Mühendislik Fakültesi, Elektrik Elektronik Mühendisliği (İngilizce) Bölümü Koleksiyonu
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Öğe Hardware in the loop based design, development and verification of multi-agent system (MAS) based protection for a smart distribution network(2023) Shobole, Abdulfetah Abdela; Hocaoğlu, Mehmet Hakan; Baysal, Mustafa; Vadi, Mohammed; Abafogi, Motuma; Amireh, Yahia Khaleel Mustafa; Ahmed, Abdelrahman Mohamed Ismail; Khalid, HammadModern koruma röleleri, akıllı şebeke işleyişini optimize etmede temel bileşenler olarak hizmet eder. Birçok besleyici ve enerji kaynağını entegre etmek, çift yönlü enerji akışını etkili bir şekilde yönetmek için verimli bir strateji gerektirir. Mevcut modern koruma röleleri, arıza çözme işlemini etkili bir şekilde koordine etme konusunda sınırlamalarla karşı karşıyadır, bu nedenle uyarlanabilir bir koruma rölesine ihtihaç duyulmaktadır. Bu proje'nin temel amacı, çift yönlü enerji akışının karmaşık teknik zorluklarını ele almak için çoklu ajan sistemine (MAS) dayalı bir adaptif koruma rölesi formüle etmek, tasarlamak, geliştirmek ve doğrulamaktır. Geliştirilen röle ayrıca elektrik alt istasyonundaki kaynakların veya yüklerin eklenmesi veya çıkarılması nedeniyle ağ yapılandırma değişiklikleri için otomatik yeniden yapılandırma özelliğine sahiptir.Öğe Black body radiation problem with an infinite speed of light perspective and some consequences(Institute of Electrical and Electronics Engineers Inc., 2024) Yener, NamıkThe black body radiation problem is considered in view of the possibility of an infinite speed of light c brought up by the author in previous work. When c is infinite, the relation k = frac?c which is the result of Maxwell's equations for the Fourier transform of an electromagnetic wave excludes the possibility of the ultraviolet catastrophe for the black body radiation problem. This removes a necessity of discretization of energy. To demonstrate that under infinite speed of light and without the discretization of energy it is possible to model the photo-electric effect, the phenomenon of extraction of an electron from a metallic surface by an incident wave is considered. Magnetic sources which are found to accompany an infinite light speed are also accounted for in the field equations. Using the Fourier transform of the fields including the fields emitted by the extracted electron and the created magnetic charge, a Poynting vector computation is performed to enforce the power conservation principle. The equation relating the incident wave frequency, electron kinetic energy and the work function of the metal is obtained. As another effort to demonstrate the viability of a non-discretized energy approach when light speed is infinite, early quantum theory is visited and some non-causal and heuristic assumptions of the theory are attempted to be replaced by the findings of the proposed approach. Bohr's atomic model is the focus of the examination that may raise the question of whether a similar treatment can be applied to other quantization procedures of the relevant atomic spectrum theory such as for magnetic quantum numbers, spin quantum numbers, etc. when speed of light is infinite. © 2024 IEEE.Öğe A novel microstrip patch antenna design for mobile applications(IEEE Computer Society, 2014) Elmas, Volkan; Demircioğlu, Erdem; İmeci, TahaIn this study, a microstrip antenna operating at 1840 MHz is designed and simulation results are presented. Sonnet Suits 12.56 a powerful 3D EM simulator for antenna applications is utilized as the design software. The antenna air thickness is 170 mm and the gap between the antenna and floor is 3.05 mm. Cell size is regarded as 0.75 mm. The frequency of antenna is simulated in the frequency range of 1-3 GHz. S11, the back scattering parameter has the value of -15.5434 dB at the center frequency. The real value of the input impedance is 38.23716 Ohms and the imaginary value is 9.008487 Ohms. The resonance frequency has the gain value of 8.883196 dB.