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Numerical solutions of 2-D steady compressible natural convection using high-order flux reconstruction

Acta Mechanica Sinica 2019年第2期35卷 401-410页

作者： yaojie yu Feng Liu Tingbo Zhou Chao gao ya Liu National Key Laboratory of Aerodynamic Design and Research Northwestern Polytechnical UniversityXi’an 710072 China Department of Mechanical and Aerospace Engineering University of California Irvine Irvine CA 92697 USA Facility Design and Instrumentation Institute China Aerodynamics Research and Development CenterMianyang 621000 China

Low Mach number flows are common and typical in industrial applications. When simulating these flows, performance of traditional compressible flow solvers can deteriorate in terms of both efficiency and accuracy. In this paper, a new high-order numerical method for two-dimensional(2-D)state low Mach number flows is proposed by combining flux reconstruction(FR)and preconditioning. Firstly, a Couette flow problem is used to assess the efficiency and accuracy of preconditioned FR. It is found that the FR scheme with preconditioning is much more efficient than the original FR scheme. Meanwhile,this improvement still preserves the numerical accuracy. Using this new method and without the Boussinesq assumption,classic natural convection is directly simulated for cases of small and large temperature differences. For the small temperature difference, a p and h refinement study is conducted to verify the grid convergence and accuracy. Then, the influence of the Rayleigh number (Ra) is analyzed. By comparing with the reference results, the numerical results of preconditioned FR is very close to that calculated by incompressible solvers. Furthermore, a large temperature difference test case is calculated and analyzed, indicating this method is not limited by the Boussinesq assumption and is also applicable to heat convection with large temperature differences.

关键词： Flux reconstruction Preconditioning method Low Mach flows Natural convection

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空位缺陷硅烯纳米带结构与自旋极化电子性质的密度泛函紧束缚研究

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原子与分子物理学报 2025年第3期42卷 61-66页

作者：扶锦云吴丽君王爽迟中钰刘亚沈阳理工大学理学院沈阳110159

随着纳米电子器件和自旋电子学的不断发展,对小尺寸的纳米硅材料物理和化学性质的研究是研发新型微电子材料器件的基础.硅烯纳米带在实验制备和理论研究中均备受关注.本研究利用基于自洽电荷的密度泛函理论紧束缚方法,研究了不同宽度的... 详细信息

随着纳米电子器件和自旋电子学的不断发展,对小尺寸的纳米硅材料物理和化学性质的研究是研发新型微电子材料器件的基础.硅烯纳米带在实验制备和理论研究中均备受关注.本研究利用基于自洽电荷的密度泛函理论紧束缚方法,研究了不同宽度的硅烯纳米带的结构、稳定性和自旋极化电子性质.研究发现,稳定的完美和带有空位缺陷的硅烯纳米带表现为带有曲翘褶皱的蜂窝结构.纳米带边缘的曲翘度大于中心位置.空位缺陷更容易出现在纳米带边缘.纳米带的宽度可实现完美的硅烯纳米带的半导体性质和金属性之间的转换.硅烯纳米带中出现空位缺陷可有效调控纳米带自旋电子性质从半导体向金属性转变、半导体向半金属性转变,及金属性向为半导体或者半金属性质的转变.这种自旋电子性质的调控手段使得该种纳米材料在纳米电子自旋器件上有着潜在的应用价值.

关键词：硅烯纳米带自旋极化电子性质密度泛函紧束缚空位缺陷

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Preparation and characterization of a novel hybrid chelating material for effective adsorption of Cu(Ⅱ)and Pb(Ⅱ)

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Journal of Environmental Sciences 2018年第5期30卷 224-236页

作者： ya Liu Peng Qian ya.g yu Bo yu Yongliang Wang Shufeng Ye yunfa Chen State Key Laboratory of Multiphase Complex Systems institute of Process EngineeringChinese Academy of SciencesBeijing 100190China Lakehead University Thunder BayON PTB 5E1Canada University of Chinese Academy of Sciences Beijing 100049China

