Monitoring the service condition of concrete structures requires the quantitative assessment of properties and corrosion rate of structural steels surrounded by concrete.A multi-cell sensor system that included a refe...Monitoring the service condition of concrete structures requires the quantitative assessment of properties and corrosion rate of structural steels surrounded by concrete.A multi-cell sensor system that included a reference electrode,a chloride content sensor,a macrocell current unit and an electrical resistance measurement unit was developed.This system provided the following important electrochemical data in the cover-zone concrete on site:open circuit potential,macrocell current from anodes to cathode,chloride profile,concrete resistance and corrosion rate of built-in anodes.The experimental results show that the macrocell current increases when the chloride content in concrete is higher.Thus,monitoring the chloride content is a good method for monitoring the corrosion state.The chloride ion content and cover depth are the key factors that affect the electrical resistance of concrete.Without considering the temperature and time,a simplified model of the instantaneous corrosion rate of steel rebar in a concrete structure based on the measured chloride contents and concrete resistance was proposed.The test results further prove the reliability of this simplified predicting model.展开更多
Reduction of Cr(VI)using zero-valent iron(ZVI)could not only decrease the amounts of chemicals used for reduction,but also decrease the discharge of sludge.In order to find a desirable ZVI material,reduction of Cr(VI)...Reduction of Cr(VI)using zero-valent iron(ZVI)could not only decrease the amounts of chemicals used for reduction,but also decrease the discharge of sludge.In order to find a desirable ZVI material,reduction of Cr(VI)with a relative high concentration using different kinds of ZVI powders(mainly carbon differences)including reduced Fe,grey cast iron,pig iron,nodular pig iron was carried out.Parameters such as ZVI dosage,type and size affecting on Cr(VI)reduction were firstly examined and grey cast iron was selected as a preferable reducing material,followed by pig iron.Additionally,it was found that the parameters had significant influences on experimental kinetics.Then,morphology and composition of the sample before and after reaction were characterized by SEM,EPMA and XPS analyses to disclose carbon effect on the reducibility.In order to further interpret reaction mechanism,different reaction models were constructed.It was revealed that not only the carbon content could affect the Cr(VI)reduction,but also the carbon structure had an important effect on its reduction.展开更多
The observations of Global Positioning System(GPS) scintillation,Total Electron Content(TEC)depletion,the periodic structure of TEC and Rate of TEC Index(ROTI) over south China were presented.Data were collected from ...The observations of Global Positioning System(GPS) scintillation,Total Electron Content(TEC)depletion,the periodic structure of TEC and Rate of TEC Index(ROTI) over south China were presented.Data were collected from GPS observations at stations of Shenzhen and Guangzhou from 2011 to 2012.This study reported that the ratio of simultaneous occurrences of TEC depletions with strong scintillations was higher than that of TEC depletions with weak scintillations in vernal and autumnal equinoxes of 2011 over South China.The number of the periodic structures of TEC with depletion contained was greater than that with no depletion contained corresponding to strong scintillations.The structure of the slab of plasma irregularities could be responsible for the simultaneous occurrences of TEC depletion with strong scintillations and ROTI.Before and during the occurrences of strong scintillation,there was Large-Scale Wave Structure(LSWS) which provided the seed ionization perturbation to trigger ESF irregularities and contributed to the periodic structure of TEC.展开更多
