1,721,008 research outputs found
Atomic Cluster Expansion for a General-Purpose Interatomic Potential of Magnesium
No full text<p>This collection contains files associated with Physical Review Materials. "Atomic cluster expansion for a general-purpose interatomic potential of magnesium" (2023) paper:</p><p>- ACE potentials for magnesium.</p><p>-Active set inverted (ASI) for the ACE potential</p><p>- Magnesium DFT-PBE dataset computed with FHI-aims and that was used for fitting Atomic Cluster Expansion potential for magnesium.</p>
Bond order potentials for bcc transition metals and molybdenum silicides
No full textOne of the most challenging areas in materials science is modeling of the mechanical behavior of materials. Macroscopic properties, such as plastic flow and brittleness, are determined by processes occurring at the atomic level and are mainly influenced by the properties of extended defects. Understanding the energetics and structural properties of dislocations, grain boundaries and other extended defects enables to gain a valuable insight into the deformation mechanisms and allows to design specific ways to overcome intrinsic limitations of materials. In this thesis, we study the properties of extended defects in four bcc transition metals—Nb, Ta, Mo and W, using the bond order potentials (BOP). These potentials are based on the real-space parameterized tight-binding method and are eminently suitable for modeling of extended defects in materials with predominantly metallic and covalent type of bonding. Our results confirm that the unusual plastic behavior of bcc transition metals is governed by the properties of the a/2[111] screw dislocations and reveal quantitatively the overall invalidity of the well-known Schmid law in these materials. The most recent improvement of BOP has been a derivation of analytic environmental dependence of bond integrals. This development extends the transferability of the BOP model and its applicability to multi-component systems. The accuracy of this, so-called, screened bond order potential (SBOP) formalism was studied for the first time for the case of pure Mo as well as the intermetallic compound MOSi2. Molybdenum silicides are prospective high-temperature structural materials and full understanding of the deformation behavior of these compounds is a necessary prerequisite for their extensive use in industrial applications
Multiscale approaches to hydrogen-assisted degradation of metals
No full text13661367Hydrogen embrittlement (HE) is a serious and costly industrial problem that affects many commonly used structural metals. Given the wide range of service environments in which hydrogen may occur or be produced, this represents a very serious threat to the structural integrity of machinery and infrastructure in many industries. Despite having been studied for several decades, there is still little consensus regarding the underlying mechanisms for HE. Recently developed theoretical and experimental methods, which enable the evaluation of the influences of hydrogen on the mechanical behavior of metals at the nano-scale, are helping to elucidate new aspects of these mechanisms. However, an urgent need remains to develop tools for the prediction of the reliability and lifetime of materials and components affected by hydrogen. Critical to achieving this goal is the development of accurate descriptions of hydrogen–microstructure interactions under conditions relevant to those occurring in service. As these interactions occur at all length scales, this poses a true multiscale challenge (Fig. 1).66
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
Interactions between lattice dislocations and twin boundaries in tungsten: A comparative atomistic simulation study
No full text31793194Plastic deformation of polycrystalline materials is largely controlled by the interaction between lattice dislocations and grain boundaries. The atomistic details of these interactions are, however, difficult to discern even by advanced high-resolution electron microscopy methods. In this paper, we study several interactions of screw and edge dislocations with two symmetric tilt grain boundaries in the body-centred cubic metal tungsten by atomistic simulations. Two distinct models of interatomic interactions are applied: an empirical Finnis-Sinclair potential and a bond-order potential, which is based on quantum mechanical principles within the tight-binding electronic-structure theory. Our study shows that the outcome of the interactions is sensitive to the employed interatomic potential. The origins of the deviating behaviour can be traced to differences in the description of atomic bonding by the two potentials. Independent of the employed interatomic potential, the simulations reveal that simple empirical criteria for dislocation transmission, which are based on geometry and stress arguments only, do not apply in general. Instead, in most cases, processes occurring at the atomic level play a decisive role in the determination of the underlying mechanisms of dislocations/grain-boundary interactions.8934-3
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