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Microstructures and properties of Cu-Cr-W composite coatings fabricated by surface mechanical alloying technique

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Rare Metals 2022年第12期41卷 4248-4256页

作者： jia-ping zhang Xiao-Mei Feng Yi-Fu Shen Cheng Chen Cui-Yuan Duan College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Cu-Cr-W composite coatings were prepared by mechanical alloying(MA)method using different powder ratios,rotational speeds and milling *** micro structures and chemical compositions of as-synthesized coatings were analyzed by scanning electron microscopy(SEM)and energy-dispersive spectroscopy(EDS).Phases of ball-milled powders were identified by X-ray diffraction(XRD).The results indicate that the coating fabricated with powder ratio of 40 wt%Cu-Cr-W has better surface and cross-sectional microstructures and higher *** comparisons of cross-sectional micro structures of the coatings fabricated at different rotational speeds suggest that rotational speed of 300 r·min-1is the optimal for fabrication the coating,and the optimal milling time for the formation of coating is 7 *** results of microhardness test show that the hardness of the substrate is largely improved because of the as-fabricated *** results of the friction and wear tests indicate that the wear resistance of the copper substrate is improved after the deposition of Cu-Cr-W coating on *** coating fabricated for 7 h exhibits the lowest friction coefficient,indicating its favorable friction and wear *** formation mechanism of the coating was *** to the investigations in this work,the Cu-Cr-W coating fabricated by MA method is considered to be effective to reinforce the copper substrate.

关键词： Mechanical alloying Composite coating Powder ratio Processing parameter

Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

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Petroleum Science 2024年第3期21卷 2048-2065页

作者： Qing-ping Li Jin-Ya zhang jia-Xiang zhang Yong-Xue zhang CNOOC Research Institute Company Limited Beijing100028China State Key Laboratory of Natural Gas Hydrate Beijing100028China College of Mechanical and Transportation Engineering China University of PetroleumBeijing2249China

Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump *** mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation ***(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh *** results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually *** the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely *** maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance *** mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial *** with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and *** actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

关键词： Multiphase pump Liquid film seal Pressure disturbance wave Dynamic response characteristics

Rheological Behaviors of Polymers with Nanoparticles Tethered at Each End

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Chinese Journal of Polymer Science 2024年第3期42卷 400-406,I0009页

作者： Song-Qi zhang Wen-Qing Wang jia-ping Lin Li-Quan Wang Shanghai Key Laboratory of Advanced Polymeric Materials Key Laboratory for Ultrafine Materials of Ministry of EducationSchool of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China

The polymer with nanoparticles tethered at each end is a unique model for unraveling the effect of chain ends on the polymer dynamics. We investigated the rheological behavior of this kind of polymer by using nonequilibrium molecular dynamics simulation. The effect of polymer lengths and nanoparticle radii on the complex moduli and viscosity was examined. The dependence of complex moduli on the frequency becomes less pronounced as the polymer is short or the nanoparticle is large. The shear thinning behavior was revealed for these systems, and the scaling exponent of complex viscosity with respect to the frequency was found to change from-1/2 to-3/4 as the polymer shortens or the nanoparticle enlarges. The rheological behavior was further explained by analyzing the mean square distance of nanoparticles. The simulation results were compared with the existing experimental finding, showing an agreement. The work provides information for understanding the chain end effect on polymer rheology.

关键词： Polymer rheology Modulus Viscosity Molecular dynamics

Furan-derived Schiff base covalent adaptable thermosets with recyclability and anti-flammability

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Green Chemical Engineering 2024年第3期5卷 364-373页

作者： ping zhang Shuyu jia Ruishi Xie Lin Chen Ying Xiong State Key Laboratory of Environment-friendly Energy Materials School of Materials Science and EngineeringSouthwest University of Science and TechnologyMianyang621010China

Conventional thermosetting polymers,mostly derived from nonrenewable petroleum resources,are not reprocessable and recyclable due to their highly cross-linked three-dimensional networks and face the disadvantage of high *** solve these issues,in this study,we synthesized a novel Schiff base covalent adaptable thermoset from a furan-derived tri-aldehyde monomer(TMFP)and a furan-derived di-amine monomer(DFDA).The as-prepared TMFP-DFDA-Vitrimer exhibited superior anti-flammability with a high limiting oxygen index(LOI)of 35.0%and a UL-94 V-0 rating,which was attributed to the excellent charring ***,TMFPDFDA-Vitrimer could also be conveniently recycled by chemical decomposition under a mixed hydrochloric acid/tetrahydrofuran(HCl/THF)*** recycling for 5 times,the thermal,mechanical,and flame retardant properties of the recycled TMFP-DFDA-Vitrimer retained almost unchanged compared to the original *** work provides a prime instance to develop advanced thermosetting polymers from abundant furan-based compounds.