Öğe Electromagnetic charge density with a causal current density vector and infinite speed of light(Institute of Electrical and Electronics Engineers Inc., 2024) Yener, NamıkIn past work we have obtained necessary and sufficient conditions for the existence of an infinite speed of light c for reference frames in relative motion. These frames could house general linear or specific nonlinear systems and the characteristic for this result was a temporal discontinuity in the relative velocity of the motion of the frames. The search for the same infinite c effect in an electromagnetic system was affirmative provided that the current density vector in motion possessed a temporal discontinuity. The failure of the Lorenz condition was utilized to devise an approach that yielded this result. This property meant the failure of Maxwell's equations. For the Lorenz condition and the wave equations for the potentials are equivalent to Maxwell's equations. Also obtained was the side result of emergence of magnetic sources. The purpose of the present work is to show that in an electromagnetic system an infinite c is possible along with the advent of magnetic sources when the current density vector is simply causal, be it with or without a temporal discontinuity provided that the acceleration of the charge density is nonzero at the inception instant of the motion. We thus extend the previously determined infinite c result for the motion of a charge density with infinite initial acceleration to also include now the case of a motion with a nonzero but finite initial acceleration. With finite and infinite accelerations, we respectively have continuous and discontinuous current density vectors assuming the charge density function is not zero at t = 0. For the continuous case magnetic sources emerge unless the charge density function and the Green's functions for the scalar and vector potentials satisfy a specific condition. For the abruptly starting motion case there exists no restriction. However, for a stationary charge density as in a Hertz dipole (and hence for an arbitrary antenna) where a velocity function is not defined, the causal current density vector continuous at t = 0 will not support an infinite c. An exemplary computation is provided for when the current density vector is continuous using the Green's function for an infinite half space.Öğe A comparison on energy detector and CNN-based detector(IEEE, 2020) Tokgöz, Gamze Kirman; Tekbıyık, Kürşat; Kurt, Güneş Karabulut; Yarkan, SerhanIn today's wireless communication technology, users are classified and assigned to the spectrum by licensing method. There are two types of users in cognitive radio technology, licensed and unlicensed. While primary users use a fixed frequency band, secondary users can detect frequency gaps by different methods, enabling communication when primary users are not using it. With cognitive radio technology, it is aimed to meet the increasing user demands and to make communication faster as a result of using spectrum gaps more efficiently. In this study, energy detector and convolutional neural network (CNN) are compared and investigated which can be more efficient in spectrum sensing.Öğe An acoustic signal based language independent lip synchronization method and its implementation via extended LPC(IEEE, 2020) Cankurtaran, Halil Said; Boyacı, Ali; Yarkan, SerhanProcessing human speech with the use of digital technologies leads to several important fields of research. Speech-to-text and lip-syncing are among the instances of relevant prominent research areas. In this regard, audio-visualization of acoustic signals, providing visual aid in real-time for disabled people, and realization of text-free animation applications are just to name a few. Therefore, in this study, a language-independent lip-sync method that is based on extended linear predictive coding is proposed. The proposed method operates on baseband electrical signal that is acquired by a standard single-channel off-the-shelf microphone and exploits the statistical characteristics of acoustic signals produced by human speech. In addition, the proposed method is implemented on an embedded system, tested, and its performance is evaluated. Results are given along with discussions and future directions.Öğe Measurement based direction of arrival estimation for frequency hopping signals(IEEE, 2020) Kaplan, Batuhan; Kahraman, İbrahim; Ekti, Ali Riza; Yarkan, Serhan; Çırpan, Hakan AliIn this paper, the problem of measurement-based angle of arrival estimation for frequency hopping signals is discussed. While the angle of arrival estimation is important information for many subjects, obtaining the angle of arrival estimation for frequency hopping signals is needed a different approach. A method based on resampling and noise reduction is proposed upon the reconstruction of the wideband received frequency hopping signal under the real-world conditions by using time-frequency analysis. Then, multiple signal classification (MUSIC) algorithm is used to obtain measurement based angle of arrival estimation of frequency hopping signals. The effectiveness of the proposed method is shown by the results of testing for two different location points.