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Yayın Cooperative strategies, achievable rates and resource allocation for OFDMA channels(Işık Üniversitesi, 2011-07-28) Bakım, İsmail Sezi; Kaya, Onur; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Doktora ProgramıThe design of next generation wireless communication systems brings along new challenges, since the degrading factors such as fading and multi-user interference become harder to deal with as the number of users and the bandwidth require- ments increase. Orthogonal Frequency Division Multiple Access (OFDMA) is a multiple accessing technique which provides a solution to both of the problems above: it provides a relatively simple way of assigning available bandwidth to users, while avoiding interference; and at the same time, it converts a frequency selective fading channel, to parallel flat fading subchannels, hence reducing the effects of intersymbol interference. However, in wireless channels, what is tradi- tionally considered as interference is in fact side information, and combined with the diversity created by the orthogonal subchannels in OFDMA, this side infor»mation can be carefully taken advantage of to increase the rates achievable by the users. In our thesis, without imposing any prior constraints on subchannel allocation, we investigate cooperation strategies, achievable rates and resource allocation for OFDMA channels. We propose new cooperative encoding strategies for wireless communication net- works över OFDMA channels. We particularly focus on a two user cooperative OFDMA system, based on block Markov superposition encoding (BMSE). We obtain expressions of the resulting achievable rate regions for ali proposed coroperative encoding strategies. We show that, by allowing for re-partitioning and re-encoding of the cooperative messages across subchannels, it is possible to better exploit the diversity created by OFDMA, and higher rates can be achieved. In order to take full advantage of the diversity created by OFDMA, we then introduce a channel adaptive cooperation strategy for OFDMA, and optimize the transmit powers as a function of the channel states. We provide the optimality conditions that need to be satisfied by the powers associated with the users' codewords and derive the closed form expressions for the optimal powers.Yayın Yeraltı sanatının kurumsallaşması(Işık Üniversitesi, 2022-06-13) Ergen, İpek; Kara Sarıoğlu, Didem; Işık Üniversitesi, Lisansüstü Eğitim Enstitüsü, Sanat Bilimi Doktora ProgramıYeraltı kültürünün kimi iletişim ve ifade biçimleri; kısıtlı bir gruba yönelik ve çoğu zaman yasa dışı ilerleyen uygulamalardan, geniş bir izleyici kitlesine sahip, kabul edilmiş sanatsal pratiklere evrilmişlerdir. Galeri ve müze gibi kurumlar bir zamanlar dışlanan ve hatta suç unsuru olarak kabul edilen bu sanat türlerine programlarında yer vermeye başlamıştır. Böylelikle yeraltı sanatı terimi altında toplanan bu alternatif sanat pratiklerinin kurumsallaşma ile artan görünürlüğü, ardından akademik kabul, popülerleşme ve ticarileşme gibi adımları getirmiştir. Yeraltı sanatının kurumsallaşma aşamaları bu tezde ilk olarak graffiti ve sokak sanatı hareketlerinin sanat galerilerine geçiş süreci açısından ele alınmıştır. Günümüzde sokak sanatı kavramının bir çağdaş sanat akımı, pek çok yapıtın adı altında incelendiği bir tür olarak literatüre geçmesi sonucunda bu kavram dönüşüm geçirmiş ve sokak sanatı atölye ortamında üretilen, galerilerde, müzelerde, müzayedelerde sergilenen çalışmaları da kapsayacak şekilde genişlemiştir. Bu durum, yeraltı sanatının yaşadığı kurumsallaşma ardından gelen dönüşümü ortaya koyan en net örnek olarak paylaşılmıştır. Ardından Amerikan yeraltı kültürünün, sokak sanatı, çizgi roman gibi ifade biçimlerinden ilhamla hareket eden lowbrow sanat akımı üzerinden kurumsallaşma aşamaları ele alınmış; yaşanan dönüşüm bu hareketin temsilcisi olan galerilerin zaman içerisinde yaşadıkları gelişim şeması üzerinden irdelenmiştir. Son olarak Japonya'da iletişim, ifade ve hareketlerini kapalı gruplar ve daha önceki yeraltı kültürü örneklerinde görülen yöntemler üzerinden ilerleten bir altkültür olan otaku kültürü ve bu kültüre ait öğelerin yüksek sanat, popüler kültür ve tasarım ile buluşmasını sağlayan superflat akımı örnekleri incelenmiştir. Örnekler üzerinden kurumsallaşmanın aşamaları araştırılırken, bağlamından koparılan yapıtın bu süreç ve sonrasında yaşadığı dönüşümün yapıtın kendisi, çevresi ve izlerkitlesi açısından ortaya koyulması amaçlanmıştır.Yayın An inverse source problem connected thermoacoustic imaging in multi-layer planar medium(Işık Üniversitesi, 2018-06-04) Yücel, Hazel; Uzun, Banu; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Matematik