近些年城市大气污染问题尤为突出,其中PM2.5、PM10等污染物是引起雾霾天气的重要因素.本文基于2007—2016年10年中全国主要城市SO2、NO2、PM10等污染物因子的年平均浓度变化,利用Ocean Data View软件分析主要城市大气污染主控因子(二氧...近些年城市大气污染问题尤为突出,其中PM2.5、PM10等污染物是引起雾霾天气的重要因素.本文基于2007—2016年10年中全国主要城市SO2、NO2、PM10等污染物因子的年平均浓度变化,利用Ocean Data View软件分析主要城市大气污染主控因子(二氧化硫、氮氧化物以及颗粒物)的排放特征及其成因.结果表明:各污染物的区域性分布明显,污染物浓度变化的总体趋势北方高于南方,SO2、NO2、PM10年平均浓度北方分别高于南方108.15%、7.60%、48.36%;从大气污染组分来看,颗粒物的增长速度最快,石家庄2007—2016年PM10增速为28.10%;而SO2的污染物浓度在下降,乌鲁木齐的降速为84.10%.展开更多
To efficiently solve the materialized view selection problem, an optimal genetic algorithm of how to select a set of views to be materialized is proposed so as to achieve both good query performance and low view maint...To efficiently solve the materialized view selection problem, an optimal genetic algorithm of how to select a set of views to be materialized is proposed so as to achieve both good query performance and low view maintenance cost under a storage space constraint. First, a pre-processing algorithm based on the maximum benefit per unit space is used to generate initial solutions. Then, the initial solutions are improved by the genetic algorithm having the mixture of optimal strategies. Furthermore, the generated infeasible solutions during the evolution process are repaired by loss function. The experimental results show that the proposed algorithm outperforms the heuristic algorithm and canonical genetic algorithm in finding optimal solutions.展开更多
Multi-view laser radar （ladar） data registration in obscure environments is an important research field of obscured target detection from air to ground. There are few overlap regions of the observational data in dif...Multi-view laser radar （ladar） data registration in obscure environments is an important research field of obscured target detection from air to ground. There are few overlap regions of the observational data in different views because of the occluder, so the multi-view data registration is rather difficult. Through indepth analyses of the typical methods and problems, it is obtained that the sequence registration is more appropriate, but needs to improve the registration accuracy. On this basis, a multi-view data registration algorithm based on aggregating the adjacent frames, which are already registered, is proposed. It increases the overlap region between the pending registration frames by aggregation and further improves the registration accuracy. The experiment results show that the proposed algorithm can effectively register the multi-view ladar data in the obscure environment, and it also has a greater robustness and a higher registration accuracy compared with the sequence registration under the condition of equivalent operating efficiency.展开更多
气候和生物地球化学循环作为海洋科学研究的重要领域,充分利用和深入挖掘海洋地球化学数据的需求日益增长。由于对海洋大规模直接观测难度较高,且海洋内部结构复杂、相互作用过程多样,通过研究数据解译海洋地球化学过程机制和海洋在生...气候和生物地球化学循环作为海洋科学研究的重要领域,充分利用和深入挖掘海洋地球化学数据的需求日益增长。由于对海洋大规模直接观测难度较高,且海洋内部结构复杂、相互作用过程多样,通过研究数据解译海洋地球化学过程机制和海洋在生物地球化学循环中的作用往往需要对多种海洋物理和化学参数进行协同分析。海洋数据可视化软件作为高质量呈现数据视图的媒介,具备分析、处理、可视化数据的强大功能,可作为直观研究海洋学数据的有力工具。目前,国内关于海洋数据可视化软件的介绍多侧重原理,缺乏关于具体操作方面的指导。本文详细介绍了Ocean Data View(ODV)和Java OceanAtlas(JOA)的基本操作及数据可视化流程,对断面图、平面图、瀑布图等多类图式的绘制和数据分析方法进行说明,并对比这两种软件的差别;通过实例介绍ODV的开发功能在处理和可视化数据方面的优势及其在海洋地球化学等研究领域的具体应用,以期为海洋地球化学领域的科研人员提供参考和帮助。展开更多
文摘近些年城市大气污染问题尤为突出,其中PM2.5、PM10等污染物是引起雾霾天气的重要因素.本文基于2007—2016年10年中全国主要城市SO2、NO2、PM10等污染物因子的年平均浓度变化,利用Ocean Data View软件分析主要城市大气污染主控因子(二氧化硫、氮氧化物以及颗粒物)的排放特征及其成因.结果表明:各污染物的区域性分布明显,污染物浓度变化的总体趋势北方高于南方,SO2、NO2、PM10年平均浓度北方分别高于南方108.15%、7.60%、48.36%;从大气污染组分来看,颗粒物的增长速度最快,石家庄2007—2016年PM10增速为28.10%;而SO2的污染物浓度在下降,乌鲁木齐的降速为84.10%.
文摘To efficiently solve the materialized view selection problem, an optimal genetic algorithm of how to select a set of views to be materialized is proposed so as to achieve both good query performance and low view maintenance cost under a storage space constraint. First, a pre-processing algorithm based on the maximum benefit per unit space is used to generate initial solutions. Then, the initial solutions are improved by the genetic algorithm having the mixture of optimal strategies. Furthermore, the generated infeasible solutions during the evolution process are repaired by loss function. The experimental results show that the proposed algorithm outperforms the heuristic algorithm and canonical genetic algorithm in finding optimal solutions.
文摘Multi-view laser radar （ladar） data registration in obscure environments is an important research field of obscured target detection from air to ground. There are few overlap regions of the observational data in different views because of the occluder, so the multi-view data registration is rather difficult. Through indepth analyses of the typical methods and problems, it is obtained that the sequence registration is more appropriate, but needs to improve the registration accuracy. On this basis, a multi-view data registration algorithm based on aggregating the adjacent frames, which are already registered, is proposed. It increases the overlap region between the pending registration frames by aggregation and further improves the registration accuracy. The experiment results show that the proposed algorithm can effectively register the multi-view ladar data in the obscure environment, and it also has a greater robustness and a higher registration accuracy compared with the sequence registration under the condition of equivalent operating efficiency.
文摘气候和生物地球化学循环作为海洋科学研究的重要领域,充分利用和深入挖掘海洋地球化学数据的需求日益增长。由于对海洋大规模直接观测难度较高,且海洋内部结构复杂、相互作用过程多样,通过研究数据解译海洋地球化学过程机制和海洋在生物地球化学循环中的作用往往需要对多种海洋物理和化学参数进行协同分析。海洋数据可视化软件作为高质量呈现数据视图的媒介,具备分析、处理、可视化数据的强大功能,可作为直观研究海洋学数据的有力工具。目前,国内关于海洋数据可视化软件的介绍多侧重原理,缺乏关于具体操作方面的指导。本文详细介绍了Ocean Data View(ODV)和Java OceanAtlas(JOA)的基本操作及数据可视化流程,对断面图、平面图、瀑布图等多类图式的绘制和数据分析方法进行说明,并对比这两种软件的差别;通过实例介绍ODV的开发功能在处理和可视化数据方面的优势及其在海洋地球化学等研究领域的具体应用,以期为海洋地球化学领域的科研人员提供参考和帮助。
