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Debris effect on the surface wear and damage evolution of counterpart materials subjected to contact sliding

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Advances in Manufacturing 2022年第1期10卷 72-86页

作者： Wei Li Liang-Chi zhang Chu-Han Wu zhen-xiang Cui Chao Niu Yan Wang School of Mechanical and Manufacturing Engineering The University of New South WalesSydneyNSW 2052Australia Shenzhen Key Laboratory of Cross-Scale Manufacturing Mechanics Southern University of Science and TechnologyShenzhen 518055GuangdongPeople’s Republic of China SUSTech Institute for Manufacturing Innovation Southern University of Science and TechnologyShenzhen 518055GuangdongPeople’s Republic of China Department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen 518055GuangdongPeople’s Republic of China Baoshan Iron&Steel Co. LtdShanghai 200941People’s Republic of China

This paper aims to explore the debris effect on surface wear and damage evolution of counterpart materials during contact sliding.A cylinder-on-flat testing configuration is used to investigate the wear behaviours of the contact *** explore the roles of wear debris,compressed air is applied to remove the debris in sliding *** comparative study demonstrates that the influence of debris removal is related to the surface properties of contact *** substantial wear debris accumulates on the tool surface,debris removal can considerably alter surface damage evolution,resulting in different friction transitions,distinct surface morphology of contact pair,as well as different rates of material *** has been found that the surface damage evolution will not reach a stable stage unless the increase of wear particle number ceases or the average size of wear particles becomes lower than a specific ***,the influence of debris removal reduces when the adhesion between the contact pair materials gets smaller.

关键词： Sliding wear Debris effect Debris distribution Contact sliding Metal forming

Electric transport properties and temperature stability of magnetoresistance of composite system between La_(8/9)Sr_(1/45)Na_(4/45)MnO_3 and Sb_2O_3

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Rare Metals 2013年第4期32卷 363-368页

作者： Gui-Ying Wang Yong-Gang Tang Qi-xiang Song Ming-Yu zhang zhen-Sheng Peng Anhui Key Laboratory of Spintronic and Nano-materials Research School of Mechanical and Electronic Engineering Suzhou University

The samples ofLa8/9Sr1/45Na4/45MnO3 （LSNMO）/x/2（Sb2O3） were prepared by the solid-state reaction method. The electric transport properties and the temperature stabil-ity of magnetoresistance （MR） of the samples were studied through the measurements of X-ray diffraction patterns, resistivity-temperature （ρ-T） curves, mass magnetization-temperature （σ-T） curves, and magnetoresistance-temper-ature （MR-T） curves. The results indicate that the p-Tcurves of the original material LSNMO show two peaks, and the phenomenon of two peaks of ρ-T curves disappears for the composite samples, which can be explained by a competition between surface-phase resistivity induced by boundary-dependent scattering and body-phase resistivity induced by paramagnetism-ferromagnetism transition. For all the sam-ples in the low temperature range, MR increases continu-ously with the decrease of temperature, which shows a characteristic of low-field magnetoresistance. However, MR basically keeps the same in the high temperature range. The paramagnetism-ferromagnetism transition is observed in the high temperature range due to a composite between perov-skite manganite and insulator, which can enhance the tem-perature of MR appearance in the high temperature range and make it to appear near room temperature. For the sample with x = 0.12, MR remains constant at the value of 7.5 % in the temperature range of 300-260 K, which achieves a tem-perature stability of MR near room temperature. In addition,for the sample with x = 0.16, MR is above 6.8 % in the high temperature range of 318-252 K （△T = 66 K）. MR almost remains constant in this temperature range, which favors the practical application of MR.

