Elektrik Elektronik Mühendisliği Bölümü

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Citation Count: Akan, E.; Akagündüz, E.; Uslu, I. B. (2021). "A data collection system design for hand gestures", 2021 International Conference on INnovations in Intelligent SysTems and Applications, INISTA 2021 - Proceedings.
A data collection system design for hand gestures
(2021) Akan, E.; Akagündüz, E.; Uslu, I. B.
In this study, we aim at designing a smart glove, which consists of different inertial sensors and an EMG sensor and developing a human-machine interaction application by pre-processing and fusing these different sensory data. We also aim at providing solutions in cases where image processing-based approaches are inefficient. In the proposed smart glove, the quaternion-based orientation data to be produced by the magnetometer and gyroscope together, the acceleration data to be generated by the accelerometer, and the analog data generated by the EMG sensor are collected and then prepared for use by different applications. © 2021 IEEE.
Citation Count: Kaplan, Alper; Akagündüz, Erdem (2020). "A Hybrid Framework for Matching Printing Design Files to Product Photos", Balkan Journal of Electrical and Computer Engineering, Vol. 8, No. 2, pp. 170-180.
A Hybrid Framework for Matching Printing Design Files to Product Photos
(2020) Kaplan, Alper; Akagündüz, Erdem; 233834
We propose a real-time image matching framework, which is hybrid in the sense that it uses both hand-crafted features and deep features obtained from a well-tuned deep convolutional network. The matching problem, which we concentrate on, is specific to a certain application, that is, printing design to product photo matching. Printing designs are any kind of template image files, created using a design tool, thus are perfect image signals. However, photographs of a printed product suffer many unwanted effects, such as uncontrolled shooting angle, uncontrolled illumination, occlusions, printing deficiencies in color, camera noise, optic blur, et cetera. For this purpose, we create an image set that includes printing design and corresponding product photo pairs with collaboration of an actual printing facility. Using this image set, we benchmark various hand-crafted and deep features for matching performance and propose a framework in which deep learning is utilized with highest contribution, but without disabling real-time operation using an ordinary desktop computer.
Citation Count: İnan, Tolga; Narbaev, Timur; Hazır, Öncü (2022). "A Machine Learning Study to Enhance Project Cost Forecasting", IFAC-PapersOnLine, Vol. 55, No. 10, pp. 3286-3291.
A Machine Learning Study to Enhance Project Cost Forecasting
(elsevier, 2022) İnan, Tolga; Narbaev, Timur; Hazır, Öncü
In project management it is critical to obtain accurate cost forecasts using effective methods. This study presents a Machine Learning model based on Long-Short Term Memory to forecast the project cost. The model uses the seven-dimensional feature vector, including schedule and cost performance factors and their moving averages as a predictor. Based on the cost variation patterns from the training phase, we validate the model using three hundred experiments in the testing phase. Overall, the proposed model produces more accurate cost estimates when compared to the traditional Earned Value Management index-based model.
Citation Count: Mezaal, Yaqeen S.; Eyyuboglu, Halil Tanyer, "A New Narrow Band Dual-Mode Microstrip Slotted Patch Bandpass Filter Design Based on Fractal Geometry", 2012 7th International Conference On Computing and Convergence Technology (Iccct2012), pp. 1180-1184, (2012)
A New Narrow Band Dual-Mode Microstrip Slotted Patch Bandpass Filter Design Based On Fractal Geometry
(IEEE, 2012) Mezaal, Yaqeen S.; Eyyuboğlu, Halil T.; 7688
A narrowband, compact, and easily fabricated microstrip bandpass filter design is introduced in this paper as a candidate for use in modern wireless systems. The proposed filter design is based on the use of dual-mode (two pole) square slotted microstrip resonator. This microstrip bandpass filter has the advantages of possessing much narrower and sharper performance responses than those of the single mode resonator and conventional square patch filter. The proposed microstrip filter structure is fractally generated using Sierpinski fractal curve geometry applied to the conventional square microstrip patch. Filter structures resulting from the successive iterations in the fractal generation process show a considerably low insertion loss, and sharper response of about 1% fractional bandwidth as compared with the conventional microstrip square patch filter of 3% fractional bandwidth designed at the same frequency using the same substrate material. The performance of filter structures, based on dual-mode resonators up to the third iterations, has been evaluated using a full-wave based electromagnetic simulator Sonnet software package. Performance simulation results show that these filter structures offer narrower fractional bandwidth percentages as compared with other types of non- fractalized filter structures.
