1,720,970 research outputs found
Herstellung und Charakterisierung von Lithiumlanthanzirkonat-Funktionsschichten für Lithium-Festkörperbatterien
No full textThe aim of this work is to produce a lithium ion conducting solid electrolyte as basic material for application in new efficient energy storage such as solid state batteries. If the liquid electrolyte in lithium ion batteries (LIB) is replaced by a self-supported solid electrolyte, safety, durability and energy density can be improved. Tape casting is a suitable method to process aforementioned self-supported solid electrolytes. The focus is on the powder synthesis of lithium lanthanum zirconate (LiLaZrO;LLZO)which can be optimized by substitution with elements like Al, Ta or Y. These substituted LLZO compositions show improved mechanical and (electro-) chemical stability, and have the highest lithium ion conductivity for all oxide electrolytes. Furthermore, a comparison between the synthesis by solid state reaction and by spray pyrolysis is made. In respect of the influence of process parameters, the microstructure, mechanical properties and the ionic conductivity of sintered pellets are examined. Spray pyrolysis has proved to be a scalable method which was used to synthesize Al-LLZO in a purely cubic phase. Moreover, in this work it is shown that Ta-LLZO has the most suitable cross-section profile in matters of sinterbility, the mechanical properties (hardness and elastic modulus) and lithium ion conductivity. Another main focus is the characterization of LLZO’s crystal structure. Several LLZO electrolytes have been sintered in an air or an argon atmosphere and were subsequently examined by complementary characterization methods in the context of a cooperation with the (ORNL). Next to the crystal structure, especially the atomic positions as well as the occupancies of lithium were determined for several LLZO compositions. A water-free synthesis of LLZO powders was proven by inelastic neutron scattering and in addition, a lithium-proton exchange was prevented. Furthermore, neutron backscattering is used to determine LLZO’s self-diffusion constants and related activation energies. Thus, it could be shown that the tetragonal LLZO phase doesn’t contribute significantly to lithium ion’s self-diffusion. Spray pyrolyzed Al-LLZO was used for a tape casting slurry’s development. A defect-free thin electrolyte film was cast and used for sintering experiments. The microstructure of sintered solid state electrolytes still is not sufficient for a self-supported solid electrolyte. Though, a promising candidate for continuing tape casting is tantalum substituted LLZOsynthesized by spray pyrolysis. Its suitable particle size distribution and sinterbility enable the fabrication of self-supported LLZO functional layer for solid state lithium ion batteries
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
Navigating the power shift : a comparative study of electricity grid remunicipalization in medium-sized German cities
No full textBack to the future? : An analysis of party influence on electricity grid remunicipalisation in Germany
No full textLocal-level ownership of electricity grids : an analysis of Germany's distribution system operators (DSOs)
No full textElectricity grids are crucial for the energy transition. Despite its importance for renewable energy, the literature on grid ownership at the local level in Germany lacks up-to-date knowledge. Existing research does not state the extent to which municipalities own distribution system operators (DSOs). Based on a novel dataset on grid operators in 10,800 German municipalities, this paper can provide for the first time an overview of the current ownership of electricity distribution companies. Although the electricity infrastructure is decentralised, ownership remains centralised in the hands of Germany's leading energy companies and concentrated in affluent population centres
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