1,720,955 research outputs found
Design and evaluation of an abrasive saw kickback machine
No full textThesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2020Supervised by Alexander H. Slocum. Cataloged from the PDF version of thesis.Includes bibliographical references (page 65).Injuries from power saw kickback are often fatal. However, only woodcutting saws have regulations and assessment methodologies for kickback. These regulations do not apply to metal and masonry saws, as the cutting mechanism and dominant kick-back mode are different from those of woodcutting saws. In this work, the kickback of abrasive saws is investigated by combining theoretical and experimental tools. A theoretical model developed based on frictional engagement during a pinch-based kickback event is shown to predict the resultant kickback energy for various saws in good agreement with experimental measurements. These measurements were obtained using a specialized machine that was designed to generate pinch-based kickback and to measure the resultant kickback energy for both chainsaws and cutoff saws. While the model can predict the resultant kickback energy for a saw given known cutting conditions (i.e. cutting angle and pinch force), it does not predict the maximum possible kickback energy given any cutting angle of a saw because it does not account for the change in speed of the cutting blade. Upon validation of the physics model, two commonly used representative saws, a Stihl TS420 and an ICS 695XL, were tested using this kickback machine to evaluate their comparative kickback risk. This work demonstrates that pinch-based kickback can be a major safety risk for abrasive saw operators, and it provides a machine and analytical framework for evaluating this risk.by Steven Burcat.S.M.S.M. Massachusetts Institute of Technology, Department of Mechanical Engineerin
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
Design and Manufacture of a Modular Continuous Unit Dose Pharmaceutical Lyophilizer
No full textPharmaceutical lyophilization (freeze-drying) enables long term storage and simplified transportation for aqueous vaccines and protein formulations. Modern industrial pharmaceutical freeze-driers rely on large batch and open loop formulation processing, limiting supply chains and resulting in variable quality products. This work describes the design and manufacture of a modular continuous lyophilization machine for pharmaceutical production. Additionally, the scaling and design methodology outlined in this work enables the development of both smaller systems for laboratory testing and larger machines to fit the needs and requirements of individual facilities. This machine introduces three new technologies to the pharmaceutical freeze-drying process. The first innovation is a continuous flow lyophilization topology which separates the lyophilization steps spatially rather than temporally. This layout allows product to travel through the system in smaller batches for increased product uniformity and quality control. The second innovation is a weight-based sensor for monitoring residual water content. This sensor enables in-situ monitoring of product during sublimation, and it resolves mass measurements as small as 5mg. The third innovation is the implementation of a thermal shock method of inducing controlled nucleation. The convective cooling and spatial non-uniformity within the machine allow vials to experience a 40°C temperature drop in less than 30 seconds. This nucleation front starts on the vial walls, rather than at the top surface of the solution in the vial, potentially increasing the water sublimation rate during drying compared to current nucleation methods. The machine designed and built for this work integrates into modern factory processes and can be scaled from the lab bench to a production line. The manufactured prototype demonstrates improvements on the production rate, flexibility, and quality of existing machines.Ph.D
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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