Effect of freezing and thawing on strength and permeability of lime-stabilized clays

AbstractIn this study, the effect of freezing and thawing on the strength and permeability of two clayey soils (high and low plasticity), which had been stabilized with lime, were investigated. Before and after stabilization, the permeability and strength of the specimens were determined with various freeze-thaw cycles. Results of this study indicated that for both clays, 6% lime addition increased the hydraulic conductivity of the specimens 1000 times. However, the hydraulic conductivity of clay with 6% lime increased 10–20 times after only 3 freeze-thaw cycles. The results of strength tests exhibited different trends. The strength of stabilized high plasticity clay increased approximately 15 times at the end of 28 day curing, whereas the strength of stabilized low plasticity clay increased about 3 times only. The strength of both stabilized clays decreased 10–15% at the end of the freeze-thaw cycles

Optimal time sharing strategies for parameter estimation and channel switching problems

Ankara : The Department of Electrical and Electronics Engineering and The Graduate School of Engineering and Science of Bilkent Univesity, 2014.Thesis (Ph. D.) -- Bilkent University, 2014.Includes bibliographical references leaves 103-108.Time sharing (randomization) can offer considerable amount of performance improvement in various detection and estimation problems and communication systems. In the first three chapters of this dissertation, time sharing among different signal levels is considered for parametric estimation problems. In the final chapter, time sharing among different channels is investigated for an average power constrained communication system. In the first chapter, the aim is to improve the performance of a single fixed estimator by the optimal stochastic design of signal values corresponding to parameters. It is obtained that the optimal parameter design corresponds to time sharing between at most two different signal values. In the second chapter, the problem in the first chapter is generalized to a scenario where there are multiple parameters and multiple estimators. In this scenario, two different cost functions are considered. The first cost function is the total risk of all the estimators. The optimal solution for this case is time sharing between at most two different signal values. The second cost function is the maximum risk of all the estimators. For this case, it is shown that the optimal parameter design is time sharing among at most three different signal values. In the third chapter, the linear minimum mean squared error (LMMSE) estimator is considered. It is observed that time sharing is not needed for the LMMSE estimator, but still the performance can be improved by modifying the signal level. In the final chapter, the optimal channel switching problem is studied for Gaussian channels, and the optimal channel switching strategy is determined in the presence of average power and average cost constraints. It is shown that the optimal channel switching strategy is to switch among at most three channels.Soğancı, HamzaPh.D

Doppler frequency estimation in pulse doppler radar systems

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2009.Thesis (Master's) -- Bilkent University, 2009.Includes bibliographical references leaves 59-62.Pulse Doppler radar systems are one of the most common types of radar systems, especially in military applications. These radars are mainly designed to estimate two basic parameters of the targets, range and Doppler frequency. A common procedure of estimating those parameters is matched filtering, followed by pulse Doppler processing, and finally one of the several constant false alarm rate (CFAR) algorithms. However, because of the structure of the waveform obtained after pulse Doppler processing, CFAR algorithms cannot always find the Doppler frequency of a target accurately. In this thesis, two different algorithms, maximum selection and successive cancelation, are proposed and their performances are compared with the optimal maximum likelihood (ML) solution. These proposed algorithms both utilize the advantage of knowing the waveform structure of a point target obtained after pulse Doppler processing in the Doppler frequency domain. Maximum selection basically chooses the Doppler frequency cells with the largest amplitudes to be the ones where there is a target. On the other hand, successive cancelation is an iterative algorithm. In each iteration, it finds a target that minimizes a specific cost function, until there are no more targets. The performances of these algorithms are investigated for several different point target scenarios. Moreover, the performances of the algorithms are tested on some realistic target models. Based on all those observations, it is concluded that maximum selection is a good choice for high SNR values when a low-complexity algorithm is needed, on the other hand, successive cancelation performs almost as well as the optimal solution at all SNR values.Soğancı, HamzaM.S