Doktora ProgramıIn this thesis, we mentioned imaging technics used today, and microwave induced thermoacoustic procedure and imaging. We made literature survey about solution of the thermoacoustic equation for homogeneous and inhomogeneous medium. We modelled the inhomogenity of medium as a multi-layer planar structure and de?ned initial condition, continuity conditions on the layer boundaries and radiation conditions at in?nity, then we derived analytical forward and inverse solution of the thermoacoustic wave equation for inhomogeneous medium with the source distribution existing in all layers. Our solution of inverse source problem is based on the methods of the Green’s functions for layered planar media. For qualitative testing and comparison of the point-spread functions associated with the conventional solution for homogeneous medium and our derived layered solutions, we performed numerical simulations. In numerical simulations ?rst we generated the measured data by using the derived forward solution for multi-layer planar medium and then we used conventional inverse solution and our derived inverse solution to image source distribution. Our simulation results showed that the conventional inverse solution based on homogeneous medium assumption, as expected, produced incorrect locations of point sources, whereas our inverse solution involving the multi-layer planar medium produced point sources at the correct source locations. Also, we showed that the performance of layered inverse solution is sensitive to the validity of the layer parameters and medium parameters used as prior information in the measured data. Our inverse solutions based on multi-layer planar media are applicable for cross-sectional 2 dimensional imaging of the organs such as breast, skin, and abdominal structure.Yayın Factors encouraging and hindering a wider acceptance and more frequent utilization of mobile payment systems an empirical study among mobile phone subscribers in Turkey(Işık Üniversitesi, 2021-06-21) Coşkun, Ertan; Ferman, Murat; Işık Üniversitesi, Sosyal Bilimler Enstitüsü, Çağdaş İşletme Yönetimi Doktora ProgramıConsidering the technological development in mobile payment technology, and extensive literature of technology adoption models; the current state of the related field needs to be examined in more detail to better understand current situation. Such an investigation may be invaluable to enable further expansion, consumer acceptance, market adoption, and help to improve the existing platforms’ usability. This research deals with determining the factors that affect adoption of mobile payment technology among consumers, in Turkey. It seeks to find any patterns and connections that may be of aid in framing an implementation strategy for facilitating further adoption. It has gathered different definitions of “mobile payment” in literatüre and used a consumer side definition. This study offers a different perspective by grouping constructs from a broader literature and provides a mobile payment acceptance model based on the constructs used in other studies. Previous studies have been performed with small groups of respondents. This study aims to perform the research model in a cosmopolitan city (Istanbul) where all sorts of mobile payment options are available in the market and in the time of a pandemic when remote delivery and online purchases are widely preferred compared to offline alternatives. A survey is conducted among mobile phone subscribers in Istanbul, Turkey for primary data collection phase of this research. Istanbul is the city that holds the biggest population and has the highest amount of mobile phone subscribers in the country. Istanbul’s current population is more than 15.6million and mobile phone subscriptions are more than 22million as of 2019. Survey responses have been analysed with structural equation modeling and results are presented in the corresponding sections. Empirical findings of the research show that factors such as usefulness, security, social influence, ease of use, enjoyment and innovativeness have positive effects on use of mobile payments among consumers. Factors such as attractiveness of alternatives and new technology anxiety have negative effects on use of mobile payments. This study has also discovered that intention to use mobile payments differ among demographic parameters such as education level and gender of respondents.Yayın Metamutator: Its Realizations and Its Applications(Işık Üniversitesi, 2019-07-22) Minayi, Elham; Göknar, İzzet Cem; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Doktora ProgramıMutators became very popular after 1971, when Leon Chua realized the memristor, his