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Flow field simulation of the thin metal ribbon formed by twin-belt rapid solidification

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Journal of University of Science and Technology Beijing 2008年第2期15卷 155-160页

作者： Yan liu Jianxin Xie feng Guo cheng Zhou School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Liaoning Institute of Technology Jingzhou 121001 China

The flow field formed when an aluminum ribbon is produced by twin-belt rapid solidification is simulated with the solution algorithm （SOLA）-volume of fluid （VOF） method, and the influence of casting speed and cooling-belt velocity on the flow field is analyzed for a given ejection nozzle size. It has been found that the flow field can be filled well when the width of the ejection nozzle outlet is the same as that of the up slit of the cooling belt. When the ejection nozzle outlet is wider than the up slit of the cooling belt, the aluminum fluid can fill well if only the casting speed matches the cooling-belt velocity properly, otherwise under filling occurs in some areas in the cooling zone.

关键词： rapid solidification twin-belt method numerical simulation ribbon forming

The age of the halo as determined from halo field stars

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Research in Astronomy and Astrophysics 2016年第3期16卷 73-80页

作者： Jin-cheng Guo Chao liu Ji-feng liu Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences College of Astronomy and Space Sciences University of Chinese Academy of Sciences

The age of the Galactic halo is a critical parameter that can constrain the origin of the stellar halo. In general, the Galactic stellar halo is believed to be very old. However, different independent measurements and techniques based on various types of stars are required so that the age estimates of the Galactic halo are accurate, robust, and reliable. In this work, we provide a novel approach to determine the age of the halo with turn-off stars. We first carefully select 63 field halo turn-off stars from the literature. Then, we compare them with the GARSTEC model, which takes the process of atomic diffusion into account in the B - V vs. metallicity plane. Finally, we run Monte Carlo simulations to consider the uncertainty of the color index and obtain the age of 10.5 ± 1.5 Gyr. This result is in agreement with previous studies. Future works are needed to collect more turn-off samples with more accurate photometry to reduce the uncertainty of the age.

关键词： galaxies: halos -- Galaxy: evolution -- stars: kinematics and dynamics

Engineering atomic Rb-N configurations to tune radical pathways for highly selective photocatalytic H2O2 synthesis coupled with biomass valorization

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Journal of Energy Chemistry 2025年第1期100卷 215-225页

作者： Jiaye Li Shuang Pan Yihuang Chen Qiong liu College of Chemistry and Materials Engineering Wenzhou University Guangdong Provincial Key Laboratory of Chemical Measurement and Emergency Test Technology (China) Institute of Analysis Guangdong Academy of Sciences (China National Analytical CenterGuangzhou)

Photocatalytic oxygen reduction for hydrogen peroxide （H2O2） synthesis presents a green and costeffective production ***,achieving highly selective H2O2synthesis remains challenging,necessitating precise control over free radical reaction pathways and minimizing undesirable oxidative ***,we report for the visible light-driven simultaneous co-photocatalytic reduction of O2to H2O2and oxidation of biomass using the atomic rubidium-nitride modified carbon nitride（CNRb）.The optimized CNRb catalyst demonstrates a record photoreduction rate of 8.01 mM h-1for H2O2generation and photooxidation rate of 3.75 mM h-1for furfuryl alcohol to furoic acid,achieving a remarkable solar-to-chemical conversion （SCC） efficiency of up to 2.27%.Experimental characterizations and DFT calculation disclosed that the introducing atomic Rb–N configurations allows for the high-selective generation of superoxide radicals while suppressing hydroxyl free radical *** is because the Rb–N serves as the new alternative site to perceive a stronger connection position for O2adsorption and reinforce the capability to extract protons,thereby triggering a high selective redox product *** study holds great potential in precisely regulating reactive radical processes at the atomic level,thereby paving the way for efficient synthesis of H2O2coupled with biomass valorization.

