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New discrete element models for elastoplastic problems

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Acta Mechanica Sinica 2009年第5期25卷 629-637页

作者： ming cheng Weifu liu Kaixin liu LTCS and Department of Mechanics and Aerospace Engineering,College of Engineering, Peking University, 100871 Beijing, China LTCS and Department of Mechanics and Aerospace Engineering College of Engineering Peking University Beijing China

The discrete element method （DEM） has attractive features for problems with severe damages, but lack of theoretical basis for continua behavior especially for nonlinear behavior has seriously restricted its application. The present study proposes a new approach to developing the DEM as a general and robust technique for modeling the elastoplastic behavior of solid materials. New types of connective links between elements are proposed, the interelement parameters are theoretically determined based on the principle of energy equivalence and a yield criterion and a flow rule for DEM are given for describing nonlinear behavior of materials. Moreover, a numerical scheme, which can be applied to modeling the behavior of a continuum as well as the transformation from a continuum to a discontinuum, is obtained by introducing a fracture criterion and a contact model into the DEM. The elastoplastic stress wave propagations and the tensile failure process of a steel plate are simulated, and the numerical results agree well with those obtained from the finite element method （FEM） and corresponding experiment, and thus the accuracy and efficiency of the DEM scheme are demonstrated.

关键词： DEM Continuum Plasticity Fracture

Facet effects on bimetallic ZnSn hydroxide microcrystals for selective electrochemical CO2 reduction

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Green Energy & Environment 2024年第8期9卷 1314-1320页

作者： liu Han cheng-wei Wang Shan-shan Luo Ying-tang Zhou Bing Li ming liu School of Chemistry and Chemical Engineering Harbin Institute of Technology National Engineering Research Center for Marine Aquaculture Marine Science and Technology CollegeZhejiang Ocean University

Employing crystal facets to regulate the catalytic properties in electrocatalytic carbon dioxide reduction reaction（eCO2RR） has been well demonstrated on electrocatalysts containing single metals but rarely explored for bimetallic systems. Here, we synthesize Zn Sn（OH）6（ZSO）microcrystals（MCs） with distinct facets and investigate the facet effects in eCO2RR. Electrochemical studies and in situ Fourier Transform Infrared Spectroscopy（in situ-FTIR） reveal that ZSO MCs produce mainly C1 products of HCOOH and CO. The {111} facet of the ZSO MCS exhibits higher selectivity and faradaic efficiency（FE） than that of the {100} facet over a wide range of potentials（-0.9 V ～-1.3 V versus RHE）. Density Functional Theory（DFT） calculations elucidate that the {111} facet is favorable to the adsorption/activation of CO2molecules,the formation of intermediate in the rate-determining step, and the desorption of C1 products of CO and HCOOH molecules.

关键词： ZnSn(OH) 6 Crystal facets Electrochemical carbon dioxide reduction C1 product Density functional theory

Study of muon tomographic imaging for high-Z material detection with a Micromegas-based tracking system

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Radiation Detection Technology and Methods 2020年第3期4卷 263-268页

作者： cheng-ming liu Qun-Gang Wen Zhi-Yong Zhang Guang-Shun Huang State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China AnHui University Hefei 230061China

Purpose To study the cosmic ray muon tomographic imaging of high-Z material with Micromegas-based tracking *** A high-spatial-resolution tracking system was set up with the micro-mesh gaseous structure(Micromegas)detec-tors in order to study the muon tomographic imaging *** layers of 90 mm×90 mm one-dimensional readout Micromegas were used to construct a tracking *** and conclusion The imaging test using some metallic bars was performed with cosmic ray muons.A two-dimensional imaging of the test object was presented with a newly proposed ratio *** result of this work shows that the ratio algorithm is well performed.

