Elektrik Elektronik Mühendisliği Bölümü,Bildiri & Sunum Koleksiyonu

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https://hdl.handle.net/11492/3539

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High attenuation lumped element band-stop filter design using resonator tuning method
(Institute of Electrical and Electronics Engineers Inc., 2022) Yıldon, Sabahattin Doruk; Kaygısız, Cemile Tuğçe; Tekbaş, Mustafa; Erden, Emre; Topaloğlu, Serkan
This paper presents a new design method for the high attenuation of a lumped element band-stop filter. The designed 960 - 1215 MHz band-stop filter is a structure that passes below 750 MHz and above 1500 MHz and provides an attenuation value below -50dB. This 7th order modified Cheby-shev topology band-stop filter designed with lumped elements has been manipulated to provide a -50 dB attenuation value by manipulating the Q factor values provided by the resonance structures. The synthesis and development processes of the band-stop filter are mentioned, respectively. The design was created in the AWR Design Environment and simulated with ideal and vendor components. PCB was designed and implemented using the Altium Design Software. PCB design was manufactured. S-parameter measurements of the band-stop filter were taken and recorded.
Parameter estimation of photovoltaic system using marine predators optimization algorithm-based multilayer perceptron
(Institute of Electrical and Electronics Engineers Inc., 2022) Çolak, Medine; Balcı, Selami
Solar irradiation data is an essential input for solar-thermal and photovoltaic systems. In this case, the coherence parameter estimation is a fundamental level in solar energy applications. For this purpose, a PV system has been modeled by the parametric solver of ANSYS-Electronics software and a data set has been created for the output voltage value depending on different input variables. In this paper, marine predators' algorithm is integrated to the multilayer perceptron algorithm in order to estimate the parameter. In the estimation level, air temperature, thermal coefficient and diffuse horizontal solar radiation parameters are evaluated in 2-tupled and 3-tupled input systems. In addition, the accuracy of the hybrid forecasting model developed is also tested on the basis of the hyperbolic tangent, sinus and sigmoid activation functions employed in the multilayer perceptron algorithm. Estimation results show that marine predators-based multilayer perceptron model is appropriate to parameter estimation, efficiently.
GPS bozucular için bütünleşik l-bant güç yükselticisi
(Institute of Electrical and Electronics Engineers Inc., 2022) Erden, Emre; Tekbaş, Mustafa; Burak Boz, Ogulcan; Topaloğlu, Serkan
This paper includes the analysis, design and implementation of Power Amplifiers (PA) operating in the specified frequency ranges (L1, L2, L5) in the L Band. This PA provides 18 W output power with 58% efficiency. The PA consist three different amplifier stage. GaN-on-SiC transistor is used in PA. The focus of the realized structure is efficiency and linearity. These requirements have been achieved with the choice of transistor technology, impedance matching circuit design and bias point selection. With this design, a Power Amplifier that can be used in signal jammers or amplifier units operating in the L band range has been produced.
Mikroşerit anten yapısı kullanılarak ölçülen deri dokusuna ait uzak alan ve yakın alan deǧerlerinin kıyaslanması
(Institute of Electrical and Electronics Engineers Inc., 2022) Toprak, Rabia; Gültekin, Seyfettin Sinan; Uzer, Dilek
Pathology science has an important place in the medical field. Its importance is increasing day by day because it evaluates the information about diseases at the cellular level. The reports prepared from the tissue samples examined by the pathologists contain very important information for both the patient and the doctor. This information may include the level of the disease and the mode of treatment. Therefore, the time to reach the pathological reports is important. Microstrip patch antennas are used for various purposes in the biomedical field. In this study, the far and near field outputs of the evaluations of the pathological tissue samples were tested with the microstrip patch antenna structure. For this, a microstrip patch antenna with an operating frequency of 2.45 GHz was used. Pathological tissue samples were modeled in the free-space measurement technique created using the antenna structure. The electric field and scattering parameter values obtained as a result of the simulations using the Ansys HFSS program were evaluated for the near and far field. When the evaluation results are examined, it has been shown that near field measurements for electric field data and far field measurements for scattering parameter data are more efficient.