关键词： Furan-based compounds Vitrimer Recyclability Flame retardancy

Estimating the optimal vegetation coverage for the dominant tree and shrub species over China's northwest drylands

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Science China Earth Sciences 2024年第5期67卷 1500-1517页

作者： Zhongdian zhang Xiaoxu jia ping ZHU Mingbin HUANG Lidong REN Ming’an SHAO School of Geographic Sciences Xinyang Normal UniversityXinyang 464000China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100190China Yellow River Delta Modern Agricultural Engineering Laboratory Chinese Academy of SciencesBeijing 100101China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYangling 712100China

Anthropogenic revegetation is an effective way to control soil erosion and restore degraded ecosystems in China's northwest drylands(NWD).However,excessive vegetation cover expansion has long been known to increase evapotranspiration,leading to reduced local water availability,which can in turn threaten the health and services of restored *** the optimal vegetation coverage(OVC)is critical for balancing the trade-off between plant growth and water consumption in water-stressed areas,yet quantitative assessments over the entire NWD are still *** this study,a modified Biome BioGeochemical Cycles(Biome-BGC)model was used to simulate the long-term(1961–2020)dynamics of actual evapotranspiration(ET_(a)),net primary productivity(NPP),and leaf area index(LAI)for the dominant non-native tree(*** and ***)and shrub(*** and ***)species at 246 meteorological sites over *** modified model incorporated the Richards equation to simulate transient unsaturated water flow in a multilayer soil module,and both soil and eco-physiological parameters required by the model were validated using field-observed ETadata for each *** distributions of OVC(given by the mean maximum LAI,LAI_(max))for the dominant species were determined within three hydrogeomorphic sub-areas(i.e.,the loess hilly-gully sub-area,the windy and sandy sub-area,and the desert sub-area).The modified Biome-BGC model performed well in terms of simulating ET_(a) dynamics for the four plant *** distributions of mean ET_a,NPP,and LAI_(max)generally exhibited patterns similar to mean annual precipitation(MAP).In the loess hilly-gully sub-area(MAP:210 to 710 mm),the OVC respectively ranged from 1.7 to 2.9 and 0.8 to 2.9 for *** and *** the windy and sandy sub-area(MAP:135 to 500 mm),the OVC ranged from 0.3 to 3.3,0.5 to 2.6 and 0.6 to 2.1for ***,*** and ***,*** the desert sub-

关键词： Optimal vegetation coverage Water balance Leaf area index Biome-BGC model Dryland

Preparation of maximally-entangled states with multiple cat-state qutrits in circuit QED

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Frontiers of physics 2024年第3期19卷 239-251页

作者： Chui-ping Yang jia-Heng Ni Liang Bin Yu zhang Yang Yu Qi-ping Su Department of Physics Hangzhou Normal UniversityHangzhou 311121China School of Physics Nanjing UniversityNanjing 210093China Institute for Quantum Science and Technology University of CalgaryAlberta T2N 1N4Canada

In recent years,cat-state encoding and high-dimensional entanglement have attracted much ***,previous works are limited to generation of entangled states of cat-state qubits(two-dimensional entanglement with cat-state encoding),while how to prepare entangled states of cat-state qutrits or qudits(high-dimensional entanglement with cat-state encoding)has not been *** here propose to generate a maximally-entangled state of multiple cat-state qutrits(three-dimensional entanglement by cat-state encoding)in circuit *** entangled state is prepared with multiple microwave cavities coupled to a superconducting flux ququart(a four-level quantum system).This proposal operates essentially by the cavity-qutrit dispersive *** circuit hardware resource is minimized because only a coupler ququart is *** higher intermediate level of the ququart is occupied only for a short time,thereby decoherence from this level is greatly suppressed during the state ***,the state preparation time does not depend on the number of the qutrits,thus it does not increase with the number of the *** an example,our numerical simulations demonstrate that,with the present circuit QED technology,the high-fidelity preparation is feasible for a maximally-entangled state of two cat-state ***,we numerically analyze the effect of the inter-cavity crosstalk on the scalability of this *** proposal is universal and can be extended to accomplish the same task with multiple microwave or optical cavities coupled to a natural or artificial four-level atom.

关键词： maximally-entangled states cat state qutrit circuit QED

High-rate lithium-ion battery performance of a ternary sea urchin-shaped CoNiO_(2)@NiP_(6)Mo_(18)/CNTs composites

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Journal of Energy Chemistry 2024年第9期96卷 516-525页

作者： Li-ping Cui Shuang Sun Kai Yu Shu zhang Mei-lin Wang jia-jia Chen Bai-bin Zhou Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of EducationSchool of Chemistry and Chemical EngineeringHarbin Normal UniversityHarbin 150025HeilongjiangChina State Key Laboratory of Physical Chemistry of Solid Surfaces Department of ChemistryCollege of Chemistry and Chemical EngineeringCollaborative Innovation Centre of Chemistry for Energy MaterialsXiamen UniversityXiamen 361005FujianChina