关键词： Muon tomography imaging Micromegas detector Ratio algorithm High spatial resolution

First-order multiples imaging aided by water bottom

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Petroleum Science 2021年第6期18卷 1650-1661页

作者： Zhen-Hua Xu Sheng-He Wu ming-cheng liu Jun-Shou Zhao Zhao-Hui Chen Ke Zhang Jia-Jia Zhang Zhao liu State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum-BeijingBeijing 102249China College of Geosciences China University of Petroleum-BeijingBeijing102249China Bohai Petroleum Research Institute CNOOC Tianjin BranchTianjin300459China Sinopec Geophysical Research Institute NanjingJiangsu211103China

Surface-related multiples frequently propagate into the subsurface and contain abundant information on small reflection *** with the conventional migration of primaries,migration of multiples offers complementary illumination and a higher vertical ***,crosstalk artifacts caused by unrelated multiples during reverse time migration(RTM)using multiples severely degrade the reliability and interpretation of the final migration ***,we proposed RTM using first-order receiver-side water-bottom-related multiples for eliminating crosstalk artifacts and enhancing vertical *** first backward propagate the first-order receiver-side water-bottom-related multiples using a water-layer model,followed by saving the upper boundary *** we produce the source wavefield using a seismic wavelet and the receiver wavefield by back-extrapolating the saved ***,the cross-correlation imaging condition is applied to generate the final *** method transforms the receiver-side multiples into primaries,followed by the conventional migration processing *** examples using synthetic datasets demonstrate that our method significantly enhances the imaging quality by eliminating crosstalk artifacts and improving the resolution.

关键词： Surface-related multiples Multiples imaging Multiples elimination

On-demand engineerable visible spectrum by fine control of electrochemical reactions

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National Science Review 2024年第3期11卷 239-249页

作者： Qirong liu Lei liu Yongping Zheng Min Li Baofu Ding Xungang Diao Hui-ming cheng Yongbing Tang Advanced Energy Storage Technology Research Center Shenzhen Institute of Advanced TechnologyChinese Academy of Sciences Institute of Technology for Carbon Neutrality Shenzhen Institute of Advanced Technology Chinese Academy of Sciences School of Energy and Power Engineering North University of China School of Resource Environment and Safety EngineeringHunan University of Science and Technology School of Energy and Power Engineering Beihang University Shenzhen Key Laboratory of Energy Materials for Carbon Neutrality Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

Tunability of optical performance is one of the key technologies for adaptive optoelectronic applications,such as camouflage clothing, displays, and infrared shielding. High-precision spectral tunability is of great importance for some special applications with on-demand adaptability but remains challenging. Here we demonstrate a galvanostatic control strategy to achieve this goal, relying on the finding of the quantitative correlation between optical properties and electrochemical reactions within materials. An electrochromic electro-optical efficiency index is established to optically fingerprint and precisely identify electrochemical redox reactions in the electrochromic device. Consequently, the charge-transfer process during galvanostatic electrochemical reaction can be quantitatively regulated, permitting precise control over the final optical performance and on-demand adaptability of electrochromic devices as evidenced by an ultralow deviation of <3.0%. These findings not only provide opportunities for future adaptive optoelectronic applications with strict demand on precise spectral tunability but also will promote in situ quantitative research in a wide range of spectroelectrochemistry, electrochemical energy storage, electrocatalysis, and material chemistry.

关键词： electrochromics fine control spectral tunability high precision galvanostatic control

Energy correction based on fluorescence attenuation of DAMPE

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Research in Astronomy and Astrophysics 2020年第8期20卷 163-168页

作者： Li-Bo Wu Yun-Long Zhang Zhi-Yong Zhang Yi-Feng Wei Si-cheng Wen Hao-Ting Dai cheng-ming liu Xiao-Lian Wang Zi-Zong Xu Guang-Shun Huang State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

The major scientific goals of the DArk Matter Particle Explorer(DAMPE)are to study cosmicray electrons(including positrons)and gamma rays from 5 GeV to 10 TeV and nuclei from Z=1 to 26 up to 100 *** deposited energy measured by the Bismuth Germanate Oxide(BGO)calorimeter of DAMPE is affected by fluorescence attenuation in BGO crystals that are 600 mm *** this work,an in-orbit attenuation calibration method is reported,and energy correction of the sensitive detector unit of the BGO calorimeter is also presented.