关键词： Atomic economy Radical pathway regulation Rubidium atom coordination Biomass valorization

Interactions between gut microbiota and berberine,a necessary procedure to understand the mechanisms of berberine

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Journal of Pharmaceutical Analysis 2022年第4期12卷 541-555页

作者： Hao cheng Juan liu Yuzhu Tan Wuwen feng cheng Peng State Key Laboratory of Southwestern Chinese Medicine Resources School of PharmacyChengdu University of Traditional Chinese MedicineChengdu611137China

Berberine(BBR),an isoquinoline alkaloid,has been found in many plants,such as Coptis chinensis Franch and Phellodendron chinense *** BBR has a wide spectrum of pharmacological effects,its oral bioavailability is extremely *** recent years,gut microbiota has emerged as a cynosure to understand the mechanisms of action of herbal *** studies have demonstrated that due to its low bioavailability,BBR can interact with the gut microbiota,thereby exhibiting altered pharmacological ***,no systematic and comprehensive review has summarized these interactions and their corresponding influences on pharmacological ***,we describe the direct interactive relationships between BBR and gut microbiota,including regulation of gut microbiota composition and metabolism by BBR and metabolization of BBR by gut *** addition,the complex interactions between gut microbiota and BBR as well as the side effects and personalized use of BBR are ***,we provide our viewpoint on future research directions regarding BBR and gut *** review not only helps to explain the mechanisms underlying BBR activity but also provides support for the rational use of BBR in clinical practice.

关键词： Berberine Gut microbiota Oral bioavailability Traditional Chinese medicines Short chain fatty acids

Preparation and applications of calcium ferrite as a functional material:A review

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 292-310页

作者： Xiuli Han Bowen Duan Lei liu Shilong Fang Weiwei Wang College of Mining Engineering North China University of Science and TechnologyTangshan 063210China Collaborative Innovation Center of Green Development and Ecological Restoration of Mineral Resources of Hebei Province Tangshan 063210China Key Laboratory of Mining Development and Security Technology of Hebei Province Tangshan 063210China

Calcium ferrite(CF)is recognized as a potential green and efficient functional material because of its advantages of magnetism,electrochemistry,catalysis,and biocompatibility in the fields of materials chemistry,environmental engineering,and ***-fore,the obtained research results need to be systematically summarized,and new perspectives on CF and its composite materials need to be *** on the presented studies of CF and its composite materials,the types and structures of the crystal are *** addition,the current application technologies and theoretical mechanisms with various properties in different fields are ***,the various preparation methods of CF and its composite materials are elaborated in *** importantly,the advantages and disadvantages of the synthesis methods of CF and its composite materials are discussed,and the existing problems and emerging challenges in practical production are ***,the key future research directions of CF and its composite materials have been prospected from the potential application technologies to provide references for its synthesis and efficient utilization.

关键词： calcium ferrite mineral functional materials preparation application perspectives

Multi-layer multi-pass friction rolling additive manufacturing of Al alloy:Toward complex large-scale high-performance components

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 425-438页

作者： Haibin liu Run Hou chenghao Wu Ruishan Xie Shujun Chen College of Mechanical&Energy Engineering Beijing University of TechnologyBeijing 100124China Chongqing Research Institute of Beijing University of Technology Chongqing 401121China

At present,the emerging solid-phase friction-based additive manufacturing technology,including friction rolling additive man-ufacturing(FRAM),can only manufacture simple single-pass *** this study,multi-layer multi-pass FRAM-deposited alumin-um alloy samples were successfully prepared using a non-shoulder tool *** material flow behavior and microstructure of the over-lapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum *** results showed that a mechanical interlocking structure was formed between the adjacent layers and the adja-cent passes in the overlapped center *** friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone,which made the recrystallization degree in the left and right edge zones of the over-lapped zone the highest,followed by the overlapped center zone and the non-overlapped *** tensile strength of the overlapped zone exceeded 90%of that of the single-pass deposition *** is proved that although there are uneven grooves on the surface of the over-lapping area during multi-layer and multi-pass deposition,they can be filled by the flow of materials during the deposition of the next lay-er,thus ensuring the dense microstructure and excellent mechanical properties of the overlapping *** multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.

