Electrical & Electronics Engineering

Permanent URI for this collectionhttps://hdl.handle.net/10679/44

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Open Access
Automatic detection of attachment style in married couples through conversation analysis
(Springer, 2023-05-31) Koçak, Tuğçe Melike; Dibek, B. Ç.; Polat, Esma Nafiye; Kafesçioğlu, Nilüfer; Demiroğlu, Cenk; Electrical & Electronics Engineering; Psychology; KAFESCİOĞLU, Nilüfer; DEMİROĞLU, Cenk; Koçak, Tuğçe Melike; Polat, Esma Nafiye
Analysis of couple interactions using speech processing techniques is an increasingly active multi-disciplinary field that poses challenges such as automatic relationship quality assessment and behavioral coding. Here, we focused on the prediction of individuals’ attachment style using interactions of recently married (1–15 months) couples. For low-level acoustic feature extraction, in addition to the frame-based acoustic features such as mel-frequency cepstral coefficients (MFCCs) and pitch, we used the turn-based i-vector features that are the commonly used in speaker verification systems. Sentiments, positive and negative, of the dialog turns were also automatically generated from transcribed text and used as features. Feature and score fusion algorithms were used for low-level acoustic features and text features. Even though score and feature fusion algorithms performed similar, predictions with score fusion were more consistent when couples have known each other for a longer period of time.
Open Access
Coordinated beamforming design for multi-user multi-cell MIMO VLC networks
(IEEE, 2022-06) Naser, S.; Bariah, L.; Jaafar, W.; Muhaidat, S.; Al-Qutayri, M.; Uysal, Murat; Sofotasios, P. C.; Electrical & Electronics Engineering; UYSAL, Murat
Inter-cell interference (ICI) and inter-user interference (IUI) constitute a major issue towards achieving the optimum spectral efficiency (SE) and energy efficiency (EE) performance in multi-cell visible light communication (VLC) networks. Hence, advanced multiple access techniques need to be leveraged in order to improve the provided service to the users of such interfering networks. To this end, the present contribution proposes the integration of coordinated beamforming (CB) with rate-splitting multiple access (RSMA) in multi-cell VLC systems. Specifically, we consider the design of beamformers for the common and private streams in a coordinated manner between different attocells, which is shown to provide efficient mitigation of the incurred interference. Additionally, the formulated optimization problem aims to minimize the sum of the mean squared error across all attocells in order to jointly determine the optimum receive filters and coordinated transmit beamformers for RSMA streams. In this context, we illustrate through extensive computer simulations, which are carried out in a realistic setup that assumes noisy channel state information acquisition, the distinct flexibility and robustness of CB-based RSMA in mitigating the incurred interference. Finally, the offered results demonstrate the superiority of CB-based RSMA in terms of achievable SE and EE performance in multi-cell VLC networks compared to the conventional CB-based space division multiple access counterpart.
Open Access
Design and analysis of a truncated elliptical-shaped chipless RFID tag
(TÜBİTAK, 2021) Khan, A. T.; Abdullah, Y.; Farhat, S.; Nawaz, Wasim; Rauf, U.; Nawaz, Wasim
This article presents a novel polarization-insensitive chipless radio frequency identification tag having an encoding capacity of 11 bits. The proposed resonator design comprises discontinuous arc slots forming truncated elliptically shape offering 1:1 slot to bit correspondence with suppressed unwanted harmonic resonances. Electromagnetic performance analysis of the proposed tag design is done over an ungrounded Rogers RT duroid® 5880 laminate. The overall tag design covers a footprint of 15 × 15 × 0.508 mm 3 offering convincingly appreciable bit density of 4.88 bits/cm 2. The realized tags are analyzed for real-world electromagnetic performance resulting in an agreement between measured and computed results. The proposed work finds its applications in the food and beverage industry.
Open Access
An efficient versatile video coding motion estimation hardware
(Springer, 2024-04) Ahmad, W.; Mahdavi, H.; Hamzaoğlu, İlker; Computer Science; HAMZAOĞLU, Ilker
Versatile 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.
