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Computation of Invariant Curves and Identifying the Type of Critical Point

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Journal of Systems Science & Complexity 2018年第6期31卷 1698-1708页

作者： ZHI Junhai chen yufu School of Mathematical Sciences University of Chinese Academy of Sciences

This paper considers two dimensional systems which have purely imaginary *** order to obtain more propositions of invariant curves,the authors transform the real systems into complex differential systems by using a suitable linear *** authors also propose an algorithm to compute exponential *** improved method of constructing integrating factor by using all invariant curves is presented and can be used in determining the type of the equilibrium points.

关键词： Complex differential system equilibrium point exponential factor invariant curve

FINDING THE TOPOLOGY OF IMPLICITLY DEFINED TWO ALGEBRAIC PLANE CURVES

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Journal of Systems Science & Complexity 2012年第2期25卷 362-374页

作者： Ben GAO yufu chen School of Mathematical Sciences Graduate University of Chinese Academy of Sciences

An algorithm is given for computing in a very efficient way the topology of two real algebraic plane curves defined *** authors preform a symbolic pre-processing that allows us later to execute all numerical computati... 详细信息

关键词： Algebraic curves cylindrical algebraic decomposition generic position subresultantssequence topology.

Loading capacity and emulsification phenomena of HREE extraction by dialkylphosphinic acids with different β,γ,δ-substituents

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Journal of Rare Earths 2024年第1期42卷 191-199,I0007页

作者： Junlian Wang Guodong Xu Wen Xu Jianguo Cui yufu chen Ziyong Chang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing100083China Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mines Beijing100083China State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization Baotou Research Institute of Rare EarthsBaotou014030China

The relationship between dialkylphosphinic acid structure and their loading capacity for HREEs and emulsification phenomena has rarely been *** this paper,we took Lu extraction as an example to study the effect of β,γ,δ-substituents of dialkylphosphinic acids on their loading capacity and anti-emulsification performance for *** discuss conveniently,the dialkylphosphinic acids were classified into two groups:β-substituent group(P208,INET-1,P218,USTB-1 and P227)and γ,δ-substituent group(P218,P2132 and Cyanex 272).For β-substituent group extractants,their loading capacities are in the order P208(299.7 mg/L)≈INET-1(299.5 mg/L)>P218(270.8 mg/L)>>USTB-1(163.1 mg/L)>P227(151.4 mg/L),while their anti-emulsification/gelation performances are just in the opposite order P227>USTB-1>P218>P208≈INET-1 under the studied *** γ,δ-substituent group extractants,their loading capacities are in the order P218(270.8 mg/L)>P2132(192.3 mg/L)>Cyanex272(131.7 mg/L),while the anti-emulsification performance of P218 is better than those of P2132 and Cyanex *** loading capacity data given in the parentheses are obtained through repeatedly extracting Lu from ~4×10^(-4)mol/L of Lu aqueous feed solution with initial pH of 2.40 by 0.01 mol/L extractant at phase ratio A/O of 1:1.

关键词： Heavy rare earth element Dialkylphosphinic acid Extraction Loading capacity Emulsification

Driving mechanisms of desertification process in the Horqin Sandy Land—a case study in Zhalute Banner,Inner Mongolia of China

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Frontiers of Environmental Science & Engineering 2008年第4期2卷 487-493页

作者： Haiping TANG yufu chen Xinyu LI College of Resources Science and Technology Key Laboratory of Environmental Change and Natural Disaster of the Ministry of EducationBeijing Normal UniversityBeijing 100875China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China Institute of Beijing Landscape Gardening Beijing 100102China

Both natural and human factors contributing to desertification were examined to understand the driving mechanisms of the desertification process in Zhalute Banner,Inner Mongolia of *** coefficient of variation(CV)and climate departure index(Z)were calculated to examine the fluctuations and trends of interannual variations of temperature and precipitation;TM remote sensing data was extracted to obtain the sandy land area;linear regression analysis was used to analyze climate changes and the socio-economic evolution over the years,and it was also used to standardize the variables,which included annual temperature,annual precipitation,human population,and livestock number,in order to measure the difference in the rate of change between climate and anthropogenic *** results showed that there was a rise of about 1.6uC in temperature but no significant change in precipitation from 1961 to 2000,which indicated a short-term climatic trend toward aridity in this area,a condition necessary for *** fraction of precipitation in spring tended to increase whilst the fraction in autumn and winter *** the human population and livestock population had tripled and the cultivated area had doubled from 1961 to 2000,suggesting that socio-economic factors might have contributed more significantly to the *** 1988 and 1997,the sandy land area increased by 12.5%,nearly 2.4 times in the farming *** could be concluded that the driving mechanisms of the desertification processes in Zhalute banner are mainly the policy of cropland expansion and the rising populations of humans and their livestock,which has affected the land use pattern in the past decades.

