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A Reduced-order Extrapolation Model Based on Proper Orthogonal Decomposition Technique for Rayleigh-Bénard convection

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Journal of Physics: Conference Series 2019年第2期1176卷

作者： Jinghua Yang Dengfeng Lu Zhiguang Deng Xiang Guan Qing Shi Sichuan Electric Power Design & Consulting Co. Ltd Chengdu Sichuan 610041 China National Key Labortory of Science and Technology on Reactor System Design Technology Sichuan 610213 China

In order to quickly calculate the flow characteristics in the simulated two-dimensional Rayleigh-Bénard convection model, a reduced-order extrapolation difference model for solving two-dimensional Rayleigh-Bénard is established based on the Proper Orthogonal Decomposition (POD) method. Firstly, the classical difference format is used to calculate the flow field on the initial time span, the sample data is to construct the POD basis, and the truncation error generated in the process of constructing the POD base is analysed. Then, the two-dimensional reduced-order extrapolation Rayleigh-Bénard model is constructed by combining the SVD and POD methods. By numerical examples, the classical difference model and the reduced-order extrapolation model are numerically simulated under the given initial boundary value. The reliability and effective of the reduced-order method are verified by comparing the flow field temperature cloud maps in the two calculation stages.

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PBDW method for state estimation: Error analysis for noisy data and nonlinear formulation

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arXiv 2019年

作者： Gong, Helin Maday, Yvon Mula, Olga Taddei, Tommaso Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Paris75005 France Institut Universitaire de France Paris75005 France Université Paris-Dauphine PSL Research University CNRS UMR 7534 CEREMADE Paris75016 France IMB UMR 5251 Univ. Bordeaux Talence33400 France Inria Bordeaux Sud-Ouest Team MEMPHIS Talence33400 France

We present an error analysis and further numerical investigations of the Parameterized-Background Data-Weak (PBDW) formulation to variational Data Assimilation (state estimation), proposed in [Y Maday, AT Patera, JD Penn, M Yano, Int J Numer Meth Eng, 102(5), 933-965]. The PBDW algorithm is a state estimation method involving reduced models. It aims at approximating an unknown function utrueliving in a highdimensional Hilbert space from M measurement observations given in the form ym= m(utrue), m = 1, ⋯, M, where mare linear functionals. The method approximates utruewith u = z + η. The background Z belongs to an N-dimensional linear space ZNbuilt from reduced modelling of a parameterized mathematical model, and the update η belongs to the space UMspanned by the Riesz representers of (1, ⋯, M). When the measurements are noisy - i.e., ym= m(utrue) + ϵmwith ϵmbeing a noise term - the classical PBDW formulation is not robust in the sense that, if N increases, the reconstruction accuracy degrades. In this paper, we propose to address this issue with an extension of the classical formulation, which consists in searching for the background z either on the whole ZNin the noise-free case, or on a well-chosen subset KN⊂ ZNin presence of noise. The restriction to KNmakes the reconstruction be nonlinear and is the key to make the algorithm significantly more robust against noise. We further present an a priori error and stability analysis, and we illustrate the efficiency of the approach on several numerical examples. Copyright © 2019, The Authors. All rights reserved.

关键词： Parameterization

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Front Cover: Direct Catalytic Conversion of Carbon Dioxide to Liquid Hydrocarbons over Cobalt Catalyst Supported on Lanthanum(III) Ion-Doped Cerium(IV) Oxide (ChemCatChem 17/2024)

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ChemCatChem 2024年第17期16卷

作者： Dr. Keigo Tashiro Hikaru Konno Akihide Yanagita Shunta Mikami Prof. Shuhei Shimoda Erika Taira Dr. David S. Rivera Rocabado Prof. Ken-ichi Shimizu Prof. Takayoshi Ishimoto Shigeo Satokawa Graduate School of Science and Technology Seikei University 3-3-1 Kichijoji-Kitamachi Musashino-shi Tokyo 180-8633 Japan College of Engineering Academic Institute Shizuoka University 3-5-1 Johoku Chuo-ku Hamamatsu-shi Shizuoka 432-8561 Japan Graduate School of Advance Science and Engineering Hiroshima University 1-4-1 Kagamiyama Higashi-Hiroshima Hiroshima 739-8527 Japan Institute for Catalysis Hokkaido University Kita 21 Nishi 10 Kita-ku Sapporo 001-0021 Japan Applicative Solution Lab Division JASCO Corporation 2967-5 Ishikawa-machi Hachioji-shi Tokyo 192-8537 Japan Center for Energy System Design (CESD) International Institute for Carbon-Neutral Energy Research (WPI−I2CNER) Kyushu University 744 Motooka Nishi Fukuoka 819-0395 Japan

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Nanoscale 3D printing of glass photonic crystals with near-unity reflectance in the visible spectrum