postulated fourth circuit element, using them. The reason for the popularity of mutators, which are easily realizable 2-port devices, lies in the fact that they render possible the simulation/emulation of, hence experimentation with, postulated non-existing (not o the shelf available) elements like memstors.1 On the other hand, in the literature when simulating/emulating elements with 2- ports, many 4-port \generalized mutator-like" realizations that nobody has been able to identify are being used. These underlying 4-ports, and their ability to act as a mutator when two of the ports are properly terminated, have been thus named metamutator. In this thesis, in addition to introducing some of metamutator realizations, newly designed metamutator circuits with one or two active devices are introduced. Also, a new active device, with only twelve transistors, named Additive and Differential IC (AD-IC), is proposed with its layout and use in metamutator circuit design. In addition, many 1-port and 2-port circuit realizations using metamutators have been introduced. 1-port applications are memstor simulation/emulation, oating and/or grounded impedance scaling which comprise inductance simulation, capacitance multiplication, oscillators and Frequency Dependent Negative Resistor (FDNR) simulation. 2- port applications cover Voltage Mode Multiple Input Single Output (VM-MISO) and Current Mode Single Input Multiple Output (CM-SIMO) universal lters and implementations of transconductance and transimpedance ampli ers. Also, two di erent applications of AD-IC: ADIC based analog multiplier and AD-IC based full-wave recti er are proposed in the thesis.Yayın Factors affecting understanding and applications of branded housing project marketing around the İstanbul metropolitan area(Işık Üniversitesi, 2015-01-28) Polat, Selçuk; Ferman, Ali Murat; Işık Üniversitesi, Sosyal Bilimler Enstitüsü, Çağdaş İşletme Yönetimi Doktora ProgramıMarketing is a very important issue to corporate success in today’s competitive business environment. Company’s growth and success can be strongly influenced by marketing practices. Developing marketing strategies can provide significant advantages for companies over their competitors. The aim of this study is to investigate the critical factors affecting understanding and applications of ‘branded housing project marketing’ around the Istanbul metropolitan area. Branding and market positioning depend on fulfillment of certain conditions and key criterion.It is known that the following criterion- structure of companies, quality of the product, professional services, marketing and communications perspectives- both constitute important process and leverage to increase the perceived value of a product or a company in the market. It is crucial for companies to build a solid brand in today's highly-competitive markets to benefit from the brand-related advantages such as, creating overall differentiation providing costumer encouragement and maintaining overall image of high quality. Nowadays, construction companies which build branded housing projects have already established themselves as prime actors of one of the leading and most dynamic sectors of the Turkish economy.It is an observed fact that the brand- related activities are becoming of a more strategic parameter in construction industry. In relation to this fact, each and every housing project aim to be related with a unique identity and brand image. Especially in residential real estate sector, due to the high economic values involved, marketing and sales activities are classified as crucial elements of corporate conduct.Yayın An exploratory research among fashion business leaders and neuromarketing company executives on the perception of applied neuromarketing(Işık Üniversitesi, 2020-01-20) Kurtoğlu, Ali Levent; Ferman, Ali Murat; Işık Üniversitesi, Sosyal Bilimler Enstitüsü, Çağdaş İşletme Yönetimi Doktora ProgramıSince almost two decades conditions that influence consumer purchase behaviour keep on changing in a dynamic manner which result in faster, better, more accurate and more precise managerial decisions’ necessity that are based on deep marketing insights. Although Kotler’s 4Ps and related policies do bare still the same importance to contribute to these marketing insights; How academicians interpret these according to varying conditions of the market structure and human needs, how companies acquire this data , how they apply it to their final solution to make the edge and deliver the superior value, how fast and how much resource they allocate to it, are thoroughly altered by the birth of neuromarketing methods. Having stepped further from baby steps to a more mature but