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Tribological evaluation of thermoplastic polyurethane-based bearing materials under water lubrication:Effect of load,sliding speed,and temperature

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Friction 2024年第8期12卷 1801-1815页

作者： shaoli JIANG Janet ssWONG Debashis PUHAN tian YUAN Xiuqin BAI Chengqing YUAN state Key Laboratory of Maritime Technology and safety Wuhan University of TechnologyWuhan 430063China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK Yusuf Hamied Department of Chemistry University of CambridgeLensfield RoadCambridge CB21EWUK

Polymers are widely used in bearing *** the case of water-lubricated stern tube bearings,thermoplastic polyurethane(TPU)-based composites are used due to their excellent wear resis.ance,corrosion resis.ance,and tunable mechanical *** tribological performance,however,depends on operating *** this work,TPU was blended with carbon fiber,graphene platelet,and ultra-high molecular weight polyethylene(UHMWPE).Friction tests of TPU based-composites against copper countersurface were carried out in water to mimic the actual operating conditions of the *** of the resulting contacts were in the boundary lubrication regime,in which friction was attributed to both contact mechanics of asperities as well as water *** results show that the viscoelasticity of TPU has a considerable impact on its tribological *** lubrication at 50°C promotes the softening of polymer surface material during sliding,resulting in higher fluctuation in the coefficient of friction and wear *** is attributed to the reduced thermomechanical *** addition,schallamach waviness is observed on worn *** tribological properties of TPU are significantly improved by the inclusion of carbon fiber,graphene platelet,and *** formation of graphene transfer-layers.and UHMWPE transfer film reduces friction and wear loss,while the inclusion of carbon fiber enhances wear resis.ance due to improved mechanical properties.and load bearing capacity.

关键词： friction thermoplastic polyurethane(TPU) water-lubricated bearings graphene platelet carbon fibers ultra-high molecular weight polyethylene(UHMWPE)

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Frequency Domain Fatigue Evaluation on sCR Girth-Weld Based on structural stress

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China Ocean Engineering 2024年第2期38卷 255-270页

作者： ZHANG Long ZHAO tian-feng College of safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

The steel Catenary Riser(sCR)is a vital component for transporting oil and gas from the seabed to the floating *** harsh environmental conditions.and complex platform motion make the sCR’s girth-weld prone to fatigue *** structural stress fatigue theory and Master s-N curve method provide accurate predictions for the fatigue damage on the welded joints,which demonstrate significant potential and compatibility in multi-axial and random fatigue ***,we propose a new frequency fatigue model subjected to welded joints of sCR under multiaxial stress,which fully integrates the mesh-insensitive structural stress.and frequency domain random process.and transforms the conventional welding fatigue technique of sCR into a spectrum analysis technique utilizing structural ***,a full-scale FE model of sCR with welds is established to obtain the modal structural stress of the girth weld and the frequency response function(FRF)of modal coordinate,and a biaxial fatigue evaluation about the girth weld of the sCR can be achieved by taking the effects of multi-load correlation and pipe-soil interaction into *** research results indicate that the frequency-domain fatigue results are aligned with the time-domain results,meeting the fatigue evaluation requirements of the sCR.

关键词： sCR girth weld random vibration self(cross)power spectrum structural stress method biaxial fatigue damage

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Numerical investigation on characteristics of interfacial wave of liquid film in gas-liquid two-phase flow using OpenFOAM

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Chinese Journal of Aeronautics 2024年第2期37卷 233-248页

