机载干涉SARDEM绝对定向技术研究     

王宁娜  黄国满  杨本勇  杨书成  赵争 《测绘科学》2012,(1):32-34

机载干涉SAR产生的未经地理编码的DEM有较高的相对高程精度,但因其是基于斜距表达的,且干涉几何定标存在误差,需要利用控制点来进行绝对定向。本文首先改正由地形起伏引起的像点位移,将斜距DEM转换成地距DEM,然后根据空间相似变换,将地距DEM视为刚体,利用控制点求模型平移偏量、缩放因子及旋转角,达到绝对定向的目的。  相似文献   

南极长城湾夏季叶绿素a变化的研究   总被引：3，自引：1，他引：2       下载免费PDF全文

朱明远  李宝华  黄凤鹏  陈皓文 《极地研究》1999,11(2):36-44

１９９２年１２月～１９９３年３月、１９９３年１２月～１９９４年２月、１９９４年１２月／１９９５年３月连续３个夏季期间在南极长城湾进行了海洋生态系统调查,利用获得的浮游植物现存量（叶绿素ａ）资料进行分析研究发现：１９９２／１９９３年夏季叶绿素ａ含量最高,平均值为３．７９ｍｇ／ｍ３,变化幅度也最大,为１０．１０ｍｇ／ｍ３。连续３个夏季的年际变化趋势是３．７９ｍｇ／ｍ３（１９９２／１９９３）＞１．８０ｍｇ／ｍ３（１９９３／１９９４）＞１．２０ｍｇ／ｍ３（１９９４／１９９５）。而变化的幅度也同样依次为１０．１０ｍｇ／ｍ３＞６．５７ｍｇ／ｍ３＞２．４１ｍｇ／ｍ３。所获得的结果与南极地区相同季节其它近海海水中的叶绿素ａ含量进行比较得知：除Ｇｅｒｌａｃｈｅ海峡（１９５９年１月）１１．６０ｍｇ／ｍ３和ＭｃＭｕｒｄｏ海峡（１９６１年１２月）５６．１０ｍｇ／ｍ３外,这次调查结果属中上水平。本文还对该海域叶绿素ａ的垂直分布状况进行了分析。  相似文献   

建立适用于远程勘探的物探数据分析系统   总被引：1，自引：0，他引：1  

陈超 《物探与化探》1999,23(4):309-313,316

建立远程勘探系统是勘探领域发展的新趋势,远程勘探系统的核心组成应该是具有丰富内容的数据仓库(datawarehouse)和包含多领域数据分析与处理方法的工具库或方法库.针对勘探领域中的物探数据分析处理系统的技术构成和实现技术提出一些观点,对数据存取、分析方法库的构成、参数提取、图形显示技术及远程操作做了介绍,旨在提供此类系统的一种模式.  相似文献   

川西高原大雪人工神经元网络短期预报系统     

陈晓刚  郭斌  张政 《气象》1999,25(8):37-39

采用初级预报模式结合人工神经元网络（ＢＰ算法）的方法,使用阿坝牧区大雪天气过程历史资料,研制了川西高原牧区大雪天气预报系统。利用９２１０工程接收到的数据资料,自动完成因子采集和结论输出,每次输出后,因子库自动增加新的因子,网络再次学习,从而进一步提高预报精度。  相似文献   

青藏高原热力状况与四川盆地汛期降水的联系   总被引：24，自引：9，他引：15  

叶月珍  方之芳 《高原气象》1999,18(2):162-170

应用高原积雪日数和高原气温、四川盆地逐月降水量资料,应用ＳＶＤ等方法,探讨高原热力状况分布异常与四川盆地汛期降水分布的联系。分析结果表明,高原积雪日数场分布特征是以巴颜喀拉山和念青唐古拉山为中心。该区域冬季积雪日数异常与川中盆地汛期干旱有相当好的联系。春季青藏高原北部和祁连山的温度场的大范围异常则与川西的洪涝和川东的干旱均有较好的相关,均可作为四川降水长期预报综合考虑的重要参考因子。一般而言,积雪  相似文献   

短期气候预测的多时间序列相空间相似模型   总被引：3，自引：0，他引：3  

尤卫红  李敏  段旭 《南京气象学院学报》1999,22(3):392-397

为了充分利用对气候系统进行定时观测而积累的关于它过去和现在情况的大量数据,本文提出了短期气候预测的一种多时间序列相空间相似模型,并从与云南气候变化有某种物理关系的２０多个时间序列出发,建立了一个云南短期气候变化的年度预测模型。模型对云南８０个气象观测站点１９９１～１９９８年的５月雨量距平和５月气温距平预测检验的距平同号率分别达到４２４／６４０＝ ６６．３％ 和４２６／６４０＝ ６６．６％ ;对云南１９９０～１９９７年的６～８月雨量距平、６～８月气温距平、年雨量距平和年气温距平预测检验的距平同号率则可分别达到４０４／６４０＝ ６３．１％ 、４６３／６４０＝ ７２．３％ 、４５６／６４０＝ ７１．３％ 和４５５／６４０＝ ７１．１％ 。  相似文献   

