1,720,977 research outputs found
Research and Development of Modular Uninterruptible Power Supply System with Varied Energy Sources and Storages
No full textŠī doktora disertācija ir veltīta uz universāliem spēka moduļiem (USM) veidotas modulāras nepārtrauktās barošanas bloka (NBB) sistēmas izstrādei. Darba novitāte un atšķirība no citiem jau eksistējošiem NBB moduļiem ir USM multifunkcionalitāte. Esošie NBB moduļi ļauj palielināt jaudu vai apvienot vairākus moduļus sistēmas drošuma palielināšanai. Ar USM palīdzību arī var izmantot tādus alternatīvās enerģijas avotus un uzkrājējus kā superkondensatorus, spararatus, kurināmā elementus, saules paneļus, vēja ģeneratorus un citus. Tirgū šobrīd ir pieejamas dažādu veidu NBB sistēmas. Dažas no tām nav paplašināmas. Dažas no tām var slēgt paralēli, lai palielinātu jaudu un drošumu. Dažas no tām izmanto tādus alternatīvos enerģijas uzkrājējus kā superkondensatorus un spararatus. Visattīstītākās NBB sistēmas pat var pārslēgties starp darbības režīmiem(dubultās pārveidošanas režīms vai mijiedarbības ar tīklu režīms), lai uzlabotu lietderību vai palielinātu drošumu. Disertācijā pētītā modulārā NBB sistēma apvieno lielāko daļu iepriekš minēto funkciju.
Ar to var:
-izveidot invertorus, aktīvos taisngriežus, līdzstrāvas pārveidotājus;
-izveidot dažādas NBB topoloģijas, piemēram, “NBB ar pārslēgšanos”, “dubultās pārveidošanas NBB”, “līdzstrāvas NBB”;
-izmantot tādus enerģijas uzkrājējus kā superkondensatorus un spararatus;
-izmantot tādus enerģijas avotus kā saules paneļus, vēja turbīnas, kurināmā elementus;
-izveidot NBB sistēmas priekš attālinātām vietām, kur nav pieejams tīkla spriegums, bet ir pieejami alternatīvie enerģijas avoti;
-veidot spēka pārveidotājus, kurus viegli pārveidot par citām sistēmām.
Pirmajā nodaļā ir aprakstītas tīkla problēmas. Ir dots īss NBB topoloģiju apraksts. Ir aprakstīti arī NBB sistēmās izmantojamie enerģijas avoti un uzkrājēji. Pirmās nodaļas beigās ir doti iemesli modulārās sistēmās izmantošanai.
Otrajā nodaļā ir aprakstītas USM izstrādes stadijas.
Trešajā nodaļā ir aprakstīta Matlab-simulink modeļu izstrāde priekš USM un tā vadības algoritmiem.
Ceturtajā nodaļā ir apskatīti modelēšanas un eksperimentālie pierādījumi iespējamajai USM izmantošanai NBB sistēmu veidošanā.
Pēdējā nodaļā ir aprēķinātas USM un ar USM veidotas NBB sistēmas izmaksas.
Disertācija ir rakstīta angļu valodā. Tā satur: 190 lapaspuses, ievadu, 5 nodaļas, secinājumus, 190 attēlus, 72 formulas, 29 tabulas, 68 literatūras avotus un 4 pielikumus
Модульная система бесперебойного питания с альтернативными накопителями и источниками энергии
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Power Line Communication with High Frequency Impedance Modulation for Battery Management
No full textIn the paper a power line communication system for series connected devises like batteries, supercapacitors or other voltage sources is proposed. The communication is based on high frequency current amplitude modulation in one direction (from master to slaves) and on impedance modulation in another direction (from slaves to master). The proposed system provides an excellent opportunity to realize battery monitoring and management without additional wires between cells and main battery management block
Development of Supercapacitor Based Uninterruptible Power Supply
No full textThe given paper deals with uninterruptible power supplies utilizing supercapacitors (ultracapacitors). Different types of supercapacitor are described. Various opportunities of supercapacitor implementation are discussed, pros and cons are compared. Experimental comparison of lead-acid battery with supercapacitor is done
Selection of Inverter Topology for Uninterruptible Power Supply System
No full textВ этой статье проводиться анализ инверторов напряжения в связи с разработкой системы бесперебойного питания. Полномостовая и полу-мостовая схемы инверторов проанализированы, промоделированы и одна из них экспериментально проверена. Даны рекомендации для будущей работы
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
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