1,721,604 research outputs found
Introduction
No full textThe geographical focus of this book pertains to Europe and Central Asia, while thematically, the seven chapters concentrate on a group of diseases, collec tively termed neglected tropical diseases (NTDs). Geographically, Europe and Central Asia are a contiguous area. Yet, this vast territory is characterized by considerable heterogeneity and enormous cultural, ecological, economic, political, and social diversity, which, in turn, govern people's health and well-being. For the purpose of this book, Europe and Central Asia are defined as the continent of Europe plus the Asian part of the former Soviet Union, namely Siberia, the Caucasus region, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. Essentially, this overlaps with the World Health Organization (WHO) European Region (EURO). The bio-eco-geographical diversity of this region is reflected in widely varying biomes, including arctic tundra, extensive forests, steppes, deserts, mountains, and Mediterranean areas. Of note, this region does not include tropical areas in a strict geographical or climatological sense
A formulation for an unsaturated porous medium undergoing large inelastic strains
Full text linkThis paper presents a formulation for a saturated and partially saturated porous medium undergoing large elastic or elastoplastic strains. The porous material is treated as a multiphase continuum with the pores of the solid skeleton filled by water and air, this last one at constant pressure. This pressure may either be the atmospheric pressure or the cavitation pressure. The governing equations at macroscopic level are derived in a spatial and a material setting. Solid grains and water are assumed to be incompressible at the microscopic level. The isotropic elastoplastic behaviour of the solid skeleton is described by the multiplicative decomposition of the deformation gradient into an elastic and a plastic part. The effective stress state is limited by the Drucker-Prager yield surface, for which a particular "apex formulation" is advocated. The water is assumed to obey Darcy's law. Numerical examples of strain localisation of dense and loose sand conclude the paper
A model for unsaturated porous media undergoing large inelastic strains
No full textA formulation for a partially saturated porous medium undergoing large elastoplastic deformations is presented. The porous medium is treated as a multiphase continuum with the pores of the solid skeleton filled by water and air, this last one at constant pressure, which is taken as reference pressure (passive air phase assumption). This pressure may either be the atmospheric pressure or the cavitation pressure (isothermal monospecies approach). The governing equations at macroscopic level are derived in a spatial and a material setting. Solid grains and water are assumed to be incompressible. The elasto-plastic behaviour of the solid skeleton is described by the multiplicative decomposition of the deformation gradient into an elastic and a plastic part. The Kirchhoff effective stress tensor and logarithmic principal strains are used in conjunction with an hyperelastic free energy function. The effective stress state is limited by the Drucker-Prager yield surface. The water is assumed to obey Darcy's law. Numerical examples of the Liakopoulos test and of strain localisation of undrained dense sands under quasi static loading conditions conclude the paper
A model for a partially saturated geomaterial undergoing large inelastic strains
No full textA formulation for a partially saturated porous medium undergoing large elastic or elastoplastic deformations is presented. The porous medium is treated as a multiphase continuum with the pores of the solid skeleton filled by water and air, this last one at constant pressure, which is taken as reference pressure (passive air phase assumption). This pressure may either be the atmospheric pressure or the cavitation pressure (isothermal monospecies approach). The governing equations at macroscopic level are derived in a spatial and a material setting. Solid grains and water are assumed to be incompressible at microscopic level. The elasto-plastic behaviour of the solid skeleton is described by the multiplicative decomposition of the deformation gradient into an elastic and a plastic part. The Kirchhoff effective stress tensor and logarithmic principal strains are used in conjunction with an hyperelastic free energy function. The effective stress state is limited by the Drucker-Prager yield surface. The water is assumed to obey Darcy's law. Numerical examples of the Liakopoulos test and of strain localisation of undrained dense sands under quasi static loading conditions conclude the present contribution
On the computation of configurational forces in anisotropic hyperelastic solids
No full textIn the field of configurational mechanics we study energetic changes associated to variations of material configurations. The central part in this notion is the energy momentum tensor, also known as the Eshelby stress tensor, which enters the configurational force balance. The mechanics of material forces has been successfully applied to a variety of important fields in applied mechanics such as e.g. the evolution of interfaces, growth in biomechanical systems, the kinetics of dislocations, fracture mechanics, morphology/structure optimization in heterogeneous microstructures.
In most contributions configurational forces are computed for isotropic bodies; in this presentation we consider the influence of anisotropy. As a specific model problem we consider a single-edged-tension specimen, where we analyze the sensitivity of the configurational forces in amplitude and orientation with respect to changing main axes of anisotropy of a hyperelastic material. These configurational forces can be interpreted as driving forces on the crack tips of the considered boundary value problem, which are directly related to the classical J -integral in fracture mechanics. In order to guarantee the existence of minimizers we use an anisotropic polyconvex energy. Here, we focus on a transversely isotropic constitutive law formulated in the framework of invariant theory
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
Finite strain localisation in water saturated porous media
No full textReport no.12/1997, Institut für Baumechanik und Numerische Mechanik, Universität Hannover, (Germany), 1-3
Variations 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
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