Graduate Schools - Theses

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This collection of Bilkent University Theses in BUIR contains selected theses and dissertations from all Bilkent University departments.

Bilkent University's DSpace contains more than 6000 theses completed at Bilkent dating as far back as the mid 1980's. Theses in this collection have been scanned by Technical Services or submitted in electronic format by thesis authors.

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Open Access
1-GO 1-E: the development of durational aesthetics in mixed media sculpture
(2020-06) Teğin, Alp E.
This thesis investigates the development of a technique for the depiction of motion in painting through mixed media sculpture. Utilizing stacked glass layers as the spatial medium, 1-Go 1-E conceptualizes the technique utilized in the creation of barrier grid animations to be used in painting. Examining the concept of movement through the composite of Henri Bergson’s conception of qualitative and quantitative multiplicities, this thesis merges both to create a workflow for the creation of stacked glass mixed media sculptures.
Open Access
15 yüzyıldan 18 yüzyıla kasidelerde ideal hükümdar portresi ve hükümdarın metaforik sunumu
(2013) Onay, Ebru
Originated from the question how the sovereignty of sultan affected and shaped the mind of “Homo-Ottomanicus”, this project focuses on the portrayal of the Ottoman sultans in qasidas in general and the metaphorical presentation of them in particular. With a specific emphasis on the importance of the perspectives qasidas can provide for the research, a number of qasidas written for the reigning sultan by Ahmad Pasha, Bâkî, Nef’î, and Nedîm in their Turkish divans have been examined in the thesis. It is observed that in qasidas the sultan is generally depicted as fair, generous, benign, and good warrior and this feature was a result of the circle of equity inherited from Persian- Arabic- Indian ruling tradition -or rather an idiosyncratic amalgamation of them. With a specific eye to the functions of the comparisons and analogies between the Ottoman sultans and heroes from Persian and Islamic mythologies, the importance of comparisons and analogies in strengthen of the power of the sultans is discussed. This being done, I attempt to examine the metaphorical presentation and representation of the Ottoman sultans in selected qasida examples from aforementioned poets. In this main part, George Lakoff and Mark Johnson’s influential work on metaphor, Metaphors We Live By, is applied as theoretical frame. Lakoff and Johnson assert that metaphors are not merely simple linguistic devices to add some aesthetic value to our statements and literary expressions but rather an intrinsic component of our cognitive process, hereby, could provide us an elusive resource to get a better understanding of mind, and the ways it functions. On the bases of this argument, the metaphorical employment of the language in selected qasidas are examined to get the climate of mind in terms of the relationship between sultans and their subjects in the Ottoman Empire. It has been observed that in concerning qasidas from four divans, the sultan is generally portrayed as “aloft” and “ahead” while the subject is portrayed as “beneath” and “behind”. Furthermore, the sultan is depicted in these poems as a “shadow” offers protecting, “a sanctuary” to take refuge in, and an “aesthetic creature” or an “ornament” with the power to embellish its surroundings. The frequency of using these metaphors is changing over the concerning periods whereas in Nedîm’s Divân the number of the “ornament metaphors” for the sultan increases significantly compared to the other three divans. After discussing the possible reasons and meaning of this turn in metaphorical employment, the project compares its findings with the conventional arguments regarding the Ottoman sultans in European centred readings. It is claimed that as the representative of authority and power, the Ottoman sultan is depicted contradistinctively as “protector-shelter” in qasidas rather than as “the despotic father” that the European centred readings have claimed him to be so far.
