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A mixed discontinuous galerkin method for linear elasticity with strongly imposed symmetry

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arXiv

arXiv 2019年

作者： Wang, Fei Wu, Shuonan Xu, Jinchao School of Mathematics and Statistics and State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi710049 China School of Mathematical Sciences Peking University Beijing100871 China Department of Mathematics Pennsylvania State University University ParkPA16802 United States

In this paper, we study a mixed discontinuous Galerkin (MDG) method to solve linear elasticity problem with arbitrary order discontinuous finite element spaces in d-dimension (d = 2, 3). This method uses polynomials of degree k + 1 for the stress and of degree k for the displacement (k > 0). The mixed DG scheme is proved to be well-posed under proper norms. Specifically, we prove that, for any k > 0, the H(div)-like error estimate for the stress and L2 error estimate for the displacement are optimal. We further establish the optimal L2 error estimate for the stress provided that the Pk+2 - P-1 k+1 Stokes pair is stable and k > d. We also provide numerical results of MDG showing that the orders of convergence are actually sharp.65N30, 65M60 Copyright © 2019, The Authors. All rights reserved.

关键词： Galerkin methods

Zif-8 Loaded Ag/Zno Electrospun Nanofibers Enabling High-Performance H2 Gas Sensing for Battery Safety Early Warning

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SSRN 2024年

作者： Wang, Ze Zhu, Lei Zhang, Jiaxin Wang, Jingzhao Cui, Xiangming Chen, Xin Liu, Wenbiao Ma, Hang Wang, Jianan Yan, Wei Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University 28 Xianning West Road Xi’an710049 China School of Physics and Electrical Engineering Weinan Normal University Chaoyang Street Weinan714099 China Center of Research & Development Yunnan Yuntianhua Co. LTD 1417 Dianchi Road Kunming650228 China

Safety issues triggered by battery thermal runaway have become the most crucial obstacle to the future development of the high-energy-density energy storage systems. As hydrogen (H2) will be inevitably generated along with heat release caused by the side reactions in the early stages of battery thermal runaway, rapid monitoring of trace H2 is considered as an effective measure enabling the battery safety early warning. Herein, to develop high-performance H2 sensing materials to monitor of low-concentration H2 leakage, ZIF-8 loaded Ag/ZnO electrospun nanofibers (ZAZ NFs) were designed by electrospinning and self-sacrificial template methods. Benefiting from all the enrichment and sieving effects of ZIF-8 shell, the catalytic and sensitization effects of Ag and abundant active sites provided by Ag and ZIF-8 loading, the ZAZ sensor enables ppb-level limit of detection toward H2, fast response (9 s), high selectivity and excellent humidity resistance (36.1 to 100 ppm H2 at 95% RH). Furthermore, this ZAZ sensor also enabled the safety early warning (67.79 s before battery bulge) for practical pouch lithium cells, highlighting its great application potential in future advanced battery safety management system. © 2024, The Authors. All rights reserved.

关键词： Organometallics

Kinetic Characteristics of Passivation Behavior in OFP-Cu and OF-Cu

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SSRN 2024年

作者： Ning, Zhiyuan Wen, Du Zhou, Qulan Li, Na Macdonald, Digby D. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Departments of Nuclear Engineering and Materials Science and Engineering University of California at Berkeley BerkeleyCA94720 United States Industrial Process and Energy Systems Engineering Ećole Polytechnique Fédérale de Lausanne EPFL SionCH-1951 Switzerland

This research presents a comprehensive comparative analysis of the passivation kinetics of OFP-Cu and OF-Cu in simulated repository electrolyte. The study employs a range of techniques, including potentiodynamic polarization, multi-step potentiostatic polarization, electrochemical impedance spectroscopy, and Mott-Schottky analysis, to explore the intricacies of corrosion behavior. The Point Defect Model (PDM) is used to interpret the steady-state physicochemical processes. Utilizing the results of PDM optimization, defect distribution diagrams within the passivation film were constructed, shedding light on the pivotal transition from p-type to n-type semiconductor properties of the film. The study concludes with an interpretation of the experimental data, highlighting the enhancement of copper's corrosion resistance due to phosphorus doping, as elucidated by the Solute-Vacancy Interaction Model. © 2024, The Authors. All rights reserved.

