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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

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Cobalt oxide and carbon modified hematite nanorod arrays for improved photoelectrochemical water splitting

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Chinese Chemical Letters 2017年第12期28卷 2207-2211页

作者： Miao Wang Meng Wang Yanming Fu Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an fiaotong UniversityXi'on 710049China

Given the proper band gap, low cost and good stability, hematite （α-Fe2O3） has been considered as a promising candidate for photoelectrochemical （PEC） water splitting, however suffers from the sluggish surface water oxidation reaction kinetics. In this study, a simple dip-coating process was used to modify the surface of α-Fe2O3 nanorod arrays with cobalt oxide （COOx） and carbon （C） for the improved PEC performance, with a photocurrent density at 1.6V （vs. reversible hydrogen electrode, RHE） increased from 0.10 mA/cm2 for the pristine α-Fe2O3 to 0.37 mA/cm2 for the CoOx/C modified α-Fe2O3 nanorods. As revealed by electrochemical analysis, thanks to the synergistic effect of CoOx and C, the PEC enhancement could be attributed to the enhanced charge transfer ability, decreased surface charge recombination, and accelerated water oxidation reaction kinetics. This study serves as a good example for improving PEC water splitting performance via a simple method.

关键词： Hematite nanorodsSurface modificationPhotoelectrochemical water splittingWater oxidationElectrochemical impedance spectroscopy

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Research on the Influence of Helical Strakes on Dynamic Response of Floating Wind Turbine Platform

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China Ocean engineering 2017年第2期31卷 131-140页

作者： DING Qin-wei LI Chun School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093 China

The stability of platform structure is the paramount guarantee of the safe operation of the offshore floating wind turbine. The NREL 5MW floating wind turbine is established based on the OC3-Hywind Spar Buoy platform with the supplement of helical strakes for the purpose to analyze the impact of helical strakes on the dynamic response of the floating wind turbine Spar platform. The dynamic response of floating wind turbine Spar platform under wind, wave and current loading from the impact of number, height and pitch ratio of the helical strakes is analysed by the radiation and diffraction theory, the finite element method and orthogonal design method. The result reveals that the helical strakes can effectively inhibit the dynamic response of the platform but enlarge the wave exciting force; the best parameter combination is two pieces of helical strakes with the height of 15%D （D is the diameter of the platform） and the pitch ratio of 5; the height of the helical strake and its pitch ratio have significant influence on pitch response.

关键词： floating wind turbine platform helical strakes orthogonal design

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A mixed discontinuous Galerkin method with symmetric stress for Brinkman problem based on the velocity-pseudostress formulation

arXiv

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arXiv 2019年

作者： Qian, Yanxia Wu, Shuonan Wang, Fei Wang, Fei School of Mathematics and Statistics Xi'An Jiaotong University Xi'an Shaanxi710049 China School of Mathematical Sciences Peking University Beijing100871 China School of Mathematics and Statistics State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an Shaanxi710049 China

The Brinkman equations can be regarded as a combination of the Stokes and Darcy equations which model transitions between the fast flow in channels (governed by Stokes equations) and the slow flow in porous media (governed by Darcy?fs law). The numerical challenge for this model is the designing of a numerical scheme which is stable for both the Stokes-dominated (high permeability) and the Darcy-dominated (low permeability) equations. In this paper, we solve the Brinkman model in n dimensions (n = 2, 3) by using the mixed discontinuous Galerkin (MDG) method, which meets this challenge. This MDG method is based on the pseudostress-velocity formulation and uses a discontinuous piecewise polynomial pair PSk+1-Pk(k ≥ 0), where the stress field is symmetric. The main unknowns are the pseudostress and the velocity, whereas the pressure is easily recovered through a simple postprocessing. A key step in the analysis is to establish the parameter-robust inf-sup stability through specific parameter-dependent norms at both continuous and discrete levels. Therefore, the stability results presented here are uniform with respect to the permeability. Thanks to the parameter-robust stability analysis, we obtain optimal error estimates for the stress in broken H(div)-norm and velocity in L2-norm. Furthermore, the optimal L2 error estimate for pseudostress is derived under certain conditions. Finally, numerical experiments are provided to support the theoretical results and to show the robustness, accuracy, and flexibility of the MDG method. Copyright © 2019, The Authors. All rights reserved.

