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Rezonans Devreli ve Yumuşak Anahtarlamalı Yeni Bir Tek Aşamalı PFC Devresinin Geliştirilmesi ve Gerçekleştirilmesi
No full textYüksek Güç Faktörlü Şebeke Bağlı Bir PV Sistemin Modellenmesi ve Farklı Işınımlar Altında Kontrolü
No full textGünümüzde gelişen teknolojiye bağlı olarak enerji tüketimi hızla artmakta, buna karşılık enerji kaynakları hızla tükenmektedir.Elektrik enerjisinin üretiminde kullanılan kömür, doğalgaz ve uranyum v.b. yenilenemeyen kaynaklarının kurulumu zordur. Aynızamanda karbon içeriğine sahip olmaları sebebiyle çevre kirliliğine ve küresel ısınmaya yol açmaktadır. Böylece, güneş ve rüzgar gibiyenilenebilir enerji kaynaklarının kullanımına olan ilgi gün geçtikçe artmaktadır. Özellikle, güneş enerjisinin her daim var olan birenerji olması sebebiyle daha çok tercih edilmektedir. Güneşten elde edilen enerji ışınıma, panel sıcaklığına ve kirliliğine bağlı olarakdeğişebilmektedir. Güneş panellerinin çıkışındaki gerilim ve akım arasında nonlineer bir ilişki bulunmakta ve güneşten elde edilengüç sürekli değişmektedir. Bu sebeplerden dolayı, bir güneş panelinden maksimum enerji çekmek üzere Maksimum Güç NoktasıTakibi (MGNT) algoritmaları geliştirilmektedir. Bu algoritmalar arasında en yaygın ve uygulaması en kolay olan Sars ve Gözlemle(S&G) metodudur. Bu çalışmada, yüksek güç faktörlü şebeke bağlı bir PV sistemin modellenmesi ve farklı ışınımlar altında kontrolüile şebekeye etkileri incelenmiştir. Sunulan PV sistemi, yükseltici tür dönüştürücü ile tam köprü tür inverterin birleştirilmesi ileoluşturulmuştur. Sistemin girişinde, istenilen güç ve gerilimi sağlamak üzere PV paneller seri olarak bağlanmıştır. Yükseltici türdönüştürücü, S&G algoritması ile çalıştırılarak MGNT sağlanmaktadır. Aynı zamanda inverter, Ortalama Akım Mod Kontrol(OAMK) yöntemi ile çalıştırılarak, şebekeye yüksek Güç Faktörü (GF) ile akım verilmesi sağlanmaktadır. Burada her iki devre deanalog olarak kontrol edilmektedir. Bu amaçla, 1 kW gücü ve 100 kHz anahtarlama frekansına sahip şebeke bağlı bir PV sistemkurularak, PSIM programı ile simülasyonu gerçekleştirilmiştir. Geliştirilen sistemde 250 W-1000W/m2ışınım özelliklerine sahip 4 eşpanel seri bağlanmıştır. Farklı ışınım ve güç değerleri altında sistem çalıştırlarak, sistemin kontrolü ile şebeke etkileri incelenmiştir.Elde edilen sonuçlarda farklı koşullar altında hedeflenen sistemin, ilgili kontrol algoritmalarına bağlı olarak hızlı dinamik cevapverme süresine sahip olduğu ve şebeke tarafında her daim yüksek GF elde edildiği gözlemlenmiştir.</p
İnverterler İçin Yeni ve Modüler Bir Aktif Bastırma Hücresinin Geliştirilmesi ve Uygulanması
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Axial Flux Permanent Magnet Motor Design for Lightweight Unmanned Aerial Vehicles
No full textAxial flux permanent magnet (AFPM) motors are a type of electric motor in which the magnetic flux between the stator and rotor flows in the axial direction. These motors show superior performance compared to radial flux permanent magnet (RFPM) motors in industrial applications such as fans, industrial pump systems, and automotive industry, due to their ability to operate at high speeds, high-power density, and low flux path features. Nowadays, unmanned aerial vehicles (UAVs) are used in various fields such as mapping, firefighting, logistics, and military fields. High-efficiency, low-weight, and cost-effective motors have been gaining attraction for UAVs. In this paper, an AFPM is designed to achieve high-power density and efficiency in UAV applications. At the design stage, the essential flowchart and the equations used to calculate the dimensions of the AFPM motor are presented. Based on the presented equations, a three-phase axial flux motor simulation is carried out using the Ansys Electronics Desktop software, with a nominal power of 1 kW and a power density of 2.97 W/g, which can be used between 0-12500 rpm. The proposed design procedure is verified with the simulation results using finite element analysis.</p
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
A comparasion of the effects of different commutation techniques on acoustic noise in AFPM UAV motors
No full textPMSM and AFPM are two different types of permanent magnet motors that convert electrical energy into mechanical energy and are used in many industrial applications. These motors are ahead of other motor types, especially in terms of energy efficiency and power density. In unmanned aerial vehicles, it is a great advantage to use a low weight and low volume propulsion provider. Moreover, the low level of acoustic noise is important for UAVs. In this paper, a new coreless AFPM (C-AFPM) was designed, and the prototype was carried out to achieve low acoustic noise. The acoustic performance of six-step and FOC commutation techniques was observed. As a result, it has been seen that an AFPM driven with the FOC control technique emits around 30% lower acoustic noise than the scenario driven by the six-step technique with the new C-AFPM machine for UAVs
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Comparison of Increasing Efficiency in DAB Converters using EPS, DPS and TPS with Evolutionary Algorithms
No full textDual Active Bridge (DAB) converters are widely used in energy storage systems and electrical vehicle applications due to providing isolation and bidirectional power flow. However, recycling energy causes additional losses and minimum efficiency. So, there are phase shift control techniques to minimize recycling energy and increase efficiency. In this paper, nature-inspired evolutionary algorithms which are Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) are used to determine the optimum phase shift ratios in search space
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