Recent Submissions

  • Active metamaterial nearly perfect light absorbers: A review [Invited] 

    Hajian, Hodjat; Ghobadi, Amir; Bütün, Bayram; Özbay, Ekmel (Optical Society of America, 2019-08)
    Achieving nearly perfect light absorption from the microwave to optical region utilizing metamaterials has begun to play a significant role in photonics and optoelectronics due to their vital applications in thermal emitters, ...
  • Response of porcine articular cartilage to irradiation by an ultrafast, burst-mode laser 

    Dzelzainis, T.; Hammouti, S.; Prickaerts, M.; Cassidy, K.; İlday, F. Ömer; Kalaycıoğlu, H.; Yavaş, S.; Karamuk, Ş.; Golaraei, A.; Barzda, V.; Akens, M.; Lilge, L.; Marjoribanks, R. (Optical Society of America, 2019)
    Plasma-mediated ablation by ultrafast pulses is generally considered to be a material-independent process. We show that, in certain circumstances, this assumption may be invalid. Physical processes involved and the impact ...
  • 94.8 km-range direct detection fiber optic distributed acoustic sensor 

    Uyar, Faruk; Uyar, Talha; Ünal, Canberk; Kartaloğlu, Tolga; Özdur, İbrahim; Özbay, Ekmel (Optical Society of America, 2019)
    This work demonstrates an ultra-long range direct detection fiber optic distributed acoustic sensor which can detect vibrations at a distance of 94.8 km with 10 m resolution along the sensing fiber.
  • Breaking crosstalk limits to dynamic holography using orthogonality of high-dimensional random vectors 

    Makey, Ghaith; Yavuz, Özgün; Kesim, Denizhan K.; Turnalı, Ahmet; Elahi, Parviz; İlday, Serim; Tokel, Onur; İlday, F. Ömer (Nature Publishing Group, 2019)
    Holography is the most promising route to true-to-life three-dimensional (3D) projections, but the incorporation of complex images with full depth control remains elusive. Digitally synthesized holograms1,2,3,4,5,6,7, which ...
  • Corrigendum: Enhancement of polycrystalline silicon solar cells efficiency using indium nitride particles 

    Alkış, Sabri; Chowdhury, F. I.; Alevli, M.; Dietz, N.; Aktürk, S.; Nayfeh, A.; Okyay, Ali Kemal (IOP, 2019)
    In this work, we present a hybrid indium nitride particle/polycrystalline silicon solar cell based on 230 nm size indium nitride particles (InN-Ps) obtained through laser ablation. The solar cell performance measurements ...
  • Fully automated gridding reconstruction for non-Cartesian x-space magnetic particle imaging 

    Özaslan, Ali Alper; Alacaoğlu, Ahmet; Demirel, Ömer Burak; Çukur, Tolga; Sarıtaş, Emine Ülkü (IOP, 2019)
    Magnetic particle imaging (MPI) is a fast emerging biomedical imaging modality that exploits the nonlinear response of superparamagnetic iron oxide (SPIO) nanoparticles to image their spatial distribution. Previously, ...
  • A high gain and high efficiency 15 W X-Band GaN power amplifier MMIC 

    Gürdal, Armağan; Özipek, Ulaş; Sütbaş, Batuhan; Özbay, Ekmel (IEEE, 2019)
    An X-band microstrip power amplifier MMIC based on our 0.25 μm AlGaN/GaN on SiC process technology is presented in this work. Fabrication steps, HEMT structure and typical device performance are demonstrated. Design procedure ...
  • A 6-18 GHz GaN power amplifier MMIC with high gain and high output power density 

    Sütbaş, Batuhan; Özipek, Ulaş; Gürdal, A.; Özbay, Ekmel (IEEE, 2019)
    A three-stage reactively-matched 6-18 GHz power amplifier MMIC design is presented. The design effort is focused on obtaining a low-loss output matching network for a high output power density. Active unit cells consist ...
  • GaN-on-SiC LNA for UHF and L-Band 

    Zafar, Salahuddin; Osmanoğlu, Sinan; Çankaya, Büşra; Kashif, A.; Özbay, Ekmel (IEEE, 2019)
    In this paper, we report a broadband GaN HEMT LNA from 100 MHz to 2 GHz, using common source with inductive degeneration and RC feedback topology. Flat gain response of ±1.5 dB variation for 9 V drain voltage with 108 mA ...
  • An S-Band high gain AlGaN/GaN HEMT MMIC low noise amplifier 

