Electrical & Electronics Engineering
Permanent URI for this collectionhttps://hdl.handle.net/10679/44
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Book ChapterPublication Metadata only IEEE 802.15.7: Visible light communication standard(2017-01-01) Uysal, Murat; Edemen, Çağatay; Baykaş, T.; Sarbazi, E.; Shams, P.; Uğurdağ, Hasan Fatih; Celebi, H.; Electrical & Electronics Engineering; UYSAL, Murat; EDEMEN, Çağatay; UĞURDAĞ, Hasan FatihVisible light communications (VLC) use the visible spectrum (wavelengths of 390-750 nm or frequency band of 400-790 THz) and provide wireless communication using omnipresent light-emitting diodes (LEDs). Since the human eye perceives only the average intensity when light changes fast enough, it is possible to transmit data using LEDs without a noticeable effect on the lighting output and the human eye. Simultaneous use of LEDs for both lighting and communications purposes is a sustainable and energy-efficient approach that has the potential to revolutionize how we use light. VLC can be used in a wide range of short- and medium-range communication applications including wireless local, personal, and body area networks (WLAN, WPAN, and WBANs), vehicular networks, and machine-to-machine communication among many others. Besides energy efficiency, VLC offer several other inherent advantages over radio frequency (RF)-based counterparts, such as immunity to electromagnetic interference, operation on unlicensed bands, additional physical security, and a high degree of spatial confinement allowing a high reuse factor.Conference paperPublication Open Access CL-FedFR: Curriculum learning for federated face recognition(SciTePress , 2024-02-29) Dube, D. C.; Eroğlu Erdem, Ciğdem ; Korcak, Ö.; Electrical & Electronics Engineering; ERDEM, Çiğdem EroğluFace recognition (FR) has been significantly enhanced by the advent and continuous improvement of deep learning algorithms and accessibility of large datasets. However, privacy concerns raised by using and distributing face image datasets have emerged as a significant barrier to the deployment of centralized machine learning algorithms. Recently, federated learning (FL) has gained popularity since the private data at edge devices (clients) does not need to be shared to train a model. FL also continues to drive FR research toward decentralization. In this paper, we propose novel data-based and client-based curriculum learning (CL) approaches for federated FR intending to improve the performance of generic and client-specific personalized models. The data-based curriculum utilizes head pose angles as the difficulty measure and feeds the images from “easy” to “difficult” during training, which resembles the way humans learn. Client-based curriculum chooses “easy clients” based on performance during the initial rounds of training and includes more “difficult clients” at later rounds. To the best of our knowledge, this is the first paper to explore CL for FR in a FL setting. We evaluate the proposed algorithm on MS-Celeb-1M and IJB-C datasets and the results show an improved performance when CL is utilized during training.ArticlePublication Metadata only Theoretical analysis of magneto-inductive THZ wireless communications and power transfer with multi-layer graphene nano-coils(IEEE, 2017-03) Gülbahar, Burhan; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitGraphene with significant potentials in diverse areas of physical and biological sciences is proposed as a solution to complementary problems of semiconductor and biomedical industries, i.e., the on-chip (OC) interconnect bottleneck and in-body (IB) wireless communications/power transfer (PT), respectively. Emerging nanoscale solutions with radio frequency, optical, ultrasonic, or molecular channels in OC and IB media have various challenges including achievable footprints and frequency, energy consumption, medium dependent features, and interference. In this paper, major challenges are addressed with magneto-inductive (MI) transceivers by combining the advantages of THz operation frequency, unique features of intercalated multi-layer graphene (MLG) coils and range extension with MI waveguides. Our design promises scalable and high performance solutions for the OC interconnect bottleneck while providing biocompatible and universal solutions for challenging IB medium. The proposed solution is theoretically analyzed and numerically compared with the copper-based alternatives, and the practical challenges are discussed. Simulation results achieve high capacity (several Tbit/s) and ultra-low power (500 zJ/bit) wireless communications while providing high (hundreds of kWs) and efficient (109 W/mm2) wireless PT at several millimeters. In addition, unique properties of MLG such as lightweight structure, biocompatibility, current carrying capacity, and planar manufacturability make the solution more promising for challenging environments.Conference