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The variation of microbiological characteristics in surface waters during persistent precipitation

Frontiers of Environmental Science & Engineering 2024年第9期18卷 67-78页

作者： xinyan Xiao Chenlan Chen Haoran li lihua li xin Yu College of the Environment&Ecology Xiamen UniversityXiamen 361102China Fujian Key Laboratory of Coastal Pollution Prevention and Control Xiamen UniversityXiamen 361102China

Climate change leads to an increase in both the frequency and intensity of extreme *** runoff generated by extreme precipitation has a significant impact on ***,the impact of persistent precipitation on surface water quality is easy to neglect,due to its prolonged duration and lower-intensity *** study established eight sampling points within selected surface waters to observe the variation of microbial characteristics in a typical persistence precipitation *** primary difference between Furong Lake(FL)and Chengqian Reservoir(CR)was:the concentrations of dissolved organic carbon(DOC)were 21.3±0.7 and 8.3±1.5 mg/L in FL and CR,*** concentrations of R2A culturable bacteria and coliforms were 10^(4.57)and 10^(1.58)colony-forming units(CFU)/mL in FL,and were 10^(5.46)and 10^(2.64)CFU/mL in CR,*** precipitation,the maximum increase concentrations of R2A,NA culturable bacteria,and coliforms were 10^(0.75),10^(1.30),and 10^(2.27)CFU/mL in FL,***,microbial concentration and rainfall did not increase simultaneously,and a delay phenomenon was observed in the increasing microbial *** analyzing the concentration change trends and correlation of various water quality indicators during persistent precipitation,the significant correlation between the DOC concentration and the changes in the dominant species of microbial community structure was found in this study(plined,the abundance of hgcl_clade and CL500-29_marine_group ***,although persistent precipitation might not obviously alter the water quality visibly,it could still pose potential microbial risks.

关键词： Rainfall Dissolved organic carbon Culturable bacteria Water quality Microbial community structure Climate change

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Vibration transfer from underground train to multi-story building:Modelling and validation with in-situ test data

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Underground Space 2024年第6期19卷 301-316页

作者： li Wang xin Gao Caiyou Zhao Ping Wang Zili li Section of Railway Engineering Delft University of TechnologyStevinweg 12628CN DelftThe Netherlands Key Laboratory of High-speed Railway Engineering(Southwest Jiaotong University) Ministry of EducationChengdu 610031China

Excessive underground train-induced vibration becomes a serious environmental problem in *** investigate the vibration transfer from an underground train to a building nearby,an explicit-integration time-domain,three-dimensional finite element model is *** underground train,track,tunnel,soil layers and a typical multi-story building nearby are all fully coupled in this *** complex geometries involving the track components and the building are all modelled in detail,which makes the simulation of vibration transfer more realistic from the underground train to the *** model is validated with in-situ tests data and good agreements have been achieved between the numerical results and the experimental results both in time domain and frequency *** proposed model is applied to investigate the vibration transfer along the floors in the building and the influences of the soil stiffness on the vibration characteristics of the track-tunnel-soil-building *** is found that the building vibration induced by an underground train is dominant at the frequency determined by the P2 resonance and influenced by the vibration modes of the *** vertical vibration in the building decreases in a fluctuant pattern from the foundation to the top floor due to loss of high frequency contents and local *** vibration levels in different rooms at a same floor can be different due to the different local stiffness.A room with larger space thus smaller local stiffness usually has higher vibration *** soil layers make the tunnel lining and the building have more low frequency *** influence of the soil stiffness on the amplification scale along the floors of the building is found to be nonlinear and frequency-dependent,which needs to be further investigated.

关键词： Railway vibration Underground train Multi-story building vibration Finite element model Dynamic interaction

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Failure Analysis of Dissimilar Metal Welds between Ferritic Heat Resistant Steels and Austenitic Stainless Steels in Power Plant

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Chinese Journal of Mechanical Engineering 2024年第4期37卷 306-326页

作者： Xiaogang li Junfeng Nie xin Wang Kejian li Haiquan Zhang Institute of Nuclear and New Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China

This study analysed the failure of dissimilar metal welds(DMWs)between ferritic heat resistant steels and austenitic stainless steels and investigated its influencing factors by means of numerical simulation,microstructure characterization and mechanical property *** the long-term high-temperature service condition in practical power plant,the DMW failure mode was along the interface between nickel-based weld metal(WM)and ferritic heat resistant steel,and the failure mechanism was stress/strain concentration,microstructure degradation and oxidation coupling acting on the *** numerical simulation results show that interface stress/strain concentration was due to the differences in coefficient of thermal expansion and creep strength,and the degree of stress/strain concentration was related to service *** ferrite band formed at the WM/ferritic steel interface was prone to cracking,attracting the fracture along the *** interface crack allowed oxidation to develop along the WM/ferritic steel *** long-term service,the interface stress/strain concentration,microstructure and oxidation all evolved,which synergistically promoted interface failure of ***,only under the long-term service of low stress conditions could trigger the interface failure of ***,long-term service would reduce the mechanical strength and plasticity of DMW.

