Elektrik-Elektronik Mühendisliği Bölümü / Department of Electrical and Electronics Engineering
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Browsing Elektrik-Elektronik Mühendisliği Bölümü / Department of Electrical and Electronics Engineering by Publisher "IEEE"
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Publication Analysis of Single Flying Capacitor Converter by the State-Space Averaging Technique(IEEE, 1988) Bilgiç, Mehmet Oruç; Ehsani, M.; 1616The single flying capacitor converter (SFCC) is a two-quadrant power supply for energy storage and transfer system. It has applications in nuclear research and pulsed power systems in which superconductive coils are used in superconductive magnets. The authors derive analytical expressions for the time-averaged behavior of the SFCC by using the state-space averaging technique. Useful expressions are found for the average behavior of the SFCC. The results can be used in the design, control, and optimum operation of the system.Publication Capacitor coupled converter (C3) for high power DC conversion(IEEE, 1995) Ehsani, Morteza; Bilgiç, Mehmet Oruç; Khan, S.; Laskai, L.; Jeong, Seung-Gi; 1616The bang-bang controlled capacitor coupled converter (C3) is described in this paper. Due to the converter's inherent commutating property, the C3 can accommodate thyristors as well as high-power gate turn-off switches, due to zero-current switching transitions. The zero-current switching is achieved at no current stress increase, therefore, the topology is considered appropriate for high-power processing. DC and small signal AC models are derived for the bang-bang controlled C3, a design procedure is proposed, and simulation results are discussed. Finally, oscillograms from a proof of principle prototype circuit are presentedPublication Capacity Loss Analysis Using Machine Learning Regression Algorithms(IEEE, 2022) Atay, Sergen; AYRANCI, AHMET AYTUĞ; Erkmen, BurcuIn this study, time dependent measurements of the power capacitor, which is the main equipment of a compensation unit, are given. The power capacitor is actively working in an industrial facility. Six months of the data from this capacitor were recorded and tests were carried out using Machine Learning (ML) algorithms for its remaining useful life. ML algorithms were selected from the algorithms that used for regression problems. In the study, Support Vector Machine (SVM), Linear Regression (LR) and Regression Trees (RT) algorithms were used. The rated powers of the analyzed capacitor are 50kVAR and 25kVAR from the active plant. The data set was created by running the capacitor continuously for 6 months and the capacity loss was examined with using ML algorithms. The algorithm that gives the best result in the regression analyzes is the LR algorithm. With the results obtained, it is possible to analyze how long the useful life of capacitors with the same characteristics have under the same stress.Publication Doku Analiz Yaklaşımına Dayanan Yeni Bir İris Tanıma Yöntemi(IEEE, 2005) Akan, Aydın; GÜRKAN, GÜRAY; 113297; 2918Bu çalışmada, iris yardımı ile kişi tanıma konusunda doku analizine dayalı yeni bir yöntem sunulmaktadır. İris görüntüleri bir ön işlemeden geçirildikten sonra doku analizine dayanan öznitelik vektörleri çıkarılmaktadır. Normalize edilen iris görüntüsü dikey logaritmik olarak örneklenir ve dairesel simetrik Gabor süzgeçlerinden geçirilir. Süzgeç çıkışları üzerinde kayan bir pencere altındaki piksellerin ortalama mutlak sapma değerleri öznitelik olarak elde edilir. Önerilen yöntem, iris ile kişi tanıma sisteminde aranan önemli niteliklerden ölçek ve dönüş ile değişmezlik özelliklerine sahiptir. Sistemin yazılım kısmı, Delphi derleyicisi ile Windows ortamında gerçeklenmiştir.Publication EEG Sinyalinin Anestezi Sırasındaki Topografik ve Zamansal İzge Analizi(IEEE, 2018) Uslu, Atilla; Cebeci, Bora; Erdoğan, Ezgi T.; Kaşıkçı, Itır; Seyhan, Tülay Ö.; Akan, Aydın; Demiralp, Tamer; GÜRKAN, GÜRAY; 113297; 221283; 141798; 167802; 2918; 6916Bu çalışmada EEG