Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

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

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2-D Thresholding of the Connectivity Map Following the Multiple Sequence Alignments of Diverse Datasets
(ACTA Press, 2013) Doğan, Tunca; Karaçalı, Bilge; Karaçalı, Bilge; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Multiple sequence alignment (MSA) is a widely used method to uncover the relationships between the biomolecular sequences. One essential prerequisite to apply this procedure is to have a considerable amount of similarity between the test sequences. It's usually not possible to obtain reliable results from the multiple alignments of large and diverse datasets. Here we propose a method to obtain sequence clusters of significant intragroup similarities and make sense out of the multiple alignments containing remote sequences. This is achieved by thresholding the pairwise connectivity map over 2 parameters. The first one is the inferred pairwise evolutionary distances and the second parameter is the number of gapless positions on the pairwise comparisons of the alignment. Threshold curves are generated regarding the statistical parameter values obtained from a shuffled dataset and probability distribution techniques are employed to select an optimum threshold curve that eliminate as much of the unreliable connectivities while keeping the reliable ones. We applied the method on a large and diverse dataset composed of nearly 18000 human proteins and measured the biological relevance of the recovered connectivities. Our precision measure (0.981) was nearly 20% higher than the one for the connectivities left after a classical thresholding procedure displaying a significant improvement. Finally we employed the method for the functional clustering of protein sequences in a gold standard dataset. We have also measured the performance, obtaining a higher F-measure (0.882) compared to a conventional clustering operation (0.827).
Active Eye-Glasses With Local Dimming
(Institute of Electrical and Electronics Engineers Inc., 2011) Özvural, Görkem; Gümüştekin, Şevket; Gümüştekin, Şevket; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The sense of sight provides the most reliable information about the environment. Although the human eye has a wide dynamic range for brightness adaptation, direct exposure to relatively bright light sources wipes out the total visual perception. The most remarkable example of this situation is driving a car at night, while the other cars are coming from the opposite lane with headlights on. In this work, we have proposed and developed a set of LCD equipped active glasses to solve this light adaptation problem. First, the location of the light sources are determined using an on board camera which is assembled in front of the glasses. After processing image data, the locations of the bright light sources are darkened and the disturbing effect of intense light sources is reduced. © 2011 Chamber of Turkish Electric.
Citation - Scopus: 2
Adaptive Bit Partitioning Strategy for Cell-Edge Users in Multi-Antenna Multicell Networks
(Institute of Electrical and Electronics Engineers Inc., 2011) Özbek, Berna; Özbek, Berna; Le Ruyet, Didier; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this paper, we improve the performance of cell-edge users by applying adaptive bit partitioning for intercell interference cancelation in cooperative downlink multicell systems. The strategy for partitioning quantization bits between serving and interfering base stations affects the performance of the cooperative networks which is quite sensitive to the quality of the channel state information. The existing transmission strategies are based on the maximization of average cell rate which results in a reduced rate for the users in the cell-edge regions. We propose an adaptive bit partitioning strategy to improve the rate of cell-edge users at the same average feedback link rate. We show the performance of the cell-edge users is significantly increased while keeping the same average cell rate. © 2011 IEEE.
Citation - WoS: 1
Citation - Scopus: 7
The Adaptive Channel Estimation for Stbc-Ofdm Systems
(İstanbul Üniversitesi, 2005) Özbek, Berna; Özbek, Berna; Yılmaz, Reyat; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this paper, we propose adaptive channel estimation methods based on LMS and RLS for orthogonal STBC-OFDM systems with three transmit antennas. The performance of the proposed algorithms is obtained in the frequency selective channels using Hiperlan/2 characteristics.
Citation - WoS: 43
Citation - Scopus: 48
Adaptive Control of Redundant Robot Manipulators With Sub-Task Objectives
(Cambridge University Press, 2009-10) Tatlıcıoğlu, Enver; Tatlıcıoğlu, Enver; Braganza, David; Burg, Timothy C.; Dawson, Darren M.; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
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. Numerical simulation results are presented to show the validity of the proposed controller.
Citation - WoS: 15
Citation - Scopus: 20
Adaptive Control of Redundant Robot Manipulators With Sub-Task Objectives [proceedings Paper]
(Institute of Electrical and Electronics Engineers Inc., 2008) Tatlıcıoğlu, Enver; Tatlıcıoğlu, Enver; Braganza, David; Burg, Timothy C.; Dawson, Darren M.; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
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.
