Now showing items 1-20 of 222

    • 3D electron density estimation in the ionosphere 

      Tuna, Hakan; Arıkan, Orhan; Arıkan, F. (IEEE, 2014)
      Ionosphere has ion distribution which is variable in space and time. There have been physical and empirical studies for modeling the ionosphere. International Reference Ionosphere extended to Plasmasphere (IRI-Plas) is the ...
    • Accurate plane-wave excitation in the FDTD method 

      Gürel, Levent; Oğuz, Uğur; Arıkan, Orhan (IEEE, 1997)
      Different techniques are developed to implement plane-wave excitation on the finite-difference time-domain (FDTD) method, such as the initial-condition, the hard-source, and the connecting-condition techniques, for the ...
    • Adaptive filtering approaches for non-Gaussian stable processes 

      Arıkan, Orhan; Belge, Murat; Çetin, A. Enis; Erzin, Engin (IEEE, 1995-05)
      A large class of physical phenomenon observed in practice exhibit non-Gaussian behavior. In this paper, α-stable distributions, which have heavier tails than Gaussian distribution, are considered to model non-Gaussian ...
    • Adaptive filtering for non-gaussian stable processes 

      Arıkan, Orhan; Çetin, A. Enis; Erzin, E. (IEEE, 1994)
      A large class of physical phenomenon observed in practice exhibit non-Gaussian behavior. In this letter, a-stable distributions, which have heavier tails than Gaussian distribution, are considered to model non-Gaussian ...
    • Adaptive measurement matrix design for compressed DoA estimation with sensor arrays 

      Özer, Berk; Lavrenko, A.; Gezici, Sinan; Römer, F.; Galdo, G. D.; Arıkan, Orhan (IEEE, 2015)
      In this work we consider the problem of measurement matrix design for compressed 3-D Direction of Arrival (DoA) estimation using a sensor array with analog combiner. Since generic measurement matrix designs often do not ...
    • Adaptive measurement matrix design in compressed sensing based direction of arrival estimation 

      Kılıç, Berkan; Güngör, Alper; Kalfa, Mert; Arıkan, Orhan (IEEE, 2021)
      Design of measurement matrices is an important aspect of compressed sensing (CS) based direction of arrival (DoA) applications that enables reduction in the analog channels to be processed in sparse target environments. ...
    • Adaptive tracking of narrowband HF channel response 

      Arikan, F.; Arıkan, Orhan (Wiley-Blackwell Publishing, 2003)
      Estimation of channel impulse response constitutes a first step in computation of scattering function, channel equalization, elimination of multipath, and optimum detection and identification of transmitted signals through ...
    • ADMM based mainlobe power constrained phase-only sidelobe supression 

      Alp, Yaşar Kemal; Arıkan, Orhan (IEEE, 2014)
      A novel sidelobe suppression technique is proposed for phased arrays, where only the phases of the array elements are adjusted to suppress the gain in the direction of interest while keeping the mainlobe power at a certain ...
    • Akut koroner sendromların otomatik ST/T sınıflandırıcısı ile erken tanısı 

      Terzi, M. Begüm; Arıkan, Orhan; Abacı, A.; Candemir, M.; Dedoğlu, Mehmet (IEEE, 2014-10)
      In patients with acute coronary syndrome, temporary chest pains together with changes in ECG ST segment and T wave occur shortly before the start of myocardial infarction. In order to diagnose acute coronary syndromes ...
    • Akut koroner sendromun destek vektör makinelerine ve EKG’ye dayalı tespiti 

      Terzi, Merve Begüm; Arıkan, Orhan (IEEE, 2019-04)
      Akut koroner sendroma (AKS) sahip hastalarda, miyokard infarktüsü başlangıcından önce geçici göğüs ağrıları ile birlikte EKG sinyalinin ST segmentinde ve T dalgasında değişiklikler meydana gelmektedir. Bu çalışmada, AKS’nin ...
    • Algorithm for high quality ionograms 

      Arikan, F.; Salous, S.; Arıkan, Orhan (IEEE, 2000)
      A new ionogram algorithm, which is highly successful in generating robust and sharp digital ionograms free of artefacts and processing noise, is presented. An important feature of the algorithm is the distortionless zooming ...
    • Algorithms and basis functions in tomographic reconstruction of ionospheric electron density 

      Yavuz, E.; Arıkan, F.; Arıkan, Orhan; Erol, C. B. (IEEE, 2005)
      Computerized ionospheric tomography (CIT) is a method to investigate ionosphere electron density in two or three dimensions. This method provides a flexible tool for studying ionosphere. Earth based receivers record signals ...
    • AM/FM signal estimation with micro-segmentation and polynomial fit 

      Deprem, Z.; Çetin, A. Enis; Arıkan, Orhan (Springer U K, 2014-03)
      Amplitude and phase estimation of AM/FM signals with parametric polynomial representation require the polynomial orders for phase and amplitude to be known. But in reality, they are not known and have to be estimated. A ...
    • Application of modified particle swarm optimization method for parameter extraction of 2-D TEC mapping 

      Toker, C.; Gökdağ, Y. E.; Arıkan, F.; Arıkan, Orhan (EGU, 2012-04)
      Ionosphere is a very important part of Space Weather. Modeling and monitoring of ionospheric variability is a major part of satellite communication, navigation and positioning systems. Total Electron Content (TEC), which ...
    • Association of ionospheric storms and substorms of global electron content with proxy AE index 

      Yenen, S. D.; Gulyaeva, T. L.; Arikan, F.; Arıkan, Orhan (Pergamon Press, 2015)
      Storm time modeling of Global Electron Content (GEC) calculated from GIM-TEC for 1999-2013 is associated with new proxy of Auroral Electrojet variability expressed as a smoothed and normalized Auroral Electrojet index ...
    • Autofocused sparse SAR image reconstruction by EMMP algorithm 

      Uğur, Salih; Gürbüz, A. C.; Arıkan, Orhan (IEEE, 2012-05)
    • Autofocused spotlight SAR image reconstruction of off-grid sparse scenes 

      Camlıca, S.; Gurbuz, A. C.; Arıkan, Orhan (Institute of Electrical and Electronics Engineers Inc., 2017)
      Synthetic aperture radar (SAR) has significant role in remote sensing. Phase errors due to uncompensated platform motion, measurement model mismatch, and measurement noise can cause degradations in SAR image reconstruction. ...
    • “Backward differential flow” may not converge to a global minimizer of polynomials 

      Arıkan, Orhan; Burachik, R. S.; Kaya, C. Y. (Springer New York LLC, 2015)
      We provide a simple counter-example to prove and illustrate that the backward differential flow approach, proposed by Zhu, Zhao and Liu for finding a global minimizer of coercive even-degree polynomials, can converge to a ...
    • Bandwidth selection for kernel density estimation using fourier domain constraints 

      Suhre, A.; Arıkan, Orhan; Çetin, A. Enis (Institution of Engineering and Technology, 2016)
      Kernel density estimation (KDE) is widely-used for non-parametric estimation of an underlying density from data. The performance of KDE is mainly dependent on the bandwidth parameter of the kernel. This study presents an ...
    • A Bayesian approach to respiration rate estimation via pulse-based ultra-wideband signals 

      Soǧancı, Hamza; Gezici, Sinan; Arıkan, Orhan (IEEE, 2009)
      In this paper, theoretical limits on estimation of respiration rates via pulse-based ultra-wideband (UWB) signals are studied in the presence of prior information about respiration related signal parameters. First, a ...