检索结果-南通市图书馆

An improved GC-ECD method for measuring atmospheric N_2O

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2013年第3期25卷 547-553页

作者： Yuanyuan Zhang Yujing Mu Shuangxi Fang junfeng liu Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Key Laboratory for Atmospheric Chemistry Centre for Atmosphere Watch and ServicesChinese Academy of Meteorological Sciences

Gas chromatography equipped with an electron capture detector （GC-ECD） has been widely used for measuring atmospheric N2O,but nonlinear response and the influence of atmospheric CO2 have been recognized as defects for *** original GCECD method using N 2 as carrier gas was improved by introducing a small flow rate of CO2 makeup gas into the ECD,which could well remedy the above *** N2O signal of the improved method was 4-fold higher than that of the original method and the relative standard deviation was reduced from 〉 1% to 0.31%.N2O concentrations with different CO2 concentrations （172.2×10-6-1722×10-6mol/mol） measured by the improved GC-ECD method were in line with the actual N2O ***,the N2O concentrations detected by the original method were largely biased with a variation range of-4.5%～7%.The N2O fluxes between an agricultural field and the atmosphere measured by the original method were greatly overestimated in comparison with those measured by the improved *** linear correlation （R2=0.9996） between the response of the improved ECD and N2O concentrations （93×10-9-1966×10-9mol/mol） indicated that atmospheric N2O could be accurately quantified via a single standard *** N2O concentrations comparatively measured by the improved method and a high precision GC-ECD method were in good agreement.

关键词： N2O GC-ECD CO2 exchange flux method comparison

Focused Widely Linear Beamforming

在线全文

学校读者我要写书评

暂无评论

Journal of Beijing Institute of Technology 2019年第4期28卷 744-749页

作者： Yougen Xu junfeng liu Zhiwen liu School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China

The problem addressed in this paper concerns the extension of widely linear beamforming to the wideband case,developing a wide-focused linear beamformer for the extraction of a wideband second-order(SO)noncircular signal-of-interest(SOI)contaminated by uncorrelated interferences and *** the proposed beamformer,the beamforming array observation is first focused to adopt a standard linear minimum variance distortionless response(MVDR)*** augmented SOI steering vector then is obtained by estimating the SOI noncircularity parameter with the newly proposed oblique projection with an augmented sparse representation *** covariance matrix of the virtual interference,true interference and noise is further reconstructed using the newly presented complementary spatial spectrum *** wideband widely linear spatial filtering is finally realized via MVDR like *** performance of the proposed beamformer is verified by simulation.

关键词： array signal processing adaptive beamforming direction-of-arrival estimation noncircularity wideband

Levels,sources and health risks of carbonyls and BTEX in the ambient air of Beijing,China

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2012年第1期24卷 124-130页

作者： Yujie Zhang Yujing Mu junfeng liu Abdelwahid Mellouki Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Centre National de Recherche Scientifique-Institut de Combustion AerothermiqueReactivite et Environnement(CNRS-ICARE)45071 Orleans cedex 02France

The atmospheric concentrations of carbonyls and BTEX （benzene,toluene,ethylbenzene,m,p-xylene and o-xylene） were measured simultaneously at a same sampling site in Beijing from September 2008 to August *** average concentrations of the total measured carbonyls during autumn,winter,spring,and summer were 37.7,31.3,39.7,50.5 μg/m 3,respectively,and maximal values for their diurnal variations usually happened at *** contrast to carbonyls,the average concentrations of the total measured BTEX during the four seasons were 27.2,31.9,23.2,19.1 μg/m 3,respectively,andminimal values for their diurnal variations always occurred in the early *** average concentration for carbonyls increased about 24% from September 2008–August 2009 to September 2009–August 2010,for BTEX,increased about 15%.Integrated life time cancer risks for three carcinogens （benzene,formaldehyde and acetaldehyde） in Beijing exceeded the value of 1E-06,and the hazard quotient （HQ） of non-cancer risk of exposure to formaldehyde exceeded unity.

关键词： carbonyls BTEX sources exposure and risk assessment Beijing

中俄与中亚国家地缘经济联系演变及其影响因素

在线全文

学校读者我要写书评

暂无评论

经济地理 2024年第5期44卷 1-11页

作者：胡伟于书洋葛岳静刘峻峰张建珍胡渊浙江师范大学地理与环境科学学院浙江金华321004 浙江师范大学流域地表过程与生态安全重点实验室浙江金华321004 北京师范大学地理科学学部北京100875 苏州科技大学商学院江苏苏州215009 东北财经大学经济学院辽宁大连116025

文章构建了多维度地缘经济联系强度评价指标体系,运用多边形法、向量和法和灰色关联分析法比较分析了中俄与中亚国家地缘经济联系强度演变,剖析了中俄两国与中亚国家地缘经济联系强度的影响因素。结果表明:(1)中国与中亚国家地缘经济联... 详细信息

