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CFD-DEM simulation of high density particles fluidization behaviors in 3D conical spouted beds

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Particuology 2024年第5期88卷 266-281页

作者： Lin Jiang Mofan Qiu Rongzheng liu Bing liu Youlin Shao Malin liu Institute of Nuclear and New Energy technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing 100084China

the spouted bed has been used in the coating process of high-density nuclear fuel *** particle fluidization behaviors in pseudo-2D and 3D spouted beds were simulated and *** effects of four independent variables(cone angle,particle density,inlet gas velocity,and particle loading)on particle fluidization behaviors in the 3D spouted bed were investigated *** cone angle effect on fluidization mechanism was studied quantitatively first time.A new fluidization quality index was proposed based on the particle entrainment principle,and an extreme value was obtained when the cone angle was 60°,considered to be the optimum value for the 3D conical spouted *** was indicated the gas–solid contact efficiency can be kept up if the gas velocity was proportional to ρ_(p)^(0.65) and N_(p)^(0.78) when the particle density or loading was *** results will be useful for geometry and operation parameters design of the 3D conical spouted bed and helpful for developing the fluidization mechanism of high-density particles.

关键词： Spouted bed High-density particle CFD-DEM Fluidization quality index Particle loading

Lanthanide-based microlasers:Synthesis,structures,and biomedical applications

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Nano Research 2024年第1期17卷 97-111页

作者： Qian Zhang Yawei liu Kai liu Hongjie Zhang Engineering Research Center of Advanced Rare Earth Materials(Ministry of Education) Department of ChemistryTsinghua UniversityBeijing 100084China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Xiangfu Laboratory Jiaxing 314102China

the large size of lasers limits their applications in confined spaces,such as in biosensing and in vivo brain tissue *** this regard,micron-sized lasers have been *** exhibit great potential for biological detecting,remote sensing,and depth tracking due to their small sizes,sensitive properties of their spectral fingerprints,and flexible positional modulation in the ***-based luminescent materials that possess long excited-state lifetime,narrow emission bandwidth,and upconversion behaviors are promising as gain mediums for novel *** addition,lanthanide-based microlasers could be generated under natural ambient conditions with pumped or continuous light sources,which significantly promotes the practical applications of *** progress in the design,synthesis,and biomedical applications of lanthanide-based microlasers has been outlined in this *** ions doped and upconverted lanthanide-based microlasers are highlighted,which exhibit advantageous structures,miniaturized dimensions,and high lasing *** applications of lanthanide-based microlasers are further discussed,the upconverted microlasers show great advantages for biological applications owing to their tunable excitation and emission characteristics and excellent environmental ***,perspectives and challenges in the field of lanthanide-based microlasers are presented.

关键词： microlasers lanthanide-based luminescent materials upconversion nanoparticles biological applications

Localization−delocalization transitions in non-Hermitian Aharonov−Bohm cages

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Frontiers of physics 2024年第3期19卷 39-50页

作者： Xiang Li Jin liu tao liu School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

A unique feature of non-Hermitian systems is the extreme sensitivity of the eigenspectrum to boundary conditions with the emergence of the non-Hermitian skin effect (NHSE). A NHSE originates from the point-gap topology of complex eigenspectrum, where an extensive number of eigenstates are anomalously localized at the boundary driven by nonreciprocal dissipation. two different approaches to create localization are disorder and flat-band spectrum, and their interplay can lead to the anomalous inverse Anderson localization, where the Bernoulli anti-symmetric disorder induces mobility in a full-flat band system in the presence of Aharonov−Bohm (AB) Cage. In this work, we study the localization−delocalization transitions due to the interplay of the point-gap topology, flat band and correlated disorder in the one-dimensional rhombic lattice, where both its Hermitian and non-Hermitian structures show AB cage in the presence of magnetic flux. Although it remains the coexistence of localization and delocalization for the Hermitian rhombic lattice in the presence of the random anti-symmetric disorder, it surprisingly becomes complete delocalization, accompanied by the emergence of NHSE. to further study the effects from the Bernoulli anti-symmetric disorder, we found the similar NHSE due to the interplay of the point-gap topology, correlated disorder and flat bands. Our anomalous localization−delocalization property can be experimentally tested in the classical physical platform, such as electrical circuit.