关键词： Copper corrosion

Origin of Granular Capillarity Revealed by Particle-Based Simulations

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Physical Review Letters 2017年第21期118卷 218001-218001页

作者： Fengxian Fan Eric J. R. Parteli Thorsten Pöschel Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Jun Gong Road 516 200093 Shanghai China Institute for Multiscale Simulation Friedrich-Alexander-Universität Erlangen-Nürnberg Nägelsbachstraße 49b 91052 Erlangen Germany Department of Geosciences University of Cologne Pohligstraße 3 50969 Cologne Germany

When a thin tube is dipped into water, the water will ascend to a certain height, against the action of gravity. While this effect, termed capillarity, is well known, recent experiments have shown that agitated granular matter reveals a similar behavior. Namely, when a vertical tube is inserted into a container filled with granular material and is then set into vertical vibration, the particles rise up along the tube. In the present Letter, we investigate the effect of granular capillarity by means of numerical simulations and show that the effect is caused by convection of the granular material in the container. Moreover, we identify two regimes of behavior for the capillary height Hc∞ depending on the tube-to-particle-diameter ratio, D/d. For large D/d, a scaling of Hc∞ with the inverse of the tube diameter, which is reminiscent of liquids, is observed. However, when D/d decreases down to values smaller than a few particle sizes, a uniquely granular behavior is observed where Hc∞ increases linearly with the tube diameter.

关键词： Classical mechanics Complex systems Wetting Dry granular materials

Study on dryout point in vertical narrow annuli

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Nuclear Science and Techniques/Hewuli 2005年第1期000卷

作者： TIAN Wen-xi AYE Myint QIU Sui-zheng JIA Dou-nan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049

Prediction of dryout point is experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap respectively. The annulus with narrow gap is bilaterally heated by AC current power supply. The experimental conditions covered a range of pressure from 0.8 to 3.5 MPa, mass flux of 26.6 to 68.8 kg·m-2·s-1 and wall heat flux of 5 to 50 kW·m-2. The location of dryout is obtained by observing a sudden rise in surface temperature. Kutateladze correlation is cited and modified to predict the location of dryout and proved to be not a proper one. Considering in detail the effects of geometry of annuli, pressure, mass flux and heat flux on dryout, an empirical correction is finally developed to predict dryout point in narrow annular gap under low flow condition, which has a good agreement with experimental data.

关键词： Narrow annular channel Bilaterally heating Dryout point Critical quality Annular flow

Interlink between Abnormal Water Imbibition in Hydrophilic and Rapid flow in Hydrophobic Nanochannels

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Physical Review Letters 2024年第18期132卷 184001-184001页

作者： Runfeng Zhou Mehdi Neek-Amal Francois M. Peeters Bofeng Bai Chengzhen Sun State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China Department of Physics Shahid Rajaee Teacher Training University 16875-163 Lavizan Tehran Iran Departement Fysica Universiteit Antwerpen Groenenborgerlaan 171 B-2020 Antwerpen Belgium Departamento de Física Universidade Federal do Ceará Fortaleza-CE 60455-760 Brazil

Nanoscale extension and refinement of the Lucas-Washburn model is presented with a detailed analysis of recent experimental data and extensive molecular dynamics simulations to investigate rapid water flow and water imbibition within nanocapillaries. Through a comparative analysis of capillary rise in hydrophilic nanochannels, an unexpected reversal of the anticipated trend, with an abnormal peak, of imbibition length below the size of 3 nm was discovered in hydrophilic nanochannels, surprisingly sharing the same physical origin as the well-known peak observed in flow rate within hydrophobic nanochannels. The extended imbibition model is applicable across diverse spatiotemporal scales and validated against simulation results and existing experimental data for both hydrophilic and hydrophobic nanochannels.

关键词： Imbibition & injection Nanofluidics Molecular dynamics Navier-Stokes equation

Construction of a Transient Multi-Physics Model of Solid Oxide Fuel Cell Fed by Biomass Syngas Considering the Carbon Deposition and Temperature Effect

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SSRN 2022年

作者： Zhu, Pengfei Yao, Jing Wu, Zhen Huang, Si-Min Abu Mansor, Mohd Radzi Yang, Fusheng Zhang, Zaoxiao School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China Guangdong Provincial Key Laboratory of Distributed Energy Systems Guangdong Provincial Engineering Research Center of Distributed Energy Systems Dongguan University of Technology Dongguan523808 China Department of Mechanical and Manufacturing Engineering University Kebangsaan Malaysia Selangor43600 Malaysia State Key Laboratory of Multiphase Flow for Power Engineering Xi’an Jiaotong University Xi’an710049 China

