Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://gcris.khas.edu.tr/handle/20.500.12469/1248

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Citation Count: 0
Alternative 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.
Citation Count: 1
An 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) Çalışkan, Cafer; Tekbaş, Mustafa; Ünal, İlhami; Erdogan, Sercan; Çalışkan, Cafer
One 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.
Citation Count: 1
Analysis 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.
Citation Count: 10
An analysis of international relations academics in Turkey and their approaches to the field: TRIP 2014 faculty survey results;
(International Relations Council of Turkey, 2016) Aydın, Mustafa; Hisarlioğlu,F.; Yazgan,K.
Despite the increasing interest in the studies inquiring the limits, autonomous character of and the interactions between the International Relations (IR) discipline and other academic fields, the scope and scale of empirical research on these issues are relatively small. In order to contribute to the discussion on the limits and peculiarities of the IR discipline and to shed light on the development, current status and major characteristics of the IR studies in Turkey, its place in the global IR discipline and the views of IR scholars on major issues on the global, regional and national agenda, two surveys were conducted by the International Relations Council of Turkey (IRCT) in 2007 and 2009. Later on, the IRTC collaborated with the Institute for the Theory and Practice of International Relations at the College of William and Mary to conduct further surveys in 2011 and 2014. This paper presents findings of the last survey on Turkey, based on the worldwide research simultaneously conducted in 31 different countries in September 2014. © 2016, International Relations Council of Turkey. All rights reserved.
Citation Count: 2
Analytical approaches for the amplitude and frequency computations in the astable cellular neural networks with opposite sign templates
(2007) Özmen, Atilla; 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.
Citation Count: 15
Android 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.
Citation Count: 2
Anomaly detection in walking trajectory [Yürüyüş yörüngesinde anormallik algılama]
(Institute of Electrical and Electronics Engineers Inc., 2018) Öğrenci, Arif Selçuk
Analysis 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.
Citation Count: 0
Assesment of soft error sensitivity of power flow analysis
(Gazi Univ, Fac Engineering Architecture, 2023) Yetkin, Emrullah Fatih; Yetkin, Emrullah Fatih
Today'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.
Citation Count: 0
Atmosferik Türbülans Altinda Orbital Açisal Momentum Tabanli Haberleşme Sistemleri Orbital Angular Momentum Based Communication Systems under Atmospheric Turbulence;
(Institute of Electrical and Electronics Engineers Inc., 2020) Sheikh,A.A.A.; Basaran,M.; Erkucuk,S.
Orbital Angular Momentum (OAM) may be a candidate for future communication systems due to its advantages in terms of high data rates and effective frequency utilization. OAM can provide a solution where a beam is transformed into multiple beams within itself and becomes independent streams of data (pertaining to the principle of orthogonality) to be transferred when properly utilized. However, the free space contains atmospheric turbulence which interferes with the beam propagation of OAM and as a result the photons in the light beam are affected as well as the independence of each OAM mode. Therefore, the data stream suffers crosstalk. In this study, weak and strong atmospheric turbulences and how they affect a variety of OAM modes as they propagate through free space are investigated, and important OAM implementation issues are discussed. © 2020 IEEE.
Citation Count: 0
Broadband Matching via Reflection Coefficient Modeling
(AVES YAYINCILIK, 2016) Şengül, Metin
[Abstract Not Available]
Citation Count: 1
Busy 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, Tunçer
In 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.
Citation Count: 2
Busy tone implementation for coexistence of IEEE 802.22 and 802.11af systems
(Institute of Electrical and Electronics Engineers Inc., 2015) Baykaş, Tunçer; Erküçük, Serhat; 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.
Citation Count: 1
Cervical 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.
Citation Count: 3
Channel Estimation for DCO-OFDM Based VLC Systems in the Presence of Clipping Noise
(Institute of Electrical and Electronics Engineers Inc., 2020) Panayırcı, Erdal; Panayırcı, Erdal
Visible 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.
Citation Count: 2
Channel Estimation Using Optical MIMO OFDM Based LED Index Modulation
(IEEE, 2021) Panayırcı, Erdal; Panayırcı, Erdal
In 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.
Citation Count: 5
Comparison of Compressed Sensing Based Algorithms for Sparse Signal Reconstruction
(IEEE, 2016) Erküçük, Serhat; Başaran, Mehmet; Erküçük, Serhat; Çırpan, Hakan Ali
Compressed 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.
Citation Count: 5
Coronary 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.
Citation Count: 0
The Decision of the Turkish Constitutional Court on the Peace Petition: An Analysis in the Context of Freedom of Expression, Academic Freedom and the Concept of Loyalty to the State;
(Turkish Medical Association, 2020) Ergün,R.; Özenç,B.
In this paper, Turkish Constitutional Court’s decision on the individual application of Zübeyde Füsun Üstel and Others, which is an important turning point in the legal struggle of the signatories of the petition titled “We will not be a party to this crime”, is examined in the context of freedom of expression, academic freedom and the concept of loyalty to the state. Within this framework, firstly, the jurisprudence of the European Court of Human Rights and the Turkish Constitutional Court regarding freedom of expression were summarized and the method of exa-mination used by the Constitutional Court in Zübeyde Füsun Üstel and Others case was discussed. Secondly, due to the close relationship of the case of Academics for Peace with academic freedom, the discussions on academic freedom within international human rights mechanisms, especially in the jurisprudence of the European Court of Human Rights was examined in detail, and it was argued that the Constitutional Court developed a new jurisprudence in this context. Thirdly, the dissenting opinions on the case were analyzed with a special focus on the concept of loyalty to the state used by the judges dissenting from the decision of the majority as an indicator of their mindset. The analysis concluded that the dissenting judges regarded themselves rather as protectors of the interests of the state than as the guardians of the rule of law and human rights. The discussions on the judicial independence and impartiality in Turkey were also taken into consideration for the analysis. © 2020, Turkish Medical Association. All rights reserved.
Citation Count: 0
Development 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.
Citation Count: 0
Distinguishing Cognitive Processes: A Machine Learning Approach to Decode fNIRS Data for Third-Party Punishment and Credit Decision-Making;
(Institute of Electrical and Electronics Engineers Inc., 2024) Filiz,G.; Son,S.; Sayar,A.; Ertuğrul,S.; Şahin,T.; Akyürek,G.; Çakar,T.
Functional near-infrared spectroscopy (fNIRS) has seen increasingly widespread use in examining brain activity and cognitive processes. However, the existing literature provides insufficient information on distinguishing between different decision-making mechanisms. This study explores the application of fNIRS in differentiating between two distinct decision-making processes: third-party punishment decisions and credit decisions. The research includes analyzing fNIRS data collected during these processes and classifying the associated neural patterns using machine learning. The findings reveal that fNIRS, in conjunction with ML, holds substantial potential to enhance the depth of understanding of decision-making processes in neuroscience research. © 2024 IEEE.

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