    Muhittin, Tasçı; Şen, Ö.; Özbay, Ekmel (IEEE, 2019)
    In this paper design, fabrication and measurement of a GaN HEMT based Monolithic Microwave Integrated Circuit (MMIC) Low Noise Amplifier (LNA) is presented. 12-Term equivalent circuit modeling is exacuted. Inductive source ...
  • Realistic channel temperature simulation of AlGaN/GaN high electron mobility transistors 

    Odabaşı, Oğuz; Bütün, Bayram; Ekmel, Özbay (IEEE, 2019)
    In this work, the realistic channel temperature of AlGaN/GaN High Electron Mobility Transistors (HEMTs) is investigated by using 2D electrothermal and Finite Element Method (FEM) thermal simulations. By using a special ...
  • X-band high power GaN SPDT MMIC RF switches 

    Osmanoğlu, Sinan; Özbay, Ekmel (IEEE, 2019)
    This paper describes the design results and measured performance of three different high power, low loss and high isolation GaN high electron mobility transistor (HEMT) based single-pole double-throw (SPDT) RF switches. ...
  • Output feedback stabilization by reduced order finite time observers using a trajectory based approach 

    Malisoff, M.; Mazenc, F.; Ahmed, Saeed (IEEE, 2019)
    We use finite time reduced order continuous-discrete observers to solve an output feedback stabilization problem for a class of nonlinear time-varying systems whose outputs contain uncertainty. Unlike earlier works, our ...
  • Stochastic driver modeling and validation with traffic data 

    Albaba, Mert; Yıldız, Yıldıray; Li, N.; Kolmanovsky, I.; Girard, A. (IEEE, 2019)
    This paper describes a stochastic modeling approach for predicting driver responses in highway traffic. Different from existing approaches in the literature, the proposed modeling framework allows simultaneous decision ...
  • Distributed output feedback control of decomposable lpv systems with delay: Application to multi-agent nonholonomic systems 

    Zakwan, Muhammad; Ahmed, Saeed (IEEE, 2019)
    This paper presents distributed output feedback control of a class of distributed linear parameter varying systems with a parameter-dependent time-varying delay. A delaydependent bounded-real lemma approach, based on ...
  • Controller design for delay margin improvement 

    Gündeş, A. N.; Özbay, Hitay (IEEE, 2019)
    Two important design objectives in feedback control are steady-state error minimization and delay margin maximization. In general these two objectives work against each other. This paper starts with an initial controller ...
  • FEM Based design and simulation tool for MRI birdcage coils Including eigenfrequency analysis 

    Gürler, Necip; İder, Yusuf Ziya (2012)
    Radio Frequency (RF) birdcage coils are widely used in Magnetic Resonance Imaging (MRI). Before the actual construction of the coil, not only calculating the capacitance value, which is necessary for the coil to resonate ...
  • HMM Based behavior recognition of laboratory animals 

    Sandıkçı, S; Duygulu, Pınar; Özgüler, A. Bülent (ICPR, 2012)
    In pharmacological experiments, a popular method to discover the effects of psychotherapeutic drugs is to monitor behaviors of laboratory mice subjected to drugs by cameras. Automating behavior analysis of laboratory ...
  • Localizing the excitation to reduce scan time using nonlinear gradient fields 

    Kopanoğlu, Emre; Yılmaz, Uğur; Akın, Burak; Açıkel, Volkan; Atalar, Ergin (ISMRM, 2012)
    elatively low SAR, but they cannot excite local regions and therefore causes long scan times. Although small volumes can be excited using multi-dimensional excitation pulses, such pulses are long and/or have relatively ...
  • Decreasing SAR of a multi-dimensional central brightening inhomogeneity correction pulse using nonlinear gradient fields and VERSE 

    Kopanoğlu, Emre; Gökhalk, Yıldıray; Yılmaz, Uğur; Açıkel, Volkan; Atalar, Ergin (ISMRM, 2012)
    To correct for B1 inhomogeneity artifacts, multi-dimensional pulses are widely used. However, such pulses increase SAR significantly. In this study, we compare, and combine two SAR reduction methods, the variable rate ...

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