentioned energy-saving actions was also found to be the highest in the case of Erzurum. In all the regions, the energy-saving investments were found to be feasible via applying the feasibility assessment techniques of net present value and payback period. The model developed in this study is applicable to any household as long as the required input data are available. Published by AIP Publishing.WOS:0004190002000332-s2.0-85038567088Science Citation Index ExpandedArticleUluslararası işbirliği ile yapılmayan - HAYIRKasımYÖK - 2017-1
Energy Investment Planning at a Private Company: A Mathematical Programming-Based Model and Its Application in Turkey
No full textSemra Ağralı (MEF Author)We consider a mid-sized private electricity generating company that plans to enter the market that is partially regulated. There is a cap and trade system in operation in the industry. There are nine possible power plant types that the company considers to invest on through a planning horizon. Some of these plants may include a carbon capture and storage technology. We develop a stochastic mixed-integer linear program for this problem where the objective is to maximize the expected net present value of the profit obtained. We include restrictions on the maximum and minimum possible amount of investment for every type of investment option. We also enforce market share conditions such that the percentage of the total investments of the company over the total installed capacity of the country stay between upper and lower bounds. Moreover, in order to distribute the investment risk, the percentage of each type of power plant investment is restricted by some upper bound. We tested the model for a hypothetical company operating in Turkey. The results show that the model is suitable to be used for determining the investment strategy of the company.WOS:0004132478000032-s2.0-85037056874Science Citation Index Expanded - Social Sciences Citation IndexArticleUluslararası işbirliği ile yapılmayan - HAYIRKasımYÖK - 2017-1
An optimization model for carbon capture & storage/utilization vs. carbon trading: A case study of fossil-fired power plants in Turkey
No full textSemra Ağralı (MEF Author)We consider fossil-fired power plants that operate in an environment where a cap and trade system is in operation. These plants need to choose between carbon capture and storage (CCS), carbon capture and utilization (CCU), or carbon trading in order to obey emissions limits enforced by the government. We develop a mixed-integer programming model that decides on the capacities of carbon capture units, if it is optimal to install them, the transportation network that needs to be built for transporting the carbon captured, and the locations of storage sites, if they are decided to be built. Main restrictions on the system are the minimum and maximum capacities of the different parts of the pipeline network, the amount of carbon that can be sold to companies for utilization, and the capacities on the storage sites. Under these restrictions, the model aims to minimize the net present value of the sum of the costs associated with installation and operation of the carbon capture unit and the transportation of carbon, the storage cost in case of CCS, the cost (or revenue) that results from the emissions trading system, and finally the negative revenue of selling the carbon to other entities for utilization. We implement the model on General Algebraic Modeling System (GAMS) by using data associated with two coal-fired power plants located in different regions of Turkey. We choose enhanced oil recovery (EOR) as the process in which carbon would be utilized. The results show that CCU is preferable to CCS as long as there is sufficient demand in the EOR market. The distance between the location of emission and location of utilization/storage, and the capacity limits on the pipes are an important factor in deciding between carbon capture and carbon trading. At carbon prices over $15/ton, carbon capture becomes preferable to carbon trading. These results show that as far as Turkey is concerned, CCU should be prioritized as a means of reducing nationwide carbon emissions in an environmentally and economically rewarding manner. The model developed in this study is generic, and it can be applied to any industry at any location, as long as the required inputs are available. (C) 2018 Elsevier Ltd. All rights reserved.WOS:0004307847000312-s2.0-8504410277029574208Science Citation Index ExpandedArticleUluslararası işbirliği ile yapılmayan - HAYIRHaziranYÖK - 2017-1
Dynamic Ambulance Deployment to Reduce Ambulance Response Times Using Geographic Information Systems: A Case Study of Odunpazari District of Eskisehir Province, Turkey
