scholarly journals Double poroelasticity derived from the microstructure

2021 ◽  
Author(s):  
Laura Miller ◽  
Raimondo Penta
Keyword(s):  
Global Scale ◽  
Homogenization Method ◽  
Local Scale ◽  
Scale Model ◽  
The Novel ◽  
Periodic Cell ◽  
The Matrix ◽  
Poroelastic Material ◽  
The Given

AbstractWe derive the balance equations for a double poroelastic material which comprises a matrix with embedded subphases. We assume that the distance between the subphases (the local scale) is much smaller than the size of the domain (the global scale). We assume that at the local scale both the matrix and subphases can be described by Biot’s anisotropic, heterogeneous, compressible poroelasticity (i.e. the porescale is already smoothed out). We then decompose the spatial variations by means of the two-scale homogenization method to upscale the interaction between the poroelastic phases at the local scale. This way, we derive the novel global scale model which is formally of poroelastic-type. The global scale coefficients account for the complexity of the given microstructure and heterogeneities. These effective poroelastic moduli are to be computed by solving appropriate differential periodic cell problems. The model coefficients possess properties that, once proved, allow us to determine that the model is both formally and substantially of poroelastic-type. The properties we prove are a) the existence of a tensor which plays the role of the classical Biot’s tensor of coefficients via a suitable analytical identity and b) the global scale scalar coefficient $$\bar{\mathcal {M}}$$ M ¯ is positive which then qualifies as the global Biot’s modulus for the double poroelastic material.

Hydrodynamic Analysis of Macroalgae Local Model Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Ming Chen ◽  
Solomon C. Yim ◽  
Daniel Cox ◽  
Zhaoqing Yang ◽  
Thomas Mumford
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Current Model ◽  
Global Scale ◽  
Local Scale ◽  
Constant Current ◽  
Scale Model ◽  
Effective Diameter ◽  
Hydrodynamic Coefficients

Abstract In this article, a local scale, fully nonlinear coupled fluid-structural interaction (FSI) sugar kelp model has been developed using a computational fluid dynamics (CFD) method. In this model, to be consistent with available experimental data, the sugar kelp is approximated as elongated rectangles with smoothed isosceles triangles at the ends and a single kelp model with one end fixed in a channel with constant current model is developed. Several different current speeds are simulated, and the resulting drag forces and calculated drag coefficients are validated by comparison with experimental data from the literature. In a previous study, a global scale model was developed using a computational structural dynamics (CSD) method to simulate macroalgae farming system and guide the system configuration design. In the global scale model, the hydrodynamic forces are calculated using Morison’s equation and the kinematics and dynamics of the sugar kelp are simplified and the group of kelps attached to the long line is modeled as a slender structure with the same length and an effective diameter such that the volumes are consistent with the real physical system. This simplified model matches the weight and buoyancy but adjusting the hydrodynamic properties when the general hydrodynamic coefficients are employed. Therefore, optimal hydrodynamic coefficients used in global scale model were determined to obtain the hydrodynamic force more accurately. The validated local scale model is then be applied to determine the hydrodynamic coefficients of the simplified sugar kelp model for global dynamic analysis.

A Multi-Scale Scheme for Modelling Fracture under Dynamic Loading Conditions

2014 ◽  
Vol 627 ◽  
pp. 37-40
Author(s):  
A. Karamnejad ◽  
L.J. Sluys
Keyword(s):  
Dynamic Loading ◽  
Static Problem ◽  
Global Scale ◽  
Local Scale ◽  
Material Point ◽  
Computational Homogenization ◽  
Scale Model ◽  
Multi Scale ◽  
Damaged Zone ◽  
Scale Scheme

Fracture in heterogeneous materials under dynamic loading is modelled using a multi-scale method. Computational homogenization is considered, in which the overall properties at the global-scale are obtained by solving a boundary value problem for a representative volume element (RVE) assigned to each material point of the global-scale model. In order to overcome the problems with upscaling of localized deformations, a non-standard failure zone averaging scheme is used. Discontinuous cohesive macro-cracking is modelled using the XFEM and a gradient-enhanced damage model is used to model diffuse damage at the local-scale. A continuous-discontinuous computational homogenization method is employed to obtain the traction-separation law for macro-cracks using averaged properties calculated over the damaged zone in the RVE. In the multi-scale model, a dynamic analysis is performed for the global-scale model and the local-scale model is solved as a quasi-static problem. Dispersion effects are then captured by accounting for the inertia forces at the local-scale model via a so-called dispersion tensor which depends on the heterogeneity of the RVE. Numerical examples are presented and the multi-scale model results are compared to direct numerical simulation results. Objectivity of the multi-scale scheme with respect to the RVE size is examined.

