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第三届全国计算原子与分子物理学术会议

作者： Song Bin Zhang Jian Guo Wang R.K Janev Xiang Jun Chen Department of Modern Physics University of Science and Technology of China Hefei 230026 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Macedonian Academy of Sciences and Arts P. O. Box 428 1000 Skopje Macedonia

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Butterfly-Accelerated Solution of Coupled Volume Integral and Hydrodynamic Equations

Butterfly-Accelerated Solution of Coupled Volume Integral an...

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USNC-URSI Radio Science Meeting (Joint with AP-S Symposium)

作者： Doolos Aibek Uulu Yang Liu Abdulkadir C. Yucel Hakan Bagci Department of Mathematics and Natural Sciences University of Central Asia (UCA) Naryn Kyrgyzstan Applied Mathematics & Computational Research Division Lawrence Berkeley National Laboratory Berkeley USA School of Electrical and Electronic Engineering Nanyang Technological University (NTU) Singapore Computer Electrical and Mathematical Science and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal Saudi Arabia

ISBN: (数字)9789463968119

ISBN: (纸本)9798350359497

In recent years, advancements in plasmonic devices have enabled the localization of electromagnetic fields at subwavelength scales, contributing to breakthroughs in various scientific and engineering fields (J. C. Ndukaife, et al., ACS Nano, 2014,8,9,9035-9043). These structures are often made of metals and their electric properties are typically represented by the classical Drude model (S. A. Maier, 2007, Springer, New York). As the size of the plasmonic structures approaches the nanoscale, the classical Drude model falls short in explaining the collective movement of free electrons in metals. The interaction between moving charges and the electromagnetic fields can be described by a coupled system of the Maxwell and hydrodynamic equations (X. Zheng, et al., IEEE Trans. Antennas Propag., 2018,66,9, 4759-4771).

关键词： Location awareness Conferences Integral equations Metals Plasmons Hydrodynamics Mathematical models

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PROOFS OF MODULO 11 AND 13 CYLINDRIC KANADE-RUSSELL CONJECTURES FOR A2 ROGERS-RAMANUJAN TYPE IDENTITIES

arXiv

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arXiv 2023年

作者： Uncu, Ali Kemal Johann Radon Institute for Computational and Applied Mathematics Austrian Academy of Science Altenbergerstraße 69 LinzA-4040 Austria University of Bath Faculty of Science Department of Computer Science BathBA2 7AY United Kingdom

We present proofs of two new families of sum-product identities arising from the cylindric parti tions paradigm. Most of the presented expressions, the related sum-product identities, and the ingredients for the proofs were first conjectured by Kanade-Russell in the spirit of Andrews-Schilling-Warnaar identities o the A2 Rogers-Ramanujan type. We follow the footsteps of Kanade-Russell while we alter the computations heavily to accomplish our *** Codes 05A15, 05A17, 05A19, 11B65, 11P84, 17B65, 68R05 Copyright © 2023, The Authors. All rights reserved.

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On the relationship between forecast accuracy and detection performance: An application to biosurveillance

On the relationship between forecast accuracy and detection ...

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IEEE Conference on Technologies for Homeland Security

作者： Thomas Lotze Galit Shmueli Applied Mathematics and Scientific Computation Program University of Maryland College Park MD USA Department of Decision Operations & Information Technologies and Center for Health and Information Decision Systems University of Maryland College Park MD USA

While many methods have been proposed for detecting disease outbreaks from pre-diagnostic data, their performance is usually not well understood. In this paper, we describe the relationship between forecast accuracy and the detection accuracy of a method. We argue that most existing temporal detection methods for biosurveillance can be characterized as a forecasting component coupled with a monitoring/detection component. We show that improved forecasting results in improved detection and we quantify the relationship between forecast accuracy and detection metrics under different scenarios. The forecast accuracy can then be used to rate an algorithm's expected performance in detecting outbreaks. Simulation is used to compare empirical performance with theoretical results; we also show examples with authentic biosurveillance data.

关键词： Control charts Yttrium Educational institutions Diseases Signal generators Bioinformatics Probability Condition monitoring Error correction Statistics

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A parallel approach to digital holographic reconstruction with twin-image removal

A parallel approach to digital holographic reconstruction wi...