Citation Count: Preveze, B. (2018). "A Novel Analytical Method for Throughput Calculation of Wireless Ad-Hoc Networks Running Different Routing Algorithms ", International Journal of Research Studies in Electrical and Electronics Engineering, Vol.4, No.4, pp.1-10.
A Novel Analytical Method for Throughput Calculation of Wireless Ad-Hoc Networks Running Different Routing Algorithms
(2018) Preveze, Barbaros; 17573
Because of the increasing number of internet related applications, the role of total router transmission delay became much more important for the service quality. For this purpose, the tunneling techniques have been widely used especially for real time multimedia transmission to have less number of route constructions and to be able to forward each packet at each router without the need of reaching the upper OSI (Open Systems Interconnection) layers. But, in mobile networks, since the network experience with more changes in traffic conditions and node locations, tunnels will be reconstructed for many times and some extra delay will occur to reconstruct these tunnels. In this work, the place of the tunneling algorithm is taken by the well-known MPLS (Multi-Protocol Label Switching) protocol and for confirmation the throughput calculations are made by considering two different routing algorithms, one of which is AEABR algorithm proposed in [1] (shown in [2] that it improves the system throughput w.r.t Fastest path Routing algorithm [3] for various vehicular velocities), and the other one is Fastest Path routing algorithm [3]. In this work a novel analytical method for throughput calculation of wireless ad-hoc networks running aforementioned routing algorıthms is proposed including the effects of extra delay caused by extra Route Reconstructions (RRC).
Citation Count: Preveze, B. (2015). A novel cognitive method for throughput ımprovement of mobile multi-hop ad hoc networks. Wireless Personal Communications, 82(1), 229-243. http://dx.doi.org/10.1007/s11277-014-2205-1
A novel cognitive method for throughput improvement of mobile multi-hop ad hoc networks
(Springer, 2015) Preveze, Barbaros; 17573
We had previously defined a novel cognitive method for throughput improvement of IEEE 802.16j mobile multi-hop ad-hoc network which enables better management of the spectral access and buffer management of the nodes in the network. By this method we had minimized the packet loss ratio and improved the throughput of IEEE 802.16j network. In this study, a novel cognitive buffer management algorithm is proposed that arranges the packets stored in the buffers of the nodes in a probabilistic way and selects correct packet of the correct node to transmit first to provide fewer packet losses and also fewer average hop-counts for more throughputs. It is shown that the novel proposed buffer management algorithm provides about 19.45 % more throughput improvement (on average) with respect to the results evaluated by the buffer management algorithm used before (which was also shown to provide 12 % throughput improvement with respect to a First In First Out buffer management algorithm). All the results evaluated in this study are also confirmed by the results of analytical calculations, the results of the developed simulation program and the results evaluated in the literature.
Citation Count: Preveze, Barbaros (2020). "A Novel High Performance Routing Algorithm for Mobile Multi-hop Tunneling Networks", Wireless Personal Communications, Vol. 114, No. 1, pp. 1-27.
A Novel High Performance Routing Algorithm for Mobile Multi-hop Tunneling Networks
(2020) Preveze, Barbaros; 17573
By the increased number of mobile devices, the demand of high speed connection oriented tunneling networks also increases. But, in mobile tunneling networks, the full route will have to be reconstructed more frequently because of more frequent route failures, where the requirements for extra route reconstructions (RRC) will cause extra delay and a decreased system throughput. In this work, a novel routing algorithm, optimum path routing (OPR) is proposed to extend the route life time of mobile multi hop tunneling networks and to increase the system throughput. On the other hand, as the most recent works in the literature indicate that, one of the greatest challenges of tunneling networks is to provide the network flexibility by instant adaptation on changing network conditions to keep the delay at lowest levels even in case of high traffic loads or node failures. To solve the aforementioned flexibility problem of the tunneling networks, a novel algorithm applicable to all kinds of routing algorithms called "avoid congested nodes (ACN)" is proposed. The results show that, the OPR algorithm proposed to increase the route life has succeeded in decreasing the RRC delay by 84% and improving the throughput by 20.17% with respect to the Fastest Path routing algorithm in the literature. And the ACN algorithm, proposed to provide a rapid adaptation of the nodes to the changing traffic conditions, has also succeeded in carrying back the throughput of the network with traffic load from 75.5% of its best performance evaluated with no traffic to its 94%.
