结合变差纹理特征的极化SAR建筑物震害信息提取          下载免费PDF全文

肖修来  翟玮  郭晓  张皓然 《地震工程学报》2020,42(2):568-578

快速评估建筑物地震灾害信息对地震应急救援工作有着指导意义,而极化SAR具有全天候、全天时的特点,因此利用极化SAR图像提取震害信息已逐渐成为研究热点。虽然极化SAR具有丰富的极化信息,但其纹理信息不可忽略,尤其是完好的人工建筑物在图像上呈现规则的纹理特征,而倒塌建筑区域纹理分布杂乱,因此结合纹理信息也可以很好地提取建筑物信息。以2010年玉树地区的全极化SAR数据为研究对象,首先,利用Yamaguchi分解的体散射分量PV提取了SAR图像中的建筑物区域以及道路、水系等非建筑物信息,在此基础上,对相干散射矩阵T11分量中倒塌建筑物、完好建筑区域进行变差计算,根据变差曲线确定变程a后,再对建筑物区域采取窗口m*m(m=3*a)进行变差计算得到变差纹理信息,最后利用FCM算法对变差纹理信息分别提取完好建筑物和倒塌建筑物区域,为了对比分析,文章利用Yamaguchi分解的二次散射分量PD提取完好建筑物区域,与震后光学遥感图像对应样本点进行人工验证,得到完好建筑物的提取精度为80.18%,倒塌建筑物的提取精度为84.54%,道路水系的提取精度为77.58%。  相似文献   

基于企业微信的宁波市地震应急工作助手的设计与实现     

张蓓蕾  彭骁  董君磊  李杲  周浩波 《地震地磁观测与研究》2020,41(4):251-263

通过分析市县地震部门的地震应急组织机构、主要职能、关键流程,设计了地震应急工作助手的需求方案。并应用ASP.NET MVC、HTML5等开发技术,基于企业微信,开发了包括震情服务、灾情服务、应急服务、工作报告、资料查询、通知公告、通信录等7大功能的地震应急工作助手软件。该软件具有相对机动灵活、成本低、易于推广使用的优势。多次地震应急演练使用表明,软件能在较大程度上提高地震应急工作的规范化程度和处置效率。  相似文献   

超声波处理对微囊藻群体光合活性和沉降过程的影响     

谭啸  段志鹏  李聂贵  孙玉童  戴凯文  朱峰 《湖泊科学》2017,29(6):1324-1330

关注微囊藻群体在超声处理下光合活性变化及超声解除后的浮力恢复情况,可以为超声波控藻技术提供理论依据和数据支撑,具有重要的实践意义.本研究采用处理后水柱中叶绿素a浓度的垂向分布比例和叶绿素荧光变化情况分析微囊藻群体在超声波处理下的光合活性变化和沉降过程.结果表明,适量的超声处理(35 kHz、0.0353 W/cm~3)能在避免破裂藻细胞的同时,显著抑制其光合活性;60 s的处理造成了45.5%的光合活性被抑制.然而,在适宜生长条件下,所有实验组藻细胞中受抑制的光合活性均在24 h内恢复至对照组的80%左右.此外,在上述超声条件下,5 s的超声处理能使水柱中叶绿素a浓度在短时间内(0.5 h)的去除率达79.5%.然而,当处理时间小于30 s时,大于90%的沉降藻细胞可在超声解除后的72 h内恢复浮力上浮;而当处理时间延长至60 s以后,藻细胞基本丧失了上浮能力.通过分析发现,超声处理后微囊藻群体的粒径分布对藻细胞沉降及上浮过程起决定性作用,并且还发现微囊藻群体在超声处理时首先表现为藻细胞失去浮力下沉和光合系统受损,进而发生大群体振散.  相似文献   

