Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Research Project Yenilenebilir Enerji İçin Ödeme İstekliliği Ve Bu İstekliliği Etkileyen Faktörlerin Analiz Edilmesi(TUBİTAK, 2018) Doğan, EyüpBu projede, Türkiye?de ikamet eden hanehalkının yenilenebilir enerji için ödeme istekliliği (YÖİS) ve bu istekliliği etkileyen faktörler analiz edilecektir. İlgili literatür kapsamında, gelişmiş ve gelişmekte olan birçok ülke için YÖİS ve bu istekliliğe etki eden faktörler incelenmesine rağmen, daha önce bu alanda Türkiye üzerine bir çalışma yapılmamıştır. Bu projenin amacı, Türkiye?deki vatandaşların YÖİS ve bu istekliliği etkileyen değişkenleri inceleyerek literatürdeki bu boşluğu doldurmaktır. Ayrıca, Sundt ve Rehdanz (2015) ?ın meta-analiz çalışması, ilgili literatürdeki çoğu makalenin yaş, eğitim seviyesi, gelir düzeyi ve çevresel duyarlılık gibi faktörlerin olası etkisini analiz etmesine rağmen sadece bir kaç makalenin hanehalkı sayısını ekonometrik modele dahil ettiğini göstermiştir. Bu proje, coğunlukla kullanılan demografik faktörlerin yanısıra hanehalkı sayısınında YÖİS?i etkileyip etkilemediğini araştıracaktır. Bu projeyi gerçekleştirebilmek için koşullu değer yöntemiyle hazırlanan toplam 2 bölüm ve 26 sorudan oluşan bir anket kullanılacaktır. Yüzyüze görüşme yöntemiyle Türkiye?nin 12 farklı İBBS bölgesinden toplam 2,500 kişiyle yüzyüze görüşme yöntemiyle doldurulacak anketlerden elde edilecek bilgiler sayesinde, Türkiye?de ikamet eden hanehalkının ortalama YÖİS miktarı ve hangi faktörlerin bu istekliliği anlamlı yada anlamsız etkilediği çeşitli yöntemler kullanılarak analiz edilecektir. Türkiye, Avrupa Birliğine aday bir ülke, G-20 ekonomilerinden birisi ve NATO?ya dahil bir ülke olmasının yanısıra, Dünya ve Avrupa enerji piyasasında da önemli bir konuma sahiptir. Ayrıca, yenilenebilir enerji alanında kısa ve orta vadede yapılması hedeflenen yatırımlarda göz önüne alındığında, Türkiye bu literatür içerisinde araştırılması gereken ülkelerin arasındadır. Bununla birlikte, son zamanlarda küresel ısınma, gaz emisyonu ve çevresel kirlilik gibi faktörler global bir sorun haline gelmiştir. Yenilenebilir enerjinin kullanımı daha temiz bir çevre için önemli bir unsurdur. Türkiye enerjide dışa bağımlı bir ülkedir. Ayrıca, Türkiye'nin elektrik enerjisinin %48'inin doğal gazdan üretiliyor olmasının yarattığı kırılganlığın son dönem Rusya krizi ile görülmüş olması sonrasında enerji karmasında çeşitlendirme çok daha hassasiyet kazanmıştır. Yenilenebilir enerjinin artırılması bağımlılığı azaltacak önemli bir araçtır. Hanehalklarının katılımı, hedeflenen yenilenebilir enerji projelerinin hayata geçirilmesini kolaylaştıracaktır. Bu proje dört ana hedefe ulaşmak üzerine odaklanmıştır: i) Türkiye?de ikamet eden hanehalklarının yenilenebilir kaynalardan üretilen elektrik enerjisi almak için ödemeye razı oldukları ortalama miktarı bulmak, ii) YÖİS?i etkileyebilecek yaş, cinsiyet, gelir düzeyi, egitim seviyesi, çevreye olan duyarlılık ve hanehalkı sayısı gibi faktörleri analiz etmek, iii) yenilenebilir enerji yatırımlarının hanehalkları tarafından desteklenmesine olanak sağlayacak bir politikanın Türkiye?de uygulanabilirliğini ortaya koymak, iv) bu proje çıktılarını uluslararası indekslerce taranan bir dergide yayınlatmak.Master Thesis PERFORMANCE EVALUATIONS OF SINGLE MODE OPTICAL RECEIVER FOR DEGRADED VISUAL FIELD AND PHOTONIC LANTERN BASED COHERENT DETECTION(Abdullah Gül Üniversitesi, 2016) ORAN, ABDULLAHImaging at degraded visual environments is one of the biggest challenges in today’s imaging technologies. Especially military and commercial rotary wing aviation is suffering from impaired visual field in sandy, dusty, marine and snowy environments. For example, during landing the rotor churns up the particles and creates dense clouds of highly scattering medium, which limits the vision of the pilot and may result in an uncontrolled landing. The vision in such environments is limited because of the high ratio of scattered photons over the ballistic photons that have the image information. In this thesis, we propose to use optical spatial filtering (OSF) method in order to eliminate the scattered photons and mainly collect the ballistic photons at the receiver. OSF is widely used in microscopy; to the