Citation Count: Preveze, Barbaros (2019). "A Novel Method For Performance Improvement of Slow Start Congestion Control Method In Packet Switched Networks", Uludağ Üniversitesi Mühendislik Fakültesi Dergisi, Vol. 24, No. 3, pp. 451-467.
A Novel Method For Performance Improvement of Slow Start Congestion Control Method In Packet Switched Networks
(2019) Preveze, Barbaros; 17573
By the introduction of all IP networks with the smart homes, smart phones, car multimedia systems wearable technologies and IP TV’s, the number of internet related devices and the number of applications have increased. This has generated an increased quantity of bandwidth usage in packet switching networks. Therefore, the betterment of the bandwidth usage and the system performance has become more significant. Thus, there is a large number of works in the literature attempting to improve the network performance. For this purpose, generally the modifications of used methods in the network structures are preferred, rather than making major hardware based modifications requiring more financial support. In this work, a novel method called Return Back to threshold (RBT) is proposed to be applied to packet switched networks for a better congestion control.
Citation Count: Şener, G. (2017). A novel method to solve 2nd order neumann type boundary value problems in electrostatics. Applied Computational Electromagnetics Society Journal, 32(4), 289-294.
A novel method to solve 2nd order neumann type boundary value problems in electrostatics
(Applied Computational Electromagnetics Soc., 2017) Şener, Göker; 17740
In this paper, the numerical method of nonpolynomial spline approximation is used to solve 2nd order Neumann type boundary value problems (bvp's) in electrostatics. This new approach provides more accurate results than the polynomial approximations and the spectral methods. The literature contains very little on the solution of Neumann type bvp's because of the fact that a unique solution does not exist for all problems. In electrostatics, Neumann type bvp's are encountered for finding the electrostatic potential inside closed surfaces where the normal derivative of the electric potential is specified everywhere on the surface. Two examples are presented to prove the accuracy of the proposed method. In these examples, the governing differential equation is solved to find the electrostatic potential inside a region bounded by conductors that are maintained at constant voltages. The results are compared with the analytic solutions.
Citation Count: Preveze, B. (2023). "A Novel Solution for Network Flexibility Problem in Mobile Multi-hop Tunneling Networks", Wireless Personal Communications, Vol.129, No.2, pp. 1049-1068.
A Novel Solution for Network Flexibility Problem in Mobile Multi-hop Tunneling Networks
(2023) Preveze, Barbaros; 17573
Since the network throughput performance is limited by the available technology limits, there are too many attempts in the literature to improve the throughput performance of the network by modifying the routing algorithms currently in use. Although application of the tunneling on IP networks provides reserved paths for the higher priority packet streams and succeeds in providing faster communication performances, it is also determined in the literature that, the greatest up to date problem of tunneling networks is the flexibility problem, which is defined as the problem of difficulty to have minimal delay and highest throughput when congestions or node failures occur and the throughput decreases due to high traffic loads on the network. sIn this work, a high performance solution, called LB-ACN (Location Based- Avoid Congested Node) is proposed to solve this flexibility problem and to compensate the increased delay which came up due to the high traffic load and also due to inflexible tunneling network structure, considering the locations of the nodes in addition to their traffic loads. And it is shown that, it is succeeded to carry the throughput of the highly traffic loaded network back to 48.6 Mbps from 36.9 Mbps by about 31.7% performance improvement for which we could improve it from 36.9 Mbps up to 45.9 Mbps by 24.3% using the proposed ACN (Avoid Congested Node) algorithm in our previous work. As a result, we have succeeded in having about 7.4% more improvement on throughput performance in comparison with the previously proposed ACN algorithm.