关键词： DAMPE BGO calorimeter fluorescence attenuation dark matter

Leflunomide: A versatile additive for defect reduction, enhanced optoelectronic properties and environmental stability of perovskite films

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Nano Research 2024年第4期17卷 2628-2637页

作者： Dingyue Sun ming Peng Taijin Wang Longju Yi Shizuo Zhang Feng liu Gary J.cheng The Institute of Technological Sciences Wuhan UniversityWuhan 430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China School of Industrial Engineering Purdue UniversityWest LafayetteIN 47906USA

The development of perovskite photoelectric devices with excellent performance is largely dependent on the defects in the perovskite *** address this issue,a specific drug,leflunomide(LF,C_(12)H_(9)F_(3)N_(2)O_(2)),was incorporated into the perovskite to reduce defects and improve its photoelectric *** is believed that the C=O bond on LF molecule can interact with the uncoordinated Pb2+of the perovskite,thereby reducing non-radiative *** novel approach of incorporating LF into perovskite films has the potential to revolutionize the development of high-performance perovskite photoelectric *** trifluoromethyl functional(–CF_(3))group on LF can form a protective layer on the surface of the perovskite film,shielding it from water ***,LF can be utilized to alter the nucleation position of perovskite,thus minimizing the number of defects and optimizing the film ***,the LF-doped perovskite film displays low trap density and high photoelectric *** LF-doped perovskite film showed a trap density of 8.28×10^(11),which is notably lower than the 2.04×10^(12) of the perovskite film without *** responsivity and detectivity of the LF-doped perovskite photodetector were 0.771 A/W and 2.81×10^(11) Jones,respectively,which are much higher than the 0.23 A/W and 1.06×10^(10) Jones of the LF-undoped perovskite ***,the LF-doped photodetector maintained an initial photocurrent of 86%after 30 days of storage in air,indicating drastically increased environmental *** strongly suggests that LF is an effective additive for perovskites utilized in optoelectronic devices with high performance.

关键词： leflunomide additive engineering defect passivation perovskite

Single-wall carbon nanotube fiber non-woven fabrics with a high electrothermal heating response

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Nano Research 2024年第6期17卷 5621-5628页

作者： Xinyu Jiao Lele Xu Xinyang Sun Chao Shi Peng-Xiang Hou Chang liu Hui-ming cheng Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Faculty of Materials Science and Engineering/Institute of Technology for Carbon Neutrality Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Carbon nanotube(CNT)fibers have great promise for constructing multifunctional fabrics with high electrical conductivity,good electro-heating ability,excellent flexibility,and a low ***,the inter-fiber contacts in the fabric greatly reduce these advantages and limit their ***,a simple pressure-fusing method to fabricate single-wall CNT(SWCNT)fiber non-woven fabrics(NWFs)that are composed of interconnected SWCNT fibers with fused joints is reported,which have good flexibility,a low density of 0.46 g/cm^(3),a high electrical conductivity of 3.7×10^(5)S/m,and a record high specific electrical conductivity of 803(S·m^(2))/*** also showed excellent electrical heating ability,so that a temperature of~160℃was rapidly reached at a low voltage of 2 *** with their low density,the SWCNT fiber NWFs are promising for use as a heating unit for low temperature battery protection and de-icing applications.

关键词： carbon nanotube fiber nonwoven fabrics fusing electrothermal heating

Reactive oxygen species:Multidimensional regulators of plant adaptation to abiotic stress and development

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Journal of Integrative Plant Biology 2024年第3期66卷 330-367页

作者： Pengtao Wang Wen-cheng liu Chao Han Situ Wang ming-Yi Bai Chun-Peng Song State Key Laboratory of Crop Stress Adaptation and Improvement School of Life SciencesHenan UniversityKaifeng 475004China The Key Laboratory of Plant Development and Environmental Adaptation Biology Ministry of EducationSchool of Life SciencesShandong UniversityQingdao 266237China Faculty of Science McGill UniversityMontreal H3B1X8Canada

Reactive oxygen species(ROS)are produced as undesirable by-products of metabolism in various cellular compartments,especially in response to unfavorable environmental conditions,throughout the life cycle of *** ROS production disrupts normal cellular function and leads to oxidative *** cope with excessive ROS,plants are equipped with a sophisticated antioxidative defense system consisting of enzymatic and non-enzymatic components that scavenge ROS or inhibit their harmful effects on ***,when maintained at relatively low levels,ROS act as signaling molecules that regulate plant growth,development,and adaptation to adverse ***,we provide an overview of current approaches for detecting *** also discuss recent advances in understanding ROS signaling,ROS metabolism,and the roles of ROS in plant growth and responses to various abiotic stresses.

关键词： abiotic stress growth and development plant reactive oxygen species