Open Access
19 yüzyıl Osmanlı basınındaki belagat tartışmaları ışığında edebiyatın dönüşümü
(2013) Dilek, Esra Derya
This study is an attempt to analyse the rhetorical argumentation style in the last quarter of the 19th century with consideration to influences on the literary style of the period. Studies on rhetoric more often than not have focused on langauge-related aspects, while the link between rhetoric and literature has been disregarded. Consequently, rhetoric as a literary discourse has been limited to discussions on language and alphabet. The formation of an authentic national rhetoric is influenced by both old and new literary traditions. The encounter with the West from the 18th century not only caused social change but also brought changes to the literary tradition. One such change was the idea of separating Ottoman rhetoric from its Arabic counterpart. In this manner, rhetoric came to embody a new literary style by eliminating previous lingual and literary discourses. Thus, the significance of discussions on rhetoric in literary circles is the main focus of this study. In the first section of this study, the history of Ottoman rhetoric, the relationship between rhetoric and literature, and finally, the rhetoric of Ottoman literature are examined. The second chapter focuses on particular periodicals, namely Tercümân-i Hakîkat, Cerîde-i Havâdis, Vakit and Tarîk. An analysis is undertaken of certain literary stylistic changes featured in these periodicals. The last section of this study examines the reformation period and its impact on Ottoman literature and literary discussions.
Open Access
19 yüzyıl Osmanlı-Türk edebiyatında öykü
(2008) Aydın, Hilal
In this study, the works Letaif-i Rivayat by Ahmet Mithat (1844-1912), Müsameretname by Emin Nihat (?), Küçük Şeyler by Samipaşazade Sezai (1860- 1936), and Karabibik by Nabizâde Nazım (1862-1893), which all have a number of aspects in common and are considered by Ottoman-Turkish short story critics to be among the first examples of the genre, will be examined by means of close reading, by interpretation of the effects of extra-literary conditions, and in comparison with Eurocentric approaches to the short story. In the critical writings on the above short stories that were produced in the post-Tanzimat era, allegations of imitation similar to those directed at the novels of the same era were put forward. A short story standard defined by Western literatures has been introduced into Ottoman-Turkish literature as the ideal formula. As a result of this approach, when the works in question are found to contain any aspects that do not fit such criteria, they are harshly denounced for their lack of skill, of competence, and of sense. However, as will be demonstrated in the second chapter of the study, there is in fact little agreement about the criteria themselves, as they continue to be debated and criticized from a variety of perspectives even within the context of Western literature. Nonetheless, quite dramatically, such criteria have been established as an unshakable foundation in Turkish short story criticism. A number of problems, particularly the classification of the genre, arise within this Eurocentricoriented critical approach insofar as such an approach neglects these works’ local background and the unique circumstances under which they were produced. In addition to the above considerations, this study aims to point out certain basic deficiencies detectable in previous criticism, such as the insufficient emphasis on the difference between the short story as a genre and narration as a means of expression. The study will also attempt to emphasize, in regard to the writing of the literary history of the Ottoman-Turkish era, the importance of defining these preliminary examples of the genre as well as their interactions and changes, and thus aims to underline the significance of these works’ local background as against the Western criteria forced upon them in previous criticism. Bearing in mind all of the above considerations concerning the Eurocentric critical approach and its deficiencies, the last chapter of the study will focus on the short stories themselves, and the data collected from these works will be interpreted inductively in an attempt to emphasize the idea of the locality and originality of Ottoman-Turkish literature. Ultimately, it will be shown that, unlike the general suppositions made in previous criticism, the aim of the writers of these short stories was not mere imitation, and that even the alleged Western influences on these works were reshaped and transformed in accordance with the uniqueness of the texts. Consequently, the study aims to contradict previous approaches, which support the idea that the short story, as a genre, originated wholly in Western literature.