Open Access
Evaluation of stress and cognition indicators in a puzzle game: Neuropsychological, biochemical and electrophysiological approaches
(Razi Vaccine and Serum Research Institute, 2022-07) Aliyari, H.; Golabi, S.; Sahraei, H.; Daliri, M. R.; Minaei-Bidgoli, B.; Tadayyonıahrab, Hamed; Kazemi, M.; Tadayyonıahrab, Hamed
Video games have significant and diverse effects on stress and cognitive systems based on the game style. The effect of this media on the central nervous system is significant because of its repetition. Nowadays, video games have become an important part of human life at different ages, and therefore, assessing their effects (good and bad) on stress factors, cognition, and behavior can be an important help in understanding the nature of these games and managing their impact on humans. Consequently, this study aimed to investigate the effect of a puzzle game on the player's stress and cognitive indicators in neuropsychological, biochemical, and electrophysiological approaches. A total of 44 participants were entered into the study and randomly assigned to control and experimental groups. Our interventions were watching (control group) and playing (experimental group) the game. Salivary biomarkers (cortisol and alpha-amylase) were measured using the enzyme-linked immunosorbent assay method. Electrophysiological assessment of attention and stress was performed using electroencephalography. Neuropsychological assessments for the evaluation of mental health, mental fatigue, sustained attention, and reaction time were conducted using paced auditory serial addition test. All tests were administered before and after the interventions. The findings revealed that the salivary cortisol and alpha-amylase significantly reduced after playing the game. There were significantly higher levels of attention after playing the game. Mental health and sustained attention significantly increased after game playing. It can conclude that puzzle-style computer games can strengthen and empower the perceptual-cognitive system and suppress the stress system of players. Therefore, they can be used purposefully as a positive cognitive therapy approach.
Open Access
FPGA-based implementation of an underwater quantum key distribution system with BB84 protocol
(IEEE, 2023-08) Kebapçı, B.; Levent, V. E.; Ergin, S.; Mutlu, Görkem; Bağlıca, İbrahim; Tosun, A.; Paglierani, P.; Pelekanakis, K.; Petroccia, R.; Alves, J.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Bağlıca, İbrahim
As threats in the maritime domain diversify, securing data transmission becomes critical for underwater wireless networks designed for the surveillance of critical infrastructure and maritime border protection. This has sparked interest in underwater Quantum Key Distribution (QKD). In this paper, we present an FPGA-based real-time implementation of an underwater QKD system based on the BB84 protocol. The QKD unit is built on a hybrid computation system consisting of an FPGA and an on-board computer (OBC) interfaced with optical front-ends. A real-time photon counting module is implemented on FPGA. The transmitter and receiver units are powered with external UPS and all system parameters can be monitored from the connected computers. The system is equipped with a visible laser and an alignment indicator to validate successful manual alignment. Secure key distribution at a rate of 100 qubits per second was successfully tested over a link distance of 7 meters.
Open Access
Free space optical communication: An enabling backhaul technology for 6G non-terrestrial networks
(MDPI, 2023-11) Elamassie, Mohammed; Uysal, Murat; Electrical & Electronics Engineering; ELAMASSIE, Mohammed; UYSAL, Murat
The deployment of non-terrestrial networks (NTNs) is envisioned to achieve global coverage for 6G and beyond. In addition to space nodes, aerial NTN nodes such as high-altitude platform stations (HAPSs) and rotary-wing unmanned aerial vehicles (UAVs) could be deployed, based on the intended coverage and operational altitude requirements. NTN nodes have the potential to support both wireless access and backhauling. While the onboard base station provides wireless access for the end users, the backhauling link connects the airborne/space-borne base station to the core network. With its high data transmission capability comparable to fiber optics and its ability to operate in the interference-free optical spectrum, free space optical (FSO) communication is ideally suited to backhauling requirements in NTNs. In this paper, we present a comprehensive tutorial on airborne FSO backhauling. We first delve into the fundamentals of FSO signal transmission and discuss aspects such as geometrical loss, atmospheric attenuation, turbulence-induced fading, and pointing errors, all of which are critical for determining received signal levels and related link budget calculations. Then, we discuss the requirements of airborne backhaul system architectures, based on use cases. While single-layer backhaul systems are sufficient for providing coverage in rural areas, multi-layer designs are typically required to establish connectivity in urban areas, where line of sight (LoS) links are harder to maintain. We review physical layer design principles for FSO-based airborne links, discussing both intensity modulation/direct detection (IM/DD) and coherent modulation/coherent demodulation (CM/CD). Another critical design criteria for airborne backhauling is self-sustainability, which is further discussed in our paper. We conclude the paper by discussing current challenges and future research directions. In this context, we discuss reconfigurable intelligent surfaces (RIS) and spatial division multiplexing (SDM), for improved performance and an extended transmission range. We emphasize the importance of advanced handover techniques and scalability issues for practical implementation. We also highlight the growing role of artificial intelligence/machine learning (AI/ML) and their potential applications in the design and optimization of future FSO-based NTNs.