关键词： Dissimilar metal weld Failure Interface Stress/strain concentration Microstructure Oxidation

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Zeolite-encaged gold catalysts for the oxidative condensation of furfural

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Frontiers of Chemical Science and Engineering 2024年第8期18卷 67-77页

作者： Weijie li Mingyang Gao Bin Qin xin Deng Landong li School of Materials Science and Engineering Nankai UniversityTianjin 300350China College of Chemistry Nankai UniversityTianjin 300071China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

The oxidative condensation between renewable furfural and fatty alcohols is a crucial avenue for producing high-quality liquid fuels and valuable furan *** selectivity control in this reaction process remains a significant ***,we report the strategy of confining well dispersed gold species within ZSM-5 structure to construct highly active Au@ZSM-5 zeolite catalysts for the oxidative condensation of *** results and spectroscopy analyses demonstrate the efficient encapsulation of isolated and cationic Au clusters in zeolite ***@ZSM-5(K)catalyst shows remarkable performance with 69.7%furfural conversion and 90.2%furan-2-acrolein selectivity as well as good recycle *** is revealed that the microstructure of ZSM-5 zeolite can significantly promote oxidative condensation activity through confinement *** work presents an explicit example of constructing zeolite encaged noble metal catalysts toward targeted chemical transformations.

关键词： zeolite encapsulation gold oxidative condensation furfural

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Controllable Synthesis,Polar Behavior and Photoelectric Properties of BiOCl Microplates

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Chinese Journal of Structural Chemistry 2022年第3期41卷 77-84,I0009页

作者： li li-xin CHEN Chen li Zi-Hao WANG Fei-Fei liU Yun YI Zhi-Guo Key Laboratory of Optoelectronic Material and Device Department of PhysicsShanghai Normal UniversityShanghai 200444China State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 201800China Research School of Chemistry The Australian National UniversityCanberraACT 2600Australia

Bismuth oxychloride(BiOCl)square microplates were prepared via a facile hydrothermal *** X-ray diffraction patterns of the samples reveal a tetragonal BiOCl phase,and the scanning electron microscopy images show plate-like structures with large lateral size of 3~6μm and thickness in the range of 100~300 *** effects of surfactant,reaction temperature and duration on the morphology of BiOCl powders are systematically *** polar behavior of a BiOCl single-crystalline microplate is examined by using piezoresponse force microscopy evidenced over 80 pm displacement under 40 V bias *** addition,the photoelectric performance of the BiOCl microplates is evaluated by using electrochemical workstation with three-electrode system,and large photocurrent densities(over 0.5μA/cm^(2))and fast photoresponse(0.7~1.1 s)are detected by applying both 365 nm monochromatic light and sunlight *** surface potential changes of BiOCl microplate under different light condition,characterized by in-situ Kelvin probe force microscopy,further verify the separation ability of the photo-induced charge *** findings would be beneficial for further design photocatalytic and piezocatalytic materials.

关键词： bismuth oxychloride photoelectric microplate hydrothermal method

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Preparation and Properties of High Hardness and Oxidation Resisting Coating Using Electric Arc Spray

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材料热处理学报 2004年第5B期25卷 984-987页

作者： liZhuo-xin CUIli WANGJiang-ping TANGChun-tian BeijingUniversityofTechnology Beijing100022

A coating with high hardness, wear and oxidation resistance was prepared by electric arc spray. The hardness, bonding strength, abrasive wear and values of porosity and oxidation resistance of the coating were investigated. The microstructures and function of Cr3C2 of the coating were analyzed. The results showed surface Rockness Hardness HR30 reached 72.5 and average bond strength reached 49.1Mpa. Also porosity value was less than 2%. In addition, it was found from the comparison between the coating and 45CT coating that, oxidation resistance of the coating was less than that of 45CT, but the abrasive wear of the coating was obvious better than that of 45CT.

