Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Article Citation - WoS: 4Citation - Scopus: 4Adaptive Visual Servo Regulation Control for Camera-In Configuration With a Fixed Camera Extension(ACTA Press, 2009) Tatlıcıoğlu, Enver; Dawson, Darren M.; Xian, B.In this paper, image-based regulation control of a robot manipulator with an uncalibrated vision system is discussed. To compensate for the unknown camera calibration parameters, a novel prediction error formulation is presented. To achieve the control objectives, a Lyapunov-based adaptive control strategy is employed. The control development for the camera-in-hand problem is presented in detail and a fixed-camera problem is included as an extension.Conference Object Index Modulation of Transient Grating in Nonlinear Medium(SPIE, 2016) Karakılınç, Özgür Önder; Dinleyici, Mehmet SalihA transient chirped grating structure is formed by beam interferences in nonlinear photonic crystal waveguide. Pulse propagation in nonlinear transient grating media is investigated and its impact on the transmission dynamics is explored. The grating may not be stationary propagating but anharmonically oscillating. Thus, effective modification of the refractive index needs to be evaluated in detail.Conference Object Citation - Scopus: 1Fs 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.Article Citation - WoS: 1Citation - Scopus: 1Temperature and Pressure Dependence of the Raman Intensity and Frequency of a Soft Mode Near the Tricritical Point in the Ferroelectric Sbsi(Taylor & Francis, 2016) Yurtseven, Hasan Hamit; Duman, SinemWe analyze the pressure dependence of the intensity and the frequency of a soft mode from the Raman and elastic light scattering experiments as reported in the literature close to the ferroelectric - paraelectric transition in SbSI crystal. The Raman intensity of this mode is analyzed as a function of pressure at constant temperatures of 272K (first order transition) and 234K (tricritical or second order transition) according to a power-law formula. Our analysis of the Raman intensity gives closely the mean field values for the order parameter. From our analysis, we also obtain that the Raman frequency (squared) of the soft mode varies linearly with the pressure at constant temperatures close to the ferroelectric - paraelectric transition in SbSI as obtained experimentally.Conference Object Kahve Laboratory Rf Circulator and Transmission Line Project(American Institute of Physics, 2018) Çetinkaya, Hakan; Çağlar, Aslıhan; Çicek, Cihan; Özbey, Aydın; Sunar, Ezgi; Türemen, Görkem; Yıldız, Hüseyin; Yüncü, Alperen; Özcan, Erkcan; Ünel, Gökhan; Yaman, FatihAn 800 MHz RF circulator and transmission line project has recently started at the newly commissioned Kandilli Detector, Accelerator and Instrumentation (KAHVE) Laboratory at the Boǧaziçi University. The aims are to design, build and construct an RF circulator and transmission line in Turkey for high power and high frequency applications. The project consists of 8 transmission line elements: 800 MHz RF generator with 60 kW power (klystron), klystron to waveguide converter, waveguides, E and H bends, 3-port circulator and waveguide to coaxial converter to transmit RF power to a pillbox RF cavity. Design studies and details of the ongoing project will be presented.Conference Object Approximate Best Linear Unbiased Channel Estimation for Multi-Antenna Frequency Selective Channels With Applications To Digital Tv Systems(SPIE, 2004) Özen, Serdar; Pladdy, Christopher; Nerayanuru, Sreenivasa M.; Fimoff, Mark J.; Zoltowski, Michael D.We provide an iterative and a non-iterative channel impulse response (CIR) estimation algorithm for communication receivers with multiple-antenna. Our algorithm is best suited for communication systems which utilize a periodically transmitted training sequence within a continuous stream of information symbols, and the receivers for this particular system are expected work in a severe frequency selective multipath environment with long delay spreads relative to the length of the training sequence. The iterative procedure calculates the (semi-blind) Best Linear Unbiased Estimate (BLUE) of the CIR. The non-iterative version is an approximation to the BLUE CIR estimate, denoted by a-BLUE, achieving almost similar performance, with much lower complexity. Indeed we show that, with reasonable assumptions, a-BLUE channel estimate can be obtained by using a stored copy of a pre-computed matrix in the receiver which enables the use of the initial CIR estimate by the subsequent equalizer tap weight calculator. Simulation results are provided to demonstrate the performance of the novel algorithms for 8-VSB ATSC Digital TV system. We also provide a simulation study of the robustness of the a-BLUE algorithm to timing and carrier phase offsets.Article Citation - WoS: 3Citation - Scopus: 3Texture Analysis of Polymer Modified Bitumen Images(Carl Hanser Verlag GmbH & Co. KG, 