Open Access
HM-net: A regression network for object center detection and tracking on wide area motion imagery
(IEEE, 2022) Motorcu, Hakkı; Ateş, H. F.; Uğurdağ, Hasan Fatih; Güntürk, B. K.; Electrical & Electronics Engineering; UĞURDAĞ, Hasan Fatih; Motorcu, Hakkı
Wide Area Motion Imagery (WAMI) yields high resolution images with a large number of extremely small objects. Target objects have large spatial displacements throughout consecutive frames. This nature of WAMI images makes object tracking and detection challenging. In this paper, we present our deep neural network-based combined object detection and tracking model, namely, Heat Map Network (HM-Net). HM-Net is significantly faster than state-of-the-art frame differencing and background subtraction-based methods, without compromising detection and tracking performances. HM-Net follows object center-based joint detection and tracking paradigm. Simple heat map-based predictions support unlimited number of simultaneous detections. The proposed method uses two consecutive frames and the object detection heat map obtained from the previous frame as input, which helps HM-Net monitor spatio-temporal changes between frames and keep track of previously predicted objects. Although reuse of prior object detection heat map acts as a vital feedback-based memory element, it can lead to unintended surge of false positive detections. To increase robustness of the method against false positives and to eliminate low confidence detections, HM-Net employs novel feedback filters and advanced data augmentations. HM-Net outperforms state-of-the-art WAMI moving object detection and tracking methods on WPAFB dataset with its 96.2% F1 and 94.4% mAP detection scores, while achieving 61.8 % mAP tracking score on the same dataset. This performance corresponds to an improvement of 2.1% for F1, 6.1% for mAP scores on detection, and 9.5% for mAP score on tracking over state-of-the-art.
Open Access
Hybrid RF/VLC systems: A comprehensive survey on network topologies, performance analyses, applications, and future directions
(IEEE, 2021) Abuella, H.; Elamassie, Mohammed; Uysal, Murat; Xu, Z.; Serpedin, E.; Qaraqe, K. A.; Ekin, S.; Electrical & Electronics Engineering; ELAMASSIE, Mohammed; UYSAL, Murat
Wireless communications refer to data transmissions in unguided propagation media through the use of wireless carriers such as radio frequency (RF) and visible light (VL) waves. The rising demand for high data rates, especially, in indoor scenarios, overloads conventional RF technologies. Therefore, technologies such as millimeter waves (mmWave) and cognitive radios have been adopted as possible solutions to overcome the spectrum scarcity and capacity limitations of the conventional RF systems. In parallel, visible light communication (VLC) has been proposed as an alternative solution, where a light source is used for both illumination and data transmission. In comparison to RF links, VLC links present a very high bandwidth that allows much higher data rates. VLC exhibits also immunity to interference from electromagnetic sources, has unlicensed channels, is a very low power consumption system, and has no health hazard. VLC is appealing for a wide range of applications including reliable communications with low latency such as vehicle safety communication. Despite the major advantages of VLC technology and a variety of its applications, its use has been hampered by its cons such as its dependence on a line of sight connectivity. Recently, hybrid RF/VLC systems were proposed to take advantage of the high capacity of VLC links and better connectivity of RF links. Thus, hybrid RF/VLC systems are envisioned as a key enabler to improve the user rates and mobility on one hand and to optimize the capacity, interference and power consumption of the overall network on the other hand. This paper seeks to provide a detailed survey of hybrid RF/VLC systems. This paper represents an overview of the current developments in the hybrid RF/VLC systems, their benefits and limitations for both newcomers and expert researchers.
