检索结果-南通市图书馆

维普期刊数据库博看期刊

Hydrochloric acid recovery from rare earth chloride solutions by vacuum membrane distillation

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第3期25卷 287-292页

作者： TANG Jianjun ZHOU Kanggen school of Construction and Environmental Engineering Shenzhen Polytechnic Shenzhen 518055 China Metallurgical Separation Science and Engineering Lab Central South University Changsha 410083 China

The possibility of the recovery of hydrochloric acid from rare earth （RE） chloride solutions was first experimentally studied by batch vacuum membrane distillation （VMD）. The recovery by continuous VMD was also studied to devise methods that enabled the operation of VMD setup in a stable condition as well as to increase the membrane-operating life The results indicated that HCl separation with RE by VMD was possible, and the recovery ratio of 80% could be achieved by batch VMD. In continuous VMD, when the temperature of circular solutions, circular rate, and downstream pressure was 62-63℃, 5.4 cm/s, and 9.33 kPa, respectively, the HCl concentration in circular solutions and the processing capacity per membrane area were obtained. The mathematical results were in accordance with the experimental ones.

关键词： membrane separation hydrochloric acid recovery vacuum membrane distillation rare earth mathematical stimulation

锂金属负极固态电解质界面膜形成和生长机理的理论研究进展

在线全文

学校读者我要写书评

暂无评论

储能科学与技术 2024年第9期13卷 3150-3160页

作者：周国兵许审镇北京大学材料科学与工程学院北京100871 江西师范大学化学工程学院江西南昌330022

锂金属负极因其极高的理论比容量在锂离子电池领域引起了极大的关注,但其高反应活性会引发电解液组分发生一系列复杂的降解反应,并在电极表面生成固态电解质界面膜(SEI)。SEI钝化层一方面能抑制电解液持续损耗,另一方面也会显著影响电... 详细信息

锂金属负极因其极高的理论比容量在锂离子电池领域引起了极大的关注,但其高反应活性会引发电解液组分发生一系列复杂的降解反应,并在电极表面生成固态电解质界面膜(SEI)。SEI钝化层一方面能抑制电解液持续损耗,另一方面也会显著影响电池的循环性能。因此,从原子/分子层面阐明SEI形成和生长机理成为了近些年的研究重点和热点。本文综述了不同理论模拟方法在SEI结构、组分和生长过程的最新研究进展,介绍了经典分子动力学、反应力场分子动力学、第一性原理分子动力学、机器学习力场分子动力学以及动力学蒙特卡罗等模拟方法在SEI研究中的成功案例。讨论了现有理论计算方法在模拟SEI形成和生长机理方面的局限性,提出可结合机器学习和动力学蒙特卡罗方法来实现长时域SEI形成和生长过程模拟的技术方案展望。

关键词：固态电解质界面膜形成和生长机理分子动力学动力学蒙特卡罗机器学习

Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of shenzhen in summer and in winter

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2006年第5期49卷 466-474页

作者： NIU Yuwen1,2,HE Lingyan1,2,HU Min2,ZHANG Jing2 & ZHAO Yunliang2 1. shenzhen graduate school of Peking university,shenzhen 518055,china 2. State Joint Key Laboratory of Environmental Simulation and Pollution Control,College of Environmental Sciences,Peking university,Beijing 100871,china 1. shenzhen graduate school of Peking university Shenzhen 518055 China 2. State Joint Key Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences Peking University Beijing 100871 China

Two field measurements for atmospheric fine particles were conducted in Baoan district of shenzhen during the summer and winter in 2004. Totally 30 sets of 24 h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal varia- tions and secondary pollution characteristics of fine particles during the sampling periods were dis-cussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 35 μg·m-3 and 57 μg·m-3, respectively, and those in winter were 99 μg·m-3 and 135 μg·m-3, respec-tively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 137%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in shenzhen. During the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. During the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol compo-nents in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from South china Sea in summer, and the air quality was good. The prevailing wind in winter was from china's Mainland to the north, and the polluted air mass led to poor air quality.

关键词： PM2.5, mass concentration, secondary pollution, seasonal variation, shenzhen.

