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DoD High Performance Computing Modernization program Users Group

作者： A. Mahalov M. Moustaoui B. Nichols Program in Environmental Fluid Dynamics Department of Mechanical and Aerospace Engineering Department of Mathematics and Statistics Arizona State University Tempe AZ USA

Vertical nesting and adaptive vertical gridding in nested mesoscale weather research and forecasting (WRF)/microscale codes are developed. The inner nest of WRF is coupled with a sequence of embedded microscale nests, both horizontally and vertically. The fully three-dimensional (3D), compressible Navier-Stokes equations are solved with a stretched, adaptive grid in the vertical, with grid spacing down to a few meters in thin clear air turbulence (CAT) layers where strong turbulent mixing occurs. For nesting, both lateral and vertical boundary conditions are treated via relaxation zones where the velocity and temperature fields are relaxed to those obtained from the WRF inner nest. This methodology is applied to the analysis of field data from T-REX campaign of measurements. Real case simulations based on initial and boundary conditions from high resolution T799 L91 European centre for medium-range weather forecasts (ECMWF) analysis data are conducted. The embedded microscale nests predict localized shear layers and diagnose stiff gradients of vertical velocity and potential temperature above the tropopause and in the lower stratosphere. Three-dimensional instability mechanisms and turbulent dynamics within these CAT layers are fully resolved.

关键词： Weather forecasting Terrestrial atmosphere Boundary conditions Wind Stability Land surface temperature Data analysis Predictive models Adaptive optics Nonlinear optics

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Statistical inference for local granger causality

arXiv

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arXiv 2021年

作者： Liu, Yan Taniguchi, Masanobu Ombao, Hernando Institute for Mathematical Science Waseda University Institute for Science and Engineering Waseda University Statistics Program King Abdullah University of Science and Technology

Granger causality has been employed to investigate causality relations between components of stationary multiple time series. We generalize this concept by developing statistical inference for local Granger causality for multivariate locally stationary processes. Our proposed local Granger causality approach captures time-evolving causality relationships in nonstationary processes. The proposed local Granger causality is well represented in the frequency domain and estimated based on the parametric time-varying spectral density matrix using the local Whittle likelihood. Under regularity conditions, we demonstrate that the estimators converge to multivariate normal in distribution. Additionally, the test statistic for the local Granger causality is shown to be asymptotically distributed as a quadratic form of a multivariate normal distribution. The finite sample performance is confirmed with several simulation studies for multivariate time-varying autoregressive models. For practical demonstration, the proposed local Granger causality method uncovered new functional connectivity relationships between channels in brain signals. Moreover, the method was able to identify structural changes in financial *** Codes 62M10, 62M15 © 2021, CC BY.

关键词： Statistical tests

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Characterization of Stratospheric Clear Air Turbulence for Air Force Platforms

Characterization of Stratospheric Clear Air Turbulence for A...

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Users Group Conference

作者： Alex Mahalov Mohamed Moustaoui Basil Nichols Department of Mechanical and AeroSpace Engineering Department of Mathematics and StatisticsProgram in Environmental Fluid Dynamics Arizona State University Tempe AZ USA

Stratospheric mechanical turbulence (altitudes 12-25km) is characterized by patchy high frequency fluctuations in the stratospheric wind fields and long-lived energetic eddies with a few hundred meters scales in the vertical. The thin clear air turbulence (CAT) layers negatively impact the effective control, stability and performance of the newest generation of unmanned air vehicles (UAV) such as the Global Hawk. Flying through stratospheric CAT causes the autopilot to begin pitch oscillations that seriously degrade photographic and synthetic aperture radar performance as well as putting the platform itself at risk. While there is a need for a real-time forecast of these thin stratospheric CAT layers, these cannot be resolved by even the latest generation of weather research and forecasting (WRF) mesoscale meteorological codes. Some of the objectives of this challenge project are to influence the development of the next generation mesoscale numerical weather prediction codes for the lower stratosphere, by improving subgrid-scale parametrization of nonhomogeneous, anisotropic, non-Kolmogorov, patchy shear stratified stratospheric turbulence; and to enable forecasting of nonlinear, non-monochromatic inertia-gravity waves with large horizontal wavelengths (few hundred kilometers) which generate thin (few hundred meters) CAT layers

