Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Conference Object Citation - Scopus: 2Compact Proton Accelerator in Uhf Band at Kahvelab(JACoW Publishing, 2022) Esen, S.; Adıgüzel, A.; Koçer, O.; Çağlar, A.; Çelebi, E.; Öz, S.; Özcan, V.E.; Karatay, Anıl; Yaman, Fatih; Yılmaz, Hasan ÖnderProton Test Beam at KAHVELab (Kandilli Detector, Accelerator and Instrumentation Laboratory) project aims to design and produce a radio frequency quadrupole (RFQ) operating at 800 MHz in Istanbul, Turkey using the local resources. The beamline consists of a proton source, a low energy beam transport (LEBT) line including the beam diagnostic section and the RFQ cavity itself. This RFQ is 4-vane, 1-meter-long cavity to accelerate the 20 keV beam extracted from plasma ion source to 2 MeV. Its engineering prototype is already produced and subjected to mechanical, low power RF and vacuum tests. In this study, the results of the first test production, especially the bead-pull test setup will be discussed. © 2022 Proceedings - Linear Accelerator Conference, LINAC. All rights reserved.Conference Object Citation - Scopus: 2Rf Measurements and Tuning of the Test Module of 800 Mhz Radio-Frequency Quadrupole(JACoW Publishing, 2022) Kılıçgedik, A.; Adıgüzel, A.; Esen, S.; Baran, B.; Çağlar, A.; Çelebi, E.; Özcan, V. E.; Kaya, U.; Türemen, G.; Ünel, N. G.; Yaman, FatihThe 800 MHz RFQ (radio-frequency quadrupole), developed and built at KAHVElab (Kandilli Detector, Accelerator and Instrumentation Laboratory) at Bogazici University in Istanbul, Turkey, has been designed to provide protons that have an energy of 2 MeV within only 1 m length. The RFQ consists of two modules and the test module of RFQ was constructed. The algorithm developed by CERN, based on the measurements generated by the tuner settings estimated through the response matrix [1, 2, 3], has been optimized for a single module and 16 tuners. The desired field consistent with the simulation was obtained by bead-pull measurements. In this study, we present low-power rf measurements and field tuning of the test module. © 2022 Proceedings - Linear Accelerator Conference, LINAC. All rights reserved.Conference Object Citation - Scopus: 8Localization of a Passive Molecular Transmitter With a Sensor Network(Springer, 2020) Güleç, Fatih; Atakan, BarışMacroscale molecular communication (MC), which has a potential for practical applications, is a promising area for communication engineering. In a practical scenario such as monitoring air pollutants released from an unknown source, it is essential to estimate the location of the molecular transmitter (TX). This paper presents a novel Sensor Network-based Localization Algorithm (SNCLA) for passive transmission by using a novel experimental platform which mainly comprises a clustered sensor network (SN) with 24 sensor nodes and evaporating ethanol molecules as the passive TX. With the usage of the SN concept, novel methods can be developed for the problems in macroscale MC by utilizing the wide literature of sensor networks. In SNCLA, Gaussian plume model is employed to derive the location estimator. The parameters such as transmitted mass, wind velocity, detection time and actual concentration are calculated or estimated from the measured signals via the SN to be employed as the input for the location estimator. The numerical results show that the performance of SNCLA is better for stronger winds in the medium. Our findings show that evaporated molecules do not propagate homogeneously through the SN due to the presence of the wind. In addition, the estimation error of SNCLA decreases for higher detection threshold values. © 2020, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.Conference Object Citation - WoS: 14Citation - Scopus: 14An Overview of the Recent Advances in Fbg-Assisted Phase-Sensitive Otdr Technique and Its Applications(IEEE, 2020) Yüksel, Kıvılcım; Koçal, Ertunga Burak; Jason, Johan; Wuilpart, Marc; Sainz, Manuel Lopez-AmoIn this paper, we discuss the operation principles, sensing mechanism, challenges and application areas of FBG-assisted phase-sensitive optical time-domain reflectometry. A special emphasis is given to the interrogation of fiber Bragg grating arrays for vibration sensing application. Results obtained by different research groups are compared in terms of performance characteristics and future perspectives. Recent progress obtained through our research collaboration are also presented. In particular, the detrimental spectral shadowing effect and multiple reflection crosstalk are analysed and mitigation techniques are proposed. © 2020 IEEE.Article Citation - WoS: 4Citation - Scopus: 4Adaptive Visual Servo Regulation Control for Camera-In Configuration With a Fixed Camera Extension(ACTA Press, 2009) Tatlıcıoğlu, Enver; Dawson, Darren M.; Xian, B.In this paper, image-based regulation control of a robot manipulator with an uncalibrated vision system is discussed. To compensate for the unknown camera calibration parameters, a novel prediction error formulation is presented. To