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21.
分析了构建速度场的统计模型和函数模型法,提出利用两种模型逼近原始观测速度的综合逼近法,以减少剩余误差.计算和比较了各种方法,结果显示,综合法优于单独利用统计模型和函数模型法. 相似文献
22.
Maowen Li Yongqiang Xiong Lloyd R. Snowdon Dale Issler 《Journal of Geochemical Exploration》2006,89(1-3):214
Molecular and isotopic compositions of crude oils in the Beaufort–Mackenzie Basin confirm three genetic end-member oil groups and suggest extensive cross-formational hydrocarbon fluid flows in the Tertiary deltaic system. Inter- and intra-fractional variations in the geochemistry of the Tertiary-reservoired oils indicate that the oil source/maturity signatures were substantially masked by biomarkers that were picked up along migration pathways. Thus, many of the previously recognized “immature non-marine oils” are in fact thermally mature, probably derived from unpenetrated deeper marine source rocks. Although the effective source rock volumes have not been evaluated and their exact stratigraphic levels remain unknown, the relative timing of oil generation versus trap formation, rather than poor source quality, may be the cause of under-filled traps in the offshore area. 相似文献
23.
Qiang Wang Derek A. Wyman Ji-Feng Xu Zhen-Hua Zhao Ping Jian Xiao-Lin Xiong Zhi-Wei Bao Chao-Feng Li Zheng-Hua Bai 《Lithos》2006,89(3-4):424-446
Both adakitic and shoshonitic igneous rocks in the Luzong area, Anhui Province, eastern China are associated with Cretaceous Cu–Au mineralization. The Shaxi quartz diorite porphyrites exhibit adakite-like geochemical features, such as light rare earth element (LREE) enrichment, heavy REE (HREE) depletion, high Al2O3, MgO, Sr, Sr / Y and La / Yb values, and low Y and Yb contents. They have low εNd(t) values (− 3.46 to − 6.28) and high (87Sr / 86Sr)i ratios (0.7051–0.7057). Sensitive High-Resolution Ion Microprobe (SHRIMP) zircon analyses indicate a crystallization age of 136 ± 3 Ma for the adakitic rocks. Most volcanic rocks and the majority of monzonites and syenites in the Luzong area are K-rich (or shoshonitic) and were also produced during the Cretaceous (140–125 Ma). They are enriched in LREE and large-ion lithophile elements, and depleted in Ti, and Nb and Ba and exhibit relatively lower εNd(t) values ranging from − 4.65 to − 7.03 and relatively higher (87Sr / 86Sr)i ratios varying between 0.7057 and 0.7062. The shoshonitic and adakitic rocks in the Luzong area have similar Pb isotopic compositions (206Pb / 204Pb = 17.90–18.83, 207Pb / 204Pb = 15.45–15.62 and 208Pb / 204Pb = 38.07–38.80). Geological data from the Luzong area suggest that the Cretaceous igneous rocks are distributed along NE fault zones (e.g., Tanlu and Yangtze River fault zones) in eastern China and were likely formed in an extensional setting within the Yangtze Block. The Shaxi adakitic rocks were probably derived by the partial melting of delaminated lower crust at pressures equivalent to crustal thickness of > 50 km (i.e., 1.5 GPa), possibly leaving rutile-bearing eclogitic residue. The shoshonitic magmas, in contrast, originated mainly from an enriched mantle metasomatized by subducted oceanic sediments. They underwent early high-pressure (> 1.5 GPa) fractional crystallization at the boundary between thickened (> 50 km) lower crust and lithospheric mantle and late low-pressure (< 1.5 GPa) fractional crystallization in the shallow (< 50 km) crust. The adakitic and shoshonitic rocks appear to be linked to an intra-continental extensional setting where partial melting of enriched mantle and delaminated lower crust was probably controlled by lithospheric thinning and upwelling of hot asthenosphere along NE fault zones (e.g., Tanlu and Yangtze River fault zones) in eastern China. Both the shoshonitic and adakitic magmas were fertile with respect to Cu–Au mineralization. 相似文献
24.
文中利用数据手套和跟踪器获取手臂各关节运动数据,根据关节运动限制对所获取数据进行处理,建立了符合人体运动规律的虚拟手臂数学模型,实现了虚拟环境中与试验者的手臂同步运动、效果逼真的虚拟手臂模型. 相似文献
25.
