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Modeling and simulation of human upper airway

作者： Liu, Zishun Xu, Xiangguo Lim, Franco Fang Jeng Luo, Xiaoyu Van Hirtum, Annemie Hill, N.A. Institute of High Performance Computing Fusionopolis Way 16-16 Connexis 138632 Singapore Engineering Science Programme National University of Singapore Singapore 117576 Singapore Department of Mathematics University of Glasgow Glasgow G12 8QW United Kingdom Département Parole et Cognition GIPSA-Lab University of Grenoble CNRS 5216 46 Av. Felix Viallet Grenoble 38031 France

ISBN: (纸本)9783540790389

Snoring might indicate the first stage of the Obstructive Sleep Apnea (OSA) syndrome, and has received much attention in recent years. Previous studies on snoring have shown that upper airway narrowing, collapse, and resistance are predisposing factors for snoring and OSA. However, further research work is needed to understand the mechanisms of snoring. Although there have been many CFD studies modeling nasal turbulence, the larynx and vocal folds, most are limited to lumped one- or two- dimensional cases, or three-dimensional problems with over-simplified physics, e.g. rigid rather than flexible walls. In this study, we address the impact of fluid-structure interactions by using a three-dimensional numerical simulation of an experimental upper airway model, which is constructed to mimic the interaction of the deformation of the soft palate and adjacent tissues with a pressurized airflow (breathing) during sleep. The model consists of a deformable structure domain and its associated airflow domain. The results of the numerical simulation are compared with the experimental data. In addition, Interesting flow fields and pressure distributions are revealed. The fluid structure interaction model can be developed further to study the more realistic human upper airway problems. © 2010 International Federation for Medical and Biological engineering.

关键词： Fluid structure interaction

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Large-Scale Direct Numerical Simulations of Turbulence Using GPUs and Modern Fortran

arXiv

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arXiv 2022年

作者： Karp, Martin Massaro, Daniele Jansson, Niclas Hart, Alistair Wahlgren, Jacob Schlatter, Philipp Markidis, Stefano Department of Computer Science KTH Royal Institute of Technology Stockholm Sweden Engineering Mechanics KTH Royal Institute of Technology Stockholm Sweden PDC Centre for High Performance Computing KTH Royal Institute of Technology Stockholm Sweden United Kingdom

We present our approach to making direct numerical simulations of turbulence with applications in sustainable shipping. We use modern Fortran and the spectral element method to leverage and scale on supercomputers powered by the Nvidia A100 and the recent AMD Instinct MI250X GPUs, while still providing support for user software developed in Fortran. We demonstrate the efficiency of our approach by performing the world’s first direct numerical simulation of the flow around a Flettner rotor at Re=30’000 and its interaction with a turbulent boundary layer. We present one of the first performance comparisons between the AMD Instinct MI250X and Nvidia A100 GPUs for scalable computational fluid dynamics. Our results show that one MI250X offers performance on par with two A100 GPUs and has a similar power efficiency. Copyright © 2022, The Authors. All rights reserved.

关键词： Numerical models

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On the Development of Global Plasma-Ionosphere FDTD Algorithms for Electromagnetic Calculations in the Earth- Ionosphere System

On the Development of Global Plasma-Ionosphere FDTD Algorith...

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International Conference on Electromagnetics in Advanced Applications

作者： Yaxin Yu Jamesina J. Simpson Erping Li Institute of High Performance Computing Agency for Science Technology and Research (A*STAR) 1 Fusionopolis Way #16-16 Connexis North Tower Singapore 138632 Electrical and Computer Engineering Department University of New Mexico Albuquerque NM 87106 USA

ISBN: (纸本)9781467303330

This paper reports the development of global FDTD models incorporated with a quasi-real anisotropic ionosphere consisting of magnetized cold plasmas. Compared to the existing global models utilizing simple conductivity ionospheric profiles, the algorithms reported in this paper can sufficiently extend the global-scale electromagnetic simulations to much higher altitudes as the physics introduced by the spatially-varied ionospheric plasmas and the geomagnetic field can be fully included in calculations.