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IEEE Southeastcon

作者： Chihyung Tu J. Gerlach Sung-Chi Chu Ting-Chung Poon Computational Sciences Program Radford University Radford VA USA Department of Mathematics Radford University Radford VA USA Department of Computer Science Radford University Radford VA USA Bradley Department of Electrical Engineering Virginia Polytechnic Institute and State University Blacksburg VA USA

A parallel method developed for reconstructing images from holograms obtained with optical scanning holography is presented. A standard portable message-passing library, MPI or message-passing interface, is used to provide the environment of parallel programming. The parallel method is implemented using a network of workstations. The process of reconstructing images with twin-image removal from holograms is performed in parallel with respect to different reconstruction planes of interest. This process contributes to possible faster three-dimensional object identification to be investigated in future research.

关键词： Holography Image reconstruction Holographic optical components Optical recording Convolution Optical filters Concurrent computing Parallel processing Master-slave mathematics

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Network geometry and market instability

arXiv

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arXiv 2020年

作者： Samal, Areejit Pharasi, Hirdesh Kumar Ramaia, Sarath Jyotsna Kannan, Harish Saucan, Emil Jost, Jürgen Chakraborti, Anirban Chennai600113 India Instituto de Ciencias Físicas Universidad Nacional Autónoma de México Cuernavaca62210 Mexico Department of Applied Mathematics and Computational Sciences PSG College of Technology Coimbatore641004 India Department of Mathematics University of California San Diego San diegoCA92093 United States Department of Applied Mathematics ORT Braude College Karmiel2161002 Israel Max Planck Institute for Mathematics in the Sciences Leipzig04103 Germany The Santa Fe Institute Santa FeNM87501 United States School of Computational and Integrative Sciences Jawaharlal Nehru University New Delhi110067 India Jindal School of Government and Public Policy O.P. Jindal Global University Sonipat131001 India Centro Internacional de Ciencias Cuernavaca62210 Mexico

The complexity of financial markets arise from the strategic interactions among agents trading stocks, which manifest in the form of vibrant correlation patterns among stock prices. Over the past few decades, complex financial markets have often been represented as networks whose interacting pairs of nodes are stocks, connected by edges that signify the correlation strengths. However, we often have interactions that occur in groups of three or more nodes, and these cannot be described simply by pairwise interactions but we also need to take the relations between these interactions into account. Only recently, researchers have started devoting attention to the higher-order architecture of complex financial systems, that can significantly enhance our ability to estimate systemic risk as well as measure the robustness of financial systems in terms of market efficiency. Geometry-inspired network measures, such as the Ollivier-Ricci curvature and Forman-Ricci curvature, can be used to capture the network fragility and continuously monitor financial dynamics. Here, we explore the utility of such discrete Ricci curvatures in characterizing the structure of financial systems, and further, evaluate them as generic indicators of the market instability. For this purpose, we examine the daily returns from a set of stocks comprising the USA S&P-500 and the Japanese Nikkei-225 over a 32-year period, and monitor the changes in the edge-centric network curvatures. We find that the different geometric measures capture well the system-level features of the market and hence we can distinguish between the normal or ‘business-as-usual’ periods and all the major market crashes. This can be very useful in strategic designing of financial systems and regulating the markets in order to tackle financial instabilities. Copyright © 2020, The Authors. All rights reserved.

关键词： Financial markets

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Not all spacetime coordinates for general-relativistic ray tracing are created equal

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Physical Review D 2023年第8期108卷 084004-084004页

作者： Gabriele Bozzola Chi-kwan Chan Vasileios Paschalidis Department of Astronomy University of Arizona Tucson Arizona USA Data Science Institute University of Arizona Tucson Arizona USA and Program in Applied Mathematics University of Arizona Tucson Arizona USA Department of Astronomy University of Arizona Tucson Arizona USA and Department of Physics University of Arizona Tucson Arizona USA

Models for the observational appearance of astrophysical black holes rely critically on accurate general-relativistic ray tracing and radiation transport to compute the intensity measured by a distant observer. In this paper, we illustrate how the choice of coordinates and initial conditions affect this process. In particular, we show that propagating rays from the camera to the source leads to different solutions if the spatial part of the momentum of the photon points towards the horizon or away from it. In doing this, we also show that coordinates that are well suited for numerical general-relativistic magnetohydrodynamic (GRMHD) simulations are typically not optimal for generic ray tracing. We discuss the implications for black hole images and show that radiation transport in optimal and nonoptimal spacetime coordinates lead to the same images up to numerical errors and algorithmic choices.