scholarly journals The Role of Chapter Titles in Revealing the Authorial Intent in the Novel “The Girl Who Saved the King of Sweden” by Jonas Jonasson

2021 ◽  
pp. 55-62
Author(s):  
Н.Ю. Степанова
Keyword(s):  
Linguistic Analysis ◽  
Overwhelming Majority ◽  
Modern Literature ◽  
The Novel ◽  
Binary Opposition ◽  
Authorial Intent ◽  
Popular Novel ◽  
The Given

В статье рассматривается роль названий глав в юмористическом романе Юнаса Юнассона «Девочка, которая спасла короля Швеции» (Jonas Jonasson “The Girl Who Saved The King of Sweden”, 2014) в раскрытии авторского замысла в целом и создании комического эффекта в частности. На сегодняшний день отсутствуют лингвистические исследования данного популярного романа, который представляет прекрасный образец современного юмористического произведения и отражает актуальные тенденции работы с художественным словом, что обусловливает актуальность и научную новизну работы. Автор статьи на материале романа Ю. Юнассона анализирует структурные и смысловые особенности заголовков, опираясь на теорию, разработанную в своем диссертационном исследовании, посвященном контрасту как средству создания комического эффекта, предлагает классификацию названий глав по структурному и семантическому признаку; доказывает, что подавляющее большинство заглавий построены по принципу бинарной оппозиции, проводит подробный лингвостилистический анализ наиболее интересных, основанных на контрасте заглавий, делает выводы об их роли в реализации авторского замысла. The paper discusses the role of the chapter titles of the humorous novel by Jonas Jonasson “The Girl Who Saved the King of Sweden” in revealing the authorial intent, namely the comic effect. The popular novel by Jonas Jonassson is a perfect specimen of modern humorous fiction reflecting up-to-date literary trends, however, it has not undergone any thorough linguistic analysis so far. This fact determines the topicality and novelty of the research conducted. The paper contains an overview of the functions of titles and a thorough analysis of the structural and semantic peculiarities of the chapter titles in the given novel. It also offers their classification due to several aspects. The research is based on the theory of the mechanism of creating the comic effect in humorous fiction developed by the author in her Ph.D. thesis, focusing on contrast as the key means of creating the comic effect in modern literature. Based on the results of the research, the author of the article concludes that the overwhelming majority of the chapter titles under analysis can be structurally defined as binary opposition clusters. To conclude, chapter titles play an integral part in bringing the author’s intent home to the reader.

scholarly journals An Enhanced Stochastic Two-Scale Model for Metal-to-Metal Seals

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 87 ◽  
Author(s):  
Francesc Pérez-Ràfols ◽  
Andreas Almqvist
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Approach ◽  
Global Scale ◽  
Solution Procedure ◽  
Local Scale ◽  
Scale Model ◽  
Length Scales ◽  
Geometrical Features ◽  
Mesh Density ◽  
The Mathematical Model

Leakage in static metal-to-metal seals is predominantly determined by the topography of the contacting surfaces. The topography consists of features that span the entire range from its carefully engineered geometry down to micro-sized surface asperities. The mesh density necessary to fully resolve all the features, in this large span of length scales, generates too many degrees of freedom for a direct numerical approach to be applicable. Some kind of sophistication, either incorporated in the mathematical model or in the numerical solution procedure or even a combination of both is therefore required. For instance, in a two-scale model, the geometrical features can be addressed in the global-scale model, while the features belonging to length scales smaller than a given cut-off value are addressed in the local-scale model. However, the classical two-scale approaches do not explicitly address the stochastic nature of the surfaces, and this has turned out to be a requirement in order to obtain quantitative predictions of leakage in metal-to-metal seals. In this work, we present a continued development of an already existing two-scale model, which incorporates a stochastic element. The novelty lies in the way we characterise the permeability at the local scale and how this is used to build a more efficient and useful approach.

scholarly journals Thromboinflammation in COVID-19: The Clot Thickens

2021 ◽  
Author(s):  
Raayma Iffah ◽  
Felicity Gavins
Keyword(s):  
Immune System ◽  
Cell Activation ◽  
Subsequent Development ◽  
Drug Repurposing ◽  
Global Scale ◽  
The Novel ◽  
Endothelial Cell Activation ◽  
Multiple Systems ◽  
Novel Coronavirus

Since the start of the novel coronavirus SARS-Cov-2 pandemic, a disease that has become one of the world’s greatest global health challenges, the role of the immune system has been at the forefront of scientific studies. The pathophysiology of COVID-19 is complex, which is evident by those at higher risk for poor outcome. Multiple systems contribute to thrombosis and inflammation seen in COVID-19 patients, including neutrophil dysfunction, platelet activation, endothelial cell activation. Understanding how the immune system functions in different patient cohorts (particularly given recent emerging events with the Oxford/AstraZeneca vaccine) is vital to understanding the pathophysiology of this devastating disease and for subsequent development of novel therapeutic targets and expedite possible drug repurposing strategies that could benefit society on a global scale.