关键词： Weather forecasting Unmanned aerial vehicles Frequency Fluctuations Stability Wind energy generation Degradation Meteorology Terrestrial atmosphere Anisotropic magnetoresistance

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Online stochastic generators using Slepian bases for regional bivariate wind speed ensembles from ERA5

arXiv

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arXiv 2024年

作者： Song, Yan Khalid, Zubair Genton, Marc G. Statistics Program King Abdullah University of Science and Technology Saudi Arabia School of Science and Engineering Lahore University of Management Sciences Pakistan

Reanalysis data, such as ERA5, provide a comprehensive and detailed representation of the Earth’s system by assimilating observations into climate models. While crucial for climate research, they pose significant challenges in terms of generation, storage, and management. For 3-hourly bivariate wind speed ensembles from ERA5, which face these challenges, this paper proposes an online stochastic generator (OSG) applicable to any global region, offering fast stochastic approximations while storing only model parameters. A key innovation is the incorporation of the online updating, which allows data to sequentially enter the model in blocks of time and contribute to parameter updates. This approach reduces storage demands during modeling by eliminating the need to store and analyze the entire dataset, and enables near real-time emulations that complement the generation of reanalysis data. The Slepian concentration technique supports the efficiency of the proposed OSG by representing the data in a lower-dimensional space spanned by data-independent Slepian bases optimally concentrated within the specified region. We demonstrate the flexibility and efficiency of the OSG through two case studies requiring long and short blocks, specified for the Arabian-Peninsula region (ARP). For both cases, the OSG performs well across several statistical metrics and is comparable to the SG trained on the full dataset. Copyright © 2024, The Authors. All rights reserved.

关键词： Wind

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Efficient stochastic generators with spherical harmonic transformation for high-resolution global climate simulations from CESM2-LENS2

arXiv

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arXiv 2023年

Earth system models (ESMs) are fundamental for understanding Earth’s complex climate system. However, the computational demands and storage requirements of ESM simulations limit their utility. For the newly published CESM2-LENS2 data, which suffer from this issue, we propose a novel stochastic generator (SG) as a practical complement to the CESM2, capable of rapidly producing emulations closely mirroring training simulations. Our SG leverages the spherical harmonic transformation (SHT) to shift from spatial to spectral domains, enabling efficient low-rank approximations that significantly reduce computational and storage costs. By accounting for axial symmetry and retaining distinct ranks for land and ocean regions, our SG captures intricate non-stationary spatial dependencies. Additionally, a modified Tukey g-and-h (TGH) transformation accommodates non-Gaussianity in high-temporal-resolution data. We apply the proposed SG to generate emulations for surface temperature simulations from the CESM2-LENS2 data across various scales, marking the first attempt of reproducing daily data. These emulations are then meticulously validated against training simulations. This work offers a promising complementary pathway for efficient climate modeling and analysis while overcoming computational and storage limitations. Copyright © 2023, The Authors. All rights reserved.

关键词： Earth system models

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A Full Eulerian Fluid-Membrane Coupling Method with a Smoothed Volume-of-Fluid Approach

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Communications in Computational Physics 2012年第7期12卷 544-576页

作者： Satoshi Ii Xiaobo Gong Kazuyasu Sugiyama Jinbiao Wu Huaxiong Huang Shu Takagi Department of Mechanical Engineering The University of Tokyo7-3-1 Hongo Bunkyo-kuTokyo113-8656Japan Department of Engineering Mechanics NAOCEShanghai Jiaotong UniversityShanghai 200240China LMAM&School of Mathematical Sciences Peking UniversityBeijing 100871China Department of Mathematics and Statistics York University4700 Keele StreetTorontoOntarioCanada Computational Science Research Program RIKEN2-1 Hirosawa WakoSaitama351-0198Japan.

