scholarly journals Octree Optimized Micrometric Fibrous Microstructure Generation for Domain Reconstruction and Flow Simulation

Entropy ◽  
2021 ◽  
Vol 23 (9) ◽  
pp. 1156
Author(s):  
Nesrine Aissa ◽  
Louis Douteau ◽  
Emmanuelle Abisset-Chavanne ◽  
Hugues Digonnet ◽  
Patrice Laure ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Element Formulation ◽  
Fibrous Materials ◽  
Stabilized Finite Element ◽  
Numerical Tools ◽  
Monolithic Approach

Over recent decades, tremendous advances in the field of scalable numerical tools and mesh immersion techniques have been achieved to improve numerical efficiency while preserving a good quality of the obtained results. In this context, an octree-optimized microstructure generation and domain reconstruction with adaptative meshing is presented and illustrated through a flow simulation example applied to permeability computation of micrometric fibrous materials. Thanks to the octree implementation, the numerous distance calculations in these processes are decreased, thus the computational complexity is reduced. Using the parallel environment of the ICI-tech library as a mesher and a solver, a large scale case study is performed. The study is applied to the computation of the full permeability tensor of a three-dimensional microstructure containing 10,000 fibers. The considered flow is a Stokes flow and it is solved with a stabilized finite element formulation and a monolithic approach.

scholarly journals Automatic delineation of debris-covered glaciers using InSAR coherence derived from X-, C- and L-band radar data: a case study of Yazgyl Glacier

2018 ◽  
Vol 64 (247) ◽  
pp. 811-821 ◽  
Author(s):  
STEFAN LIPPL ◽  
SAURABH VIJAY ◽  
MATTHIAS BRAUN
Keyword(s):  
Large Scale ◽  
Window Size ◽  
Radar Data ◽  
Morphological Operations ◽  
L Band ◽  
Surrounding Areas ◽  
Coherence Estimation ◽  
The Impact

ABSTRACTDespite their importance for mass-balance estimates and the progress in techniques based on optical and thermal satellite imagery, the mapping of debris-covered glacier boundaries remains a challenging task. Manual corrections hamper regular updates. In this study, we present an automatic approach to delineate glacier outlines using interferometrically derived synthetic aperture radar (InSAR) coherence, slope and morphological operations. InSAR coherence detects the temporally decorrelated surface (e.g. glacial extent) irrespective of its surface type and separates it from the highly coherent surrounding areas. We tested the impact of different processing settings, for example resolution, coherence window size and topographic phase removal, on the quality of the generated outlines. We found minor influence of the topographic phase, but a combination of strong multi-looking during interferogram generation and additional averaging during coherence estimation strongly deteriorated the coherence at the glacier edges. We analysed the performance of X-, C- and L- band radar data. The C-band Sentinel-1 data outlined the glacier boundary with the least misclassifications and a type II error of 0.47% compared with Global Land Ice Measurements from Space inventory data. Our study shows the potential of the Sentinel-1 mission together with our automatic processing chain to provide regular updates for land-terminating glaciers on a large scale.

scholarly journals Validation Methods of Geometric 3D-CityGML Data for Urban Wind Simulations

2019 ◽  
Vol 128 ◽  
pp. 10006 ◽  
Author(s):  
Younis Saida Saeedrashed ◽  
Ali Cemal Benim
Keyword(s):  
Healing Process ◽  
Flow Simulation ◽  
Software Tools ◽  
Geometrical Structures ◽  
Geometric Data ◽  
3D City Model ◽  
City Model ◽  
Closed Shells

Validation of the geometric data such as 3D city model is quite crucial for simulation tasks, since the simulation process strongly correlates to the quality of geometric data being meshed. Validation methodology and healing of the 3D city models using different tools are presented. The most common inherited geometrical errors are checked and analyzed. Accordingly, an appropriate healing process to the case study is performed, which illustrates that the required closed solids and closed shells are obtained within the geometrical structures of the 3D city model being processed. Also, in this paper we compare some related open source and commercial software tools for the validation and healing process. It is noticed that they differ from each other in performing the required healing process. Some of them are quite good in healing specific errors, whereas not successful in healing the rest of errors. The goal of the paper is to obtain more understanding of the geometric validation and healing capabilities of various software tools, and the qualities of generated meshes, to lead to more effective and reliable simulations in the field of urban wind flow simulation.

