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991.
介绍了2006年上海天文台卫星激光测距观测和系统改造情况。 相似文献
992.
B???????о????????????,????????b???????′???????????,?????b??????????????b??????????(????С???????????,????Χ,С???С????????????????????)?????????,????????????????b????????·?? 相似文献
993.
Liu K.Zhang J.-J.Ge M.-H.Ling Y.-Y. 《矿物岩石地球化学通报》2016,(6):1098-1108
The eastern pari of the Xing-Meng Orogenic Belt( XMOB )consists of the Lesser Xing'an-Zhangguangcai Range Orogenic belt, the Bureya-Jiamusi-khanka Block and the Sikhote-Alin accretionary belt. This area is located between the Paleo-Asian oceanic and Paleo-Pacific tectonic regimes. Recent researches imply that the Paleo-Pacific subduction might have begun since early Permian and influenced the both sides of the Mudanjiang Fault during Triassic, which generated a N-S trending magmatic belt and accretionary complexes, such as the Heilongjiang Complex. In Late Jurassic to Early Cretaceous, some tectono st rati graph ic terranes were produced in Sikhote-Alin, which were then dismembered and migrated northwards in late Early Cretaceous by sinistral strike-slip faults. The continental margin parallel transportion weakened subduction-related magmatism in NE China which was under an extensional setting. However, in Lite Cretaceous, the Paleo-Pacific subduction was re-Activated in the eastern XMOB, which contributed to the magmatism in Sikhote-Alin. 相似文献
994.
多基线数字近景摄影测量与传统近景摄影测量相比,具有短基线、大重叠度的特点,短基线使得相邻光束交会角较小,易于提高影像匹配精度;大重叠度使得首尾交会角较大,从而可提高空间点定位精度。该方法有效地解决了影像匹配、交会角和点定位精度三者之间存在的矛盾。首先,利用非量测数码相机进行多基线平行摄影,借助Lensphoto软件实现建筑物立面点坐标的量测,并将其与高精度莱卡全站仪测量结果进行精度对比,最后分析控制点个数与点位精度之间的关系。实验表明,多基线近景摄影测量在建筑工程测量中可以取得较高的点位精度,控制点个数的增加会提高点位精度,但存在一定极限。 相似文献
995.
Retracking altimeter waveforms over inland water bodies is a challenging task as a wide range of waveform is encountered while the retracking algorithms are available only for a handful of echo shapes. One such waveform shape widely encountered in lakes and reservoirs is the multipeak echo. These echoes are produced when the interacting surface in the altimeter footprint is not homogeneous and a number of different types of surfaces contribute to the resulting waveform. The widely used conventional retrackers, namely the Brown, Beta-5, Ice-2, OCOG, and threshold, can retrack a number of different waveform shapes such as the Brown like waveforms, specular waveforms, and rectangular waveforms but may not perform well for multipeak waveforms. In this article, a technique has been demonstrated to identify the different subwaveforms within a multipeak waveform and identify the subwaveform corresponding to the target at nadir. The subwaveform that is reflected from the nadir surface is identified from apriory information about the surface topography of the area. The subwaveform is then retracked using the 50% threshold to find the correct retracked range and water height. This technique has been tested for nine cycles of SARAL SIGDR data on Ukai reservoir, Gujarat, India, and found to perform much better than the other retrackers, particularly for multipeak waveforms. 相似文献
996.
华南海岸岬间海滩地形动力状态类型研究 总被引:1,自引:0,他引:1
海滩地形动力状态分类对于理解近岸带动形动力过程、海滩浴场风险评估等方面有重要的意义。收集了华南51个岬间海滩波高、波周期、潮差和泥沙粒径等地形动力要素特征值,利用分层聚类分析方法,同时结合海滩相对潮差分类模型,对华南岬间海滩的类型进行了探讨,结果表明:(1)华南岬间海滩可以聚类成7个类型。通过与相关的现场观测比较,各类型在地形组合上具有各自的显著特征;(2)聚类分析结果能很好的区分中到大潮差海岸与小潮差海滩之间的差异,与相对潮差模型结果一致。对于小潮差海滩,聚类结果与相对潮差模型有一定的差异,表明华南小潮差海滩的分类还需要进一步深入研究。 相似文献
997.
A long-term mark-recapture study was used to assess the movement patterns of surf-zone fishes in the St Lucia Marine Reserve, a marine protected area within the iSimangaliso Wetland Park, a World Heritage Site on the east coast of South Africa. Between 2001 and 2013, 6 613 fish from 71 species, caught by hook and line, were tagged at four sites within and adjacent to a no-take marine sanctuary area. A total of 1 004 (15.2%) recaptures were made from 17 species. The majority (82.4%) of these species displayed station-keeping behaviour, whereas only three were classified as wider-ranging species, and no species with discernible migratory behaviour was observed. Findings for five species with the highest recapture rates, namely Pomadasys furcatus, Epinephelus andersoni, E. marginatus, Dinoperca petersi and Lutjanus rivulatus, are presented in greater detail. Recapture rates ranged from 7% to 50% and time at liberty from 0 to 3 163 days. Individuals of all five species displayed station-keeping behaviour, with the 95th percentile of intra-study-site movements varying between 200 and 1 025 m (linear distance). However, four of the five species also displayed some ranging behaviour and made exploratory excursions ranging from 3.5 to 125 km, in both northerly and southerly directions. The dominance of station-keeping behaviour suggests that the St Lucia Marine Reserve sanctuary zone provides an important refuge for these species, with some export to adjacent areas. 相似文献
998.
柿竹园矿床成矿温度研究—以490中段为例 总被引:1,自引:0,他引:1
以490中段为例,根据硫同位素平衡温度、包裹体均一温度以及矿物温度确定主要成矿期各个阶段的温度范围:矽卡岩阶段温度为300~580℃,云英岩阶段温度为226~489℃,高—中温硫化物阶段温度为246~350℃,中—低温硫化物阶段温度为158~270℃。 相似文献
999.
1000.
星载SAR成像与SAR图像中一些不确定性因素分析 总被引:4,自引:0,他引:4
SAR成像中的不确定性因素不仅影响SAR成像质量,还给SAR图像的解译与应用带来困难。为了改善这些不确定性,从SAR成像的原理和过程出发,深入分析和探讨星载SAR成像与SAR图像中的多普勒参数估计、距离迁徙、斑点噪声和后向散射系数所产生的不确定性及带来的影响,并对部分不确定性提出相应的改善方法。利用实测ERS-2数据进行成像实验,实验结果显示SAR成像中的不确定性可以尽量得到改善,这对进一步研究SAR成像和应用有着实际意义。 相似文献