关键词： Stability

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Exploration over combined impacts of modified piston bowl geometry and tert -butyl hydroquinone additive-included biodiesel/diesel blend on diesel engine behaviors

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Fuel 2022年 322卷

作者： Krupakaran Radhakrishnan Lawrence Zuohua Huang Xuan Phuong Nguyen Dhinesh Balasubramanian Vidyasagar Reddy Gangula Raghurami Reddy Doddipalli Van Vang Le Sachuthananthan Bharathy Anh Tuan Hoang Department of Mechanical Engineering Sree Vidyanikethan Engineering College Tirupati Andhra Pradesh India State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an 710049 China PATET Research Group Ho Chi Minh City University of Transport Ho Chi Minh City Viet Nam Department of Mechanical Engineering Mepco Schlenk Engineering College Sivakasi India Mechanical Engineering Faculty of Engineering Khon Kaen University Khon Kaen Thailand Center for Alternative Energy Research and Development Khon Kaen University Khon Kaen Thailand Institute of Maritime Ho Chi Minh City University of Transport Ho Chi Minh City Viet Nam Institute of Engineering HUTECH University Ho Chi Minh City Viet Nam

Nowadays, the use of biodiesel for diesel engines has been attracting researchers aiming to improve engine characteristics although the engine performance could be decreased while utilizing biodiesel. In this aspect, optimizing the piston bowl geometry is one of the useful approaches to enhance the efficiency of the biodiesel-powered diesel engine. In this study, the standard piston of an existing diesel engine was modified into two different combustion bowls, namely Symmetrical Stepped Curved-V (SSCV) and Symmetrical Spline-V (SSV), to evaluate the CI engine performance powered with mixtures of sesame-originated biodiesel, diesel fuel, and tert -butyl hydroquinone (TBHQ) additive through two-stage experiment. In the first phase, experiments were carried out on two modified piston bowls powered by diesel and S20 (20% sesame biodiesel + 80% diesel fuel). Resultantly, SSV piston revealed superior engine characteristics to SSCV piston and standard piston due to enhanced air–fuel mixing and more complete combustion of SSV piston-based engine. Indeed, SSV piston operation exhibited an 8.68% of increased brake thermal efficiency (BTE), 6.54% of curtailed brake-specific fuel consumption (BSFC), 4.76% of lowered carbon monoxide (CO), 4.84% of decreased unburnt hydrocarbon (HC), and 2.22% of lowered smoke opacity but with increased nitrogen oxide (NOx) by 14.14% in comparison to diesel. In the 2nd phase, to control the NOx emission effectively, a TBHQ additive was added to the S20 sample at different proportions (500 mg and 1000 mg) to analyze the test engine behaviors with modified piston shapes. As a result, S20 + 500 mg TBHQ at 100% load improved BTE by 5.79% and reduced BSFC by 4.36% in the case of SSV piston. Moreover, it curtailed emissions of CO, HC, NOx, and smoke opacity by 13.33%, 15.49%, 12.09%, and 9.44%, respectively, when equated with diesel. Overall, S20 + 500 mg TBHQ could be thought of as a possible alternative fuel on SSV piston as it resulted in superior p

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Fabrication of highly reliable joint based on Cu/Ni/Sn double-layer powder for high temperature application

Fabrication of highly reliable joint based on Cu/Ni/Sn doubl...