best of our knowledge this thesis will be the first application of OSF for macroscopic imaging. Our experimental results show that most of the scattered photons are eliminated using the spatial filtering in a highly scattering degraded visual field. The results are compared with a standard broad area photo detector which shows the effectiveness of spatial filtering. Free space optical systems have applications in different areas such as laser ranging, three-dimensional imaging, weather predictions and optical wireless communication. Some applications require very high performance free space optical systems that are not available today. The need of systems with higher performance and lower size, weight and power (SWaP) is the biggest research motivation of free space optical systems. Between various detection techniques, vi coherent optical detection comes forward for applications that require high sensitivity and bandwidth. Coherent detection based LIDAR systems have the potential to provide quantum noise limited performance. However coherent systems suffer from poor free space to fiber collection efficiency due to the single mode detection characteristics and small size of the optical fiber. In order to overcome this problem, photonic lantern is introduced to effectively collect the multimode beam coming from free space and convert it to a number of single mode fibers. The photonic lantern consists of a multimode fiber to a number of single-mode fibers. The collection efficiency enhancement of photonic lanterns have been investigated, however there is no study on the signal to noise ratio –performance- improvement on the photonic lantern based free space coherent systems. In this thesis; the effect of random distribution of the optical power in the 19-port photonic lantern will be investigated mathematically. The photonic lantern based coherent detection system performance will also be simulated by using the MATLAB software. The output of this thesis may open the path to experimental demonstration and maybe even to a prototype.Master Thesis Phase noise filtering effects of mode-locked lasers(Abdullah Gül Üniversitesi, 2018) MBONDE, HAMIDUThe subject of Mode-Locked Lasers has experienced a massive growth over the last two decades. Previously meant as the source of ultra-short optical pulses, its concepts have recently expanded to be applicable in areas beyond Optics such as Biomedical[1], Micro-machining[2], Sensing[3] and RF/Microwaves communication[4]. In particular this thesis focuses on application of Mode-Locked Lasers in RF/Microwave communications. One of the common problems with RF communication systems is signal integrity. Due to the nature of oscillation systems that are used to produce RF signals there is always an inevitable amount of undesirable signal associated with main signal being generated. These spurious (noise) signals have significant effect on the efficient performance of particular RF system. Low noisy RF signals are highly desirable and have many applications in high speed communication, RADAR and electronic warfare. Therefore it is critical to have an efficient means of producing low noise RF signals. Generating RF signals by Optical means has emerged as a major solution to this problem. Various methods for optically generating lower noise RF signals of high frequency have been developed such as frequency stabilized mode-locked lasers[5], phase locked loop based oscillators[6] and optoelectronic oscillators[7]. In this thesis a novel approach to this problem is presented, instead of generating lower noise signals a unique method of efficiently filtering the noise of RF signal using Mode-Locked Laser is explained. The first two chapters give brief introduction to mode-locked lasers and phase noise in oscillator, the concepts which will be used throughout this thesis. Then the experimental setups of the proposed system with the results obtained are presented in Chapter 3. Furthermore, theoretical study and analysis of limitations of this method is presented in ii Chapter 4. This includes analysis of these limitations as well as supporting simulations results. Phase noise is frequency domain term which in time domain is referred to as jitters. For various applications