基于多特征融合与典型降维方法的高光谱影像分类     

窦世卿  陈治宇  徐勇  郑贺刚  苗林林  宋莹莹 《测绘通报》2022,(4):32-36+50

高光谱影像的冗余信息给影像的分类效果带来一定的负面影响。本文利用CB法(CfsSubsetEval评估器结合Best-First搜索策略)与PCA变换两种降维方法,分别结合随机森林分类器对4种多特征融合方案(共8种组合)进行高光谱影像分类对比,基于分类的总体精度、Kappa系数探究提高高光谱影像分类的最佳组合方法。结果表明:①多特征融合可提升高光谱影像的分类效果,两种降维方法的分类精度均随地理特征、纹理特征、指数特征的加入而逐渐提高。②两种降维方法中,经CB法降维后的分类精度均比通过PCA变换降维的分类精度高。在构造的8种组合中,基于所有特征信息(光谱特征、地理特征、纹理特征、指数特征)的CB法分类精度最高,其总体精度为98.01%;Kappa系数为0.969 9。  相似文献   

Shallow water tidal currents in close proximity to the seafloor and boundary-induced turbulence   总被引：1，自引：0，他引：1  

Iossif Lozovatsky  Zhiyu Liu  Harindra Fernando  Jordi Armengol  Elena Roget 《Ocean Dynamics》2012,62(2):177-191

Velocity measurements with vertical resolution 0.02 m were conducted in the lowest 0.5 m of the water column using acoustic Doppler current profiler (ADCP) at a test site in the western part of the East China Sea. The friction velocity u _* and the turbulent kinetic energy dissipation rate ε _wl(ζ) profiles were calculated using log-layer fits; ζ is the height above the bottom. During a semidiurnal tidal cycle, u _* was found to vary in the range (1–7) × 10⁻³ m/s. The law-of-the-wall dissipation profiles ε _wl(ζ) were consistent with the dissipation profiles ε _mc(ζ) evaluated using independent microstructure measurements of small-scale shear, except in the presence of westward currents. It was hypothesized that an isolated bathymetric rise (25 m height at a 50-m seafloor) located to the east of the measurement site is responsible for the latter. Calculation of the depth integrated internal tide generating body force in the region showed that the flanks of the rise are hotspots of internal wave energy that may locally produce a significant turbulent zone while emitting tidal and shorter nonlinear internal waves. This distant topographic source of turbulence may enhance the microstructure-based dissipation levels ε _mc(ζ) in the bottom boundary layer (BBL) beyond the dissipation ε _wl(ζ) associated with purely locally generated turbulence by skin currents. Semi-empirical estimates for dissipation at a distance from the bathymetric rise agree well with the BBL values of ε _mc measured 15 km upslope.  相似文献   

朱溪矿集区横路矿区成矿条件与找矿潜力分析   总被引：1，自引：0，他引：1       下载免费PDF全文

魏锦  许杰辉  王先广  严加永  张雪辉  刘建光  孟德磊  何细荣  饶建锋  蒙智宇  欧阳永棚 《中国地质》2019,46(4):906-918

横路矿区位于朱溪矿集区内,其成矿条件与世界最大钨矿床--朱溪矿床类似,目前已发现了多处找矿线索,但前期工作主要聚焦于500 m以浅,亟待探索该区深部找矿前景。本文从矿区地质、地球物理、地球化学、遥感特征及钻探验证等方面综合分析,并与朱溪矿区进行对比,发现二者在成矿地层层位、控岩控矿构造以及岩浆岩所处成岩-成矿事件等重要成矿条件上极为相似。此外,横路矿区的浅表矿化蚀变分布情况与岩脉密切相关,物化探异常及岩脉分布特征显示深部存在隐伏岩体。综合分析认为横路矿区深部找矿潜力巨大,具有找寻破碎带(热液脉)型、矽卡岩型及斑岩型铜钼金多金属矿床的良好前景。  相似文献   

Variations in the environmental characteristics of groundwater slightly contaminated with petroleum: effects of enhanced bioremediation in northeast China     

Yuling Zhang  Hong Qian  Jiali Wang  Chaoqun Si  Zhiyu Chen  Jiangyan Dang  Zhenyi Zhang 《Environmental Earth Sciences》2017,76(2):90