关键词： Classical black holes General relativity Accretion disk & black-hole plasma Astronomical black holes Numerical techniques Relativistic magnetohydrodynamics

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A Likelihood Approach to Nonparametric Estimation of a Singular Distribution Using Deep Generative Models

arXiv

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arXiv 2021年

作者： Chae, Minwoo Kim, Dongha Kim, Yongdai Lin, Lizhen Department of Industrial and Management Engineering Pohang University of Science and Technology Gyeongbuk Pohang37673 Korea Republic of School of Mathematics Statistics and Data Science Data Science Center Sungshin Women’s University Seoul02844 Korea Republic of Department of Statistics Seoul National University Seoul08826 Korea Republic of Department of Applied and Computational Mathematics and Statistics University of Notre Dame South BendIN46556 United States

We investigate statistical properties of a likelihood approach to nonparametric estimation of a singular distribution using deep generative models. More specifically, a deep generative model is used to model high-dimensional data that are assumed to concentrate around some low-dimensional structure. Estimating the distribution supported on this low-dimensional structure, such as a low-dimensional manifold, is challenging due to its singularity with respect to the Lebesgue measure in the ambient space. In the considered model, a usual likelihood approach can fail to estimate the target distribution consistently due to the singularity. We prove that a novel and effective solution exists by perturbing the data with an instance noise, which leads to consistent estimation of the underlying distribution with desirable convergence rates. We also characterize the class of distributions that can be efficiently estimated via deep generative models. This class is sufficiently general to contain various structured distributions such as product distributions, classically smooth distributions and distributions supported on a low-dimensional manifold. Our analysis provides some insights on how deep generative models can avoid the curse of dimensionality for nonparametric distribution estimation. We conduct a thorough simulation study and real data analysis to empirically demonstrate that the proposed data perturbation technique improves the estimation performance *** Codes 62G05 (Primary), 62G20 (Secondary) © 2021, CC BY-NC-SA.

关键词： Perturbation techniques

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An adaptive moving mesh discontinuous Galerkin method for the radiative transfer equation

arXiv

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arXiv 2018年

作者： Zhang, Min Cheng, Juan Huang, Weizhang Qiu, Jianxian School of Mathematical Sciences Xiamen University XiamenFujian361005 China Institute of Applied Physics and Computational Mathematics Beijing100094 China Department of Mathematics University of Kansas LawrenceKS66045 United States School of Mathematical Sciences Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific Computing Xiamen University XiamenFujian361005 China

The radiative transfer equation models the interaction of radiation with scattering and absorbing media and has important applications in various fields in science and engineering. It is an integro-differential equation involving time, space and angular variables and contains an integral term in angular directions while being hyperbolic in space. The challenges for its numerical solution include the needs to handle with its high dimensionality, the presence of the integral term, and the development of discontinuities and sharp layers in its solution along spatial directions. Its numerical solution is studied in this paper using an adaptive moving mesh discontinuous Galerkin method for spatial discretization together with the discrete ordinate method for angular discretization. The former employs a dynamic mesh adaptation strategy based on moving mesh partial differential equations to improve computational accuracy and efficiency. Its mesh adaptation ability, accuracy, and efficiency are demonstrated in a selection of one- and two-dimensional numerical *** Codes 65M50, 65M60, 65M70, 65R05, 65.75 Copyright © 2018, The Authors. All rights reserved.

关键词： Radiative transfer

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Nonlinear Geometric Effects in Mechanical Bistable Morphing Structures

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Physical Review Letters 2012年第11期109卷 114302-114302页

作者： Zi Chen Qiaohang Guo Carmel Majidi Wenzhe Chen David J. Srolovitz Mikko P. Haataja Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials (PRISM) Princeton University Princeton New Jersey 08544 USA Department of Biomedical Engineering Washington University St. Louis Missouri 63130 USA College of Materials Science and Engineering Fuzhou University Fuzhou Fujian 350108 China Department of Mathematics and Physics Fujian University of Technology Fuzhou Fujian 350108 China Department of Mechanical Engineering Carnegie Mellon University Pittsburgh Pennsylvania 15213 USA Department of Materials Science and Engineering Fujian University of Technology Fuzhou Fujian 350108 China Institute for High Performance Computing 1 Fusionopolis Way Singapore 138632 Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA School of Mathematics Institute for Advanced Study Princeton New Jersey 08540 USA

Bistable structures associated with nonlinear deformation behavior, exemplified by the Venus flytrap and slap bracelet, can switch between different functional shapes upon actuation. Despite numerous efforts in modeling such large deformation behavior of shells, the roles of mechanical and nonlinear geometric effects on bistability remain elusive. We demonstrate, through both theoretical analysis and tabletop experiments, that two dimensionless parameters control bistability. Our work classifies the conditions for bistability, and extends the large deformation theory of plates and shells.

关键词： NONLINEAR theories DEFORMATIONS (Mechanics) PARAMETER estimation OPTICAL bistability STRUCTURAL shells PLATES (Engineering) CRYSTAL structure

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