Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/11

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Now showing 1 - 10 of 10
  • Article
    Experimental Investigation of Refractive Index Measurement of Common Solvents and Aqueous Solutions in the Infrared Wavelengths
    (2018) Yüksel, K.; İde, C
    We proposed and experimentally demonstrated a fast and simple technique to measure refractive index of liquids. A commercial Optical Time-Domain Reflectometer (OTDR) was implemented for interrogating sensor tips from a remote location. The system uses Fresnel reflected light from standard single mode fiber tips as sensing points without requiring any chemical coating, delicate fiber components, and/or sophisticated architecture at the sensor head. We reported new measurements of refractive indices of common solvents and solutions at both 1550 nm and 1625 nm. The precision of the proposed measurement system was found to be in the order of 10-4. The experimental results have been validated by the way of theoretical calculations.
  • Research Project
    Farklı kontraslı medikal görüntülerin bilgi teorisi kaynaklı nokta benzerliği ölçütleriyle elastik olarak hizalanması
    (2011) Karaçalı, Bilge
    Medikal görüntülerin elastik olarak hizalanması, şizofreni, Alzheimer hastalığı gibi birçok nörolojik bozukluğun daha iyi anlaşılmasına olanak veren işlemsel anatomi yöntemlerinin temelini oluşturmaktadır. Hizalanmak istenen görüntülerdeki benzer parlaklık gösteren ortak yapıları arayıp örtüştürme esasına dayanan bu yöntemler, görüntüler arasında kontrast farklılıkları olduğu durumlarda ise istenen başarıyı sağlayamamaktadırlar. Bu projede, farklı kontrast özelliklerine sahip medikal görüntüleri bilgisayar ortamında elastik olarak hizalayan bir algoritma geliştirilmiştir. Bu amaç dahilinde öncelikle görüntüler arasında eşlenik noktaları ve bu noktalardaki eşlenik yönelimleri belirleyen ve daha sonra bu noktalara dayanarak yoğun deformasyon alanları oluşturan iki ana işlem modülü türetilmiştir. Bu modüller daha sonra çok katmanlı bir platform üzerinde çalışan döngülü bir yapıda birleştirilmiştir. Bu şekilde türetilen algoritma, sağladığı hizalama başarısı açısından sınanmıştır. Farklı kontrastlı görüntülerin hizalanması, işlemsel anatomi yöntemlerinin, ideal ve birbiri ile uyumlu kontrast özelliklerinin aranamayacağı geniş kapsamlı çalışmalarda uygulanmasına olanak sağlamıştır. Bu projede geliştirilmiş olan bu algoritma, ileride geniş katılımcı grupları ile yürütülecek beyin araştırmalarında, özellikle kontrast farklılıklarının olağan olarak gözlendiği multipl skleroz gibi nörodejeneratif bozuklukların konu alındığı çalışmalarda taranan görüntülerin değerlendirilmesinde işlemsel yapı taşı olarak işlev görecektir. Bu sayede hem bölgesel koşullarda bu hastalıkların gelişimi ve tanısal özellikleri çok daha detaylı bir biçimde incelenebilecek, hem de benzer çalışmalara destek verecek işlemsel bir merkez oluşturulmasına katkı sağlanmış olacaktır.
  • Conference Object
    Citation - Scopus: 1
    3-D Switching Fabric Node Design
    (ACTA Press, 2004) Dinleyici, Mehmet Salih; Akın, Osman
    In this work we investigate an all-optical switching node that can be controlled by means of a transient grating, which is formed by interference of two Gaussian beams. This design considers 3-D architecture of switching fabrics.. real profile of Gaussian beams and fast switching time requirements. Four Wave Mixing (FWM) technique is applied in the evanescent field region of waveguide, showing chi((3)) nonlinearity. The formed grating is analysed by standart methods to obtain reflection coefficient and then coupling coefficient for power exchange between waveguides.
  • Conference Object
    Detection of Urban Change Using Remote Sensing and Gis: Izmir Case
    (Taylor and Francis Ltd., 2008) Tarhan, Çiğdem; Arkon, Cemal; Çelik, M.; Gümüştekin, Şevket; Tecim, V.
    This study is an example of how land use changes could be detected via high resolution remotely sensed data. In order to perform "change detection" IKONOS satellite images, belonging to 2001 and 2004, have been used. An automated Graphical User Interface (GUI) has been created for detection of environment. Different image enhancement techniques and a fuzzy inference system have been combined in the GUI. The detection results are classified according to some basic levels such as 20-50% and 70%. Additionally, four different change detection algorithms have been applied which are pixel-based, object based, feature based. These algorithms have been examined according to change detection levels with different image enhancement techniques. At the end of the study, the results have been compared.