关键词：硬度磨损性能高温氧化电弧喷镀

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Trend of ambient seismic noise attenuation tomography:Theory and applications

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Science China Earth Sciences 2024年第10期67卷 3326-3330页

作者： xin liU Zhanwen li Department of Earth Sciences University of Hong KongHong Kong 999077China

1. Introduction Ambient seismic noise is an approximately uniform wave field generated by persistent and high-energy noise sources such as Earth's inherent vibrations and oceanic noise propagating within Earth's interior and multiple scattering. This noise wave field is widely distributed in subsurface structure and carries information about mechanical and physicochemical property of fault fracture zones.

关键词： seismic Earth fault

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Leaching kinetics of fluorine during the aluminum removal from spent li-ion battery cathode materials

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Journal of Environmental Sciences 2024年第4期138卷 312-325页

作者： Shengjie li Jianxin Zhu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

The high content of aluminum(Al)impurity in the recycled cathode powder seriously affects the extraction efficiency of Nickel,Cobalt,Manganese,and lithium resources and the actual commercial value of recycled materials,so Al removal is crucially important to conform to the industrial standard of spent li-ion battery cathode *** this work,we systematically investigated the leaching process and optimum conditions associated with Al removal from the cathode powder materials collected in a wet cathode-powder peeling and recycling production line of spent li-ion batteries(liBs).Moreover,we specifically studied the leaching of fluorine(F)synergistically happened along with the removal process of Al,which was not concerned about in other studies,but one of the key factors affecting pollution prevention in the recovery *** mechanism of the whole process including the leaching of Al and F from the cathode powder was indicated by using NMR,FTIR,and XPS,and a defluoridation process was preliminarily investigated in this *** leaching kinetics of Al could be successfully described by the shrinking core model,controlled by the diffusion process and the activation energy was 11.14 kJ/***,the leaching of F was attributed to the dissolution of liPF6and decomposition of PVDF,and the kinetics associated was described by Avrami *** interaction of Al and F is advantageous to realize the defluoridation to some *** is expected that our investigation will provide theoretical support for the large-scale recycling of spent liBs.

关键词： Al removal F leaching Cathode powder Heating alkali leaching Leaching kinetics

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A Note on the 3-Edge-Connected Supereulerian Graphs

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Journal of Mathematical Research and Exposition 2010年第5期30卷 944-946页

作者： Xiao Min li Deng xin li School of Mathematics and Statistics Chongqing Technology and Business University Chongqing 400067 P. R. China

For two integers l ：〉 0 and k ≥ 0, define C（l, k） to be the family of 2-edge connected graphs such that a graph G ∈ C（l, k） if and only if for every bond S lohtain in E（G） with ｜S｜ ≤3, each component of G - S has order at least （｜V（G）｜ - k）/l. In this note we prove that if a 3- edge-connected simple graph G is in C（10, 3）, then G is supereulerian if and only if G cannot be contracted to the Petersen graph. Our result extends an earlier result in [Supereulerian graphs and Petersen graph. JCMCC 1991, 9： 79-89] by Chen.

关键词： supereulerian collapsible reduction 3-edge-connected.

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Dynamic motion of quadrupedal robots on challenging terrain:a kinodynamic optimization approach

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Frontiers of Mechanical Engineering 2024年第3期19卷 23-40页

作者： Qi li Lei DING xin LUO Engineering Research Center of Hubei Province for Clothing Information Wuhan 430200China School of Computer Science and Artificial Intelligence Wuhan Textile UniversityWuhan 430200China State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

The dynamic motion of quadrupedal robots on challenging terrain generally requires elaborate spatial–temporal kinodynamic motion planning and accurate control at higher refresh rate in comparison with regular ***,conventional quadrupedal robots usually generate relatively coarse planning and employ motion replanning or reactive strategies to handle terrain *** resultant complex and computation-intensive controller may lead to nonoptimal motions or the breaking of locomotion *** this paper,a kinodynamic optimization approach is *** generate long-horizon optimal predictions of the kinematic and dynamic behavior of the quadruped robot on challenging terrain,we formulate motion planning as an optimization problem;jointly treat the foot’s locations,contact forces,and torso motions as decision variables;combine smooth motion and minimal energy consumption as the objective function;and explicitly represent feasible foothold region and friction constraints based on terrain *** track the generated motions accurately and stably,we employ a whole-body controller to compute reference position and velocity commands,which are fed forward to joint controllers of the robot’s *** verify the effectiveness of the developed approach through simulation and on a physical quadruped robot *** show that the quadruped robot can successfully traverse a 30°slope and 43% of nominal leg length high step while maintaining the rhythm of dynamic trot gait.

关键词： quadrupedal robot kinodynamic planning nonlinear optimization challenging terrain whole-body control

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