1,720,998 research outputs found
A 74%, 1.56-2.71 GHz, wide-tunable LC-tuned VCO in 0.35-mu m CMOS technology
No full textA wide-tuning monolithic LC-tuned VCO is presented. The proposed VCO wide, tuning hi utilizing binary weighted switched varactor combination operating at minimum or maximum value in addition to a linearly varying interpolation varactor. Measurements show 74% of tuning at it range of 1.56-2.71 GHz. with the phase noise ranging from -136 dBc/Hz to -108 dBc/Hz at 1 MHz offset. The VCO is implemented in 0.35-mum CMOS technology and dissipates 10.3 mA from a 3-V supply. (C) 2003 Wiley Periodicals, Inc
Failure modes of silicon powder negative electrode in lithium secondary batteries
No full textSi composite negative electrodes for lithium secondary batteries degrade in the dealloying period with an abrupt increase in internal resistance that is caused by a breakdown of conductive network made between Si and carbon particles. This results from a volume contraction of Si particles after expansion in the previous alloying process. Due to the large internal resistance, the dealloying reaction is not completed while Si remains as a lithiated state. The anodic performance is greatly improved either by applying a pressure on the cells or loading a larger amount of conductive carbon in the composite electrodes. (C) 2004 The Electrochemical Society.Y
Electric double-layer capacitor performance of a new mesoporous carbon
No full textA new mesoporous carbon (NMC) was prepared, and its performance in an electric double-layer capacitor (EDLC) was compared to that of a conventional carbon (a molecular-sieving carbon, MSC25). The effect of pore size and pore connection pattern on EDLC performance was demonstrated. To prepare NMC, phenol resin was synthesized inside the pores of an inorganic template, Mobile Composite Material 48 (MCM48), and the resulting resin-template composite was carbonized at 700 degrees C under Ar atmosphere. A coke-like carbonaceous material was obtained after removing the inorganic template by HF treatment. The surface area of NMC was 1257 m(2) g(-1) which is smaller than that of MSC25 (1970 m(2) g(-1)). NMC had three-dimensionally interconnected mesopores (2.3 nm average diam), but randomly connected cage-like micropores (<2.0 nm) were dominant in MSC25. The difference in the pore size and pore connection pattern between the two carbons gave rise to a remarkable difference in their EDLC performances. NMC exhibited a smaller specific capacitance (about 120 F g(-1)) than MSC25 as a result of its smaller surface area, but it showed a higher critical scan rate than the MSC25 electrode due to a smaller resistance-capacitance (RC) time constant. The specific charging capacity of the NMC electrode was about 20 mAh g(-1) and was largely invariant vs. the charge-discharge rate. This was contrasted by MSC25 which showed a steadily decreasing capacity with an increase in rate. As a result, the NMC electrode outperformed the MSC25 based on rate capability. The smaller RC time constant and better rate capability of the NMC electrode apparently arises from the lower electrolyte resistance in pores, which in turn stems from the faster ionic motion in larger pores. (C) 2000 The Electrochemical Society. S0013-4651(00)01-080-6. All rights reserved.
Synthesis of a new mesoporous carbon and its application to electrochemical double-layer capacitors
No full textA mesoporous carbon with regular three-dimensionally interconnected 2 nm pore arrays using AlMCM-48 as a template has been synthesised; the mesoporous carbon exhibited excellent performance as an electrochemical double layer capacitor.
Broadcast Signal Transmission Employing Low Noise Mutually Injected Fabry-P?rot Laser Diodes
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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