关键词： climatic change potential evapo-transpiration(PE) human activities land use change

The role ofβ,γ,δ-substituent of dialkylphosphinic acids in HREE extraction and separation behaviors

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Journal of Rare Earths 2023年第11期41卷 1789-1795,I0005页

作者： Junlian Wang Wen Xu Jianguo Cui Guodong Xu yufu chen Peilong Wang Ziyong Chang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing100083China State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization Baotou Research Institute of Rare EarthsBaotou014030China Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mines Beijing100083China

Heavy rare earth element(HREE)separation has always been a great *** kind of dialkylphosphinic acids is recognized as the third generation of organophosphorous acid ***,detailed relationship betweenβ-substituent(especially when it changes from H to methyl,and further to ethyl)and their extraction behaviors and selectivity for HREEs have rarely been ***,there are also few reports on effect ofγ,δ-substituent on HREE extraction and *** this paper,we synthesized five and collected two dialkylphosphinic acids with differentβ,γ,δ-substituents(from H to ethyl).These extractants were divided into two groups to discuss their extraction behaviors and selectivity for HREEs:β-substituent group(P208,INET-1,P218,USTB-1 and P227)andγ,δ-substituent group(P218,P2132 and Cyanex 272).To evaluate and compare their extractabilities,P507 was used as a reference and Tm,Yb,Lu were extracted with 0.01 mol/L of these extractants from single Tm,Yb and Lu solutions(~4×10^(-4)mol/L)at different initial ***,pH_(0.5)(Tm),pH_(0.5)^(Yb)and pH_(0.5)^(Lu)values and their differences(ΔpH_(0.5)^(Tm-Yb),ΔpH_(0.5)^(Yb-Lu),ΔpH_(0.5)^(Tm-Lu))for each extractant were given to roughly evaluate their separation performance for Tm,Yb and *** further investigate the selectivity of these extractants for HREEs,Tb,Dy,Ho,Er,Tm,Yb and Lu were extracted from their mixed solution with initial pH of 4.00 at phase ratio A/O of 2:1,1:1 or 1:*** HREE separation performance is mainly discussed based on the adjacent HREE separation factors(β_(N+1/N))and their average value(β_(Tb-Lu)).

关键词： Heavy rare earth element Extraction Separation Dialkylphosphinic acid Substituent effect

Microinterface intensification in hydrogenation and air oxidation processes

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Chinese Journal of Chemical Engineering 2022年第10期50卷 292-300页

作者： Hongliang Qian Hongzhou Tian Guoqiang Yang Gaodong Yang Lei Li Feng Zhang Zheng Zhou Weihua Huang yufu chen Zhibing Zhang School of Chemistry&Chemical Engineering Nanjing UniversityNanjing 210046China Department of Pharmaceutical Engineering China Pharmaceutical UniversityNanjing 211198China Nanjing Institute of Microinterfacial Reaction Engineering Nanjing 210008China

Hydrogenations and air oxidations usually have low apparent reaction rate,generally controlled by mass transfer rate,and widely exist in the modern chemical manufacturing *** key to increase the mass transfer rate is the reduction of the liquid film resistance 1/*** this work,the original concept of microinterface intensification for mass transfer and then for these reactions has been *** derived the regulation model and set up the mathematical calculation method of micron-scale gas-liquid interface structure on mass transfer and reaction,designed the mechanical energy exchange device that can produce gas-liquid microinterface system on a large scale,and established the OMIS system which is able on line to measure the diameter and distribution of millions of microbubbles,interface area a and mass transfer film thicknessδM,as well as developed a series of microinterface intensified reactor systems(MIRs)for the applications of hydrogenation and air oxidation *** is believed that this research will provide an up-to-date development for the intensification of hydrogenation and air oxidation reactions.