关键词： Electric transport property Temperaturestability of magnetoresistance Two-phase composite Perovskite manganite

Seismic fragility analysis of clay-pile-pier systems considering the optimization of ground motion intensity measures

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Earthquake Engineering and Engineering Vibration 2023年第4期22卷 965-977页

作者： zhang Panpan zhang Lei zhang zhen School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan 430070China

The performance of clay-pile-pier system under earthquake shaking was comprehensively examined via three-dimensional finite element analyses,in which the complex stress-strain relationships of a clay and piled pier system were depicted by a hyperbolic-hysteretic and an equivalent elastoplastic model,*** hundred twenty ground motions with varying peak accelerations were considered,along with the variations in bridge superstructure mass and pile flexural *** comparison studies suggested that peak pile-cap acceleration and peak pile-cap velocity are the optimal ground motion intensity measures for seismic responses of the pier and the pile,***,based on two optimal ground motion intensity measures and using curvature ductility to quantify different damage states,seismic fragility analyses were *** pier generally had no evident damage except when the bridge girder mass was equal to 960 t,which seemed to be comparatively insensitive to the varying pile flexural *** comparison,the pile was found to be more vulnerable to seismic damage and its failure probabilities tended to clearly reduce with the increment of pile flexural rigidity,while the influence of the bridge girder mass was relatively minor.

关键词： clay-pile-pier system seismic fragility analysis ground motion intensity measures damage probability

Research on manufacture technology of spherical fuel elements by dry-bag isostatic pressing

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Nuclear Science and Techniques 2022年第10期33卷 79-89页

作者： zhen-Ming Lu Wen-Ke zhang Jie zhang xiang-Wen Zhou Kai-Hong zhang Ma-Lin Liu Xuan-Ke Li Bing Liu Hubei Province Key Laboratory of Coal Conversion and New Carbon Materials Wuhan University of Science and TechnologyWuhan 430081China Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing 100084China

The steady development of high-temperature gas-cooled reactors(HTRs) has increased the requirements for the production cost and quality of fuel elements. Green fuel element pressing is one of the key steps to increase the production capacity. This paper proposes a proprietary vacuum dry-bag isostatic pressing(DIP) apparatus. The structural change of the matrix graphite powder during the DIP process was examined by analyzing the density change of the matrix graphite spheres with pressure. The soft molding process was simulated using the finite element method. The dimensional changes in the spheres during the pressing, carbonization, and purification stages were explored. The performance of the fuel matrix produced by the DIP method was comprehensively examined. The fuel matrix met the technical requirements and its anisotropy was significantly reduced. The DIP method can significantly improve both the production efficiency and quality of fuel elements. This will play a key role in meeting the huge demand for fuel elements of HTRs and molten salt reactors.

关键词： Dry-bag isostatic pressing High-temperature gas-cooled reactor(HTR) Spherical fuel element Finite element simulation Soft molding

Design Research of a Novel Aftercool-Humidifier Concept for Humid Air Turbine Cycle

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Journal of Thermal Science 2024年第3期33卷 951-969页

作者： zhang Junzheng XU zhen School of Energy and Power Engineering Shandong UniversityJi’nan250061China Shandong Engineering Laboratory for High-efficiency Energy Conservation and Energy Storage Technology&Equipment Shandong UniversityJi’nan250061China

Humid air turbine cycle(HAT)has potential of electrical efficiencies comparable to combined cycle,with lower investment cost and NO_(x) *** typical heat exchanger network of HAT consists of intercooler(if there is),aftercooler,recuperator,economizer and humidifier,which brings higher efficiency but makes the system more *** simplify HAT layout,a novel humidifier concept is proposed by integrating the aftercooler into traditional counter-current *** on this concept,a one-dimensional model including pressure drop and exergy calculation is established to distinguish the thermodynamic and hydrodynamic characteristics,and then the structural parameters,such as the number of rows and columns,tube diameter,pitch and type for a micro HAT are *** results show that the aftercool-humidifier plays the same role as original aftercooler and humidifier,and can match the in-tube air,out-tube air and water stream well with lower *** the case of micro HAT cycle,the volume of heat and mass transfer area can be reduced by 47%compared with traditional *** major thermal resistance occurred in the convection heat transfer process inside the tube;however,using enhanced tube cannot effectively improve the compactness of device.