A novel full Eulerian fluid-elastic membrane coupling method on the fixed Cartesian coordinate mesh is proposed within the framework of the volume-of-fluid *** present method is based on a full Eulerian fluid-(bulk)structure coupling solver(Sugiyama et al.,***.,230(2011)596–627),with the bulk structure replaced by elastic *** this study,a closed membrane is considered,and it is described by a volume-of-fluid or volume-fraction information generally called VOF function.A smoothed indicator(or characteristic)function is introduced as a phase indicator which results in a smoothed VOF *** smoothed VOF function uses a smoothed delta function,and it enables a membrane singular force to be incorporated into a mixture momentum *** order to deal with a membrane deformation on the Eulerian mesh,a deformation tensor is introduced and updated within a compactly supported region near the *** the neo-Hookean and the Skalak models are employed in the numerical simulations.A smoothed(and less dissipative)interface capturing method is employed for the advection of the VOF function and the quantities defined on the *** stability restriction due to membrane stiffness is relaxed by using a quasi-implicit *** present method is validated by using the spherical membrane deformation problems,and is applied to a pressure-driven flow with the biconcave membrane capsules(red blood cells).

关键词： Fluid-membrane interaction Eulerian formulation Cartesian mesh volume-of-fluid quasi-implicit approach red blood cell

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A stochastic MPEC approach for grid tariff design with demand-side flexibility

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ENERGY SYSTEMS-OPTIMIZATION MODELING SIMULATION AND ECONOMIC ASPECTS 2023年第3期14卷 707-729页

作者： Askeland, Magnus Burandt, Thorsten Gabriel, Steven A. Energy Systems SINTEF Energy Research Trondheim Norway Department of Electric Power Engineering Norwegian University of Science and Technology Trondheim Norway Workgroup for Infrastructure Policy Technical University of Berlin Berlin Germany The Energy Transportation Environment Department German Institute for Economic Research (DIW Berlin) Berlin Germany Department of Industrial Economics and Technology Management Norwegian University of Science and Technology Trondheim Norway Department of Mechanical Engineering Applied Math and Statistics Scientific Computation Program University of Maryland College Park MD USA

As the end-users increasingly can provide flexibility to the power system, it is important to consider how this flexibility can be activated as a resource for the grid. Electricity network tariffs is one option that can be used to activate this flexibility. Therefore, by designing efficient grid tariffs, it might be possible to reduce the total costs in the power system by incentivizing a change in consumption patterns. This paper provides a methodology for optimal grid tariff design under decentralized decision-making and uncertainty in demand, power prices, and renewable generation. A bilevel model is formulated to adequately describe the interaction between the end-users and a distribution system operator. In addition, a centralized decision-making model is provided for benchmarking purposes. The bilevel model is reformulated as a mixed-integer linear problem solvable by branch-and-cut techniques. Results based on both deterministic and stochastic settings are presented and discussed. The findings suggest how electricity grid tariffs should be designed to provide an efficient price signal for reducing aggregate network peaks.

关键词： Bilevel problem Grid tariffs Mathematical program with equilibrium constraints (MPEC) Uncertainty

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Deflation technique to accelerate the convergence of iterative solver for the wave scattering problem

Deflation technique to accelerate the convergence of iterati...

