Aygıtların elektriksel ve kimyasal analizleri için X-Işını fotoelektron spektroskopisinin sıvı/katı arayüzeylerini de kapsayacak şekilde genişletilmesi

Cataloged from PDF version of article.Thesis (Ph.D.): Bilkent University, Department of Chemistry, İhsan Doğramacı Bilkent University, 2018.Includes bibliographical references (leaves 98-115).Understanding of electrical and electrochemical devices in operating conditions is vital for development of new technologies. Many important characteristics that determine the performance of such devices lie on their surfaces and interfaces which significantly deviate from the bulk properties. However, particularly for the liquid based devices, carrying out surface analysis is challenging and requires highly sophisticated instrumentation. In this PhD. thesis, we aim to unravel the potential development on liquids, dielectrics as well as the liquid/solid interfaces during AC and DC excitation in a chemically resolved fashion using the UHV compatible non-aqueous liquids in a basic electrowetting on dielectrics configuration within X-Ray Photoelectron Spectroscopy (XPS) chamber. Low molecular weight Polyethylene glycol (PEG) and a particular ionic liquid Diethylmethyl(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide [DEME][TFSI] are used to represent two extreme cases as being non-ionic and fully-ionic liquids. Application of external electrical bias to these devices either from the top or the bottom electrode during data acquisition enabled us to investigate the electrowetting phenomenon, in a chemically addressed fashion In the first part of the thesis, geometrical changes that the drop undergoes during electrowetting have been monitored both by steady state areal maps and by dynamic XPS point analysis where the potential was altered periodically. In the second part, we have focused only on the DC electrowetting of liquids. We probed the potential developments in the dielectric layer and on the liquid by monitoring the changes in the binding energy of the representative XPS peaks with respect to the applied potential. We showed that the conductivity of the liquid has no influence on the potential and the entire potential drop occurs at the liquid/dielectric interface. Dielectric breakdown and its effect on the potential developments were also investigated in this part. In the third part, we have tried to understand the frequency dependent potential developments of the ionic liquid and the polyethylene glycol based EWOD devices by AC electrowetting. Our time dependent XPS measurements under AC excitation with sweeping frequency have demonstrated that EWOD devices exhibit two different behaviors separated by a critical frequency, which is dependent on the AC resistance (impedance) or ionic content of the liquid and also the electrical characteristics of the dielectric layer. Below the critical frequency, XPS spectra are mainly affected by the capacitive component of the dielectric, hence the liquid completely screens the applied electrical field. However, for frequencies above the critical, the resistive component of the liquid dominates and the drop behaves like a resistive strip, resulting in the formation of equipotential surface contours which are shown experimentally for the first time in this study. In the last part of the thesis, an equivalent circuit model was developed to electrically describe the electrowetting behavior of PEG on dielectric and also to generate a solid-state mimicking device to produce the same XPS spectral observations.by Pınar Aydoğan Göktürk.Ph.D

Eş zamanlı hesaplama ve veri yükü dengeleme için çizge/hiperçizge bölümleme modelleri

Cataloged from PDF version of article.Thesis (M.S.): Bilkent University, Department of Computer Engineering, İhsan Doğramacı Bilkent University, 2018.Includes bibliographical references (leaves 57-64).In the literature, several successful partitioning models and methods have been proposed and used for computational load balancing of irregularly sparse applications on distributed-memory architectures. However, the literature lacks partitioning models and methods that encode both computational and data load balancing of processors. In this thesis, we try to close this gap by proposing graph and hypergraph partitioning models and methods that simultaneously encode computational and data load balancing of processors. The validity of the proposed models and methods are tested on two widely-used irregularly sparse applications: parallel mesh simulations and parallel sparse matrix sparse matrix multiplication.by Mestan Fırat Çeliktuğ.M.S

Kanada ve Türkiye için devlet aktörler ve uluslararası krizin iltica politikası üzerine etkileri

Cataloged from PDF version of article.Thesis (Ph.D.): Bilkent University, Department of Political Science and Public Administration, İhsan Doğramacı Bilkent University, 2018.Includes bibliographical references (leaves 131-143).Over the last 25 years, the literature suggests that asylum policies in industrialized countries have become increasingly restrictive and selective. Although there is academic debate, particularly in connection with security studies, presently accepted definitions of ‘refugee’ and ‘asylum’ tend to be informed by the Convention and its creation in response to movement of people coming out of devastating conflict. This research examines six influential factors identified as affecting the implementation of asylum policy within four different historical cases of refugee influx stemming from international conflict: Canada and Turkey, 1988-1992 and 2001-2005. It uses a new method, ADVIAN classification, to analyze non-linear relationships amongst factors to understand which are the most active, passive, and critical, and how the factors interact as a system. This research uses data from the study of primary historical documents and information from elite interviews. By understanding the relationships and status of each factor within the system, this research contributes to understanding asylum policy as comparative systems and identifies common interactions amongst factors across diverse cases.by Christina Hamer.Ph.D

Zaman serilerinde birim kök testleri üzerine makaleler

Cataloged from PDF version of article.Thesis (Ph.D.): Bilkent University, Department of Economics, İhsan Doğramacı Bilkent University, 2018.Includes bibliographical references (leaves 106-108).This dissertation consists of three essays which develop new unit root testing methods in time series. First one is about the effect of the persistent volatility breaks, i.e. non-stationary volatility, on the unit root inference in regulated time series. In this essay, we show that conventional bounded unit root tests become potentially unreliable in the presence of the non-stationary volatility. Then, as a remedy, we propose a new class of unit root tests that are robust to both the range constraints and the permanent volatility shifts present in the time series. While developing our new tests, we also extend the asymptotic theory for integrated time series. The second essay is about testing for seasonal unit roots. In this essay, we first construct a family of nonparametric seasonal unit root tests by utilizing fractional integration operator. Different from the wellknown parametric seasonal unit root tests, the proposed tests are free from tuning parameters. Another contribution of this essay is on the fractional integration literature. We introduce a new fractionally transformed seasonal series. The third essay deals with the effect of the heteroscedastic innovations on the nonparametric seasonal unit root tests. We demonstrate that these tests spuriously reject the true seasonal unit root null hypothesis under the heteroscedasticity. To remove the aforementioned size distortions, we develop nonparametric wild bootstrap seasonal unit root tests. These tests are successful in correcting size problems under a broad class of heteroscedasticity observed in the seasonal time series. Moreover, we show that the proposed tests are asymptotically pivotal.by Kemal Çağlar Göğebakan.Ph.D

Opera için atan bir kalpten uluslararası sahnelere Türk yetenek : Suna Korat

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2018.This work is a student project of the Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.The History of Turkey course (HIST200) is a requirement for all Bilkent undergraduates. It is designed to encourage students to work in groups on projects concerning any topic of their choice that relates to the history of Turkey. It is designed as an interactive course with an emphasis on research and the objective of investigating events, chronologically short historical periods, as well as historic representations. Students from all departments prepare and present final projects for examination by a committee, with 10 projects chosen to receive awards.Includes bibliographical references (page 18)by İbrahim Mert Öztürk