1,721,147 research outputs found
Topology Optimization of Vibration Bi-material Structures with Respect to Sound Radiation
No full textTopology optimization of structures subjected to dynamic load
No full textDenne rapport omhandler topologioptimering af kontinuerte strukturer uden dæmpning, som bliver udsat for en harmonisk varierende belastning, der er uafhængigt af designet. Belastningens amplitude og excitationsfrekvens er givet på forhånd. Formålet med optimeringen er at maksimere den dynamiske stivhed, som svarer til at minimere den dynamiske compliance. Når sådan et problem løses sker det normalt ved at resonansfrekvenserne skubbes så langt væk som muligt fra den givne excitationsfrekvens. I denne rapport optimeres der ikke direkte på resonansfrekvenserne, idet problemet løses ud fra de tvungne svingninger. Resultatet er dog, at resonansfrekvenserne skubbes væk fra excitationsfrekvensen. Løsningen af problemet er baseret på en enkeltmateriale model og en bi-tykkelsesmodel, som anvender SIMP modellen for at penalisere materialet, og designvariablene er elementernes volumendensitet. Det tilladelige designvolumen, randbetingelserne og materialevolumenet er definerede på forhånd. Det er regnet på flere repræsentative eksempler, og løsningerne vises
Stochastic Finite Elements in Reliability-Based Structural Optimization
Get PDFApplication of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect to optimization variables can be performed. A computer implementation is described and an illustrative example is given.Application of stochastic finite elements in structural optimization is considered. It is shown how stochastic fields modelling e.g. the modulus of elasticity can be discretized in stochastic variables and how a sensitivity analysis of the reliability of a structural system with respect to optimization variables can be performed. A computer implementation is described and an illustrative example is given
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
Three Dimensional Stability and Bifurcation of Steady Water Waves
No full textThe stability of finite amplitude two-dimensional waves of permanent form on deep water to arbitrary three-dimensional disturbances is considered. The possibility of instability is related to the existence of resonances between linear waves. The regions of instability are calculated. It is shown that spontaneous three-dimensional waves of permanent form can arise, from bifurcation of two-dimensional waves at wave heights and wave lengths for which stationary disturbances exist, and their properties are determined
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
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