Open Access
19 yüzyıl Osmanlı-Türk romanında gayrimüslim imgeleri
(2007) Uyanık, Seda
This thesis aims at exploring the changing images of non-Muslim characters in five novels written in the last quarter of the 19th century, namely Karabibik (1891) by Nabizade Nazım; Turfanda mı Yoksa Turfa mı? (1892) by Mizancı Mehmet Murat, Araba Sevdası (1896) by Recaizade Mahmut Ekrem, Mes‚il-i Muğl‚ka (1898) by Ahmet Mithat Efendi and Aím‚k-ı Hayal (1910) by Şehbenderz‚de Filibeli Ahmet Hilmi. The novels are discussed taking the historical background and the authorsí ideological positioning into consideration. Reviews and critical essays focusing on non-Muslim characters in novels during the post-Tanzimat period are limited in number and scope and are based on generalizations that do not recognize the various authorsí intellectual and ideological particularities and differences. The study of the five novels examined in this thesis shows that there are several differing images of non-Muslim characters. The image and role of nonMuslim characters in the works depend on the authors approach to religion, ethnical identity and his understanding of civilization. The highlighting of differences between European and Muslim cultures in those novels leads to the positioning of the non-Muslim image in a circle of ìidentity and differencesî. The focus on nonMuslim characters in those novels, shows that the concepts of religion, nation and culture have close links to typological structures such as modernity and tradition, centre and periphery and ìIî and the other. In the light of this study, it is concluded that it is not possible to talk about only one single non-Muslim concept in the postTanzimat novels
Open Access
19 yüzyılda Osmanlı toplumu ve basılı Türkçe edebiyat : etkileşimler, değişimler, çeşitlilik
(2009) Ayaydın Cebe, Günil Özlem
This dissertation is built on the proposition that the majority of literary histories hitherto written on 19th century Ottoman Turkish literature reflects a very limited part of the object of investigation, selected generally according to non-literary criteria. Consequently, it is asserted that most of the research and examination relying on these sources is inadequate in comprehending the true nature of Ottoman literary universe. In this study, in order to overcome this problem of short-sightedness about the object of investigation, it is deemed necessary to depict an accurate map of printed literary texts in Turkish and focus on the medium that creates literature. To achieve this, a database is formed comprising bibliographic data on texts printed in Turkish in Arabic, Armenian and Greek letters between the years 1800-1900, and a new method of classification and counting is developed according to the specific needs of the material collected. Afterwards, the chronological trends of literary genres and their production in ratios are revealed. Through this, various tools are created for questioning set periodizations and fixed judgements about the field. By interpreting these tools in tandem with the historical, political and socio-cultural developments of the era, and in comparison to literature in manuscript form, the following main observations and conclusions, among others, are made: First, it is demonstrated that literature is the key field to understanding the modernization venture of the Ottoman Empire. Secondly, it is observed that there had been a closer literary interaction and exchange among the Muslim and nonMuslim communities of the Empire than that is supposed in contemporary assumption. Thirdly, it is found out that the advancements in printing and publishing caused a dramatic shift from oral and written culture to print culture that gave rise to social and literary transformations. Lastly, the effects of this transformation on classical, traditional and modern literary forms are discussed, and fresh areas of research are presented.
Open Access
19. yüzyıl cep romanlarının beden-zihin denetimi ve romantik ilişkilenme biçimleri açısından modernleşmedeki yeri
(2019-09) Sezen, Güneş
Bu tez, 19. yüzyıl sonunda yeni bir format olarak ortaya çıkan cep romanlarının, Arakel ve Şems kitapçıları tarafından basılan örneklerinde iktidar söylemleri ile kurmaca arasındaki ilişkileri incelemektedir. Yeni Tarihselci perspektifin benimsendiği bu çalışma, 19. yüzyılın modern ailesini oluşturan “yeni insanının,” kadınlık ve erkekliklerinin nasıl inşa edildiğine odaklanmıştır. Osmanlı’nın özellikle son yüzyılında artan modernleşme endişesi, hukukî ve toplumsal açıdan bazı düzenlemelerin önünü açarken, sağlık ve nüfus politikalarını da şekillendirmiştir. Asrın sonunda Arakel öncülüğünde yeni bir türsel format olarak ortaya çıkan cep romanları, bu tarihsel seyrin izlenebildiği, önemli kurmaca örnekleridir. Cep romanları, çoğunlukla döneminin en velûd ve talep gören yazarları tarafından yazılmalarına rağmen edebiyat eleştirisi ve tarihlerinde yer bulamamıştır. Bu çalışmada romantik ilişkilere odaklanan cep romanları, olumlu ve olumsuz beden temsilleri bakımından mercek altına alınmaktadır. Satış stratejileri ve eğlendirerek okutma gayreti, cep romanlarının hem biçimine hem de içeriğine etki etmiştir. Bu romanlar, asır sonunda görünürlüğü artan gayrimeşru ilişkiler, frengi, kürtaj, histeri, obsesyon, cinnet, intihar, alkol kullanımı gibi zihinsel ve bedensel “bozulmaların” kontrolü ve disiplini için birer araç olarak konumlandırılmıştır. Bu nedenle, bu “toplum mühendisliği metinleri,” her an her yerde okunabilme pratikliklerine dayanarak, modern Osmanlı ailesinin imkânlarını ve farklı kadınlık ve erkekliklerin kamusal alanda nasıl kurulduğunun tartışılabilmesine olanak sağlamaktadırlar.
