Submicron aerosols （PMt） in Beijing were studied using an Aerodyne aerosol mass spectrometer （AMS） from January to Oc tober 2008. This paper presents seasonal variations of different chemical components （sulfate,...Submicron aerosols （PMt） in Beijing were studied using an Aerodyne aerosol mass spectrometer （AMS） from January to Oc tober 2008. This paper presents seasonal variations of different chemical components （sulfate, nitrate, ammonium, chloride and organics） and size distributions of PM1. Results show that mass concentration of PMI was highest in summer, and lowest in autumn. Organics represented the dominant species in all seasons, accounting for 36%58% of PML, and their concentrations were highest in winter. Concentrations of inorganic components, sulfate, nitrate, and ammonium were highest in summer. Based on principal component analysis, organics were deconvolved and quantified as hydrocarbonlike and oxygenated organ ic aerosol （HOA and OOA, respectively）. HOA was highest in winter, accounting for about 70% of organics. However, OOA was highest in summer, and had lower values in autumn and winter. A similar diurnal pattern of various components was ob served, which is higher at nighttime and lower during daytime. HOA increased more dramatically than other species between 17：00 and 21：00 and peaked at noon, which could be related to cooking emissions. OOA, sulfate, nitrate, ammonium and chlo ride varied with the same trend. Their concentrations increased with solar radiation from 9：00 to 13：00, and declined with weakening solar radiation. Size distributions of all species showed apparent peaks in the range 500600 nm. Size distributions of organics were much broader than other species, particularly in autumn and winter. Distributions of sulfate, nitrate and am monium had similar patterns, broadening in winter. Contributions of different species were sizedependent; the finer the parti cle, the greater the contribution of organics. Organics represented more than 60% of particles smaller than 200 nm, contrib uting 50% to PM1 in winter. In spring and summer, HOA was the dominant organic fraction for particles smaller than 200 nm, while OOA contributed more to particles larger than 300 nm. In winter, HOA contributed more than OOA to all PM1 particles.展开更多
Complex networks are everywhere. A typical example is software network. How to measure and control coupling interactions of software components is a largely explored research problem in software network. In terms of g...Complex networks are everywhere. A typical example is software network. How to measure and control coupling interactions of software components is a largely explored research problem in software network. In terms of graph theory and linear algebra, this paper investigates a pair of coupling metrics to evaluate coupling interactions between the classes of object-oriented systems. These metrics differ from the majority of existing metrics in three aspects： Taking into account the strength that one class depends on other ones, reflecting indirect coupling, and distinguishing various coupling interaction. An empirical comparison of the novel measures with one of the most widely used coupling metrics is described. Specifically, an experiment about the relationships of this pair metrics is conducted. The result shows that software complexity derived from coupling interaction could not be accurately reflected by one dimension of coupling metric for negative correlation.展开更多
基金supported by National Natural Science Foundation of China (Grant No.41175113)National Basic Research Program of China(Grant No.2011CB403401)+1 种基金China International Science and Technology Cooperation Project(Grant No.2009DFA22800)Chinese Academy of Meteorological Sciences Group Project(Grant No.2010Z002)
文摘Submicron aerosols （PMt） in Beijing were studied using an Aerodyne aerosol mass spectrometer （AMS） from January to Oc tober 2008. This paper presents seasonal variations of different chemical components （sulfate, nitrate, ammonium, chloride and organics） and size distributions of PM1. Results show that mass concentration of PMI was highest in summer, and lowest in autumn. Organics represented the dominant species in all seasons, accounting for 36%58% of PML, and their concentrations were highest in winter. Concentrations of inorganic components, sulfate, nitrate, and ammonium were highest in summer. Based on principal component analysis, organics were deconvolved and quantified as hydrocarbonlike and oxygenated organ ic aerosol （HOA and OOA, respectively）. HOA was highest in winter, accounting for about 70% of organics. However, OOA was highest in summer, and had lower values in autumn and winter. A similar diurnal pattern of various components was ob served, which is higher at nighttime and lower during daytime. HOA increased more dramatically than other species between 17：00 and 21：00 and peaked at noon, which could be related to cooking emissions. OOA, sulfate, nitrate, ammonium and chlo ride varied with the same trend. Their concentrations increased with solar radiation from 9：00 to 13：00, and declined with weakening solar radiation. Size distributions of all species showed apparent peaks in the range 500600 nm. Size distributions of organics were much broader than other species, particularly in autumn and winter. Distributions of sulfate, nitrate and am monium had similar patterns, broadening in winter. Contributions of different species were sizedependent; the finer the parti cle, the greater the contribution of organics. Organics represented more than 60% of particles smaller than 200 nm, contrib uting 50% to PM1 in winter. In spring and summer, HOA was the dominant organic fraction for particles smaller than 200 nm, while OOA contributed more to particles larger than 300 nm. In winter, HOA contributed more than OOA to all PM1 particles.
基金This research is supported by the National Key Basic Research and Development 973 Program of China under Grant No. 2007CB310805, Foundation for the Author of National Excellent Doctoral Dissertation of China under Grant No. 2007B4, the National Natural Science Foundation of China under Grant Nos. 60873083, 60803025, and the National High Technology Research and Development Program of China under Grant No. 2006AA04Z156.
文摘Complex networks are everywhere. A typical example is software network. How to measure and control coupling interactions of software components is a largely explored research problem in software network. In terms of graph theory and linear algebra, this paper investigates a pair of coupling metrics to evaluate coupling interactions between the classes of object-oriented systems. These metrics differ from the majority of existing metrics in three aspects： Taking into account the strength that one class depends on other ones, reflecting indirect coupling, and distinguishing various coupling interaction. An empirical comparison of the novel measures with one of the most widely used coupling metrics is described. Specifically, an experiment about the relationships of this pair metrics is conducted. The result shows that software complexity derived from coupling interaction could not be accurately reflected by one dimension of coupling metric for negative correlation.