The discharge of heavy metal ions such as Cu^2＋and Pb^2＋poses a severe threat to public health and the environment owing to their extreme toxicity and bioaccumulation through food chains Herein, we report a novel organic–inorganic hybrid adsorbent, Al（OH）3-poly（acrylamide dimethyldiallylammonium chloride）-graft-dithiocarbamate（APD）, for rapid and effectiv removal of Cu^2＋and Pb^2＋. In this adsorbent, the ＂star-like＂ structure of Al（OH）3 poly（acrylamide-dimethyldiallylammonium chloride） served as the support of dithiocarbamat（DTC） functional groups for easy access of heavy metal ions and assisted development of larg and compact floccules. The synthesized adsorbent was characterized by scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FTIR）, and thermogravimetric analysis（TgA）. APD was demonstrated to hav rapid adsorption kinetics with an initial rate of 267.379 and 2569.373 mg/（g·min） as well a superior adsorption capacities of 317.777 and 586.699 mg/g for Cu2＋and Pb2＋respectively. Th adsorption process was spontaneous and endothermic, involving intraparticle diffusion and chemical interaction between heavy metal ions and the functional groups of APD. To assess it versatility and wide applicability, APD was also used in turbid heavy metal wastewater, and performed well in removing suspended particles and heavy metal ions simultaneously through flocculation and chelation. The rapid, convenient and effective adsorption of Cu^2＋and Pb^2＋give APD great potential for heavy metal decontamination in industrial applications.

关键词： Hybrid polymer Dithiocarbamate Heavy metal ions Adsorption

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Mechanical properties of defective L1_(2)-Al_(3)X(X=Sc,Lu)phase:A first-principles study

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Journal of Rare Earths 2021年第2期39卷 217-224页

作者： yu Wang ya'nan Meng Junsheng Wang Chi Zhang Houbing Huang School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China

The mechanical properties of Al_(3)X(X=Sc,Lu)were studied by density functional theory(DFT).The elastic constants and formation enthalpy indicate that the L1_(2)-Al_(3)X(X=Sc and Lu)are mechanically and thermodynamically *** bulk moduli and shear moduli show that Al_(3)Sc has better resistance to volume and shape changes than AI3 ***,the calculated results show that Al_(3)Lu has better plasticity than Al_(3)*** properties of structural stability and elastic moduli of the crystal containing four major types of point defects in L1_(2)-Al_(3)X(X=Sc and Lu)were *** mechanical properties of point defects show that point defects cause L1_(2)-Al_(3)X lattice distortion and change the corresponding elastic *** defects reduce the Young’s,shear and bulk moduli but have little effects on the crystal brittleness and toughness of Al_(3)Sc and Al_(3)***,we have found that Lu addition into aluminum alloys is a very good replacement for expensive Sc addition when the L1_(2)structures are desired for nucleation or strengthening precipitates in aluminum alloys.

关键词： Density functional theory First-principle L1_(2)-Al_(3)X Mechanical property Defects Rare earths

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Microstructural evolution and mechanical properties of 55NiCrMoV7 hot-work die steel during quenching and tempering treatments

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Advances in Manufacturing 2021年第4期9卷 520-537页

作者： Xing-Sheng yu Chuan Wu Ru-Xing Shi ya-Sha yuan Luoya.g CITIC HIC Casting&Forging Co. LtdLuoyang 471039HenanPeople’s Republic of China National-Local Joint Engineering Laboratory of Intelligent Manufacturing Oriented Automobile Die&Mould Tianjin University of Technology and EducationTianjin 300222People’s Republic of China CITIC Heavy Industries Co. LtdLuoyang 471039HenanPeople’s Republic of China

55NiCrMoV7 hot-work die steel is mainly used to manufacture heavy forgings in the fields of aerospace and *** study aims to clarify the effects of heat treatment on the microstructural evolution and mechanical properties of the steel,in order to find out an optimal heat treatment scheme to obtain an excellent balance of strength,ductility and *** steel was quenched at temperature from 790℃ to 910℃ followed by tempering treatments of 100–650℃ for 5 *** mechanical property tests were carried out by tensile,impact toughness and *** microscope(OM),scanning electron microscope(SEM)and transmission electron microscope(TEM)were used to observe the austenite grains,lath martensite,carbides and fracture *** results show that the quenching temperature mainly influences the austenite grain size and the volume fraction of undissolved carbides(UCs),while the tempering temperature mainly influences the size and morphology of the martensite with a body centered cubic(BCC)and the carbides with a face centered cubic(FCC).The mechanical properties of the steel,including yield and tensile strength,ductility,impact toughness and hardness,get an excellent balance at a quenching range of 850–870*** the tempering temperature increases,the yield and tensile strength and hardness decrease,while the ductility and impact toughness *** variation trends can be further verified by fracture SEM observation and *** with a macro-micro coupled finite element(MMFE)modeling technique,the cooling rate,microstructural evolution and yield strength of the steel were predicted and compared with the tested data.