paperPublication Metadata only Multicore energy efficient scheduling with energy harvesting for wireless multimedia sensor networks(IEEE, 2017-07-02) Jamshed, M. A.; Amjad, Osama; Zeydan, E.; Amjad, OsamaWireless Multimedia Sensor Networks (WMSNs) are becoming one of the latest trends in the Internet of things. However, in WMSNs the energy constraint is a significant issue. In this paper, an idea of integrating energy harvesting technique with energy efficient scheduling mechanism is proposed. In order to increase the overall energy efficiency, the previously studied scheduling algorithm is used and integrated with a multi-core processor technique. Since increasing the number of cores in a processor decreases the overall energy efficiency, integration of energy harvesting with the processor can alleviate energy loss. The proposed idea constitutes of implementing the technique of lightweight processor (LWP) on a first core and leaving the second core in idle state with multiple lightweight processor implementation. The second core is divided into two parts namely, the main part and the multiple LWPs. The main part of the second core is used to relieve the processing speed issue and the multiple LWPs are used to cover up the flaws of missing deadlines if the number of tasks are increased. The second core comes in operation when the battery capacity is above 50%, using the RF energy harvesting scheme. This method increases the overall energy efficiency of each sensor node from 38% to 60% compared to the single core and single LWP method.ArticlePublication Metadata only Energy harvesting and magneto-inductive communications with molecular magnets on vibrating graphene and biomedical applications in the kilohertz to terahertz band(IEEE, 2017-09) Gülbahar, Burhan; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitMagneto-inductive (MI) Terahertz (THz) wireless channels provide significant theoretical performances for MI communications (MIC) and wireless power transmission (WPT) in nanoscale networks. Energy harvesting (EH) and signal generation are critical for autonomous operation in challenging mediums including biomedical channels. State of the art electromagnetic vibrational devices have millimeter dimensions while targeting low frequency EH without any real-time communications. In this paper, graphene resonators are combined with single molecule magnets (SMMs) to realize nanoscale EH, MIC, and WPT with novel modulation methods achieving simultaneous wireless information and PT. The unique advantages of graphene including atomic thickness, ultra-low weight, high strain, and resonance frequencies in the Kilohertz to THz band are combined with high and stable magnetic moments of Terbium (III) bis (phthalocyanine) SMMs. Numerical analyses provide tens of nanowatts powers and efficiencies of 10 4W/m3 in acoustic and ultrasound frequencies comparable with vibrational EH devices while millimeter wave carrier generation is numerically analyzed. Proposed model and communication theoretical analysis present a practical framework for challenging applications in the near future by promising simple mechanical design. Applications include nanoscale biomedical tagging including human cells, sensing and communication for diagnosis and treatment, EH and modulation for autonomous nano-robotics, and magnetic particle imaging.EditorialPublication Metadata only Welcome note from the general chairs(IEEE, 2017-12-13) Elfadel, I. A. M.; Uğurdağ, Hasan Fatih; Electrical & Electronics Engineering; UĞURDAĞ, Hasan FatihThe following topics are dealt with: low-power electronics; system-on-chip; integrated circuit design; CMOS integrated circuits; microprocessor chips; SRAM chips; logic design; flip-flops; power aware computing; MOSFET circuits.Conference paperPublication Metadata only Impact of cyber-security breach to price signals on power market: An experimental human simulation(IEEE, 2018) Poyrazoğlu, Göktürk; Oh, H. S.; Electrical & Electronics Engineering; POYRAZOĞLU, GöktürkThe market power is a term defined in power economics as a potential to make the electric power market volatile. A supplier having the market power has an opportunity to speculate on the market clearing price. Observance of the market power may be destructive for the system only if a supplier actually exercises its potential. Although there are several studies on the assessment of market power, there is no study showing the consequences if a supplier stealthy exercises its market power. In order to fill this gap in the literature, a multi-player electric market game is developed and a realistic market environment is simulated with the participation of engineering students. Mainly the cyber-security issue in conjunction with the market power is focused in this study. For a limited number of periods, price information is intentionally corrupted via cyber-attack to create a misbelief at the supplier side. The analysis of the results