作者： Xiaoqi MA Yueshe WANG Jiaming tian state Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Liquid film cooling as.an advanced cooling technology is widely used in space *** operation of liquid film along the rocket combustion inner wall is crucial for thermal protection of rocket *** stability of liquid film is mainly determined by the characteristics of interfacial wave,which is rarely investigated right *** to improve the stability of thin film has become a hot *** view of this.an advanced model based on the conventional Volume of Fluid(VOF)model is adopted to investigate the characteristics of interfacial wave in gas-liquid flow by using OpenFOAM,and the mechanism of formation and development of wave is revealed intuitively through numerical *** effects from gas velocity,surface tension and dynamic viscosity of liquid(three factors)on the wave are studied *** can be found that the gas velocity is critical to the formation and development of wave,and four modes of droplets generation are illustrated in this ***,a gas vortex near the gas-liquid interface can induce formation of wave easily,so changing the gas vortex state can regulate formation and development of ***’s more,the change rules of three factors influencing on the interfacial wave are obtained,and the surface tension has a negative effect on the formation and development of wave only when the surface tension coefficient is above the critical value,whereas the dynamic viscosity has a positive effect in this ***,the maximum height and maximum slope angle of wave will level off as the gas velocity ***,the maximum slope angle of wave is usually no more than 38°,no matter what happens to the three factors.

关键词： Interfacial wave Gas-liquid Two-phase flow VOF model OpenFOAM

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Women’s empowerment and food consumption:Evidence from female-headed households in Tanzania

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Journal of Integrative Agriculture 2024年第2期23卷 457-467页

作者： Mosses Lufuke Xu tian College of Economics.and Management Nanjing Agricultural UniversityNanjing 210095China Department of Economics The University of DodomaDodoma 41218Tanzania College of Economics.and Management China Agricultural UniversityBeijing 100083China Academy of Global Food Economics.and Policy China Agricultural UniversityBeijing 100083China

Despite the growing recognition of women’s increasing role in the household and corresponding empowerment programs in sub-saharan Africa,intensive research on the relationship between women’s influence and household food consumption is *** the most recent(2017-2018)national household survey data from Tanzania,this study examined the influence of women’s empowerment on household food ***,we compared the monthly consumption of eight food categories between female-headed households(FHHs.and male-headed households(MHHs)using both descriptive statistics.and the propensity score matching(PsM)***,we adopted the two-stage Linear Expenditure system and Almost Ideal Demand system model(LEs-AIDs)to estimate income and price elasticities for the two household *** results show that FHHs consume bread and cereals,fish,oils.and fats,vegetables.and confectionery(sugar,jam,honey,chocolate,etc.)more than ***,FHHs have a significantly higher income elasticity of demand for all food groups than *** are also more price elastic than MHHs in meat,fish,oils,fats,sugar,jam,honey,chocolate,etc.

关键词： women’s empowerment food consumption income elasticity price elasticity

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An Energy Trading Method Based on Alliance Blockchain and Multi-signature

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Computers, Materials & Continua 2024年第2期78卷 1611-1629页

作者： Hongliang tian Jiaming Wang College of Electrical Engineering Northeast Electric Power UniversityJilin132012China

Blockchain,known for its secure encrypted ledger,has garnered attention in financial and data transfer realms,including the field of energy ***,the decentralized nature and identity anonymity of user nodes raise uncertainties in energy *** broadcast consensus authentication slows transaction speeds.and frequent single-point transactions in multi-node settings pose key exposure risks without protective measures during user *** address these,an alliance blockchain scheme is proposed,reducing the resource-intensive identity verification among *** integrates multi-signature functionality to fortify user resources.and transac-tion security.A novel multi-signature process within this framework involves neutral nodes established through central *** neutral nodes participate in multi-signature’s signing and verification,ensuring user identity and transaction content *** interactions among user nodes enhances transaction efficiency by minimizing communication overhead during verification and consensus *** assessments on reliability and operational speed highlight superior security performance,resilient against conventional attack *** shows that compared to traditional solutions,this scheme has advantages in terms of running *** conclusion,the alliance blockchain framework introduces a novel approach to tackle blockchain’s limitations in energy *** integrated multi-signature process,involving neutral nodes,significantly enhances security and *** scheme’s efficiency,validated through analytical assessments.and simulations,indicates robustness against security threats.and improved transactional *** research underscores the potential for improved security and efficiency in blockchain-enabled energy trading systems.