Performance analysis of a permanent magnet synchronous generator with parametric solution software
(Institute of Electrical and Electronics Engineers Inc., 2022) Balcı, Selami; Çolak, Medine
The popularity of permanent magnet synchronous generator (PMSG) has increased in recent years. Small and medium-sized wind generators can be found in the smart grid structure, and synchronous generators without gearbox are used at different wind speeds thanks to their connections with power electronic circuits in grid integration. In this study, simulation studies are carried out for a small power scale PMSG with finite element analysis (FEA) software with different wind speed and design parameters. Thus, the performance analyzes of the generator depending on the number of stator winding turns, core material and load values are presented with graphic and numerical data. It has been tried to draw attention to the importance of parametric solver in generator performance analysis and the usefulness of the results obtained for researchers.
Design optimization of multilayer microwave filter using differential evolution algorithm
(IEEE, 2022) Toktaş, Abdurrahim; Üstün, Deniz
Three types of multilayer microwave filter (MMF) which are low-pass (LP), high-pass (HP) and band-pass (BP) are designed through a frequency-dependent material using Pareto-based multi-objective differential evolution (DE) (MODE) algorithm. To this end, a dual-objective electromagnetic (EM) model taking into account oblique incident wave angle with transverse electric (TE) or transverse magnetic (TM) polarization is constructed, which is based on total reflection (TR) for the passing and stopping bands. The global optimal designs (GODs) are selected from the Pareto optimal designs (PODs) by considering the trade-off among the objective values. The frequency and angular behavior of the MMFs are comparatively studied. The designed MMF are near ideal characteristic thanks to MODE having effective and powerful multi-objective strategy.
A new Pi-based chaotic map for ımage encryption
(Institute of Electrical and Electronics Engineers Inc., 2021) Erkan, Uǧur; Toktaş, Abdurrahim; Toktas, Feyza
Novel chaotic map (CM) based on pi number socalled Pi-map is introduced for image encryption scheme (ImES). The chaotic behavior of the Pi-map is appreciated with respect to Lyapunov Exponent (LE) and bifurcation graphs. The LE which is stable and highest is also compared those reported elsewhere. The image encryption performance of Pi-map is corroborated on a simple ImES consisting of only two operations which are permutation and diffusion. The ImES with Pi-map is crypto-studied through various analysis and, they are even crosschecked with the others in the literature. It is shown that ImES is eminent and reliable thanks to the capability of the Pi-map regarding randomness and complexness.
Coreloss Estimation via Long Short-Term Memory Model (LSTM) of Dry-Type Transformer based on FEA
(Institute of Electrical and Electronics Engineers Inc., 2021) Kül, Seda; Yıldız, Berat; Tamyürek, Bünyamin; İskender, İres
Accurate estimation of losses is very important in transformer designs for energy systems. Therefore, in this study, a long short-term memory model (LSTM) was performed to predict the core loss of three-phase dry-type transformers based on Finite Element Analysis (FEA) analysis. Since, in ordinary multilayer networks, learning problems occur when the gradient value gets too small during backpropagation. LSTM, on the other hand, can store information better thanks to its extra layers that communicate. Thus, the learning process takes place more efficiently. The analysis and estimation processes were performed using a primary number of turns, excitation voltage, and three different cross-section area parameters. 486 data randomly selected from 506 data obtained by ANSYS/MAXWELL in the training of the LSTM model were used. The remaining 20 data were used in the testing process to measure system performance. The error obtained by the validation test is 0.15. It is very close to the simulated value, thus LSTM can be used as a reliable estimation method during the design stage.
