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arXiv 2024年

作者： Sikdar, Satyaki Venturini, Sara Charpignon, Marie-Laure Kumar, Sagar Rinaldi, Francesco Tudisco, Francesco Fortunato, Santo Majumder, Maimuna S. Luddy School of Informatics Computing and Engineering Indiana University BloomingtonIN United States Department of Computer Science Loyola University Chicago ChicagoIL United States Senseable City Laboratory Massachusetts Institute of Technology CambridgeMA United States Department of Mathematics "Tullio Levi-Civita" University of Padova Padova Italy Institute for Data Systems and Society Massachusetts Institute of Technology CambridgeMA United States Network Science Institute Northeastern University BostonMA United States School of Mathematics The University of Edinburgh Edinburgh United Kingdom School of Mathematics Gran Sasso Science Institute L’Aquila Italy Department of Pediatrics Harvard Medical School BostonMA United States Computational Health Informatics Program Boston Children’s Hospital BostonMA United States

Since the emergence of COVID-19, discussions of ongoing pandemic-related research have accounted for an unprecedented share of media coverage and debate in the public sphere1. The urgency of the pandemic forced researchers to operate on an accelerated timeline, as both policymakers and the public relied on the most current evidence to guide their decisions and behaviors. With high demand for rapid pandemic-related insights and lower barriers to entry via preprint servers, the volume of COVID-19 articles skyrocketed2. The pressing need for research triggered the participation of many researchers with expertise in the science of infectious disease outbreaks (‘outbreak scientists’), who were joined by researchers from other disciplines (‘bellwethers’) and more junior researchers still in training (‘newcomers’) with the common goal of advancing the frontiers of pandemic science and informing policy decisions3. Please see Box 1 for details of this taxonomy. © 2024, CC BY-NC-ND.

关键词： COVID-19

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Efficient multi-level hp-finite elements in arbitrary dimensions

arXiv

引用

arXiv 2021年

作者： Kopp, Philipp Rank, Ernst Calo, Victor M. Kollmannsberger, Stefan Computational Modeling and Simulation Technical University of Munich Germany Computation in Engineering Technical University of Munich Germany Institute for Advanced Study Technical University of Munich Germany Applied Mathematics School of Electrical Engineering Computing & Mathematical Science Faculty of Science and Engineering Curtin University Australia

We present an efficient algorithmic framework for constructing multi-level hp-bases that uses a data-oriented approach that easily extends to any number of dimensions and provides a natural framework for performance-optimized implementations. We only operate on the bounding faces of finite elements without considering their lower-dimensional topological features and demonstrate the potential of the presented methods using a newly written open-source library. First, we analyze a Fichera corner and show that the framework does not increase runtime and memory consumption when compared against the classical p-version of the finite element method. Then, we compute a transient example with dynamic refinement and derefinement, where we also obtain the expected convergence rates and excellent performance in computing time and memory usage. ©2022TheAuthor(s).*** (http://***/licenses/by/4.0/). © 2021, CC BY.

关键词： Finite element method

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A high-order finite element methods for nonlinear convection-diffusion equation on time-varying domain

arXiv

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arXiv 2021年

作者： Ma, Chuwen Zheng, Weiying LSEC NCMIS Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China School of Mathematical Science University of Chinese Academy of Sciences Beijing100049 China

A high-order finite element method is proposed to solve the nonlinear convection-diffusion equation on a time-varying domain whose boundary is implicitly driven by the solution of the equation. The method is semi-implicit in the sense that the boundary is traced explicitly with a high-order surface-tracking algorithm, while the convection-diffusion equation is solved implicitly with high-order backward differentiation formulas and fictitious-domain finite element methods. By numerical experiments on severely deforming domains, we show that optimal convergence orders are obtained in energy norm for both third-order and fourth-order methods. Copyright © 2021, The Authors. All rights reserved.