Open Access
The 1912 Galata Bridge as a site of collective memory
(2002) Şumnu, Umut
This work looks at the 1912 Galata Bridge as a case study and attempts to examine it as a dual construction in two senses: space and memory. Acknowledging that space and memory mutually construct each other, this thesis explains each term in general but also elucidates the relationship between perception and remembrance of space by reading the materiality of the 1912 Galata Bridge. In that respect, changing meanings attributed to space over time are analysed lead us to recognise two different ways of conceiving space named as 'spaceness' and 'placeness'. This dual existence is conductive to raising questions about perception of the 1912 Galata Bridge in two layers. Taken separately, its function of conveyance and the property of inhabitation lead us to read 'spaceness' and 'placeness' that also correspond to two ways of remembering it. Its 'spaceness' is perceived by the gaze and remembered through looking at its images, its 'placeness, on the other hand, is experienced by the body and recollected through reading texts that describe the actual engagement. Hence, 'spaceness' and 'placeness', gaze and body, image and text are correspondingly related with each other by the agency of the 1912 Galata Bridge as situated in collective memory.
Open Access
1950'ler Türkiye'sinde edebiyat dergiciliği : poetikalar ve politikalar
(2007) Uçar, Aslı
This study sought to answer the question of how Turkish literary journalism affected the conditions of literary production and consumption in the 1950s. The first chapter is devoted to the survey of literature and methodological issues. According to the method specified in the first chapter, the second chapter gives comparative analysis of the poetics of five different literary magazines, namely Hisar, Mavi, Pazar Postası, Varlık and Yeditepe published in the 1950s, in order to demonstrate their specific contributions to the protection and tranformation of literary values. Since inter-journalistic relations was one of the main characteristics of the period, the third chapter deals with the relations between the magazines and literary debates on which they focused. Two conceptual frameworks indirectly related to the study of literary magazines—Jürgen Habermas’ and Hannah Arendt’s notion of “public sphere” and Bourdieu’s “field of cultural production”—have been discussed and criticized according to the empirical evidence that has been drawn from the 1950’s literary journalism. In conclusion, it is asserted that inter-journalistic relations in the 1950s—ranging from consensus to conflicts—helped literary magazines to define poetics that enabled them to fuel literary production and consumption.
Open Access
1960s Turkey from the perspective of the Peace Corps volunteers
(2023-08) Ünal, Muhammed
This thesis aims to examine the memoirs and interviews of the Peace Corps volunteers who served in Turkey to display their image of Turkey in the 1960s. Peace Corps was active in Turkey from 1962 to 1971. Peace Corps Turkey volunteers served in every region of the country in villages, towns, and cities. They lived and worked with Turkish people for two years. Thus, they had an intimate first-hand experience and interesting observations about various topics. This thesis will argue that the volunteers viewed Turkey with the outlook of modernization theory. They observed a country that needed development and modernization. They noticed the traditional gender roles and gender separation in Turkish society. Turkish women needed to overcome these difficulties to modernize. They also noted the underdevelopment of infrastructure and healthcare system as major hindrances. They commented that the Turkish government worked hard to modernize the country, but there was some resistance to its efforts by the Turkish people.
