1,720,999 research outputs found
A Variational Derivation of Stoney-Like Formulas for Self-Stressed Bilayered Plates
No full textSince the beginning of the 20th century, it is known that the spontaneous bending of heterogeneous bilayered plates correlates with the self-stress due to the contrast in the material properties of the two layers, and that this correlation can be exploited to gauge the internal stress state. Over the last decades, ever-growing device miniaturization has made stress assessment and even stress engineering an area of major technological interest. In this paper, we obtain two effective 2D models accounting for the spontaneous bending of devices comprised of a thin substrate and a much thinner coating by applying a G -convergence technique to the standard 3D linear hyperelastic model of a bilayered plate. Our procedure is characterized by the introduction of two distinct smallness parameters plus three independent energy scaling parameters
Passive and Active Deformation Processes of 3D Fibre-Reinforced Caricatures of Cardiovascular Tissues
No full textIn this paper, we present a mathematical
model of contractile elastic solids
meant to simulate various districts of the cardiovascular
system, and based on the concepts
of active deformation and embedded muscle -
bres.
Specically, here we deal with the modelling
of the gross mechanics of the left ventricle
(LV) which is strictly related to its pump
function. The muscle bres embedded in the
LV walls govern, through their contraction and
relaxation, the characteristic phases of the cardiac
cycle. Moreover, muscle bres dene the
anisotropy directions of the LV wall, and the
collagene bres determine the material properties
along these directions; thus, to model the
mechanical behaviour of the LV, both the passive
and the active material properties of the
must be accurately accounted for. As is well
known, the eectiveness of the pumping action
is well represented by the pressure-volume
(PV) diagrams that relate the blood pressure
to the volume of the LV during the cardiac cycle.
Here, we aim at reproducing realistic PV
by specifying appropriate sequence of muscle
contractio
Algebraic filtering of surfaces from 3d medical images with julia
No full textIn this paper we introduce a novel algebraic filter, based on algebraic topology methods, to extract and smooth the boundary surface of any subset of voxels arising from the segmentation of a 3D medical image. The input of the Linear Algebraic Representation (lar) Surface extraction filter (lar-surf) is defined as a chain, i.e., an element of a linear space of chains here subsets of voxels represented in coordinates as a sparse binary vector. The output is produced by a linear mapping between spaces of 3-and 2-chains, given by the boundary operator ∂3: C3 → C2. The only data structures used in this approach are sparse arrays with one or two indices, i.e., sparse vectors and sparse matrices. This work is based on lar algebraic methods and is implemented in Julia language, natively supporting parallel computing on hybrid hardware architectures
A NEMD approach to the melt-front evolution under gravity
No full text: Modeling the evolution of the melt front under gravity in the presence of a horizontal thermal gradient is a challenging issue, hitherto tackled exclusively with the concepts and tools of computational continuum thermomechanics, too phenomenologically driven to have satisfactory predictive capabilities. Here, we show that this complex phenomenon is amenable to treatment by the methods and tools of Non-Equilibrium Molecular Dynamics (NEMD). To do so, we addressed all the difficulties caused by the necessity of applying suitable boundary conditions and minimizing surface effects so that the bulk behavior of the system in non-equilibrium conditions can be detected. Sufficient adiabatic separation of the time scales permits us to use macroscopically relatively short-but microscopically long enough-time averages to get the macroscopic bulk behavior of the system accurately. To get an adequate signal-to-noise ratio, we had to use an unphysically large value of the gravity. However, we know from NEMD simulations in transport studies that the phenomena produced are stable over many orders of magnitude. In conclusion, our work proves that molecular simulation can be a good tool to study this family of non-equilibrium phenomena, although further work is needed to achieve quantitative predictive capabilities
Laser Processing in the Manufacture of Dye-Sensitized and Perovskite Solar Cell Technologies
No full textDye-sensitized and perovskite solar cells have seen tremendous efforts in their development in recent years. Amongst these developments are the design and implementation of fabrication techniques that can guarantee high performance as well as scalability over large areas. Laser processing has become a versatile and important tool in many industries and has also been applied successfully to both types of solar cell technologies, culminating in the demonstration of dye solar devices where all temperature treatments have been replaced with laser techniques, and of high-performance solid-state perovskite modules. Herein, we introduce concepts and review the available literature, pertaining to the effective utilization of laser beams for the development of both dye-sensitized and perovskite photovoltaic technologies
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
Exciton-electron scattering in semiconductor microcavities: tool for polariton scattering
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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