achieve the control objectives, a Lyapunov-based adaptive control strategy is employed. The control development for the camera-in-hand problem is presented in detail and a fixed-camera problem is included as an extension.Conference Object Index Modulation of Transient Grating in Nonlinear Medium(SPIE, 2016) Karakılınç, Özgür Önder; Dinleyici, Mehmet SalihA transient chirped grating structure is formed by beam interferences in nonlinear photonic crystal waveguide. Pulse propagation in nonlinear transient grating media is investigated and its impact on the transmission dynamics is explored. The grating may not be stationary propagating but anharmonically oscillating. Thus, effective modification of the refractive index needs to be evaluated in detail.Conference Object Citation - Scopus: 1Fs Fbgs as Probes To Monitor Thermal Regeneration Mechanisms(SPIE, 2019) Chah, K.; Kinet, D.; Yüksel, Kıvılcım; Caucheteur, C.This paper shows that fiber Bragg gratings written in standard single mode optical fiber with IR femtosecond pulses and point-by-point technique are high temperature resistant (< 1000 degrees C). Moreover, after calibration process, these gratings can be used as a reference to study and discriminate between different high temperature annealing mechanisms involved in other types of gratings and/or fibers. Here we have considered the regeneration process of gratings written by UV laser in boron/germanium co-doped single mode optical fiber. Hence, the monitoring of grating strength and differential wavelength shift between femtosecond and type-I gratings during annealing cycle yields the wavelength shift due to the annealing of doping (mainly boron) and UV-related defects and their relative contributions to the regeneration mechanism.Article Citation - WoS: 1Citation - Scopus: 1Temperature and Pressure Dependence of the Raman Intensity and Frequency of a Soft Mode Near the Tricritical Point in the Ferroelectric Sbsi(Taylor & Francis, 2016) Yurtseven, Hasan Hamit; Duman, SinemWe analyze the pressure dependence of the intensity and the frequency of a soft mode from the Raman and elastic light scattering experiments as reported in the literature close to the ferroelectric - paraelectric transition in SbSI crystal. The Raman intensity of this mode is analyzed as a function of pressure at constant temperatures of 272K (first order transition) and 234K (tricritical or second order transition) according to a power-law formula. Our analysis of the Raman intensity gives closely the mean field values for the order parameter. From our analysis, we also obtain that the Raman frequency (squared) of the soft mode varies linearly with the pressure at constant temperatures close to the ferroelectric - paraelectric transition in SbSI as obtained experimentally.Article Citation - WoS: 6Citation - Scopus: 7Neural Network Based Robust Control of an Aircraft(ACTA Press, 2020) Tanyer, İlker; Tatlıcıoğlu, Enver; Zergeroǧlu, ErkanOutput tracking control of an aircraft subject to uncertainties in the dynamic model and additive state-dependent nonlinear disturbancelike terms is aimed. Uncertainties in the aircraft dynamic model yield an uncertain input gain matrix, which is neither positive definite nor symmetric and an uncertain term in the error dynamics. To deal with the uncertain input gain matrix, a decomposition method is utilized to put error dynamics in a form where an uncertain positive definite matrix multiplies the auxiliary error but this results in the control input to be pre-multiplied first with a unity upper triangular matrix which is uncertain and then with a known diagonal matrix. A novel controller composed of a neural network compensation term and an integral of signum of error is designed. A novel Lyapunov type stability analysis is utilized to prove global asymptotic tracking of output of a reference model. Extensive numerical simulations are presented to demonstrate the efficacy of the proposed controller where robustness to variation of initial states and a comparison with a robust controller are also shown. © 2020 Acta Press. All rights reserved.Conference Object Kahve Laboratory Rf Circulator and Transmission Line Project(American Institute of Physics, 2018) Çetinkaya, Hakan; Çağlar, Aslıhan; Çicek, Cihan; Özbey, Aydın; Sunar, Ezgi; Türemen, Görkem; Yıldız, Hüseyin; Yüncü, Alperen; Özcan, Erkcan; Ünel, Gökhan; Yaman, FatihAn 800 MHz RF circulator and transmission line project has recently started at the newly commissioned Kandilli Detector, Accelerator and Instrumentation (KAHVE) Laboratory at the Boǧaziçi University. The aims are to design, build and construct an RF circulator and transmission line in Turkey for high power and high frequency applications. The project consists of 8 transmission line elements: 800 MHz RF generator with 60 kW power (klystron), klystron to waveguide converter, waveguides, E and H bends, 3-port circulator and waveguide to coaxial converter to transmit RF power to a pillbox RF cavity. Design studies and details of the ongoing project will be presented.