在CepheusE中C~(18)O(J=1-0)分子外流的不准直性和速度成分     

俞志尧 《中国天文和天体物理学报》1999,(1)

分析ＣｅｐｈｅｕｓＥ中Ｃ１８Ｏ（Ｊ＝１－０）的速度位置图,发现相对于峰速度的红移速度成分主要分布在中心位置附近的核区,而相对于峰速度的蓝移速度成分除了分布在中心位置附近的核区外,还可以在向东和向西北方向的外流中找到。这说明强度分布图中的分子外流的不准直分布是由相对于峰速度的蓝移速度成分的不准直分布所引起的。  相似文献   

石笋微层物质组成的二次离子质谱初步分析及其气候意义   总被引：17，自引：2，他引：15       下载免费PDF全文

王先锋  刘东生  梁汉东  谭明  秦小光  周强 《第四纪研究》1999,19(1):59-66,T002

我国北方洞穴石笋中发育双重光性微层(透光微层和发光微层),两种微层可以相互对应,但也存在不相匹配的现象。运用二次离子质谱分析微层内物质组分,发现透光微层的浅色段含有相对丰度较高的Mg和Sr元素以及小分子有机质,而Ba和Fe及大分子有机质主要赋存于微层内暗色段,层内暗色物质包含有机质和粘土物质。微层物质组成和成因等方面的研究可以反映气候变化的高分辨率信息。  相似文献   

Numerical experiments on the Rayleigh-Ritz method when applied to doubly connected plates in the case of free edge holes     

P. A. A. Laura  D. R. Avalos  H. A. Larrondo  R. E. Rossi 《Ocean Engineering》1998,25(7)

Numerical experiments are performed on the determination of the fundamental frequency of transverse vibration of simply supported rectangular plates having rectangular holes with free edges. This constitutes a rather common technological situation since holes are present in plates or slabs due to operational conditions, namely passage of conduits or ducts, electric conductors, etc., Satisfying exactly the governing natural boundary conditions at the hole edges is practically an impossible task. This study reviews numerical experiments where the displacement function is expanded into a double Fourier series which constitutes the exact solution when the plate is simply connected. Satisfactory convergence is achieved when the plate is doubly connected.  相似文献   

珠江三角洲的水位变化趋势及其本征模型   总被引：2，自引：0，他引：2  

杨清书 《海洋科学》1998,22(1):47-51

根据一元线性回归分析的正则方程计算了高频扰动对确定海平面变化趋势的确切影响。结果表明 ,在验潮记录较短的客观条件下 ,高频扰动对趋势项的影响是显著的 ,其中影响最显著的高频带是 f≥ 0 .0 2 0 8cpm ( circle per month) ,即对应的周期 T≤ 4 a的高频扰动。探讨用最平滤波器对月均验潮序列进行低通数字滤波预消除高频扰动的影响 ,由低通序列一元线性回归分析来估算珠江三角洲各站近 30 a来的水位变化率。应用经验正交函数( EOF)分析珠江三角洲水位变化的时空特征及计算其区域水位变化趋势 ,EOF分解表明 ,珠江三角洲水位变化总体呈上升趋势 ,区域水位的平均变化率为 2 .3mm/ a。  相似文献   

HEIFE非均匀陆面上区域能量平衡研究   总被引：8，自引：1，他引：7  

马耀明  王介民  Massimo Menenti  Wim Bastiaanssen 《气候与环境研究》1997,2(3):293-301

卫星遥感在研究非均匀陆面上地－气间能量和水循环过程时有其独到的作用。本文介绍了一种利用陆地资源卫星ＴＭ资料进行非均匀陆面上区域能量平衡研究的参数化方案。以两个景的ＴＭ资料（１９９１年７月９日,夏季;１９９１年１０月２９日,近冬季）为个例,结合“黑河实验”（ＨＥＩＦＥ）期间的地面观测资料分析研究了实验区非均匀陆面上地表特征参数（地表反射率、标准化差值植被指数和地表温度）及能量平衡各分量（地表净辐射通量、土壤热通量、感热和潜热通量）的区域分布及季节差异,同时将所得的结果与地面观测的“真值”作了比较。结果表明：（１）由于黑河实验区下垫面状况十分复杂,戈壁、沙漠与绿洲交错分布,故在整个实验区内各地表特征参数及能量平衡各分量的分布范围亦比较宽;（２）地表特征参数及能量平衡各分量在实验区的绿洲、戈壁及沙漠上各有其特定的代表值;（３）地表能量平衡各分量的区域平均值在整个实验区内基本平衡;（４）夏季与近冬季的地表特征参数及能量平衡各分量的分布特征存在着显著差异。所得的这些结果与地面观测的“真值”和局地研究的结论基本一致。这些分析对非均匀下垫面中尺度模式陆面过程参数化方案的建立以及模式预报效果的检验都具有不可缺少的重要意义。  相似文献   