sinyalinin anestezi altındaki izgesel değişimi, zamansal ve uzaysal olarak incelenmiştir. Bu amaçla kullanılan yöntemler arasında, günümüz anestezi derinliği takip cihazlarının da kullandığı bilinen SEF-90, α-β bandı güç oranları ve izgesel entropi yer almaktadır. Ayrıca doğrusal olmayan sistemlerin analizinde kullanılan Higuchi fraktal boyutu da karşılaştırma olarak incelenmiştir. Uzaysal analiz sonucunda, normal bireylerde oksipital bölgede görülen baskın alfa aktivitesinin artan anestezi derinliği ile frontal bölgeye kaydığı doğrulanmış ve ilgili topografik gösterimler sunulmuştur.Publication EOG Sinyalleri için Sınıflandırma Algoritmalarının Karşılaştırılması(IEEE, 2012) Gürkan, Serkan; Uşaklı, Ali Bülent; GÜRKAN, GÜRAY; 113297; 244333; 118889Bu bildiride, belirli göz hareketleri sonucu elde edilen elektrookülogram (EOG) sinyallerinin sınıflandırılması için Destek Vektör Makinesi (DVM) ve Yapay Sinir Ağı (YSA) yöntemleri karşılaştırılmaktadır. Göz hareketleri kullanarak kontrol edilecek bir sistemin parçası olarak seçilen yöntemler, doğruluk ve hız parametreleri bakımından karşılaştırılmıştır. Alınan EOG sinyalleri, yatay (sağ ve sol), dikey (aşağı ve yukarı) ve kırpma biçimindeki 5 farklı göz hareketinden oluşmaktadır. 20 denekten, yatay ve dikey bileşenli iki EOG kanalından alınan sinyal kümesinden, 3 elemanlı öznitelik vektörleri hesaplanmıştır. Öznitelik vektörlerinin ilk iki elemanı, kanallardaki tepe genlik değerinden, üçüncüsü ise bu çalışmada özgün olarak önerilen parametre olan, aktif kanala ait basıklık değerinden oluşmaktadır. Deneklerden elde edilen öznitelik vektörlerinden rasgele 10 tanesi adı geçen sınıflandırıcıların eğitimi, kalan 10 tanesi de başarımlarını değerlendirmek için kullanılmıştır. Çevrimdışı olarak yapılan testler sonucu her iki sınıflandırma yönteminde de % 100 başarı elde edilmiştir. Ortaya çıkan cevap süreleri de iki yöntemin gerçek zamanlı olarak kullanıma uygun olduğunu göstermektedir.Publication Four-quadrant switch-mode gyrator(IEEE, 2008-05-23) Dinçbakır, Cenk; Bilgiç, Mehmet Oruç; 282656; 1616A gyrator design based on an inductor coupled double bridge converter is presented. It is shown that this gyrator can operate in four-quadrant mode by using bi-directional MOS switches without the necessity of any feedback control circuit. There are different usage areas of such a gyrator. Some of which can be used for conversions of voltage to current, current to voltage, capacitor to inductor and Resistance to Resistance. In this paper, the dynamic and static gyrator behavior is first simulated and some of above conversions are also tested.Publication Fuzzy logic based control of switched reluctance motor to reduce torque ripple(IEEE, 1997) Derdiyok, A.; İnanç, N.; Özbulur, Veysel; Pastacı, Halit; Bilgiç, Mehmet Oruç; 202694; 6012; 1616This paper presents torque ripple reduction of a switched reluctance motor (SRM) by using a fuzzy speed controller. For this purpose, current control is applied with a fuzzy speed controller. The fuzzy controller adjusts the value of reference current to keep speed constant. In this study, the nonlinear model of a SRM is used and the motor used in simulation is an 8/6 SRM with a C-Dump converter.Publication Inverse Dual Converter (IDC) for High Power DC-DC Applications(IEEE, 1990) Ehsani, Mehrdad; Husain, Iqbal; Bilgiç, Mehmet Oruç; 1616The inverse dual converter (IDC), suitable for high-power DC-DC conversion applications, is presented. The IDC is a voltage source converter with an AC link and has been derived from an inductor converter bridge. This capacitor commutated converter is capable of continuous voltage step-up or step-down control over a wide range without the need of a transformer. In addition to high-frequency switching the converter is characterized by soft switching techniques, reducing constraints on the ratings of the switches. The average model developed with the help of gyrator theory provides sufficient information for control strategies and design considerations. The results of gyrator modeling