关键词： Alliance blockchain multi-signature energy trading security performance transaction efficiency

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Electrochemical anodic oxidation assisted fabrication of memristors

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International Journal of Extreme Manufacturing 2024年第3期6卷 250-272页

作者： shuai-Bin Hua tian Jin Xin Guo school of Materials science and Engineering State Key Laboratory of Material Processing and Die&Mould TechnologyHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China

Owing to the advantages of simple structure,low power consumption and high-density integration,memristors or memristive devices are attracting increasing attention in the fields such as next generation non-volatile memories,neuromorphic computation and data ***,the deposition of memristive films often requires expensive equipment,strict vacuum conditions,high energy consumption,and extended processing *** contrast,electrochemical anodizing can produce metal oxide films quickly(e.g.10 s) under ambient *** means of the anodizing technique,oxide films,oxide nanotubes,nanowires.and nanodots can be fabricated to prepare *** film thickness,nanostructures,defect concentrations,etc,can be varied to regulate device performances by adjusting oxidation parameters such as voltage,current and *** memristors fabricated by the anodic oxidation technique can achieve high device consistency,low variation,and ultrahigh yield *** article provides a comprehensive review of the research progress in the field of anodic oxidation assisted fabrication of ***,the principle of anodic oxidation is introduced;then,different types of memristors produced by anodic oxidation and their applications are presented;finally,features.and challenges of anodic oxidation for memristor production are elaborated.

关键词： anodic oxidation anodized aluminium oxide memristor resistive switching electrical properties

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Model-driven path planning for robotic plasma cutting of branch pipe with single Y-groove based on pipe-rotating scheme

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Advances in Manufacturing 2024年第1期12卷 94-107页

作者： Yan Liu Qiu Tang Xin-Cheng tian school of Control science and Engineering Shandong UniversityJinan250061People’s Republic of China Engineering Research Center of Intelligent Unmanned system Ministry of EducationJinan250061People’s Republic of China school of Mechanical and Electronic Engineering Shandong Jianzhu UniversityJinan250101People’s Republic of China

The automatic cutting of intersecting pipes is a challenging task in *** improved automation and accuracy,this paper proposes a model-driven path planning approach for the robotic plasma cutting of a branch pipe with a single ***,it summarizes the intersection forms.and introduces a dual-pipe intersection *** on this model,the moving three-plane structure(a description unit of the geometric characteristics of the intersecting curve)is constructed,and a geometric model of the branch pipe with a single Y-groove is ***,a novel mathematical model for plasma radius.and taper compensation is ***,the compensation model and groove model are integrated by establishing movable ***,to prevent collisions between the plasma torch and workpiece,the torch height is planned and a branch pipe-rotating scheme is *** the established models.and moving frames,the planned path description of cutting robot is provided in this novel *** accuracy of the proposed method is verified by simulations.and robotic cutting experiments.

关键词： Automatic groove cutting of intersecting pipes Model-driven robot path planning Plasma beam radius.and taper compensation

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Response of Insight resonance modes to environmental factors on Mars

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Earth and Planetary Physics 2024年第4期8卷 579-588页

作者： LiFei tian HuaJian Yao Laboratory of seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Chinese Academy of sciences Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng 230026China

The Insight(Interior Exploration using seismic Investigations,Geodesy,and Heat Transport)mission has recorded continuous ambient noise signals with many spectral peaks since its landing in *** majority of these peaks are modes produced by instrumental vibrations.and are associated with environmental factors,such as temperature and wind energy *** how these modes react under various conditions is crucial because it aids in identifying their *** this study,we analyzed the three-component spectra of Insight recordings from sols 184–738 and obtained the horizontal-to-vertical spectral ratio(HVsR,also known as H/V)curves for different time *** primary modes,such as those at 3.3 and 4.1 Hz,exhibited different behaviors,suggesting diverse *** modes were sensitive to low temperature and some were sensitive to high ***,we investigated the influence of wind and temperature on the H/V *** peak frequency was mainly affected by temperature,whereas the H/V value was not associated with the temperature or wind *** these modes.and elucidating their origins are significant for processing signals from Insight and can provide valuable guidance for designing future planetary seismometers.