LEAST‐SQUARES INVERSE FILTERING

Geophysics ◽  
1966 ◽  
Vol 31 (5) ◽  
pp. 917-926 ◽  
Author(s):  
Wayne T. Ford ◽  
James H. Hearne
Keyword(s):  
Least Squares ◽  
Autocorrelation Function ◽  
Scale Factor ◽  
Inverse Filtering ◽  
Sampled Signal ◽  
The Matrix ◽  
Minimum Delay ◽  
The Given ◽  
Unknown Signal

Suppose we are given the autocorrelation function of a certain unknown sampled signal. Although a number of different signals might produce the given autocorrelation function, only one of these is minimum‐delay. Denoting this minimum‐delay unknown signal by the matrix K, the given autocorrelation may be written in the form K′K where K′ is the transpose of K. It is desired to determine approximately the inverse of this unknown signal K; that is, we wish to determine a vector X so that KX is as close to B′=(1, 0, 0, ⋯, 0) as possible in a least‐squares sense. If K were known, Rice shows that [Formula: see text] At first glance, the above formula appears useless as K′ is unknown. However, although K′ is indeed unknown, K′B has the form K′B=(c, 0, 0, ⋯, 0)′ where the scalar c simply plays the role of a scale factor. Thus, we determine X by simply selecting a convenient multiple of the first column of the inverse of the known matrix K′K. Although we do not present the details of the computer programming involved in the above calculation, we do present some simple examples to illustrate the process.

scholarly journals A stochastic two-scale model for pressure-driven flow between rough surfaces

2016 ◽  
Vol 472 (2190) ◽  
pp. 20160069 ◽  
Author(s):  
Francesc Pérez-Ràfols ◽  
Roland Larsson ◽  
Staffan Lundström ◽  
Peter Wall ◽  
Andreas Almqvist
Keyword(s):  
Flow Pattern ◽  
Present Model ◽  
Global Scale ◽  
Local Scale ◽  
Scale Model ◽  
Small Domain ◽  
Small Flow ◽  
Pressure Driven Flow ◽  
Stochastic Element ◽  
Scale Roughness

Seal surface topography typically consists of global-scale geometric features as well as local-scale roughness details and homogenization-based approaches are, therefore, readily applied. These provide for resolving the global scale (large domain) with a relatively coarse mesh, while resolving the local scale (small domain) in high detail. As the total flow decreases, however, the flow pattern becomes tortuous and this requires a larger local-scale domain to obtain a converged solution. Therefore, a classical homogenization-based approach might not be feasible for simulation of very small flows. In order to study small flows, a model allowing feasibly-sized local domains, for really small flow rates, is developed. Realization was made possible by coupling the two scales with a stochastic element. Results from numerical experiments, show that the present model is in better agreement with the direct deterministic one than the conventional homogenization type of model, both quantitatively in terms of flow rate and qualitatively in reflecting the flow pattern.

Extracellular matrix: the gatekeeper of tumor angiogenesis

2019 ◽  
Vol 47 (5) ◽  
pp. 1543-1555 ◽  
Author(s):  
Maurizio Mongiat ◽  
Simone Buraschi ◽  
Eva Andreuzzi ◽  
Thomas Neill ◽  
Renato V. Iozzo
Keyword(s):  
Extracellular Matrix ◽  
Tumor Angiogenesis ◽  
Signaling Cascades ◽  
Cancer Growth ◽  
Cell Behavior ◽  
Metastatic Progression ◽  
Surface Receptors ◽  
The Matrix ◽  
Multiple Signaling

Abstract The extracellular matrix is a network of secreted macromolecules that provides a harmonious meshwork for the growth and homeostatic development of organisms. It conveys multiple signaling cascades affecting specific surface receptors that impact cell behavior. During cancer growth, this bioactive meshwork is remodeled and enriched in newly formed blood vessels, which provide nutrients and oxygen to the growing tumor cells. Remodeling of the tumor microenvironment leads to the formation of bioactive fragments that may have a distinct function from their parent molecules, and the balance among these factors directly influence cell viability and metastatic progression. Indeed, the matrix acts as a gatekeeper by regulating the access of cancer cells to nutrients. Here, we will critically evaluate the role of selected matrix constituents in regulating tumor angiogenesis and provide up-to-date information concerning their primary mechanisms of action.

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