showed that if a participant is under the impression of possessing the market power regardless actual possession, he/she would try to exercise it to raise its profit, and as a result, market clearing price starts to fluctuate.Conference paperPublication Metadata only Comparison of DC-link capacitor types under various grid conditions(IEEE, 2019-04) Bilgin, M. S.; Poyrazoğlu, Göktürk; Aktem, M.; Er, E.; Electrical & Electronics Engineering; POYRAZOĞLU, GöktürkA DC/AC converter can face negative conditions of power systems such as instability. One of the most crucial necessities of the grid is voltage stability. There are some effects of voltage unbalance for grid-tied DC/AC converters. Grid voltage unbalance causes higher THD values on grid currents than normal grid conditions. THD value of grid current is limited by the IEEE 519-2014 standard. Unstable grid conditions show different results because of the value and type of DC-Link capacitors. In this paper, two types of capacitors are compared with different grid voltage conditions and power factor values for grid-tied 10kVA DC/AC converter. Simulation results are shown and interpreted.ArticlePublication Open Access Depression screening from voice samples of patients affected by parkinson’s disease(S. Karger AG, 2019-05-01) Özkanca, Yasin Serdar; Öztürk, M. G.; Ekmekci, Merve Nur; Atkins, D. C.; Demiroğlu, Cenk; Ghomi, R. H.; Electrical & Electronics Engineering; DEMİROĞLU, Cenk; Özkanca, Yasin Serdar; Ekmekci, Merve NurDepression is a common mental health problem leading to significant disability worldwide. It is not only common but also commonly co-occurs with other mental and neurological illnesses. Parkinson's disease (PD) gives rise to symptoms directly impairing a person's ability to function. Early diagnosis and detection of depression can aid in treatment, but diagnosis typically requires an interview with a health provider or a structured diagnostic questionnaire. Thus, unobtrusive measures to monitor depression symptoms in daily life could have great utility in screening depression for clinical treatment. Vocal biomarkers of depression are a potentially effective method of assessing depression symptoms in daily life, which is the focus of the current research. We have a database of 921 unique PD patients and their self-assessment of whether they felt depressed or not. Voice recordings from these patients were used to extract paralinguistic features, which served as inputs to machine learning and deep learning techniques to predict depression. The results are presented here, and the limitations are discussed given the nature of the recordings which lack language content. Our models achieved accuracies as high as 0.77 in classifying depressed and nondepressed subjects accurately using their voice features and PD severity. We found depression and severity of PD had a correlation coefficient of 0.3936, providing a valuable feature when predicting depression from voice. Our results indicate a clear correlation between feeling depressed and PD severity. Voice may be an effective digital biomarker to screen for depression among PD patients.Conference paperPublication Metadata only Entanglement demonstration on board a nano-satellite(Optica Publishing Group, 2020) Villar, A.; Lohrmann, A.; Bai, X.; Vergoosen, T.; Bedington, R.; Perumangatt, C.; Lim, H. Y.; Islam, T.; Reezwana, A.; Tang, Z.; Chandrasekara, R.; Sachidananda, S.; Durak, Kadir; Wildfeuer, C. F.; Griffin, D.; Oi, D. K. L.; Ling, A.; Electrical & Electronics Engineering; DURAK, KadirPolarization entangled photon-pairs are generated and detected onboard a 3U CubeSat in low-Earth orbit that violate Bell’s inequality with a CHSH parameter of 2.60 ± 0.06. These results pave the way for space-based quantum networks.Conference paperPublication Metadata only Photon statistics effects on a QRNG of vacuum fluctuations(Optica Publishing Group, 2020-09-14) Dandaşi, Abdulrahman; Özel, Helin; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Dandaşi, Abdulrahman; Özel, HelinOptical scattering enhances randomness characteristics, increases the chaotic behavior of coherent sources, broadens the distribution of photon statistics and makes it super-Poissonian which allows faster sampling compared to Poissonian.Conference paperPublication Metadata only Down-conversion emission profile characterisation via camera(Optica Publishing Group, 2020-12-14) Kuniyil, Hashir Puthiyapurayil; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Kuniyil, Hashir PuthiyapurayilWe present a method to improve the brightness and collection efficiency of the spontaneous parametric down-conversion source by monitoring the mode shape using camera and correcting it with collection optics.Conference paperPublication Metadata only Low-complexity interference reduction for gfdm systems using corrective coefficients(IEEE, 2022) Jirdehi, A. A.; Abdolee, R.; Tazehkand, B. M.; Aghdam, Mohammad Reza