it is necessary to determine total jitters value of the system in order to estimate its bit error rates and other performance features. Chapter 5 of this thesis is dedicated to introducing jitter concept and a numerical method of converting a phase noise spectrum into jitter Probability Density Function (PDF).Together with the MATLAB code for aforementioned simulation a special GUI (Graphical User Interface) has been developed for the purpose of converting any given phase noise spectrum into its corresponding jitter PDF. The last chapter gives some concluding remarks and look at the possible futures of this work.Doctoral Thesis FUNCTIONALIZED LOW LUMO [1]BENZOTHIENO[3,2-B][1]BENZOTHIOPHENE (BTBT)-BASED MOLECULAR SEMICONDUCTORS FOR ORGANIC FIELD EFFECT TRANSISTORS(Abdullah Gül Üniversitesi, Fen Bilimleri Enstitüsü, 2021) Özdemir, Resul; Usta, HakanDAcTTs have provided an excellent π-framework for the development of high mobility p-type molecular semiconductors in the past decade. However, n-type DAcTTs are rare and their electron transporting characteristics remain largely unexplored. In the second chapter of this thesis, the first example of an n-type BTBT-based semiconductor, D(PhFCO)-BTBT, has been realized via a two-step transition metal-free process without using chromatographic purification. The corresponding TC/BG-OFET devices demonstrated μe (max) = ~0.6 cm2/Vs and Ion/Ioff ratio = 107-108. The large band-gap BTBT π-core is a promising candidate for high mobility n-type organic semiconductors and, combination of very large intrinsic charge transport capabilities and optical transparency, may open a new perspective for next-generation (opto)electronics. In the third chapter of this thesis, a series of BTBT-based small molecules, D(C7CO)-BTBT, C7CO-BTBT-CC(CN)2C7, and D(C7CC(CN)2)-BTBT, have been developed in “S-F-BTBT-F-S (F/S: functional group/substituent)” molecular architecture. Combining with D(PhFCO)-BTBT, a molecular library with systematically varied chemical structures has been studied herein for the first time for low LUMO DAcTTs, and key relationships have been elucidated. The molecular engineering perspectives presented in this thesis may give unique insights into the design of novel electron transporting thienoacenes for unconventional optoelectronics.Master Thesis Centella asiatica extract containing bilayered electrospun wound dressing(Abdullah Gül Üniversitesi, 2019) KOÇ, NURAY; İşoğlu, İsmail AlperInnovative and bioactive wound dressings prepared by electrospinning mimicking the native structure of the extracellular matrix (ECM) have gained significant interest as an alternative to conventional wound care applications. In this study, bilayered wound dressing material was produced by sequential electrospinning of quaternized poly(4- vinyl pyridine) (upper layer) on the Centella Asiatica (CA) extract containing electrospun poly(D, L-lactide-co-glycolide) (PLGA)/poly(3-hydroxybutyrate-co-3- hydroxy valerate) (PHBV) blend membrane (lower layer). Scanning electron microscopy (SEM) was utilized to show a uniform and bead-free fiber structure of electrospun membranes. The average diameter of CA extract containing electrospun PLGA/PHBV blend membrane was calculated 0.471±0.11 µm, whereas the average fiber diameter of electrospun poly(Q-VP) membranes was in the range of 0.460±0.057 µm. Chemical, thermal, mechanical properties, and adsorption capacity of electrospun membranes, as well as the cumulative release of CA from the electrospun PLGA/PHBV membrane, were investigated. Viability, adhesion, and attachment of human fibroblast cells on the electrospun membranes on pre-set days were evaluated by the colorimetric CellTiter 96® Aqueous One Solution Cell Proliferation Assay (MTS assay) and SEM. Results revealed that CA loaded bilayered electrospun wound dressing showed promoted attachment and proliferation of fibroblasts. Hence, it can be concluded that CA extract containing bilayered electrospun wound dressing prepared in this study has a promising potential for wound healing applications.Research Project Bor Zengini Amorf Malzemeler(TUBİTAK, 2020) Durandurdu, MuratBu TÜBİTAK 1001 projesi kapsamında, bor zengini farklı amorf malzemeler [B1-xSix, B1-xCx, B1-_x000D_ xOx, ve