T63 月延伸预报在西南区域短期气候预测中的应用研究   总被引：14，自引：4，他引：10  

马振锋  陈洪 《应用气象学报》1999,10(3):368-373

利用国家气候中心1996、1997年1~12月T63模式所作的500 hPa　70次月延伸预报产品和1966~1996年ECMWF的500 hPa旬平均高度场以及西南区域月气温和月雨量场资料,建立了用T63动力产品预测西南区域月要素场的一种完全预报（PP）的动力-统计关系。并对西南区域1996年2月至1998年1月逐月气温和降水进行了预报试验。结果表明,这种利用动力延伸集合预报产品制作西南区域月要素场预报的动力与统计相结合的释用方法具有明显的预报能力。  相似文献   

华南区域短期气候模式产品时间过滤方案及实例分析   总被引：1，自引：1，他引：0  

阎敬华 《热带气象学报》1999,15(3):213-220

用尺度分离方法分析了短期气候预测序列中所包含的各种尺度的过程,建立了不同尺度变化的过滤、提取方法;分析讨论了各种过滤序列所具有的气候意义和重要程度;用模拟实例分析了所提出和使用的尺度分离方法的有效性及模式的性能  相似文献   

A spatial assessment of hydrologic alteration caused by dam construction in the middle and lower Yellow River,China   总被引：5，自引：0，他引：5  

Tao Yang  Qiang Zhang  Yongqin David Chen  Xin Tao  Chong‐yu Xu  Xi Chen 《水文研究》2008,22(18):3829-3843

The ‘range of variability approach’ (RVA) and mapping technique are used to investigate the spatial variability of hydrologic alterations (HA) due to dam construction along the middle and lower Yellow River, China, over the past five decades. The impacts of climate variability on hydrological process have been removed during wet and dry periods and the focus is on the impacts of human activities, such as dam construction, on hydrological processes. Results indicate the following: (1) The impacts of the Sanmenxia reservoir on the hydrologic alteration are relatively slight with a mean HA value of 0·48, ranking in the last place among the four large reservoirs. (2) Xiaolangdi reservoir has significantly changed the natural flow regime downstream with mean HA value of 0·56, ranking it in first place among the large reservoirs. (3) The results of ranked median degrees of 33 hydrologic alteration indicators for 10 stations in the Yellow River show that the hydrologic alteration of Huayuankou ranks the highest among 10 stream gauges. (4) Impacts of reservoirs on hydrological processes downstream of the dams are closely associated with the regulating activities of the reservoirs. At the same time, alterations of streamflow regimes resulting from climatic changes (e.g. precipitation variability) make the situation more complicated and more hydrological observations will be necessary for further analysis. The results of the current study will be greatly beneficial to the regional water resources management and restoration of eco‐environmental systems in the middle and lower Yellow River characterized by intensified dam construction under a changing environment. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Hybrid simulation: An early history     

Masayoshi Nakashima 《地震工程与结构动力学》2020,49(10):949-962

This historical note reports on the early days of the development of an experimental method called “hybrid simulation.” As background, the seeds of this concept, initiated in the early 1970s by Japanese researchers, are presented first, followed by initial efforts (regarded as Stage I) to realize the concept of hybrid simulation and its first applications to explore the seismic performance of structures. The initial research in this now-seminal field of earthquake engineering began in the early 1970s by Koichi Takanashi and his coworkers at the Institute of Industrial Science, the University of Tokyo. Their highly notable efforts in laying the groundwork for hybrid simulation occurred in the mid-1970s through the early 1980s by Takanashi (for steel structures) and Tsuneo Okada (for RC structures). These two men and their coworkers first applied hybrid simulation to explore the seismic behavior, performance, and design of various types of building structures. In Stage I, this method was called “the on-line computer-controlled test” or “pseudo dynamic test” because the unique feature of the method was the combined test and simulation and the intentional slow loading in the test. Extension of the scope and application of hybrid simulation occurred largely between the early 1980s and the early 1990s (regarded as Stage II) in conjunction with the United States–Japan joint research project. A few notable efforts made around that period are touched upon briefly, including error propagation and suppression in multi-degree-of-freedom hybrid simulation, application of the substructure methodology to hybrid simulation, and real-time hybrid simulation.  相似文献