The formation of plasma bullets’ring-shaped structure in atmospheric pressure helium is analyzed by using a coupled fluid model.The model consists of a two-dimension neutral gas flow module and a one-dimension plasma...The formation of plasma bullets’ring-shaped structure in atmospheric pressure helium is analyzed by using a coupled fluid model.The model consists of a two-dimension neutral gas flow module and a one-dimension plasma dynamics module.The obtained radial distributions of the electron’s number density and the nitrogen’s metastable number density have different structures under different types of reactions or air contents in the model.It shows that total electron impact ionization plays an important role in sustaining the discharge,and together with Penning process,they lead to the shifted-off structure of electron number density.Meanwhile,the ring structure of plasma bullets forms mainly due to the excitation reaction of nitrogen molecule on air contents.展开更多
为了探究轮作种植模式对植烟土壤理化和生物学特性及烟叶化学成分影响,揭示影响烟叶化学品质的关键因子,在Web of Science、Springer、中国知网、万方、维普和Google Scholar等中英文数据库,以长期定位试验、烟草轮作、土壤理化性质、...为了探究轮作种植模式对植烟土壤理化和生物学特性及烟叶化学成分影响,揭示影响烟叶化学品质的关键因子,在Web of Science、Springer、中国知网、万方、维普和Google Scholar等中英文数据库,以长期定位试验、烟草轮作、土壤理化性质、土壤微生物和烟叶化学成分为关键词,筛选代表性文章51篇,涉及轮作试验194个,非轮作对照试验51个,提取有效田间数据1008组,通过Meta分析、Pearson相关性分析和结构方程模型分析,揭示轮作对烟叶化学成分的影响因素。Meta分析结果表明,不同科类作物与烟草轮作显著改善土壤物理性质、化学性质和生物学特性等质量指标及提高烟叶钾(42.46%)、糖碱比(40.86%)、烟碱(38.59%)、还原糖(38.59%)和总糖(38.51%)等化学成分指标(P<0.05),使各成分更加协调,其中,以烤烟-禾本科轮作模式的效果最好;化学成分含量还受年均温度、年降水量和土壤类型等因素的影响。Pearson相关性分析结果表明,土壤碱解氮(1:R^(2)=0.4468,2:R^(2)=0.4673)、有机质含量(1:R^(2)=0.5089,2:R^(2)=0.3674)、酸性磷酸酶活性(1:R^(2)=0.3161,2:R^(2)=0.3850)和微生物Ace指数(1:R^(2)=0.2026,2:R^(2)=0.2660)与烟叶糖碱比(1:R^(2))和钾含量(2:R^(2))呈显著正相关(P<0.05)。结构方程模型分析表明,土壤有机质和碱解氮含量是影响烟叶钾含量的主要因素,微生物Ace指数和碱解氮含量是影响糖碱比的主要因素。轮作模式对烟草叶片化学成分有显著影响。具体而言,禾本科-烟草轮作模式对土壤的物理、化学和生物特性以及烟叶的化学成分都有积极的影响。Meta分析、Pearson相关分析和结构方程模型进一步证实了这些发现。基于这些结果,建议实施禾本科和烟草轮作制度,以提高烟草生产的质量和效率。该系统应综合考虑年均降水量、年均气温和土壤质量指标,优化烟草生长条件。通过调整轮作制度和土壤管理方法,农民可以在保持烟草质量的同时获得更高的产量,从而提高工业产量和效率。展开更多
基金Project(200632800003-11) supported by Western Communications Construction Scientific and Technological Project in China
文摘Monitoring the service condition of concrete structures requires the quantitative assessment of properties and corrosion rate of structural steels surrounded by concrete.A multi-cell sensor system that included a reference electrode,a chloride content sensor,a macrocell current unit and an electrical resistance measurement unit was developed.This system provided the following important electrochemical data in the cover-zone concrete on site:open circuit potential,macrocell current from anodes to cathode,chloride profile,concrete resistance and corrosion rate of built-in anodes.The experimental results show that the macrocell current increases when the chloride content in concrete is higher.Thus,monitoring the chloride content is a good method for monitoring the corrosion state.The chloride ion content and cover depth are the key factors that affect the electrical resistance of concrete.Without considering the temperature and time,a simplified model of the instantaneous corrosion rate of steel rebar in a concrete structure based on the measured chloride contents and concrete resistance was proposed.The test results further prove the reliability of this simplified predicting model.
基金Project(51604131)supported by the National Natural Science Foundation of ChinaProject(2017FB084)supported by the Yunnan Province Applied Basic Research,China+1 种基金Project(KKSY201563041)supported by the Talent&Training Program of Yunnan Province,ChinaProjects(2017T20090159,2018T20150055)supported by the Testing and Analyzing Funds of Kunming University of Science and Technology,China
文摘Reduction of Cr(VI)using zero-valent iron(ZVI)could not only decrease the amounts of chemicals used for reduction,but also decrease the discharge of sludge.In order to find a desirable ZVI material,reduction of Cr(VI)with a relative high concentration using different kinds of ZVI powders(mainly carbon differences)including reduced Fe,grey cast iron,pig iron,nodular pig iron was carried out.Parameters such as ZVI dosage,type and size affecting on Cr(VI)reduction were firstly examined and grey cast iron was selected as a preferable reducing material,followed by pig iron.Additionally,it was found that the parameters had significant influences on experimental kinetics.Then,morphology and composition of the sample before and after reaction were characterized by SEM,EPMA and XPS analyses to disclose carbon effect on the reducibility.In order to further interpret reaction mechanism,different reaction models were constructed.It was revealed that not only the carbon content could affect the Cr(VI)reduction,but also the carbon structure had an important effect on its reduction.
