Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
10 results
Search Results
Now showing 1 - 10 of 10
Article Citation - WoS: 4Citation - Scopus: 4Electromagnetic Simulations of Mechanical Imperfections for Accelerator Cavities(Institute of Electrical and Electronics Engineers Inc., 2019) Karatay, Anıl; Yaman, FatihEffects of surface roughness and transversal cell misalignments on the performance of elliptical accelerator cavities are studied in this article. A high-beta, 9-cell elliptical cavity, whose pi-mode resonates at 3.9 GHz, is designed to investigate imperfections. The considered frequency is chosen to observe variations of fundamental accelerating cavity parameters, wake potentials, and wake impedances more clearly by using relatively small structures. Moreover, 3-cell elliptical cavities having pi-mode at 2 and 3.9 GHz are designed to confirm the 9-cell cavity results. The undesired effects caused by the considered mechanical imperfections are simulated for an ultra-relativistic bunch in the parameter scope of a realistic scenario. In particular, Huray's snowball model, which is a scattering-based surface roughness approach developed for microstrip lines, is employed to determine the effects of the surface roughness on the accelerator cavities. Surface roughness due to the fabrication process is expressed as a surface impedance, and the required equivalence between the surface roughness and surface impedance concept is achieved. Significant computational efficiency is observed by using the surface impedance concept with Huray's snowball model in the simulations. Experimental verification of certain parameters is included for an elliptical cavity having high cell-to-cell coupling at 3.9 GHz.Article Citation - WoS: 3Citation - Scopus: 4Hierarchical Motif Vectors for Prediction of Functional Sites in Amino Acid Sequences Using Quasi-Supervised Learning(Institute of Electrical and Electronics Engineers Inc., 2012) Karaçalı, BilgeWe propose hierarchical motif vectors to represent local amino acid sequence configurations for predicting the functional attributes of amino acid sites on a global scale in a quasi-supervised learning framework. The motif vectors are constructed via wavelet decomposition on the variations of physico-chemical amino acid properties along the sequences. We then formulate a prediction scheme for the functional attributes of amino acid sites in terms of the respective motif vectors using the quasi-supervised learning algorithm that carries out predictions for all sites in consideration using only the experimentally verified sites. We have carried out comparative performance evaluation of the proposed method on the prediction of N-glycosylation of 55,184 sites possessing the consensus N-glycosylation sequon identified over 15,104 human proteins, out of which only 1,939 were experimentally verified N-glycosylation sites. In the experiments, the proposed method achieved better predictive performance than the alternative strategies from the literature. In addition, the predicted N-glycosylation sites showed good agreement with existing potential annotations, while the novel predictions belonged to proteins known to be modified by glycosylation.Article Citation - WoS: 7Citation - Scopus: 10Design and Implementation of a Tem Stripline for Emc Testing(Institute of Electrical and Electronics Engineers Inc., 2014) Hilavin, Sezgin; Kuştepeli, AlpIn this paper, a stripline for radiated field immunity testing of audio/video products is designed, constructed, calibrated, and verified. Since the canonical one is only suitable for testing equipments with height less than 70 cm, there is a need of a new device which is also in compliance with EN 55020 standard for testing new large sets, like 47″ thin-film transistor liquid crystal display (TFT LCD) television sets, in the frequency range of 150 kHz-150 MHz. Increasing the height and width of testing area causes important problems in terms of field uniformity regarding the higher order modes, characteristic impedance, and reflections in addition to the room resonances and field interference sources like corners at the edges of stripline. Comprehensive numerical study is performed to overcome these problems and obtain the optimum design before the construction. Measured data show that the new stripline is in very good agreement with the specifications determined by the standards and therefore it can be used for the electromagnetic compatibility (EMC) testing.Conference Object Citation - WoS: 5Citation - Scopus: 3Hierarchical Successive Stream Selection for Heterogeneous Network Interference(Institute of Electrical and Electronics Engineers Inc., 2014) Aycan, Esra; Özbek, Berna; Le Ruyet, DidierThis paper presents a hierarchical stream selection approach to deal with the interference in a heterogeneous network where different cell types are coexisting with each other to increase the sum capacity. Due to the variety of the transmit powers between the macro and small cells, interference levels are different. The proposed solution hierarchically selects the strongest streams of each cell with a contribution to the sum rate, while constructing the streams via singular value decomposition (SVD). In order to reduce the interference, the channel matrices of the remaining streams are projected orthogonally to the virtual transmit channel and virtual receive channel of the selected stream. The performance evaluations are obtained by considering different locations of small cells with respect to the macro cell. It is shown that the proposed method can dynamically select more streams in heterogeneous