1,720,982 research outputs found
Scale-up of milling in a 100 liter device for processing of TiFeMn alloy for hydrogen storage applications: procedure and characterization
Get PDFIn this work, the mechanical milling of a FeTiMn alloy for hydrogen storage purposes was performed in an industrial milling device. The TiFe hydride is interesting from the technological standpoint because of the abundance and the low cost of its constituent elements Ti and Fe, as well as its high volumetric hydrogen capacity. However, TiFe is difficult to activate, usually requiring a thermal treatment above 400 °C. A TiFeMn alloy milled for just 10 minutes in a 100 liter industrial milling device showed excellent hydrogen storage properties without any thermal treatment. The as-milled TiFeMn alloy did not need any activation procedure and showed fast kinetic behavior and good cycling stability. Microstructural and morphological characterization of the as-received and as-milled TiFeMn alloys revealed that the material, presents reduced particle and crystallite sizes, even after such short time of milling. The refined microstructure of the as-milled TiFeMn is deemed to account for the improved hydrogen absorption-desorption properties.Fil: Bellosta von Colbe, José. Helmholtz–Zentrum Geesthacht. ; AlemaniaFil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Capurso, Giovanni. Helmholtz–Zentrum Geesthacht. ; AlemaniaFil: Franz, Andreas. ZoZ GmbH; AlemaniaFil: Ulrich Benz, Hans. ZoZ GmbH; AlemaniaFil: Zoz, Henning. ZoZ GmbH; AlemaniaFil: Klassen, Thomas. Helmholtz–Zentrum Geesthacht. ; AlemaniaFil: Dornheim, Martin. Helmholtz–Zentrum Geesthacht. ; Alemani
Designing an Ab2-type alloy (TIZr-CrMNMO) for the hybrid hydrogen storage concept
Get PDFThe hybrid hydrogen storage method consists of the combination of both solid-state metal hydrides and gas hydrogen storage. This method is regarded as a promising trade-off solution between the already developed high-pressure storage reservoir, utilized in the automobile industry, and solid-state storage through the formation of metal hydrides. Therefore, it is possible to lower the hydrogen pressure and to increase the hydrogen volumetric density. In this work, we design a non-stoichiometric AB2 C14-Laves alloy composed of (Ti0.9Zr0.1)1.25Cr0.85Mn1.1Mo0.05. This alloy is synthesized by arc-melting, and the thermodynamic and kinetic behaviors are evaluated in a high-pressure Sieverts apparatus. Proper thermodynamic parameters are obtained in the range of temperature and pressure from 3 to 85 ◦C and from 15 to 500 bar: ∆Habs. = 22 ± 1 kJ/mol H2, ∆Sabs. = 107 ± 2 J/K mol H2, and ∆Hdes. = 24 ± 1 kJ/mol H2, ∆Sdes. = 110 ± 3 J/K mol H2. The addition of 10 wt.% of expanded natural graphite (ENG) allows the improvement of the heat transfer properties, showing a reversible capacity of about 1.5 wt.%, cycling stability and hydrogenation/dehydrogenation times between 25 to 70 s. The feasibility for the utilization of the designed material in a high-pressure tank is also evaluated, considering practical design parameters.Fil: Puszkiel, Julián Atilio. Helmholtz-zentrum Geesthacht; Alemania. Instituto de Investigaciones Energéticas de Cataluña; España. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Gerencia de Investigación Aplicada CAB. Departamento Fisicoquímica de Materiales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Bellosta von Colbe, José M.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Jepsen, Julian. Helmholtz-zentrum Geesthacht; Alemania. Helmut Schmidt University; AlemaniaFil: Mitrokhin, Sergey V.. Lomonosov Moscow State University; RusiaFil: Movlaev, Elshad. Lomonosov Moscow State University; RusiaFil: Verbetsky, Victor. Lomonosov Moscow State University; RusiaFil: Klassen, Thomas. Helmholtz-zentrum Geesthacht; Alemania. Helmut Schmidt University; Alemani
Hydrogen storage in light metal hybrides
No full textIn dieser Arbeit wurden mehrere Dotierungsverbindungen auf ihre Effektivität in der Katalyse der Natriumalanat De- und Hydrierung getestet. Das Mahlen, wodurch die dotierten Proben entstehen, wurde zu einem kontrollierbaren Prozess über die in situ Messung der Wasserstoffentwicklung. Eine Ein-Schritt Synthese von dotiertem NaAlH in der Hochdruckkugelmühle wurde entwickelt, was Proben mit verbesserten Eigenschaften lieferte. Eine automatisierte isobarische Zyklisieranlage wurde gebaut und programmiert. Sie erlaubte Langzeits- und Stabilitätsversuche sowie die Feststellung von Reaktionsgeschwindigkeitsmaxima für die Hydrierung bei bestimmte Temperaturen unter konstantem Druck. Die Rolle des Katalysators im Splitten von Wasserstoffmolekülen wurde schliesslich in Isotopenaustausch Experimenten beobachtet. sowie Wasserstoffaustausch zwischen Probe und Atmosphäre unter milden Bedingungen.Several doping substances were tested as to the effectiveness of the catalyst they yielded for the de- and hydrogenation of sodium alanate. The milling process through which the doped samples are synthesized was improved through the addition of a device to measure the hydrogen evolution in situ during milling. A single-step synthesis of doped NaAlH in a high pressure mill was developed, yielding samples with improved characteristics. An automatic isobaric cycling apparatus was built and programmed, which allowed stability experiments over a long period of time, as well as the identification of hydrogenation rate maxima at two different pressures. Finally, the role of the catalyst in the hydrogen molecule splitting reaction was observed in isotope exchange experiments, as well as hydrogen exchange between the sample bulk and the gas atmosphere under mild conditions
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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