基金Supported by the National Natural Science Young Foundation of China(41704168)。
文摘The observations of Global Positioning System(GPS) scintillation,Total Electron Content(TEC)depletion,the periodic structure of TEC and Rate of TEC Index(ROTI) over south China were presented.Data were collected from GPS observations at stations of Shenzhen and Guangzhou from 2011 to 2012.This study reported that the ratio of simultaneous occurrences of TEC depletions with strong scintillations was higher than that of TEC depletions with weak scintillations in vernal and autumnal equinoxes of 2011 over South China.The number of the periodic structures of TEC with depletion contained was greater than that with no depletion contained corresponding to strong scintillations.The structure of the slab of plasma irregularities could be responsible for the simultaneous occurrences of TEC depletion with strong scintillations and ROTI.Before and during the occurrences of strong scintillation,there was Large-Scale Wave Structure(LSWS) which provided the seed ionization perturbation to trigger ESF irregularities and contributed to the periodic structure of TEC.
基金Project supported by National Natural Science Foundation of China （10775026 11275042）, Hebei Provincial Natural Science Foundation of China （A2012201015）.
文摘The formation of plasma bullets’ring-shaped structure in atmospheric pressure helium is analyzed by using a coupled fluid model.The model consists of a two-dimension neutral gas flow module and a one-dimension plasma dynamics module.The obtained radial distributions of the electron’s number density and the nitrogen’s metastable number density have different structures under different types of reactions or air contents in the model.It shows that total electron impact ionization plays an important role in sustaining the discharge,and together with Penning process,they lead to the shifted-off structure of electron number density.Meanwhile,the ring structure of plasma bullets forms mainly due to the excitation reaction of nitrogen molecule on air contents.
文摘为了探究轮作种植模式对植烟土壤理化和生物学特性及烟叶化学成分影响,揭示影响烟叶化学品质的关键因子,在Web of Science、Springer、中国知网、万方、维普和Google Scholar等中英文数据库,以长期定位试验、烟草轮作、土壤理化性质、土壤微生物和烟叶化学成分为关键词,筛选代表性文章51篇,涉及轮作试验194个,非轮作对照试验51个,提取有效田间数据1008组,通过Meta分析、Pearson相关性分析和结构方程模型分析,揭示轮作对烟叶化学成分的影响因素。Meta分析结果表明,不同科类作物与烟草轮作显著改善土壤物理性质、化学性质和生物学特性等质量指标及提高烟叶钾(42.46%)、糖碱比(40.86%)、烟碱(38.59%)、还原糖(38.59%)和总糖(38.51%)等化学成分指标(P<0.05),使各成分更加协调,其中,以烤烟-禾本科轮作模式的效果最好;化学成分含量还受年均温度、年降水量和土壤类型等因素的影响。Pearson相关性分析结果表明,土壤碱解氮(1:R^(2)=0.4468,2:R^(2)=0.4673)、有机质含量(1:R^(2)=0.5089,2:R^(2)=0.3674)、酸性磷酸酶活性(1:R^(2)=0.3161,2:R^(2)=0.3850)和微生物Ace指数(1:R^(2)=0.2026,2:R^(2)=0.2660)与烟叶糖碱比(1:R^(2))和钾含量(2:R^(2))呈显著正相关(P<0.05)。结构方程模型分析表明,土壤有机质和碱解氮含量是影响烟叶钾含量的主要因素,微生物Ace指数和碱解氮含量是影响糖碱比的主要因素。轮作模式对烟草叶片化学成分有显著影响。具体而言,禾本科-烟草轮作模式对土壤的物理、化学和生物特性以及烟叶的化学成分都有积极的影响。Meta分析、Pearson相关分析和结构方程模型进一步证实了这些发现。基于这些结果,建议实施禾本科和烟草轮作制度,以提高烟草生产的质量和效率。该系统应综合考虑年均降水量、年均气温和土壤质量指标,优化烟草生长条件。通过调整轮作制度和土壤管理方法,农民可以在保持烟草质量的同时获得更高的产量,从而提高工业产量和效率。