still evolving marketing platform, neuromarketing methods such as fMRI, EEG, Eye Tracking, Virtual reality, Facial Coding and Biometrics make it possible to fill in the gap between how to reach needed consumer intrinsic perceptions and a product’s or service’s quality and/or price evaluation by the consumers amongst other marketing mix elements. This dissertation aims to be an exploratory study and targets to evaluate the perception and attitude among high ranking executive leaders in Turkish Fashion Industry towards applied neuromarketing along with how neuromarketing companies in Turkey that apply these methods and deduct meaningful strategic marketing and management pathways while interpreting the intersection and expose findings about current status along with possible future business solutions for both sides by using in-depth interviews. This dissertation aims to be an exploratory study and targets to evaluate the perception and attitude among high ranking executive leaders in Turkish Fashion Industry towards applied neuromarketing along with how neuromarketing companies in Turkey that apply these methods and deduct meaningful strategic marketing and management pathways while interpreting the intersection and expose findings about current status along with possible future business solutions for both sides by using in-depth interviews. There are three different phases of how the research was conducted. The initial phase includes a comprehensive review of current knowledge on academical databases about theoretical and applied neuromarketing globally as well as locally which aims to shed light on the definition, borders and usability of neuromarketing. The second stage covers in-depth interviews with fashion business leaders and neuromarketing company executives in Turkey which investigates how well neuromarketing is known, applied and what kind of future potentials as well as possible threads it may create for both sides Primary and secondary data are used in those stages to set the correct data. Final stage of the dissertation is about cross-matching the first-hand data with the neuromarketing review with a qualitative analysis and intends to summarize the current status on the perception of neuromarketing on business and the perspective of applicability of it in short- and long-term future.Yayın Travmatik yaşantıların obsesif kompulsif bozukluk ve dikkat eksikliği hiperaktive bozukluğu ile ilişkinde aracı ve düzenleyici değişkenlerin etkisinin incelenmesi(Işık Üniversitesi, 2023-10-02) Uzunoğlu Azman, Gülgün; Aktan, Zekeriya Deniz; Işık Üniversitesi, Lisansüstü Eğitim Enstitüsü, Klinik Psikoloji Doktora ProgramıTravmatik deneyimler insanların hayatlarında birçok olumsuzluklara neden olabilmekte ve etkisini farklı alanlarda, farklı belirtiler ile gösterebilmektedir. Bununla birlikte, Obsesif Kompülsif Bozukluk (OKB) ve Dikkat Eksikliği Hiperaktivite Bozukluğu (DEHB) gibi psikopatolojik belirtiler biyolojik kökenli olabildiği gibi, travmatik yaşantıların etkisiyle dışsallaştırma bozukluğu olarak da açığa çıkabilmekte ve travmatik deneyimler sonrası gözlenen belirtiler ile benzer özellikte olabilmektedir. Ayrıca, ergenlerin içinde bulunduğu gelişim döneminin özelliklerinin de etkisi ile, bu psikopatolojik belirtiler gelişim dönemine has olarak değerlendirilerek, bireylere yanlış bir bakış açısı sunabilmektedir. Bu doğrultuda, araştırmanın amacı 12-18 yaş arası ergenlerin OKB ile DEHB belirtilerinin varlığında travma ile ilişki ruhsal, duygusal ve bilişsel bileşenlerin önemini ortaya koymak ve DEHB ve OKB ile travma ilişkisinde, travma sebepli koruyucu, biçimlendirici, aracı olan ve risk oluşturan etmenleri değerlendirebilmek olarak belirlenmiştir. 794 katılımcı ile yürütülen araştırmada, Sosyodemografik Özellikler ve Veri Formu, DSM-5 Travma Sonrası Stres Belirtileri Şiddet Ölçeği Çocuk Formu, Obsesif Kompülsif Bozukluk Ölçeği Çocuk Formu, Turgay Yıkıcı Davranış Bozuklukları Belirti Tarama Ölçeği, Ergenler için Benlik Algısı Ölçeği, Çocuk ve Ergenler için Sosyal Destek Değerlendirme Ölçeği, Bilişsel Esneklik Ölçeği, Ergenler için Duygu Düzenleme Ölçeği ve Ergenler için Duygu Düzenleme Ölçeği kullanılmıştır. Birçok farklı analiz ile verilerin incelenmesi tamamlanmıştır. Araştırma bulgularına göre, travma ile OKB ve DEHB ilişkisinde benlik algısı, sosyal destek, bilişsel esneklik ve içsel işlevsel olmayan ile dışsal işlevsel olmayan duygu düzenlemenin aracı rolünün istatistiksel olarak anlamlı bir etkisi olduğu; travmanın türünün, sayısının ve üzerinden geçen sürenin ise ayrı ayrı biçimlendirici rolünün istatistiksel olarak anlamlı olmadığı bulunmuştur. Aracı ve biçimlendirici etkinin bir arada incelendiği araştırma modellerinin değerlendirmesinde