  • Conference Object
    Citation - WoS: 1
    Distance Measurement by Means of a Groove Guide Oscillator
    (Electromagnetics Academy, 2009) Bechteler, Thomas F.; Aydınlık Bechteler, Ayşe Sevinç
    In this work, a system for measuring the distance between two metallic plates is presented. A groove guide resonator operating in the X-band with an incorporated Gunn element serves as the distance sensor. According to the distance between the two metallic plates, the resonant frequencies of the groove guide oscillator change. In a first step, the fundamental resonant frequency of the groove guide oscillator at various distances is computed by means of the FDTD (Finite Difference Time Domain) method. In a second step, the resonant frequencies of the realized groove guide oscillator were measured. Although the signal's wavelength is about 30 mm, the resolution of the measurement is in the sub-millimeter level, i.e., about 25 mu m. Furthermore, in case of distance variations, even within a short time, the system is able to track distance variations nearly instantaneously. The resonant frequency information is processed using a heterodyne system.
  • Conference Object
    Citation - Scopus: 8
    Localization of a Passive Molecular Transmitter With a Sensor Network
    (Springer, 2020) Güleç, Fatih; Atakan, Barış
    Macroscale molecular communication (MC), which has a potential for practical applications, is a promising area for communication engineering. In a practical scenario such as monitoring air pollutants released from an unknown source, it is essential to estimate the location of the molecular transmitter (TX). This paper presents a novel Sensor Network-based Localization Algorithm (SNCLA) for passive transmission by using a novel experimental platform which mainly comprises a clustered sensor network (SN) with 24 sensor nodes and evaporating ethanol molecules as the passive TX. With the usage of the SN concept, novel methods can be developed for the problems in macroscale MC by utilizing the wide literature of sensor networks. In SNCLA, Gaussian plume model is employed to derive the location estimator. The parameters such as transmitted mass, wind velocity, detection time and actual concentration are calculated or estimated from the measured signals via the SN to be employed as the input for the location estimator. The numerical results show that the performance of SNCLA is better for stronger winds in the medium. Our findings show that evaporated molecules do not propagate homogeneously through the SN due to the presence of the wind. In addition, the estimation error of SNCLA decreases for higher detection threshold values. © 2020, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.
  • Conference Object
    Citation - Scopus: 1
    Hierarchical Motif Vectors for Amino Acid Sequence Alignment
    (2012) Karaçalı, Bilge
    We present a new framework for global and local alignment of amino acid sequences based on hierarchical motif vectors that characterize local amino acid configurations. The motif vectors are constructed by carrying out wavelet decomposition on numeric property sequences obtained by replacing each amino acid in a sequence with their respective properties, and concatenating such profiles obtained for a large number of physico-chemical properties into a single column vector. We then formulate different schemes for aligning amino acid sequences based on their respective motif vectors globally as well as locally subject to measures of statistical significance. Experiment results indicate that the motif vectors accurately capture the amino acid composition at and around individual sites along sequences and allow associating sequence segments sharing similar functional attributes.
  • Book
    Citation - Scopus: 17
    Feedback Strategies for Wireless Communication
    (Springer, 2014) Özbek, Berna; Le Ruyet, Didier
    This book explores the different strategies regarding limited feedback information. The book analyzes the impact of quantization and the delay of CSI on the performance. The author shows the effect of the reduced feedback information and gives an overview about the feedback strategies in the standards. This volume presents theoretical analysis as well as practical algorithms for the required feedback information at the base stations to perform adaptive resource algorithms efficiently and mitigate interference coming from other cells. © 2014 Springer Science+Business Media New York. All rights are reserved.
  • Book
    Citation - Scopus: 37
    Molecular Communications and Nanonetworks: From Nature To Practical Systems
    (Springer, 2014) Atakan, Barış
    This book will introduce the concept of molecular communications and nanonetworks. The publication addresses why nanoscale communication is needed for the sophisticated nano and biotechnology applications. The text introduces the frontier applications of the molecular communication and nanonetworks. The book examines the molecular communication types called active, passive, and gap junction molecular communications. The author presents the molecular transmitter, receiver, encoding and decoding mechanisms used in these systems. Discussing the molecular communication system model and looking at the unique characteristics of practical molecular communication systems and these chemical reactions and their effects on the communication performance. Finally, the book examines the point-to-point, broadcast, and multiple-access molecular channel and shows two promising application examples of the nanonetworks. The first application example is the body area nanonetworks used in nanomedicine. the second nanonetwork application example, i.e., NanoSensor Networks (NSNs) with Molecular Communication. © Springer Science+Business Media New York 2014.
  • Conference Object
    Citation - Scopus: 1
    Fs Fbgs as Probes To Monitor Thermal Regeneration Mechanisms
    (SPIE, 2019) Chah, K.; Kinet, D.; Yüksel, Kıvılcım; Caucheteur, C.
    This paper shows that fiber Bragg gratings written in standard single mode optical fiber with IR femtosecond pulses and point-by-point technique are high temperature resistant (< 1000 degrees C). Moreover, after calibration process, these gratings can be used as a reference to study and discriminate between different high temperature annealing mechanisms involved in other types of gratings and/or fibers. Here we have considered the regeneration process of gratings written by UV laser in boron/germanium co-doped single mode optical fiber. Hence, the monitoring of grating strength and differential wavelength shift between femtosecond and type-I gratings during annealing cycle yields the wavelength shift due to the annealing of doping (mainly boron) and UV-related defects and their relative contributions to the regeneration mechanism.