1,720,967 research outputs found
Development of a preliminary sizing tool forstrategic decision making in composite fuselages using weight and cost optimization
No full textThis study is an attempt to develop a preliminary composite fuselage sizing tool for the decision making process utilizing analytical structural analysis equations and a bottom-up cost approach to estimate weight and cost. Previous research by several authors and companies is reviewed in order to define the knowledge gaps that the project is going to fill. The objectives of this project are divided into two directions. The first one is the weight and cost fuselage design, and the second, is the weight and cost optimization process. After examining the existing literature both from academia and industry a different approach is proposed for each sector. In the structural design an analytical based model is proposed to assess the components integrity while cost equations for fully learned manufacturing processes are used based on the Advanced Composites Cost Estimation Manual (ACCEM). An experience-driven optimization algorithm is proposed afterwards, taking into account manufacturing considerations and design rules of thumb. By combining these tools, a general tool for fuselage design that is completely suited for the preliminary design phase is proposed. Τhe trade-off studies can provide important knowledge on the effect of different decisions and establish new design guidelines. The study concludes that an increase of the number of stiffeners and frames, in a fuselage structure, leads to a general decrease in weight and an increase in manufacturing cost. The addition of more stringers or frames after a certain level leads to an increase in weight, while the cost follows the same trend. The manufacturing constraints and the design rules-of-thumb applied lead to an increase in structural weight. Finally, the comparison between skin-stiffened and sandwich designs, shows that the weight saving potential is comparable for both configurations, and the cost saving potential is higher for the sandwich design.Aerospace Engineerin
The cost-effectiveness of Studies Within A Trial (SWATs) for improving recruitment and retention in randomised trials
Get PDFBackground: Randomised controlled trials (RCTs) constitute the gold-standard design for evaluating interventions. However, their design, conduct and validity can be threatened by slow recruitment of invited patients and/or attrition of already recruited participants. Given such challenges, the research community is increasingly interested in identifying effective recruitment and retention strategies via the conduct of Studies Within A Trial (SWATs). Aims: This thesis applies economic techniques to demonstrate the significance of trial recruitment and retention, and to introduce economic methods for improving the evaluation of recruitment and retention strategies via SWATs.
Methods: The thesis employs a wide range of health economic methods, including decision modelling, costing analysis, systematic review and Value of Information (VoI) analysis. Results: Chapter 2 presents the impact of slow recruitment to the RECOVERY trial generated opportunity costs due to the delayed dissemination of a more cost-effective, available treatment for hospitalised COVID-19 patients. Chapter 3 highlights that participant loss to follow-up from the Occupational Therapist Intervention Study (OTIS) trial generated significant financial costs to the trial team and funder, despite its low attrition rate. Chapter 4 critically appraises the evidence surrounding the cost-effectiveness of recruitment and retention strategies, concluding that no cost-effective strategy exists with high certainty of evidence, due to the limited availability of economic evaluations alongside most SWATs. Finally, considering the limited resources for funding future SWATs, Chapter 5 introduces and applies a Value of Information (VoI) analysis framework to telephone reminders (recruitment strategy) and pens (retention strategy), showing that such a methodology can be feasibly used as a tool, alongside Trial Forge Guidance 2, for prioritising research on recruitment and retention strategies. Conclusion: Integrating economic evaluations into SWATs and using VoI analyses can strengthen future SWAT-related research, allowing trial methodologists to improve the conduct of their studies
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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