纹理映射是计算机图形学中广泛应用的一项重要技术,纹理图像可以描述景物表面各点处的反射属性,模拟景物表面丰富的纹理细节,减少建模的工作量,提高计算机生成图形的真实性.但是由于纹理都为栅格图像,放大和缩小会产生一定程度的失真,所以要对纹理进行细节分层处理.文中主要介绍纹理的重采样和建立金字塔技术,提出减少纹理映射失真的方法. 相似文献
26.
基于DEM的地形简化方法对比分析 总被引:4,自引:0,他引:4
地形简化作为一门重要的数据压缩技术已广泛应用于DEM。在大量简化算法中,地形简化指标作为地形简化的核心环节,其好坏直接关系到地形简化的好坏。本文对基于局部误差、曲率和法向量的五个地形简化指标进行了分析评价,用离散的高斯合成曲面来模拟真实DEM,以解析得到的高斯曲率作为地形简化指标“真值”,对比研究了在离散高斯曲面上得到的五个简化指标与解析所得“真值”,通过对各个指标“保特征性”可信度的分析,获得了对这五个指标的整体评价,最后,实例验证了本文结论的正确性。 相似文献
27.
本文主要讨论了利用空间投影一空间斜墨卡托(SOM)投影进行卫星遥感图像精纠正与定位,解决缺少控制点地区卫星遥感图像精纠正与定位问题,并根据正反算公式讨论了卫星遥感图像纠正的空间投影数学基础。 相似文献
28.
29.
库车坳陷位于塔里木盆地北部,北缘是南天山山前断裂带,南缘是塔北隆起,呈NEE向展布,东西长250km,南北宽20-60km,面积约21170km^2。下侏罗统自下而上发育阿合组、阳霞组。对吐格尔明、克孜勒努尔、库车河剖面及依南2井岩芯观察发现,阿合组和阳霞组按其岩性特征均可以划分为5个岩性段,各个岩性段在全具有对比性。还可分出4类和17个亚类岩相。阿合组细砂岩以上的粗碎屑岩含量为80%以上;阳霞组细砂岩以上的碎屑岩含量为50%-60%。砂岩厚度占总地层厚度的50%-60%以上,是油气勘探的重要目的层系。以吐格尔明剖面为代表的依南2井以东地区的阿合组和阳霞组岩矿特征基本相似,以克孜勒努尔地区为代表的依南2井以西地区有较大差异,即阳霞组长石含量几乎为零。两区共同点是以岩屑砂岩为主,成分成熟度低,结构成熟度中等,岩屑含量较高。从岩性组合、沉积构造、微观岩石成分、结构和砂体形态等方面的综合分析认为,辫状三角洲沉积体系是该区阿合组和阳霞组的主要沉积体系。阿合组砂体纵向上以多个辫状三角洲平原上的辫状分流河道砂岩加积复合为主,横向上指状镶嵌叠置呈东西向展布。阳霞组第3岩性段砂体纵向上以多个辫状三角洲前缘上的水下辫状分流河道砂岩加积复合为主,横向上指状镶嵌叠置也呈东西向展布。第2、4、5岩性段砂体以河道滞流砂岩侧砂为主,横向叠瓦状叠置呈东西向展布。 相似文献
30.
The response of low‐ductility reinforced concrete (RC) frames, designed typically for a non‐seismic region, subjected to two frequencies of base excitations is studied. Five half‐scaled, two‐bay, two‐storey, RC frames, each approximately 5 m wide by 3.3 m high, were subjected to both horizontal and/or vertical base excitations with a frequency of 40 Hz as well as a lower frequency of about 4 Hz (close to the fundamental frequency) using a shake table. The imposed acceleration amplitude ranged from 0.2 to 1.2g. The test results showed that the response characteristics of the structures differed under high‐ and low‐frequency excitations. The frames were able to sustain high‐frequency excitations without damage but were inadequate for low‐frequency excitations, even though the frames exhibited some ductility. Linear‐elastic time‐history analysis can predict reasonably well the structural response under high‐frequency excitations. As the frames were not designed for seismic loads, the reinforcement detailing may not have been adequate, based on the crack pattern observed. The effect of vertical excitation can cause significant additional forces in the columns and moment reversals in the beams. The ‘strong‐column, weak‐beam’ approach for lateral load RC frame design is supported by experimental observations. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献