1958—2017年太湖蒸发量年际变化趋势及主控因子     

荆思佳  肖薇  王晶苑  郑有飞  王伟  刘强  张圳  胡诚 《湖泊科学》2022,34(5):1697-1711

湖泊蒸发对气候变化非常敏感, 是水文循环响应气候变化的指示因子, 因此研究湖泊蒸发的控制因素, 对于理解区域水文循环有重要意义. 本文利用太湖中尺度涡度通量网避风港站观测数据校正JRA-55再分析资料, 驱动CLM4.0-LISSS模型, 并利用2012—2017年涡度相关通量数据和湖表面温度数据检验模型模拟蒸发结果, 验证了该模型在太湖的适用性; 估算了1958—2017年间太湖的湖面蒸发量, 并利用Manner-Kendall趋势检验分析了湖面蒸发的变化趋势, 寻找太湖实际蒸发的年际变化的主控因子. 结果如下: 校正后的JRA-55再分析资料模拟的太湖蒸发与观测值之间存在季节偏差, 但是季节偏差在年尺度上相互抵消, 再分析资料可用于年际尺度太湖蒸发变化的模拟; 1958—2017年间太湖蒸发量以1977年为界, 先下降(-3.6 mm/a), 后增加(2.3 mm/a); 多元逐步回归结果表明, 向下的短波辐射是太湖1958—2017年间太湖蒸发变化的主控因子, 向下的长波辐射、气温、比湿也对湖泊蒸发年际变化有一定影响, 但是风速对蒸发量的年际变化影响不大.  相似文献   

丹江口水库浮游植物群落时空变化及其与环境因子的关系     

肖玉娜  程靖华  莫晓聪  李永蓉  刘晓娟  毕胜 《湖泊科学》2023,35(3):821-832

研究丹江口水库在完成高水位蓄水期间浮游植物群落的时空动态特征可为丹江口水库的水质保护与生态系统结构优化及健康管理提供一定科学依据。本研究基于2018—2020年的水库浮游植物监测数据,结合同期水库水体的理化参数,分析了丹江口水库浮游植物在不同年度、季度及空间的变化特征,以及影响浮游植物群落结构变化的主要环境因子。结果显示该区域共检测出浮游植物7个门类,其中蓝藻门、硅藻门、绿藻门、隐藻门为优势类群。2018—2020年浮游植物年均密度分别为1.96×10⁶、2.55×10⁶和5.07×10⁶ cells/L,呈现出逐年增高趋势。浮游植物季度密度表现为秋季>夏季>春季>冬季,在夏秋季节蓝藻门和绿藻门占优势,春冬季节硅藻门和隐藻门占优势,同时硅藻门在四季中均占据生长优势。空间上库区浮游植物密度明显高于支流,且汉江库区浮游植物密度高于丹江库区,其中蓝藻门和绿藻门主要在库区大量出现,而支流则以硅藻门和隐藻门为主。RDA分析显示,影响丹江口水库浮游植物的主要环境因子是水温,其次为化学需氧量、氨氮和总磷。在不同季节和...  相似文献   

三峡澎溪河水-气界面温室气体模型估算及其敏感性分析   总被引：2，自引：0，他引：2  

赫斌  李哲  姚骁  郭劲松  陈永柏  李翀 《湖泊科学》2017,29(3):705-712

模型估算法是水-气界面温室气体通量监测的主要方法,所得成果也不胜枚举.然而监测过程中诸多环境因素会对最终结果产生不确定的影响.结合三峡库区澎溪河背景条件,利用模型估算法进行水-气界面温室气体通量(以CO_2为例)估算,并且采用修正Morris筛选法尝试分析模型估算法中各个参数对温室气体扩散通量(以CO_2为例)的局部敏感性.研究结果表明:利用模型估算法计算三峡澎溪河流域水-气界面温室气体通量具有较高的可行性和可靠性;风速、水温以及pH值会对监测结果产生影响,且风速越强、水温越高、pH值越小,CO_2扩散通量就越大;pH值是高灵敏参数,风速和水温是灵敏参数.在三峡库区澎溪河监测过程中更应注意pH值的精确性,每次采样前需校正仪器.  相似文献   

A Simplified Solution Using Izbash's Equation for Non-Darcian Flow in a Constant Rate Pumping Test     

Liang Xiao  Ming Ye  Yongxin Xu  Fuwan Gan 《Ground water》2019,57(6):962-968

This paper derives an equivalent of Darcian Theis solution for non-Darcian flow induced by constant rate pumping of a well in a confined aquifer. The derivation, which is valid at later times only, is original. It utilizes Izbash's equation. This introduces an additional parameter to Darcian condition, namely, empirical exponent. The solution is a non-Drcian equivalent of Jacob straight line method for analyzing pumping tests at late times. It can be used to determine aquifer parameters: storativity, analogous hydraulic conductivity, and empirical exponent. However, while the Jacob method requires a minimum of only one pumping test with one observation well, the additional parameter in the present solution means that a minimum of two observation wells in one test or two pumping tests at different rates with one observation well are required. The derived solution is applied to a case study at Plomeur in Brittany, France, and is shown to provide a practical and efficient method for analyzing pumping tests where non-Darcian groundwater flow occurs.  相似文献   

