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Molecular dynamics study on microscale residual stress of graphene/aluminum nanocomposites by selective laser sintering

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Rare Metals 2022年第11期41卷 3677-3683页

作者： xing-Nan Hao Xia liu Department of Engineering Mechanics Beijing University of TechnologyBeijing100124China

The fabrication of graphene/metal matrix composites by selective laser sintering(SLS)technique has been extensively studied;however,the complex micros truc ture and residual stress limit their further ***,the sinterin... 详细信息

关键词： stress residual composites

Mathematical Simulation and Design of Three-Phase Bubble Column Reactor for Direct Synthesis of Dimethyl Ether from Syngas

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Journal of Natural Gas Chemistry 2007年第2期16卷 193-199页

作者： Dianhua liu xing Hua Dingye Fang College of Chemical Engineering East China University of Science and Technology Shanghai 200237 China

A three-phase reactor mathematical model was set up to simulate and design a three-phase bubble column reactor for direct synthesis of dimethyl ether （DME） from syngas, considering both the influence of part inert carrier backmixing on transfer and the influence of catalyst grain sedimentation on reaction. On the basis of this model, the influences of the size and reaction conditions of a 100000 t/a DME reactor on capacity were investigated. The optimized size of the 10000 t/a DME synthesis reactor was proposed as follows： diameter 3.2 m, height 20 m, built-in 400 tube heat exchanger （Ф 38×2 mm）, and inert heat carrier paraffin oil 68 t and catalyst 34.46 t. Reaction temperature and pressure were important factors influencing the reaction conversion for different size reactors. Under the condition of uniform catalyst concentration distribution, higher pressure and temperature were proposed to achieve a higher production capacity of DME. The best ratio of fresh syngas for DME synthesis was 2.04.

关键词： dimethyl ether syngas three-phase reactor DME synthesis slurry bed mathematical simulation model

Social media and mobility landscape:Uncovering spatial patterns of urban human mobility with multi source data

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Frontiers of Environmental Science & Engineering 2018年第5期12卷 101-114页

作者： Yilan Cui xing Xie Yi liu School of Environment Tsinghua UniversityBeijing 100084China Microsoft Research Asia Microsoft CorporationBeijing 100080China

In this paper,we present a three-step methodological framework,including location identification,bias modification,and out-of-sample validation,so as to promote human mobility analysis with social media *** specifically,we propose ways of identifying personal activity-specific places and commuting patterns in Beijing,China,based on Weibo(China’s Twitter)check-in records,as well as modifying sample bias of check-in data with population synthesis *** independent citywide travel logistic survey is used as the benchmark for validating the *** differences are discerned from Weibo users’and survey respondents’activity-mobility patterns,while there is a large variation of population representativeness between data from the two *** bias modification,the similarity coefficient between commuting distance distributions of Weibo data and survey observations increases substantially from 23% to 63%.Synthetic data proves to be a satisfactory costeffective alternative source of mobility *** proposed framework can inform many applications related to human mobility,ranging from transportation,through urban planning to transport emission modeling.

关键词： Social media Human mobility Population bias Sample reconstruction Data integration

Synthesis of uniform hexagonal Ag nanoprisms with controlled thickness and tunable surface plasmon bands

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International Journal of Minerals,Metallurgy and Materials 2019年第6期26卷 796-802页

作者： xing Chen Xun liu Kai Huang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Lab of Green Recycling and Extraction of Metals University of Science and Technology BeijingBeijing 100083China

In this work,we synthesized monodispersed hexagonal Ag nanoprisms in high yields in a system of poly(vinylpyrrolidone)(PVP)in N-methylpyrrolidone(NMP).A blue shift occurred and was strongly dependent on the thickness of the uniform Ag nanoprisms,which had almost the same radial *** the Ag nanoprisms grew thicker,their in-plane dipole resonance peaks markedly shifted toward shorter wavelengths(i.e.,blue shift).PVP played a critical role of favoring vertical growth of the Ag nanoplates,preventing aggregation,and inducing the formation of Ag hexagonal nanoprisms(HNPs)through the transformation from thin Ag triangular nanoprisms(TNPs).Compared with similar previous research,the present study provides quite uniform Ag hexagonal nanoplates,which makes the blue shift related more solely and distinctly to the thickness of the Ag *** findings of this work provide a new perspective toward understanding the unique optical characteristics of Ag HNPs with different aspect ratios.

关键词： hexagonal nanoprisms silver nanoprisms blue shift thickness effect

Facile synthesis of flake-like dihydrate zinc oxalate particles

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International Journal of Minerals,Metallurgy and Materials 2019年第2期26卷 234-240页

作者： xing Chen Xin liu Kai Huang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Global Energy Research Institute Future Science and Technology Park Beijing Key Lab of Green Recycling and Extraction of Metals University of Science and Technology Beijing

Monodispersed dihydrated zinc oxalate(ZnC_2O_4·2H_2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO_3)_2) and sodium oxalate(Na_2C_2O_4) in the presence of a citrate ligand, with an average flat size of approximately 10–15 μm. The important parameters, including the solution pH values and the concentration of the zinc ions and citrate ligand, were investigated using a series of experiments. It is verified that the citrate ligand significantly affects the morphology of zinc oxalate particles, probably via its multiple roles of chelating, dispersing, and selective absorption. Thermodynamic equilibrium of the distribution of zinc species in an aqueous solution of Zn(Ⅱ)-citrate-oxalate-H_2O was estimated to explain the experimental results and to clarify the size and morphological evolution mechanism of the precipitated particles.