关键词： paper reports global FDTD extend the global-scale

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Enhancing countries' fitness with recommender systems on the international trade network

arXiv

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arXiv 2019年

作者： Liao, Hao Wu, Xing-Tong Vidmer, Alexandre Huang, Xiao-Min Liu, Ming-Kai Zhou, Mingyang Zhang, Yi-Cheng National Engineering Laboratory for Big Data System Computing Technology Guangdong Province Key Laboratory of Popular High Performance Computers College of Computer Science and Software Engineering Shenzhen University Shenzhen518060 China Department of Physics University of Fribourg Fribourg1700 Switzerland

Prediction is one of the major challenges in complex systems. The prediction methods have shown to be effective predictors of the evolution of networks. These methods can help policy makers to solve practical problems successfully and make better strategy for the future. In this work, we focus on exporting countries' data of the international trading network. A recommendation system is then used to identify the products corresponding to the production capacity of each individual country, but are somehow overlook by the country. Then, we simulate the evolution of the country's fitness if it would have followed the recommendations. The result of this work is the combination combine these two methods to provide insights to countries on how to enhance the diversification of their exported products in a scientific way and improve national competitiveness significantly, especially for developing countries. Copyright © 2019, The Authors. All rights reserved.

关键词： Recommender systems

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Analysis on the effectiveness of the 20-H rule using numerical simulation technique

Analysis on the effectiveness of the 20-H rule using numeric...

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IEEE International Symposium on Electromagnetic Compatibility (EMC)

作者： Er-Ping Li Wei-Liang Yuan Jiang Yi Le-Wei Li M.I. Montrose EMC Division Institute of High Performance Computing Singapore Temasek Lab National University of Singapore Singapore Department of Electrical and Computer Engineering National University of Singapore Singapore Montrose Compliance Services Inc. Santa Clara CA USA

With increasing demand for higher operating frequencies, printed circuit board (PCB) designers are faced with numerous obstacles during the design cycle. The 20-H rule is one layout technique that is recommended to minimize radiated fields propagating from the edges of a PCB. These fields, either magnetic or electric, may corrupt adjacent cable assemblies, sheet metal enclosures and aperture openings. The magnitude of this design rule is investigated herein using the numerical electromagnetic simulation method, finite difference time domain (FDTD). In addition, an analysis on whether benefits exist from use of the 20-H rule is examined. The significance to the field of EMC lies in presenting, for the first time, an exhaustive analysis that took over one year to achieve using various configurations and frequencies. A rigorous analysis indicates that benefits do occur from use of the 20-H rule, but only when implemented in certain applications.

关键词： Numerical simulation Frequency Finite difference methods Printed circuits Electromagnetic propagation Magnetic domains Assembly Apertures Electromagnetic radiation Time domain analysis

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Modeling recycle: a case study in the industrial use of measurement and modeling

Modeling recycle: a case study in the industrial use of meas...

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International computer performance and Dependability Symposium

作者： L.M. Malhis S.C. West L.A. Kant W.H. Sanders Storage Systems Division IBM Corporation Tucson AZ USA Department of Electrical and Computer Engineering University of Arizona Tucson Tucson AZ USA Department of Electrical and Computer Engineering University of Arizona Tucson Tustin AZ USA Center for Reliable and High-Performance Computing Coordinated Science Laboratory University of Illinois Urbana IL USA

Large-scale data storage systems rely on magnetic tape cartridges to store millions of data objects. As these tapes age, the resident data objects become invalid; consequently, less and less of the tape potential capacity is effectively utilized. To address this problem, data storage systems have a facility, called "recycle" in this paper, that transfers valid data objects from sparsely populated tapes onto new tapes, thus creating empty tapes for reuse. A high performance recycle process is needed to keep the number of tape cartridges to a minimum, and to maintain a continuous supply of empty tapes for storing newly created data objects. The performance of such processes is not easy to determine, and depends strongly on the data stored on the tapes, the speed and characteristics of the computer on which recycle is executed, and the nature of the algorithms themselves. This paper documents an extensive effort to evaluate a proposed recycle algorithm, using held workload data, laboratory measurements, and modeling. The results of the study were used to improve the recycle process, and were later verified through field trials. In addition yielding the results themselves, the effort illustrated that modeling and measurement, in an industrial setting, can indeed be used successfully in the design process.< >

关键词： Recycling computer aided software engineering Large-scale systems Data storage systems laboratories Magnetic field measurement Process design Coordinate measuring machines Electric variables measurement Area measurement

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3d Microvascular Reconstruction in Retinal Oct Angiography Images Via Domain-Adaptive Learning

SSRN

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SSRN 2023年

作者： Zhang, Jiong Yu, Shuai Liu, Yonghuai Zhang, Dan Xie, Jianyang Chen, Tao Zheng, Yalin Fu, Huazhu Zhao, Yitian Institute of Biomedical Engineering Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo China Department of Computer Science Edge Hill University United Kingdom School of Cyber Science and Engineering Ningbo University of Technology Ningbo China Department of Eye and Vision Science University of Liverpool Liverpool United Kingdom Institute of High Performance Computing A*STAR Singapore