Annelik statüsünün bir güç kaynağı olarak şiddet uygulamaya etkisi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Annelik biyolojik temelinin yanı sıra sosyokültürel boyutu ile gündeme gelen karmaşık anlam ve içeriğe sahip bir olgudur. Anneliğin biyoloji ve deneyim odaklı açıklamaları hangi duygu, düşünce ve davranma biçimlerinin anne olmak ve annelik yapmak olarak değerlendirilebileceğine ilişkin farklı açıklamalar sunmaktadır. Biyoloji temelli açıklamalar kadınların anne olması ve çocuğun bakım ve yetiştirilme pratiklerini üstlenmesinin doğal, içgüdüsel ve evrensel olduğunu savunmaktadır. Deneyim odaklı açıklamalar ise anneliğin tüm sağlıklı ve normal kadınlar tarafından benzer şekilde deneyimlenmediğini aksine karmaşık ve dinamik bir süreçle sosyokültürel bağlamda bireysel olarak inşa edildiğini savunmaktadır. Bu noktadan hareketle çalışmada (i) annelerin annelikle ilgili gördükleri çocuk bakım ve yetiştirme pratikleri, (ii) bu pratikleri deneyimleme düzeyleri ve (iii) annelerin annelik şiddetini meşrulaştırma eğilimleri ele alınmaktadır. Bu amaçla İstanbul İli, Beylikdüzü ilçesinde ikamet eden 383 anne ile araştırmacı tarafından geliştirilmiş ölçek uygulaması yapılarak annelerin annelik algıları, annelik deneyimleri ve annelik şiddetini meşrulaştırma düzeyleri araştırılmıştır. Verilerin analizinde yüzde, frekans ve aritmetik ortalama değerleri ile Kikare Testi, Tek Örneklem Kolmogorov Smirnov Testi, Kruskal Wallis Testi ve Korelasyon Analizi kullanılmıştır. Çalışmanın temel bulguları; annelerin çocuk bakım ve yetiştirme pratiklerini annelik görevleri olarak değerlendirdiği, annelerin annelik algıları ile annelik deneyimleri arasında anlamlı ve pozitif yönlü ilişkinin olduğu ve annelerin çocuk bakım ve yetiştirme sürecinde çocukların olumlu kabul edilen davranışlara yönlendirilmesi olumsuz kabul edilen davranışlardan uzaklaştırılması için annelik şiddetini meşru bir uygulama olarak değerlendiği şeklindedir.Motherhood is a phenomenon with a complex meaning and content that has a sociocultural dimension along with a biological basis. Explanations on motherhood that depend on biology or experience give different accounts on the question which types of feeling, thinking and acting may be considered as being a mother or acting like one. Biological explanations regard women's becoming a mother and taking the responsibility of a child's care and growth as natural, instinctive and universal. Explanations based on experience, on the other hand, reject the idea that motherhood is always experienced as the same by every healthy and normal woman, and claim that it is constructed individually with a dynamic process in a sociocultural context. Taking these into account, this study examines (i) the child care and nurturing practices that mothers see relevant with motherhood, (ii) the levels they experience these practices and (iii) their tendency to rationalize or legitimize the mother's violence against her child. To this end, mothers' motherhood perception, motherhood experiences and their level of legitimizing mother's violence are measured via a scale developed by the researcher herself with 383 mothers from Beylikdüzü district of İstanbul. Percentage, frequency, arithmetic mean, Chi-square Test, One Sample Kolmogorov Smirnov Test, Kruskal Wallis Test and Correlation Analysis are used during the process of evaluating the data. The basic findings of the study are as such: Mothers see the child's care and nurturing as a motherhood responsibility. There is a positive correlation between their perception and experience of motherhood. They regard mother's violence in the process of his/her growth as legitimate in order to lead the child to praised deeds and avoid him/her from the condemned ones

Localized plasmon-coupled semiconductor nanocrystal emitters for innovative device applications

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2007.Thesis (Master's) -- Bilkent University, 2007.Includes bibliographical references leaves 74-83Quantum confinement allows for the development of novel luminescent materials such as colloidal semiconductor quantum dots for a variety of photonic applications spanning from biomedical labeling to white light generation. However, such device applications require efficient photoluminescence. To this end, in this thesis we investigate the spontaneous emission characteristics of semiconductor nanocrystal emitters under different conditions and their enhancement and controlled modification via plasmonic resonance coupling, placing metallic nanoparticles in their proximity, for innovative device applications. We first present our theoretical and experimental work on the optical characterization of nanocyrstals (e.g., CdSe, CdS, and CdSe/ZnS) including absorption/photoluminescence, time-resolved luminescence, and excitation spectra measurements. Here we demonstrate very strong electromodulation (up to 90%) of photoluminescence and absorption of such nanocrystals (nanodots and nanorods) for optical modulator applications. Second, we present our electromagnetic modeling on the optical response of metal nanoparticles using finite-difference-time-domain method. For the first time, using localized plasmons of metal nanoisland films (nano-silver) carefully spectrally and spatially tuned for optimal coupling conditions, we report very significant controlled modifications of nanocrystal emission including the peak emission wavelength shift (by 14nm), emission linewidth reduction (by 10nm with 22% FWHM reduction), photoluminescence intensity enhancement (15.1- and 21.6-fold compared to the control groups of the same nanocrystals with no plasmonic coupling and those with identical nano-silver but no dielectric spacer in the case of non-radiative energy transfer, respectively), and selectable peaking of surface-state emission at desired wavelengths. Such localized plasmonic engineering of nanocrystal emitters opens new possibilities for our lightemitting and photovoltaic devices.Soğancı, İbrahim MuratM.S