No full textAbstractBackground and ObjectiveAmbulances should always reach patients in the shortest time possible whenever they are called upon so as to increase patient survival chances especially in cardiac related medical cases. The placement of ambulances directly affects the time ambulances reach patients. The objective of the study was to find optimal stations to deploy ambulances so as to reduce ambulance response times and increase patient survival chances as a result.Data and MethodsTo reduce ambulance response times for Odunpazari district, the study employed system status management technique and maximal coverage location problem optimization model, to deploy ambulances according to ambulance demand and ensure maximum ambulance demand coverage is realized with a small ambulance fleet size, respectively. ArcGIS network analyst location allocation tool was used to find optimal ambulance stations from where ambulance demand areas can be reached within 5minutes of drive time. Four different ambulance deployment plans were modeled for periods ranging from 00:00 to 06:00hrs, 06:00 to 12:00hrs, 12:00 to 18:00hrs and 18:00 to 24:00hrs. The study used a total of 20,260 ambulance demand calls’ data for Odunpazari district collected from January 1st to December 31st 2014.ResultsThe Odunpazari district fleet of 17 ambulances was deployed differently for every six hours; between 00:00 to 06:00hrs, 06:00 to 12:00hrs, 12:00 to 18:00hrs and 18:00 to 24:00hrs to match ambulance demand and as a result, 77.6% of ambulance demand areas were located within 5minutes of drive time from the nearest ambulance station.ConclusionThe study found out that moving ambulances closer to ambulance demand areas reduces ambulance response times and dynamic ambulance deployment is by far a more effective ambulance deployment strategy than static ambulance deployment
Semra Ertan - Word and Body as Instruments of Socio-Political Protest
No full textThe bachelor thesis is dedicated to Semra Ertan, a poet and activist of Turkish origin, who lived since the 1970s with her parents in Germany, who worked there as guest workers (Gastarbeiter). In 1982, Ertan publicly set herself on fire in Hamburg. Although the publication of her poetry collection in 2020 aroused interest in both Germany and Turkey in her work and life's destiny, academic research is still lacking. The thesis aims to present the person and work of Semra Ertan as a topic that has not yet been researched. The student will first outline the development of the situation of the Turkish guest workers in Germany since the bilateral agreement between Germany and Turkey, introduce the author herself, and in the main part of the thesis will analyze her poems as such and the relationship between Semra Ertan's poems and her self-immolation. Thesis will try to answer the question of whether and how aspects of the author's life can be seen in her poems. To answer this question, in addition to the thematic analysis of the poems the approaches of the social contextual studies of literature as outlined by Josef Šebek will be used.Bakalářská práce je věnována Semře Ertan, básnířce a aktivistce tureckého původu, která žila od sedmdesátých let 20. století s rodiči v Německu, kteří zde pracovali jako hostující dělníci (Gastarbeiter). V roce 1982 se Ertan v Hamburku veřejně upálila. Přestože vydání její básnické sbírky v roce 2020 vzbudilo v Německu i v Turecku zájem o její tvorbu i životní osudy, odborné zpracování dosud chybí. Práce si klade za cíl představit osobu a dílo Semry Ertan jakožto téma v akademickém prostředí doposud nezpracované. Studentka nejprve nastíní vývoj situace tureckých pracovních sil v Německu od uzavření bilaterální smlouvy mezi SRN a Tureckem, představí samotnou autorku a v hlavní části práce pak bude analyzovat její básně jako takové a také vztah mezi básněmi Semry Ertan a jejím sebeupálením. Pokusí se odpovědět na otázku, zda a jakým způsobem lze v básních spatřovat aspekty autorčina života. K zodpovězení této otázky bude vedle tematické analýzy básní využívat přístupy sociálně kontextového studia literatury, jak je nastiňuje Josef Šebek.Department of Middle Eastern StudiesKatedra Blízkého východuFilozofická fakultaFaculty of Art
Influence de la cinétique d'hydratation des phases aluminates en présence de sulfate de calcium sur celles des phases silicates : conséquences sur l'optimum de sulfatage des ciments
No full textThe mechanical properties of hydrated cements need to be optimized according to the nature of cement products. Among the factors of optimization, the addition of calcium sulphate intended to regulate the reactivity of tricalcium aluminate (C3A), in quantity and quality in cement is an essential parameter.The advancement of knowledge on the mechanisms of hydration of each cement phase allows a study devoted entirely to the concept of optimum of sulphate. We studied simple system that we complicated and we studied the evolution of hydration, porosity and mechanical properties of cement at different age. The first system studied was the mixture C3S/gypsum, the objective was to determine whether there was an optimal effect of calcium sulfate on hydration and mechanical strength of C3S as presented in the literature [1]. The results showed there was not optimum sulfate in the C3S/gypsum system but there was a specific effect of calcium sulfate on the hydration and the mechanical properties of C3S. The sulfate adsorption on the C-S-H surface is the cause of the change nucleation and growth process of C-S-H. This has resulted in increasing hydration degree of C3S and compressive strength. The second system studied was biphasic clinker C3S/C3A ground with hemi-hydrate and gypsum. An optimum sulfate has been observed, which move out with time to high rate of sulfate. The optimum sulfate was observed when the hydration of C3S, during