云的移动轨迹成像模拟及云量变化分析     

霍娟  吕达仁 《南京气象学院学报》2006,29(2):209-214

以全天空数字成像仪的等角投影成像原理为基础，将云型简化为正方体及圆柱体云体。模拟了相同云体在不同空间位置的移动轨迹情况，对其所占面积变化（云量）进行了计算，并对云在移动过程中云体侧面成像情况做了分析研究。结果表明，云量随空间位置变化情况与云的宽高比相关，当宽高比大于某一值时云量随天项角（云所处位置）的增大先增大而后减小，反之则随着天顶角的增大而减小。  相似文献   

气相色谱和原子发射光谱联用仪在石油馏分分析中的应用     

章炜  陈富强 《岩矿测试》1997,16(3):207-210

介绍了毛细管气相色谱和原子发射光谱联用仪（ＧＣ＿ＡＥＤ）在石油馏分分析中的几个应用实例。结果表明，利用ＧＣ＿ＡＥＤ的高选择性和高灵敏度，能够快速、有效地解决石油分析中的一些复杂问题，准确度、精密度满足应用要求。  相似文献   

地质样品中稀土总量的X射线荧光分析法测定   总被引：1，自引：0，他引：1  

梁述廷 《矿物岩石》1997,17(1):117-120

本文研究了稀土元素Ｃｅ的质量分数ｗＣｅ与由Ｃｅ至Ｌｕ１２元素质量分数之和ｗ１２（Ｎｄ除外）间的关系，发现ｗＣｅ和ｗ１２间存在明显一致的线性相关性。回归ｗ１２－ＩＣｅ标准工作曲线，实现了ｗ１２的直接测定。方法采用直接粉末压片制样，光谱仪测定ｗＣｅ，ｗＬａ，ｗＮｄ，ｗＹ，ｗ１２参数条件实现与稀土总量的转换。按本法对标准物质进行单项测定，结果令人满意  相似文献   

广西拉么Zn—Cu矿床中夕卡岩的主要矿物特点与Ca—Fe—Si—C—O体系T—lgfO2图解   总被引：1，自引：0，他引：1  

赵劲松 《矿物学报》1989,9(2):154-164

用电子探针数据研究了该矿床中主要夕卡岩矿物特点及其变化规律。采用理想结晶溶液固溶体位置混合模式,计算了石榴子石和辉石矿物对中钙铁榴石和钙铁辉石的摩尔分数。在计算纯固相和流体相参加的反应抵达平衡时的边界方程中,加上理想结晶固溶体中端元组分摩尔分数的修正项后,我们便可以计算出有纯固相、流体相和理想结晶溶液固溶体参加反应的在给定T、P条件下的lgfo_2值。计算结果表明:无变度点4周围的Hed+And+Wol组合对本矿区具有重要的地质地球化学意义。  相似文献   

Turbulence Structure in the Wake Region of a Meteorological Tower   总被引：2，自引：0，他引：2  

Christian Barthlott  Franz Fiedler 《Boundary-Layer Meteorology》2003,108(1):175-190

A meteorological tower significantly modifies the air flow, the mean windspeed and wind direction as well as the turbulencestructure of the air. Suchchanges can be noticed in particular in the wake region of the tower.Measurementson the 200 m tower ofForschungszentrum Karlsruhewere carried outusing Solent sonic anemometers in the lee of the towerand cup anemometers on both sides.In the wake region, spectral energydensity is increased in the high-frequency range. Superposition of this disturbance spectrum on the undisturbedspectrum yields a `knee' in the resulting spectrum. In the case of low turbulence intensity with stable stratification,a plateau with a constant energy content is observed in front of the knee.This effect is caused by the new production of turbulence energy from the mean flow as well as by an energy transfer fromlarger to smaller vortices. Power spectra in strongly stable conditionsshow a more rapid decrease of intensity in the region where the inertialsubrange is expected.The relevant scales of wake turbulence are derived from the maximum of the disturbance spectrum.Locations of the high-frequency peak do not depend on atmospheric stability,but are controlled mainly by mean wind speed.Apart from the reduction of the mean wind speed, the spectra and cospectra exhibit a strong anisotropy for such cases.The results demonstrate the significant influence of a tower on turbulence spectra in the wake region.  相似文献   

利用数值积分提高一维模型电偶源电磁测深响应计算精度   总被引：14，自引：4，他引：14       下载免费PDF全文

翁爱华  王雪秋 《地震工程学报》2003,25(3):193-197

讨论了直接利用数值积分提高电偶源电磁测深响应计算精度的方法．具体为对Hankel积分进行直接积分，结合连分式展开方法以提高积分求和的收敛速度．利用该方法对均匀半空间和层状(两层)模型的电磁测深响应进行了模拟，结果表明与常规的快速Hankel滤波方法相比，采用直接数值积分能明显提高电偶源频率测深响应计算精度．从而为获得高精度瞬变测深晚期响应提供算法基础．  相似文献   