Bimetallic oxides are attractive anode materials for lithium-ion batteries(LIBs)due to their large theoretical ***,the low conductivity,short cycle life,and poor rate capability are the bottlenecks for their further *** overcome above issues,the basket-like polymolybdate(NiP_(6)Mo_(18))and carbon nanotubes(CNTs)were uniformly embedded on the urchin-shaped CoNiO_(2)nanospheres to yield a ternary composites CoNiO_(2)@NiP_(6)Mo_(18)/CNTs via electrostatic *** multi-level morphology of urchin spinules accelerates the diffusion rate of Li^(+);CNT improves the conductivity and enhances cycle stability of the material;and heteropoly acid contributes more redox activity ***,CoNiO_(2)@NiP_(6)Mo_(18)/CNTs as an anode of LIBs exhibits a high initial capacity(1396.7 mA h g^(−1)at 0.1 A g^(−1)),long-term cycling stability(750.2 mA h g^(−1)after 300 cycles),and rate performance(450.3 mA h g^(−1)at 2 A g^(−1)),which are superior to reported metallic oxides anode of *** density functional theory(DFT)and kinetic mechanism suggest that CoNiO_(2)@NiP_(6)Mo_(18)/CNTs delivers an outstanding pseudocapacitance and rapid Li^(+)diffusion behaviors,which is due to the rich surface area of the urchin-like CoNiO_(2)with the uniform embeddedness of NiP_(6)Mo_(18)and *** study provides a new idea for optimizing the performance of bimetallic oxides and developing high-rate lithium-ion battery composites.

关键词： Bi-metal oxides Transition metal oxides Polyoxometalates Nanocomposite LIBs

Preparation of single atom catalysts for high sensitive gas sensing

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International Journal of Extreme Manufacturing 2024年第3期6卷 216-248页

作者： Xinxin He ping Guo Xuyang An Yuyang Li jiatai Chen Xingyu zhang Lifeng Wang Mingjin Dai Chaoliang Tan jia zhang Key Laboratory of Microsystems and Microstructure Manufacturing Ministry of EducationHarbin Institute of TechnologyHarbin 150080People’s Republic of China Institute for Frontier Materials Deakin UniversityWaurn Ponds CampusLocked Bag 20000Victoria 3220Australia School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore Department of Electrical and Electronic Engineering The University of Hong KongPokfulam RoadHong Kong Special Administrative Region of China 999077People’s Republic of China Chongqing Research Institute Harbin Institute of TechnologyChongqing 401120People’s Republic of China

Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical *** the semiconductor-based electrical gas sensor,the core is the catalysis process of target gas molecules on the sensitive *** this context,the SACs offer great potential for highly sensitive and selective gas sensing,however,only some of the bubbles come to the *** facilitate practical applications,we present a comprehensive review of the preparation strategies for SACs,with a focus on overcoming the challenges of aggregation and low *** research efforts have been devoted to investigating the gas sensing mechanism,exploring sensitive materials,optimizing device structures,and refining signal post-processing ***,the challenges and future perspectives on the SACs based gas sensing are presented.

关键词： single atom catalysts preparation sensing mechanism gas sensing

Self organizing optimization and phase transition in reinforcement learning minority game system

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Frontiers of physics 2024年第4期19卷 297-309页

作者： Si-ping zhang jia-Qi Dong Hui-Yu zhang Yi-Xuan Lü Jue Wang Zi-Gang Huang Key Laboratory of Biomedical Information Engineering of Ministry of Education Key Laboratory of Neuro-informatics&Rehabilitation Engineering of Ministry of Civil Affairsand Institute of Health and Rehabilitation ScienceSchool of Life Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Lanzhou Center for Theoretical Physics and Key Laboratory of Theoretical Physics of Gansu Province Lanzhou UniversityLanzhou 730000China

Whether the complex game system composed of a large number of artificial intelligence(AI)agents empowered with reinforcement learning can produce extremely favorable collective behaviors just through the way of agent self-exploration is a matter of practical *** this paper,we address this question by combining the typical theoretical model of resource allocation system,the minority game model,with reinforcement *** individual participating in the game is set to have a certain degree of intelligence based on reinforcement learning *** particular,we demonstrate that as AI agents gradually becomes familiar with the unknown environment and tries to provide optimal actions to maximize payoff,the whole system continues to approach the optimal state under certain parameter combinations,herding is effectively suppressed by an oscillating collective behavior which is a self-organizing pattern without any external *** interesting phenomenon is that a first-order phase transition is revealed based on some numerical results in our multi-agents system with reinforcement *** order to further understand the dynamic behavior of agent learning,we define and analyze the conversion path of belief mode,and find that the self-organizing condensation of belief modes appeared for the given trial and error rates in the AI ***,we provide a detection method for period-two oscillation collective pattern emergence based on the Kullback–Leibler divergence and give the parameter position where the period-two appears.

关键词： oscillatory evolution collective behaviors phase transition reinforcement learning minority game