networks and achieve higher data rates compared to the existing algorithms. © 2014 IEEE.Conference Object Citation - WoS: 3Citation - Scopus: 6Online Time Delay Identification and Control for General Classes of Nonlinear Systems(Institute of Electrical and Electronics Engineers Inc., 2012) Bayrak, Alper; Tatlıcıoğlu, EnverIn this study, online identification of state delays is discussed. First, a novel adaptive time delay identification technique is proposed for general classes of autonomous nonlinear systems subject to state delays. As an extension, this technique is modified to design a tracking controller for general classes of nonlinear systems subject to state delays. The main novelty of this controller is that identification of unknown state delays is ensured while output tracking objective is satisfied. Extensive numerical simulations are presented that demonstrate the efficiency of the time delay identification algorithm and the tracking controller. © 2012 IEEE.Conference Object Citation - Scopus: 2Fairness Aware Resource Allocation for Downlink Miso-Ofdma Systems(Institute of Electrical and Electronics Engineers Inc., 2012) Baştürk, İlhan; Özbek, BernaIn this paper, a resource allocation problem for downlink multiple input-single output orthogonal frequency division multiple access (MISO-OFDMA) systems is investigated. The problem is defined as maximizing the minimum user rate with the constraints of total power and bit error rate (BER). Since it is difficult to obtain the optimal solution to this problem, a suboptimal but efficient solution is proposed based on zero forcing beamforming (ZFBF) to reduce computational complexity. The proposed algorithm is a fairness aware radio resource allocation algorithm that shares the resources equally among the users who has different distances from the Base Station (BS). The simulation results show that the proposed algorithm satisfies the fairness criterion having higher data rates compared to the existing algorithms. © 2012 IEEE.Article Citation - WoS: 2Citation - Scopus: 2The Groove-Guide Oscillator(Institute of Electrical and Electronics Engineers Inc., 2011) Bechteler, Thomas F.; Aydınlık Bechteler, Ayşe SevinçThe groove guide, a low-loss waveguide consists of two separate parallel plates whose separation distance can be adjusted, thereby affecting the frequency of operation of the guide itself. The standing waves in a groove guide along the direction of propagation are commonly obtained by either total reflection at both ends or by forming a closed loop. A negative resistance has to be implemented to induce oscillations of the groove guide resonator. It is desirable to induce oscillations directly inside the groove region therefore the negative resistance must be placed inside the groove. A Gunn element was selected to provide this negative resistance. A standard heterodyne system may be realized in order to use the groove-guide oscillator for distance or permittivity measurements. The groove-guide oscillator works as an active sensor in the X-band. The accuracy with which the resonant frequency is determined depends on the bias stability of the Gunn element, the phase noise of the local oscillator, and the error of the frequency counter.Conference Object Citation - WoS: 1Citation - Scopus: 3Iterative Em-Based Channel Estimation for Stbc-Ofdm(Institute of Electrical and Electronics Engineers Inc., 2009) Baştürk, İlhan; Özbek, BernaIn this paper, an iterative EM based channel estimation algorithm is studied for STBC-OFDM systems. Compared to the time domain EM based channel estimation algorithm which needs matrix inversion, a frequency domain EM based channel estimation algorithm is proposed by estimating the channel coefficients for each subcarrier. The proposed channel estimation algorithm decreased the complexity without sacrificing the performance. The time domain and proposed frequency domain EM based channel estimation algorithms are compared in terms of bit error rate (BER), mean square error (MSE) and the number of iterations used in the EM algorithm.Conference Object Citation - Scopus: 9Event-Based Input Validation Using Design-By Patterns(Institute of Electrical and Electronics Engineers Inc., 2009) Tuğlular, Tuğkan; Müftüoğlu, Can Arda; Belli, Fevzi; Linschulte, M.This paper proposes an approach for validation of numerical inputs based on graphical user interfaces (GUI) that are modeled and specified by event sequence graphs (ESG). For considering complex structures of input data, ESGs are augmented by decision tables and patterns of design by contract (DbC). The approach is evaluated by experiments on boundary overflows, which occur when input values violate the range of specified values. Furthermore, a tool is presented that implements our approach enabling a semiautomatically detection of boundary overflow errors and suggesting correction steps based on DbC.Conference Object Citation - WoS: 5Citation - Scopus: 8Teleoperation With Kinematically Redundant Robot Manipulators With Sub-Task Objectives(Institute of Electrical and Electronics Engineers Inc., 2008) Nath, Nitendra; Tatlıcıoğlu, Enver; Dawson, Darren M.In this paper, control of nonlinear teleoperator systems where both the master and slave systems are kinematically redundant robot manipulators is addressed. The controller is developed under the assumption that the user and environmental input forces are unmeasurable. Lyapunovbased stability analysis is used to prove that the proposed controller yields asymptotic tracking results and ensures the coordination of the master and slave systems while satisfying a sub-task objective.