Scopus İndeksli Yayınlar Koleksiyonu
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Browsing Scopus İndeksli Yayınlar Koleksiyonu by Language "tr"
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Conference Object Citation Count: 0Alternative transducer power gain expression in broadband matching network designs(Institute of Electrical and Electronics Engineers Inc., 2017) Sengul, M.In this paper, a reflection coefficient based transducer power gain expression has been derived, which is an alternative to the impedance based expression exists in the literature. A broadband double matching problem is solved by using the derived gain expression and the obtained performance has been compared with the performance obtained via the existing expression. © 2016 The Chamber of Turkish Electrical Engineers.Conference Object Citation Count: 1An analysis for the use of compressed sensing method in microwave imaging [Mikrodalga Görüntülemede Sıkıştırılmış Algılama Yönteminin Kullanımına Yönelik Bir Analiz](Institute of Electrical and Electronics Engineers Inc., 2017) Yiğit, Enes; Tekbaş, Mustafa; Ünal, İlhami; Erdogan, Sercan; Çalışkan, CaferOne of the most important problems encountered in microwave imaging methods is intensive data processing traffic that occurs when high resolution and real time tracking is desired. Radar signals can be recovered without loss of data with a randomly selected subset of the measurement data by compression sensing (CS) method which has been popular in recent years. For this reason in this study the use and capabilities of the CS method were investigated for tracking moving human and the target information was correctly determined for the data obtained much below the Nyquist sampling criterion. In this study it was revealed that the CS method can be developed for target detection and tracking. © 2017 IEEE.Conference Object Citation Count: 1Analysis of deep learning based path loss prediction from satellite images(IEEE, 2021) Baykaş, Tunçer; Ates, Hasan F.; Baykas, Tuncer; Gunturk, Bahadir K.Determining the channel model parameters of a wireless communication system, either by measurements or by running electromagnetic propagation simulations, is a time-consuming process. Any rapid deployment of network demands faster determination of at least major channel parameters. In this paper, we investigate the idea of using deep convolutional neural networks and satellite images for channel parameters (i.e., path loss exponent n and shadowing factor sigma) prediction in a cellular network with aerial base stations. Specifically, we investigate the performance dependency of the method on three different factors: height of the transmitter antenna, quantization levels of the channel parameters and architectural design of CNN. The results presented in this paper show a high prediction accuracy of the channel parameters in real-time.Conference Object Citation Count: 2Analytical approaches for the amplitude and frequency computations in the astable cellular neural networks with opposite sign templates(2007) Tander, B.; Özmen, A.In this paper, by using surface fitting methods, analytical approaches for amplitudes and frequencies of the x1,2(t) "States" in a simple dynamical neural network called "Cellular Neural Network with Opposite Sign Templates" which was proposed by Zou and Nossek [1], are obtained under oscillation conditions. The mentioned explicit expressions are employed in a cellular neural network based, amplitude and frequency tuneable oscillator design.Conference Object Citation Count: 15Android Malware Detection Using Machine Learning(Institute of Electrical and Electronics Engineers Inc., 2020) Tahtaci, B.; Canbay, B.The usage of mobile devices is increasing exponentially. There were lots of critical applications such as banking to health applications are available on mobile devices through mobile applications. This penetration and spread of mobile applications brings some threats. Malicious software(Malware) is one of these dangers. Malware has the potential to cause damage to various scales such as theft of sensitive data, identity and credit card. To reduce the effects of these threats, antiviruses have been developed and malware analysis teams have been established, but human effort may be insufficient in the rapidly growing malware market. For this reason, automated malware scanning solutions should be developed by making use of machine learning algorithms. In this study, machine learning models were created by using the n-gram features of the smali files, which are the decompiled Android packages. The trained models are combined with different feature extraction and feature selection methods and as a result their performances are reported. © 2020 IEEE.Conference Object Citation Count: 2Anomaly detection in walking trajectory [Yürüyüş yörüngesinde anormallik algılama](Institute of Electrical and Electronics Engineers Inc., 2018) Öğrenci, Arif SelçukAnalysis of the walking trajectory and the detection of