Categories and characteristics of urban villages by GIS-based analysis:A case study of the shenzhen Special Economic Zone

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第S1期53卷 150-157页

作者： TONG De1,FENG ChangChun2,LI GuiCai1 & CHEN Peng1,2 1S henzhen graduate school,Peking university,shenzhen 518055,china 2College of Urban and Environmental Science,Peking university,Beijing 100871,china 1. shenzhen graduate school Peking University Shenzhen 518055 China 2. College of Urban and Environmental Science Peking University Beijing 100871 China

Studies on the characteristics of urban villages have attracted much interest in urban ***,how to advance the development of further theoretical analysis and quantitative methodologies,especially in the era that GIS and digital-urban technologies develop rapidly and provide precious resources on spatial issues,has always been a heated debate and *** this paper,a mathematical model based on spatial analysis is introduced to deal with the categorization and characterization of urban villages.A total of 89 urban villages in the shenzhen Special Economic Zone(SEZ)are used in this case *** ArcGIS tools on buffer analysis,distance and density calculation,and socio-economic and spatial attributes conjunction,urban villages’31 spatial variables in 4 aspects—social,economic,locational,and physical—are extracted,and 6 principal factors are concluded by principal components analysis to indicate the spatial characteristic of urban *** on the 6 principal factors,6 types of urban villages,including rapidly sprawling,large,rapidly industrializing periphery,overcrowded,intensively mobile and economically backward,are divided through the Hierarchical Clustering ***,the spatial features and formation mechanisms of each type of urban villages are ***,the advantages and the shortcomings of the methodology for this specific application are also ***,several guidelines on urban village management and renewal are provided based on the result of type *** outcome of the paper depends on the informational and technological support from the development of digital-city management,and is able to in turn provide basis on monitoring and improving urban villages which can further digital urban framework.

关键词： urban villages GIS-based analysis principal component hierarchical cluster the shenzhen Special Economic Zone (SEZ)

Above-and belowground biomass in relation to envi- ronmental factors in temperate grasslands, Inner Mongolia

在线全文

学校读者我要写书评

暂无评论

Science china(Life Sciences) 2008年第3期51卷 263-270页

作者： MA WenHong1,2, YANG YuanHe1, HE JinSheng1, ZENG Hui1,2 & FANG JingYun1 1 Department of Ecology, College of Urban and Environmental Sciences, Peking university, Beijing 100871, china 2 school of Environment & Urban Study, Peking university shenzhen graduate school, shenzhen 518055, china 1. Department of Ecology College of Urban and Environmental Sciences Peking University Beijing 100871 China 2. school of Environment & Urban Study Peking University Shenzhen Graduate School Shenzhen 518055 China

Above- and belowground biomasses of grasslands are important parameters for characterizing re- gional and global carbon cycles in grassland ecosystems. Compared with the relatively detailed in- formation for aboveground biomass (AGB), belowground biomass (BGB) is poorly reported at the re- gional scales. The present study, based on a total of 113 sampling sites in temperate grassland of the Inner Mongolia, investigated regional distribution patterns of AGB, BGB, vertical distribution of roots, and their relationships with environmental factors. AGB and BGB increased from the southwest to the northeast of the study region. The largest biomass occurred in meadow steppe, with mean AGB and BGB of 196.7 and 1385.2 g/m2, respectively; while the lowest biomass occurred in desert steppe, with an AGB of 56.6 g/m2 and a BGB of 301.0 g/m2. In addition, about 47% of root biomass was distributed in the top 10 cm soil. Further statistical analysis indicated that precipitation was the primary determinant factor in shaping these distribution patterns. Vertical distribution of roots was significantly affected by precipitation, while the effects of soil texture and grassland types were weak.

关键词： temperate grasslands aboveground biomass (AGB) belowground biomass (BGB) spatial pattern vertical distribution precipitation

Dynamic and Seismic Property Experiments of High Damping Concrete and Its Frame Models

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(Materials Science) 2008年第1期23卷 1-6页

作者：欧进萍刘铁军 LI Jilong shenzhen graduate school of Harbin Institute of Technology Shenzhen 518055 China school of Civil ＆ Hydraulic Engineering Dalian University of Technology Dalian 116024 China school of Civil Engineering Harbin Institute of Technology Harbin 150006 China

The loss tangent and storage modulus of cement mortar containing treated silica fume and styrene-acrylic are measured. Shaking table tests on three groups of 1/4 models of high damping concrete frames are conducted to compare the effects of reducing vibration. A relationship between the viscosity coefficient of high damping concrete and the damping coefficient of structure is established by analyzing dynamic parameters like damping ratio and frequency, and comparing responses of relative displacement and absolute acceleration. Surface treatment of silica fume and styrene-acrylic emulsion prior to incorporation in a cement mortar increases the loss tangent of the resulting composite by 40-400% as compared to the cement mortar without any admixtures, and the damping ratio of the reinforced concrete is raised by 7%-9%. In addition, a theoretical method of determining the viscosity coefficient of the material on the basis of shaking table test results is put forward.