Open Access
2-18 GHZ MMIC distributed amplifiers
(1994) Ergun, Sanlı
Using GaAs Monolithic Microwave Integrated Circuit (MMIC) technology three distributed amplifiers are realized. Two of these amplifiers employ single gate FETs and operate in the 2-18 GHz frequency range. They have 4.5 and 6.5 dB gain, respectively. The third amplifier utilizes cascode connected FETs. This amplifier operates in the 2-20 GHz range and has a gain of ~10 dB. All the three amplifiers have input and output return losses better than 10 dB. The isolation of the amplifiers with single gate FETs is better than 20 dB, whereas the cascode connection improves the isolation over 30 dB. The amplifiers are designed for a 50O-svstem. The simulations are made linearly, and the results match the theoretical work. In the design of these amplifiers a more detailed method is used in which the artificial transmission lines are investigated and optimized in their frequency behaviour. Besides, to realize these amplifiers, a new parametrized cell library for GEC-Marconi’s F20 foundry process is created and utilized.
Open Access
2-fold structures and homotopy theory
(2023-01) Haderi, Redi
It is well-known that correspondences between categories, also known as profunctors, serve in classifying functors. More precisely, every functor F : X → A straightens into a lax mapping χF : A → Catprof from A into a 2-category of categories and profunctors ([45]). We give a conceptual treatment of this fact from the lens of double category theory, contending the latter to be most natural environment to express this result. Then we venture into the world of simplicial sets and prove an analogous theorem. The notion of correspondence is easy to extend to simplicial sets, but a suitable double category may not be formed due to the lack of a natural tensor product. Nonetheless, we show that there is a natural simplicial category structure once we invoke higher correspondences. In proving our result we extend some notions from double category theory into the world of simplicial categories. As an application we obtain a realization of Lurie’s prediction that inner fibrations are classified by mappings into a higher category of correspondences between ∞-categories.
Open Access
The 2011 Libyan Civil War: From the four-decade Qaddafi rule to the French-led NATO intervention
(2016-01) Yaycı, Fatma
This thesis aims to investigate the exceptional case of the 2011 Libyan civil war, in which both a revolution and a foreign intervention took place, from a historical perspective based mainly on qualitative content analysis. In this regard, this thesis takes a deeper look at the events unfolding in Libya before and after the crisis erupted as well as analyzes the internal reasons behind the uprising and then its evolution into a civil war, the limits and excesses of the international response to the crisis in Libya within the context of the „responsibility to protect‟ doctrine and its possible future uses, and lastly, the way in which France was involved in the Libyan civil war and how the French national interests curtailed the Libyan peoples‟ efforts for a true revolution.
Open Access
3+1 Essays on the Turkish economy
(2005) Yücel, Mustafa Eray
This dissertation comprise of four essays. The first essay studies the relationship between treasury auction maturity and auction interest rates. Using the Turkish auction data from 1988 to 2004, a reciprocal linkage between auction interest rates and maturities is observed, especially for the 1995-2000 period. This suggests that under an adverse shock, treasury decreases the auction maturity in order not to increase interest rates too much. A change in this reciprocal relationship is also reported for the post-2001 era. The second essay assesses the effect of USD-Euro parity on a small open economy for an economy where its exports are predominantly denominated in Euros and imports are denominated in USD. The empirical evidence suggests that a positive innovation in USD-Euro parity appreciates the local currency, decreases inflation and increases output. The third essay studies the relationship between on-budget and off-budget expenditures in Turkey and concludes that information content of the budget deficit statistics is not empty; however, it might be misleading in assessing fiscal stance for Turkey. The final essay investigates the connection between Turkish industrial production performance and the success of a popular Turkish football team, namely Fenerbahce. The success of Fenerbahce is interpreted as a proxy for the workers' mood or morale. Performing a transfer function analysis on my monthly data set, I reveal a positive feedback from Fenerbahce's success, which proxies workers' mood/morale, to economic performance. Evidence of the effects of games against domestic rivals on industrial performance is not statistically significant.
