Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Conference Object Citation - Scopus: 5Adaptive Visual Servo Regulation Control for Camera-In Configuration With a Fixed Camera Extension(Institute of Electrical and Electronics Engineers Inc., 2007) 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 All-Optical Switching Based on Grating Written Photorefractive Slab/Fiber Waveguide Coupler(Institute of Electrical and Electronics Engineers Inc., 2002) Dinleyici, Mehmet SalihSince all optical switching is a key element for all kinds of optical networks, great amount of works have been dedicated either for material researches or various waveguide structures. Generally speaking the switching time of devices based on photorefractive effect are rather slow for today's high capacity optical fiber networks. In the field of waveguide architecture various geometries have been proposed and investigated for grating assisted or guided optical coupling for the purpose of designing all-optical switch, adddrop multiplexers, filters etc.Conference Object Paralel Model Kombinasyonu ve Yerel Öznitelikler Kullanarak Gürbüz Konuşmacı Onaylama(Institute of Electrical and Electronics Engineers Inc., 2004) Tüfekçi, ZekeriyaInterfering noise severely degrades the performance of a speaker verification system. The Parallel Model Combination (PMC) technique is one of the most efficient techniques for dealing with such noise. Another method is to use features local in the frequency domain. Recently, we proposed Mel-Frequency Discrete Wavelet Coefficients (MFDWCs) [1] as speech features local in frequency domain. In this paper, we discuss using PMC along with MFDWC features to take advantage of both noise compensation and local features (MFDWCs) to decrease the effect of noise on verification performance. We evaluate the performance of MFDWCs for various noise types and noise levels. We also compare the performance of these versus MFCCs and both using PMC for dealing with additive noise. The experimental results show significant performance improvements for MFDWCs versus MFCCs after compensating the HMMs using the PMC technique. For example the MFDWCs gave 6.29 points performance improvement on average over MFCCs for 12 dB. This corresponds to 38.33% error reduction.Conference Object Citation - Scopus: 13-D Switching Fabric Node Design(ACTA Press, 2004) Dinleyici, Mehmet Salih; Akın, OsmanIn 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: 15Citation - Scopus: 20Adaptive Control of Redundant Robot Manipulators With Sub-Task Objectives [proceedings Paper](Institute of Electrical and Electronics Engineers Inc., 2008) Tatlıcıoğlu, Enver; Braganza, David; Burg, Timothy C.; Dawson, Darren M.In this paper, adaptive control of kinematically redundant robot manipulators is considered. An end-effector tracking controller is designed and the manipulator's kinematic redundancy is utilized to integrate a general sub-task controller for self-motion control. The control objectives are achieved by designing a feedback linearizing controller that includes a least-squares estimation algorithm to compensate for the parametric uncertainties.Conference Object Spin Polarized Tunneling in Large Area Mesas of Superconducting Bi 2sr2cacu2o8+δ for the Generation of the Thz Waves(Institute of Electrical and Electronics Engineers Inc., 2009) Türkoğlu, Fulya; Şimşek, Yılmaz; Köseoğlu, Hasan; Demirhan, Yasemin; Meriç Polster, Zeynep; Özyüzer, LütfiRectangular intrinsic Josephson junction mesa structures of superconducting Bi2Sr2CaCu2O8+delta (Bi2212) can be used as a source of continuous, coherent and polarized terahertz (THz) radiation. THz emitting mesas are below a certain underdoped level of Bi2212. They have small Josephson critical current in contrast to optimally doped and overdoped Bi2212. We deposited Au/Co/Au multilayer top of mesa and obtained small critical current from mesas fabricated by as-grown Bi2212 single crystals due to injection of spin polarized current. The spin injection eliminates adjustment of doping level for successful THz emission.Conference Object Citation - WoS: 1Distance Measurement by Means of a Groove Guide Oscillator(Electromagnetics Academy, 2009) Bechteler, Thomas F.; Aydınlık Bechteler, Ayşe SevinçIn 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.Article Citation - WoS: 18Citation - Scopus: 31Applied Mel-Frequency Discrete Wavelet Coefficients and Parallel Model Compensation for Noise-Robust Speech Recognition(Elsevier, 2006) Tüfekçi, Zekeriya; Gowdy, John N.; Gürbüz, Sabri; Patterson, EricInterfering noise severely degrades the performance of a speech recognition system. The Parallel Model Compensation (PMC) technique is one of the most efficient techniques for dealing with such noise. Another approach is to use features local in the frequency domain, such as Mel-Frequency Discrete Wavelet Coefficients (MFDWCs). In this paper, we investigate the use of PMC and MFDWC features to take advantage of both noise compensation and local features (MFDWCs) to decrease the effect of noise on recognition performance. We also introduce a practical weighting technique based on the noise level of each coefficient. We evaluate the performance of several wavelet-schemes using the NOISEX-92 database for various noise types and noise levels. Finally, we compare the performance of these versus Mel-Frequency Cepstral Coefficients (MFCCs), both using PMC. Experimental results show significant performance improvements for MFDWCs versus MFCCs, particularly after compensating the HMMs using the PMC technique. The best feature vector among the six MFDWCs we tried gave 13.72 and 5.29 points performance improvement, on the average, over MFCCs for -6 and 0 dB SNR, respectively. This corresponds to 39.9% and 62.8% error reductions, respectively. Weighting the partial score of each coefficient based on the noise level further improves the performance. The average error rates for the best MFDWCs dropped from 19.57% to 16.71% and from 3.14% to 2.14% for -6 dB and 0 dB noise levels, respectively, using the weighting scheme. These improvements correspond to 14.6% and 31.8% error reductions for -6 dB and 0 dB noise levels, respectively. (c) 2006 Elsevier B.V. All rights reserved.Article Citation - WoS: 67Citation - Scopus: 78Chirp Group Delay Analysis of Speech Signals(Elsevier, 2007) Bozkurt, Barış; Couvreur, Laurent; Dutoit, ThierryThis study proposes new group delay estimation techniques that can be used for analyzing resonance patterns of short-term discrete-time signals and more specifically speech signals. Phase processing or equivalently group delay processing of speech signals are known to be difficult due to large spikes in the phase/group delay functions that mask the formant structure. In this study, we first analyze in detail the z-transform zero patterns of short-term speech signals in the z-plane and discuss the sources of spikes on group delay functions, namely the zeros closely located to the unit circle. We show that windowing largely influences these patterns, therefore short-term phase processing. Through a systematic study, we then show that reliable phase/group delay estimation for speech signals can be achieved by appropriate windowing and group delay functions can reveal formant information as well as some of the characteristics of the glottal flow component in speech signals. However, such phase estimation is highly sensitive to noise and robust extraction of group delay based parameters remains difficult in real acoustic conditions even with appropriate windowing. As an alternative, we propose processing of chirp group delay functions, i.e. group delay functions computed on a circle other than the unit circle in z-plane, which can be guaranteed to be spike-free. We finally present one application in feature extraction for automatic speech recognition (ASR). We show that chirp group delay representations are potentially useful for improving ASR performance. (c) 2007 Elsevier B.V. All rights reserved.