anomalies in this trajectory provide important benefits in the fields of health and security. In this work two methods to detect anomalies in trajectories are compared. Firstly an unsupervised method is used where the conformance among trajectories are taken into consideration. Trajectories that deviate from others are qualified as anomalies. Secondly the points in the trajectories are considered as a time series. Artifical neural networks performing supervised learning based on the backpropagation algorithm are used. The results are compared and the points to be enhanced are highlighted.Article Citation Count: 0Assesment of soft error sensitivity of power flow analysis(Gazi Univ, Fac Engineering Architecture, 2023) Yetkin, Emrullah FatihToday's power systems are large and interconnected to each other with many buses, lines, loads, and generators. Even the solution of a single snapshot of the system for specific conditions requires the solution of systems of equations with large sizes. Thus, to obtain the results in a reasonable time for large problems like electrical power flow simulations, modern large computational environments should be employed. However, because of the increasing number of components in the modern computational environment, the possibility of soft errors also increases. Soft errors can be defined as failures arising from several fluctuations due to x-rays, cosmic particle effects, etc. These types of errors usually appear at any time of computation as a bit-flip in any floating-point operations. In this paper, we will investigate the soft-error effects on large-scale power flow simulations. Generally, power flow calculations are performed by using Newton Raphson Method. The system is modeled by nonlinear equations and the solution process requires a linear solver is employed to take the inverse of the Jacobian matrix at each iteration. In this study, the soft-error sensitivity of the numerical methods used in load flow was examined, and the problems that may be encountered were revealed.Article Citation Count: 0Broadband Matching via Reflection Coefficient Modeling(AVES YAYINCILIK, 2016) Şengül, Metin Y.[Abstract Not Available]Conference Object Citation Count: 1Busy tone based power control for coordination of IEEE 802.11af and 802.22 system [IEEE 802.11af ve 802.22 Sistemlerinin Uyumlu Çalışmaları için Meşgul Ton Tabanlı Güç Kontrolü](Institute of Electrical and Electronics Engineers Inc., 2017) Baykaş, Tunçer; Erküçük, Serhat; Karatalay, Onur; Baykaş, TunçerIn this paper a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies in addition to both 802.11af access point and clients listening to the busy tone they also adjust their communication power according to the location information and use hopping for communication if needed. Acccordingly interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards. © 2017 IEEE.Conference Object Citation Count: 2Busy tone implementation for coexistence of IEEE 802.22 and 802.11af systems(Institute of Electrical and Electronics Engineers Inc., 2015) Baykaş, Tunçer; Erküçük, S.; Baykaş, T.In this paper, a new algorithm based on busy tone approach has been proposed for the coexistence of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier study, in addition to 802.11af access points listening to the busy tone signal, their clients also listen to the busy tone and let the access points know once they hear it. Accordingly, interference caused to 802.22 systems has been reduced. This study quantifies the improved system performance in terms of interfering packet rate for different hearing regions considering the communication parameters and channel models adapted for the standards. © 2015 IEEE.Review Citation Count: 1Cervical spine injuries in children(2004) Hamzaoglu, A.; Mirzanli, C.Cervical spine injuries in children and adolescents are rare. Common mechanisms include motor vehicle accidents, sports injuries, fall from height, and gunshot injuries. Cervical spine injuries are classified by Allen and Ferguson according to the period they occur, as infantile, early juvenile, and late juvenile. Anatomically, two main types are defined as occipitoatlantal (upper cervical) and subaxial injuries. The purpose of this paper is to review cervical spine injuries in children and adolescents with respect to epidemiology, injury mechanisms, diagnosis, clinical and radiologic aspects, and treatment in the light of the current literature.Conference Object Citation Count: 3Channel Estimation for DCO-OFDM Based VLC Systems in the Presence of Clipping Noise(Institute of Electrical and Electronics Engineers Inc., 2020) Bektas, E.B.; Panayırcı, ErdalVisible Light Communication(VLC) has been considered as a potential access option for 6G wireless systems to solve performance limitation due to bandwidth shortage at radio frequency (RF) band. In VLC system, illumination infrastructure has dual usage at the same time namely illumination and wireless data transmission. DC-Biased optical DCO-OFDM