1,720,964 research outputs found
THE STUDY ON INTERFACIAL BONDING OF EXPANDABLE GRAPHITE BASED INTUMESCENT COATING USING BENTONITE CLAY
Get PDFThe fast development of science and technology provides us withsophisticated products but concurrently increases the use of combustible materials.The usage of polymeric materials in everyday life increases the risk of fire hazards;therefore flame retardants are often incorporated into them to limit their flammability.This study characterized the interfacial bonding of expandable graphite based intumescent coating on steel substrate with respect to its physical, chemical and mechanical properties after fire test. A range of expandable graphite based
intumescent coating formulations were developed with various additives. In these formulations, bentonite clay filler was incorporated to improve the adhesion of coating with substrate. Structural steel substrate was sand blasted and coated with primer coating of zinc phosphate.
For mechanical properties, the shear test was conducted according to ASTM 3 163 test procedure and the maximum shear strength was 9.89Mpa for an intumescent coating formulation containing 6% of bentonite clay and 1.32Mpa for formulation without bentonite clay. X-Ray Diffraction 0r)esults s howed boron phosphate,graphite and sassolite were remaining inorganic materials that acted as a thermal
barrier or protecting layer at later stages of burning. Formulation containing 6% of bentonite clay had the highest residual weight which was 33.45% and formed a ceramic like protective shield at the char surface thus indicated it has good intumescent effect compared to 25.33% for coating without bentonite clay at 800'c
The effects of annealing on microstructural changes for aluminium nitride epitaxial grown on sapphire by transmission electron microscopy
Get PDFThe performance of semiconductor devices depends strongly upon the microstructure of the materials. Therefore the microstructural control is intrinsically important for fabrication of high performance devices. In this research, the microstructures have been analysed in detail and the mechanisms of microstructural changes in aluminium nitride (AlN) epitaxial have been clarified for the establishment of the growth method. AlN heteroepitaxial layers were made by growing an AlN buffer layer on a (0001) sapphire substrate by the Metal Organic Vapor Phase Epitaxy (MOVPE) growth process. Annealing treatments were added before and after the deposition of an AlN buffer layer. The surface roughness of AlN was observed with an Atomic Force Microscope (AFM) and X-ray Rocking Curve (XRC). The cross section of AlN heteroepitaxial was observed by using Transmission Electron Microscope (TEM) at 200 Kv and High-Angle Annular Dark- Field (HAADF) images were observed with a Scanning Transmission Electron Microscope (STEM) at 300 kV. Thin foil specimens or lamella for the TEM observation were made using a Focused Ion Beam (FIB) mill with accelerating voltage of 15 kV~3 kV for a smooth finishing of lamella. Prior to the deposition of a medium temperature MT-AlN layer, the sapphire substrate was cleaned or preannealed at a high temperature, TAn under the atmosphere of H2. For annealing temperature, TAn less than 1250°C , the crystallinity improved but twisting domains appeared above the temperature. Threading dislocations (TDs) of type c and typea+ c with 108 cm-2 dislocation density was observed. However when the temperature was increased to 1350°C, threading dislocation were reduced. On the other hand, post deposition annealing at a high temperature between 1500ºC and 1700oC for 2 hours under the atmosphere of N2+CO was carried out. Cross sectional TEM revealed that after annealing at 1500oC, cone-shaped domains and threading dislocations remained. The morphology of domains and the changes in TEM image contrast strongly suggest that the domains are inversion domains. TDs of type-a and type- a+c were visible for g =01-10 under the two beam condition. However, after annealing at 1550oC, the cone shaped domains coalesced with each other to leave a single domain boundary running in a zigzag laterally at the center of AlN buffer layer that the upper layer has the Al- polarity while the lower layer has the N-polarity determined by the HAADF analysis. The inversion domain boundary become smooth and flatter with the rising annealing temperature. The surface of MT-AlN buffer was finely rugged before the annealing, but became coarser and smoother with annealing. The changes in the surface morphology indicates the occurrence of grain coalescence. The density of TDs was reduced to roughly 5×108 cm-2 after annealing at 1650oC. Conclusively, this research confirms that pre-deposition and post deposition annealing are an effective treatment to control the microstructure and to reduce the dislocation density for advancement of semiconductor devices
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
Electron microscopy determination of crystallographic polarity of aluminum nitride thin films
Get PDFVariations 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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