关键词： Mars Insight spectral peaks H/V curve

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Distinct Electrical and Mechanical Responses of a Cu-10Fe Composite Prepared by Hot-Pressed sintering and Post Treatment

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Acta Metallurgica sinica(English Letters) 2024年第2期37卷 255-265页

作者： X.Y.Yue s.Y.Peng X.Zhang C.N.He Y.Z.tian Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang110819China school of Materials science and Engineering and tianjin Key Laboratory of Composite and Functional Materials Tianjin UniversityTianjin300350China Research Centre for Metallic Wires Northeastern UniversityShenyang110819China

A Cu-10wt%Fe composite was prepared through hot-pressed sintering,and the material was subsequently solution *** hot-pressed sintered and solution treated materials were rolled and *** precipitation behavior and performance changes were systematically studied by using s.anning electron microscopy and transmission electron *** contrast to the hot-pressed sintered specimen,the solution treatment significantly affects the thermal stability and properties of the Cu-10wt%Fe *** Cu-10wt%Fe composite was prepared after solid solution,cold rolling and aging at 773 K for 1 h,and it obtained excellent tensile strength of 494 MPa,uniform elongation of 16.3%,electrical conductivity of 51.1%IACs.and softening temperature of 838 *** for the distinct difference in thermal stability and properties between hot-pressed sintered and solution treated specimens were *** findings provide a theoretical basis for designing high-performance Cu-based in-situ composites by post treatment.

关键词： Cu-Fe composite Hot-pressed sintering Thermal stability strength Electrical conductivity

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Defect Engineering and Carbon supporting to Achieve Ni‑Doped CoP_(3) with High Catalytic Activities for Overall Water splitting

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Nano-Micro Letters 2024年第11期16卷 569-584页

作者： Daowei Zha Ruoxing Wang shijun tian Zhong‑Jie Jiang Zejun Xu Chu Qin Xiaoning tian Zhongqing Jiang Department of Physics Zhejiang Sci-Tech UniversityHangzhou 310018People’s Republic of China Department of Materials.and Chemical Engineering Ningbo University of TechnologyNingbo 315211People’s Republic of China Guangzhou Key Laboratory for surface Chemistry of Energy Materials Guangdong Engineering and Technology Research Center for Surface Chemistry of Energy MaterialsCollege of Environment and EnergySouth China University of TechnologyGuangzhou 510006People’s Republic of China

This work reports the use of defect engineering and carbon supporting to achieve metal-doped phosphides with high activities.and stabilities for the hydrogen evolution reaction(HER)and the oxygen evolution reaction(OER)in alkaline ***,the nitrogen-doped carbon nanofiber-supported Ni-doped CoP_(3) with rich P defects(Pv·)on the carbon cloth(p-NiCoP/NCFs@CC)is synthesized through a plasma-assisted phosphorization *** p-NiCoP/NCFs@CC is.an efficient and stable catalyst for the HER and the *** only needs overpotentials of 107 and 306 mV to drive 100 mA cm^(-2) for the HER and the OER,*** catalytic activities are higher than those of other catalysts reported *** high activities of the p-NiCoP/NCFs@CC mainly arise from its peculiar structural *** density functional theory calculation indicates that the Pv·richness,the Ni doping,and the carbon supporting can optimize the adsorption of the H atoms at the catalyst surface and promote the strong electronic couplings between the carbon nanofiber-supported p-NiCoP with the surface oxide layer formed during the OER *** gives the p-NiCoP/NCFs@CC with the high activities for the HER and the *** used in alkaline water electrolyzers,the p-NiCoP/NCFs@CC shows the superior activity and excellent stability for overall water splitting.

关键词： Plasma Electrocatalysis Hydrogen evolution reaction Oxygen evolution reaction Water splitting

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