1,720,989 research outputs found
Double Modulation Converter
Get PDFThe Double Modulation Converter (Dmc) Is A Dc-Ac Converter For Driving An Ac-Dc Converter. It Has Two Input Terminals For Connection To A Dc Voltage Source, Two Output Terminals For Connection To An Ac-Dc Converter, And A Plurality Of Circuit Control Terminals For Receiving A Plurality Of Control Waveforms Which Cause A Bipolar Stream Of Width- And Amplitude-Modulated Pulses To Appear At The Output Terminals When A Load Is Connected Across The Output Terminals. The Basic Elements Of The Dmc Are Two Switches Connected In Series Across The Input Terminals. One Output Line Connects An Output Terminal To The Junction Of The Two Switches. The Other Output Line Connects The Other Output Terminal To One Of The Input Terminals. During Operation, The Two Switches Periodically And Alternately Open And Close, The Closure Of One Switch Causing A Pulse Of One Polarity To Appear Across The Output Terminals, And The Closure Of The Other Switch Causing A Pulse Of Opposite Polarity To Appear Across The Output Terminals. A Switch Is Closed Only When A Near-Zero Voltage Exists Across The Switch. In Order To Bring About This Result, A Diode And Capacitor Are Connected In Parallel With Each Switch And An Inductor Is Placed In Output Line. When One Switch Opens, The Other Switch Closes Only When There Is Less Than 0.7 Volts Across The Switch. The Time Period During Which The Voltage Across The Switch To Be Closed Is Less Than 0.7 Volts Is A Function Of The Resonant Frequency Of The Capacitance Associated With The Switch To Be Closed And The Inductance Associated With The Output Lines And The Load To Which The Output Lines Are Connected. One Or More Capacitors Are Placed In One Of The Output Lines To Block Dc. The Resonant Frequency Of The Output-Line Capacitors And Inductor Is At Least A Factor Of Two Less Than The Switching Frequency.published_or_final_versio
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
Capacitor Coupled Converter
Get PDFThe Capacitor Coupled Converter (Ccc) Is A Dc-Dc Converter Which Produce A Dc Source As The Output. It Has Two Input Terminals For Connection To A Dc Voltage Source, Two Output Terminals For Connection To A Load, And A Plurality Of Circuit Control Terminals For Receiving A Plurality Of Control Waveforms. The Basic Elements Of The Ccc Are Two Switches Connected In Series Across The Input Terminals. An Inductor In Series With A Transformer Is Connected To The Junction Of The Two Switches. Two Capacitors With Parallel Diodes Are Connected Across The Input Dc Voltage Source. The Junction Between The Two Capacitors Is Connected To One Of The Primary Terminal Of The Transformer. The Secondary Terminals Of The Transformer Is Connected To An Ac-Dc Converter, Typically Two Diodes Which Rectify The Ac To Dc. The Dc Is Then Filtered By An Inductor-Capacitor Filter. During Operation, The Two Switches Periodically And Alternately Open And Close. The Two Capacitors Across The Input Terminals Are Charged And Discharged Alternately By A Current Through The Primary Circuit. Triangular Waveform Is Produced Across The Transformer Which Transfer Power To The Output. The Power Output Is Limited Inherently By The Charging Process. The Ccc Also Enables Zero Voltage Switching. A Switch Is Closed Only When A Near-Zero Voltage Exists Across The Switch. In Order To Bring About This Result, A Diode And Capacitor Are Connected In Parallel With Each Switch. When One Switch Opens, The Other Switch Closes Usually When There Is Less Than 0.7 Volts Across The Switch. The Time Period During Which The Voltage Across The Switch To Be Closed Is Less Than 0.7 Volts Is A Function Of The Resonant Frequency Of The Capacitance Associated With The Switch To Be Closed And The Inductance Associated With The Primary Circuit. Zero Voltage Switching Reduce Loss Associated With The Switches.published_or_final_versio
Family Of Zero Voltage Switching Dc To Dc Converters With Coupled Output Inductor
Get PDFA Family Of Power Converter Is Invented. Each Of These Converter Accomplishes Zero Voltage Switching To Minimize Switching Losses. Also By The Application Of Coupled Inductor, Conduction Losses Can Also Be Minimized. The Basic Embodiment Comprises Of Two Switches Connected Across The Input Source. The Switches Are Driven By Asymmetrical Driving Pulses With Variable Duty Cycle. A Capacitor Is Connected To The Node Joining The Two Switches And An Inductor Is In Turn Connected To It. This Inductor Is Connected To An Output Filter Through A Diode. The Output Filter Comprises Of An Inductor And Capacitor And Diode Combinations. This Output Filter Inductor Has Two Coupled Windings Which Minimize Conduction Losses. The Basic Embodiment Can Be Modified To Provide Converter With Boost Output Or Negative Output. The Embodiment Can Also Be Modified For Isolated Converter With Transformer In Both Half Bridge And Full Bridge Circuit.published_or_final_versio
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
High Efficiency Driver For Color Light Emitting Diodes (Led)
Get PDFAn Efficient Power Driver For Color Light Emitting Diodes (Led) Is Disclosed For Driving Multiple Leds For Producing Different Desired Colors. Such Led Combinations Comprising Leds With Different Primary Colors Are Suitable For Implementing Pixels In Displaying A Digitized Image. This Disclosed Invention Provides Switching Power Conversion Embodiments Such That A Single Apparatus Drives Different Color Leds. Furthermore, The Disclosed Invention Provides Configurations With And Without Input To Output Isolation While Enabling Control Of The Current Through Each Led, For Instance By An Inductor Or Operating Condition.published_or_final_versio
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