B1-xLix (0, 5 ≥ � ≥ 0,05)] ab initio moleküler dinamik tekniği kullanılarak sıvı hallerin hızlıca_x000D_ soğutulması sonucu modellenmiş ve bu malzemelerin atomik yapıları, elektronik yapıları ve_x000D_ mekanik özellikleri ayrıntı olarak araştırılmıştır. Bunlara ek olarak, bu malzemelerin bazı_x000D_ oranlarının yüksek basınçtaki davranışları incelenmiştir. Bazı malzemelerde, örneğin BC ve BO_x000D_ malzemelerinde, bor oranının artmasıyla iki boyutlu yapıdan üç boyutlu yapıya geçiş_x000D_ gözlemlenmiştir. Ayrıca yüksek bor oranlarında, B12 icosahedralların oluştuğu bulunmuştur. B12_x000D_ molekülüne ek olarak nano boyutunda B7, B10, B14, B16 kafes moleküllerinin oluşumu bazı_x000D_ malzemelerde gözlemlenmiştir. Modellenen malzemelerin her birinin yarıiletken özelliği gösterdiği_x000D_ fakat yasak band aralığında bor oranına bağlı genel bir eğilim olmayıp dalgalanmaların olduğu_x000D_ bulunmuştur. B12 moleküllerinin oluşumunun malzemelerin mekanik özelliğini dikkate değer bir_x000D_ şekilde etkilediği ve bor oranı yüksek olan malzemelerin daha sert bir özellik gösterdiği_x000D_ bulunmuştur. Yüksek basınç uygulamasıyla, malzemelerin daha yoğun bir amorf yapıya faz_x000D_ geçişişi yaptığı ve malzemeye bağlı olarak, faz geçişlerinin tersinir ya da tersinir olmayan faz_x000D_ geçişleri olduğu gözlemlenmiştir.Doctoral Thesis A reliable and secure communication design for underwater sensor networks concerning energy efficiency(Abdullah Gül Üniversitesi, Fen Bilimleri Enstitüsü, 2023) UYAN, Osman Gökhan; Güngör, Vehbi ÇağrıUnderwater Acoustic Sensor Networks (UASNs) recently attract scientists because of its wide range of applications and emerging technology. A design challenge in UASN's is the limited network lifetime and poor reliability caused by limited battery supply of sensors and harsh channel conditions in underwater environment. Moreover, sensors might transmit sensitive data that must be disguised against eavesdropping attacks. To maintain a reliability level, packet-duplication and multi-path routing method are suggested, which renders eavesdropping attacks easier. For data security, cryptographic encryption is the most acclaimed method. However, encryption needs extra computations, which consume extra energy and cause a decrease in the network lifetime. As a countermeasure along with encryption against silent listening, fragmenting data and transmitting in pieces over different paths has been proposed. To address these challenges, an optimization framework has been developed to analyze the effects of multi-path routing, packet duplication, encryption, and data fragmentation on network lifetime. However, the solution time of the proposed optimization model is quite high, and sometimes it cannot come up with feasible solutions. To this end, in this study, different regression and neural network methods have been proposed to predict the energy consumptions of underwater nodes as supplementary methods to optimization models. Performance evaluations show that the proposed methods yield remarkably accurate predictions and can be used for energy consumption prediction in UASNs.Article Citation - WoS: 38Citation - Scopus: 38pH- and Temperature-Responsive Amphiphilic Diblock Copolymers of 4-Vinylpyridine and Oligoethyleneglycol Methacrylate Synthesized by RAFT Polymerization(Elsevier Sci Ltd, 2014-01) Topuzogullari, Murat; Bulmus, Volga; Dalgakiran, Eray; Dincer, SevilDiblock copolymers of 4-vinylpyridine (4VP) and oligoethyleneglycol methyl ether methacrylate (OEGMA) were synthesized for the first time using RAFT polymerization technique as potential drug delivery systems. Effects of the number of ethylene glycol units in OEGMA, chain length of hydrophobic P4VP block, pH, concentration and temperature on the solution behavior of the copolymers were investigated comprehensively. Copolymer chains formed micelles at pH values higher than 5 whereas unimeric polymers were observed to exist below pH 5, owing to the repulsion between positively charged P4VP blocks. The size of the micelles was dependent on the relative length of blocks, P4VP and POEGMA. Thermo-responsive properties of copolymers were investigated depending on the pH and length of P4VP block. The increase in the length of P4VP block