Citation - Scopus: 5
Adaptive Limited Feedback for Intercell Interference Cancelation in Cooperative Downlink Multicell Networks
(Institute of Electrical and Electronics Engineers Inc., 2010) Özbek, Berna; Özbek, Berna; Le Ruyet, Didier; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this paper, we evaluate intercell interference cancelation techniques in cooperative downlink multicell systems. We compare two classical beamforming strategies for the design of the beamforming vectors: maximum ratio combining precoding and partial zero-forcing. Since full channel state information at the transmission is unfeasible, we consider a limited feedback link and compare different strategies for bit partitioning of the feedback information for serving and interferer base stations. We propose a simple adaptive bit partitioning strategy to select an optimum transmission scheme at the base station. We show that the adaptive bit portioning algorithm is improved the sum capacity performance of the multicell networks significantly.
Citation - WoS: 6
Citation - Scopus: 9
Adaptive Limited Feedback Links for Cooperative Multi-Antenna Multicell Networks
(Springer Verlag, 2014) Özbek, Berna; Özbek, Berna; Ruyet, Didier Le; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The overall performance of cooperative networks is quite sensitive to channel state information (CSI) of serving and interfering base stations (BSs) and affected strongly by quality of limited feedback links. In this paper, we propose two adaptive limited feedback strategies for intercell interference cancelation in multi-antenna multicell networks. The first proposed strategy is developed to improve average multicell capacity assuming a fixed rate feedback link. This algorithm is based on adaptation of the number of bits to quantize CSI of serving and interfering BSs according to transmitter power and location of the user in its own cell. The second proposed strategy is designed in a way to increase average capacity of cell-edge users assuming an adaptive rate feedback link. This algorithm is based on the idea of allocating more bits to quantize CSI of users at cell-edge regions while allocating less bits for users near the serving BS. We illustrate performance of the proposed feedback links for downlink cooperative multi-antenna multicell networks in wireless channels.
Citation - WoS: 6
Citation - Scopus: 8
Adaptive Output Tracking Control of a Surface Vessel
(Institute of Electrical and Electronics Engineers Inc., 2008) Lee, Dongbin; Tatlıcıoğlu, Enver; Tatlıcıoğlu, Enver; Burg, Timothy C.; Dawson, Darren M.; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this paper, the tracking control of a three degree-of-freedom marine vessel is examined. The novelty of this work is the transformation of the asymmetric inertia matrix into a symmetric, positive definite matrix. The asymmetry arises from the added mass common to practical surface vessels and creates a significant challenge for control design. The control design is further complicated by the parametric uncertainties in the dynamic model of the vessel. Two adaptive control schemes with a projection-based adaptation law are proposed: a full-state feedback controller and an output feedback controller. Both controllers are known to yield a uniformly ultimately bounded tracking result in the presence of parametric uncertainty. Numerical simulation results are shown to demonstrate the validity of the proposed controllers.
Citation - WoS: 4
Citation - Scopus: 7
Adaptive Reduced Feedback Links for Distributed Power Allocation in Multicell Miso-Ofdma Networks
(IEEE Computer Society, 2014-04) Özbek, Berna; Özbek, Berna; Le Ruyet, Didier; Pischella, Mylene; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
For multi-antenna Orthogonal Frequency-Division Multiple Access (OFDMA) based multicell networks, the channel state information (CSI) of all users is required to share among base stations in order to perform distributed power allocation. However, the amount of feedback increases with the number of users, base stations, subcarriers and antennas. Therefore, it is important to perform a selection at the user side to reduce the feedback load and the complexity of resource allocation. In this letter, we propose adaptive reduced feedback links by choosing the users based on their approximate signal to interference noise ratio (SINR) and their locations in the cell to satisfy users' rate constraints. We illustrate the performance results of reduced feedback links by employing distributed resource allocation with link adaptation.
Citation - WoS: 6
Citation - Scopus: 11
Adaptive Resource Allocation for Multicast Ofdm Systems With Multiple Transmit Antennas
(Institute of Electrical and Electronics Engineers Inc., 2006) Özbek, Berna; Özbek, Berna; Le Ruyet, Didier; Khiari, Hajer; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
We evaluate the impact of multiple transmit antennas on the performance of multicast OFDM systems by proposing a suboptimal low complexity algorithm. Associated with a powerful erasure code, it is possible to increase the data rate of multicast OFDM systems by selecting for each subcarrier to the users with a good channel condition. We show that the resource allocation which includes the precoding vector selection, subcarrier allocation and bit loading is a difficult optimization problem. We propose a suboptimal algorithm to solve this problem by avoiding the optimization to reduce complexity. When the users are not symmetrically distributed around the base station, we add a fair scheduler to guarantee that each user receives the same amount of data. We present simulation results where we compare the proposed multicast systems with the classical multicast OFDM systems. When the users are symmetrically distributed around the base station, the gain is rather small, whereas when the users are non-symmetrically distributed, the proposed algorithm outperforms OFDM systems with subcarrier allocation.