Open Access
3-dimensional median-based algorithms in image sequence processing
(1990) Alp, Münire Bilge
This thesis introduces new 3-dimensional median-based algorithms to be used in two of the main research areas in image sequence proc(',ssi,ng; image sequence enhancement and image sequence coding. Two new nonlinear filters are developed in the field of image sequence enhancement. The motion performances and the output statistics of these filters are evaluated. The simulations show that the filters improve the image quality to a large extent compared to other examples from the literature. The second field addressed is image sequence coding. A new 3-dimensional median-based coding and decoding method is developed for stationary images with the aim of good slow motion performance. All the algorithms developed are simulated on real image sequences using a video sequencer.
Open Access
33 Femtosecond Yb-doped optical frequency comb for frequency metrology applications
(2013) Şenel, Çağrı
Optical frequency combs have enabled many applications (high precision spectroscopy, table-top optical frequency metrology, optical atomic clocks, etc.), received considerable attention and a Nobel Prize. In this thesis, the development of a stabilized Yb-doped femtosecond optical frequency comb is presented. As a starting point in the development of the frequency comb, a new type of fiber laser has been designed using numerical simulations and realized experimentally. The developed laser is able to produce pulses that can be compressed to 33 fs without higher-order dispersion compensation. After realization of the laser, a new type of fiber amplifier has been developed to be used for supercontinuum generation. The amplifier produces 6.8 nJ pulses that can be compressed to 36 fs without higher-order dispersion compensation. The dynamics of supercontinuum generation have been studied by developing a separate simulation program which solves the generalized nonlinear Schr¨odinger equation. Using the simulation results, appropriate photonic crystal fiber was chosen and octave-spanning supercontinuum was generated. Carrier-envelope-offset frequency of the laser has been obtained by building an f-2f interferometer. Repetition rate and carrier-envelope offset frequency of the laser have been locked to Cs atomic clock using electronic feedback circuits, resulting in a fully stabilized optical frequency comb. The noise performance and stability of the system have been characterized. Absolute frequency measurement of an Nd:YAG laser, which was stabilized using iodine gas, has been performed using the developed optical frequency comb.
Open Access
360-degree feedback : the influence of perceptions of organizational culture on upward appraisal system attitudes
(2003) Yalçın, Murat
At the threshold of the 21st century, organizations have reinterpreted organizational achievement factors for employees and they have started to emphasize the importance of human resources more in their organizational activities. Moreover, human resources have become a global competition element for organizations in their institutional environments. For that reason, organizations have to manage their human resources in a better way to motivate their employees and to drive their energy into organizational achievement. It is also necessary and critical to evaluate properly the performance of employees for various human resource practices such as promoting, compensating, etc. In other words since organizational achievement can be considered as a synergic sum of individual efforts, performance appraisal for improvement purpose is crucial for such an organisation. Ie army organization. The way that an organization measures and evaluates individual employee performance will directly effect organizational achievement. Therefore, evaluation results should reflect the factual evidences about the performance of organizations at the unitary level. To produce iii objective appraisal results, it is necessary to combine evaluations of all stakeholders involved in the process. It is also important to have positive perception of organization wide on the appraisal methods. This study discusses 360-degree feedback and upward appraisal systems that provide supervisors the opportunity to increase their self-awareness. This will also help them to improve their leadership conducts by having feedback from various sources. The system will also increase individual commitment of subordinates by giving them chance to express their opinions about supervisors, and thus, to participate more in the decision making process which is likely to create a higher level of motivation. However if organizations try to implement 360-degree feedback or upward appraisal system without studying the organizational culture, their effort may be futile. This thesis aims at identifying attitudes toward 360-degrees feedback and upward appraisal systems. It also tries to provide a general profile of organizational climate for Turkish Army through perceptions of Army officers.
