1,720,986 research outputs found
High velocity oxy-fuel coating technique: evaluation of residual stresses
No full textThe high velocity oxy-fuel thermal spray coating technique is investigated with regard to the residual stresses which can grow in the coating and in the coated material. The hole-drilling strain-gauge method is used to measure the stresses. Different preheating temperatures of the specimen surface and the influence of the thickness coating are tested. Statistical analyses exclude the influence of the interaction of these variables. While the preheating temperature has a dramatic effect on the measured strain, the effect of the variation of the thickness of the coating is secondary. The residual stress evaluated at the set of most favourable conditions show that the tensile residual stress are of the same magnitude of the yield stress of the material. There is no evidence of coating-substrate interface singularity
Residual stresses in structures coated by a high velocity oxy-fuel technique
No full textThe high-velocity oxy-fuel thermal spray-coating technique is investigated with regard to the residual stresses that can develop in the coating and in the coated material. The hole-drilling strain-gauge method is used to measure the stresses. Different pre-heating temperatures of the specimen surface and the influence of the coating thickness are explored
An ANN and Taguchi algorithms integrated approach to the optimization of CO2 laser welding
No full textNowadays several numerical methods are widely used for either modelling or optimizing the performance of the manufacturing technologies. That has been advanced due to the large diffusion of the personal computer and the numerical algorithms.
The knowledge of those methods and the ability in integrating their functions can make both the manufacturing engineer and the researcher ace their duties.
In this paper, two of those methods have been employed, the backpropagation artificial neural network and the Taguchi approach to the design of the experiment. They were applied to find out the optimum levels of the welding speed, the laser power and the focal position for CO2 keyhole laser welding of medium carbon steel butt weld. The optimal solution is valid in the ranges of the welding parameters that were used for training the neural networks. Extrapolation over those limits would restrict the applicability of the found solution.
The proposed approach would be extendable to other keyhole laser welding processes for different materials and joint geometries. (C) 2006 Elsevier Ltd. All rights reserved
Metal matrix composite products by vibration casting method
Full text linkMetal matrix composites are engineered materials which are a combination of two or more materials, one of which is a metal, whose tailored properties can be attained by systematic combination of different constituents. In this study, titanium carbide particulate reinforced aluminiums 11,8 wt% silicon alloy matrix composites were fabricated by carbon dioxide sand moulding process by varying the particulate addition by weight fraction on percentage basis using mechanical vibration mould. The influence of a wide range of vibration amplitudes and frequencies on the solidification kinetics, microstructure formation and mechanical properties of Titanium carbide reinforced aluminiums 11,8 wt% silicon alloy were examined. Results show strong influence of mould vibration during solidification on the fabricated composites. The mechanical properties such as tensile strength, impact strength, surface hardness and physical properties such as density, thermal conductivity were significantly increased as a result of mould vibration. The maximum tensile strength is 141.125 MPa with vibration and 135.832 MPa without vibration. The maximum impact energy is 15.073 kJ with vibration and 14.514 kJ without vibration and hardness value based Rockwell superficial 15N-S scale is 85.88 for 2% without vibration and 86.08 with vibration. In addition, the change in microstructure and mechanical properties were successfully represented by the changes in solidification characteristics. Various vibration frequencies has reduced the lamellar spacing that changes the microstructure of the composites which as a result became more fibrous. The corresponding changes in mechanical properties indicate that ductility is more influenced by vibration than without vibration. The increase in ductility was believed to be due to the structural refinement
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
Material application, performance and life cycle
Full text linkThis featured article gives a brief outline of what to expect in this section titled “Materials Application, Performance and Life Cycle” of the Reference Module in Material science and Materials Engineering. The scope of the section is very wide due to the wider application areas and types of materials that are available to us. The articles which will be presented will therefore include application of structural materials like, steel, aluminum alloys, concrete, timber, glass, ceramics, composites etc. relevant to all form of buildings, aircrafts, domestic dwellings, machine components, domestic appliances, novelty goods, toys and so on. The section will also include articles which deal with important aspect of materials, namely, performance in service, property evaluation, design for critical functionality, service life evaluation, remnant life and failure prediction. Some articles will delve into the aspect of safety and environmental effect in connection with disposal and recycling of these materials
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
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