The objective of this paper was to investigate a petroleum-contaminated groundwater site in northeast China. Based on the monitoring and analysis of environmental characteristics of groundwater slightly contaminated with petroleum, microbes were added into the petroleum-contaminated groundwater via single-well and multiple-well models to enhance bioremediation. The effect of enhanced bioremediation was monitored and analyzed, and variations in the environmental characteristics of groundwater containing total petroleum hydrocarbons (TPH) were identified to provide a scientific basis for controlling and remediating petroleum-contaminated groundwater. Findings confirmed that this site was slightly contaminated and TPH levels exhibited a slight decreasing trend. After enhanced remediation, the microbial degradation effect was large, and the TPH concentration significantly reduced. In particular, near the wells treated by bioremediation, the amounts of electron acceptors, such as NO₃ ^?, Fe³⁺, and SO₄ ^2?, markedly decreased. The product of the microbial degradation process, HCO₃ ^?, gradually increased in the treated wells. Activities of the enzyme catechol 1, 2-dioxygenase decreased, while those of catalase increased. Reductions in pH, from 7.4 to 6.1, were recorded, and the groundwater environment became further deoxidized.  相似文献   

气候变化对淮河蒙洼蓄滞洪区启用风险影响评估   总被引：1，自引：0，他引：1  

吴志勇  刘志雨  肖恒  尹志杰  张亚洲 《气候变化研究进展》2015,11(1):1-7

基于RCP情景下47个IPCC CMIP5气候模式模拟数据和大尺度水文模型VIC,预估了未来（2021-2050年）气候变化对淮河蒙洼蓄滞洪区启用的可能影响。结果表明：与基准期（1971-2000年）相比,多模式预估淮河上游未来多年平均气温一致呈增加趋势,平均增幅范围0.2～1.7℃。不同模式对降水预估差异较大,但有超过70%的模式预估降水呈增加趋势,平均增幅为3.4%～4.1%。未来气候情景下,王家坝断面洪水总体呈增加趋势,20年一遇的洪水强度平均增幅19%,洪水频率将增大,蒙洼蓄滞洪区启用可能更加频繁,启用的风险加大。  相似文献   

Improving event-based rainfall-runoff simulation using an ensemble artificial neural network based hybrid data-driven model   总被引：2，自引：1，他引：1  

Guangyuan Kan  Cheng Yao  Qiaoling Li  Zhijia Li  Zhongbo Yu  Zhiyu Liu  Liuqian Ding  Xiaoyan He  Ke Liang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(5):1345-1370

  相似文献   

辽河盆地新生代构造演化模式   总被引：7，自引：1，他引：6  

陈正乐  马寅生  王小凤  吴铁生  武红岭  殷秀兰  陈宣华  霍光辉  王庆丰  郑治宇  兰秀峰 《地质力学学报》1999,5(2):83-89

辽河盆地新生代火山岩的分布规律和岩石学特征表明：辽河盆地新生代的构造环境的为大陆裂谷。地壳深部资料显示了辽河地区存在上地幔隆起,它控制了浅部构造的发育。而辽河盆地新生代断裂构造组合,反演出辽河盆地新生代４期的构造应力作用方式。为此,笔者将造山和成盆作用纳入统一的动力学机制,提出了辽河盆地新生代构造演化的动力学模式。  相似文献   

Thank you to 2022 Ocean Dynamics reviewers     

Ezer  Tal  Carniel  Sandro  Amin  Chabchoub  de Camargo  Ricardo  Estrada-Allis  Sheila N.  Gao  Guoping  Greatbatch  Richard J.  Lermusiaux  Pierre F. J.  Liu  Zhiyu  Miyazawa  Yasumasa  Forster  Alejandro Orfila  Panickal  Swapna  Phillips  Helen  Pinones  Andrea  Stanev  Emil  Volker  Christoph  Xu  Fanghua  Young  Emma 《Ocean Dynamics》2023,73(1):35-38

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三峡水库水环境与水生态研究的进展与展望   总被引：4，自引：0，他引：4  

蔡庆华  孙志禹 《湖泊科学》2012,24(2):169-177

伴随着举世瞩目的三峡工程全面竣工,三峡水库于2010年正式进入年水位落差达30 m的正常运行阶段.水库湖沼学可为环境友好型大坝建设和水库可持续管理提供科学依据.本文在三峡成库8 a以来生态系统长期监测与研究的基础上,对三峡水库水环境现状进行了归纳和总结,分析了水环境动态的时空异质性、水库纵向分区与群落组成、垂向分布及藻类水华的成因和动态,并对三峡水库藻类水华预警与生态-水文调控机制展开了论述.最后,本文尝试给出以下两方面的展望:1)大型水库湖沼学观测研究应有长期的策略;2)近期研究应重点关注水华暴发水动力学机制的量化和水华预警模型及生态水力调度平台的耦合.  相似文献   

美国TXAR台阵建设过程     

王志宇  郝春月 《地震地磁观测与研究》2020,41(6):144-149

TXAR台阵位于美国德克萨斯州,是IMS下属的主要地震台阵之一。该台阵将台站数目压缩到9个,采用无线遥测通讯方式,减少了建设和运行维护成本。其地震计室采用钻孔加套管的形式,具有安装简易、密封性好的优点。台阵采用无人值守设计,使用太阳能板、UPS电池和燃油发电机等多种供电方式,具有可靠稳定的性能。  相似文献