A Benchmark Comparison of Coupled and Segregated Iterative SUPG Finite Element Formulation for Incompressible Flow

2006 ◽  
Author(s):  
Jianhui Xie ◽  
R. S. Amano
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Cost Effective ◽  
Element Formulation ◽  
Application Problem ◽  
The Individual ◽  
Solution Efficiency ◽  
Fully Coupled

In fluid flow and heat transfer, the finite element based fully coupling solution for all conservation equations is cost effective for most of the two dimensional, isothermal problems, but suffers in the storage and solution efficiency for large three dimensional problems. The segregated solution algorithm has been designed to address large scale simulation with avoiding the direct formulation of a global matrix. There is trade-off between performing a large number of less expensive iterations by segregated solvers compared to less number of more expensive fully coupled solvers. In this paper, a Finite Element based scheme based on preconditioned GMRES coupled algorithm and SUPG (Streamline Upwind Petrov-Galerkin) pressure prediction/correction segregated formulations have been discussed to solve the steady Navier-Stokes equations. A systematic comparison and benchmark between the segregated and fully coupled formulation has been presented to evaluate the individual benefits and strengths of the coupling and segregated procedure by studying lid-driven cavity problem and large industry application problem with respect to the system storage and solution convergence.

Can the Deforestation Breeze Change the Rainfall in Amazonia? A Case Study for the BR-163 Highway Region

2010 ◽  
Vol 14 (18) ◽  
pp. 1-25 ◽  
Author(s):  
Sandra I. Saad ◽  
Humberto R. da Rocha ◽  
Maria A. F. Silva Dias ◽  
Rafael Rosolem
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Three Dimensional ◽  
Atmospheric Modeling ◽  
Thermal Cell ◽  
Soil Wetness ◽  
Soil Dryness ◽  
Regional Atmospheric Modeling ◽  
The Impact

Abstract The authors simulated the effects of Amazonian mesoscale deforestation in the boundary layer and in rainfall with the Brazilian Regional Atmospheric Modeling System (BRAMS) model. They found that both the area and shape (with respect to wind incidence) of deforestation and the soil moisture status contributed to the state of the atmosphere during the time scale of several weeks, with distinguishable patterns of temperature, humidity, and rainfall. Deforestation resulted in the development of a three-dimensional thermal cell, the so-called deforestation breeze, slightly shifted downwind to large-scale circulation. The boundary layer was warmer and drier above 1000-m height and was slightly wetter up to 2000-m height. Soil wetness affected the circulation energetics proportionally to the soil dryness (for soil wetness below ∼0.6). The shape of the deforestation controlled the impact on rainfall. The horizontal strips lined up with the prevailing wind showed a dominant increase in rainfall, significant up to about 60 000 km2. On the other hand, in the patches aligned in the opposite direction (north–south), there was both increase and decrease in precipitation in two distinct regions, as a result of clearly separated upward and downward branches, which caused the precipitation to increase for patches up to 15 000 km2. The authors’ estimates for the size of deforestation impacting the rainfall contributed to fill up the low spatial resolution in other previous studies.

scholarly journals How to Record Current Events like an Archaeologist

2021 ◽  
pp. 1-8
Author(s):  
Matthew Magnani ◽  
Anatolijs Venovcevs ◽  
Stein Farstadvoll ◽  
Natalia Magnani
Keyword(s):  
Material Culture ◽  
Large Scale ◽  
Three Dimensional ◽  
Social Phenomena ◽  
Field Methods ◽  
State Response ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Current Events