Open Access
3D dynamic modeling of spherical wheeled self-balancing mobile robot
(2012) İnal, Ali Nail
In recent years, dynamically stable platforms that move on spherical wheels, also known as BallBots, gained popularity in the robotics literature as an alternative locomotion method to statically stable wheeled mobile robots. In contrast to wheeled platforms which do not have to explicitly be concerned about their balance, BallBot platforms must be informed about their dynamics and actively try to maintain balance. Up until now, such platforms have been approximated by simple planar models, with extensions to three dimensions through the combination of decoupled models in orthogonal sagittal planes. However, even though capturing certain aspects of the robot’s motion is possible with such decoupled models, they cannot represent inherently spatial aspects of motion such as yaw rotation or coupled inertial effects due to the motion of the rigid body. In this thesis, we introduce a novel, fully-coupled 3D model for such spherical wheeled balancing platforms. We show that our novel model captures important spatial aspects of motion that have previously not been captured by planar models. Moreover, our new model provides a better basis for controllers that are informed by more expressive system dynamics. In order to establish the expressivity and accuracy of this new model, we present simulation studies in dynamically rich situations. We use circular paths to reveal the advantages of the new model for fast maneuvers. Additionally, we introduce new inverse-dynamics controllers for a better attitude control and investigate within simulations the capability of sustaining dynamic behaviors. We study the relation between circular motions in attitude angles and associated motions in positional variables for BallBot locomotion.
Open Access
3D electron density estimation in the ionosphere by using IRI-Plas model and GPS measurements
(2016-05) Tuna, Hakan
Three dimensional imaging of the electron density distribution in the ionosphere is a crucial task for investigating the ionospheric effects. Dual-frequency Global Positioning System (GPS) satellite signals can be used to estimate the Slant Total Electron Content (STEC) along the propagation path between a GPS satellite and ground based receiver station. However, the estimated GPS-STEC are very sparse and highly non-uniformly distributed for obtaining reliable 3D electron density distributions derived from the measurements alone. Standard tomographic re- construction techniques are not accurate or reliable enough to represent the full complexity of variable ionosphere. On the other hand, model based electron density distributions are produced according to the general trends of the iono- sphere, and these distributions do not agree with measurements, especially for geomagnetically active hours. In this thesis, a novel regional 3D electron density distribution reconstruction technique, namely IONOLAB-CIT, is proposed to as- similate GPS-STEC into physical ionospheric models. The IONOLAB-CIT is based on an iterative optimization framework that tracks the deviations from the ionospheric model in terms of F2 layer critical frequency and maximum ionization height resulting from the comparison of International Reference Ionosphere ex- tended to Plasmasphere (IRI-Plas) model generated STEC and GPS-STEC. The IONOLAB-CIT is applied successfully for the reconstruction of electron den- sity distributions over Turkey, during calm and disturbed hours of ionosphere using Turkish National Permanent GPS Network (TNPGN-Active). Reconstruc- tions are also validated by predicting the STEC measurements that are left out in the reconstruction phase. The IONOLAB-CIT is compared with the real ionosonde measurements over Greece, and it is shown that the IONOLAB-CIT results are in good compliance with the ionosonde measurements. The results of the IONOLAB-CIT technique are also tracked and smoothed in time by using Kalman filtering methods for increasing the robustness of the results.
Open Access
A 3D garment design and simulation system
(2004) Durupınar, Funda
In this thesis study, a 3D graphics environment for virtual garment design and simulation is presented. The proposed system enables the three dimensional construction of a garment from its two dimensional cloth panels, for which the underlying structure is a mass-spring model. Construction of the garment is performed through cutting, boundary smoothing , seaming and scaling. Afterwards, it is possible to do fitting on virtual mannequins like in the real life as if in a tailor’s workshop. The behavior of cloth under different environmental conditions is implemented applying a physically-based approach. As well as the simulation of the draping of garments, efficient and realistic visualization of garments is an important issue in cloth modelling. There are various material types and reflectance properties for fabrics. We have implemented a number of material and rendering options such as knitwear, woven cloth and standard shading methods such as Gouraud shading. Performance results of the system are presented at the end.

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