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作者： Xu, Hongyan Shen, Yaochun Hu, Yihua Li, Jianqiang Xu, Ju Beijing Engineering Laboratory of Electrical Drive System and Power Electronic Device Packaging Technology Micro-Nano Fabrication Technology Department Institute of Electronic Engineering Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China School of Electrical Engineering Electronics and Computer Science University of Liverpool Brownlow Hill LiverpoolL69 3GJ United Kingdom State Key Laboratory of Multiphase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China

A highly reliable three-dimensional network structure joint was fabricated based on Cu/Ni/Sn powder with double-layer coatings and transient liquid phase bonding (TLPB) technology for high temperature application. The Cu/Ni/Sn joint is characterized by Cu metal particles embedded in the matrix of (Cu,Ni)6Sn5/Ni3Sn4 intermetallic compounds (IMCs), with a low void ratio, and can be reflowed at low temperatures (6Sn5/ Ni3Sn4 IMCs, and the Cu/Ni/Sn joint had a lower void ratio and a higher shear strength than those of Cu/Sn. The mechanism of the Ni-coating layer inhibiting phase transformation was studied. The high reliable three-dimensional network structure joint based on Cu/Ni/Sn double-layer powder was fabricated for high temperature application. Copyright © International Microelectronics Assembly and Packaging Society

关键词： High temperature applications

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Fabrication of highly reliable jointbased on Cu@Ni@Sn double-layerpowderfor high temperature application

Fabrication of highly reliable jointbased on Cu@Ni@Sn double...

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作者： Xu, Hongyan Shen, Yaochun Hu, Yihua Li, Jianqiang Xu, Ju Beijing Engineering Laboratory of Electrical Drive System & Power Electronic Device Packaging Technology Micro-nano fabrication technology department Institute of Electronic Engineering Chinese Academy of Sciences Beijing 100190 China School of Electrical Engineering Electronics andComputer Science University of Liverpool LiverpoolL69 3GJ United Kingdom State Key Laboratory of Multiphase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China

A highly reliable three-dimensional networkstructure jointwas fabricatedbased on Cu@Ni@Sn core-shell powderand transient liquid phase bonding (TLPB) technologyfor high temperature application. Cu@Ni@Sn joint is characterized by Cu metal particles embedded in the matrix of (Cu,Ni)6Sn5/Ni3Sn4intermetallics (IMCs), low level of voiding is achieved, they can be reflowed at a low temperatures( © 2019 IMAPS-International Microelectronics and Packaging Society. All rights reserved.

关键词： High temperature applications

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Cover Feature: Hollow Carbon Sphere-Modified Graphitic Carbon Nitride for Efficient Photocatalytic H2Production (Chem. Eur. J. 68/2021)

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Chemistry – A European Journal 2021年第68期27卷

作者： Dr. Jinghua Li Dr. Lunqiao Xiong Dr. Bing Luo Prof. Dengwei Jing Dr. Jiamei Cao Prof. Junwang Tang International Research Center for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 P. R. China Department of Chemical Engineering University College London London WC1E 7JE UK School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an Shaanxi 710049 P. R. China

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Structure engineering of Graphitic Carbon Nitride for Efficient Photocatalytic Water Splitting

Structure Engineering of Graphitic Carbon Nitride for Effici...

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中国化学会第三届中国能源材料化学研讨会

作者：沈少华 International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University

Photocatalytic overall water splitting without using sacrificial agents is very appealing for converting solar energy into chemical ***,polymer photocatalysts with tunable molecular structures have emerged as promisin... 详细信息

关键词： Structure engineering of Graphitic Carbon Nitride for Efficient Photocatalytic Water Splitting

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Co2 Capture Performance and Energy Recovery in Pilot-Scale Thermal Electrochemical Co-Drive System

SSRN

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SSRN 2019年

作者： Ding, Wancheng Yu, Yunsong Zhang, Zaoxiao Wang, Geoff School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China School of Chemical Engineering The University of Queensland St LuciaQLD4072 Australia

关键词： Greenhouse gases

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