ABSTRACT This article shows how to record current events from an archaeological perspective. With a case study from the COVID-19 pandemic in Norway, we provide accessible tools to document broad spatial and behavioral patterns through material culture as they emerge. Stressing the importance of ethical engagement with contemporary subjects, we adapt archaeological field methods—including geolocation, photography, and three-dimensional modeling—to analyze the changing relationships between materiality and human sociality through the crisis. Integrating data from four contributors, we suggest that this workflow may engage broader publics as anthropological data collectors to describe unexpected social phenomena. Contemporary archaeological perspectives, deployed in rapid response, provide alternative readings on the development of current events. In the presented case, we suggest that local ways of coping with the pandemic may be overshadowed by the materiality of large-scale corporate and state response.

scholarly journals Contextual Contracts for Component-Based Resource Abstraction in a Cloud of HPC Services

2019 ◽  
Author(s):  
Wagner Al Alam ◽  
Francisco Carvalho Junior
Keyword(s):  
Cloud Computing ◽  
Parallel Computing ◽  
Large Scale ◽  
Matrix Multiplication ◽  
Small Scale ◽  
Computing Systems ◽  
Computing Platform ◽  
Computing Platforms

The efforts to make cloud computing suitable for the requirements of HPC applications have motivated us to design HPC Shelf, a cloud computing platform of services for building and deploying parallel computing systems for large-scale parallel processing. We introduce Alite, the system of contextual contracts of HPC Shelf, aimed at selecting component implementations according to requirements of applications, features of targeting parallel computing platforms (e.g. clusters), QoS (Quality-of-Service) properties and cost restrictions. It is evaluated through a small-scale case study employing a componentbased framework for matrix-multiplication based on the BLAS library.

Ensuring Quality of a Large-Scale Online Assessment for Nursing Students in the 21st Century

2020 ◽  
Vol 11 (3) ◽  
pp. 49-65
Author(s):  
Emily Ng K.L.
Keyword(s):  
Nursing Education ◽  
Nursing Students ◽  
21St Century ◽  
Large Scale ◽  
Multiple Choice ◽  
Online Assessment ◽  
Full Potential ◽  
Validity And Reliability

The resources and time constraints of assessing large classes are always weighed up against the validity, reliability, and learning outcomes of the assessment tasks. With the digital revolution in the 21st Century, educators can benefit from computer technology to carry out a large-scale assessment in higher education more efficiently. In this article, an in-depth case study of a nursing school that has integrated online assessment initiatives into their nursing program. To assess a large class of first-year nursing students, a series of non-proctored multiple-choice online quizzes are administered using a learning management system. Validity and reliability are commonly used to measure the quality of an assessment. The aim of the present article to analyze these non-proctored multiple-choice online assessments in the context of content validity and reliability. We use this case study to examine online assessment in nursing education, exploring the benefits and challenges. We conclude that instructors have to determine how to use the full potential of online assessment as well as ensure validity and reliability.

Ensuring Quality of a Large-Scale Online Assessment for Nursing Students in the 21st Century

2021 ◽  
pp. 26-39
Author(s):  
Emily Ng K.L.
Keyword(s):  
Nursing Students ◽  
21St Century ◽  
Large Scale ◽  
Multiple Choice ◽  
Online Assessment ◽  
Full Potential ◽  
Validity And Reliability ◽  
Online Assessments

The resources and time constraints of assessing large classes are always weighed up against the validity, reliability, and learning outcomes of the assessment tasks. With the digital revolution in the 21st Century, educators can benefit from computer technology to carry out a large-scale assessment in higher education more efficiently. In this article, an in-depth case study of a nursing school that has integrated online assessment initiatives into their nursing program. To assess a large class of first-year nursing students, a series of non-proctored multiple-choice online quizzes are administered using a learning management system. Validity and reliability are commonly used to measure the quality of an assessment. The aim of the present article to analyze these non-proctored multiple-choice online assessments in the context of content validity and reliability. We use this case study to examine online assessment in nursing education, exploring the benefits and challenges. We conclude that instructors have to determine how to use the full potential of online assessment as well as ensure validity and reliability.

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