Triangular aperture UWB antenna with dual band-notched characteristic for WLAN bands
(Institute of Electrical and Electronics Engineers Inc., 2021) Toktaş, Abdurrahim
A compact ultra-wideband (UWB) patch antenna with dual band-notched characteristic is designed for 2.4 GHz and 5 GHz WLAN bands. First an UWB antenna with size of 15.23×35.02 mm2 is designed, operating over 2.4-11.8 GHz. Then the bands are notched through a step-by-step optimization process. The UWB antenna is optimally achieved by loading triangular aperture between the patch and ground. The 2.4 GHz and 5 GHz bands are respectively notched by adding an inverted U-shaped slit on the patch and two C-shaped strips over the ground plane. The design procedure of the band-notched antenna is expressed by verifying through the return loss. Moreover, the notching mechanism and radiation performance of the antenna are studied with regard to surface current distribution, 2D and 3D radiation patterns and peak gain. The results demonstrate that the proposed antenna is applicable for UWB operation as well as has dual band-notched characteristic at the frequency range of 2.2-2.8 GHz and 4.5-6.8 GHz.
A novel euler chaotic map for image encryption
(Institute of Electrical and Electronics Engineers Inc., 2021) Erkan, Uğur; Toktaş, Abdurrahim; Toktaş, Feyza
A novel chaotic map based on Euler number namely Euler Map (EMAP) is suggested for image encryption algorithms (IEAs). The chaotic behavior of EMAP is appreciated with bifurcation analysis and Lyapunov Exponent (LE). The LE is the best due to the ultimate and most stable characteristic in case compared with the literature. A two-stage IEA, permutation and diffusion, is used to demonstrate the successful performance of EMAP, and this is how the success of EMAP is verified. The IEA with EMAP is examined in secure cryptanalyses and computational complexity. Some results are validated with the state of the arts. In the comparison, the suggested EMAP-based IEA stands out due to the diversity and complexity performance. It achieves a cropped image having minimum loss, a good operation time of 0.2297s and a low computational complexity. Therefore, the proposed EMAP can be applied to realistic systems.
Dual-element MIMO Inverted-F Antenna for Mobile Devices
(IEEE Computer Society, 2020) Toktaş, Abdurrahim; Üstün, Deniz
In this study, a dual-element inverted multiple input multiple output (MIMO) F antenna (IFA) operating at 2.4 GHz band is designed by means of computational electromagnetic for WLAN wireless devices. The shape of IFA element resembles two superimposed E-shaped strips. IFA element with a small size of 10 × 13mm2 operates at the frequency range of 2.28-2.62 GHz. They are orthogonally placed at the corners of a 50 × 100mm2 main ground board for reducing the mutual coupling, i.e. correlation between the two elements. The radiation and isolation performance of MIMOIFA is examined in regards to the radiation patterns, envelope correlation coefficient (ECC) and peak gain. The proposed MIMO-IFA shows quasi-omni-directional pattern, under 0.05 ECC and about 2.7 dBi peak gain at 2.4 GHz. Therefore, it is a better and cheap candidate for 2.4 GHz industrial scientific medical (ISM) band including WLAN as well as wireless mobile devices.
Dual-objective design of multilayer radar absorbing composite material using butterfly optimization algorithm
(IEEE Computer Society, 2020) Toktaş, Abdurrahim; Üstün, Deniz
A Multilayer Radar Absorbing Material (MRAM) based on composite is designed using a dual-objective optimization method butterfly optimization algorithm (BOA). The two objective functions regard Total Reflection (TR) involving sub-reflection at the inner layers and Total Thickness (TT). In order to make the MRA material more applicable for real applications; first, Mean Oblique Incidence (MOI) of TR in the range of 0-60 degree with polarizations TE/TM and then the average of MOI-TR in the range of 2-18 GHz is taken for achieving MOI-TRavg. The design variables, i.e. the thickness and material specimens for each layer from a material database including 21 composite specimens is optimally determined for synchronously minimizing the two objectives. Thus, a Global optimum MRAM (GMRAM) is picked out within the distributed candidate optimal solution set through Pareto optimality. Therefore, a five-layer GMRAM effectively absorbing at 7-18 GHz is successfully determined with the objectives of -10.85 dB MOI-TRavg and 4.2493 mm TT by considering the trade-off between the two objectives. The GMRAM is compared with a respective design in the literature to demonstrate the effectiveness of proposed optimization method. The TT is reduced as 66% by keeping the TR performance almost the same thanks to the effective and versatile dual-objective optimization with BOA.
