1,720,994 research outputs found
Wireless Telemetry for Characterization and Design of In-tire Piezoelectric Energy Harvesting Systems
Full text linkThe design of new a generation of smart tyre sensors directly powered by tyre motion, requires accurate information about electrical quantities related to electromechanical energy harvesters in realistic operating conditions. Transducers and circuits are not accessible inside tyres, and it is difficult to predict theoretically or numerically their behaviour. This paper presents a characterization methodology for energy harvesters in tyres based on wireless telemetry and on a series of specific measurements performed in an industrial-grade tyre test machine. A Wi-Fi modular telemetry platform is designed for acquiring inside tyres, at up to 14 kSa/s, open-circuit voltages up to ±160 V, and short-circuit currents up to ±18 mA, from piezoelectric transducers. A power estimation technique is executed locally to extract static power transfer characteristics. Measurements were performed in real-world conditions on commercial tyres in an industrial drum test machine operated at controlled speeds up to 40 km/h and axial loads up to 3 kN. Among its contributions, the paper analyzes the in-tyre behaviour of piezoelectric harvesters in terms of voltage, current, and power, and reports reference data from a relevant test environment to support power converter circuit design. To characterize joint in-tyre and energy-autonomous operation of piezoelectric transducers, power management circuits, and tyre sensors, fully functional electronic systems are validated on-field by the proposed telemetry platform. Validated circuits include passive rectifiers and synchronous electric charge extractors
ORGANOMETALLIC SYNTHESIS VIA SURFACE-MEDIATED REACTIONS - HIGH-YIELD ROUTE TO HOS3(CO)10(OH)
No full textAn integrated DC/DC converter with online monitoring of hot-carrier degradation
Full text linkAn integrated DC/DC converter with online monitoring of the degradation induced by hot-carrier stress (HCD) in new generation power LDMOS transistors is proposed. In particular, when a relatively high drain voltage is applied during on-state regime (switching phase), degradation mechanisms lead to an increase of the transistor on-resistance (RON). To this purpose, the converter is able to dynamically estimate the RON of the power LDMOS and to provide its value to the user during normal operation. The presented solution, developed in STMicroelectronics 90nm BCD technology, features a non-invasive current sensing and voltage sampling architecture, which is applied to a common DC/DC boost converter to evaluate the resistance of the power LDMOS. Without lack of generality, this specific sensing structure can be applied to any kind of converter, e.g. buck or buck-boost, as it does not require any change in the main conversion circuit
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
CATALYSIS BY PALLADIUM SALTS: THE REDUCTIVE CARBONYLATION OF NITROAROMATIC COMPOUNDS TO ISOCYANATES WITH PDII AND PD0 COMPLEXES AS HOMOGENEOUS CATALYSTS
No full textA ‘donor-free’ chromophore with a silicon-based acceptor group for second order nonlinear optics
No full textIn this paper we report an investigation on the linear and nonlinear properties of a non-classic push-pull molecule, based on the molecular design concept of a ‘donor-free’ chromophore. Herein a terthiophene unit acts both as a donor and a π-spacer group and a tris(trimethylsiloxy)silane substituent as an acceptor group. This latter can represent a model of a fragment of silica surface and it has been compared with a classic acceptor unit like the nitro group. The ‘donor-free’ chromophores have also been compared to more typical push-pull chromophores by replacing the terthiophene unit with the N,N-dimethylamino donor group. Despite the silane group only slightly impacts on the electronic and linear properties of the terthiophene, our results reveal high μβEFISH values for silane-functionalized derivatives producing a NLO activity stronger than that of the nitro substituted. Finally, the investigated ‘donor-free’ NLO-phore exhibits interesting physical properties relevant in term of nonlinearity/transparency trade-off, a highly desired requirement for second-order NLO materials
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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