PARENTS’ PARTICIPATION IN DISTANCE SPECIAL EDUCATION PRACTICES: A REVIEW ON TEACHERS’ OPINIONS

In this study, the opinions of teachers on the participation of parents who had children with special needs in their children’s education processes during the pandemic were examined with a phenomenological design, which is one of the qualitative study methods.  The study group consisted of 22 special education teachers. The data of the study were collected with a semi-structured interview form that was developed by the researchers, expert opinion was taken and finalized in line with the corrections. In the present study, in which the participation of parents who had children with special needs in the education process of their children in the Covid 19 pandemic was examined from the perspective of teachers, the teachers expressed their opinions about the practices they made to ensure parental participation in the distance education process, the motivations of the parents to participate, the difficulties they faced in ensuring parental participation, the effects of parental participation. When the findings of the study were examined, the teachers guided the family by explaining the materials used to ensure parental participation in the distance education process, providing information on the necessary issues, following the homework assignments and home practices and giving feedback, and evaluating the process. Teachers also ensured the continuity of communication in the family and teacher channel through online applications to facilitate and increase the participation of parents. They encouraged the use of EBA and created complementary activities, ensuring that especially daily life skills continued to be practiced in the home setting with parents’ support

Yeşil kimya ile iletken polimer sentezi ve elektrokromik özellikleri

Thanks to their interesting optical and electrical properties, conductive polymers are one of the materials to have highest potential utility in technological applications. But theirs usage in practical applications are limited due to poor solubility, cannot be easily processed and lack of good mechanical strength and stability. In this work synthesis of conductive polymer was achieved in environmentally friendly aqueous dispersion of polystyrene sulfonic acid instead of harmful organic solvent (dichloromethane, acetonitrile, chloroform,). Thus, a water-insoluble monomer was polymerized in an aqueous medium instead of organic solvents which are harmful to environment and human health. Also, conductive polymer obtained in aqueous medium has superior optical and electrical properties than the conductive polymer obtained in the presence of organic solvents. This paper has been shown that other conductive polymers synthesized in hazardous organic solvents can be synthesized in aqueous media with superior optic and electrical properties which is important for the technological application

Amalgam Yüzeyine Uygulanan Farklı Yüzey İşlemlerinin ve Farklı Adeziv Sistemlerinin Ortodontik Amaçlı Molar Tüplerin Bağlanma Dayanımları Üzerine Etkilerinin Değerlendirilmesi

Amaç: Bu araştırmanın amacı,  kumlama, elmas frez ve Er-YAG lazer ile pürüzlendirilmiş farklı amalgam yüzeylerine farklı yapıştırma sistemleri ile yapıştırılmış ortodontik molar tüplerin bağlanma dayanımlarının belirlenmesidir.Gereç ve Yöntemler: Kendiliğinden sertleşen akrilik ile imal edilen 60 kalıpta molar tüpler için standart boşluklar hazırlanıp, amalgam ile doldurulmuştur. Numuneler rastgele yüzey pürüzlendirmesi için 20 parçadan oluşan 3 gruba ayrılmış ve ayrıca 2 farklı yapıştırıcıya göre 2 alt gruba bölünmüştür. 1. grupta yüzeyler elmas frezle, 2. grupta aliminyum oksit tozu ile 3. grupta ise Er-YAG lazer ünitesi ile pürüzlendirilmiştir. Molar tüplerinin bütün gruplardaki amalgam yüzeylerine bağlanması için 2 farklı yapıştırma sistemi uygulanmıştır. Universal test makinesi kullanılarak makaslama kuvveti ile söküm gerçekleştirildi. Bulgular: Ortodontik molar tüplerin, amalgam yüzeylerine bağlanma dayanımı değerlerinde farklı pürüzlendirme yöntemlerine ve 2 farklı yapıştırma sistemine göre istatistiksel olarak anlamlı fark bulunmadı. Sonuçlar: Amalgam yüzeyindeki tüm yüzey pürüzlendirme işlemlerinin, bu çalışmada kullanılan 2 farklı yapıştırma sistemi ile yapıştırılan ortodontik molar tüplerin, tüm gruplarda benzer bağlanma dayanımına sahip olduğu saptanmıştır.Anahtar Kelimeler: Adheziv sistemler, Amalgam, Ortodonti, Er-YAG lazer, Bağlanma dayanım

Broyler rasyonlarında kitooligosakkarit (KOS) kullanımının performans, karkas verimi, iç organ ağırlıkları ve bazı kan parametreleri üzerine etkileri

Tez (Doktora) -- Kırıkkale Üniversitesi119524