Öğe Microstrip patch antenna array: Improved slitted rectangular design(IEEE, 2017) Altuntaş, Muhammed Efe; Kaya, Sedat; Orhan, Mehmet Emin; Hellaç, Yetkin; Bayrak, Hakan; İmeci, Mustafa; Güngör, Oğuzhan Salih; İmeci, TahaIn this study, a recessed rectangular microstrip patch antenna which is for C hand, working at 4.08GHz frequency with less than -18dB S11 has been designed simulated, built and tested. Microstrip antennas have the advantage of easy and cheap production process. This study aims that achieving maximum gain while changing the design parameters as lengths of dimensions and recessed parts. As a simulation result, electric field radiation pattern shows more than 10dB gain. There is a comment about the differences of simulation and fabrication results and further improvement detailed were discussed.Öğe Double U-slot microstrip patch antenna(IEEE, 2015) Özgün, Özer; Macit, Fatih; Mertoğlu, Furkan; İmeci, TahaIn this work, a doble U-slotted, circular polarized micrrostrip patch antenna is designed. The antenna is ground-fed and the geometry has two U-Shaped slots in the middle and corners are truncated. As a result of simulations, input match is -12.17 dB and gain is 6.51 dB at 4.08 GHz. The antennas double U-Slotted and circularly polarized geometry makes it different than similar antennas in literature.Öğe Microstrip band pass filter design(IEEE, 2015) Yeşilyurt, Orhan; Köksal, Mustafa; İmeci, TahaIn this study, a microstrip structure has been suggested for use in open ring resonator microwave filter. This resonators are used in order to design a bandpass filter. Open ring resonator structures characterized by higher performance and have good frequency response for bandpass filters. Both resonator and band-pass filter is design with a simulation program and two frequency response is presented.Öğe Aşırı akım röle koordinasyonu için bozkurt algoritmasının kapsamlı performans analizi(Tmaed, 2022) Atsever, Mert Bekir; Hocaoğlu, Mehmet HakanGüç sistemlerinde aşırı akım koruma pratiği, mesafe koruma pratiğinden daha ekonomik ve yaygındır. Ayrıca dağıtım şebekelerinin büyük bir çoğunluğunda aşırı akım koruma kullanılmaktadır. Bu durum, dağıtım şebekelerinde kullanılan aşırı akım rölelerin koordinasyonun en uygun şekilde tasarlanmasını gerekli kılmaktadır. Aksi halde sistemde gerçekleşen bir arıza sırasında röleler istenildiği gibi çalışamaz. Aşırı akım röleleri arasında koordinasyonun etkili ve seçici olabilmesi için röle ayar parametrelerinin şebekeye uygun ayarlanması gerekmektedir. Dağıtım şebekelerinin genişlemesi ile birlikte röle ayarlarının hesaplanması veya güncellenmesi zorlaşmıştır. Bu nedenle aşırı akım röle koordinasyonu yüksek sayıda kısıt içeren optimizasyon problemi şeklinde kurgulanmaktadır. Optimizasyon problemini çözümü noktasında ise peç çok meta-sezgisel algoritmalar geliştirilmiştir. Bu çalışmada IEEE 8 Baralı test şebekesi için Bozkurt Optimizasyon Algoritması (BOA) başarılı bir şekilde uygulanmış ve kapsamlı performans analizi gerçekleştirilmiştir.Öğe BIBC matrix modification for network topology changes: Reconfiguration problem implementation(MDPI, 2021) Şeker, Ayşe Aybike; Gözel, Tuğba; Hocaoğlu, Mehmet HakanAbstract: The topology of a distribution network can be represented by a bus injection to branch current (BIBC) matrix. It has been introduced and used for load flow analysis of distribution networks. In this paper, a method for BIBC matrix modification is developed to use in applications which require a topology change representation. Proposed method that reflects the changes in configuration in the system BIBC matrix is implemented in distribution network reconfiguration problem. With providing potential solutions for network operational and planning requirements such as necessitate changes in configurations to transfer the loads to a different substation, ease the loading of equipment, conduct planned maintenance and reduce network losses during the normal operation with renewables, storage and other uprising technologies, reconfiguration may also be useful for emergencies, accidents, attacks and weather-related disasters. The BIBC modification process provides the knowledge of possible switches to open and the direction of power flow without any need to further radiality or continuity check. The proposed method needs only initial network topology information that makes it suitable to apply on any distribution network and to use with any search method or heuristic/meta-heuristic optimization algorithm. Efficiency of the method is investigated on systems with voltage dependent and time varying loads.