1,720,963 research outputs found
Track-Rex: a universal toolbox for tracking recrystallization nucleation and grain growth behaviors in polycrystalline materials
No full textIn-situ Ti-6Al-4V/TiC composites synthesized by reactive spark plasma sintering: processing, microstructure, and dry sliding wear behaviour
No full textTitanium carbide (TiC) reinforced Titanium Matrix Composites (TMCs) have been synthesized via an in-situ reactive spark plasma sintering (SPS) process using commercial Ti-6Al-4V spherical powders pre-coated with 1 wt% carbon nanoparticles by low-energy ball milling. Graphite flakes are used as carbon source, which aids powder flow during mixing as lubricant. Graphite transforms to nano-crystallite carbon during mixing which is favourable for the rapid formation of TiC second phase in the following SPS process. The composites exhibited a novel honeycomb-like cellular microstructure with the formation of 5–6 vol% fine TiC submicron grains interconnected in the titanium α/β matrix. In addition, the reinforcement of the TiC phase with a nano-hardness of 12.4 GPa, improves the wear resistance of the parent alloy matrix (5.1 GPa), with a reduction of 26–28% in wear rate during dry reciprocating sliding tests against Si3N4 balls. During sliding, the wear debris (predominantly anatase TiO2) builds up on the raised TiC hard phase forming a barrier layer of adhered oxide that can protect the alloy matrix underneath from abrasion and oxidation, leading to a reduced wear rate
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
A study of internal oxidation in carburising steels
No full textThe phenomena known as `internal oxidation' can play a major detrimental role in the failure of
carburised components such as bearings and gears. Internal oxidation leads to a degradation of
the surface layer often leading to surface break up and fatigue. This work is concerned with a
detailed understanding of the formation of internal oxidation leading to modifications to
composition or process parameters to eliminate or reduce internal oxidation.
Experimental steels for the most part have been used in this study with Si content varying from
0.11 to 0.77 mass percent. A commercial carburising process at David Brown Heatch Ltd.
consisting of a number of process stages with varying C potential and treatment temperature has
been used in the study.
Scanning Electron Microscopy (SEM)
,
Cross sectional Transmission Electron Microscopy
(TEM), Energy Dispereive Spectroscopy (EDS) and Electron Probe Microanalysis (EPMA),
Glow Discharge Optical Emission Spectroscopy (GDOES), Quantitative Image Analysis
techniques were applied to characterise the specimens.
A model has been proposed that explains the formation of the characteristic morphology
observed in internal oxidation and is based upon competitive processes concerning the diffusion
rate of alloy species within the bulk material and the differences in the free energy of formation
of the various oxides types. The observed morphology of the internal oxidation zone at different
carburised exposure time, in range of 0.25-16.6h, related to the penetration depth and density of
the internal oxides in the internal oxidation zone, with particular emphasis on the relative
importance of oxygen partial pressure at reaction and free energy of formation of oxides have
been studied. The research indicated that the internal oxides grew fast in the base process. Three
elements Cr, Mn and Si were oxidised at this stage and formed complex oxides within the grains
and on the grain boundaries. Further, as carburising time increased, existing oxides grew and
new oxides nucleated again along grain boundaries. In the boost process, only Si was oxidised.
Si oxides penetrated to a greater depth along the grain boundaries. The generally two-zone
morphology characteristic was found in the internal oxidation zone of carburised steel. Outer
zone: larger size complex oxides which contain higher concentrations of Cr, Mn and some Si on
the grain boundaries or within the grain; Inner zone: intergranular Si oxides on the grain
boundaries. Small dispersed oxide paticles were observed in both zones.
Different oxides were formed in the internal oxidation zone as complex oxides, sometime as
agglomerated oxide phases, and intergranular oxides. These complex oxides were identified as
Cr1.5Mnj.5 O4C, rMnO4, Mn2SiO4 and MnSiO3. The intergranular oxidation was mainly Si oxides,
such as Si02. The agglomerated oxide phases were observed usually as the Cr-Mn complex
oxides with Si oxides or Mn-Si complex oxides growing around them.
The role of Si is critical in that its solid state diffusion coefficient in Fe is considerably higher
than that for Mn and Cr whilst the free energy of formation of Si oxide is lower than that for Mn
and Cr. It affects internal oxidation, not only on the morphology but also the rate of penetration.
For the specimen with low Si bulk content, the internal oxidation zone consisted of larger
complex oxides elongation close to the surface, with intergranular oxidation remote from
surface. The penetration depth of the internal oxides increased with increasing bulk Si content.
In this case, oxygen diffused not only through the metal lattice but also at an enhance rate along
the internal oxides/metal matrix interface. There was a peak value, after which as Si increased in
the bulk metal, more intergranular oxidation was formed instead of the larger oxides. A
continuous layer was formed parallel to the surface that reduced further diffusion of oxygen.
The penetration depth of the internal oxides decreased with further increases of bulk Si content.
The higher the carbon potential, the lower was the penetration depth of the internal oxides and
the less dense the internal oxidation zone.</p
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
- …