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science advances 2025年第21期11卷 eadv0267页

作者： Wang Zhang Hongtao Wang Hao Wang Son Tung Ha Lei Chen Xue Liang Li Cheng-Feng Pan Bochang Wu Md Abdur Rahman Yujie Ke Qifeng Ruan Xiaolong Yang Thomas Christensen Joel K W Yang Engineering Product Development Singapore University of Technology and Design Singapore 487372 Singapore. Singapore-HUJ Alliance for Research and Enterprise (SHARE) The Smart Grippers for Soft Robotics (SGSR) Programme Campus for Research Excellence and Technological Enterprise (CREATE) Singapore 138602 Singapore. School of Instrumentation and Optoelectronic Engineering Beihang University Beijing 100191 China. Hangzhou International Innovation Institute Beihang University Hangzhou 311115 China. Institute of Materials Research and Engineering (IMRE) Agency for Science Technology and Research (A*STAR) 2 Fusionopolis Way Innovis #08-03 Singapore 138634 Singapore. College of Mechanical and Vehicle Engineering Hunan University Changsha 410082 China. Department of Electrical and Computer Engineering National University of Singapore (NUS) 4 Engineering Drive 3 Singapore 117576 Singapore. School of Interdisciplinary Studies Lingnan University Tuen Mun Hong Kong SAR China. Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System Harbin Institute of Technology (Shenzhen) Shenzhen 518055 China. College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China. Department of Electrical and Photonics Engineering Technical University of Denmark Kongens Lyngby 2800 Denmark. POLIMA-Center for Polariton-driven Light-Matter Interactions University of Southern Denmark Campusvej 55 DK-5230 Odense M Denmark.

Glass is widely used as an optical material due to its high transparency, thermal stability, and mechanical properties. The ability to fabricate and sculpt glass at the nanoscale would naturally expand its application domain in nanophotonics. Here, we report an approach to print glass in three dimensions with nanoscale resolutions. We developed Glass-Nano, an organic-inorganic hybrid resin containing silicon elements. Using this high-resolution resin, three-dimensional (3D) photonic crystals (PhCs) were printed with two-photon lithography. After printing, the structures were heated to high temperatures in air to remove organic components and convert the remaining material into silica glass. 3D glass PhCs with periodicities as small as 260 nanometers were obtained after sintering at 650°C. The 3D glass PhCs exhibit ~100% reflectance in the visible range, surpassing the typical reflectances observed from similar structures in low-refractive index materials. The quality of PhCs achieved is observed in both electron microscopy and the excellent agreement with band structure calculations of idealized structures.

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Meso-macro scale model for dynamic fracture of functional graded material 14

Meso-macro scale model for dynamic fracture of functional gr...

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14th International Conference on Fracture, ICF 2017

作者： Bai, Xiaoming Shi, Kaikai Guo, Licheng Zheng, Liangang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Astronautic Science and Mechanics Harbin Institute of Technology Harbin150001 China

A meso-macro scale model for dynamic fracture of functional graded material is proposed in present work. The dynamic piecewise-exponential (DPE) model is extended to the meso-macro scale by the data mining method. With present model, the influence of meso-scale design parameters on macro-scale fracture behaviors can be investigated conveniently. Thus, the material design procedures and the fracture analysis of FGM are connected. © 2017 ICF 2017 - 14th International Conference on Fracture. All rights reserved.

关键词： Fracture

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The investigateion of damage and fracture behavior of particle reinforced composites at mesoscale under complex impact loads 14

The investigateion of damage and fracture behavior of partic...

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14th International Conference on Fracture, ICF 2017

作者： Bai, Xiaoming Guo, Licheng Shi, Kaikai Zheng, Liangang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Astronautic Science and Mechanics Harbin Institute of Technology Harbin150001 China

A mesoscale numerical model for the damage and fracture behavior of particle reinforced composites is proposed in present work. In this model, the digital image technique is used to reconstruct the real microstructure of composite material. The damping boundary condition is applied to absorb the artificial reflected stress wave during the simulation. Thus, the damage and fracture behavior of particle reinforced material under complex impact loads can be investigated. © 2017 ICF 2017 - 14th International Conference on Fracture. All rights reserved.

关键词： Particle reinforced composites

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Calculation strategy for the determination of plasticity correction factors 13th

Calculation strategy for the determination of plasticity cor...