Öğe 10 GHz’lik rezonans frekansında 9dB kazanç ile ortak beslemeli dikdörtgen MŞYA(IEEE, 2017) Osmani, Festim; Athar, Muhammad Arsalan; Çelen, Mustafa; Dönmez, Zeliha; Bostan, Zeynep; İmeci, TahaBu makale, ortak besleme tekniğinden yararlanılarak 4 elementli mikroşerit yama anten tasarımını gösterir. Tasarım 10.17 GHz rezonans frekansında çalışılmıştır. Antenin giriş yansıtma katsayı parametresi, merkez frekansta -30 dB yol kaybına sahiptir. Antenin yönelme kazancı yaklaşık olarak 9.2 dB’dir. Antenin tasarım ve simülasyonu için Sonnet Software programı kullanılmış olup, üretilmesi için çift taraflı FR4 bakır levha belirlenmiştir.Öğe Modeling and analysis of short distance sub-terahertz communication channel via mixture of gamma distribution(IEEE, 2021) Tekbıyık, Kürşat; Ekti, Ali Rıza; Kurt, Güneş Karabulut; Görçin, Ali; Yarkan, SerhanAbstract—With the recent developments on opening the terahertz (THz) spectrum for experimental purposes by the Federal Communications Commission, transceivers operating in the range of 0:1THz-10THz, which are known as THz bands, will enable ultra-high throughput wireless communications. However, actual implementation of the high-speed and high reliability THz band communication systems should start with providing extensive knowledge in regards to the propagation channel characteristics. Considering the huge bandwidth and the rapid changes in the characteristics of THz wireless channels, ray tracing and one-shot statistical modeling are not adequate to define an accurate channel model. In this work, we propose Gamma mixture based channel modeling for the THz band via the expectation-maximization (EM) algorithm. First, maximum likelihood estimation (MLE) is applied to characterize the Gamma mixture model parameters, and then EM algorithm is used to compute MLEs of the unknown parameters of the measurement data. The accuracy of the proposed model is investigated by using the Weighted relative mean difference (WMRD) error metrics, Kullback-–Leibler (KL)-divergence, and Kolmogorov-Smirnov (KS) test to show the difference between the proposed model and the actual probability density functions (PDFs) that are obtained via the designed test environment. To efficiently evaluate the performance of the proposed method in more realistic scenarios, all the analysis is done by examining measurement data from a measurement campaign in the 240GHz to 300GHz frequency range, using a well-isolated anechoic chamber. According to WMRD error metrics, KL-divergence, and KS test results, PDFs generated by the mixture of Gamma distributions fit to the actual histogram of the measurement data. It is shown that instead of taking pseudo-average characteristics of sub-bands in the wide band, using the mixture models allows for determining channel parameters more precisely.Öğe Design and implementation of a programmable logic controller using PIC18F4580(Institute of Electrical and Electronics Engineers Inc., 2018) Şanver, Ufuk; Yavuz, Erdem; Eyüpoğlu, Can; Uzun, TuncayUse of electricity in industry opened a new age which is dominated by industrial automation. In the beginning, automation systems were based on electro-mechanical systems consisting of relays and contactors. Developments in semiconductor technology inevitably transformed the existing structure and cause electronic-controlled Programmable Logic Controller (PLC) to prevail in the automation systems. PLCs consist of a microcontroller/microprocessor, relay or transistor for switching, isolating equipment such as opto-couplers and voltage converter/inverters. Industrial PLCs are quite expensive devices. In this study, design and implementation of a low-cost PLC using PIC18F4580 microcontroller are realized. Special software including a graphical user-interface is developed for programming the PLC and transferring code data to the device. Both ladder diagram and word instructions can be used for programming the PLC.Öğe Mobile visual acuity assessment application: AcuMob(Istanbul University, 2017) Akbulut, Akhan; Aydın, Muhammed Ali; Zaim, Abdül HalimThis paper presents a mobile healthcare (mHealth) system for estimation of visual impairment that provides easiness by specifying the degree of an eye as orthoscopes. Our proposed system called AcuMob which is an Android based mobile application aimed to be used by patients who have myopia. In the crowd society, our proposed app will be implemented faster than the traditional ophthalmologic examination treatments as an alternative. Because AcuMob can be used in everywhere in any time slot, it is offered in the area where the ophthalmologist is not available. The system is developed with using Xamarin