Citation Count: Demirkutlu, E.; İskender, İ. "A Novel Transformerless Single-Phase Three-Level Buck-Boost Inverter", 2023 IEEE Applied Power Electronics Conference And Exposition, APEC, Proceedings, pp. 114-120, 2023.
A Novel Transformerless Single-Phase Three-Level Buck-Boost Inverter
(2023) Demirkutlu, Eyyup; Iskender, Ires; 133746
This paper proposes a novel transformerless, single-phase, three-level, buck-boost inverter. The proposed inverter can suppress the leakage current drawn from the input power source and provide a long-lasting solution for applications with a wide range and unregulated input voltage. Unlike similar topologies, in the proposed inverter there is no need to have a mid-point of DC sources or DC bus capacitors at the input side of the inverter. A single-phase, three-level, buck-boost inverter for realizing the power stage with 110-Vrms output AC voltage and a range of 100V-200V input DC voltage is investigated in this study. The proposed topology has been proven through theory, computer simulations, and experimental studies with SiC MOSFETs-based prototype of a 300-VA power supply. Theory, computer simulation, and experimental results are all correlated.
Citation Count: Toreyin, Behcet Ugur; Aktas, Hakan; Sever, Refik, "A Two Stage Template Matching Algorithm and Its Implementation on FPGA", 23nd Signal Processing and Communications Applications Conference (SIU), pp. 2214-2217, (2015).
A Two Stage Template Matching Algorithm and Its Implementation on FPGA
(IEEE, 2015) Aktaş, Hakan; Sever, Refik; Töreyin, Behçet Uğur; 19325
In this paper, to decrease the computational cost and number of cycles in Template Matching Algorithm, a novel two-stage algorithm is proposed. The Sum of Absolute Differences method is used for matching. The proposed algorithm is implemented on Field-Programmable-Gate-Array (FPGA). The algorithm is accelerated with the effective usage of Block RAMs distributed on FPGA. Thus, the proposed algorithm became fast enough for real time object tracking applications on UAVs.
Citation Count: Salmanogli, Ahmad; Gecim, H. S. (2022). "Accurate method to calculate noise figure in a low noise amplifier: Quantum theory analysis", Microelectronics Journal, Vol.128.
Accurate method to calculate noise figure in a low noise amplifier: Quantum theory analysis
(2022) Salmanogli, Ahmad; Gecim, H. Selcuk; 182579
In this study, a low-noise amplifier is quantum-mechanically analyzed to study the behavior of the noise figure. The analysis view has been changed from classic to quantum, because using quantum theory produces some degrees of freedom, which may be ignored when a circuit is analyzed using classical theory. For this purpose, the Lagrangian is initially derived by considering the related nonlinearity of the transistor, and then using the Legendre transformation and canonical quantization procedure, the quantum Hamiltonian is derived. As an interesting point of this study, the low-noise amplifier is deliberately considered as two oscillators connecting to each other to share the photonic modes between them; accordingly, the voltage and current as measurable observations and the noise figure as a critical quantity in a low-noise amplifier are theoretically expressed in terms of the oscillator's mean photon number. The main goal of this work is to study quantities such as the noise figure in a sufficient detail using quantum theory. In addition, as an advantage of this theory, one can control and manipulate the noise figure only by manipulation of the oscillator's mean photon number and coupling it between two oscillators. Finally, the circuit is classically designed and simulated to verify the derived results using quantum theory. The comparison results show that there is a partial consistency between the two approaches; as the frequency increases, the noise figure becomes minimized at a particular frequency.
Citation Count: Baykal, Y. (2022). "Adaptive optics correction of beam spread in biological tissues", Journal of Quantitative Spectroscopy and Radiative Transfer, Vol.283.