关键词： aluminum alloy additive manufacturing solid-state friction stir welding multi-layer multi-pass

A note on the ill-posedness of shear flow for the MHD boundary layer equations

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Science China Mathematics 2018年第11期61卷 2065-2078页

作者： cheng-Jie liu feng Xie Tong Yang Institute of Natural Sciences Shanghai Jiao Tong University School of Mathematical Sciences and Key Laboratory of Scientific and Engineering Computing(Ministry of Education) Shanghai Jiao Tong University Department of Mathematics City University of Hong Kong

For the two-dimensional Magnetohydrodynamics(MHD)boundary layer system,it has been shown that the non-degenerate tangential magnetic field leads to the well-posedness in Sobolev spaces and high Reynolds number limits without any monotonicity condition on the velocity field in our previous *** paper aims to show that sufficient degeneracy in the tangential magnetic field at a non-degenerate critical point of the tangential velocity field of shear flow indeed yields instability as for the classical Prandtl equations without magnetic field studied by G′erard-Varet and Dormy(2010).This partially shows the necessity of the non-degeneracy in the tangential magnetic field for the stability of the boundary layer of MHD in 2D at least in Sobolev spaces.

关键词： MHD boundary layer Prandtl equations shear flows ill-posedness Sobolev spaces

Natural forest ALS-TLS point cloud data registration without control points

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Journal of Forestry Research 2023年第3期34卷 809-820页

作者： Jianpeng Zhang Jinliang Wang feng cheng Weifeng Ma Qianwei liu Guangjie liu Faculty of Geography Yunnan Normal UniversityKunming 650500People’s Republic of China Key Laboratory of Resources and Environmental Remote Sensing for Universities in Yunnan Kunming 650500People’s Republic of China Center for Geospatial Information Engineering and Technology of Yunnan Province Kunming 650500People’s Republic of China College of Resources and Environment Yunnan Agriculture UniversityKunming 650201People’s Republic of China

Airborne laser scanning(ALS)and terrestrial laser scanning(TLS)has attracted attention due to their forest parameter investigation and research *** is limited to obtaining fi ne structure information below the forest canopy due to the occlusion of trees in natural *** contrast,TLS is unable to gather fi ne structure information about the upper *** address the problem of incomplete acquisition of natural forest point cloud data by ALS and TLS on a single platform,this study proposes data registration without control *** ALS and TLS original data were cropped according to sample plot size,and the ALS point cloud data was converted into relative coordinates with the center of the cropped data as the *** same feature point pairs of the ALS and TLS point cloud data were then selected to register the point cloud *** initial registered point cloud data was fi nely and optimally registered via the iterative closest point(ICP)*** results show that the proposed method achieved highprecision registration of ALS and TLS point cloud data from two natural forest plots of Pinus yunnanensis *** Picea asperata *** included diff erent species and *** average registration accuracy of 0.06 m and 0.09 m were obtained for *** and ***,respectively.

关键词： Airborne laser scanning(ALS) Terrestrial laser scanning(TLS) Registration Natural forest Iterative closest point(ICP)algorithm

Achieving near-infrared-light-mediated switchable friction regulation on MXene-based double network hydrogels

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Friction 2024年第1期12卷 39-51页

作者： Pengxi WU cheng ZENG Jinglun GUO Guoqiang liu feng ZHOU Weimin liu Center of Advanced Lubrication and Sealing Materials State Key Laboratory of Solidification ProcessingNorthwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

MXene possesses great potential in enriching the functionalities of hydrogels due to its unique metallic conductivity,high aspect ratio,near-infrared light(NIR light)responsiveness,and wide tunability,however,the poor compatibility of MXene with hydrogels limits further *** this work,we report a uniformly dispersed MXene-functionalized poly-N-isopropylacrylamide(PNIPAM)/poly-2-acrylamido-2-methyl-1-propanesulfonic acid(PAMPS)double network hydrogel(M–DN hydrogel)that can achieve switchable friction regulation by using the NIR *** dispersity of MXene in hydrogels was significantly improved by incorporating the chitosan(CS)*** M–DN hydrogel showed much low coefficient of friction(COF)at 25℃ due to the presence of hydration layer on hydrogel *** illuminating with the NIR light,M–DN hydrogel with good photothermal effect rapidly raised the temperature to above the lower critical solution temperature(LCST),which led to an obvious increase of surface COF owing to the destruction of the hydration *** addition,M–DN friction control hydrogel showed good recyclability and controllability by tuning“on-off”of the NIR *** work highlights the construction of functional MXene hydrogels for intelligent lubrication,which provides insight for interface sensing,controlled transmission,and flexible robotic arms.

关键词： MXene dispersion photothermal hydrogel near-infrared(NIR)light friction modulation