关键词： Finite element method

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An Ising Machine Formulation for Design Updates in Topology Optimization of Flow Channels

arXiv

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arXiv 2024年

作者： Suzuki, Yudai Aoki, Shiori Key, Fabian Endo, Katsuhiro Matsuda, Yoshiki Tanaka, Shu Behr, Marek Muramatsu, Mayu Quantum Computing Center Keio University Yokohama Kanagawa Japan Graduate School of Science and Technology Keio University Yokohama Kanagawa Japan Institute of Lightweight Design and Structural Biomechanics TU Wien Austria Tsukuba Ibaraki Japan Fixstars Corporation Tokyo Japan Green Computing System Research Organization Waseda University Tokyo Japan Department of Applied Physics and Physico-Informatics Keio University Yokohama Kanagawa Japan Keio University Tokyo Japan Keio University Tokyo Japan Computational Analysis of Technical Systems RWTH Aachen University Germany Department of Mechanical Engineering Keio University Yokohama Kanagawa Japan

Topology optimization is an essential tool in computational engineering, for example, to improve the design and efficiency of flow channels. At the same time, Ising machines, including digital or quantum annealers, have been used as efficient solvers for combinatorial optimization problems. Beyond combinatorial optimization, recent works have demonstrated applicability to other engineering tasks by tailoring corresponding problem formulations. In this study, we present a novel Ising machine formulation for computing design updates during topology optimization with the goal of minimizing dissipation energy in flow channels. We explore the potential of this approach to improve the efficiency and performance of the optimization process. To this end, we conduct experiments to study the impact of various factors within the novel formulation. Additionally, we compare it to a classical method using the number of optimization steps and the final values of the objective function as indicators of the time intensity of the optimization and the performance of the resulting designs, respectively. Our findings show that the proposed update strategy can accelerate the topology optimization process while producing comparable designs. However, it tends to be less exploratory, which may lead to lower performance of the designs. These results highlight the potential of incorporating Ising formulations for optimization tasks but also show their limitations when used to compute design updates in an iterative optimization process. In conclusion, this work provides an efficient alternative for design updates in topology optimization and enhances the understanding of integrating Ising machine formulations in engineering optimization. © 2024, CC BY-NC-ND.

关键词： Shape optimization

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HOMOGENIZATION FOR POLYNOMIAL OPTIMIZATION WITH UNBOUNDED SETS

arXiv

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arXiv 2021年

作者： Huang, Lei Nie, Jiawang Yuan, Ya-Xiang Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences Beijing100190 China Department of Mathematics University of California 9500 Gilman Drive La Jolla San DiegoCA92093 United States Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China

This paper considers polynomial optimization with unbounded sets. We give a homogenization formulation and propose a hierarchy of Moment-SOS relaxations to solve it. Under the assumptions that the feasible set is closed at infinity and the ideal of homogenized equality constraining polynomials is real radical, we show that this hierarchy of Moment-SOS relaxations has finite convergence, if some optimality conditions (i.e., the linear independence constraint qualification, strict complementarity and second order sufficient conditions) hold at every minimizer, including the one at infinity. Moreover, we prove extended versions of Putinar-Vasilescu type Positivstellensatz for polynomials that are nonnegative on unbounded sets. The classical Moment-SOS hierarchy with denominators is also studied. In particular, we give a positive answer to a conjecture of Mai, Lasserre and Magron in their recent work. Polynomial optimization and Homogenization and Moment-SOS relaxations and Optimality conditions. Copyright © 2021, The Authors. All rights reserved.

关键词： Polynomials

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Stochastic Three-Operator Splitting Algorithms for Nonconvex and Nonsmooth Optimization Arising from FLASH Radiotherapy

arXiv

引用

arXiv 2023年

作者： Bian, Fengmiao Liu, Jiulong Zhang, Xiaoqun Gao, Hao Cai, Jian-Feng Department of Mathematics The Hong Kong University of Science and Technology Hong Kong Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China School of Mathematical Sciences MOE-LSC Institute of Natural Sciences Shanghai Jiao Tong University Shanghai China Department of Radiation Oncology University of Kansas Medical Center Kansas CityKS United States HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute Futian Shenzhen China