decreased the LCST substantially at pH 7. At pH 3, LCST of copolymers shifted to higher temperatures due to the increased interaction of copolymers with water through positively charged P4VP block. (C) 2013 Elsevier Ltd. All rights reserved.Article Citation - WoS: 26Citation - Scopus: 33miRmoduleNet: Detecting miRNA-mRNA Regulatory Modules(Frontiers Media S.A., 2022-04-12) Yousef, Malik; Goy, Gokhan; Bakir-Gungor, BurcuIncreasing evidence that MicroRNAs (miRNAs) play a key role in carcinogenesis has revealed the need for elucidating the mechanisms of miRNA regulation and the roles of miRNAs in gene-regulatory networks. A better understanding of the interactions between miRNAs and their mRNA targets will provide a better understanding of the complex biological processes that occur during carcinogenesis. Increased efforts to reveal these interactions have led to the development of a variety of tools to detect and understand these interactions. We have recently described a machine learning approach miRcorrNet, based on grouping and scoring (ranking) groups of genes, where each group is associated with a miRNA and the group members are genes with expression patterns that are correlated with this specific miRNA. The miRcorrNet tool requires two types of -omics data, miRNA and mRNA expression profiles, as an input file. In this study we describe miRModuleNet, which groups mRNA (genes) that are correlated with each miRNA to form a star shape, which we identify as a miRNA-mRNA regulatory module. A scoring procedure is then applied to each module to further assess their contribution in terms of classification. An important output of miRModuleNet is that it provides a hierarchical list of significant miRNA-mRNA regulatory modules. miRModuleNet was further validated on external datasets for their disease associations, and functional enrichment analysis was also performed. The application of miRModuleNet aids the identification of functional relationships between significant biomarkers and reveals essential pathways involved in cancer pathogenesis.Article Citation - WoS: 20Citation - Scopus: 24miRdisNET: Discovering MicroRNA Biomarkers That Are Associated With Diseases Utilizing Biological Knowledge-Based Machine Learning(Frontiers Media S.A., 2023-01-12) Jabeer, Amhar; Temiz, Mustafa; Bakir-Gungor, Burcu; Yousef, MalikDuring recent years, biological experiments and increasing evidence have shown that MicroRNAs play an important role in the diagnosis and treatment of human complex diseases. Therefore, to diagnose and treat human complex diseases, it is necessary to reveal the associations between a specific disease and related miRNAs. Although current computational models based on machine learning attempt to determine miRNA-disease associations, the accuracy of these models need to be improved, and candidate miRNA-disease relations need to be evaluated from a biological perspective. In this paper, we propose a computational model named miRdisNET to predict potential miRNA-disease associations. Specifically, miRdisNET requires two types of data, i.e., miRNA expression profiles and known disease-miRNA associations as input files. First, we generate subsets of specific diseases by applying the grouping component. These subsets contain miRNA expressions with class labels associated with each specific disease. Then, we assign an importance score to each group by using a machine learning method for classification. Finally, we apply a modeling component and obtain outputs. One of the most important outputs of miRdisNET is the performance of miRNA-disease prediction. Compared with the existing methods, miRdisNET obtained the highest AUC value of .9998. Another output of miRdisNET is a list of significant miRNAs for disease under study. The miRNAs identified by miRdisNET are validated via referring to the gold-standard databases which hold information on experimentally verified MicroRNA-disease associations. miRdisNET has been developed to predict candidate miRNAs for new diseases, where miRNA-disease relation is not yet known. In addition, miRdisNET presents candidate disease-disease associations based on shared miRNA knowledge. The miRdisNET tool and other supplementary files are publicly available at: .