scholarly journals Multiscale computing for science and engineering in the era of exascale performance

2019 ◽  
Vol 377 (2142) ◽  
pp. 20180144 ◽  
Author(s):  
Alfons G. Hoekstra ◽  
Bastien Chopard ◽  
David Coster ◽  
Simon Portegies Zwart ◽  
Peter V. Coveney
Keyword(s):  
Multiscale Model ◽  
Multiscale Simulation ◽  
Multiscale Models ◽  
Theme Issue ◽  
Science And Engineering ◽  
High Performing ◽  
The Face ◽  
Strong Scaling ◽  
Computing Environments ◽  
Modelling Simulation

In this position paper, we discuss two relevant topics: (i) generic multiscale computing on emerging exascale high-performing computing environments, and (ii) the scaling of such applications towards the exascale. We will introduce the different phases when developing a multiscale model and simulating it on available computing infrastructure, and argue that we could rely on it both on the conceptual modelling level and also when actually executing the multiscale simulation, and maybe should further develop generic frameworks and software tools to facilitate multiscale computing. Next, we focus on simulating multiscale models on high-end computing resources in the face of emerging exascale performance levels. We will argue that although applications could scale to exascale performance relying on weak scaling and maybe even on strong scaling, there are also clear arguments that such scaling may no longer apply for many applications on these emerging exascale machines and that we need to resort to what we would call multi-scaling . This article is part of the theme issue ‘Multiscale modelling, simulation and computing: from the desktop to the exascale’.

scholarly journals Multiscale modelling, simulation and computing: from the desktop to the exascale

2019 ◽  
Vol 377 (2142) ◽  
pp. 20180355 ◽  
Author(s):  
Alfons G. Hoekstra ◽  
Simon Portegies Zwart ◽  
Peter V. Coveney
Keyword(s):  
High Performance ◽  
Multiscale Modelling ◽  
Biomedical Sciences ◽  
Theme Issue ◽  
Short Contribution ◽  
Computing Systems ◽  
The Face ◽  
Computing Environments ◽  
Performance Computing ◽  
Modelling Simulation

This short contribution introduces a theme issue dedicated to ‘Multiscale modelling, simulation and computing: from the desktop to the exascale’. It holds a collection of articles presenting cutting-edge research in generic multiscale modelling and multiscale computing, and applications thereof on high-performance computing systems. The special issue starts with a position paper to discuss the paradigm of multiscale computing in the face of the emerging exascale, followed by a review and critical assessment of existing multiscale computing environments. This theme issue provides a state-of-the-art account of generic multiscale computing, as well as exciting examples of applications of such concepts in domains ranging from astrophysics, via material science and fusion, to biomedical sciences. This article is part of the theme issue ‘Multiscale modelling, simulation and computing: from the desktop to the exascale’.

Recent Development in Multiscale Simulation of Mechanical Properties at Material Interface

2010 ◽  
Vol 146-147 ◽  
pp. 491-494
Author(s):  
Ning Bo Liao ◽  
Miao Zhang ◽  
Rui Jiang
Keyword(s):  
Mechanical Properties ◽  
Multiscale Model ◽  
Multiscale Simulation ◽  
Material Interfaces ◽  
Material Interface ◽  
Multi Scale ◽  
Simulation Techniques ◽  
Hierarchical Nature ◽  
Feature Scale

For nanoscale devices and structures, interface phenomena often dominate their overall thermal behavior. The feature scale of material interfaces usually originate from nanometer length and present a hierarchical nature. Considering to the limitations of the continuum mechanics on the characterization of nano-scale, the multiscale model featuring the interface could be very important in materials design. The purpose of this review is to discuss the applications of multiscale modeling and simulation techniques to study the mechanical properties at materials interface. It is concluded that a multi-scale scheme is needed for this study due to the hierarchical characteristics of interface.

Probabilistic Multiscale Models for Fracture Analysis of Functionally Graded Composites

2008 ◽  
Author(s):  
Arindam Chakraborty ◽  
Sharif Rahman
Keyword(s):  
Driving Forces ◽  
Multiscale Model ◽  
Fracture Analysis ◽  
Computational Effort ◽  
Functionally Graded ◽  
Stochastic Methods ◽  
Multiscale Models ◽  
Particle Volume ◽  
Two Phase ◽  
Microscale Model

This paper reports three multiscale models, including sequential, invasive, and concurrent models, for fracture analysis of a crack in a two-phase, functionally graded composite. The models involve stochastic description of the particle volume fractions, particle locations, and constituent material properties; a two-scale algorithm including microscale and macroscale analyses for determining crack-driving forces; and two stochastic methods for fracture reliability analysis. Numerical results indicate that the sequential and invasive multiscale models are the most computationally inexpensive models available, but they may not produce acceptable probabilistic characteristics of stress-intensity factors or accurate probability of fracture initiation. The concurrent multiscale model is sufficiently accurate, gives probabilistic solutions very close to those generated from the microscale model, and can reduce the computational effort of the latter model by more than a factor of two. In addition, the concurrent multiscale model predicts crack trajectory as accurately as the microscale model.