文章构建了多维度地缘经济联系强度评价指标体系,运用多边形法、向量和法和灰色关联分析法比较分析了中俄与中亚国家地缘经济联系强度演变,剖析了中俄两国与中亚国家地缘经济联系强度的影响因素。结果表明:(1)中国与中亚国家地缘经济联系整体强度呈波动增长态势,俄罗斯与中亚国家地缘经济整体联系强度基本保持稳定,俄罗斯与中亚国家整体地缘经济联系强度高于中国。(2)地缘政治在中俄与中亚国家地缘经济联系中的作用下降,贸易和交通在中俄与中亚国家地缘经济联系中的地位上升。中国与中亚国家的地缘经济联系由贸易、交通、地缘政治共同主导逐步转为贸易和投资共同主导,俄罗斯与中亚国家地缘政治联系由旅游、贸易、地缘政治共同主导转变为贸易、旅游、交通共同主导。(3)中俄与中亚国家地缘经济联系强度均呈北高南低阶梯格局,但俄罗斯与哈萨克斯坦以南4国地缘经济联系强度空间格局波动起伏较大。(4)资源禀赋是中俄与中亚国家地缘经济联系强度演变的共同重要驱动力,中国与中亚国家地缘经济联系比俄罗斯更依赖市场规模,俄罗斯与中亚国家地缘经济联系对经济发展水平和政治稳定性比中国更为敏感。

关键词：地缘经济联系多边形法 “一带一路”倡议中国俄罗斯中亚国家

基于双PLC和工控机的定位绞车变频电控系统设计研究

在线全文

学校读者我要写书评

暂无评论

现代工程科技 2024年第8期3卷 77-80页

作者：刘传德刘俊峰陈雷上海振华重工(集团)股份有限公司上海200125

为提升海洋工程中定位绞车的控制精度和操作效率,研究设计了基于双可编程逻辑控制器(Programmable Logic Controller,PLC)和工控机的定位绞车变频电控系统。首先阐述了移船定位绞车在海洋工程中的重要作用,随后深入分析了以西门子系列... 详细信息

为提升海洋工程中定位绞车的控制精度和操作效率,研究设计了基于双可编程逻辑控制器(Programmable Logic Controller,PLC)和工控机的定位绞车变频电控系统。首先阐述了移船定位绞车在海洋工程中的重要作用,随后深入分析了以西门子系列为基础的双PLC控制系统的电气设计,并探讨了包括Profibus、Profinet及光纤通信在内的通信系统,强调其在提高系统稳定性和安全性中的作用。通过案例研究,展示了该设计方案的应用效果和技术挑战,为海洋工程中类似系统的设计提供了有价值的参考。

关键词：双PLC 工控机定位绞车变频电控系统监控系统

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

吉他霉素纳米凝胶制备与评价

中国畜牧兽医 2024年第4期51卷 1737-1745页

作者：马蓓王天扬丁泽董天祯刘盼张耀锋刘俊峰塔里木大学动物科学与技术学院阿拉尔843300 新疆生产建设兵团塔里木动物疫病诊断与防控工程实验室阿拉尔843300

【目的】制备一种可局部递送吉他霉素用于皮肤创口感染的纳米凝胶。【方法】以京尼平为交联剂在希夫碱作用下,通过凝胶材料之间的静电作用制备壳聚糖/明胶/聚乙烯醇纳米凝胶,并载入药物吉他霉素,对其包封率、载药量、溶胀性能、纳米粒径... 详细信息

【目的】制备一种可局部递送吉他霉素用于皮肤创口感染的纳米凝胶。【方法】以京尼平为交联剂在希夫碱作用下,通过凝胶材料之间的静电作用制备壳聚糖/明胶/聚乙烯醇纳米凝胶,并载入药物吉他霉素,对其包封率、载药量、溶胀性能、纳米粒径、Zeta电位、微观结构扫描等表征结构及生物安全性进行测试,评估纳米凝胶的体外释放效果和伤口愈合活性。【结果】本研究制备的吉他霉素纳米凝胶,在其组方为每25 mL凝胶中含吉他霉素0.25 g、壳聚糖0.4 g、明胶0.3 g、聚乙烯醇0.2 g,京尼平0.2 g,其余量为去离子水时外观性状为淡蓝色纳米凝胶,无沉淀与药物析出,溶胀度高,载药量为13.6%,包封率为83.1%;扫描电镜下可见该纳米凝胶形成孔隙致密且分布均匀的三维网状结构;平均粒径为28.56 nm,Zeta电位为16.33 mV;生物安全性良好;纳米凝胶在体外释放药物可维持48 h,明显长于吉他霉素溶液的释放时间。此外,纳米凝胶还能使小鼠伤口缩小96%,有助于伤口愈合。【结论】本研究成功制备了吉他霉素纳米凝胶,通过体内体外试验评估证明了其潜在的药物控释与促进皮肤伤口愈合的能力。