上海城区建筑密度与地面沉降关系分析   总被引：26，自引：0，他引：26  

严学新  龚士良  曾正强  俞俊英  沈国平  汪铁骏 《水文地质工程地质》2002,29(6):21-25

工程建设逐渐成为上海近年来新的地面沉降制约因素，本文选择4个典型的高层建筑及多层建筑密集区段，分析了建筑密度与地面沉降的关系，探讨了其时空变化特征，建筑规模及其增长速度直接导致工程性地面沉降同步增长，集中建设较分散建设，新区建设较旧城改造、高层建筑较多层建筑地面沉降效应明显。建筑密度越大，建筑容积率越高，地面沉降越显著。城市规划宜选择低密度、低容积率的建设模式，降低建筑高度，扩大建筑间距。提出了沉降控制条件下适宜的建筑容积率应在0.9～1.2之间，从而为城市规划提供了决策性技术指标。  相似文献   

基于遥感的漳平市杉松林地表可燃物负荷量估测     

陈芸芝  陈崇成  汪小钦  唐丽玉 《地球信息科学学报》2007,9(6):103-135

 杉木林和马尾松是分布于漳平市的两种易燃的可燃物类型。其可燃物负荷量的多少决定着林火行为。在利用ASTER计算杉木林小班平均植被覆盖度的基础上估算其郁闭度,通过与地面调查结果比较分析,校正已发生明显变化的小班郁闭度。根据已有估测方程,结合小班数据中的年龄、胸径和树高等因子对杉木地表可燃物负荷量进行了估测,据此对各杉木小班的燃烧性、燃烧强度及火险等级等因素进行初步评价。最后对漳平市另一易燃的可燃物马尾松类型开展地表可燃物负荷量估测及分析。  相似文献   

Relationships between heavy metals and iron oxides,fulvic acids,particle size fractions in urban roadside soils     

Xue-Song Wang  Yong Qin 《Environmental Geology》2007,52(1):63-69

Urban roadside soils are the “recipients” of large amounts of heavy metals from a variety of sources including vehicle emissions, coal burning waste and other activities. The behavior of heavy metals in urban roadside soils depends on the occurrence as well as the total amount. Accordingly, knowledge of the interactions between heavy metals and other constituents in the soil is required to judge their environmental impact. In this study, correlations of heavy metal concentrations (Pb, Zn, Cu, Ag, Se, Ni, Cr and Ba) to iron extracted using dithionite–citrate–bicarbonate (DCB) buffer (Fe_DCB), fulvic acids and particle size fractions were examined from the Xuzhou urban roadside soils. Heavy metals except for Cr and fulvic acids had a positive significant correlation with Fe_DCB, indicating these metals and fulvic acids are principally associated with the surfaces of iron oxides of the soils. Significant positive correlations were also found between the contents of fulvic acids and heavy metals, showing these heavy metals (especially for Cu, Ni and Cr) form stable complexes with fulvic acids. Such finding is of importance with regard to the increased mobilization of heavy metals, e.g., into freshwater ecosystems. Ag, Se and Cr are independent of particle size fractions because of their low concentrations of Ag and Se in the studied soils. Pb, Zn, Cu, Ba and Ag are mainly enriched in the finer soil particles (especially <16 μm).  相似文献   

Seasonal characteristics of the Tsushima Current in the Tsushima/Korea Strait obtained by a fine-resolution numerical model     

Y.H. Seung  Y.-J. Kim  J.-H. Yoon 《Continental Shelf Research》2007

The horizontal distribution of the Tsushima Current in the Tsushima/Korea Strait is assessed by a fine-resolution numerical experiment. The comparison of the model results with the observations along a section crossing the strait shows that the model represents relatively well, the general tendency of what was observed, such as the separation of the Tsushima Current into the western and eastern streams by the Tsushima Island. In summer, strong and relatively uniformly distributed surface currents enhance the formation of the wake downstream of the Tsushima Island. The axis of the countercurrent, embedded in the wake, is closer to the western stream. Anti-cyclonic eddies are shed near the downstream tip of the Tsushima Island and propagate along the boundary between the western stream and the wake. The exchange of water between the western stream and the wake takes place through the intermediation of these eddies. There is a net water supply from the western stream to the wake, which is then carried to the eastern stream by the countercurrent via the eastern coast of the Tsushima Island. In winter, currents, strongly barotropic, tend to have banded structures, especially in the region downstream of the western channel where isobaths converge in the downstream direction. The eddies found in this region in winter appear to be fundamentally different from those associated with the Tsushima Island wake. The necessary condition for barotropic instability is satisfied for the monthly mean currents in this region, suggesting that the currents are barotropically unstable in this region in winter.  相似文献