Mühendislik Fakültesi, Elektrik Elektronik Mühendisliği (İngilizce) Bölümü Koleksiyonu

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https://hdl.handle.net/11467/9347

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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, Hammad
Modern 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.
Yüksek oranda yerel elektrik santralleriyle beslenmekte olan dağıtım şebekelerinin etki haritalarının çıkarılması
(2019) Gözel, Tuba; Hocaoğlu, Mehmet Hakan; Şeker, Ayşe Aybike; Çetin, Tansu; Tunçel, Süleyman; Zegrar, Salah Eddine; Takcı, Mehmet Türker; Peposhi, Jeshar
Son yıllardaki nüfus artışı ve sanayinin gelişmesi enerjiye olan ihtiyacı artırmaktadır. Sınırlı miktardaki fosil kökenli enerji kaynaklarının artan talebi karşılayamaması ve çevreyi kirletmesi, ilgili birimleri yeni ve yenilenebilir enerji kaynaklarına yöneltmektedir. Özellikle de karbon emisyonunu azaltma ile ilgili devlet politikaları sayesinde yenilenebilir enerji kaynakların güç sistemlerinde hızla artan oranda yer almaktadır. Şebekenin güvenilirliğini ve enerji kalitesinin devamını sağlamakla yükümlü şebeke operatörleri artan Yerel Enerji Santrallerinden (YES) kaynaklanan risklere karşı çözüm üretmek ve yatırım yapmak zorunda kalmaktadır. YES’lerin en önemli sorunlu yerleştirme sonrası ortaya çıkacak problemleri belirlemek ve azaltmak için kullanılacak tedbirlerin belirlenmesidir. Bu kapsamda projede geliştirilen metotla dağıtım operatörlerinin YES yerleştirme stratejilerinde ve değişen geleneksel dağıtım şebekesinin ihtiyacı olan yatırımların geciktirilmesinde yol gösterecek bir etki haritası çıkarılması için yöntem geliştirilmiştir. Bu projede artan YES’in şebekede aktif, reaktif güç kaybı ve gerilim profiline etkisini analiz etmek için analitik ifadeler çıkarılmış, GAMS, Yapay Arı Kolonisi algoritması ve Izgara Arama algoritması ile analizler yapılmıştır. Kayıpları ve gerilim sapmasını ayrı ayrı en aza indiren en uygun ve arttırmayan azami YES büyüklükleri belirlenmiştır. Ayrıca kayıpları ve gerilim sapmasını aynı anda en aza indiren ya da arttımayan çok amaçlı optimizasyon problemleri çözülerek YES’ler belirlenmiştir. Şebekeye eklenebilecek YES’lerin kapasitesinin arttırılmasına karşılık değişecek şebeke işletme koşullarını öngören bir etki haritası için bir yöntem geliştirilmiştir. Geliştirilen algoritmalarla YES tipi, müşteri dağılımı dikkate alınarak, şebekenin yapısına uygun, güvenilir, kolay uygulanabilen ve sonuca hızlı ulaşılabilen özelliklere sahip bir arayüz tasarlanmıştır. Arayüz ile sabit yük ve üretimin olduğu sistemler ve zamana bağlı yük ve üretimin olduğu sistemlerde farklı senaryolar ve farklı amaçlar için analizler yapılmış etki haritaları elde edilmiştir.
A low-cost, real-time, and short-range software-defined digital wireless communications transceiver design and implementation at baseband
(Gazi Üniversitesi Mühendislik-Mimarlik, 2015) Akın, Merve; Çakır, Meryem; Yıldız, Dilara; Özgen, Haluk; Yarkan, Serhan
Physical layer transceiver design lies in the heart of all wireless communications systems. However, each and every emerging wireless communications technology forces the already-existing transceiver designs and their corresponding hardware to change. In addition, due to the dramatic increase in number of emerging wireless technologies, there are serious concerns regarding the utilization of valuable radio spectrum. Recently, cognitive radio concept is proposed in order to provide a new perspective for the aforementioned concerns. Operating on a software-defined platform, cognitive radio introduces flexibility in design of utmost level; adapts itself to the dynamic radio environment; senses the radio spectrum steadily to be aware of it; and learns about its past experiences in order to plan and take action in the future in a beter way. Therefore, in this study, a software-defined wireless acoustic baseband transceiver design whose each and every parameter could be modified, updated, and changed with utmost flexibility is established toward realization of cognitive radio. Mathematical analysis and a simulation environment of the design are provided too. A real-time implementation of the transceiver is realized as well in order to both demonstrate an operating prototype and set up a testbed for software-defined platforms. Results for theoretical, simulation, and real-time performance of the transceiver are given along with relevant discussions and future directions.