关键词： non-Hermitian skin effects disorder flat band localization−delocalization transition

Asymmetrically coordinated single atom Cu catalyst with unsaturated C-Cu-N structure for CO_(2) reduction to CO

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Nano Research 2024年第5期17卷 3911-3918页

作者： Zheng liu Yuxuan liu Jingqiao Zhang ting Cao Zhiyi Sun Juzhe liu Huishan Shang State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China SEPA Key Laboratory of Eco-Industry Chinese Research Academy of Environmental SciencesBeijing 100012China the Key Laboratory of Resources and Environmental System Optimization Ministry of EducationCollege of Environmental Science and EngineeringNorth China Electric Power UniversityBeijing 102206China School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China

Single atom catalysts(SACs)play a crucial role in energy catalysis due to their distinct coordination environment and high atomic utilization *** study focuses on the synthesis of a monatomic Cu catalyst with Cu-N1C1 coordination anchored to N-doped ti_(3)C_(2)t_(x) MXene(Cu SA@N-ti_(3)C_(2)t_(x))to achieve efficient reduction of CO_(2) to *** characterization,including morphology and multispectral analysis,confirmed the uniform distribution of asymmetrically coordinated Cu atoms in unsaturated C-Cu-N bridge fragments on ti_(3)C_(2)t_(x).the Cu SA@N-ti_(3)C_(2)t_(x) catalyst exhibited an excellent CO selectivity with Faraday efficiency of 97.4%at-0.58 V *** hydrogen electrode(RHE)and satisfactory *** in situ X-ray absorption fine structure(XAFS)results confirmed that the carbon dioxide reduction reaction(CO_(2)RR)product distribution is mainly affected by potential-dependent valence change of Cu *** findings highlight the extensive potential of tuning coordination structure of MXene-based single-atom catalysts for CO_(2) reduction reactions.

关键词： cooper single atom atomic regulation MXene ti_(3)C_(2)t_(x) CO_(2)reduction

Hard yet tough and self-lubricating(CuNitiNbCr)C_(x) high-entropy nanocomposite films:Effects of carbon content on structure and properties

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Journal of Materials Science & technology 2024年第6期173卷 20-30页

作者： Y.t.Li X.M.Chen X.K.Zeng M.liu X.Jiang Y.X.Leng Key Laboratory of Advanced technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China School of Mechanical and Electrical Engineering Mianyang Teachers’CollegeMianyang 621000China

the single-phase high-entropy alloy film is difficult to meet severe friction conditions due to its low hardness and high friction ***-composite structure film is composed of at least two separated phases,showing the properties of strength and toughness integration and excellent wear *** design of nanocomposite structures can effectively improve the mechanical properties and tribological properties of high-entropy alloy *** this study,the(CuNitiNbCr)C_(x) nanocomposite high-entropy films(HEFs)integrated with high hardness,high toughness,and self-lubrication were synthesized by the double-target co-sputtering *** effect of carbon content on microstructure,mechanical properties,and tribological properties of(CuNitiNbCr)C_(x) films was *** the increase of carbon content in the HEFs,the carbon atoms preferentially react with ti,Nb,and Cr to form a(tiNbCr)C ceramic-reinforced phase,and then the excess carbon atoms precipitate in the form of amorphous carbon(a-C)lubricating phase in the *** structure of the HEFs changes from an amorphous structure to a nanocomposite structure of amorphous(amorphous CuNitiNbCr phase+a-C phase)/nanocrystalline(tiN-bCr)C *** the carbon content is about 21.2 at.%,the carbide phase in the film reaches saturation and the hardness and modulus of the films are highest,which are 18 GPa and 228 GPa,*** HEFs with a carbon content of 44.0 at.%show the best toughness and tribological properties with a friction coefficient of 0.16 and a wear rate of 2.4×10^(-6) mm^(3)/(N m),which is mainly attributed to the excellent resistance to fatigue crack growth and the interfacial lubricating layer formed in the friction *** nanocomposite(CuNitiNbCr)C_(x) HEFs show very promising application prospect in the field of friction protection.

关键词： High-entropy films Nanocomposite Double-target co-sputtering Strengthening-toughening tribological properties

Dynamic analysis of axle box bearings on the high-speed train caused by wheel-rail excitation

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 441-460页

作者： Qiaoying MA Shaopu YANG Yongqiang liu Baosen WANG Zechao liu State Key Laboratory of Mechanical behavior and System Safety of traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of transportation Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

to explore the impact of wheel-rail excitation on the dynamic performance of axle box bearings,a dynamic model of the high-speed train including axle box bearings is ***,the dynamic response characteristics of the axle box bearing are *** investigation focuses on the acceleration characteristics of bearing vibration under excitation of track irregularities and wheel *** addition,experiments on both normal and faulty bearings are conducted separately,and the correctness of the model and some conclusions are *** to the research,track irregularity is unfavorable for bearing fault detection based on resonance *** the same speed conditions,the acceleration peak of bearing is inversely proportional to the length of the wheel flat and directly proportional to its *** paper will contribute to a deeper understanding of the dynamic performance of axle box bearings.