关键词： Hot-work die steel Microstructural evolution Mechanical properties Heat treatment Macro-micro coupled modeling and simulation

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Photon-phonon squeezing and entanglement in a cavity optomechanical system with a flying atom

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Frontiers of physics 2019年第1期14卷 93-98页

作者： Jun-Hao Liu yu-Bao Zhang ya-Fei yu Zhi-Ming Zhang guangdong Provincial Key Laboratory of Nanophotonic Functional Materials & Devices (SIPSE) and Guangdong Provincial Key Laboratory of Quantum Engineering & Quantum Materials South China Normal University Guangzhou 510006 China Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials & Devices (SIPSE) and Guangdong Provincial Key Laboratory of Quantum Engineering & Quantum Materials South China Normal University Guangzhou 510006 China

We study the quadrature squeezing and entanglement in a cavity optomechanical system (COMS). In our model, a flying atom sequentially passes through and interacts with the COMS and a Ramsey pulse zone, and subsequently the atomic state is detected. In this way, the photon-phonon squeezing and entanglement can be generated. The dynamic evolution of the squeezing and entanglement in the presence of losses are examined by using the master equation method.

关键词： optomechanics squeezing entanglement

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Nutraceutical support for respiratory diseases

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Food Science and Human Wellness 2018年第3期7卷 205-208页

作者： yu-ya Hwang yuan-Soon Ho graduate Institute of Medical Sciences College of MedicineTaipei Medical UniversityTaipei 10031TaiwanChina

Respiratory diseases have been a major health concern for human beings since several *** the irritated nasal passages and airways had been a mutual necessity in multiple ancient *** ancient China,herbs were largely used to help deal with cough and reduce mucus,thereby maintaining respiratory *** India,knowledge of herb-related remedies passed down through *** the human society,freshly prepared herb ointments,including air-dried herbs,and boiled herbal soups have had a long history of combining botanical nutrients with local *** the use of herbs and natural products from plants(NPFPs)has been primarily cited in reviews based on modern respiratory diseases,the concept of soothing and alleviating disease progression or reducing mucus production has been highly ***,only a few herbs could directly disrupt the irreversible fibrotic *** the other hand,natural products from animals(NPFAs)have more potential in disrupting procollagen or extracellular matrix *** to these reasons,NPFAs could be considered as important functional foods for patients with respiratory *** this article,we provide a review of both NPFAs and NPFPs that are adjuvant to respiratory health.

关键词： Respiratory disease NPFP NPFA Nutrition Antioxidants

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Sodium iron hexacyanoferrate with high Na content as a Na-rich cathode material for Na-ion batteries

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Nano Research 2015年第1期8卷 117-128页

作者： ya You Xiqian yu yaxia Yin Kyung-Wan Nam yu-guo guo CAS Key Laboratory of Molecular Nanostructure and Nanotechnology and Beijing National Laboratory for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences (CAS) Beijing 100190 Chino Chemistry Department Brookhaven National Laboratory Upton New York 11973 USA Department of Energy and Materials Engineering Dongguk University Seoul 100-715 Republic of Korea

Owing to the worldwide abundance and low-cost of Na, room-temperature Na-ion batteries are emerging as attractive energy storage systems for large- scale grids. Increasing the Na content in cathode materials is one of the effective ways to achieve high energy density. Prussian blue and its analogues （PBAs） are promising Na-rich cathode materials since they can theoretically store two Na＋ ions per formula unit. However, increasing the Na content in PBAs cathode materials remains a major challenge. Here we show that sodium iron hexacyanoferrate with high Na content can be obtained by simply controlling the reducing agent and reaction atmosphere during synthesis. The Na content can reach as high as 1.63 per formula, which is the highest value for sodium iron hexacyanoferrate. This Na-rich sodium iron hexacyanoferrate demonstrates a high specific capacity of 150 mAh·g^-1 and remarkable cycling performance with 90% capacity retention after 200 cycles. Furthermore, the Na intercalation/ de-intercalation mechanism has been systematically studied by in situ Raman spectroscopy, X-ray diffraction and X-ray absorption spectroscopy analysis for the first time. The Na-rich sodium iron hexacyanoferrate can function as a plenteous Na reservoir and has great potential as a cathode material for practical Na-ion batteries.