Adaptive optics correction of beam spread in biological tissues
(2022) Baykal, Yahya
Beam spread in turbulent biological tissues is examined when the tissue is excited with a collimated Gaussian laser beam. Adaptive optics correction is applied to the beam spread in the form of piston only (P Only), tilt only (T Only), piston+tilt (P+T), and the reduction in the beam spread is evaluated as compared to the no adaptive optics (No AO) corrected beam spread. No AO and adaptive optics corrected beam spread are expressed for various biological tissue types, against the variations in the strength coefficient of the refractive-index fluctuations, source size, small length-scale factor of turbulence, tissue length, fractal dimension, characteristic lengths of heterogeneity and the wavelength. For the examined tissue types of liver parenchyma (mouse), intestinal epithelium (mouse), upper dermis (human) and deep dermis (mouse), No AO beam spread and the adaptive optics corrected beam spread are found to increase as the strength coefficient of the refractive-index fluctuations, tissue length, fractal dimension, the characteristic lengths of heterogeneity increase, and to decrease as the source size, small length-scale factor, wavelength increase. Reduction ratio of P+T correction is almost the same for all the evaluated cases which is 74%.
Citation Count: Baykal, Yahya (2020). "Adaptive optics corrections of scintillations of Hermite-Gaussian modes in an oceanic medium", Applied Optics, Vol. 59, No. 16, pp. 4826-4832.
Adaptive optics corrections of scintillations of Hermite-Gaussian modes in an oceanic medium
(2020) Baykal, Yahya; 7812
Adaptive optics correction of the scintillation index is found when Hermite-Gaussian laser beams are used in oceanic turbulence. Adaptive optics filter functions are used to find how the tilt, focus, astigmatism, coma, and total correction will behave under high order mode excitation. Reduction of the oceanic scintillation under various oceanic turbulence and system parameters is examined under different high order modes. Also, the effects of the source size, wavelength, and link length on the total adaptive optics correction of Hermite-Gaussian modes in an oceanic medium are investigated for different modes. (C) 2020 Optical Society of America
Adaptive optics effect on performance of BPSK-SIM oceanic optical wireless communication systems with aperture averaging in weak turbulence
(2020) Gökçe, Muhsin Caner; Baykal, Yahya; Ata, Yalçın; 7812
Turbulence-induced wavefront deformations cause the irradiance of an optical signal to fluctuate resulting a in serious degradation in the bit-error-rate (BER) performance of optical wireless communication (OWC) system. Adaptive optics is an effective technique to compensate for the wavefront aberrations to reduce the fluctuations in the received intensity. In this paper, we investigate how the adaptive optics technique affects the BER performance of an oceanic OWC (OOWC) system employing binary phase shift keying-subcarrier intensity modulation (BPSK-SIM) and aperture averaging. To evaluate BER performance in weak oceanic turbulence, the required entities such as the received optical power captured by a circular aperture and the aperture averaged scintillation index measuring the fluctuations in the received irradiance are derived. The effect of adaptive optics correction of various wavefront aberrations (i.e., tilt, defocus, astigmatism and the coma) on the BER performance is illustrated and the performance of the adaptive optics-OOWC system is compared to that of a non-adaptive optics OOWC system by the metric defined. (C) 2020 Elsevier Ltd. All rights reserved.
Citation Count: Preveze, Barbaros; Safak, Aysel, "Alternative Enhancement of Associativity Based Routing (AEABR) for Mobile Networks", Vol. 32, pp. 67-+, (2010).
Alternative Enhancement of Associativity Based Routing (Aeabr) for Mobile Networks
(Springer, 2010) Preveze, Barbaros; Safak, Aysel; 17573
This study proposes an alternative enhancement for the Enhanced Associativity Based Routing (EABR) method which is a derivation of ABR (Associativity Based Routing) by relative speed and relative distance estimation using the received power strength (RPS) of the nodes. In this study, it is shown that EABR outperforms some other well known protocols. The performance of EABR is improved in terms of number of route reconstructions (RRC) and connected status percentage (CSP). Message overhead and bandwidth utilization is also investigated.
Citation Count: Najafi, Atabak; İskender, İ. (2021). "Amorf Çekirdekli Transformatörün Çoklu Fizik Yöntemiyle Elektromanyetik - Sıcaklık Analizi", Afyon Kocatepe Üniversitesi Fen ve Mühendislik Bilimleri Dergisi, Vol.21, No.5, pp.1086-1096.