2011) Gümüştekin, Şevket; Topal, Ali; Şengöz, BurakThis study aims to analyze the textural features extracted from microscopic images of elastomeric and plastomeric type polymer modified bitumen (PMB) including five different types and contents of polymers. Fluorescence microscopy was used to capture microscopic images from thin films of PMB samples at different magnification scales (400×, 100×, and 40×). Gabor filters were utilized to extract the textural features of bitumen images. The features were used in three different query tests to quantify their representation capacity. The K nearest neighbor classifier was tested using leave-one-out cross validation. Textural analysis on the captured images provided numerical results that are in compliance with subjective visual tests. © 2011 Carl Hanser Verlag, Munich, Germany.Article Citation - WoS: 10Citation - Scopus: 10On the Helmholtz Theorem and Its Generalization for Multi-Layers(Taylor and Francis Ltd., 2016) Kuştepeli, AlpThe decomposition of a vector field to its curl-free and divergence-free components in terms of a scalar and a vector potential function, which is also considered as the fundamental theorem of vector analysis, is known as the Helmholtz theorem or decomposition. In the literature, it is mentioned that the theorem was previously presented by Stokes, but it is also mentioned that Stokes did not introduce any scalar and vector potentials in his expressions, which causes a contradiction. Therefore, in this article, Stokess and Helmholtzs representations are examined in detail to reveal and emphasize their differences, similarities and important points. The Helmholtz theorem is obtained for all kinds of spaces by using the theory of distributions in a comprehensive and rigorous manner with detailed explanations, which also leads to a new surface version of the Helmholtz theorem or a new surface decomposition, resulting in the canonical form; hence, it is different than the one suggested previously in terms of two scalar functions. The generalized form of the Helmholtz theorem is also presented by employing the same approach when there is a multi-layer on the surface of discontinuity, which also corresponds to the extension of the theorem to fields with singularities of higher order.Conference Object Citation - WoS: 1Citation - Scopus: 2Fisher's Linear Discriminant Analysis Based Prediction Using Transient Features of Seismic Events in Coal Mines(Institute of Electrical and Electronics Engineers Inc., 2016) Köktürk Güzel, Başak Esin; Karaçalı, BilgeIdentification of seismic activity levels in coal mines is important to avoid accidents such as rockburst. Creating an early warning system that can save lives requires an automated way of predicting. This study proposes a prediction algorithm for the AAIA'16 Data Mining Challenge: Predicting Dangerous Seismic Events in Active Coal Mines that is based on transient activity features along with average indicators evaluated by a Fisher's linear discriminant analysis. Performance evaluation experiments on the training datasets revealed an accuracy level of around 0.9438 while the performance on the test dataset was at a level of 0.9297. These results suggest that the proposed approach achieves high accuracy in predicting danger seismic events while maintaining low complexity.Article Citation - WoS: 1Citation - Scopus: 1Revised Distributional Forms of the Laplacian and Poisson's Equation, Their Implications, and All Related Generalizations(Taylor and Francis Ltd., 2015) Kuştepeli, AlpThe theory of distributions of L. Schwartz is a very useful and convenient way for the analysis of physical problems since physical distributions, especially charge distributions yielding the discontinuity of the potential and boundary conditions, can be correctly described in terms of mathematical distributions. To obtain the charge distributions, the distributional form of the Laplacian is applied to the Poisson's equation; therefore, for the correct representations and interpretations, the distributional forms and their proper applications are very important. In this article, it is shown that the distributional form of the Laplacian has been presented by Schwartz and also others with a missing term, leading to confusing and wrong results mathematically, and as a result electromagnetically; and the revised, correct, and complete distributional representations of the Laplace operator, the Poisson equation, and double layers, defined as the dipole layer and equidensity layer, are obtained and presented with detailed discussions and explanations including boundary conditions. By using the revised form of the Laplacian, Green's theorem is obtained explicitly with special emphases about important points and differences with previous works. The generalized forms of the Laplacian, Poisson's equation, charge densities, boundary conditions, and Greens theorem are also presented when there is a multi-layer on the surface of discontinuity.