Citation - WoS: 2
Citation - Scopus: 2
Adaptive Resource Allocation for Sdma-Ofdma Systems With Genetic Algorithm
(Institute of Electrical and Electronics Engineers Inc., 2009) Özbek, Berna; Özbek, Berna; Le Ruyet, Didier; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this paper, we propose an adaptive resource allocation algorithm to maximize the sum data rate for spatial division multiplexing access (SDMA) orthogonal division multiple access (OFDMA) systems using genetic algorithm. We perform Zero forcing (ZF) beamforming at the transmitter constructing single and multiple beams for OFDMA systems with multiple transmit antennas. In order to reduce the complexity and convergence time of genetic algorithm (GA), we present an initial condition obtained by allocating the user to the subcarrier with maximum precoding gain. The proposed algorithm reduces the complexity without sacrificing the performance. We obtain the simulation results and compare them with the classical static and adaptive allocation methods. We show that the GA with the proposed initial condition increases the sum data rate compared to classical GA and reduces the convergence time significantly for SDMA-OFDMA systems.
Citation - WoS: 19
Citation - Scopus: 22
Adaptive Sign Algorithm for Graph Signal Processing
(Elsevier, 2022-06) Yan, Yi; Altınkaya, Mustafa Aziz; Kuruoğlu, Ercan Engin; Altınkaya, Mustafa Aziz; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Efficient and robust online processing techniques for irregularly structured data are crucial in the current era of data abundance. In this paper, we propose a graph/network version of the classical adaptive Sign algorithm for online graph signal estimation under impulsive noise. The recently introduced graph adaptive least mean squares algorithm is unstable under non-Gaussian impulsive noise and has high computational complexity. The Graph-Sign algorithm proposed in this work is based on the minimum dispersion criterion and therefore impulsive noise does not hinder its estimation quality. Unlike the recently proposed graph adaptive least mean pth power algorithm, our Graph-Sign algorithm can operate without prior knowledge of the noise distribution. The proposed Graph-Sign algorithm has a faster run time because of its low computational complexity compared to the existing adaptive graph signal processing algorithms. Experimenting on steady-state and time-varying graph signals estimation utilizing spectral properties of bandlimitedness and sampling, the Graph-Sign algorithm demonstrates fast, stable, and robust graph signal estimation performance under impulsive noise modeled by alpha stable, Cauchy, Student's t, or Laplace distributions.
Citation - Scopus: 5
Adaptive Visual Servo Regulation Control for Camera-In Configuration With a Fixed Camera Extension
(Institute of Electrical and Electronics Engineers Inc., 2007) Tatlıcıoğlu, Enver; Tatlıcıoğlu, Enver; Dawson, Darren M.; Xian, B.; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
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.
Algıda gecikme ve kısa-ömürlü senkronizasyon temelli yeni bir hayali motor aktivite tanıma yaklaşımı
(IEEE, 2023) Olcay, B. Orkan; Karaçalı, Bilge; Karaçalı, Bilge; Olcay, Bilal Orkan; 01.01. Units Affiliated to the Rectorate; 03.05. Department of Electrical and Electronics Engineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
This study proposes a novel approach for investigating a brain-computer interface that considers the temporal organization of brain activity, explicitly accounting for perception latency. To this end, we aligned the onset of task periods with the concurrence of left parietal and parieto-occipital electrodes to obtain the timings of perception latencies. Then, activity-specific synchronization timings between channel pairs were calculated using the time-aligned task periods. The perception latency and activity-specific synchronization timings were subsequently used for feature extraction and classification. The proposed approach achieved significantly better performance when comparing the proposed approach with the method that did not account for the perception latency
All-Optical Switching Based on Grating Written Photorefractive Slab/Fiber Waveguide Coupler
(Institute of Electrical and Electronics Engineers Inc., 2002) Dinleyici, Mehmet Salih; Dinleyici, Mehmet Salih; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Since 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.