关键词： high damping concrete damping relationship seismic experiment surface modification viscosity coefficient

The Design and Its Application of Cross-Coupled Controller in X-Y Table

在线全文

学校读者我要写书评

暂无评论

武汉理工大学学报 2006年第S3期28卷 783-787页

作者： XI Lei~1 WANG Xin~2 ZHANG Yi~1 (1.Division of Control and Mechatronics Engineering,Harbin Institute of Technology shenzhen graduate,shenzhen 518055,china, 2.Division of Mechanical Engineering & Automation,Harbin Institute of Technology shenzhen graduate,shenzhen 518055,china) Division of Control and Mechatronics Engineering Harbin Institute of Technology Shenzhen GraduateShenzhen 518055China Division of Mechanical Engineering & Automation Harbin Institute of Technology Shenzhen GraduateShenzhen 518055China

In conventional cross-coupled controller design,the method usually ignored the inherent characteristic of time-vary- ing parameters and model uncertainties in *** this paper,a cross-coupled controller(CCC)using an H~∞control scheme has been proposed to reduce the contouring error for an X-Y ***,the proposed CCC design,which is a typical Multi- Input Multi-Output(MIMO)system with linear time varying(LTV)characteristics,has been verified as being internally stable. The simulations are carried on Matlab simulink to verify the proposed method,and the results showed that the proposed method can reduce the contouring error significantly compared with the conventional one.

关键词： motion control cross-coupled control contour error H∞control

A novel compact low-power direct conversion receiver for mobile UHF RFID reader

在线全文

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2012年第10期55卷 2226-2233页

作者： LIU Shan 1*,WANG Xin'An 1*,SHEN JinPeng 1,WANG Bo 1,YE Tao 2 & HUANG Ru 3 1 Key Laboratory of Integrated Microsystems,Peking university shenzhen graduate school,shenzhen 518055,china 2 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies,HongKong,china 3 Institute of Microelectronics,Peking university,Beijing 100871,china 1. Key Laboratory of Integrated Microsystems Peking University Shenzhen Graduate School Shenzhen 518055 China 2. Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies HongKong China 3. Institute of Microelectronics Peking University Beijing 100871 China

A novel direct conversion receiver with low cost and low power is implemented in a 0.18 μm 1P6M standard CMOS process for a Mobile UHF RFID reader.A highly linear active mixer with low flicker noise and low noise active load is *** efficient and low cost on-chip DC offset voltage canceling scheme is adopted with a high-input-impedance four-input OPAMP to buffer the output of the DC offset canceller(DCOC) *** receiver has a measured input 1 dB compression point of 2 dBm and a sensitivity of 72 dBm in the presence of the large leakage signal from the *** occupying a silicon area of 2.5 mm 2 and consuming 21 mA from a 1.8 V supply,the receiver makes the mobile UHF RFID reader to communicate with a transponder in a distance of 1 m conveniently.

关键词： direct conversion receiver mobile UHF RFID reader low power DCOC active mixer four-input OPAMP

Identification of secondary organic aerosols based on aerosol mass spectrometry

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

中国科学：化学英文版 2010年第12期53卷 2593-2599页

作者： HUANG XiaoFeng 1,ZHAO QianBiao 1,2,HE LingYan 1,HU Min 2,BIAN QiJing 3,XUE Lian 1 & ZHANG YuanHang 2 1 Key Laboratory for Urban Habitat Environmental Science and Technology school of Environment and Energy,Peking university shenzhen graduate school,shenzhen 518055,china 2 State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering,Peking university,Beijing 100871,china 3 Division of Environment,Hong Kong university of Science & Technology,Hong Kong,china 1. Key Laboratory for Urban Habitat Environmental Science and Technology school of Environment and Energy Peking University Shenzhen Graduate School Shenzhen 518055 China2. State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Beijing 100871 China3. Division of Environment Hong Kong University of Science & Technology Hong Kong China

Secondary organic aerosol (SOA) is one of the major components of aerosols in the atmosphere and has not been well understood so *** to the complex chemical composition of organic aerosols,the identification of SOA has been a hotspot and difficult issue in the field of aerosol *** study attempts to quantitatively identify SOA in winter of shenzhen based on positive matrix factorization (PMF) *** sources were resolved and SOA was identified subsequently according to the characteristic ion fragments measured by highly time-resolved aerosol mass spectrometer *** showed that in the winter of shenzhen the average SOA concentration was 9.41±6.33 g/m 3,accounting for 39.9±21.8% of the total organic *** with primary organic aerosol (POA),the SOA concentrations had no large variation,suggestive of characteristics of regional secondary *** ratio of SOA/BC had pronounced diurnal variation,similar to that of O x (O3+NO2),indicating SOA formation was significantly controlled by activity of photochemistry in the *** most effective period for SOA formation was from 9 am～3 pm since the SOA/BC ratio increased by 122% during this *** study provides a new technical method and a new idea for SOA investigation.

关键词： secondary organic aerosol aerosol mass spectrometry positive matrix factorization (PMF)