关键词： facile synthesis zinc oxalate flaky morphology citrate ligand one-pot synthesis

Cloud detection from visual band of satellite image based on variance of fractal dimension

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Journal of Systems Engineering and Electronics 2019年第3期30卷 485-491页

作者： TIAN Pingfang GUANG Qiang liu xing School of Computer Science and Technology Wuhan University of Science and Technology Wuhan 430065 China Key Laboratory of Intelligent Information Processing and Real-Time Industrial System in Hubei Province Wuhan 430065 China Institute of Big Data Science and Engineering Wuhan University of Science and Technology Wuhan 430065 China Key Laboratory of Rich-Media Knowledge Organization and Service of Digital Publishing Content National Press and Publication Administration Beijing 100038 China

Cover ratio of cloud is a very important factor which affects the quality of a satellite image, therefore cloud detection from satellite images is a necessary step in assessing the image quality. The study on cloud detection from the visual band of a satellite image is developed. Firstly, we consider the differences between the cloud and ground including high grey level, good continuity of grey level, area of cloud region, and the variance of local fractal dimension (VLFD) of the cloud region. A single cloud region detection method is proposed. Secondly, by introducing a reference satellite image and by comparing the variance in the dimensions corresponding to the reference and the tested images, a method that detects multiple cloud regions and determines whether or not the cloud exists in an image is described. By using several Ikonos images, the performance of the proposed method is demonstrated.

关键词： cloud detection visual image satellite image variance of local fractal dimension (VLFD)

Segmented tubular synthesis of monodispersed microsized copper oxalate

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International Journal of Minerals,Metallurgy and Materials 2019年第4期26卷 460-466页

作者： Xun liu xing Chen Kai Huang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing Key Lab of Green Recycling and Extraction of Metals University of Science and Technology Beijing

Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, residence time, and segmented media on the final products were investigated experimentally. The obtained copper oxalate microsized particles were disc-like in the presence of citrate ligand,which was the shape inducer for the precipitated copper oxalate. Thermodynamic equilibrium diagrams of the Cu(Ⅱ)-oxalate-H_2O,Cu(Ⅱ)-oxalate-citrate-H_2O, and Cu(Ⅱ)-oxalate-EDTA-H_2O solution systems were drawn to estimate the possible copper species under the experimental conditions and to explain the formation mechanisms of copper oxalate particles in the segmented fluidic reactor. Both theoretical and experimental results indicated that the presence of chelating reagents such as citrate and EDTA had distinct effect on the evolution of particle shape. Air and kerosene were tested as media for the fluidic flow segmentation, and the latter was verified to better promote the growth of copper oxalate particles. The present study provides an easy method to prepare monodispersed copper oxalate microsized particles in a continuous scaling-up way, which can be utilized to prepare the precursor material for conductive inks.

关键词： segmented flow tube reactor copper oxalate powder monodispersed scaling-up shape inducer

Progress of environmental research in China from 2000 to 2019: Case studies of JES and ES&T

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Journal of Environmental Sciences 2022年第6期34卷 139-141页

作者： Rongrong Lei Ying xing Wenbin liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Institutes of Science and Development Chinese Academy of SciencesBeijing 100190China Hangzhou Institute For Advanced Study UCASHangzhou 310024China

China’s tremendous economic and cultural progress since the initiation of the reforms and opening up process has been accompanied by the steady expansion of its scientific research *** selected Journal of Environmental Sciences and Environmental Science&Technology(hereinafter referred to as JES and ES&T,respectively)as two representative journals for assessing the progress and impact of research in the field of environmental science in China.

关键词： reforms tremendous assessing

Graphene-anchored sodium single atoms:A highly active and stable catalyst for transesterification reaction

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Nano Research 2024年第6期17卷 4979-4985页

作者： Song-Song Peng Yao Nian xing-Ru Song Xiang-Bin Shao Chen Gu Zhi-Wei xing Shi-Chao Qi Peng Tan you Han Xiao-Qin liu Lin-Bing Sun State Key Laboratory of Materials-Oriented Chemical Engineering Jiangsu National Synergetic Innovation Center for Advanced Materials(SICAM)College of Chemical EngineeringNanjing Tech University30 South Puzhu RoadNanjing 211816China School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Solid strong base catalysts have received considerable attention in various organic reactions due to their facile separation,neglectable corrosion,and environmental *** great progress has been made in the preparation of solid strong base catalysts,it is still challenging to avoid basic sites aggregation on support and active sites loss in reaction ***,we report a tandem redox strategy to prepare Na single atoms on graphene,producing a new kind of solid strong base catalyst(Na1/G).The base precursor NaNO_(3)was first reduced to Na2O by graphene(400℃)and successively to single atoms Na anchored on the graphene vacancies(800℃).Owing to the atomically dispersed of basicity,the resultant catalyst presents high activity toward the transesterification of methanol and ethylene carbonate to synthesize dimethyl carbonate(turnover frequency(TOF)value:125.7 h^(−1)),which is much better than the conventional counterpart Na2O/G and various reported solid strong bases(TOF:1.0-90.1 h^(−1)).Furthermore,thanks to the basicity anchored on graphene,the Na1/G catalyst shows excellent durability during *** work may provide a new direction for the development of solid strong base catalysts.

关键词： solid strong base catalyst basic sites redox graphene single Na atoms