Black body radiation problem with an infinite speed of light perspective and some consequences
(Institute of Electrical and Electronics Engineers Inc., 2024) Yener, Namık
The 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.
A novel microstrip patch antenna design for mobile applications
(IEEE Computer Society, 2014) Elmas, Volkan; Demircioğlu, Erdem; İmeci, Taha
In 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.
Electromagnetic charge density with a causal current density vector and infinite speed of light
(Institute of Electrical and Electronics Engineers Inc., 2024) Yener, Namık
In 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.
Infinite Speed of Light and Compton Scattering
(Institute of Electrical and Electronics Engineers Inc., 2024) Yener, Namık
It has been theoretically demonstrated by the author in past work that when a charge density starts an arbitrary motion abruptly in time an infinite speed of light c will commence along with emergence of a magnetic charge. In another paper presented at the present PIERS we show that an infinite c exists even with a current density vector motion which starts continuously in time provided that charge density is a noncausal function and is nonzero at the instant of inception of the motion. In other words, causality of the current density vector is sufficient to obtain this effect. One outcome of the infinite speed of light finding is the exclusion of an ultraviolet catastrophe in the black body radiation problem. This removes the need for an energy discretization. This result is presented by the author in a third paper at the present PIERS. Therefore, in the present work we attempt to model the Compton effect with an infinite speed of light perspective. Thus, regardless of whether the recoiled electron starts a motion which is temporally continuous or abrupt at t = 0 we suppose that speed of light is infinite for the wave emitted by the electron. By also accounting for the emerging magnetic charge which we know accompanies an infinite c, a classical electromagnetic field structure is proposed for the effect. The principle of conservation of energy is used to derive a relation for the scattering angle. The auxiliary relation involving the angle of recoil for the electron (and the magnetic charge) is assumed to be true and the derived relation is solved for the scattering angle using the Newton-Raphson method. Comparison with the scattering angle obtained by the discretization of energy approach shows good agreement for recoiled electron velocities of up to 2×107 m/s. It is concluded that classical electromagnetic theory with an infinite speed of light assumption can model the Compton effect.
An Experimental Setup for Mechanical Vibration Analysis Using VLC
(Institute of Electrical and Electronics Engineers Inc., 2024) Yılmaz, Ahmet Mücahit; Boyacı, Ali; Ekti, Ali Rıza; Yarkan, Serhan
This study explores the potential applications across various domains, including earthquake detection and warning systems, where the system's sensitivity to ground vibrations can contribute to early seismic event detection. Additionally, the study paves the way of developing applications of VLC/T in mechanical vibration and stability analysis of engines and platforms, offering insights into structural integrity and performance optimization. These multifaceted applications underscore the adaptability and potential of VLC/T systems in diverse fields, heralding advancements in sensing, communication, and security technologies. To achieve this, in this study, Peak to Average Power Ratio (PAPR) is proposed to represent the impact of mechanical shocks and vibrations generated by several weights dropped onto the platform with which the receiver is fixed. Even though non-contact measurement methodology is preferred for various reasons, the proposed measurement campaign obtains the data in contact form; however, the system and signal model proposed in this study could easily be extended into non-contact form. Considering the fact that the proposed measurement campaign employs off-the-shelf products, it is cost-effective and very scalable. © 2024 IEEE.
A comparison on energy detector and CNN-based detector
(IEEE, 2020) Tokgöz, Gamze Kirman; Tekbıyık, Kürşat; Kurt, Güneş Karabulut; Yarkan, Serhan
In 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.
An acoustic signal based language independent lip synchronization method and its implementation via extended LPC
(IEEE, 2020) Cankurtaran, Halil Said; Boyacı, Ali; Yarkan, Serhan
Processing 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.