ise sadece travmanın üzerinden geçen sürenin biçimlendirici değişken; benlik algısı, sosyal destek, bilişsel esneklik ve duygu düzenlemenin aracı değişken; travma belirti düzeyinin yordayıcı değişken ve DEHB belirti düzeyinin ise yordanan değişken olarak belirlendiği araştırma modelinin anlamlı bir etkileşim gösterdiği bulunmuştur. Araştırmanın katkısı, tüm bunlar ışığında, OKB’li ve DEHB’li ergenlerin tedavisinde travmatik yaşam olaylarının ve travma belirti düzeyinin başlı başına psikopatolojiler üzerinde belirleyici olabildiğinin ve bu ilişkilerde aracı ve biçimlendirici ruh sağlığı değişkenlerinin de göz önünde bulundurulması gerekmesinin öneminin anlaşılmasıdır.Yayın Boutique pastry management as a rising services marketing practice and a comprehensive survey of boutique pastries in İstanbul(Işık Üniversitesi, 2008) Demir, Gülper; Ferman, Ali Murat; Işık Üniversitesi, Sosyal Bilimler Enstitüsü, Çağdaş İşletme Yönetimi Doktora ProgramıConsumption of food and beverages always holds a place at the top of the list when we analyze the daily habits of consumption of human beings. The different behaviors of consumers towards food and beverage products force the relevant producers to define their consumer profiles and most appropriate marketing strategies in accordance with their target group . In food industry, customization of products can also be observed in addition to the traditional massive production strategies. Therefore, the number of enterprices like boutique pastries which produce customized products that both possess an artistic value and aims complete contentment of their customers as well is increasing very rapidly day by day in Istanbul. Although boutique pastries exist in service sector, they are forced to develop marketing strategies that are specific to their need due to the several reaons such as market demands and infinite diversity of the product opportunities, which carry artistic value. With this research , certain phenomena are explored: boutique business making customization of production and adding artistic value to the products. While conducting interviews with managers of boutique pastries provided us with information about the current state of the business, the surveys enabled us to learn more about the current state of the business, the surveys enabled us to learn more about purchase behaviours. As a result of this research, the most appropriate marketing methodologies for boutique pastry businesses are defined in accordance with the analyses consumer behaviours.Yayın Ring array processing for forward-looking intravascular and intracardiac ultrasonic imaging(Işık Üniversitesi, 2010-06-08) Tekeş, Coşkun; Karaman, Mustafa; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Doktora ProgramıForward-looking (FL) catheter-based imaging systems are highly desirable for guiding interventions in IVUS and ICE applications. One of the main challenges in the array based FLIVUS systems is the large channel count which results in increased system complexity. Synthetic phased array processing with reduced firing count simplifies the front-end and hence can enable 3-D real-time imaging. Recently, we have investigated dual-ring arrays suitable for IVUS and ICE imaging. In this dissertation, we present and explored two different optimized array designs based on dual circular and hexagonal rings that are suitable for synthetic phased array processing with reduced number of firings. We used simulated annealing to optimize the wideband PSF of the array system. The optimal firing set from different Tx-Rx elements eliminates most of the redundant spatial frequencies in the coarray and produces low side lobes and number of firings. The optimization procedure starts with the calculated wideband PSF of the full set coarray including all Tx-Rx firing combinations. In every iteration step, a predefined coarray with only one element change is compared with the previous set in terms of cost function. For the two designs, we obtained optimal reduced set by minimizing both the peak side lobe level and the integrated side lobe energy. For two test cases, we obtained reduced sets of 512 and 256 coarray elements, and constructed 2-D PSFs. The simulation results show that the optimized dual circular and hexagonal ring arrays provide up to 10-dB and 5-dB improvements, respectively, in peak near side lobe level with no widening in main lobe width. Our test results show that the side lobe levels of the dual circular and hexagonal arrays can be remarkably and controllably reduced by using simulated annealing optimization, and the resulting optimal array designs can meet the resolution and speed requirements of 3-D real time IVUS and ICE imaging.