framework and voice commands are used to interact with mobile app. Some preferable letters that are suggested by the ophthalmologists were used in the system. The letter categories are specified according to letters' sizes. In the start-up screen, the biggest letter is demonstrated and if the user responds correct answer, the letter's size is being smaller. However, if the user says wrong answer three times consecutively, eyesight ratio is produced by the system to the user referencing to Snellen Chart's information. This article has aimed at making a prediction about the visual impairment's degree. Thanks to AcuMob, people can get idea about their visual acuity without consulting to an eye medical doctor (MD). For the evaluation of systems' reliability, field tests were performed at Bayrampaşa Göz Vakfi Hospital in Istanbul with two ophthalmologist specialists. At the end of trials, the actual diagnosed degrees and the equivalent degree of eyesight ratios according to Snellen Chart's information is compared and the success rates are shown. The system achieved at the 65% of average success rate, which can give users an idea about current condition of their visions.Öğe Veri ve ağ güvenliği için uygulama ve analiz çalışmaları(İstanbul Ticaret Üniversitesi, 2017) Kaya, Ömer Faruk; Öztürk, ErdinçGünümüzde artık bir yaşam biçimi halini alan bilgisayar dünyasında dosyaları, bilgileri özetle veriyi korumak en önemli konu olarak karşımıza çıkmaktadır. Özellikle paylaşımlı ve halka açık iletişim sistemlerinde veri güvenliği daha da fazla önem arz etmektedir. Bir diğer önemli konu ise ağ güvenliğidir ki son kullanıcı ve merkez arası haberleşme protokolleri ile sağlanan haberleşme yöntemlerinde veriyi korumak hayati önem taşır. Ağ güvenliği tedbirleri verinin iletimi sırasında onun korunmasını esas alır. Bu çalışmada özellikle 150’ye yakın saha lokasyonu olan bir kamu kuruluşunda saha ile merkez arası network ve veri güvenliği ile merkezde bu alanda alınması gereken önlemlerin vurgulanması hedeflenmiştir. Ayrıca, İstanbulkart’ın İspark uygulamalarına entegrasyonu sırasında bu önlemlerin uygulanması ile ortaya çıkan güçlükler ve sonuçlar bu çalışma ile sunulmuştur.Öğe Otopark sistemlerinde İstanbul kart uygulaması İspark örneği(İstanbul Ticaret Üniversitesi, 2017) Güngör, Ali; Öztürk, ErdinçGünümüzde akıllı tablet ve cihazlar sayesinde bilgisayar çağı bir üst seviyeye çıkmış bulunmakta ve yaşam standartlarımız da bu doğrultuda değişmektedir. Kullandığımız ödeme sistemleri, kredi kartları, debit kartlar vb. hayatımızın bir parçası olmuştur. Artan nüfus popülasyonu beraberinde akıllı şehirciliği beraberinde de güvenli alternatif ödeme sistemlerini getirmiştir. Bunlardan en önemlisi gelecekte hayatımıza daha çok etki edecek olan akıllı kartlardır. İstanbul gibi metropoliten ve trafiğin yoğun olduğu bir şehirde toplu taşımada büyük rol oynayan akıllı kartlar otopark sektöründe de kullanılmalıdır. Akıllı kartlar kredi kartlarından ve diğer debit kartlardan daha güvenlikli diyebileceğimiz bir DES şifreleme yapısına sahiptir. Ayrıca her akıllı kartın kendine ait bir ID numarası olması, otoparkları kullanan müşterilerin bıraktığı kullanım istatistiklerinin toplanmasında ve kullanılmasında etkili olmaktadır. Akıllı kartlar kullanımı kolay, güvenliği yüksek, kişisel veri açığı olmayan, dolumu basit, kırılması zor bir NFC ürünüdür. Bu nedenle otoparklarda ödeme aracı olarak kullanılması nakit ve diğer kartlara göre her zaman bir adım önde olmuştur.Öğe Adaptive Network-Based Inference System Models On Multiband Patch Antenna Design(TUBITAK Scientific & Technical Research Council, 2015) Demircioglu, Erdem; Sazlı, Murat Husnu; Sengül, Orhan; Imeci, Sehabeddin Taha; Ilgın, Hakkı AlparslanIn this study, an adaptive network-based fuzzy inference system (ANFIS) for multiband microstrip patch antenna (MMPA) modeling is proposed. The MMPA includes a single patch with inverted L-shaped stubs on the edges. The antenna production process needs iterative runs of the electromagnetic (EM) simulator, fabricating and testing the simulated antenna to find the optimum geometry. Production processes (design, simulation, fabrication, and testing) and the cost computation time add to the overall manufacturing expenses. A computer-aided modeling approach using the ANFIS is developed and trained with data acquired from the EM simulators, Sonnet Suites and AWR AXIEM, and measurement data. The overall data set includes 7777 input-output pairs, of which 3338 are used for the testing of the ANFIS model. The trained ANFIS model provides accurate and reliable results compared with the EM simulators and measured data.