关键词： humid air turbine cycle humidifier thermodynamic analysis one-dimensional model

Functional near-infrared spectroscopy can detect low-frequency hemodynamic oscillations in the prefrontal cortex during steady-state visual evoked potentialinducing periodic facial expression stimuli presentation

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Visual Computing for Industry,Biomedicine,and Art 2020年第1期3卷 321-328页

作者： Meng-Yun Wang Anzhe Yuan Juan zhang Yutao xiang zhen Yuan Faculty of Health Sciences University of MacaoTaipaMacao SAR 999078China Centre for Cognitive and Brain Sciences University of MacaoTaipaMacao SAR 999078China Eastside High School 1201 SE 43rd StreetGainesvilleFL 32641USA Faculty of Education University of MacaoTaipaMacao SAR 999078China

Brain oscillations are vital to cognitive functions,while disrupted oscillatory activity is linked to various brain *** high-frequency neural oscillations(>1 Hz)have been extensively studied in cognition,the neural mechanisms underlying low-frequency hemodynamic oscillations(LFHO)<1 Hz have not yet been fully *** way to examine oscillatory neural dynamics is to use a facial expression(FE)paradigm to induce steady-state visual evoked potentials(SSVEPs),which has been used in electroencephalography studies of high-frequency brain oscillation *** this study,LFHO during SSVEP-inducing periodic flickering stimuli presentation were inspected using functional near-infrared spectroscopy(fNIRS),in which hemodynamic responses in the prefrontal cortex were recorded while participants were passively viewing dynamic FEs flickering at 0.2 *** fast Fourier analysis results demonstrated that the power exhibited monochronic peaks at 0.2 Hz across all channels,indicating that the periodic events successfully elicited LFHO in the prefrontal *** importantly,measurement of LFHO can effectively distinguish the brain activation difference between different cognitive conditions,with happy FE presentation showing greater LFHO power than neutral FE *** results demonstrate that stimuli flashing at a given frequency can induce LFHO in the prefrontal cortex,which provides new insights into the cognitive mechanisms involved in slow oscillation.

关键词： Steady state visual evoked potentials Dynamic facial expressions Functional near-infrared spectroscopy Brain oscillation

Correlation between precipitates evolution and mechanical properties of Al-Sc-Zr alloy with Er additions

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Journal of Materials Science & Technology 2022年第4期99卷 61-72页

作者： Li Liu Jian-Tang Jiang xiang-Yuan Cui Bo zhang Liang zhen Simon P.Ringer School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China China-Ukraine Institute of Welding Guangdong Academy of SciencesGuangzhou 510651China School of Aerospace Mechanical and Mechatronic Engineeringand Australian Centre for Microscopy and MicroanalysisThe University of SydneyNew South Wales 2006Australia School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

Correlation between precipitates evolution and mechanical properties of Al-Sc-Zr alloy with Er additions during isothermal ageing were investigated by microhardness measurements,transmission electron microscopy,atom probe tomography and density functional theory-based *** results demonstrate that the Er additions significantly improve the hardness during elevated temperature ageing,especially at 400℃.This is mainly because Er additions increase the nucleation rate of the Al_(3)(Er,Sc,Zr)precipitates,resulting in a higher density of fine and uniform dispersion of L1_(2)structured ***-principles calculations demonstrate that the second nearest neighboring solute-solute interactions for the species Sc,Zr and Er are energetically favored–a key feature to rationalize the observed precipitate structure and the underlying formation *** sequential formation of the core/shell precipitates in the Er-free alloy and core/double-shell precipitates in the Er-containing alloy arises due to the different solute-solute and solute-vacancy interaction energies,and the relative diffusivities of the Er,Sc and Zr species in *** results shed light on the beneficial effects of Er additions on the agehardening behavior of Al-Sc-Zr alloy and provide guidance for designing the ageing treatments for the Al-Sc-Zr(-Er)alloys.