the accelerated period, takes place simultaneously or slightly before the exothermic peak due to the high dissolution of C3A and precipitation of AFm. We showed the presence of AFm during the accelerated hydration of C3S, is the cause of the microstructure modification in the cement paste: the porosity increases with calcium sulfate addition but the hydrate assembly is more dense.Les propriétés mécaniques des ciments hydratés nécessitent d'être optimisées suivant la nature des ciments produits. Parmi les facteurs d'optimisation, l'ajout de sulfate de calcium destiné à réguler la réactivité de l’aluminate tricalcique (C3A), en quantité et en qualité, dans le ciment est un paramètre primordial. Enjeu industriel majeur, cette notion d'Optimum de sulfatage mérite aujourd'hui du fait de l'avancement des connaissances sur les mécanismes d'hydratation de chacune des phases du ciment qu'une étude lui soit entièrement consacrée. La démarche adoptée pour répondre à cette problématique a été l’étude de système simple que l’on a compliqué petit à petit. L’évolution de l’hydratation du ciment, de la porosité et des propriétés mécaniques du ciment ont été déterminés à différentes échéances. Le premier système étudié était le mélange C3S/gypse, l'objectif était de déterminer s'il existait un effet optimal du sulfate de calcium sur l'hydratation et les résistances mécaniques du C3S tel que présenté dans la littérature [1]. Les résultats ont montré qu’il n’existait pas d’optimum de sulfatage dans le système C3S/gypse mais qu’il existait un effet spécifique du sulfate de calcium sur l’hydratation et les propriétés mécaniques du C3S. L’adsorption des sulfates à la surface des C-S-H serait à l’origine de la modification du processus de germination croissance des C-S-H qui aurait pour conséquence l’augmentation du degré d’hydratation du C3S et des résistances en compression. Le deuxième système étudié était le clinker biphasique C3S/C3A cobroyé avec du semi-hydrate et avec du gypse. Un optimum de sulfatage a bien été observé, cet optimum se décale avec le temps vers les fortes teneurs en sulfate comme dans les cimenteries. L’optimum de sulfatage a été constaté lorsque l’hydratation du C3S, pendant la période accélérée, a lieu simultanément ou légèrement avant le pic exothermique dû à la forte dissolution du C3A et à la précipitation d’Afm. Il a été montré que la présence d’AFm pendant la période accélérée de l’hydratation du C3S, serait à l’origine de la modification observée de la microstructure de la pâte de ciment : la porosité augmente avec l’ajout du sulfate de calcium mais l’assemblage des hydrates est plus dens
Influence of aluminates phases hydration in presence of calcium sulfate on silicates phases hydration : consequences on cements optimum sulfate
No full textLes propriétés mécaniques des ciments hydratés nécessitent d'être optimisées suivant la nature des ciments produits. Parmi les facteurs d'optimisation, l'ajout de sulfate de calcium destiné à réguler la réactivité de l’aluminate tricalcique (C3A), en quantité et en qualité, dans le ciment est un paramètre primordial. Enjeu industriel majeur, cette notion d'Optimum de sulfatage mérite aujourd'hui du fait de l'avancement des connaissances sur les mécanismes d'hydratation de chacune des phases du ciment qu'une étude lui soit entièrement consacrée. La démarche adoptée pour répondre à cette problématique a été l’étude de système simple que l’on a compliqué petit à petit. L’évolution de l’hydratation du ciment, de la porosité et des propriétés mécaniques du ciment ont été déterminés à différentes échéances. Le premier système étudié était le mélange C3S/gypse, l'objectif était de déterminer s'il existait un effet optimal du sulfate de calcium sur l'hydratation et les résistances mécaniques du C3S tel que présenté dans la littérature [1]. Les résultats ont montré qu’il n’existait pas d’optimum de sulfatage dans le système C3S/gypse mais qu’il existait un effet spécifique du sulfate de calcium sur l’hydratation et les propriétés mécaniques du C3S. L’adsorption des sulfates à la surface des C-S-H serait à l’origine de la modification du processus de germination croissance des C-S-H qui aurait pour conséquence l’augmentation du degré d’hydratation du C3S et des résistances en compression. Le deuxième système étudié était le clinker biphasique C3S/C3A cobroyé avec du semi-hydrate et avec du gypse. Un optimum de sulfatage a bien été observé, cet optimum se décale avec le temps vers les fortes teneurs en sulfate comme dans les cimenteries. L’optimum de sulfatage a été constaté lorsque l’hydratation du C3S, pendant la période accélérée, a lieu simultanément ou légèrement avant le pic exothermique dû à la forte dissolution du C3A et à la précipitation d’Afm. Il a été montré que la présence d’AFm pendant la période accélérée de l’hydratation du C3S, serait à l’origine de la modification observée de la microstructure de la pâte de ciment : la porosité augmente avec l’ajout du sulfate de calcium mais l’assemblage des hydrates est plus denseThe mechanical properties of hydrated cements need to be optimized according to the nature of cement products. Among the factors of optimization, the addition of calcium sulphate intended to regulate the reactivity of tricalcium aluminate (C3A), in quantity