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13th Asia-Pacific Symposium on Engineering Plasticity and its Applications, AEPA 2016

作者： Du, Juan Shao, Xue Jiao Kan, Qian Hua Zhang, Ying Fu, Xiao Long Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Southwest Jiaotong University Chengdu610031 China

ISBN: (纸本)9783035710243

This paper presents an investigation about the plasticity correction factor, Ke, proposed in the RCC-M code, for the correction of elastic stress range exceeds twice the yield stress which results from both mechanical and thermal loading. The plasticity correction factors are analyzed using a calculation strategy based on the comparison between linear elastic and elastoplastic analyses. The RCC-M code provides the codified expressions of Ke and material parameters for general materials of components in nuclear power plant, but there are no expressions and material parameters for new materials. Several elastoplastic models, geometries and loading types are considered in this study based on the general materials listed in RCC-M code to determine the calculation strategy of Ke for new material. Based on the results, the expressions and parameters of Ke for titanium alloy are discussed. It turns the proposed Ke factor of titanium alloy can yield to sufficiently conservative results. A verification calculation of general materials is performed and the conservative allowance is obtained. © 2017 Trans Tech Publications, Switzerland.

关键词： Plasticity

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A High Efficiency and Precision Interpolation Method for searching Fluid Field Information around Droplets in Sparse Two-phase Flow 17

A High Efficiency and Precision Interpolation Method for sea...

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Zhao, Fulong A. Bo, Hanliang B. Zhou, Ya C. Liu, Ying D. Institute of Nuclear and New Energy Technology Tsinghua University Beijing100084 China Science and Technology on Reactor System Design Technology Laboratory Nuclear PowerInstitute of China Chengdu610041 China

In the nuclear power station, the steam-water separator is a crucial appliance, a sequence of droplet lifecycle phenomena take place, including the droplet formation, droplet motion in the steam space, the mutual collisions between droplets, droplet extinction and the phase transformation. Together with the entraining steam, the droplets experiencing above complex processes consist a typical sparse two-phase flow, which can be well investigated by the Euler-Lagrange approach in terms of numerical simulations. With the Euler-Lagrange method, the microscopic behavior of the droplets and the steam-water separating mechanism are promising to be captured. When applying the Euler-Lagrange approach to simulate the droplets motion in the fluid field, one should first obtain the fluid parameters surrounding the droplets by the interpolation method, which may significantly influence the efficiency and precision of subsequent simulation results. In the present work, we examined the performance of four different interpolation schemes in the simulation of the droplet-steam flow inside the steam-water separator, including the k-d tree and the brute force search algorithm, the nearest point and 4-point interpolation method, and the boundary layer meshes refinement and total mesh refinement method. The computational efficiency and precision of the four methods were studied in comparison. The nearest point interpolation scheme takes less computing time, whereas with lower accuracy. Therefore, the sufficiently fine meshes are necessary to improve the calculation accuracy, which in turn lead to the reduced computational efficiency. The accuracy of the four-points interpolation scheme is remarkably higher than that of the nearest point interpolation scheme at the cost of much more (more than 2 folds) CPU time. To make a trade-off between the efficiency and precision, a high efficiency and precision interpolation method is put forward by combining the nearest point interpolation scheme

关键词： Mesh generation

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Numerical investigations of free surface vortices at hydraulic bottom intakes 17

Numerical investigations of free surface vortices at hydraul...

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Shi-wen, Liu Jie, Zhou Wei, Huang Xiang, Cheng Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China 328# Section 1 Changshun Road ShuangliuChengdu610041 China

To study the development mechanisms and flow structure characteristics of the free surface vortices and get a better understanding of the vortices phenomena. Two-phase, three dimensions, transient CFD simulations of free surface vortices at hydraulic bottom intakes have been conducted by using a volume-of-fluid (VOF) method and the scale-adaptive simulation turbulence model with curvature correction (SAS-CC). The flow field distribution and structure in different stages of transient free surface vortices were presented and analyzed. It was found that the movement and development of the vortex was determined by the interactions of main flow transportation, the axial stretching and radial dissipation of vortex. In addition, the flow characteristics on different flow conditions also have been studied, the results showed that a relatively large flow rate and small export size lead to stronger vortex, and increasing the fluid viscosity would to some extent reduce the vortex. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Vortex flow

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Research on heat removal capability of secondary passive residual heat removal system for small modular reactor 17

Research on heat removal capability of secondary passive res...

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Zhang, Dan Ran, Xu Zhou, Ke Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Xiehe Community ShuangLiu County Changshun Road No.328 Chengdu China

The transient performance of the Secondary Passive Residual Heat Removal system (SPRHR) for a small modular PWR was studied, the study focused on the thermal hydraulic characteristics at different initial water inventory in natural circulation loop of SPRHR. The result shows that, for SPRHR of SMR, after the short term of reactor scram, the small water inventory could maintain the two phase heat transfer state in the secondary side of Once-Through Steam Generator and the first side of emergency condenser, which will strengthen the heat transfer in SPRHR. However, for long time’s operation such as 72h, the water make up to the SPRHR should be considered as defense in depth for potential water leakage from system in accident situation. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Hydraulics

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