Open Access
Model predictive control of a PUC5-based dual-output electric vehicle battery charger
(MDPI, 2023-10) Makhamreh, Hamza; Kanzari, M.; Trabelsi, M.; Electrical & Electronics Engineering; MAKHAMREH, Hamza Ahmed Mousa
In this study, a model predictive control (MPC) technique is applied to a packed-u-cell (PUC)-based dual-output bidirectional electric vehicle (EV) battery charger. The investigated topology is a 5-level PUC-based power factor correction (PFC) rectifier allowing the generation of two levels of DC output voltages. The optimization of the MPC cost function is performed by reducing the errors on the capacitors’ voltages (DC output voltages) and the grid (input) current. Moreover, the desired capacitors’ voltages and peak value of the input current are considered within the designed cost function to normalize the errors. In addition, an external PI controller is used to generate the amplitude of the grid current reference based on the computed errors on the capacitors’ voltages. The presented simulation and experimental results recorded using a 1 kW laboratory prototype demonstrate the high performance of the proposed approach in rectifying the AC source at different levels (dual rectifier), while drawing a sinusoidal current from the grid with low THD (around 4%) and ensuring a unity power factor operation.
Open Access
A multioctave 8 GHz-40 GHz receiver for radio astronomy
(IEEE, 2023-04) Kooi, J. W.; Soriano, M.; Bowen, j.; Abdulla, Z.; Samoska, L.; Fung, A. K.; Manthena, R.; Hoppe, D.; Javadi, H.; Crawford, T.; Hayton, D. J.; Malo-Gómez, I.; Gallego-Puyol, J. D.; Akgiray, Ahmed Halid; Gabritchidze, B.; Cleary, K. A.; Jacobs, C.; Lazio, J.; Electrical & Electronics Engineering; AKGİRAY, Ahmed Halid
Accurate measurement of angular positions on the sky requires a well-defined system of reference, something that in practice is realized by the International Celestial Reference Frame (ICRF) with observations of distant (typical redshift similar to 1) Active Galactic Nuclei (AGN). At such great distances a subset of these objects exhibit as little as 10-50 mu as/year observed parallax or proper motion, thus giving the frame excellent spatial and temporal stability. Until fairly recently the majority of AGN centered imaging was accomplished in the S (2.3 GHz) and X (8.4 GHz) radio frequency bands, however S-band observations for reasons such as sensitivity "plateauing", increased source structure (jets), and radio frequency interference (RFI) have become less productive. Following spacecraft telemetry moves to higher frequencies and a desire to strengthen JPL's leadership in defining the next-generation of celestial reference frames has motivated the development of a "Quad-band" prototype receiver that operates in X, Ku, K, and Ka band in both right hand (RCP) and left hand (LCP) circular polarization. The goal of this receiver is to achieve less than a 20 % increase in noise over the Jansky Very Large Array (JVLA, NRAO) performance specification, which in such a wide bandwidth represents a revolutionary capability. To evaluate the various technical developments of the 8 GHz-40 GHz receiver the feedhorn optical beam was designed to interface to the US based Very Long Baseline Array (VLBA). The receiver's intermediate frequency (IF) spans 4 GHz-8 GHz, giving rise to up to eight 4 GHz IF channels for a fully populated instrument. This paper outlines the technical development of a 21/2 octave wide (8 GHz-40 GHz) X-Ka band prototype receiver, fulfilling a need for super broadband technology within the VLBI network. An important additional benefit of the wideband receiver approach is its simplicity and low cost of operation.