关键词：吉他霉素纳米凝胶药物控释伤口愈合

在线全文

学校读者我要写书评

暂无评论

动力电池电池箱轻量化设计

农业装备与车辆工程 2024年第3期62卷 45-49页

作者：刘俊峰康元春湖北汽车工业学院汽车工程学院湖北十堰442002 汽车动力传动与电子控制湖北省重点实验湖北十堰442002

为轻量化电池箱并保证其强度、刚度和安全性能,对比了在尺寸优化阶段引入安全性评价指标与否2种方法。首先对电池箱进行了静力分析、模态分析和挤压仿真,然后是形貌优化和尺寸优化。在尺寸优化阶段,以挤压作为安全性评价指标,同时考虑... 详细信息

为轻量化电池箱并保证其强度、刚度和安全性能,对比了在尺寸优化阶段引入安全性评价指标与否2种方法。首先对电池箱进行了静力分析、模态分析和挤压仿真,然后是形貌优化和尺寸优化。在尺寸优化阶段,以挤压作为安全性评价指标,同时考虑静力分析和模态分析,对比了2种多目标优化方案,最终确定了电池箱各板件的厚度。优化结果表明,在尺寸优化阶段引入安全性指标,电池模组变形量减少了43.08%,且电池箱质量减少了20.81%。在轻量化的同时保证了强度刚度和安全性能。

关键词：电池箱轻量化多目标优化

Rural vehicle emission as an important driver for the variations of summertime tropospheric ozone in the Beijing-Tianjin-Hebei region during 2014-2019

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2022年第4期34卷 126-135页

作者： Yifei Song Yuanyuan Zhang junfeng liu Chenglong Zhang Chengtang liu Pengfei liu Yujing Mu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Center for Excellence in Urban Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Tropospheric ozone(O_(3))pollution is increasing in the Beijing-Tianjin-Hebei(BTH)region despite a significant decline in atmospheric fine aerosol particles(PM_(2.5))in recent ***,the intrinsic reason for the elevation of the regional O_(3)is still *** this study,we analyzed the spatio-temporal variations of tropospheric O_(3)and relevant pollutants(PM_(2.5),NO_(2),and CO)in the BTH region based on monitoring data from the China Ministry of Ecology and Environment during the period of *** results showed that summertime O_(3)concentrations were constant in Beijing(BJ,0.06μg/(m^(3)·year))but increased significantly in Tianjin(TJ,9.09μg/(m^(3)·year))and Hebei(HB,6.06μg/(m3·year)).Distinct O_(3)trends between Beijing and other cities in BTH could not be attributed to the significant decrease in PM_(2.5)(from-5.08 to-6.32μg/(m3·year))and CO(from-0.053 to-0.090 mg/(m^(3)·year))because their decreasing rates were approximately the same in all the *** relatively stable O_(3)concentrations during the investigating period in BJ may be attributed to a faster decreasing rate of NO_(2)(BJ:-2.55μg/(m^(3)·year);TJ:-1.16μg/(m^(3)·year);HB:-1.34μg/(m3·year)),indicating that the continued reduction of NOx will be an effective mitigation strategy for reducing regional O_(3)*** positive correlations were found between daily maximum8 hr average(MDA8)O_(3)concentrations and vehicle population and highway freight transportation in ***,we speculate that the increase in rural NO_(x)emissions due to the increase in vehicle emissions in the vast rural areas around HB greatly accelerates regional O_(3)formation,accounting for the significant increasing trends of O_(3)in HB.

关键词： Tropospheric ozone The Beijing-Tianjin-Hebei region Spatio-temporal trends Rural vehicle emission

基于ESP32与微信小程序的智能家居控制系统

在线全文

学校读者我要写书评

暂无评论

科技创新与应用 2024年第25期14卷 41-44页

作者：刘俊峰乔有田扬州市职业大学江苏扬州225200

针对人们对家居环境的智能化需求,实现对家居实时监测,设计基于ESP32与微信小程序的智能家居控制系统。该系统采用DHT11、MQ2、MQ5和MQ7传感器分别对温湿度、CO、液化气和烟雾的浓度进行监测。以ESP32作为主控芯片和Wi-Fi通信模块进行... 详细信息

针对人们对家居环境的智能化需求,实现对家居实时监测,设计基于ESP32与微信小程序的智能家居控制系统。该系统采用DHT11、MQ2、MQ5和MQ7传感器分别对温湿度、CO、液化气和烟雾的浓度进行监测。以ESP32作为主控芯片和Wi-Fi通信模块进行数据传输,传输到OneNet云平台及微信小程序进行监测和控制。经测验,该系统具备成本低廉、功能稳定等优点,满足实际应用需求。

关键词：物联网 OneNet ESP32 微信小程序智能家居