Thermodynamics in solid mechanics: a commentary

2005 ◽  
Vol 363 (1836) ◽  
pp. 2465-2477 ◽  
Author(s):  
Graham Baker
Keyword(s):  
Physical Interpretation ◽  
Solid Mechanics ◽  
Material Behaviour ◽  
Theme Issue ◽  
Science And Engineering ◽  
Knowing That ◽  
Real Material ◽  
Nonlinear Solid Mechanics ◽  
The Subject ◽  
Thermodynamic Processes

This commentary on thermodynamics in solid mechanics aims to provide an overview of the main concepts of thermodynamic processes as they apply to, and may be exploited for, studies in nonlinear solid mechanics. We give a descriptive commentary on the (physical) interpretation of these concepts, and relate these where appropriate to behaviour of solids under thermo-mechanical conditions. The motivation is firstly that students of solid mechanics have often had less exposure to thermodynamics than those in other branches of science and engineering, yet there is great value in analytical formulations of material behaviour derived from the principles of thermodynamics. It also sets the contributions in this Theme Issue in context. Along with the deliberately descriptive treatment of thermodynamics, we do outline the main mathematical statements that define the subject, knowing that full details are provided by the authors in their corresponding contributions to this issue. The commentary ends on a lighter note. In order to aid understanding and to stimulate discussion of thermodynamics in solid mechanics, we have invented a number of very basic and completely fictitious materials. These have strange and extreme behaviours that describe certain thermodynamics concepts, such as entropy, in isolation from the complexities of real material behaviour.

scholarly journals High performance leadership in unusually challenging educational circumstances

2015 ◽  
Vol 3 (1) ◽  
pp. 28-49 ◽  
Author(s):  
Andy Hargreaves ◽  
Alma Harris
Keyword(s):  
High Performance ◽  
Educational Achievement ◽  
Limited Resources ◽  
Short Term ◽  
Past Performance ◽  
High Performing ◽  
The Face ◽  
Oecd Pisa ◽  
And Performance

This paper draws on findings from the results of a study of leadership in high performing organizations in three sectors. Organizations were sampled and included on the basis of high performance in relation to no performance, past performance, performance among similar peers and performance in the face of limited resources or challenging circumstances. The paper concentrates on leadership in four schools that met the sample criteria.  It draws connections to explanations of the high performance ofEstoniaon the OECD PISA tests of educational achievement. The article argues that leadership in these four schools that performed above expectations comprised more than a set of competencies. Instead, leadership took the form of a narrative or quest that pursued an inspiring dream with relentless determination; took improvement pathways that were more innovative than comparable peers; built collaboration and community including with competing schools; and connected short-term success to long-term sustainability.

scholarly journals Reduced Order Multiscale Simulation of Diffuse Damage in Concrete

2021 ◽  
Author(s):  
Giao Vu ◽  
Fabian Diewald ◽  
Jithender J. Timothy ◽  
Christoph Gehlen ◽  
Günther Meschke
Keyword(s):  
Early Stage ◽  
Concrete Specimen ◽  
Multiscale Model ◽  
Multiscale Simulation ◽  
Scale Model ◽  
Compression Tests ◽  
Reduced Order ◽  
Damage In Concrete ◽  
Failure Precursors ◽  
Mortar Matrix

Damage in concrete structures initiates as the growth of diffuse microcracks that is followed by damage localisation and eventually leads to structural failure. Weak changes such as diffuse microcracking processes are failure precursors. Identification and characterisation of these failure precursors at an early stage of concrete degradation and application of suitable precautionary measures will considerably reduce the costs of repair and maintenance. To this end, a reduced order multiscale model for simulating microcracking-induced damage in concrete at the mesoscale levelis proposed. The model simulates the propagation of microcracks in concrete using a two-scale computational methodology. First, a realistic concrete specimen that explicitly resolves the coarse aggregates in a mortar matrix was generated at the mesoscale. Microcrack growth in the mortar matrix is modelled using a synthesis of continuum micromechanics and fracture mechanics. Model order reduction of the two-scale model is achieved using clustering technique. Model predictions are calibrated and validated using uniaxial compression tests performed in the laboratory.

scholarly journals Quantitative Comparison of High- and Low-Performing Teams in a Design Task Subject to Drastic Changes

2014 ◽  
Author(s):  
Christopher McComb ◽  
Jonathan Cagan ◽  
Kenneth Kotovsky
Keyword(s):  
Design Space ◽  
New Technology ◽  
Problem Formulation ◽  
Target Area ◽  
Design Data ◽  
Design Task ◽  
High Performing ◽  
Engineering Teams ◽  
Solution Strategies ◽  
The Face