Open Access
Optimal resource allocation and interference management for multi-user uplink light communication systems with angular diversity technology
(IEEE, 2020) Eldeeb, Hossıen Badr; Hosney, M.; Elsayed, H. M.; Badr, R. I.; Uysal, Murat; Selmy, H. A. I.; Electrical & Electronics Engineering; UYSAL, Murat; ELDEEB, Hossien Badr Hossien
Light communication (LC) technology has been regarded as a promising candidate for future indoor wireless networks by providing safe, power-efficient, and high data rate communications needed for tomorrow's applications. Both visible light (VL) and infrared (IR) wavelengths can be utilized to design LC systems. It is often proposed that VL can be used to offload downlink traffic while near-IR is typically used in the uplink. In this paper, the uplink multi-user LC system is considered where the system performance is degraded by both inter-symbol interference (ISI) resulting from multipath reflections and inter-user interference (IUI) coming from neighboring users. To mitigate these limitations, an optimal fair resource allocation (OFRA) scheme is proposed which aims to improve the fairness among the users in terms of their received signal to interference plus noise ratios (SINRs) by implementing the angle diversity technology. Precisely, by assigning an ON/OFF state for each LED of the angle diversity transmitter (ADT), used by each user, the IUI can be significantly reduced. Also, the angle diversity receiver (ADR) is used to effectively mitigate the effects of ISI. The allocation matrix which achieves the highest fairness between different users is obtained for different scenarios of user distribution. Toward this, the exhaustive search (ES) method is used to obtain the optimal solution for the optimization problem under consideration. However, to reduce the time complexity of ES method, a quasi-optimal solution called sub-optimal fair resource allocation scheme SFRA is proposed. The sub-optimal solution is based on the genetic algorithm (GA) scheme. The simulation results reveal that both the OFRA and SFRA achieve almost the same performance. Moreover, the simulation results indicate the superior performance of the proposed OFRA scheme over the conventional single transmitter (ST) one.
Open Access
Theoretical modeling of viscosity monitoring with vibrating resonance energy transfer for point-of-care and environmental monitoring applications
(MDPI, 2019-01-01) Memişoğlu, G.; Gülbahar, Burhan; Zubia, J.; Villatoro, J.; Electrical & Electronics Engineering; GÜLBAHAR, Burhan Cahit
Forster resonance energy transfer (FRET) between two molecules in nanoscale distances is utilized in significant number of applications including biological and chemical applications, monitoring cellular activities, sensors, wireless communications and recently in nanoscale microfluidic radar design denoted by the vibrating FRET (VFRET) exploiting hybrid resonating graphene membrane and FRET design. In this article, a low hardware complexity and novel microfluidic viscosity monitoring system architecture is presented by exploiting VFRET in a novel microfluidic system design. The donor molecules in a microfluidic channel are acoustically vibrated resulting in VFRET in the case of nearby acceptor molecules detected with their periodic optical emission signals. VFRET does not require complicated hardware by directly utilizing molecular interactions detected with the conventional photodetectors. The proposed viscosity measurement system design is theoretically modeled and numerically simulated while the experimental challenges are discussed. It promises point-of-care and environmental monitoring applications including viscosity characterization of blood or polluted water.
Open Access
Visible light communication for connected vehicles: How to achieve the omnidirectional coverage?
(IEEE, 2021) Eldeeb, Hossıen Badr; Sait, S. M.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; ELDEEB, Hossien Badr Hossien
Visible light communication (VLC) is based on the idea of modulating the light intensity of LEDs to transmit information and enables the dual use of exterior automotive and road side infrastructure lighting for both illumination and communication purposes. To position VLC as a strong candidate for vehicular connectivity, it is essential to realize multi-directional reception in various deployment scenarios supporting both vehicle-to-vehicle (V2V) and infrastructure-to-vehicle (I2V) links. In this paper, we investigate the performance of a vehicular VLC system in different road types (i.e., multi-lane, curved roads), intersections (i.e., T-shaped, Y-shaped intersections) and traffic scenarios (i.e., cruising in the same or different lanes, lane change etc.). We conduct a channel modeling study based on non-sequential ray tracing to quantify the capability of receiving signals in different cases. Our results reveal that deployment of nine photodetectors with carefully determined locations on the vehicle is enough to create the required quasi-omni-directional coverage for both V2V connectivity (in front and back directions) and I2V connectivity.

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