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Merjenje in modeliranje močnostnih SiC MOSFET tranzistorjev
Get PDFThe increasing demand for smaller, faster, and more efficient switch mode power supplies (SMPS) and energy converters has led to the development of new power MOSFET technologies, such as SiC (silicon carbide) power MOSFET transistors. Switching parameters, output voltages and currents and power consumption need to be measured accurately to assess different types of power electronics components more efficiently in today’s rapid implementation of new energy transfer and modulation technology. The need for improving switching circuits in power electronics and trying to use simple simulation circuits for designing PCBs to measure output values of said power electronics transistors is the basis of this thesis. Even though manufacturers of power electronics transistors provide data on drain-source voltages and currents, these are mostly measured for specific conditions regarding pulse duration, gate-source voltage, case temperature of the transistor etc., and as such do not provide information as to where the limits of the drain source voltages and currents for different measurement parameter values are. The goal of the thesis is to find a way to measure the limits of drain-source voltages and currents of power electronics transistors (in this case a SiC MOSFET transistor), and to see if a simple SPICE-model could be built for other power electronic transistors as well, based on the results of this thesis.Na področju močnostne elektronike je bilo v zadnjih tridesetih letih večje povpraševanje po hitrejših in močnejših MOSFET tranzistorjih. Ena izmed vrst MOSFET tranzistorjev, ki ustreza tem zahtevam, temelji na tehnologiji SiC ali silicijevem karbidu. SiC MOSFET tranzistorji imajo prihodnost v razvoju električnih vozil, procesih pretvorbe in prenosa energije in še veliko več. Primerni so za visoke napetosti in tokove pri visokih preklopnih frekvencah in tako ustvarjajo zelo majhne izgube. Merjenje preklopnih parametrov pomaga pri razvoju naprednejših vezi na osnovi SiC MOSFET tranzistorjev, zasnovanih za izvedbe velike moči in visoke hitrosti. Da bi ugotovili meje delovanja te vrste tranzistorjev med preklapljanjem, je potrebno narediti elektronsko vezje, ki lahko dovolj natančno merijo pomembne preklopne parametre. Obstoječe merilne nastavitve so zasnovane za merjenje izhodnih vrednosti SiC MOSFET tranzistorjev z uporabo zaporednih kratkih pulzov. Delo se osredotoča na merjenje teh vrednosti znotraj enega, čim hitrejšega pulza, in na merjenje meja teh vrednosti pri različnih temperaturah ohišja tranzistorja in različnih napetosti drain-source. Cilj magistrskega dela je ustvariti simulacijo na osnovi modela SiC MOSFET tranzistorja, analizirati obnašanje simulacije med preklopom z enim pulzom in nato na podlagi simulacije zgraditi evalvacijsko tiskano (elektronsko) vezje. Pomembno je analizirati vedenje elektronskega vezja, kako se ga primerja s simulacijskim modelom in kako natančni so rezultati simulacije v primerjavi z meritvami, izvedenimi na tiskanemu vezju. Na koncu bodo izmerjene meje tokov drain-source pri različnih temperaturah ohišja SiC MOSFET tranzistorja, pridobljene podatke pa bomo primerjali s simulacijo. Zaključek o tem, kako dobro je simulacija predstavljala elektronsko vezje in kako dobro so bile zastopane meritve v primerjavi s podatki proizvajalca, bo predstavljal oblikovan in izdelan simulacijski načrt, ki bo služil kot osnova za načrtovanje tiskanega vezja ki uporablja različne tranzistorje močnostne elektronike
Ekološki i ekonomski efekti razvoja tržišta električnih automobila u Republici Hrvatskoj
No full textElektrični automobil je cestovno vozilo koje ima povijest koja je duža od 100 godina, a posljednjih desetljeća bilježi veliki rast prodaje. Brzom razvoju tržišta električnih automobila najviše doprinosi globalno zagađenje okoliša, rast cijene nafte te sve veća osviještenost korisnika o očuvanju okoliša. Republika Hrvatska dio je globalnih trendova u kojoj se povećava broj električnih vozila. Ipak Hrvatska ima brojne specifičnosti kao što su maleno tržište, niska kupovna moć i nedovoljno razvijena infrastruktura. Uz pomoć Europske unije, vlada i druga državna tijela potiču rast prodaje električnih vozila te usporedno s razvojem tržišta ulažu znatna sredstva u infrastrukturu, ali i istraživanje i razvoj. Primjerice, broj prodanih električnih automobila u Hrvatskoj se u razdoblju od 2013. do 2018. godine povećao gotovo dvadeset puta. Tijekom 2018. godine prodano je ukupno 452 novih električnih automobila što su male brojke u usporedbi sa Norveškom gdje je u 2019. godini broj prodanih električnih automobila nadmašio broj benzinskih i dizelskih. Unatoč državnim poticajima, električni automobil i dalje nije isplativ za prosječnog korisnika. Analizom je utvrđeno da za korisnike koji prelaze natprosječnu kilometražu, električni automobil može postati isplativ već nakon 5 godina. Električni automobili tijekom korištenja ne ispuštaju CO2 u atmosferu, ali prilikom analize ukupnog utjecaja na okoliš bitno je uzeti u obzir proizvodnju električne energije. Trenutno se u Republici Hrvatskoj velik dio električne energije proizvodi korištenjem izvora koji su opasni za okoliš, i dalje se 28% električne energije proizvodi iz fosilnih goriva te je primjetan veliki udio neekoloških termoelektrana, no vidljiv je trend ulaganja u obnovljive izvore energije
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
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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