1,721,405 research outputs found
Perovskite ruthenate-based lead free thick film resistores
No full textAs well Know, the dielectric matrix of air-fireable thick-film resistors(TFRs) presently used in hybrid microelectronics and passive components invariably consists in hifh-lead silicate glass. However the actual trend is to restrict and possibly eleiminate Pb from electronic components. Attempts to develop suita. RuO2-based or pyrochlore ruthenate-based Pb-Cd free TFRs has been only partiallt successful till now. We report here the preliminary results of a study aimed to investigate the flexibility of CaRuO3 perovskite-based lead-free TFRs. The results show that sheet resistances larger than 1 KOhm/square cab be easily achieved in a controlled way, with hot temperature coefficient of resistance in the the range of a few hundreds ppm/deg.C. In addition, the resistors do not exhibit negative structural features, like bleeding or devitrification, observed in previous attempts to develop reliable lead-free TFRs
Environment friendly perovskite ruthenate based thick film resistors
No full textIt is well known that the dielectric matrix of air-fireable thick film resistors (TFRs) presently used in hybrid microelectronics and passive components invariably consists of a high-lead silicate glass. However, the current trend in the electronic industry is to restrict and eliminate the hazardous elements viz. lead, cadmium etc. from electronic components. An attempt to develop suitable RuO2-based or pyrochlore ruthenate based Pb-Cd free TFRs has been only partially successful till now. We report here the preliminary results of a study aimed to investigate the feasibility of CaRuO3 perovskite-based lead-free TFRs. Our results showed that sheet resistances higher than 1 k Omega/sq. can be easily achieved in a controlled way, with hot and cold temperature coefficients of resistance (TCR) in the range of 325-580 ppm/degrees C and 180-500 ppm/degrees C, respectively. Similarly, the compositions also exhibit negligible piezoresistive effects with gauge factor, GF < 1. Additionally, the resistors do not exhibit negative structural features, like bleeding or devitrification of glass, observed in previous attempts to develop reliable lead-free TFRs. (c) 2006 Elsevier B.V. All rights reserved
Structural and electrical properties of perovskite ruthenate-based lead-free thick film resistors on alumina and LTCC
No full textCaRuO3 perovskite-based lead-free thick-film resistors (TFRs) were prepared on 96%-alumina and Low Temperature Co-fired Ceramic (LTCC) substrates. The microstructure evolution, possible interactions, and electrical properties of resistors were investigated. The hot and cold TCR values of all the resistors were measured in the temperature range (+20 to +120 ° C) and (+20 to -120 ° C), respectively. TFRs with 25% by vol. of CaRuO3 on alumina exhibit a sheet resistance R-s = 5 k Ohm/sq. with hot and cold TCR of 225 and 470 ppm/° C respectively, whereas the same composition gives 1.2 k Ohm/sq., 16.5 k Ohm/sq. and 0.7 k Ohm/sq. for co-fired, post-fired resistors on LTCC and buried resistors, respectively. The hot (HTCR) and cold (CTCR) values were evaluated; HTCR = 190 ppm/° C and CTCR = 314 ppm/°C were found for co-fired structures; HTCR = 216 ppm/degrees C and CTCR = 205 ppm/°C for post-fired samples and HTCR = 520 ppm/°C and CTCR = 350 ppm/° C for buried in LTCC structures
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
Microstructure and elelectrical propperties of perovskite ruthenate-based lead free thick-film resistors on alumina and LTCC.
No full textCaRuO3, perovskite-based lead-free thick-film resstors were processed on 96%-alumina and Low Temperature Co-fired Ceramic (LTCC) substrates. The microstructure evolution, possible interaction and electrical properties of resistors were ivestigated. TFR with 25% by vol. of ruthenate on alumina exhibit a sheet resistance Rs=5 KOhm/sqwith hot and cold TCR of 225 and 470 ppm/degree C respectively, whereas the same composition gives 1.2 KOhm/sq and 16.5 KOhm/sq. for cofired and postfired samples, respectively, on LTCC, wuth hot and cold TCR of 190 and 314 ppm/degreeC for co-fired structures, and 216 and 250-ppm/degreeC for post-fired LTCC structires
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