关键词： Hydrogenation andoxidation Microinterface intensification Mass transfercoefficient Structure-effect regulation Online measurement

Design Methods of Ecological Urban Park

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Journal of Landscape Research 2013年第Z3期5卷 1-3,7页

作者： chen yufu Architectural and Planning College Jilin Jianzhu University

On the basis of summarizing design methods of ecological urban park,it was proposed that preparatory control work should be enhanced,reasonable zoning of use functions and spatial structures established,overall consideration given to traffi c system and vertical design,and landscaping system created based on ecological view. In addition,it was also signifi cant for designers and management departments taking proper planning and designs to create new urban open spaces,improve supporting facilities,enhance public participation mechanism,and keep pace with the sustainable development of the city.

关键词： Ecological Urban park Design method

Rural Poverty Patterns and Influencing Factors in Yunnan Province,China:Based on County Level Dataset

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Journal of Resources and Ecology 2020年第4期11卷 366-377页

作者： SHANG Xiaowen chen yufu Institute of Geographic Sciences and Nature Resources Research Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

The identification of poverty at the county level is the precondition for poverty alleviation by formulating accurate strategies that are targeted for a certain *** Province has the largest number of poverty counties in *** vast number of people living under the poverty-line,and the deep degree of poverty across a wide distribution range,pose major *** on the rural poverty incidence data,this paper describes the rural poverty patterns in Yunnan Province in 2010 and 2015,and then it explores the main factors which influence the incidence and changes in rural poverty at the county level in Yunnan Province using a stepwise regression analysis *** study found that the rural poverty in counties of Yunnan Province was deeply affected by natural conditions and the geographical *** 2010 and 2015,the rural poverty situation in the middle region of Yunnan Province was relatively light,while it was more serious in the northwest,northeast and south *** pattern of county poverty is in good agreement with the topography and landforms of Yunnan Province and the poverty-stricken *** are strong correlations between the incidence of rural poverty in Yunnan Province with both the annual per capita net income of rural residents and the degree of agricultural *** factors are related to the living standards and agricultural production necessary for the peasantry to sustain their *** change in the incidence of rural poverty at the county level in Yunnan Province from 2010 to 2015 is significantly correlated with changes in the value-added of the primary industries and the degree of agricultural *** correlations indicate that the development of primary industry plays a key role in the process of lifting rural residents in Yunnan Province out of poverty so they can achieve ***,improving the annual per capita net income of rural residents and the degree of agricultural me

关键词： rural poverty poverty incidence stepwise regression analysis Yunnan Province

Progress of research on urban-rural transformation and rural development in China in the past decade and future prospects

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Journal of Geographical Sciences 2016年第8期26卷 1117-1132页

作者： LIU Yansui LONG Hualou chen yufu WANG Jieyong LI Yurui LIYuheng YANG Yuanyuan ZHOU Yang Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Academy of Land and Urban-Rural Development Beijing Normal University Beijing 100875 China

Urban-rural transformation and rural development are issues at the forefront of research on the topic of the urban-rural relationship in the field of geography, as well as important practical problems facing China＇s new urbanization and overall planning of urban and rural development. The Center for Regional Agricultural and Rural Development, part of the Institute of Geographic Sciences and Natural Resources Research under the Chinese Academy of Sciences, was established in 2005. The Center has laid solid foundations for integrating research in the areas of agricultural geography and rural development in China over the past decade. The paper aims to review the major achievements in rural geographical research in China during the past decade, analyze innovative developments in relevant theories and methods, and suggest prospects and countermeasures for promoting comprehensive studies of urban-rural transformation and rural geography. The research shows that innovative achievements have been made in rural geography studies of China in the past decade as major national policy development, outputs of result and decision making support; new breakthroughs have been achieved in such major research projects as geographical integrated theory, land remediation projects and technology demonstration projects, new urbanization and urban-rural integration; significant progress has been made in actively expanding the frontiers of rural geography and pushing forward theoretical innovations in land and resource projects; and, with China＇s development goals of building a moderately prosperous society in all respects and achieving modernization in mind, future innovative developments in agricultural and rural geography should aim to make research more strategic, systematic, scientific and security-oriented, with attention given to promoting systematic scientific research on international cooperation and global rural geography.

关键词： urban-rural transformation rural development rural geographical projects urbanization China