1,721,195 research outputs found
Study of the Behavior of Offshore Wind Turbine Monopiles under Monotonic and Cyclic Lateral Loading
No full textpeer reviewedThis chapter presents a study on the behavior of monopiles for offshore wind turbines
under lateral loading, with a special focus on monopiles grounded in clayey soils.
The behavior of the monopile is studied in terms of soil reaction curve. The analysis
focuses on three main points: under monotonic loading, we have analyzed the effect
of the loading velocity on the response of the foundation. Simulations have clearly
shown the influence of loading velocity on the behavior at the soil-pile interface. Then,
based on an anisotropic constitutive law, the influence of both types of anisotropy
(initial and induced by loading) has been studied. Finally, we have considered a nonalternating
cyclic loading, in order to analyze the effect of cyclical accumulation on
force-displacement curves of monopiles
Belgique
Full text linkNowadays, offshore wind energy industry is developing exponentially, due to the significant contribution of the North Sea wind turbines energy production to the total consumed energy in Europe. Given that the EU's energy target is to increase the share of renewable energy by 2020, there is a great potential of the offshore wind energy applications towards this direction. In order to achieve this, the support of scientific research is crucial.
Monopiles have been by far the most common support structure for offshore wind turbine, nowadays becoming applicable also for complex site conditions. Monopiles foundations consist of hollow, thin-walled piles, and they are generally subjected to lateral loading of monoonic and cyclic nature.
The standard design methods are not always suitable for the optimized design of this type of foundation. Especially design of the large monopile under cyclic loading is still demanding the support of scientific research. Therefore, the main objective of this research work is to study the soil-pile interaction problem of offshore wind monopiles under both monotonic and cyclic lateral loading.
The work focuses particularly on monopiles embedded in clayey soils. Special attention is given to the behaviour of natural clays, by proposing a novel constitutive law for natural clay under monotonic and cyclic loading. Furthermore, the constitutive law is employed for numerical analyses of the laterally loaded monopiles problem.FRS-FNRS FRI
Modélisation numérique de la localisation de l'écoulement et des déformations dans les milieux poreux partiellement saturés
No full textGoing 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
Stratégies de Modélisation de Structures en Béton Soumises à des Chargements Sévères
No full textThree modelling strategies for structures are proposed in this document. The first deals with the use of multifiber Timoshenko beam elements and constitutive laws based on damage mechanics for concrete and plasticity for steel. After a short review of different multifiber beam elements existing in the literature, a new Timoshenko element with higher order interpolation functions is proposed. The second strategy concerns Soil-Structure Interaction (SSI) and a 3D non linear interface element, based on the macro-element concept, able to compute SSI for a shallow rigid foundation. The particularity of the macro-element lies in the fact that the movement of the foundation is entirely described by a system of generalised variables (forces and displacements) and the plasticity theory, helping thus to reduce computational time. The third strategy is about localisation of deformations and objectivity of the numerical results using a higher order medium (with microstructure). The evolution of the width of the shear zone is studied using local second gradient models and simple constitutive relations based on plasticity or damage. Comparisons with experimental results and/or numerical examples show the performance of the proposed modelling strategies.Trois stratégies de modélisation de structures sont proposées dans ce document. La première consiste à l'utilisation des éléments poutres multifibres de cinématique Timoshenko et des lois de comportement basées sur la mécanique de l'endommagement pour le béton et la plasticité pour les aciers. Après une présentation succincte de plusieurs éléments poutres multifibres existants dans la littérature, un nouvel élément Timoshenko avec des fonctions d'interpolation d'ordre supérieure est proposé. La deuxième stratégie concerne la prise en compte de l'Interaction du Sol avec la Structure (ISS) et le développement d'un élément d'interface 3D modélisant une fondation rigide superficielle reposant sur un massif de sol. Basé sur le concept des macro-éléments, ce nouvel outil est formulé en variables globales (forces et déplacements) et selon la théorie de plasticité, permettant ainsi de diminuer le temps de calcul. Enfin, la troisième stratégie traite de problème de la localisation des déformations et de l'objectivité des résultats des calculs dans un milieu enrichi (milieu avec microstructure). L'évolution de la zone de localisation est étudiée avec des modèles second gradient locaux pour différents types de lois simples basées sur la théorie de plasticité ou de l'endommagement. Des comparaisons avec des résultats expérimentaux et/ou des exemples numériques prouvent la performance des stratégies de modélisation proposées
Une nouvelle stratégie de modélisation des voiles faiblement élancés soumis à une sollicitation dynamique
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
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