关键词： high-speed train track irregularity wheel flat dynamic simulation

Enhancing corn stalk-based anaerobic digestion with different types of zero-valent iron added during the acidification stage:Performance and mechanism

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Journal of Environmental Sciences 2024年第11期145卷 64-74页

作者： Xiang liu Yue liu Min Wang Qianzhen Deng Hao Yang College of Agricultural Science and Engineering Hohai UniversityNanjing 210098China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China National and Local Joint Engineering Research Center of Ecological treatment technology for Urban Water Pollution Wenzhou UniversityWenzhou 325035China Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse Anhui Jianzhu UniversityHefei 230009China

Anaerobic digestion has been defined as a competitive approach to facilitate the recycling of corn ***,few studies have focused on the role of direct interspecies electron transfer(DIEt)pathway in the acidification stage under the addition of different particle sizes of zero-valent iron(ZVI).In this study,three types of ZVI,namely iron filings,iron powder and nanoscale iron,were investigated,respectively,to enhance its high-value *** in volatile fatty acids(VFAs)and methane(CH4)production associated with the underlyingmechanisms were emphatically *** indicated that the addition of ZVI could increase the concentration of VFAs,with the most outstanding performance observed with the use of nanoscale ***,the conversion of propionic acid to acetic acid was driven by adding ZVI with no between-group differences in acidizing ***,the substrate was more fully utilized when supplied with iron powder compared with other groups in methanogenic phase,thereby displaying the maximumCH4 yield with a value of 263.1 mL/(g total solids(tS)).However,adding nanoscale iron could signally shorten the digestion time(t80),saving 7 days in comparison to the group of iron powder.

关键词： Zero-valent iron Corn stalk Anaerobic digestion Volatile fatty acids Methane

CFD-DEM simulation of fluorination reaction in fluidized beds with local grid and time refinement method

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Particuology 2024年第1期84卷 145-157页

作者： Mofan Qiu Lin Jiang Rongzhen liu Yaping tang Malin liu Institute of Nuclear and New Energy technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing100084China

the gas-solid reaction process with wide particle size distribution is extensively used in the chemical engineering field,especially the particle reacts with the gas gradually,such as fluorination reactions in fluidized *** the computational fluid dynamics-discrete element method(CFD-DEM)is used for the coupling simulation of multiphase and polydisperse particle reaction system,the grid size directly affects the accuracy of flow field information and simulation of chemical ***,particle calculation time step will directly affect the efficiency of coupling *** this work,a local grid and time step refinement method is proposed to simulate multiphase and polydisperse particle fluid-ization reaction *** this method,the refined DEM grids are automatically generated in the computational domain around the fine particles,and the detailed fluid phase information is obtained with the interpolation *** the two-phase coupling process,particles are divided into different groups based on physical properties,each group has its own independent time *** multistage conical-cylindrical spouted bed is proposed for the fluorination reaction process;the operating gas ve-locity range of the polydisperse particle system is extended by the new design while the particle size distribution changes with the gas-solid reaction *** is demonstrated that the local grid and time step refinement method can improve the accuracy and efficiency of the traditional CFD-DEM method in the reaction process simulation,which describes a polydisperse particle system with wide particle size *** at improving the simulation accuracy and efficiency,this paper will be helpful for simulating the particle reaction process in the gas-solid fluidized bed and beneficial for the development of the CFD-DEM method.

关键词： CFD-DEM Polydisperse particle two-phase flow Fluidized bed

Bioinspired 4D Printing Shape-Memory Polyurethane Rhinoplasty Prosthesis for Dynamic Aesthetic Adjustment

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Journal of Bionic Engineering 2024年第3期21卷 1397-1411页

作者： Jiaqi liu Guiwei Li He liu Jincheng Wang Hui Wang Xue Gao Qingping liu Chenyu Wang Department of Plastic and Reconstructive Surgery The First Hospital of Jilin UniversityChangchun130021China Department of Orthopaedics The Second Hospital of Jilin UniversityChangchun130041China Key Laboratory of Bionic Engineering(Ministry of Education) Jilin UniversityChangchun130022China

the disparity between the postoperative outcomes of rhinoplasty and the expected results frequently necessitates secondary or multiple surgeries as a compensatory measure,greatly diminishing patient ***,there is renewed optimism for addressing these challenges through the innovative realm of Four-Dimensional(4D)*** groundbreaking technology enables three-dimensional objects with shape-memory properties to undergo predictable transformations under specific external ***,implants crafted using 4D printing offer significant potential for dynamic *** by worms in our research,we harnessed 4D printing to fabricate a Shape-Memory Polyurethane(SMPU)for use as a nasal augmentation *** choice of SMPU was guided by its Glass transition temperature(tg),which falls within the acceptable temperature range for the human *** attribute allowed for temperature-responsive intraoperative self-deformation and postoperative *** chosen animal model for experimentation was *** into account the anatomical structure of the rabbit nose,we designed and produced nasal augmentation prostheses with superior *** prostheses were then surgically implanted in a minimally invasive manner into the rabbit ***,they exhibited successful temperature-controlled in-surgery self-deformation according to the predetermined shape and non-invasive remodeling within a mere 9 days *** histological evaluations confirmed the practical viability of these prostheses in a living *** research findings posit that worm-inspired 4D-printed SMPU nasal prostheses hold significant promise for achieving dynamic aesthetic adjustments.

关键词： 4D printing Shape memory polyurethane Rhinoplasty Self-deformation Dynamic aesthetic adjustment