The role of urban growth,climate change,and their interplay in altering runoff extremes   总被引：1，自引：0，他引：1       下载免费PDF全文

Elisa Arnone  Dario Pumo  Antonio Francipane  Goffredo La Loggia  Leonardo V. Noto 《水文研究》2018,32(12):1755-1770

Changes in climate and urban growth are the most influential factors affecting hydrological characteristics in urban and extra‐urban contexts. The assessment of the impacts of these changes on the extreme rainfall–runoff events may have important implications on urban and extra‐urban management policies against severe events, such as floods, and on the design of hydraulic infrastructures. Understanding the effects of the interaction between climate change and urban growth on the generation of runoff extremes is the main aim of this paper. We carried out a synthetic experiment on a river catchment of 64 km² to generate hourly runoff time series under different hypothetical scenarios. We imposed a growth of the percentage of urban coverage within the basin (from 1.5% to 25%), a rise in mean temperature of 2.6 °C, and an alternatively increase/decrease in mean annual precipitation of 25%; changes in mean annual precipitation were imposed following different schemes, either changing rainstorm frequency or rainstorm intensity. The modelling framework consists of a physically based distributed hydrological model, which simulates fast and slow mechanisms of runoff generation directly connected with the impervious areas, a land‐use change model, and a weather generator. The results indicate that the peaks over threshold and the hourly annual peaks, used as hydrological indicators, are very sensitive to the rainstorm intensity. Moreover, the effects of climate changes dominate on those of urban growth determining an exacerbation of the fast runoff component in extreme events and a reduction of the slow and deep runoff component, thus limiting changes in the overall runoff.  相似文献   

基于ArcObjects组件的地理数据检查软件的实现     

朱旭红  许国安  陈咬根 《测绘工程》2010,19(2):49-52

基础地理数据的质量好坏直接关系到其他相关信息系统的应用,直接影响着整个信息系统的可信度。结合宁波市鄞州区基础地理数据入库工程实例,叙述基于ArcObjects组件建立地理数据检查软件的原理、方法和实现功能过程。实践证明,通过这种方法能使地理数据的准确性、可靠性和一致性得到极大地保证。  相似文献   

基于散射分量系数的极化SAR数据分类     

杨然  李坤  秦前清 《测绘信息与工程》2010,35(3):23-25

分析了传统的基于散射功率大小的极化SAR数据分类算法,提出了一种基于散射分量系数的改进算法,实现了全极化SAR数据的有效性分类。  相似文献   

基于构造与蚀变信息的找矿方法初探   总被引：1，自引：0，他引：1  

夏福瑞  何政伟  许辉熙  薛万蓉 《测绘科学》2010,35(3):46-48

遥感图像蚀变信息的提取是遥感地质找矿的一个重要方法,地质构造信息作为一种指示信息对找矿也具有非常重要的意义。本文利用Landsat7 ETM+卫星影像数据,通过主成分分析方法和阈值分割技术对新疆叶城县麻扎一带进行了铁化及泥化蚀变信息的提取,并结合研究区线性、环形构造的特点,对研究区进行成矿预测,创新利用比值方法剔除伪信息,圈定找矿远景区。此工作方法效果明显,为今后加快地质找矿工作提供了一条可参考、行之有效的途径。  相似文献   

Component flow processes at four streams in the Catskill Mountains,New York,analysed using episodic concentration/discharge relationships     

C. Evans  T. D. Davies  P. S. Murdoch 《水文研究》1999,13(4):563-575

Plots of solute concentration against discharge have been used to relate stream hydrochemical variations to processes of flow generation, using data collected at four streams in the Catskill Mountains, New York, during the Episodic Response Project of the US Environmental Protection Agency. Results suggest that a two‐component system of shallow and deep saturated subsurface flow, in which the two components respond simultaneously during hydrologic events, may be applicable to the study basins. Using a large natural sea‐salt sodium input as a tracer for precipitation, it is argued that an additional distinction can be made between pre‐event and event water travelling along the shallow subsurface flow path. Pre‐event water is thought to be displaced by infiltrating event water, which becomes dominant on the falling limb of the hydrograph. Where, as appears to be the case for sulfate, a solute equilibrates rapidly within the soil, the pre‐event–event water distinction is unimportant. However, for some solutes there are clear and consistent compositional differences between water from the two sources, evident as a hysteresis loop in concentration–discharge plots. Nitrate and acidity, in particular, appear to be elevated in event water following percolation through the organic horizon. Consequently, the most acidic, high nitrate conditions during an episode generally occur after peak discharge. A simple conceptual model of episode runoff generation is presented on the basis of these results. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献