创业投资对国家创新能力提升与经济可持续发展有重要意义,为有效解决创业资源配置中的市场失灵及政府直接干预的低效问题,创业投资政府引导基金政策应运而生,并逐渐成为创新创业政策领域的重要研究对象。为把握国外学术界对该问题的研...创业投资对国家创新能力提升与经济可持续发展有重要意义,为有效解决创业资源配置中的市场失灵及政府直接干预的低效问题,创业投资政府引导基金政策应运而生,并逐渐成为创新创业政策领域的重要研究对象。为把握国外学术界对该问题的研究趋势,论文利用斯高帕斯(Scopus)和科学引文索引(Web of Science)数据库,追溯1996—2017年间发表的相关文献,系统阐释了政府干预创业投资与设立引导基金的动机,总结并分析了政府引导基金的概念及其运作模式,梳理了关于政府引导基金分别对创业投资市场发展、创业投资机构投资行为、创业企业成长及创新产出等发挥影响的实证结论,并给出相关研究对改进政策设计的有益启示。结合中国的制度背景,提出本土研究只有通过多主体、全链条的系统性分析,才能在深化理论的同时推动实践发展。展开更多
A method to tighten the cloud screening thresholds based on local conditions is used to provide more stringent schemes for Orbiting Carbon Observatory-2(OCO-2)cloud screening algorithms.Cloud screening strategies are ...A method to tighten the cloud screening thresholds based on local conditions is used to provide more stringent schemes for Orbiting Carbon Observatory-2(OCO-2)cloud screening algorithms.Cloud screening strategies are essential to remove scenes with significant cloud and/or aerosol contamination from OCO-2 observations,which helps to save on the data processing cost and ensure high quality retrievals of the column-averaged CO2 dry air mole fraction(XCO2).Based on the radiance measurements in the 0.76μm O2A band,1.61μm(weak),and 2.06μm(strong)CO2 bands,the current combination of the A-Band Preprocessor(ABP)algorithm and Iterative Maximum A Posteriori(IMAP)Differential Optical Absorption Spectroscopy(DOAS)Preprocessor(IDP)algorithm passes around 20%-25%of all soundings,which means that some contaminated scenes also pass the screening process.In this work,three independent pairs of threshold parameters used in the ABP and IDP algorithms are sufficiently tuned until the overall pass rate is close to the monthly clear-sky fraction from the MODIS cloud mask.The tightened thresholds are applied to observations over land surfaces in Europe and Japan in 2016.The results show improvement of agreement and positive predictive value compared to the collocated MODIS cloud mask,especially in summer and fall.In addition,analysis indicates that XCO2 retrievals with more stringent thresholds are in closer agreement with measurements from collocated Total Carbon Column Observing Network(TCCON)sites.展开更多
文摘创业投资对国家创新能力提升与经济可持续发展有重要意义,为有效解决创业资源配置中的市场失灵及政府直接干预的低效问题,创业投资政府引导基金政策应运而生,并逐渐成为创新创业政策领域的重要研究对象。为把握国外学术界对该问题的研究趋势,论文利用斯高帕斯(Scopus)和科学引文索引(Web of Science)数据库,追溯1996—2017年间发表的相关文献,系统阐释了政府干预创业投资与设立引导基金的动机,总结并分析了政府引导基金的概念及其运作模式,梳理了关于政府引导基金分别对创业投资市场发展、创业投资机构投资行为、创业企业成长及创新产出等发挥影响的实证结论,并给出相关研究对改进政策设计的有益启示。结合中国的制度背景,提出本土研究只有通过多主体、全链条的系统性分析,才能在深化理论的同时推动实践发展。
基金the National Key Research Program of China(Grant No.2016YFC0200900)the National Natural Science Foundation of China(NSFC)(Grant No.41775023)+1 种基金the Excellent Young Scientists Program of the Zhejiang Provincial Natural Science Foundation of China(Grant No.LR19D050001)the Fundamental Research Funds for the Central Universities,and the State Key Laboratory of Modern Optical Instrumentation Innovation Program.
文摘A method to tighten the cloud screening thresholds based on local conditions is used to provide more stringent schemes for Orbiting Carbon Observatory-2(OCO-2)cloud screening algorithms.Cloud screening strategies are essential to remove scenes with significant cloud and/or aerosol contamination from OCO-2 observations,which helps to save on the data processing cost and ensure high quality retrievals of the column-averaged CO2 dry air mole fraction(XCO2).Based on the radiance measurements in the 0.76μm O2A band,1.61μm(weak),and 2.06μm(strong)CO2 bands,the current combination of the A-Band Preprocessor(ABP)algorithm and Iterative Maximum A Posteriori(IMAP)Differential Optical Absorption Spectroscopy(DOAS)Preprocessor(IDP)algorithm passes around 20%-25%of all soundings,which means that some contaminated scenes also pass the screening process.In this work,three independent pairs of threshold parameters used in the ABP and IDP algorithms are sufficiently tuned until the overall pass rate is close to the monthly clear-sky fraction from the MODIS cloud mask.The tightened thresholds are applied to observations over land surfaces in Europe and Japan in 2016.The results show improvement of agreement and positive predictive value compared to the collocated MODIS cloud mask,especially in summer and fall.In addition,analysis indicates that XCO2 retrievals with more stringent thresholds are in closer agreement with measurements from collocated Total Carbon Column Observing Network(TCCON)sites.