and computer simulation are compared with experimental results obtained from a prototype IDC.Publication Inverse dual converter (IDC) for high power DC-DC applications(IEEE, 1993) Ehsani, M.; Husain, I.; Bilgiç, Mehmet Oruç; 1616A family of DC-DC converters suitable for high-power applications is introduced. The inverse dual converter (IDC) is capable of continuous voltage step-up or step-down control over a wide range of and without the need of a transformer. Experimental verification of the analysis is given for the simple single-phase IDC. Some of the more sophisticated members of the IDC family are described, and their characteristics and possible application, are mentioned.Publication Low Cost Maximum Power Point Tracking Method For Solar Battery Charging(IEEE, 2013-09-25) Koral, Ahmet Can; Bilgiç, Mehmet Oruç; GÜRKAN, GÜRAY; 113297; 1616In this paper, we propose a low cost charger circuit with a maximum power point tracking method (MPPT) that is a key factor in photovoltaic systems. The solar panel output voltage, which is known to be generated by series connected solar cells (also called as photovoltaic cells), was adjusted to a constant voltage to maximize the transferred power even at different intensities of sunshine. By modifying the feedback circuit of a commercially available buck converter, we managed to constantly adjust the operating voltage of the solar panel to its point of maximum power being a different version of maximum power point tracker.Publication Magnetically inflatable SPS with energy storage capability(IEEE, 1995) Ehsani, M.; Bilgiç, Mehmet Oruç; Patton, A. D.; Mitra, J.; 1616A new approach to superconductive magnetic energy storage (SMES) for solar power satellite (SPS) with inherent rigidity is introduced in this paper. The rigidity of this SMES originating from the electromagnetic forces within it, can eliminate the need for mechanical building blocks for support structure. This force can also be used for the deployment of the system in space. In addition, the storage capability of the system allows its use in low Earth orbit (LEO) which reduces the launching and transmission costs. The paper also discusses the basic design and the operation of the proposed SPS system.Publication Monofonik Türk Makam Müziğinde İşitsel Melodi Kestirimi(IEEE, 2020) ŞİMŞEK, BERRAK ÖZTÜRK; Akan, AydınBu çalışmada, monofonik Türk makam müziği eserlerinde baskın işitsel melodi çıkarımı için yeni bir yöntem önerilmiştir. Müzik sinyalleri, Geliştirilmiş Değişken Mod Ayrıştırma Yöntemi kullanılarak ayrıştırılır ve temel frekanslar, her moddaki merkez frekanslarının hesaplanmasıyla elde edilir. Baskın melodi hattını tahmin etmek ve seçmek için her penceredeki farklı frekans bilgilerinden bazı parametreler belirlenir. Elde edilen sonuçlar, batı müziği için kullanılan sinyal işleme algoritmaları olan YIN ve MELODIA ile karşılaştırılmıştır. Değerlendirme aşamasında uluslararası standartlara bağlı kalınarak MIREX kriterleri kullanılmaktadır. Simülasyon sonuçları, Geliştirilmiş Değişken Mod Ayrıştırma Yönteminin karşılaştırmada kullanılan diğer yöntemlere göre daha başarılı sonuçlar verdiğini göstermiştir.Publication Multifractality Analysis of Respiratory Signals(IEEE, 2020) SAATÇI, ESRA; SAATÇI, ERTUĞRULFractal analysis was used to analyze the biomedical signals which are emerged from the fractal structures in the human body. Respiratory signals, such as airflow, mouth pressure, lung volume comprise the complex relationship which has not been inspected and how it is linked to the fractal structure of the lung has not been scrutinized. Thus the aim of this study is to determine the mono or multifractal property of the respiratory signals by using well known method, Multifractal Detrended Fluctuation Analysis (MF-DFA). Real signals were analyzed by utilizing already proposed MF-DFA algorithm and generalized Hurst exponent values were shown for different scales. In the results, it was shown that respiratory signals are fractional Brown motion type signals and fractal