Optical Coherence Tomography Angiography (OCTA) is a non-invasive imaging technique that enables the acquisition of 3D depth-resolved information with micrometer resolution, facilitating the diagnosis of various eye-related diseases. In OCTA-based image analysis, 2D en face projected images are commonly used for quantifying microvascular changes, while the 3D images with rich depth information remains largely unexplored. This is mainly due to that direct 3D vessel reconstruction faces several challenges, including projection artifacts, complex vessel topology, and high computational cost. These limitations hinder comprehensive microvascular analysis and may obscure potentially vital 3D vessel biomarkers. In this study, we propose a novel method for 3D reconstruction of retinal microvasculature using 2D en face images. Our approach capitalizes on a elaborately generated 2D OCTA depth map for vessel reconstruction, thus eliminating the need for unavailable 3D volumetric data in certain retinal imaging devices. More specifically, we first build a structure-guided depth prediction network which incorporates a domain adaptation module to evaluate the depth maps obtained from different OCTA imaging devices. A point-cloud-to-surface reconstruction method is then utilized to reconstruct the corresponding 3D retinal vessels, based on the predicted depth maps and 2D vascular information. Experimental results demonstrate the superior performance of our method in comparison to existing state-of-the-art techniques. Furthermore, we extract 3D vessel-related features to assess disease correlation and classification, effectively evaluating the potential of our method for guiding subsequent clinical analysis. The results show promise of exploring 3D microvascular analysis for early diagnosis of various eye-related diseases. © 2023, The Authors. All rights reserved.

关键词： Angiography

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Modeling, Mesh Generation, and Adaptive Numerical Methods for Partial Differential Equations 1

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丛书名： The IMA Volumes in Mathematics and its Applications

1995年

作者： Ivo Babuska William D. Henshaw Joseph E. Oliger Joseph E. Flaherty John E. Hopcroft Tayfun Tezduyar

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Camera movement for chasing a subject with unknown behavior based on real-time viewpoint goodness evaluation

Camera movement for chasing a subject with unknown behavior ...

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作者： Ozaki, Maya Gobeawan, Like Kitaoka, Shinya Hamazaki, Hirofumi Kitamura, Yoshifumi Lindeman, Robert W. Human Interface Engineering Lab. Osaka University 2-1 Yamadaoka 565-0871 Suita Osaka Japan Advanced Computing Institute of High Performance Computing Fusionopolis 1 Fusionopolis Way 138632 Singapore Singapore Sharp Corporation 22-22 Nagaike-cho 545-8522 Abeno-ku Osaka Japan Research Institute of Electrical Communication Tohoku University 2-1-1 Katahira 980-8577 Aoba-ku Sendai Japan Computer Science Worcester Polytechnic Institute 100 Institute Road Worcester MA 01609-2280 United States

We propose a method that automatically generates a smooth chase camera movement to follow a subject, a user-controlled character or a character with unknown behaviors, in a 3D environment freely in real time. We consider three objectives in generating the smooth-camera movement: to avoid collisions with obstacles, to avoid subject occlusions, and to choose a good viewpoint for looking at the subject. We evaluate the goodness of viewpoints by using a viewpoint entropy map and choose the best viewpoint as the goal position of the camera in real time. Afterwards, we move the camera toward the goal position by following the shortest path, found by the A* algorithm, on a roadmap graph. The resulting camera movement has a high degree of freedom and fulfills the three objectives above. Our method is effective for third-person-view 3D applications in tracking the real-time movement of user-controlled characters in exploring a 3D environment. © Springer-Verlag 2010.

关键词： Motion planning

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Compressed Indexes for Fast Search of Semantic Data

arXiv

引用

arXiv 2019年

作者： Perego, Raffaele Pibiri, Giulio Ermanno Venturini, Rossano High Performance Computing Lab ISTI-CNR Area della Ricerca di Pisa Via Giuseppe Moruzzi 1 Pisa56126 Italy Department of Computer Science University of Pisa Viale Largo Bruno Pontecorvo 3 Pisa56127 Italy

The sheer increase in volume of RDF data demands efficient solutions for the triple indexing problem, that is to devise a compressed data structure to compactly represent RDF triples by guaranteeing, at the same time, fast pattern matching operations. This problem lies at the heart of delivering good practical performance for the resolution of complex SPARQL queries on large RDF datasets. In this work, we propose a trie-based index layout to solve the problem and introduce two novel techniques to reduce its space of representation for improved effectiveness. The extensive experimental analysis, conducted over a wide range of publicly available real-world datasets, reveals that our best space/time trade-off configuration substantially outperforms existing solutions at the state-of-the-art, by taking 30 – 60% less space and speeding up query execution by a factor of 2 – 81×. Copyright © 2019, The Authors. All rights reserved.

关键词： Large dataset

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