Ediacaran integrative stratigraphy and timescale of China     

Zhou  Chuanming  Yuan  Xunlai  Xiao  Shuhai  Chen  Zhe  Hua  Hong 《中国科学:地球科学(英文版)》2019,62(1):7-24

Ediacaran successions occur widely in various depositional facies in South China and yield a series of fossil Lagerst?tten, providing a complete fossil record for the evolution of marine ecosystems after the terminal Cryogenian global glaciation. Carbonate-dominated Ediacaran successions in shallow water facies in South China record a nearly complete δ~(13)C profile that may reflect variations of marine carbon isotopic composition during the Ediacaran Period. The Ediacaran fossils andδ~(13)C profiles from South China permit stratigraphic correlation and subdivision of the Ediacaran strata. Based on biostratigraphic, chemostratigraphic, and geochronometric data from the Ediacaran successions in South China, we propose that the Ediacaran System in China can be subdivided into two series, with three stages in each series. The lower series is characterized by acanthomorphic acritarchs and the upper series by Ediacara-type macrofossils, and the two series are separated by the declining limb of a pronounced δ~(13)C negative excursion(EN3) in the upper Doushantuo Formation. The basal boundary of Stage1 is the same as the basal boundary of Ediacaran System, which has been defined at the base of the cap carbonate unit. Stage 2 represents the first radiation of Ediacaran microscopic organisms, with δ~(13)C feature representing by positive values(EP1). The base of the Stage 2 is placed at the first appearance level of a spiny acritarch species. Stage 3 is characterized by the occurrence of more diverse acritarchs and δ~(13)C feature EP2, with its basal boundary defined by a δ~(13)C negative excursion(EN2) occurring in the middle Doushantuo Formation. The basal boundary of Stage 4 is the same as the upper series. Stage 5 is marked by the occurrence of macrfossils of Miaohe biota, and its lower boundary can be placed at the level where δ~(13)C values transition from positive to negative in MNE, or the first appearance level of macrofossils of the Miaohe biota. Stage 6 is characterized by the occurrences of Ediacara-type Shibantan biota and Gaojiashan biota, with its lower boundary defined by the first appearance level of Conotubus hemiannulatus. The formal establishment of the aforementioned series and stages requires further and more detailed integrative stratigraphic study on the Ediacaran successions in China. Some of the Ediacaran successions in South China have great potential to become global standards in Ediacaran subdivision.  相似文献   

Alleviating the Cadmium Toxicity and Growth‐Promotion in Paddy Rice by Photosynthetic Bacteria     

Xian Xiao  Yuan Zhao  Qin Zhou  Leyang Wang  Xujie Zhang  Lihua Zhao  Sheng Zhang 《洁净——土壤、空气、水》2019,47(3)

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Methane Oxidation in the Water Column of Xiangxi Bay,Three Gorges Reservoir     

Dan Lei  Jia Liu  Junwei Zhang  Andreas Lorke  Shangbin Xiao  Yuchun Wang  Wei Wang  Ye Li 《洁净——土壤、空气、水》2019,47(9)

Four field campaigns are carried out to quantify the methane (CH₄) oxidation rate in Xiangxi Bay (XXB) of the Three Gorges Reservoir (TGR), China. The water depth of the sampling site varied from 13 to 30 m resulting from the water level fluctuation of the TGR. The CH₄ oxidation rates are measured in situ as the decline of dissolved CH₄ concentration versus time in incubated, and those rates. The CH₄ oxidation rates range from 1.18 × 10^?3 to 3.69 × 10^?3 µmol L^?1 h^?1, with higher values and stronger variation during summer. A static floating chamber method is used to measure CH₄ emitted to the atmosphere resulting in an annual mean flux of 4.79 µmol m^?2 h^?1. The CH₄ emission rate is significantly negatively correlated with the water level. The results show that a large fraction of CH₄ is consumed in the water column with a range of 28.97–55.90 µmol m^?2 h^?1, accounting for ≈69–98% of the total CH₄ input into the water column, and more than 90% is consumed outside the summer, when the water level is lowest. Water depth, which is dominated by water level of the TGR, is a potentially important driver for CH₄ oxidation and atmospheric emission in the tributary bay.  相似文献