Estimation of global solar radiation by using ANN and ANFIS
(Institute of Electrical and Electronics Engineers Inc., 2019) Alparslan, N.C.; Kayabaşı, Ahmet; Rüşen, Selmin Ener
Solar energy has the greatest potential among the energy sources available in the world and it is clean and universal energy source. The first parameter that should be determined carefully when planning systems based on solar energy is the solar radiation value. The solar radiation values obtained from ground observations can be estimated with various software models. Especially, estimation models designed using emerging computer technology have ease of use and accuracy. In this study, the well-known artificial intelligence techniques such as artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) are used to estimate solar radiation. The analysis of solar radiation requires complex, lengthy and time consuming procedures and artificial intelligence techniques such as ANN and ANFIS eliminate great effort and time. A system that measures atmospheric data such as light, temperature and humidity using sensors is designed and for this study, measurements were made for over a month. The atmospheric data obtained from the climatic conditions of the province of Karaman and the surface solar radiation values measured using the Pyranometer are utilized to construct these models. As a result of testing the constructed models, the ANFIS model is found to be more successful than ANN. © 2019 IEEE.
Comparison of real and mathematical model data of pv systems to monitor the performance with fuzzy logic
(Institute of Electrical and Electronics Engineers Inc., 2019) Alparslan, N.C.; Kayabaşı, Ahmet; Rüşen, Selmin Ener
Today, photovoltaic (PV) systems are widely used to produce electricity from the sun, which has the greatest potential among renewable energy sources. However, the mathematical correct modeling is very important to develop, plan and use under optimal conditions of green, long-lasting, high-efficiency and low-cost PV systems, which are alternatives to traditional energy generation methods. This project is based on the development of an autonomous system for the creation of a mathematical model of the electrical equivalent circuit of the prototype PV module and the instantaneously monitoring of the performance of this PV module. To test the mathematical model created in this project, the power values were obtained and compared for the reference PV module under laboratory conditions and the accuracy of the created model was tested. In this project, the warning mechanism has been developed in case of any problems with performance monitoring of the prototype PV module system installed by using fuzzy logic. The project aims to ensure that PV systems work in a long time with high efficiency and thus support our country's energy requirement. © 2019 IEEE.
Design of a dual polarized mmwave horn antenna using decoupled microstrip line feeder
(Institute of Electrical and Electronics Engineers Inc., 2020) Tekbaş, Mustafa; Toktaş, Abdurrahim; Çakır, G.
In this study, a dual polarized horn antenna (DPHA) with a novel feeding system was designed at W band for millimeter wave receivers. The DPHA consists of the printed circuit board (PCB feeding system and back side short cavity, which closes the rear of the wave guide and a pyramid horn in the direction of radiation. The PCB feeding system has two orthogonally positioned microstrip line feeder elements with 50Ohm microstrip transmission line (MTL) and symmetrical square patches. There is enough space in DPHA for additional electronic circuits following the feeding system, such as LNA and mixer. Moreover, various parasitic strip line structure such as monopole, T shape, Y shape, short circuit and neutralization line were then added between the square patches so as to further increase the isolation between the feeding ports. The best isolation level was thus achieved by using the monopole structure without resulting in a gain loss. The DPHA was therefore designed with higher than 20dBi gain and a level of 15dB isolation as dual polarization between 80GHz and 100GHz. The DPHA can be used in millimeter wave polarimetric imaging systems and similar applications. © 2020 IEEE.
Performance optimization of a front-end circuit for capacitance measurements using grey wolf algorithm
(Institute of Electrical and Electronics Engineers Inc., 2020) Demirtaş, M.; Kara, Muhammet Rojhat; Erişmiş, M.A.; Güneş, S.