with clipping has been proposed for VLC systems to provide optically power efficient solution and easy implementation. Wireless communication systems generally require estimating and tracking the fading channel in order to detect transmitted data coherently. In this work, we propose a pilot-aided iterative channel estimation algorithm to efficiently estimate the optical channel coefficients of a clipped DCOOFDM system operating with additive white Gaussian noise (AWGN). The estimation algorithm is capable of improving the channel estimation by making use of pilot symbols with interpolation or using the channel estimate of previous OFDM block to obtain the next estimate for the iterative algorithm. In each iteration, the clipping noise is estimated and compensated in the frequency domain. Simulation results verify that the proposed channel estimation algorithm reduces the bit error rate (BER) and mean-square error (MSE) of channel estimate can be significantly. © 2020 IEEE.Conference Object Citation Count: 2Channel Estimation Using Optical MIMO OFDM Based LED Index Modulation(IEEE, 2021) Okumus, Furkan Batuhan; Panayırcı, ErdalIn this paper, a new MIMO channel estimation technique is proposed for generalized LED index modulation (GLIM-OFDM) developed for multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) based VLC systems. The mean square error (MSE) of the channel estimation algorithm, the bit error rate (BER) and the Cramer-Rao (CR) lower-bound of the system were obtained analytically and the performance of the algorithm according to the signal-to-noise ratio was investigated by computer simulations. From the obtained MSE, BER and CR curves it is concluded that the MSE performance of the proposed channel estimation algorithm is very high and the BER performance of the system obtained with the estimated channel information is very close to the BER performance in the case of perfect knowledge of the channel.Conference Object Citation Count: 5Comparison of Compressed Sensing Based Algorithms for Sparse Signal Reconstruction(IEEE, 2016) Çelik, Safa; Başaran, Mehmet; Erküçük, Serhat; Çırpan, Hakan AliCompressed sensing theory shows that any signal which is defined as sparse in a given domain can be reconstructed using fewer linear projections instead of using all Nyquist-rate samples. In this paper we investigate basis pursuit matching pursuit orthogonal matching pursuit and compressive sampling matching pursuit algorithms which are basic compressed sensing based algorithms and present performance curves in terms of mean squared error for various parameters including signal-tonoise ratio sparsity and number of measurements with regard to mean squared error. In addition accuracy of estimation performances has been supported with theoretical lower bounds (Cramer-Rao lower bound and deterministic lower mean squared error). Considering estimation performances compressive sampling matching pursuit yields the best results unless the signal has a non-sparse structure.Article Citation Count: 5Coronary bypass surgery in octogenarians(2001) Arbatli, H.; Unal, M.; Demirsoy, E.; Tansal, S.; Yagan, N.; Tükenmez, F.; Sener, D.OBJECTIVE: The age of the patients referred for coronary bypass surgery is getting older progressively. Early and late postoperative outcome of octogenarians were evaluated and compared with younger age group in this study. METHODS: Records of 55 patients aged 80 years or older (mean age 82.7 +/- 2.8) among 3834 patients, who had coronary bypass graft procedure, operated between 1995 and 2001 were reviewed retrospectively. RESULTS: There were 39 men (70.9%) and 16 women (29.1%). Three patients had aortic valve replacement, 1 had left ventricular aneurysm repair, 1 had carotid endarterectomy additionally. Atrial fibrillation (21.8%), renal dysfunction (16.4%), and prolonged ventilation (10.9%) were the prominent complications. The hospital mortality rate was 7.27% (4 patients). Kaplan Meier Survival Analysis estimated that at the end of 5 years 83.1 + 5.2% of patients were still alive. CONCLUSION: Coronary bypass operations can be performed in octogenarians with slightly increased but acceptable hospital mortality and longer hospital stay. Early intervention and individual modifications in cardiopulmonary bypass techniques may improve the results in this patient population.Article Citation Count: 0Development of an enzyme immunoassay for the determination of testosterone(2003) Güven, B.; Özsar, S.; Maraşli, N.; Maraşli, Ş.; Özcan, A.In this study, a double antibody enzyme immunoassay for the direct determination of testosterone in plasma was developed. Testosterone 3-O-CMO was conjugated with horseradish peroxidase by the mixed anhydride method, and the conjugate purified by column chromatography (sephadex G-25). Testosterone antibody was obtained by immunization of rabbits against Testosterone-3-O-CMO-BSA. Cross reactions of the antiserum against some steroids were found to be <0.01%. The detection limit of the assay was 2.5 pg/well and the working range of the standard curve was 0-20 ng/ml (0-200 pg/well). The recovery was found to be 98.8% after the addition of known amounts of testosterone to plasma samples. The inter-assay coefficient of variation was 12.6%. The described EIA offers a very economical alternative for the routine estimation of testosterone levels. Only minimal laboratory equipment is required and therefore the assay should be especially useful for research in animal science.Article Citation Count: 4The education of international relations in turkey and orientalism: A critical pedagogical approach to the discipline(International Relations Council of Turkey, 2019) Ongur, H.