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961.
蓝藻的防控与治理是湖泊水环境、水生态管理的重要内容,实时获取蓝藻的空间分布信息对于降低蓝藻灾害风险具有重要意义.针对地面调查费时费力、卫星遥感监测粒度较粗且时效性不强等问题,本文提出了一种基于视频监控网络的湖泊蓝藻实时监测技术.基于环巢湖视频监控网络的33个功能摄像机,研究如何从视频图像中实时、准确提取蓝藻的分布信息.为克服不同摄像头的观测角度不一致、光照强度和背景条件不一致等诸多挑战,在视频图像蓝藻表征分析的基础上,通过多尺度深度网络进行图像粗粒度分类,区分蓝藻与浑浊、阴影水体;基于随机森林进行蓝藻精细化识别,克服蓝藻的强异质性.最后以渔政站沿岸水域的日均蓝藻覆盖率和月均蓝藻覆盖率为统计单位,开展了巢湖沿岸蓝藻的动态监测.研究成果可为科学制定蓝藻治理方案提供技术支撑. 相似文献
962.
A novel design for a giant Arecibo-type spherical radio telescope with an active main reflector 总被引:8,自引:0,他引:8
Yuhai H. Qiu 《Monthly notices of the Royal Astronomical Society》1998,301(3):827-830
A novel design for a giant spherical radio telescope is proposed. Instead of a fixed spherical reflecting surface such as with the 305-m Arecibo telescope, the illuminated portion of the reflecting surface is made to fit a paraboloid of revolution in real time by active control. A simple feed can thus be used, enabling the realization of broad bandwidth and full polarization. The actual design utilizes a karst depression which gives a spherical surface of 300-m radius, having an opening of 500-m diameter. The illuminated aperture is chosen to be 300 m, and the focal ratio is 0.46–0.48. With this geometry and the simple feeding system, a giant telescope with large sky coverage can be achieved at low cost. When the illuminated aperture is limited to 70–100 m, the area trackable can be extended to about 10° above the horizon. 相似文献
963.
CENOZOIC VOLCANISM AND GEOTHERMAL RESOURCES IN NORTHEAST CHINA 总被引:2,自引:0,他引:2
WANG Xi-kui QIU Shan-wen SONG Chang-chun KULAKOV Aleksey TASHCHI Stepan MYASNIKOV Evgeny 《中国地理科学(英文版)》2001,11(2):150-154
1 INTRODUCTION Northeast China is located in the eastern marginal part of Eurasian plate. There are about 700 Cenozoic volcanoes and about 50 000km2 volcanic rocks in Northeast China. The Cenozoic volcanism is related to the Pacific plate subducting, back-arc spreading and corresponding marginal continental rifting. About 700 Cenozoic volcanoes in Northeast China are concentrated at some places, so Shuangliao, Keluo, Wudalianchi, Yitong, Shulan, Shangzhi, Longgang, Jingbo Lake, … 相似文献
964.
钻孔体应变高采样率观测实验 总被引:5,自引:0,他引:5
分析TJ-2型钻孔应变仪记录与测震仪记录的结果表明:该应变仪对于100 Hz的采样率有良好的频率响应,能够记录完整的地震波;从近震到极远震,其频响范围与测震仪基本一致,且频响的变化一致性很好,在一定的约束条件下,应变地震波与地震波在时域与频率域能够高度吻合;但该应变仪记录的S波较弱。 相似文献
965.
THE MAIN FEATURES OF MORPHOSTRUCTURE OFTHE TRANSREGIONAL AMUR-SONGHUA-HUANGHEFAULT ZONE IN EAST ASIA
DuringthelastseveralyearstheRussian-Chinese~tivemorphOStructUralinvestigationswerecarriedoutalongthetransregionalfaultzonewhichstretcheSmorethan3000kin,fromlowerstreamoftheHuanghecaver,ac~theffehaho,Liaohedep~ion,thenalongthehahuaandthelowerAInurvalleystotheNorthffekhalinandprobablytothecentralPartofOkhotskAsbasin.It'soneofthelargestfaultzonesintheeasternrnalginofAsia.OntheterritoryofnortheasternChinathemostpinOfthiszoneiskno~asTall-L.faultzonewhichhasbeenstudiedbyChinesegeologistsform… 相似文献
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Gao Kai Liu Yanjie Ding Lin Huang Shuai Qiu Kaichi Wang Zhongpan Yang Yang Liu Xing Li Jiaxin 《地震工程与工程振动(英文版)》2021,20(4):1007-1019
The permafrost of Mohe County and its suburbs in the Daxing′an Mountains has been influenced by the urbanization. Remote sensing, GIS technology and numerical simulation was used to study the temperature variations of permafrost with the changes in surface vegetation that cover Mohe County and suburban areas, and the law of permafrost degradation on the study area was analyzed. The research results show that the urban area of the study area increased 114.42%from 2000 to 2016, and the urbanization process is continuing to accelerate. The Normalized Difference Vegetation Index map of 2017 in Mohe County and its suburbs was studied and the maximum proportion of vegetation coverage was different in the four seasons. The numerical calculation model results show that the permafrost temperature change in the study area cyclically fluctuates in a cosine form. The annual variation curve of permafrost temperature gradually decreased and its accompanying phase lag increased with depth. The annual temperature change value with the different depths of the town was greater than the natural ground. The maximum permafrost thawing depths of the town and natural ground were 4.2 m and 2.82 m in 50 a, and the degradation rates of the two permafrost are, respectively, 0.88 cm/a and 0.46 cm/a. These results show that urbanization has accelerated the degradation of permafrost. 相似文献
970.
Zhang Jianlei Cheng Qiangong Li Yan Qiu Yuheng Wang Yufeng Wu Jiujiang 《地震工程与工程振动(英文版)》2021,20(4):905-923
The performance of rectangular closed diaphragm walls(RCDW) subjected to earthquake ground motions is extremely complicated in gently sloping liquefiable deposits and requires further investigation. A nonlinear finite element(FE) model was developed to investigate the seismic performance of an RCDW in the OpenSees platform. Initially, the feasibility of the FE model to simulate the seismic behavior of the RCDW was validated by comparing the numerical results with the experimental data. The numerical results agree well with the centrifuge test data. Then, the calibrated model was used to study the seismic performance of the RCDW subjected to different ground motions in gently sloping liquefiable deposits.The numerical results indicate that the soil-RCDW system under near-fault ground motions is more likely to be damaged than that under far-fault ground motions. The difference between the maximum and minimum(D_(max-min)) the RCDW displacement and the maximum excess pore pressure in the soil core increased as the Arias intensity increased. The seismic response of the soil-RCDW system was strongly affected by the frequency content, durations, energy distribution and initial directions of the ground motions. Moreover, the modified specific energy density(MSED) has a good linear relationship with the D_(max-min) of the RCDW displacement. 相似文献