This study aims to optimize certain performance parameters of an analog front-end circuit for capacitance measurement. The front-end circuit produces an output voltage in proportional to the measured capacitance. This output voltage should be demodulated by means of digital or analog demodulators to extract the capacitance information. In order to obtain an accurate and precise capacitance measurement, the front-end circuit's performance parameters must be optimized carefully. In this paper, a transimpedance amplifier consisting of an operational amplifier with a feedback resistor and a feedback capacitor is employed as the front-end topology. The transimpedance amplifier's gain, settling time and outputreferred total noise are the performance criteria which form a multi-parameter optimization problem. These performance criteria primarily depend on the values of the feedback resistor, feedback capacitor and operation frequency. Grey Wolf optimizer Algorithm is used to find these values optimally. To verify the algorithm's results, SPICE based simulations are carried out for two capacitance measurements. © 2020 IEEE.
Determination of cardiovascular occlusion with microstrip antennas
(Institute of Electrical and Electronics Engineers Inc., 2020) Uyanık, H.; Uzer, D.; Top, Rabia; Gultekin, S.S.
In this study, it is aimed to detect occlusion in the cardiac vessels with two different microstrip antennas. Occlusions located in different locations and sizes in the vessel are simulated using ANSYS HFSS and detected by evaluating the Scattering parameters and Electric field values. Antennas in Circular and Seljuk star geometries are designed on Jean (Denim) substrate that allow usage in wearable applications. This study is a preliminary study of a research project and it is predicted that cardiovascular occlusions can be detected by using microstrip antennas in non-ionizing frequency band. Again, by evaluating the values taken, the location and percentage of the occlusion can be determined. © 2020 IEEE.
Design of quad-port circular MIMO antenna with isolation improved by shorting walls
(IEEE, 2019) Toktaş, Abdurrahim; Üstün, Deniz; Tekbaş, Mustafa
A compact co-located quad-port circular multiple-input-multiple-output (MIMO) antenna system operating at a wide frequency range of 3.0 - 5.0 GHz is designed in this study. The antenna system comprises a 20 mm radius circular patch composed of four co-located elements fed by 50 Ohm probe and a 50 x 50 mm(2) ground plane. To alleviate the mutual coupling among the antenna elements, the circular patch is split into four quadrants using two orthogonal shorting walls (SWs). In order to further improve the impedance matching, two circular slots are etched on the edge of the elements. The mutual coupling reducing performance of the SW is examined through the surface current and E-field distributions. The performance analysis of the MIMO system, regarding the radiation patterns, envelope-correlation-coefficient (ECC) and peak gain is thoroughly investigated. The antenna system is eligible for especially the access points due to being compact and versatile.
CS-Based Radar Measurement of Silos Level
(IEEE, 2015) Yiğit, Enes; Işıker, H.; Toktaş, Abdurrahim; Tjuatja, S.
The amount of the grain in bulk silos is the most important issue in commercial care. Therefore many level measurement methods have been used to measure the level of solids in silos. Existing methods, however, are generally based on one-point measurement which makes the three dimensional (3D) level measurement impractical. Microwave radar based systems can be used to 3D perception but the multiple scatterings occurred from metallic walls of the silo, makes it impossible. In this study we present the preliminary results of our compressive sensing based reconstruction algorithm to enhance backscattering signals inside a grain silo. The method proposed here eliminates the effect of multiple scattering form silo wall and gives the accurate reading of the grain level. The effectiveness of the recommend CS-based reconstruction method, which will be able to extend to 3D level perception, was verified through a real data of bulk silo.
Classification of different forest types with machine learning algorithms
(Latvia Univ Life Sciences & Technologies, 2016) Sabancı, Kadir; Ünlersen, M. Fahri; Polat, Kemal; Treija, S; Skujeniece, S
In this study, forest type mapping data set taken from UCI (University of California, Irvine) machine learning repository database has been classified using different machine learning algorithms including Multilayer Perceptron, k-NN, J48, Naive Bayes, Bayes Net and KStar. In this dataset, there are 27 spectral values showing the type of three different forests (Sugi, Hinoki, mixed broadleaf). As the performance measure criteria, the classification accuracy has been used to evaluate the classifier algorithms and then to select the best method. The best classification rates have been obtained 90.43% with MLP, and 89.1013% with k-NN classifier (for k=5). As can be seen from the obtained results, the machine learning algorithms including MLP and k-NN classifier have obtained very promising results in the classification of forest type with 27 spectral features.

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