Ghavidel; Electrical & Electronics Engineering; AGHDAM, Mohammad Reza GhavidelGeneralized Frequency Division Multiplexing (GFDM) is a promising multi-carrier modulation scheme for next-generation wireless communication systems. GFDM uses a non-orthogonal pulse shape, which leads to self-interference among sub-carriers. In this paper, we propose a new coded GFDM method to reduce the self-interference in each block by using a space-frequency block coding (SFBC) scheme. To this end, we introduce corrective coefficients based on channel state information and the demodulation matrix for each modulated data. We evaluate the bit error rate (BER) performance of the system by comparing SFBC-GFDM transmission in Rayleigh channels with a matched filter (MF) receiver. Our computer simulations show that the proposed scheme substantially improves the system performance in BER. Per our results presented in this paper, we achieve 5 dB performance improvement at BER of 10-2 compared to previous counterparts.Conference paperPublication Metadata only Multi-objective control of nine-level anpc converters: a robust and gain-free mpc method(IEEE, 2023) Harbi, İ.; Makhamreh, Hamza; Ahmed, Mostafa; Abdelrahem, M.; Heldwein, M.; Rodriguez, J.; Kennel, R.; Electrical & Electronics Engineering; MAKHAMREH, Hamza Ahmed MousaModel predictive control (MPC) is a powerful control method for addressing multi-objective control problems, however, one of its main challenges is the cumbersome tuning process of the weighting factors. This paper presents a weighting factorless advanced MPC method for a recently developed nine-level active neutral point clamped (ANPC) converter, which has several advantages over conventional and recent nine-level topologies, such as low number of used switches and flying capacitors (FCs), reduced voltage rating of FCs and high efficiency. The developed MPC method avoids the use of weighting factors while addressing three control objectives: current control, FCs balancing and neutral point (NP) control. Similar to conventional finite-set MPC (FS-MPC), the presented method has high performance in terms of all control objectives. Moreover, this method exhibits enhanced robustness to parameter mismatch compared to the conventional scheme. The effectiveness of this method is validated through experimental testing under various operating conditions. The research demonstrates the potential for this technique to address control problems in ANPC-based converters and highlights its potential for further applications.ArticlePublication Open Access An efficient versatile video coding motion estimation hardware(Springer, 2024-04) Ahmad, W.; Mahdavi, H.; Hamzaoğlu, İlker; Computer Science; HAMZAOĞLU, IlkerVersatile Video Coding (VVC) is the latest video coding standard. It provides higher compression efficiency than the previous video coding standards at the cost of significant increase in computational complexity. Motion estimation (ME) is the most time consuming and memory intensive module in VVC encoder. Therefore, in this paper, we propose an efficient VVC ME hardware. It is the first VVC ME hardware in the literature. It has real time performance with small hardware area. This efficiency is achieved by using a 64 × 64 systolic processing element array to support maximum coding tree unit (CTU) size of 128 × 128 and by using a novel memory-based sum of absolute differences (SAD) adder tree to calculate SADs of 128 × 128 CTUs. The proposed VVC ME hardware reduces memory accesses significantly by using an efficient data reuse method. It can process up to 30 4 K (3840 × 2160) video frames per second.ArticlePublication Metadata only Eliminating intrinsic interference in GFDM systems: Design of a complex-valued prototype filter(Elsevier, 2024-04) Aghdam, Mohammad Reza Ghavidel; Mozaffari Tazehkand, B.; Abdolee, R.; Electrical & Electronics Engineering; AGHDAM, Mohammad Reza GhavidelPrototype filter design is a critical challenge in generalized frequency division multiplexing (GFDM) systems. Poorly designed filters can result in inherent and out-of-band (OOB) interferences, severely impacting system performance. This paper proposes a novel solution to this problem by introducing an optimal prototype filter that mitigates the adverse effects of intrinsic interferences in GFDM systems. Our approach involves using a complex-valued prototype filter, which resembles a single-sideband (SSB) modulation scheme and significantly enhances bandwidth efficiency compared to conventional GFDM. To design the optimal filter, we formulate an optimization problem that eliminates inband and adjacent subcarriers intrinsic interferences. We also provide analytical expressions for evaluating the system's bit error rate (BER) and demonstrate the superiority of our optimized prototype filter over its current counterparts. To validate the design of the proposed prototype filter, we assess the noise enhancement factor (NEF). Our results indicate that our proposed filter improves system performance and reduces BER in GFDM systems.Conference paperPublication Metadata only Deep learning based event recognition in aerial imagery(IEEE, 2023) Şahin, A. H.; Ateş, Hasan Fehmi; Electrical & Electronics Engineering; ATEŞ, Hasan FehmiIn this paper, we investigate event recognition for aerial surveillance. This is a significant task especially when we consider the growing popularity of UAVs. The main purpose of the paper is to detect events both at the clip level in aerial videos and also at the frame level in aerial images. To achieve this goal, novel deep learning models and training techniques are used. In this work, we propose new model architectures to detect events in both image and video domains. The developed models are tested on the ERA dataset. Results show that the proposed models achieve state-of-the-art performance on both single images and aerial video clips of the ERA dataset.Conference paperPublication Metadata only Blood clotting time measurement using a miniaturized high-frequency ultrasound sensor(IEEE, 2023) Sobhani, M. R.; Majidi, Negar; Yaralıoğlu, Göksen Göksenin; Electrical & Electronics Engineering; YARALIOĞLU, Göksen Göksenin; Majidi, NegarThis paper demonstrates a novel blood coagulation time measurement methodology that requires as low as 1 microliter of whole blood. The blood sample is placed on the top surface of a fused quartz plate where an ultrasonic transducer is fabricated on the bottom surface. The location of the blood sample is aligned with the transducer; therefore, the reflected acoustic waves from the blood/quartz interface are captured and converted to electrical signals by the transducer. The transducer is made of an 8 μm thick zinc oxide (ZnO) thin film that operates at 400 MHz. The acoustic impedance of blood changes due to the coagulation process. This affects the reflection coefficient and amplitude of the reflected waves from the blood/quartz interface. Thus, the blood coagulation time is determined by monitoring the amplitude of reflected acoustic waves. In the experiments, whole blood was used without any sample preparation. The method was tested using citrated blood with calcium chloride and activated partial thromboplastin (aPTT) reagents. We observed that aPTT coagulation times lengthened from 25 sec. to 47 sec. with the addition of heparin. The proposed method has the potential to be used in a disposable low-cost portable coagulation time measurement cartridge for patient self-testing.Conference paperPublication Metadata only Reducing charging costs for electric vehicles with bi-directional charging(IEEE, 2023) Zincircioğlu, Emircan; Bebek, Özkan; Mechanical Engineering; BEBEK, Özkan; Zincircioğlu, EmircanElectric vehicles (EVs) have gained popularity as eco-friendly and energy-efficient modes of transportation. How-ever, the high cost of charging infrastructure remains a significant barrier to the widespread adoption of EVs. Bidirectional charging (BDC) is a promising solution that allows EVs to charge from the grid and supply excess power back to the grid. In this paper, we present a simulation-based study of BDC using MATLAB/Simulink and Simscape to explore the potential of BDC to reduce charging costs. We modeled an EV charging station equipped with BDC capabilities and evaluated the cost savings achieved through BDC under two different scenarios. Our findings suggest that BDC has the potential to reduce charging costs significantly, making EVs more economically viable.Conference paperPublication Metadata only Is visible light communications suitable for using in lane-changing maneuvers?(IEEE, 2023) Meghraoui, A.; Tayebi, M. L.; Besseghier, M.; Yahia, S.; Eldeeb, Hossıen Badr; Vo, V. N.; Ho, T. D.; Electrical & Electronics Engineering; ELDEEB, Hossien Badr HossienLane-changing behaviour is a crucial aspect of driving that requires a safe and efficient driving environment. To achieve this, an accurate perception of the surrounding vehicles and environment is essential, enabling the vehicle to make informed lane-changing decisions and ultimately improving the process's reliability and success rate. This paper uses a non-sequential ray channel modelling approach to investigate visible light communication (VLC) in lane change applications. The vehicle's headlamps and taillights act as wireless transmitters, while photo-detectors on other vehicles act as wireless receivers. The system performance is evaluated in terms of bit error rate (BER), spectral efficiency, and packet delivery ratio (PDR) for different inter-vehicle distances and lateral shifts. The effect of vehicle velocity on the system performance is also investigated. The results demonstrated that VLC could be qualified for exchanging data between the cars for a safe lane change. It also showed significant vehicle position and velocity impacts on the system performance during this process.