关键词： sodium iron hexacyanoferrate Na-rich cathode sodium-ion batteries Prussian blue analogues

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In-situ SEM characterization of fracture mechanism of TiB/Ti-2Al-6Sn titanium matrix composites after electroshocking treatment

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Rare Metals 2024年第6期43卷 2805-2818页

作者： ya-ya Wu Jian Zhou guo-lei Han yan Wen Zhou Wang Li-Qiang Wang Wei-Jie Lv le-Chun Xie Lin Hua Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan 430070China Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing 100124China State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

In this article,in-situ scanning electron microscope characterization of the tensile properties of TiB/Ti-2Al-6Sn titanium matrix composite(TMC)was conducted before and after electroshocking treatment(EST).After EST,the tensile strength increased by 113.2 *** effect of EST on the tensile strength and fracture behavior of TiB was investigated using in-situ characterization of the fracture morphology and crack propagation path of the matrix and *** EST,TiB fracture introduced cracks that extended into the matrix,resulting in material *** EST,the refined TiB improved the bearing capacity of the matrix,thereby improving TMC ***,after EST,the cracks were introduced into the matrix,and resulting the fracture of matrix *** an increase in the external load,cracks in the matrix were observed to propagate to TiB,and the refined TiB was fractured,detached,and pulled out,resulting in the formation of *** the propagation path of the main crack after EST showed that the deflection angle of the main crack *** micro structure of the fracture surface indicated that the fracture of the matrix was plastic,whereas that of TiB was *** EST,the size and area of the dimples increased,confirming the increase in *** results revealed that the comprehensive mechanical properties of TiB/Ti-2Al-6Sn improved after ***,EST is an efficient method for tailoring the micro structures and mechanical properties of TMCs.

关键词： TiB/Ti-2Al-6Sn In-situ microstructure characterization Tensile properties Reinforcement Electroshocking treatment(EST)

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Understanding the structural evolution and Na^＋ kinetics in honeycomb-ordered O＇3-Na3Ni2SbO6 cathodes

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Nano Research 2018年第6期11卷 3258-3271页

作者： Peng-Fei Wang Hu-Rong yao ya You Yong-gang Sun ya-Xia Yin yu-guo guo Chinese Academy of Science (CAS) Key Laboratory of Molecular Nanostructure and Nanotechnology Beijing National Laboratory for Molecular Science CAS Research/Education Center for Excellence in Molecular Sciences Institute of Chemistry Chinese Academy o Sciences Beijing 100190 China School of Chemistry and Chemical Engineering University of Chinese Academy of Sciences Beijing 100049 China

The development of new sodium ion battery （SIB） cathodes with satisfactory performance requires an in-depth understanding of their structure-function relationships, to rationally design better electrode materials. In this work highly ordered, honeycomb-layered Na3Ni2SbO6 was prepared to elucidate the structural evolution and Na~ kinetics during electrochemical desodiation/sodiation processes. Structural analysis involving in situ synchrotron X-ray diffraction （XRD） experiments, electrochemical performance measurements, and electrochemical characterization （galvanostatic intermittent titration technique, gITT） methods were used to obtain new insights into the reaction mechanism controlling the （de）intercalation of sodium into the host NaB-xNi2SbO6 structure. Two phase transitions occur （initial O＇3 phase → intermediate P＇3 phase→final O1 phase） upon Na^＋ extraction; the partial irreversible O＇3-P＇3 phase transition is responsible for the insufficient cycling stability. The fast Na^＋ mobility （average 10^-12 cm^2·s^-1） in the interlayer, high equilibrium voltage （3.27 V）, and low voltage polarization （50 mV） establish the linkage between kinetic advantage and a good rate performance of the cathode. These new findings provide deep insight into the reaction mechanism operating in the honeycomb cathode; the present approach could be also extended to investigate other materials for SIBs.

关键词： sodium-ion batteries (SIB) cathode honeycomb-ordered structural evolution Na^+ kinetics

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