1,721,092 research outputs found
Tailoring the in-situ formation of intermetallic phases in the self-lubricating Al-WS2 composite for enhanced tribological performance with wear track evolution analysis
No full textSelf-lubricating aluminium matrix composites with enhanced tribological properties are sought for weight critical applications. In previous studies, the Al composites incorporating the solid lubricant WS2 have been shown to reduce both the coefficient of friction and wear rate, positioning them as promising candidates in various tribological applications (e.g. automotive industry). However, the impact of interfacial reactions between Al and WS2 during composite production on tribological performance has still not yet been explored. This study highlights the hardening effect of the reaction products. Despite some literature assuming a negative impact of these reactions as they consume WS2 in the composites, this study presents evidence that this cannot be generalised for the overall outcome. Interestingly, a controlled amount is shown to be beneficial for tribological properties. In this work, the tribological influence of the Al-W intermetallic structure forming during spark plasma sintering of the Al-WS2 composites was investigated. The microstructure was tailored by adjusting the manufacturing temperature between 500 and 600 °C. The Al-WS2 fabricated at 580 °C exhibited the lowest coefficient of friction and specific wear rate (reduced by 20% and 97%, respectively, compared to the one fabricated at 500 °C. Furthermore, the worn surface morphology in different stages during friction was evaluated by a novel wear track evolution analysis. This study confirmed that offering a balance between the fraction of solid lubricants and in-situ formed hard intermetallic structure is crucial to the effective formation a protective layer on the worn surface
Solar UAV : structural dynamic analysis of critical components
No full textThis thesis provides a detailed outline of the author’s final year project in Nanyang Technological University, School of Mechanical and Aerospace Engineering. This project consists of constructing a solar powered Unmanned Aerial Vehicle (UAV) with the requirements of Medium Altitude Long Endurance (MALE). The end objective of this project is for the Solar UAV to be able to maintain non-stop flight for 24 hours. With a team of ten final year students, the author seeks to design and construct the UAV, with sub-teams such as aerodynamics, structures, solar, avionics and propulsion. Being part of the structures team, the main role of the author is to conduct structural analysis on all the components of the plane using FEM software. As this is a large scale project that will span over another approximately two years, the author has included an abbreviated manual on how to use a FEM software, ABAQUS, in the FYP report.Bachelor of Engineering (Mechanical Engineering
Redesign, analysis, fabrication and testing of light weight fuselage, boom and empennage for solar UAV : part 1
No full textIn recent years, a lot of research efforts have been put into Unmanned Aerial Vehicle (UAV) due to its ability to perform a wide variety of missions which include surveillance and recon, search and rescue operations, transport operations and other special operations deemed too dangerous or unsuitable for manned aerial vehicle.
The Solar UAV Project is one such research project involving Final Year Aerospace Engineering students from Nanyang Technological University (NTU) and the Defence Science Oganisation (DSO) National Laboratories. This project aims to design and build a High Altitude and Long Endurance (HALE) UAV powered by solar energy.
Entering the 3rd year of the project, the author will continue the work of his predecessors and focus his efforts on the design and structural analysis of the empennage section.
In this report, the author will first detail the design process he has undergone, following an evaluation of the design done in the previous year. After a series of design re-iterations, the author arrived at 2 empennage configurations for the final considerations.
Based on the design criteria set up by the mission requirements, the author will then evaluate his designs to determine which configuration will be used for the Solar UAV. This evaluation will include the weight trade-off analysis for the empennage section and the structural analysis of the critical members in the empennage.
In addition, the author will also detail the experiment process he had undergone with the test spar manufactured in order to obtain important material properties which will be useful for subsequent phases of the project.
Future work for this portion of the project includes finalized engineering drawings required for the production of the empennage section and an in-depth structural analysis and optimization of the components.Bachelor of Engineering (Aerospace Engineering
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
Variations 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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