1,720,976 research outputs found
Methodologies for virtual sensing applied to aeronautical and ship structures
Full text linkIn this thesis the problem of achieving a full, experimentally based, representation of the load and elastic deflection response of aeronautical and ship structures is concerned by the development of numerical procedures and their assessment via related experimental activities. The objective is to provide reliable estimations of elastic deflections and external forces throughout the structure using noisy pointwise measurements. This issue is critical for some important structural engineering applications such as Structural Health Monitoring and Condition-Based Maintenance.
The most important tools generally used for this purpose (e.g., Kalman filter) have been first reviewed, pointing strengths and critical issues out. Then, an approach based on an optimal second-order natural observer has been proposed also integrating this with signal processing approaches like discrete wavelet transform and finite-element component analysis approaches like dynamics condensation. The developed and integrated numerical framework was finally applied to the state estimation of two specific structures, namely, an aircraft and surface vessel operating under unsteady environmental conditions featured by wind gust or sea waves, respectively.
More in detail, a scaled physical model of a fast catamaran, tested in the towing-tank, and a numerical model of a flexible aircraft were studied as significant test cases for assessing the introduced methodologies. Both the structures involved are interesting in their respective research fields.
The accurate and complete estimation of the structural dynamics behavior of the fast catamaran is particularly interesting since in real world it might be exposed to critical slamming phenomena on the wetdeck region. The experimental set-up and in particular the choice of the structural measurements were crucial to have a minimum but reliable database for the reconstruction of the structural deflection field. By applying the above methodologies, it was also possible to provide a deeper insight relative to violent fluid-structure interaction phenomena and to evaluate possible fatigue-life reduction for components where direct monitoring was not possible.
The other case study consists of an aircraft research model that experiences a particular kind of instability involving both aeroelasticity and flight dynamics. In such aeronautical application, the structural measurements are virtually obtained by means of simulations based on a flight dynamics and aeroelasticity toolbox developed for the present purpose and featured by an accurate description of the coupling caused by aerodynamic and inertial forces. This case has been performed to investigate numerically the technique proposed in this thesis by integrating the methodology with multi-resolution analysis
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
Experimental investigation vs numerical simulation of the dynamic response of a moored floating structure to waves
Full text linkA combined experimental/numerical investigation of a moored floating structure response to incoming waves is presented. The floating structure consists of three bodies, equipped with fenders, joined by elastic cables. The system is also moored to the seabed with eight mooring lines. This corresponds to an actual configuration of a floating structure used for ships and submarines in special docking operations. The dynamic wave response is investigated by performing experiments in a towing tank equipped with a wave maker. Experimental results are compared with numerical simulations in regular and irregular waves, showing a good agreement. The predicted time histories of pitch, heave and surge motions of the three-body structure and of the mooring line forces bear very satisfactorily the experimental results in regular head waves. The case of irregular waves is also encouraging, since the statistics of the response is correctly kept up to the fourth-order statistical moments. This confirms that the theoretical model proposed in this paper is a suitable tool to predict the actual behaviour of a complex moored structure at sea
A new approach to stochastic flow induced vibration in two-dimenisonal elastic structures
No full textVariations 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
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
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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