and quality in cement is an essential parameter.The advancement of knowledge on the mechanisms of hydration of each cement phase allows a study devoted entirely to the concept of optimum of sulphate. We studied simple system that we complicated and we studied the evolution of hydration, porosity and mechanical properties of cement at different age. The first system studied was the mixture C3S/gypsum, the objective was to determine whether there was an optimal effect of calcium sulfate on hydration and mechanical strength of C3S as presented in the literature [1]. The results showed there was not optimum sulfate in the C3S/gypsum system but there was a specific effect of calcium sulfate on the hydration and the mechanical properties of C3S. The sulfate adsorption on the C-S-H surface is the cause of the change nucleation and growth process of C-S-H. This has resulted in increasing hydration degree of C3S and compressive strength. The second system studied was biphasic clinker C3S/C3A ground with hemi-hydrate and gypsum. An optimum sulfate has been observed, which move out with time to high rate of sulfate. The optimum sulfate was observed when the hydration of C3S, during the accelerated period, takes place simultaneously or slightly before the exothermic peak due to the high dissolution of C3A and precipitation of AFm. We showed the presence of AFm during the accelerated hydration of C3S, is the cause of the microstructure modification in the cement paste: the porosity increases with calcium sulfate addition but the hydrate assembly is more dense
The effect of sound atmosphere on emotion from a travel motivation perspective
No full textTravel constitutes the dynamic structure of tourism. It is not possible to speak of tourism without travel activity. Since travel motivation is known as a psychological driver of a certain tourism behavior, it is extensively studied in tourism research. The travel motivations of people have changed in the historical course. Accordingly, a change is observed in the quality of the tourism market. It is important to know the changing travel motivations in order to survive in the tourism market where there is intense competition between businesses and destinations and to get more shares from the market. In this study, the effect of the soundscape of Fethiye city of Muğla, which is a medium-sized tourism destination in Turkey, on the mood of the tourists was examined within the framework of the travel motivation of the tourists. Within the scope of the study, a questionnaire was applied to 1320 tourists. The Positive and Negative Affect Schedule (PANAS) was used to measure the tourist\u27 moods. Moreover, there are also questions prepared to determine the travel motivations of tourists. It is known that the soundscape affects the relations of the tourists with the environment they are in and overall tourist satisfaction. From this point of view, in this study, it is suggested that the soundscape of tourism destinations should be kept under control and well-designed in order to ensure tourist satisfaction. In addition, determining the tourists’ travel motivation will be effective in the strategic decisions of the tourism stakeholders. In this direction, it is aimed to increase the quality of tourism service by offering suggestions to stakeholders, as well as to contribute to regional development and the national economy.
Keywords: soundscape, tourism, travel motivation, sustainable tourism
Seyahat motivasyonu perspektifinden ses atmosferinin duygu durumuna etkisi
Özet
Seyahat motivasyonu belirli bir turizm davranışını ortaya çıkaran psikolojik bir mekanizma olarak bilindiğinden turizm araştırmalarında yaygın olarak çalışılmaktadır. Tarihsel süreç içinde insanların seyahat motivasyonları değişim göstermiştir. Buna bağlı olarak da turizm pazarının niteliğinde de bir değişim gözlenmektedir. İşletmeler ve destinasyonlar arasında yoğun rekabetin yaşandığı turizm pazarında ayakta kalmak ve pazardan daha fazla pay almak için değişen seyahat motivasyonlarının bilinmesi önem arz etmektedir. Bu çalışmada, Türkiye’deki orta büyüklükte bir turizm destinasyonu olan Muğla’nın Fethiye şehrine ait ses atmosferinin turistlerin duygu durumuna etkisini turistlerin seyahat motivasyonu çerçevesinde incelenmiştir. Araştırma kapsamında, 1320 turiste anket uygulanmıştır. Turistlerin duygu durumunu belirlemek amacıyla Pozitif ve Negatif Duygu Ölçeği (PNDÖ) kullanılmıştır. Ayrıca turistlerin seyahat motivasyonlarının belirlenmesi amacıyla hazırlanmış sorular da bulunmaktadır. Ses atmosferinin turistlerin içinde bulundukları ortamla olan ilişkilerini ve genel turist memnuniyetini etkilediği bilinmektedir. Buradan hareketle turist memnuniyetinin sağlanması için bu çalışmada turizm destinasyonlarının ses atmosferinin kontrol altında tutulması ve iyi dizayn edilmesi gerektiği önerilmektedir. Ayrıca, turistleri seyahate yönelten motivasyonlarının belirlenmesi turizm paydaşlarının alacakları stratejik kararlarda etkili olacaktır. Bu doğrultuda paydaşlara öneriler sunarak turizm hizmet kalitesinin artırılmasının yanı sıra bölgesel kalkınma ve ulusal ekonomiye katkı sağlanması hedeflenmektedir.
Anahtar Kelimeler: ses atmosferi, turizm, seyahat motivasyonu, sürdürülebilir turiz
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