Measurement based direction of arrival estimation for frequency hopping signals
(IEEE, 2020) Kaplan, Batuhan; Kahraman, İbrahim; Ekti, Ali Riza; Yarkan, Serhan; Çırpan, Hakan Ali
In 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.
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, Taha
In 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.
Circular Patch Antenna with Circular and Rectangular Slots
(IEEE, 2017) Toğçuoğlu, Nurettin Baha; Albayrak, Yunus; Saylık, Mustafa Niyazi; Daye, Melik Ahmet; Bal, Mustafa; İmeci, Mustafa; İmeci, Taha
The microstrip patch antenna which is a type of antenna manufactured and measured to operate at the frequency of 9.93 GHz. The results of Sill simulation and measurement are in good agreement. The designed antenna has one circular slot in the center and two rectangular slots with adding double wings to the right and left sides of the antenna differently from reference antenna. These transactions have been made to get more gain. The S11 and antenna gain simulations were measured as -11.64 dB and 10.15 dB respectively. Antenna was designed for SHF-10 GHz band.
7 GHz microstrip low pass filter
(IEEE, 2015) Kazancı, Nusret Can; Yüksel, Baki; İmeci, Şehabeddin Taha
In this paper, a low pass microstrip filter that has 7 GHz cut off frequency was designed, simulated, built and tested by Butterworth approach. The laboratory measurements have been conducted as well. Result of the measurements carried out, we have come to realize that the cut off frequency displayed some unwanted losses which are thought to be caused by the errors in production process.
Parallel line microstrip low pass filter design
(IEEE, 2017) Günaslan, Mahmut Bera; Çankaya, Göksel; İrken, Kaan; İmeci, Taha; Güngör, Oğuzhan Salih
In this design, low-pass filter that has 2 GHz cutoff frequency was designed for L-band applications. Low impedance tnicrostrip structure is used to improve the selectivity and productivity of filter. In this design, the cut-off signal 2.06 GHz is tested by Sonnet software. In real test, some inconsistency was seen due to deformation during to production.
Fractional-rate radiometer for spectrum sensing based on I/Q branch separation
(IEEE, 2015) Boyacı, Ali; Yarkan, Serhan; Sönmez, Ahmet Coşkun
Radiometer has a peculiar place among spectrum sensing techniques available in the literature, because it has a simplistic design and is known to be the optimal detector in the absence of a priori knowledge about the signal to be detected. In this study, it is shown that simplicity in the traditional radiometer design could further be improved while its performance is maintained. The proposed method exploits the inherent orthogonality between the I/Q branches and reduces the total number of addition and multiplication operations at baseband. Results are validated by the experimental data collected under different digital modulation scenarios. Relevant discussions and future directions are outlined as well.
Double U-slot microstrip patch antenna
(IEEE, 2015) Özgün, Özer; Macit, Fatih; Mertoğlu, Furkan; İmeci, Taha
In 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.
Microstrip band pass filter design
(IEEE, 2015) Yeşilyurt, Orhan; Köksal, Mustafa; İmeci, Taha
In 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.
Ku band microstrip patch antenna
(IEEE, 2015) Çalışkan, Kaan; Özkul, Salih Haydar; Sarıgül, Hasan Cafer; Özmen, Yunus Emre; İmeci, Taha
In this study, a microstrip antenna operating at 11.56 GHz is designed and simulation results are presented. The antenna air thickness is 5 mm and the gap between the antenna and ground is 2.5 mm. Cell size is regarded as 0.75 mm. The antenna was simulated in the frequency range of 5-15 GHz. S11, the input reflection coefficient parameter has the value of -27.50 dB at the center frequency. The resonance frequency has the gain value of 4.72 dB.
RFID (radio-frequency identification) planar low loss antenna design
(IEEE, 2015) Karataş, Umut Can; Tuzcu, Saygı Kaan; İmeci, Taha
In this study, RFID planar antennas are explained. We simulated an H-Shaped Antenna to validate our structure and to develop an analythic method to determine the geometry parameters. This antenna is designed becauseit's dimensions are smaller than other RFID antennas found in the literature. Stubs are rectangular shape so that it's easy to modify. The input match, S11, is -28.09 dB and, electric field theta polarized gain is 4.41 dB at 3.84 GHz.

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