properties exhibit less intersubject change. Finally, it was proved that apart from the airflow and lung volume, respiratory sounds and signals are multifractal signals. It appears that the presence of long-memory property of the lung is the primary reason of the multifractality.Publication New architectures for space power systems(IEEE, 1995-08) Ehsani, M.; Bilgiç, Mehmet Oruç; Patton, Alton D.; Mitra, J.; 1616Electric power generation and conditioning have experienced revolutionary development over the past two decades. Furthermore, new materials such as high energy magnets and high temperature superconductors are either available or on the horizon. Our work is based on the premise that new technologies are an important driver of new power system concepts and architectures. This observation is borne out by the historical evolution of power systems both in terrestrial and aerospace applications. This paper introduces new approaches to designing space power systems by using several new technologies. Two new architectures are introduced: the current source current intensive system and the articulate system. Basic characteristics of these systems have been investigated. Some aspects of the articulate system architecture, as discussed in this paper can be implemented in the short term. Flexible AC transmission systems which are now undergoing rapid development and implementation, can be regarded as a subset of the family of control methodologies which constitute the realm of articulate systems.Publication Power converters as natural gyrators(IEEE, 1993-12) Ehsani, Mehrdad; Husain, Iqbal; Bilgiç, Mehmet Oruç; 1616The authors investigate the open-loop gyrator behavior of a class of DC-DC converters that are characterized by double bridges. If the switching frequency of the double bridge converter is high enough with respect to its natural frequencies, the converter can be viewed as a gyrator from its terminals. Unlike other gyrator modeling approaches for converters, the double bridge converters naturally behave as gyrators without any extra control circuits.Publication Topological Variations of the Inverse Dual Converter for High Power DC-DC Applications(IEEE, 1990-10-07) Ehsani, M.; Laskai, L.; Bilgiç, Mehmet Oruç; 1616DC to DC power converter topologies that are suitable for high-density, high-power supplies are presented. Topological variations on the basic inverse dual converter (IDC) circuit, such as the coupled transformer and the multiphase and multipulse derivation of the single-phase IDC, are analyzed, and simulation results are discussed. The topologies have most of the IDC features, such as buck-boost operation, bidirectional power processing, capacitive commutation for switches, and unlimited high-power capability. The multiphase, the coupled transformer, and the power distribution IDC topologies offer additional properties, such as significant power-density improvement isolation. AC tapping, and input-current reduction. A quantitative comparison between the single- and the multiphase IDC is presented.Publication Yürüme esnasındaki gövde-baş açısı ölçümü için kablosuz çift ivmeölçerli giyilebilir sistem(IEEE, 2018) AKALAN, NAZİF EKİN; GÜRKAN, GÜRAY; ÖNERGE, KÜBRA; 113297; 283338; 176320Literatürde, yere bakarak yürümenin yürüme parametrelerini ve ayak basıncını değiştirebileceği ile ilgili bilindik bir çalışma bulunmamaktadır. Bu çalışmada, yürüme esnasında gövde-baş açı değişimini ölçebilen bir sistem sunulmaktadır. Sistemin donanım kısmı, oksipital ve sırt bölgelerine yerleştirilen iki adet 3 eksenli sayısal ivmeölçer, mikroişlemci, Bluetooth modülü ve bataryadan oluşmaktadır. Mikroişlemcinin aldığı ivme verisi Bluetooth aracılığı ile alıcı bilgisayara gönderilmektedir. Verinin alınması, açı kestiriminin yapılması ve görselleştirilmesi, sistemin yazılım kısmını oluşturan ve Python dilinde geliştirilen kullanıcı arayüzü ile yapılmaktadır. Geliştirilen sistem hem iki serbestlik dereceli bir kol üzerinde hem de yürüme sırasında bir kullanıcı üzerinde test edilmiştir.