Many design tasks are subject to changes in goals or constraints. For instance, a client might modify specifications after design has commenced, or a competitor may introduce a new technology or feature. A design team often cannot anticipate such changes, yet they pose a considerable challenge. This paper presents a study where engineering teams sought to solve a design task that was subject to two large, unexpected changes in problem formulation that occurred during problem solving. Continuous design data was collected to observe how the designers responded to the changes. We show that high- and low-performing teams demonstrated very different approaches to solving the problem and overcoming the changes. In particular, high-performing teams achieved simple designs and extensively explored small portions of the design space; low-performing teams explored complex designs with little exploration around a target area of the design space. These strategic differences are interpreted with respect to cognitive load theory and goal theory. The results raise questions as to the relationship between characteristics of design problems and solution strategies. In addition, an attempt at increasing the teams’ resilience in the face of unexpected changes is introduced by encouraging early divergent search.

scholarly journals Uncertainty quantification patterns for multiscale models

2021 ◽  
Vol 379 (2197) ◽  
Author(s):  
D. Ye ◽  
L. Veen ◽  
A. Nikishova ◽  
J. Lakhlili ◽  
W. Edeling ◽  
...  
Keyword(s):  
Decision Making ◽  
Uncertainty Quantification ◽  
Computational Models ◽  
Building Blocks ◽  
Computational Science ◽  
Proof Of Concept ◽  
Multiscale Models ◽  
Theme Issue ◽  
Multi Scale ◽  
Speed Up

Uncertainty quantification (UQ) is a key component when using computational models that involve uncertainties, e.g. in decision-making scenarios. In this work, we present uncertainty quantification patterns (UQPs) that are designed to support the analysis of uncertainty in coupled multi-scale and multi-domain applications. UQPs provide the basic building blocks to create tailored UQ for multiscale models. The UQPs are implemented as generic templates, which can then be customized and aggregated to create a dedicated UQ procedure for multiscale applications. We present the implementation of the UQPs with multiscale coupling toolkit Multiscale Coupling Library and Environment 3. Potential speed-up for UQPs has been derived as well. As a proof of concept, two examples of multiscale applications using UQPs are presented. This article is part of the theme issue ‘Reliability and reproducibility in computational science: implementing verification, validation and uncertainty quantification in silico ’.

scholarly journals Optimizing spatial and seasonal deployment of vaccination campaigns to eliminate wildlife rabies

2019 ◽  
Vol 374 (1776) ◽  
pp. 20180280 ◽  
Author(s):  
Laurie Baker ◽  
Jason Matthiopoulos ◽  
Thomas Müller ◽  
Conrad Freuling ◽  
Katie Hampson
Keyword(s):  
Infectious Disease ◽  
Plant Pathogens ◽  
Herd Immunity ◽  
Disease Outbreaks ◽  
Vaccination Strategy ◽  
Theme Issue ◽  
Infectious Disease Outbreaks ◽  
Control Programmes ◽  
The Face ◽  
And Control

Understanding how the spatial deployment of interventions affects elimination time horizons and potential for disease re-emergence has broad application to control programmes targeting human, animal and plant pathogens. We previously developed an epidemiological model that captures the main features of rabies spread and the impacts of vaccination based on detailed records of fox rabies in eastern Germany during the implementation of an oral rabies vaccination (ORV) programme. Here, we use simulations from this fitted model to determine the best vaccination strategy, in terms of spatial placement and timing of ORV efforts, for three epidemiological scenarios representative of current situations in Europe. We found that consecutive and comprehensive twice-yearly vaccinations across all regions rapidly controlled and eliminated rabies and that the autumn campaigns had the greater impact on increasing the probability of elimination. This appears to result from the need to maintain sufficient herd immunity in the face of large birth pulses, as autumn vaccinations reach susceptible juveniles and therefore a larger proportion of the population than spring vaccinations. Incomplete vaccination compromised time to elimination requiring the same or more vaccination effort to meet similar timelines. Our results have important practical implications that could inform policies for rabies containment and elimination in Europe and elsewhere. This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control’. This theme issue is linked with the earlier issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’.

scholarly journals Live human–robot interactive public demonstrations with automatic emotion and personality prediction

2019 ◽  
Vol 374 (1771) ◽  
pp. 20180026 ◽  
Author(s):  
Hatice Gunes ◽  
Oya Celiktutan ◽  
Evangelos Sariyanidi
Keyword(s):  
Facial Expressions ◽  
Humanoid Robot ◽  
Lessons Learned ◽  
Human Robot Interaction ◽  
Theme Issue ◽  
Science And Engineering ◽  
Robot Interaction ◽  
Personality Prediction ◽  
Human Participants ◽  
Public Demonstrations

Communication with humans is a multi-faceted phenomenon where the emotions, personality and non-verbal behaviours, as well as the verbal behaviours, play a significant role, and human–robot interaction (HRI) technologies should respect this complexity to achieve efficient and seamless communication. In this paper, we describe the design and execution of five public demonstrations made with two HRI systems that aimed at automatically sensing and analysing human participants’ non-verbal behaviour and predicting their facial action units, facial expressions and personality in real time while they interacted with a small humanoid robot. We describe an overview of the challenges faced together with the lessons learned from those demonstrations in order to better inform the science and engineering fields to design and build better robots with more purposeful interaction capabilities. This article is part of the theme issue ‘From social brains to social robots: applying neurocognitive insights to human–robot interaction’.

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