关键词： Al alloys Isothermal ageing Microhardness Transmission electron microscopy Atom probe tomography First-principles calculations

Anisotropy of nickel-based superalloy K418 fabricated by selective laser melting

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Progress in Natural Science:Materials International 2018年第4期28卷 496-504页

作者： zhen Chen Shenggui Chen zhengying Wei Lijuan zhang Pei Wei Bingheng Lu Shuzhe zhang Yu xiang State Key Laboratory of Manufacturing System Engineering Xi'an Jiaotong University Xi'an National Institute of Additive Manufacturing Co. Ltd. School of Mechanical Engineering Dongguan University of Technology School of Materials Science and Engineering South China University of Technology

Selective laser melting(SLM) is a promising additive manufacturing(AM) technology for fabricating the near net-shaped parts by selectively melting and solidifying a thin powder layer with a high-intensity laser beam according to the CAD data for arbitrary components. In this work, Ni-based superalloy K418 samples were fabricated by selective laser melting(SLM). To evaluate the anisotropic mechanical behavior of the SLM processed K418 samples with layer-by-layer melting, the samples were manufactured parallel(transverse specimens) and vertical(longitudinal specimens) to the building direction on the substrate. The microstructural anisotropy analysis was performed by optical microscopy(OM) and scanning electron microscopy(SEM).Electron backscatter diffraction(EBSD) analysis was used to identify their crystallographic preferred orientation(texture) and to correlate the anisotropy of the mechanical strength with the texture of the material. The results showed that the transverse specimens had slightly higher yield strength, but much significantly higher ductility than that of the transverse specimens with the elongated columnar grains along the building direction.

关键词： Selective laser melting Ni-based Superalloy K418 Anisotropy Microstructure Mechanical behavior

Astrometric Observations of NEA 1998 HH49 Using the Daocheng 50 cm Telescope

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Research in Astronomy and Astrophysics 2024年第7期24卷 71-78页

作者： Huan Xu xiang-Ming Cheng Yi-Gong zhang Teng-Fei Song zhen-Jun zhang Qing-Yu Peng Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Engineering Laboratory on Applied Astronomical Technology of Yunnan Kunming 650216China School of Information Engineering Kunming UniversityKunming 650214China School of Computer Science and Information Engineering Anyang Institute of TechnologyAnyang 455000China Department of Computer Science Jinan UniversityGuangzhou 510632China Sino-French Joint Laboratory for Astrometry Dynamics and Space ScienceJinan UniversityGuangzhou 510632China

This study details an astrometric observation campaign of the Near-Earth Asteroid 1998 HH49,conducted with the aim of refining our understanding of its physical *** the 50 cm telescope located at the Wumingshan Mountain in Daocheng,Sichuan,images were obtained over four nights,from 2023 October 19 to October *** observations were processed using Astrometrica software,facilitating the precise determination of the asteroid's *** observational results were compared with the ephemerides from three distinct sources to verify accuracy:the Jet Propulsion Laboratory(JPL)Horizons System,the Institut de Mécanique Céleste et de Calcul deséphémérides(IMCCE)Miriade,and the Near-Earth Objects Dynamic Site(NEODyS-2).When compared with the JPL ephemeris,a mean observed-minus-calculated(O-C)result of 0.″07 in the *** and-0.″35 in the *** was ***,the comparison with the IMCCE ephemeris yielded mean O-C results of 0.″08 in the *** and-0.″06 in the *** comparison with the NEODyS-2 ephemeris yielded the mean O-C results of 0.″06 in ***-0.″49 in *** study's findings demonstrate a general consistency between the observed data and the ephemeris predictions,with minor discrepancies observed across the data ***,both the JPL and NEODyS-2 ephemerides show that the residuals in the *** exceed those in the *** disparities may result from atmospheric differential color refraction,ephemeris discrepancies,observational errors,and other ***,it is worth noting that further investigation is required due to the potential influence of additional ***,the Daocheng 50 cm Telescope exhibits the ability to conduct high-precision positional measurements.

关键词： astrometry ephemerides time