Radiation therapy (RT) aims to deliver tumoricidal doses with minimal radiation-induced normal-tissue toxicity. Compared to conventional RT (of conventional dose rate), FLASH-RT (of ultra-high dose rate) can provide additional normal tissue sparing, which however has created a new nonconvex and nonsmooth optimization problem that is highly challenging to solve. In this paper, we propose a stochastic three-operator splitting (STOS) algorithm to address the FLASH optimization problem. We establish the convergence and convergence rates of the STOS algorithm under the nonconvex framework for both unbiased gradient estimators and variance-reduced gradient estimators. These stochastic gradient estimators include the most popular ones, such as SGD, SAGA, SARAH, and SVRG, among others. The effectiveness of the STOS algorithm is validated using FLASH radiotherapy planning for patients. Copyright © 2023, The Authors. All rights reserved.

关键词： Radiotherapy

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Non-thermal Magnetic Deicing Using Two-Dimensional Chromium Telluride

arXiv

引用

arXiv 2024年

作者： Gowda, Chinmayee Chowde Kartsev, Alexey Tiwari, Nishant Safronov, A.A. Pandey, Prafull Roy, Ajit K. Ajayan, Pulickel M. Galvão, Douglas S. Tiwary, Chandra Sekhar School of Nano Science and Technology Indian Institute of Technology West Bengal Kharagpur721302 India Computing Center of the Far Eastern Branch The Russian Academy of Sciences Khabarovsk680000 Russia MIREA-Russian Technological University Moscow119454 Russia 6 Miklukho-Maklaya St Moscow117198 Russia Department of Metallurgical and Materials Engineering Indian Institute of Technology West Bengal Kharagpur721302 India Materials Engineering Indian Institute of Technology Gandhinagar Gujurat 382055 India Materials and Manufacturing Directorate Air Force Research Laboratory Wright Patterson AFBOH45433-7718 United States Department of Materials Science and NanoEngineering Rice University 6100 S Main Street HoustonTX77005 United States Applied Physics Department and Computational Engineering and Sciences State University of Campinas SP Campinas13083-970 Brazil

Two-dimensional (2D) chromium telluride Cr2Te3 exhibits strong ferromagnetic ordering with high coercivity at low temperatures and paramagnetic behavior when approaching room temperature. The spin states of monolayer Cr2Te3 shows ferromagnetic ordering in the ground state, and in-situ Raman analysis shows reversible structure transformation and hence ferromagnetic to paramagnetic transition during low-temperature heating cycles (0 - 25 °C). The magnetic phase transition near room temperature in the 2D Cr2Te3 prompted the study of these layered material exploration for energy application. We demonstrate that the low-temperature ferromagnetic behavior can be used to magnetically deice material surfaces using an external magnetic source, avoiding the use of harsh chemicals and high temperatures. The hydrophobic nature and dipole interactions of H2O molecules with the surface of the 2D Cr2Te3 coating aid in the condensation of ice droplets formed on the surface. First-principles calculations also confirm the observed crystal structure, surface interaction, and magnetic properties of 2D Cr2Te3 © 2024, CC BY.

关键词： Density functional theory

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Covariance-Based Joint Device Activity and Delay Detection in Asynchronous mMTC

arXiv

引用

arXiv 2021年

作者： Wang, Zhaorui Liu, Ya-Feng Liu, Liang The Department of Information Engineering The Chinese University of Hong Kong Hong Kong The State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China The Department of Electronic and Information Engineering The Hong Kong Polytechnic University Hong Kong

In this letter, we study the joint device activity and delay detection problem in asynchronous massive machine-type communications (mMTC), where all active devices asynchronously transmit their preassigned preamble sequences to the base station (BS) for device identification and delay detection. We first formulate this joint detection problem as a maximum likelihood estimation problem, which depends on the received signal only through its sample covariance, and then propose efficient coordinate descent type of algorithms to solve the formulated problem. Our proposed covariance-based approach is sharply different from the existing compressed sensing (CS) approach for the same problem. Numerical results show that our proposed covariance-based approach significantly outperforms the CS approach in terms of the detection performance since our proposed approach can make better use of the BS antennas than the CS approach. © 2021, CC BY.

