Elektrik Elektronik Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/411
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Editorial Citation - WoS: 1Citation - Scopus: 1Editorial: Optical Wave Propagation and Communication in Turbulent Media(Frontiers Media Sa, 2023) Baykal, YahyaArticle Citation - WoS: 3Citation - Scopus: 3Finite Element Method-Based Optimisation of Magnetic Coupler Design for Safe Operation of Hybrid Uavs(Mdpi, 2023) Iskender, Ires; Navruz, Tugba Selcen; Arslan, SamiThe integration of compact concepts and advances in permanent-magnet technology improve the safety, usability, endurance, and simplicity of unmanned aerial vehicles (UAVs) while also providing long-term operation without maintenance and larger air gap use. These developments have revealed the demand for the use of magnetic couplers to magnetically isolate aircraft engines and starter-generator shafts, allowing contactless torque transmission. This paper explores the design aspects of an active cylindrical-type magnetic coupler based on finite element analyses to achieve an optimum model for hybrid UAVs using a piston engine. The novel model is parameterised in Ansys Maxwell for optimetric solutions, including magnetostatics and transients. The criteria of material selection, coupler types, and topologies are discussed. The Torque-Speed bench is set up for dynamic and static tests. The highest torque density is obtained in the 10-pole configuration with an embrace of 0.98. In addition, the loss of synchronisation caused by the piston engine shaft locking and misalignment in the case of bearing problems is also examined. The magnetic coupler efficiency is above 94% at the maximum speed. The error margin of the numerical simulations is 8% for the Maxwell 2D and 4.5% for 3D. Correction coefficients of 1.2 for the Maxwell 2D and 1.1 for 3D are proposed.Article Citation - WoS: 4Citation - Scopus: 4Design and Implementation of a Mhz Frequency Transformer With a Ferromagnetic Fluid Core(Mdpi, 2023) Hatem, Sude; Kurt, ErolDesign and optimization of a magnetic fluid cored transformer are studied for high frequency applications. An easy and cheap fluid core is designed and used to decrease the eddy current and loses, thereby low conducting and paramagnetic features are added. The core exhibits both fluid and solid characteristics exerting high frequency modes in the fluid and low current due to the iron powder inside. The finite element analysis simulations are performed via COMSOL Multi-physics package for different mass fractions of iron powder. The maximum peak-to-peak voltage and power are found as 526 mV and 188.8 mW at 12 MHz from the simulations. 3D patterns prove that the magnetic flux and magnetization exhibit turbulence in the core, thereby localized magnetic values indicate an arbitrary attitude for various frequencies. Optimum mass fraction is found as 0.7, which is parallel with experimental results. The transformer operates between 11 MHz and 13.5 MHz optimally.Article Citation - WoS: 8Citation - Scopus: 8Analysis of Quantum Radar Cross-Section by Canonical Quantization Method (Full Quantum Theory)(Ieee-inst Electrical Electronics Engineers inc, 2020) Salmanogli, Ahmad; Gokcen, DincerThis article investigates the difference between two quantum-based theories to calculate the radar cross-section (RCS). Quantum radar cross-section (QRCS) has been commonly analyzed using the dipole approximation method, and the related results show that it can improve the sidelobe of the interference pattern in contrast to the classical methods. This study, on the other hand, utilizes the canonical quantization (or microscopic) method, which is a more comprehensive theory than the dipole approximation method to calculate the radar cross-section. It is shown that there are some similarities between two methods; nonetheless, there are some crucial quantities and factors that have been ignored in the dipole approximation methods. The main difference arises due to the interaction Hamiltonian that two methods relied on. The theoretical calculation shows some critical points suggesting that the dipole approximation method cannot cover all aspects of the radar cross-section calculation. To verify the mentioned point, we establish a new method in which the radar cross-section is calculated by merging the quantum approach with the method of moment (MoM), called quantum-method of moment (QMoM). The simulation results show that the newly established method is in harmony with the canonical quantization method.Article Citation - WoS: 23Citation - Scopus: 23Entanglement of Optical and Microcavity Modes by Means of an Optoelectronic System(Amer Physical Soc, 2019) Salmanogli, Ahmad; Gokcen, Dincer; Gecim, H. SelcukEntanglement between optical and microwave cavity modes is a critical issue in illumination systems. Optomechanical systems are utilized to introduce coupling between the optical and microwave cavity modes. However, due to some restrictions of the optomechanical system, especially sensitivity to the thermal photon noise at room temperature, an alternative optoelectronic system is designed to address the problem. We study a method by which it may be possible to remove the mechanical part of the previous systems to minimize the thermally generated photons. Unlike optomechanical systems, in our system, the optical mode is directly coupled to the microwave cavity mode through the optoelectronic elements without employing any mechanical parts. The utilized approach leads to generating the entangled modes at room temperature. For this purpose, the dynamics of the motion of the optoelectronic system is theoretically derived using the Heisenberg-Langevin equations from which one can calculate the coupling between optical and microwave cavity modes. The direct coupling between the optical and microwave cavity modes is the most important feature and is achieved through the combination of the photodetector and a Varactor diode. Hence, by controlling the photodetector current, that is, the photocurrent, depending on the optical cavity incident wave and the Varactor diode-biased voltage, the coupling between the optical and microwave cavity modes is established. The voltage across the Varactor diode also depends on the generated photocurrent. Consequently, our results show that the coupled modes are entangled at room temperature without the requirement for any mechanical parts.Article Citation - WoS: 4Citation - Scopus: 4Large-Scale Hyperspectral Image Compression Via Sparse Representations Based on Online Learning(Univ Zielona Gora Press, 2018) Ulku, Irem; Kizgut, ErsinIn this study, proximity based optimization algorithms are used for lossy compression of hyperspectral images that are inherently large scale. This is the first time that such proximity based optimization algorithms are implemented with an online dictionary learning method. Compression performances are compared with the one obtained by various sparse representation algorithms. As a result, proximity based optimization algorithms are listed among the three best ones in terms of compression performance values for all hyperspectral images. Additionally, the applicability of anomaly detection is tested on the reconstructed images.Article Citation - WoS: 112Citation - Scopus: 127Wave Structure Function and Spatial Coherence Radius of Plane and Spherical Waves Propagating Through Oceanic Turbulence(Optical Soc Amer, 2014) Lu, Lu; Ji, Xiaoling; Baykal, YahyaThe analytical formulae for the wave structure functions (WSF) and the spatial coherence radius of plane and spherical waves propagating through oceanic turbulence are derived. It is found that the Kolmogorov five-thirds power law of WSF is also valid for oceanic turbulence in the inertial range. The changes of the WSF and the spatial coherence radius versus different parameters of oceanic turbulence are examined. (C) 2014 Optical Society of America.