Ö.; Gürbüz, S.E.Using a qualitative discourse analysis, this article aims at introducing the sub-discipline of Critical Pedagogy (CP) to the studies of International Relations (IR), incorporating the orientalist text analysis into CP and arguing over the orientalist texture of the undergraduate education of IR in Turkey. It is argued here that due to the Western-centrism of CP studies, they ‘forget’ to bring into question the orientalist tone of the standardized Western curricula, next to the main discussions of academic capitalism and neoliberal instrumentalization of education. Making an investigation of the curricula and the fundamental reading materials over ten selected IR programmes in Turkey, this article both recalls this need of orientalist inquiry in CP studies and provides a fresh perspective for the scholarly analysis of the IR education in Turkey. The findings suggest a non-critical reproduction of the Western literature for the Turkish IR as well as a continuation, if not reinforcement, of this literature by the Turkish-speaking academia. As a result, it is argued here that the orientalist subtext of concepts, including radical Islam, Jihadism, fundamentalism, Islamic terror, the Third World, underdevelopment, etc., has become a part of the IR literature in Turkey. © 2019, International Relations Council of Turkey. All rights reserved.Conference Object Citation Count: 0Effect of channel estimation errors on the performance of space time coded systems with antenna selection(2007) Güçlüoğlu, T.; Panayırcı, ErdalThis paper presents the effects of channel estimation errors on the performance, especially diversity gain, of space-time coded systems with antenna selection. We consider maximum signal to noise ratio as the antenna selection criteria. Specifically, we first present the effect on the upper bound for pairwise error probability of space-time coded systems with antenna selection over flat fading channels. Moreover, we provide simulation results for the antenna selection at the receiver and/or transmitter to show the effect of channel estimation.Conference Object Citation Count: 1The effect of channel resolution on compressed sensing based Ultra-Wideband channel estimation [Kanal çözünürlü?ünün sıkıştırılmış algılama tabanlı ultra geni?ş bantlı kanal kesti?ri?mi?ne etki?si?](2011) Başaran, Mehmet; Erküçük, Serhat; Cirpan, Hakan AliUltra short pulses are transmitted in Ultra-Wideband (UWB) communications. As a result of this pulses at the receiver can be resolved individually due to the sparse structure of the channel. Due to these properties the UWB channel can be estimated by using a compressed sensing based channel estimation method. The performance of channel estimation depends on the sparsity of the channel. In this work the effect of channel resolution which directly affects the sparsity is examined. It is shown that the channel becomes more sparse and the channel estimation performance is improved with increased channel resolution. Also the system performances of practically used selective-Rake receivers with estimated channels are found to be close to the perfect channel estimation case. © 2011 IEEE.Conference Object Citation Count: 1The Effect of Codebook Design on the Conventional SCMA System Performance(Institute of Electrical and Electronics Engineers Inc., 2020) Şadi, Yalçın; Bardakci, E.; Sadi, Y.; Erkucuk, S.In 4G systems, Orthogonal Frequency-Division Multiple Access (OFDMA) has been used conventionally for multiple access purposes. This technique has low spectral efficiency since it allocates the resources orthogonally to each user. As an alternative to this technique, Non-orthogonal Multiple Access (NOMA) has been proposed for new generation systems as it allows different users to use the same resources and therefore, increases spectral efficiency. Sparse Code Multiple Access (SCMA) is a code-based NOMA technique and its performance depends on codebook design. In this study, a conventionally used codebook design in the literature has been considered and the system performance has been improved by increasing the distance between the signal constellation points. Considering two different design approaches, the conventional codebook has been modified and about 1dB gain has been achieved in the high signal-to-noiseratio (SNR) region. © 2020 IEEE.