关键词： Compressed sensing

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Enhancing the fidelity of social media image data sets in earthquake damage assessment

引用

Earthquake Spectra 2025年

作者： Huang, Huili Zhang, Danrong Masalava, Anastasiya Roozbahani, Max Mahdi Roy, Nimisha Frost, J David School of Computational Science and Engineering Georgia Institute of Technology AtlantaGA United States School of Computer Science Georgia Institute of Technology AtlantaGA United States School of Computing Instruction Georgia Institute of Technology AtlantaGA United States School of Civil and Environmental Engineering Georgia Institute of Technology AtlantaGA United States

The development of artificial intelligence (AI) provides an opportunity for rapid and accurate assessment of earthquake-induced infrastructure damage using social media images. Nevertheless, data collection and labeling remain challenging due to limited expertise among annotators. This study introduces a novel four-class Earthquake Infrastructure Damage (EID) assessment data set compiled from a combination of images from several other social media image databases but with added emphasis on data quality. Unlike the previous data sets such as Damage Assessment Dataset (DAD) and Crisis Benchmark, the EID includes comprehensive labeling guidelines and a multiclass classification system aligned with established damage scales, such as HAZUS and EMS-98, to enhance the accuracy and utility of social media imagery for disaster response. By integrating detailed descriptions and clear labeling criteria, the labeling approach of EID reduces the subjective nature of image labeling and the inconsistencies found in existing data sets. The findings demonstrate a significant improvement in annotator agreement, reducing disagreement from 39.7% to 10.4%, thereby validating the efficacy of the refined labeling strategy. The EID, containing 13,513 high-quality images from five significant earthquakes, is designed to support community-level assessments and advanced computational research, paving the way for enhanced disaster response strategies through improved data utilization and analysis. The data set is available at DesignSafe: https://***/10.17603/ds2-yj8p-hs62. © The Author(s) 2025.

关键词： Tweets

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Data-driven derivation of partial differential equations using neural network model

引用

International Journal of Modeling, Simulation, and Scientific computing 2021年第2期12卷 1-19页

作者： Koji Koyamada Yu Long Graduate Takuma Kawamura Katsumi Konishi Academic Center for Computing and Media Studies Kyoto University Yoshida-honnmachi Sakyo-kuKyoto 606-8501Japan School of Engineering Kyoto University Yoshida-honnmachi Sakyo-kuKyoto 606-8501Japan Center for Computational Science and e-Systems Japan Atomic Energy Research Institute 148-4 Kashiwanoha Campus 178-4 WakashibaKashiwa-CityChiba 277-0871Japan Faculty of Computer and Information Sciences Hosei University 3-7-2Tajino-cho Koganei-shiTokyo 184-8584Japan

It has become critical to develop explanatory models using partial differential equations(PDEs)for big data from interesting scientific phenomena,e.g.,fluids,atmosphere,and cosmic *** data are often measured at discrete spatiotemporal *** this paper,we assume a PDE and consider a set of the PDE solution data at multiple discrete points as pseudo-measurement *** a data-driven PDE derivation,it is assumed that the PDE is a linear regression model comprising partial temporal and spatial differential terms,where the coefficients are estimated using regression analysis techniques,and the PDE derivation accuracy is defined as the difference(i.e.,error)between the exact and estimated coefficients.A spatiotemporal model is required to calculate the partial temporal and spatial differential terms;thus,we employ a spatiotemporal model based on a neural network(NN)obtained from big *** develop the data-driven PDE derivation technique,we employ PDEs with exact solutions such that we can calculate the differential terms by differentiating them analytically at multiple discrete *** we assume an activation function in the NN model,the partial differential term can be derived using a chain *** NN model accuracy is measured by the loss function and error between the exact and estimated partial differential *** addition,we clarify a requirement for an NN structure that can maximize the PDE derivation and NN model accuracy by varying the NN meta-parameters,i.e.,the numbers of NN layers and neurons.

关键词： Neural network partial differential equation regression analysis

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