引用

2019 World Congress on engineering and Computer Science, WCECS 2019

作者： Sheikh, A.H. Shaikh, A.G. Hisamuddin Faraz, Naeem Ali, Asif Department of Mathematics and Statistics QUEST Nawabshah67480 Pakistan Department of Mathematics Shah Abdul Latif University Khairpur66020 Pakistan Center of International Program Donghua University Shanghai China Department of Basic Science and Related Studies Mehran University of Engineering and Technology Jamshoro76062 Pakistan

ISBN: (纸本)9789881404879

An iterative solution method for the discrete high wavenumber Helmholtz equation is presented. The basic idea for solution, already presented in [1], is to develop a preconditioner which is based on a Helmholtz operator with a complex-valued shift for a Krylov subspace iterative method. The preconditioner which can be seen as a strongly damped wave equation in Fourier space, can be approximately inverted by a multigrid method. Extensive deflation and spectral analysis, as Krylov subspace methods depends upon eigenvalues, highlights in this paper. Findings in analysis are validated by numerical results. © Newswood *** right reserved.

关键词： Helmholtz equation

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Using Cluster Analysis and Dynamic programming for Demand Response Applied to Electricity Load in Residential Homes

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Journal of engineering for Sustainable Buildings and Cities 2020年第1期1卷 011006页

作者： Chanpiwat, Pattanun Gabriel, Steven A. Moglen, Rachel L. Siemann, Michael J. Department of Mechanical Engineering University of Maryland College Park 20742 MD United States Department of Mechanical Engineering and the Applied Mathematics Statistics and Scientific Computation Program University of Maryland College Park 20742 MD United States Department of Industrial Economics and Technology Management Norwegian University of Science and Technology Trondheim NO-7491 Norway Operations Research and Industrial Engineering The University of Texas at Austin Austin 78712 TX United States Resideo Technologies Austin 78702 TX United States

This paper develops means to analyze and cluster residential households into homogeneous groups based on the electricity load. Classifying customers by electricity load profiles is a top priority for retail electric providers (REPs), so they can plan and conduct demand response (DR) effectively. We present a practical method to identify the most DR-profitable customer groups as opposed to tailoring DR programs for each separate household, which may be computationally prohibitive. Electricity load data of 10,000 residential households from 2017 located in Texas was used. The study proposed the clustered load-profile method (CLPM) to classify residential customers based on their electricity load profiles in combination with a dynamic program for DR scheduling to optimize DR profits. The main conclusions are that the proposed approach has an average 2.3% profitability improvement over a business-as-usual heuristic. In addition, the proposed method on average is approximately 70 times faster than running the DR dynamic programming separately for each household. Thus, our method not only is an important application to provide computational business insights for REPs and other power market participants but also enhances resilience for power grid with an advanced DR scheduling tool. Copyright © 2020 by ASME.

关键词： cluster analysis customer classification demand response dynamic programming energy efficiency integrated systems occupant behavior optimization residential household

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The determinant of individual smoking consumption in Central Java province 5

The determinant of individual smoking consumption in Central...

引用

5th International Conference on Mathematics, Science and Education 2018, ICMSE 2018

作者： Subanti, S. Hakim, A.R. Sriwiyanto, H.S.J.N. Hakim, I.M. Department of Statistics Faculty of Mathematics and Natural Science Universitas Sebelas Maret Indonesia Graduate Program in Economics Faculty of Economics and Business Universitas Indonesia Indonesia Department of Economic Development Faculty of Economics and Business Universitas Sebelas Maret Indonesia Institute for Research and Social Services Universitas Sebelas Maret Indonesia Department of Industrial Engineering Faculty of Engineering Universitas Indonesia Indonesia

The paper aims to determine the socio-economic factors that significantly affect the individual smoking consumption and to make smoker profile in Central Java Province. This paper uses national economy social survey (Susenas) based on individual analytical units. The estimation technique with ordinary least squares regression. The findings of the paper is the factors that significantly influence the individual smoking consumption are cigarette prices, income, marriage status, urban-rural, education level, poor status, and living condition. This study suggests that to reduce cigarette consumption, the government needs to increase the price of cigarettes. In addition, the government needs to promote anti-smoking campaigns and smoking bans at work. © Published under licence by IOP Publishing Ltd.

关键词： Tobacco

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