Amorf Çekirdekli Transformatörün Çoklu Fizik Yöntemiyle Elektromanyetik - Sıcaklık Analizi
(2021) Najafi, Atabak; İskender, İres; 133746
Bu makalede, Amorf nüveli transformatörün sıcaklık analizini detaylı incelemek için, ısı transferi, akışkan akışı ve elektromanyetik analizlerini kapsayan çok disiplinli bir yaklaşım kullanılmıştır. Transformatörün bobini ve çekirdeğindeki güç kayıpları incelenip, sıcaklık ve akışkan akış analizleri elektromanyetik bir model ile birleştirilmiştir. Önerilen yöntem, Amorf çekirdekli gibi özel transformatörlerde, önceki noktasal sıcaklık bilgisine ya da sıcaklık Gradyan değerlerine ihtiyaç duymadan, sıcaklık değişimini detaylı olarak tahmin edebilmektedir. Teorik çalışma sonuçları uluslararası standartlara göre Dyn11, 34.5/0.4-kV, 630-kVA’lik amorf çekirdekli transformatör üzerine uygulanan deneysel çalışma sonuçlarıyla doğrulanmıştır. Teorik ve pratik çalışma sonuçlarının karşılaştırılması, sonuçların büyük bir uyum içinde olduğunu göstermekte olup, kullanılan yöntem genç mühendislere güç transformatörlerin sıcaklık analiz çalışmalarında faydalı bir araç oluşturmaktadır.
Citation Count: Uzun, E.; Akagunduz, E., "An Analysis On the Effect of Skip Connections in Fully Convolutional Networks for License Plate Localization [Tam Evrişimli Aǧlardaki Atlama Baǧlantilarinin Plaka Konumu Bulmaya Etkisi Üzerine Bir İnceleme]", 27th Signal Processing and Communications Applications Conference, Sıu 2019, (2019).
An Analysis On the Effect of Skip Connections in Fully Convolutional Networks for License Plate Localization [Tam Evrişimli Aǧlardaki Atlama Baǧlantilarinin Plaka Konumu Bulmaya Etkisi Üzerine Bir İnceleme]
(Institute of Electrical and Electronics Engineers Inc., 2019) Akagündüz, Erdem; Uzun, Engin; 233834
In this study, the effect of the skip connections, which are seen in fully convolutional networks, on object localization is analyzed. For this purpose, a local data set for plate detection is created. Experiments are carried out using this data set. Due to the small size of the image set, data augmentation method is used to overcome the danger of over-fitting. The learning rates of the first layers are frozen for analysis and finetuning is applied to only the last layer and deconvolution layers. The results obtained are compared with the results of other image sets. The results indicate the importance of the information provided by the skip connections on object localization.
Citation Count: Yükselen, Emir; İskender, I. (2022). "Analysis and Design of a Special Type Power Transformer Used in Solar Power Plants", International Journal of Renewable Energy Research, Vol.12, No.2, pp.667-673.
Analysis and Design of a Special Type Power Transformer Used in Solar Power Plants
(2022) Yükselen, Emir; İskender, Ires
Due to growing of greenhouse gas emissions and lack of the fossil sources, governments encouraged all scientists and utilities for looking to the alternative energy sources such as solar renewable energy which can help to reduce carbon dioxide emissions. In this respect, Photovoltaic (PV) power plants have become more important in recent years and renewable energy sources integrated into the power system are increasing day by day. Transformers are the main components of electrical grids and are widely used in renewable power plants to transfer the energy they produce to the grid. Accordingly, transformers are one of the most critical equipment of PV plants, and their safe operation and stability in the electrical network are important. This type of transformer is supplied from solar panels through inverters and needs to be customized to work with each system. In this type of transformer, the losses are higher than those for transformers used in electrical power systems supplied by sinusoidal voltage considering existence of different voltage and current harmonics content produced by the inverter. In this study, a special type of PV transformer was designed in accordance with the target performance criteria, taking into account the effects of harmonics, and keeping the transformer losses and temperature rise at a safe level. In this paper also the simulation results are compared with those of experiments test to verify the design procedures.

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