共查询到20条相似文献，搜索用时 46 毫秒
1.
小波变换在遥感图像压缩中的应用及Matlab实现 总被引：6，自引：2，他引：6
遥感图像在地理信息系统中的应用越来越广，但遥感图像所含的数据量较大。为了方便快速地实现遥感图像的浏览，必须对图像进行压缩。可基于离散小波变换的二维小波分析，采用对遥感图像进行压缩并结合MATLAB来实现。 相似文献
2.
一种基于粗糙集分类的图像压缩方法 总被引：2，自引：1，他引：2
作者在文中提出了一种基于粗糙集分类的智能图像压缩方法，图像子块经过DCT变换、特征属性提取后，再利用粗糙集将DCT域图像子块分为平坦块和边缘块两类，并针对不同的子块类别分别应用不同的SOFM神经网络进行矢量量化，最终实现对图像的有效压缩。实验结果表明，该方法压缩比高，信噪比高，信道误码率低，解码速度快，图像恢复效果好。 相似文献
3.
Shi Jiancheng 《第四纪研究》2012,32(1)
积雪覆盖(snow cover)是气候、水文和生态环境等研究领域中很重要的参数之一.与积雪覆盖二值技术不同,亚像元雪盖反演技术可以在给定卫星观测空间分辨率前提下进一步提高积雪覆盖面积的反演精度.“多端元光谱混合分析”方法反演亚像元积雪覆盖度具有物理意义明确、精度高等优势.但由于其需要通过端元选取、最小二乘法反演等计算,运行效率较低,难以满足大数据量计算.我们发展了一种改进“多端元光谱混合分析”方法反演MODIS亚像元积雪覆盖的算法.该算法通过对MOD09GA数据进行图像端元自动提取,并利用能够代表图像端元类的典型端元库进行“多端元光谱混合分析”反演亚像元积雪覆盖.我们在端元选取、多端元线性混合模型分解等方面进行了改进与发展,不仅保证了产品精度,同时提高了计算的时效性. 相似文献
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为了分析研究南宁盆地泥岩的压缩特性及规律,通过对泥岩的固结压缩试验,得到不同风化程度泥岩在同一压力条件下和同一风化程度泥岩在不同压力条件下的固结压缩性指标。利用数理统计方法,对试验压缩性指标按散点图分布规律进行函数曲线拟合,得出相关经验公式,从而分析研究压缩指标的特性及变化规律,为工程建设地基变形计算提供理论及数据支撑。 相似文献
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Two Dimensional Principal Analysis是新近提出的一种图像分析方法,并已在特征提取与人脸和物体识别中得到较好应用.由于2DPCA本身就具有数据压缩功能,在用于去除图像的空间相关性中,可实现对数据的压缩,尤其是对高光谱或多光谱遥感图像的压缩.实验结果表明,这类方法不仅有效,而且压缩性能良好. 相似文献
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边界单元法是磁场曲化平的一种原理简单而实用的数值计算方法,但该方法在处理大数据量的实际资料时,主要的困难是要求解一个大型、高阶的方程组,且边界值误差较大.对大型、高阶的方程利用小波压缩算法进行压缩和降阶处理,能节省时间和计算机内存,从而提高效率并发挥计算机的潜能.在保证足够精度的前提下,可以获得45%以上的压缩比.通过模型计算表明,该方法是可行的,能高效、精确处理磁场曲化平问题. 相似文献
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利用可同步进行CT扫描的三轴仪,进行了不同围压下的三轴压缩试验。通过CT图像对分层击实重塑土压缩过程中微裂纹产生的过程及力学机制进行了探讨,得到了一些有益的结论。 相似文献
9.
随着社会的发展,各类干扰日益加剧,高质量的大地电磁采集也变得愈加困难。为了提高数据质量,学者们针对不同类型的噪声提出了很多对应的去噪方法,由于大地电磁数据量都比较大,去噪前不可能对每条数据进行人工判读,急需一种高效率的噪声识别和分类方法。基于此,本文将人工神经网络应用于大地电磁时间序列分类中,为了选取最为合适的大地电磁时间序列分类网络模型,使用模拟方波、工频、脉冲噪声以及实测无噪声数据4类时间序列类型,分别对LSTM、FCN、ResNet、LSTM-FCN及LSTM-ResNet模型进行了噪声分类训练和实测数据分类对比试验。结果表明,FCN及LSTM-FCN在大地电磁时序分类中具有相对较好的效果。其中,FCN模型对实测数据分类准确率最高可达99.84%,每个epoch平均用时9.6 s, LSTM-FCN较FCN具有更高的分类精度,实测数据集最高分类准确率近乎100%,但是其每个epoch平均用时24.6 s,且较FCN也更易过拟合。总体来看,如果数据量较少使用LSTM-FCN可以获取更高的分类精度,数据量较大时需考虑时间成本,使用FCN则更为合适。最后,利用LSTM-FCN分类模型和... 相似文献
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基于图像检索技术的岩石单轴压缩破坏过程CT描述 总被引：1，自引：0，他引：1
基于X射线的CT扫描技术,因其具有多层位、对同一岩石试件可连续、无损扫描等优点,在岩石力学与工程研究中得到了广泛应用。对岩石单轴压缩破坏过程进行实时CT扫描,也是岩石力学研究的重要内容之一。针对三维显微CT试验系统实时监测煤岩单轴压缩破坏过程中,因位移误差会引起扫描层定位不准确,进而影响试验结果这一基本问题,提出了基于图像检索技术的CT扫描图像处理方法。通过对煤岩试样在单轴载荷作用下破坏过程的CT实时监测,并引入基于Manhattan距离的相似性计算方法,检索出岩石试件同一层位在不同应力状态下的相似扫描层。结果表明,采用图像检索的方法,可以有效地减小煤岩在加载破坏过程中位移误差的影响,更好地通过CT图像来描述煤岩在不同应力状态下的微裂纹分布状况和演化规律,从而在细观层次上揭示岩石在单轴压缩条件下破坏的基本规律。 相似文献
11.
Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
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Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414. 相似文献
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species. 相似文献
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Muriel Rocher Stéphane Baize Stéphane Jaillet Edward Marc Cushing Yannick Lozac&#x;h Francis Lemeille 《Comptes Rendus Geoscience》2003,335(8):701-708
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003). 相似文献
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正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.) 相似文献
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正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology, 相似文献
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正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.) 相似文献
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正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se- 相似文献
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正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with 相似文献