Citation - WoS: 7
Citation - Scopus: 8
An All-Optical Switching Based on Resonance Breaking With a Transient Grating
(Institute of Electrical and Electronics Engineers Inc., 2010) Akın, Osman; Dinleyici, Mehmet Salih; Dinleyici, Mehmet Salih; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
A new resonance breaking in-fiber switch as an all-optical network component is investigated and presented. A transient grating is applied to break the transverse resonance of the fundamental waveguide mode and the power coupled into the higher order propagating mode is computed using coupled mode theory (CMT). The coupling of the modes with the grating forming beams in the evanescent region of the waveguide is investigated with four wave mixing (FWM). High conversion efficiency is calculated in the case of perfect phase matching at communication wavelength 1550 nm. The conversion efficiency of the proposed structure is considered in terms of third-order nonlinear susceptibility, and the effect of design and tuning parameters are investigated for grating forming geometry and laser beam intensity, respectively.
Citation - WoS: 2
Citation - Scopus: 2
Ampirik Mod Ayrışımı ile Bilişsel Radar Bayes Hedef Takipçisine İşlerlik Kazandırılması
(Institute of Electrical and Electronics Engineers Inc., 2013) Güntürkün, Ulaş; Güntürkün, Ulaş; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Bilişsel radar alıcısının merkez ünitesi niteliğindeki Bayes Hedef Takipçisine (BHT) işlerlik kazandıran Ampirik Mod Ayrışımı (AMA) tekniğine dayalı bir metot sunulmuştur. Tüm Bayes temelli metotlarda olduğu gibi Bayes hedef takipçisinin performansı da ortam hakkında isabetli ön bilginin varlığına önemli ölçüde bağımlıdır. Bu nedenle, BHT’nin gereksinim duyduğu ön bilgiyi sağlamak üzere tasarlanan Radar Ortam Çözümcüsü (ROÇ), bilişsel radar için kritik bir öneme sahiptir. Bu çalışmada sunulan metot, AMA tekniğinin fraktal süreçler için gösterdiği istatistiksel özelliklere dayalı olup, genel ROÇ tasarımını tamamlar niteliktedir. Özel olarak, ham radar verisi, öncelikle AMA yöntemiyle içkin Mod Fonksiyonlarına (IMF) ayrılmıştır. Faz uyumlu bir radarla alınan ve fraktal Gauss niteli˘gine sahip deniz yankısının IMF enerji istatistiklerine dayalı bir “Sıfır Hipotezi” türetilmiştir. Ham radar verisi, bu hipotezin kabul veya reddine bağlı olarak gruplanan IMF’lerin kısmi bir bindirmesi olarak rafine edilmiştir. Böylelikle hedef içeren duruma yönelik olabilirlik fonksiyonu, yalnızca deniz yankısı içeren olabilirlik fonksiyonundan istatistiksel ölçülerle çok daha ayırt edilebilir bir hale getirilmiştir. Sonuç olarak, ortamdan alınan ölçümler BHT’nin kullanımına uygun bir forma dönüştürülmüştür. Metodun performansı, canlı kaydedilmiş McMaster IPIX veri tabanı kullanılarak görsel olarak sergilenmiş ve Kullback–Leibler uzaklığıyla nicelenmiştir.
Ampute Elektromiyografi Sinyallerinin Evrişimli Sinir Ağları Kullanılarak Sınıflandırılması
(IEEE, 2020) Onay, Fatih; Onay, Fatih; Mert, Ahmet; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The classification of EMG signals for the amputees is important to develop a powered-prosthetic that is capable of replacing with lost limbs. The EMG signals collected from residual limbs reduce the classification accuracy due to muscle movements that cannot be realized properly. In this study, classification performance is aimed to be increased by combining CNN with root mean square (RMS) and waveform length (WL) that are used in analysis of EMG signals successfully. The features such as RMS and WL extracted from EMG signals for the classification of six hand movements at the low, medium, and high force levels were applied to CNN input, and classification results were compared with nearest neighbour and linear discriminant analysis.
Analog Realization of the Quantum Derivative Operator
(IEEE, 2017) Savacı, Ferit Acar; Savacı, Ferit Acar; Erdoğan, R. Uğraş; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this paper, quantum derivative operator which is basic to quantum calculus has been implemented as an analog circuit. The proposed circuit realization and the simulations have been also compared with that of the quantum derivative operator implemented in Mathematica.

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