Carbon deposition is a thorny issue for the SOFC fueled by low carbon hydrocarbons such as biomass syngas. Moreover, long-term large temperature gradients would reduce SOFC durability. Regarding these two issues, a two dimensional transient multi-physical model considering carbon deposition and temperature effect is developed for SOFC in this work. Typically due to the carbon deposition, the SOFC anode porosity decreases from 0.5 to 0.26, and the reaction activity decreases from 1.0 to about 0.45 after running 140 day. Accordingly, the current density decreases by 1.6 % at t =42 d and 6% at t =140 d, which indicates the damage of SOFC durability compared to the durability target (1%/1000h) of commercial SOFC. The maximum temperature difference of the cell is predicted to be about 106 o C. It was found that the carbon deposition and large temperature gradient are closely related to the operating parameters. With the increase of operating voltage from 0.4 V to 0.8 V, the porosity and reaction activity respectively increase by 50% and 55%, and the maximum temperature difference is reduced from 150 o C to 16 o C after running 140 day. The increase of the inlet temperature could improve the overall temperature and decrease the porosity. Besides, the reduction in the ratio of CH 4 to H 2 O helps to suppress carbon deposition, thus to improving the performance. © 2022, The Authors. All rights reserved.

关键词： Solid oxide fuel cells (SOFC)

Rationally Engineered Reox-Cuso4/Tio2 Catalyst with Superior Nh3-Sco Efficiency and Remarkably Boosted So2 Tolerance: Synergy of Acid Sites and Surface Adsorbed Oxygen

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SSRN 2022年

作者： Yu, Yanke Wei, Desheng Tong, Zhaojian Wang, Jinxiu Chen, Jinsheng He, Chi Department of Environmental Science and Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Center for Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences Xiamen361021 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China National Engineering Laboratory for VOCs Pollution Control Material & Technology University of Chinese Academy of Sciences Beijing101408 China

Ammonia (NH3) is a critical component causing environmental problems like haze and water pollution. Selective catalytic oxidation of ammonia (NH3-SCO) to N2 and H2O is a promising method to abate NH3 emission. However, inferior SO2 tolerance is still a tremendous challenge to be conquered for present NH3-SCO catalysts regarding practical applications. Application of materials which was difficult to be sulfated by SO2 should be an effective pathway to solve this problem. Here, a ReOx-CuSO4/TiO2 catalyst which coupled the advantages of ReOx (Rhenium oxides, supplying highly active adsorbed surface oxygen for enhancing NH3-SCO reaction) and CuSO4 (providing Brønsted acid sites for inhibiting the formation of N2O) was rationally fabricated. Results indicated that ReOx-CuSO4/TiO2 catalyst performed excellent catalytic performance in NH3-SCO with almost 100% of NH3 oxidized at 300 °C (N2 selectivity as high as 96%). Crucially, the composite catalyst exhibited incredible activity and stability under harsh reaction conditions toward SO2 (600 ppm) and H2O (4.0 vol.%) owing to the superior inhibition capability for SO2 adsorption. In situ DRIFTS, in situ Raman and in situ XPS demonstrated that the NH3-SCO reaction over ReOx-CuSO4/TiO2 catalyst mainly obeyed a N2H4 reaction mechanism and oxidation-reduction circle between Re7+ and Re6+ played a vital role. In addition, SO2 would not affect this reaction mechanism on ReOx-CuSO4/TiO2 catalyst. The knowledge and understanding reported could provide critical insights for the design and optimization of efficient materials for industrial NH3 oxidative elimination. © 2022, The Authors. All rights reserved.

关键词： Ammonia

Experimental Study on Fragmentation Characteristics of Molten Stainless Steel Discharged into Liquid Lbe Pool

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SSRN 2024年

作者： Fan, Shuowang Chen, Yutong Zhang, Dalin Deng, Jian Zhang, Xisi Wu, Xiaoli Tian, Wenxi Qiu, Suizheng Su, Guanghui School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China Shanghai Nuclear Engineering Research and Design Institute Co. Ltd 29 Hongcao Road Shanghai200233 China Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

The LFR is a candidate for the Generation-IV nuclear systems, where the process of MFCI differs from that occurred in LWRs and SFRs. In the absence of experimental study and widely applied theoretical models for LFRs, experiments on the interaction between molten SS and liquid LBE are conducted in this study under eight conditions. The morphological characteristics and fragment sizes of the products are analyzed based on the hydrodynamic effect parameter (We) and thermal effect parameter (Tic). Simplified thermal fragmentation models are established, where the innermost layer of the solidified shell is subjected to the maximum tangential compressive stress, while the outermost layer is subjected to the maximum tangential tensile stress. As the shell thickness increases, the total tangential stress of the outermost layer decreases. The fragmentation will occur when the maximum tangential stress on the shell exceeds the shell tensile strength. © 2024, The Authors. All rights reserved.

关键词： Tensile strength