同步辐射X射线荧光微探针测定岩石中的元素分布   总被引：10，自引：1，他引：10  

安庆骧  巢志瑜 《岩矿测试》1991,10(2):84-88

同步辐射X射线(白光)荧光微探针在大气环境下,光斑尺寸为(50×50)μm~2,位移为1mm/步,计数时间30s,扫描测量了含石榴石紫苏花岗岩中多元素(K、Ca、Ti、Cr、Mn、Fe、Cu、Zn、Rb和Sr)的分布并绘制成图。检测限达x×10ppm,绝对量为10~(-10)—10~(-11)g范围。  相似文献   

Stochastic overland flows     

R. S. govindaraju  M. L. Kavvas 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(2):89-104

A theoretical solution framework to the nonlinear stochastic partial differential equations (SPDE) of the kinematic wave and diffusion wave models of overland flows under stochastic inflows/outflows, stochastic surface roughness field and stochastic state of flows was obtained. This development was realized by means of an eigenfunction representation of the time-space overland flow depths, and by transforming the problem into the phase space. By using Van Kampen's lemma and the cumulant expansion theory of Kubo-Van Kampen-Fox, the deterministic partial differential equation (PDE) for the evolutionary probability density function (pdf) of overland flow depths was finally obtained. Once this deterministic PDE is solved for the time-varying pdf of overland flow depths, then the time-space varying pdf of overland flow depths can be obtained by a transformation given in the text. In this solution framework it is possible to incorporate the stochastic dynamic behavior of the parameters and of the forcing functions of the overland flow process. For example, not only the individual rainfall duration and fluctuating rain intensity characteristics but also the sequential behavior of rainfall patterns is incorporated into the evolutionary probability density function of overland flow depths.  相似文献   

Vertical distribution of dimethylsulfide,sulfur dioxide,aerosol ions,and radon over the Northeast Pacific Ocean     

M. O. Andreae  H. Berresheim  T. W. Andreae  M. A. Kritz  T. S. Bates  J. T. Merrill 《Journal of Atmospheric Chemistry》1988,6(1-2):149-173

Dimethylsulfide (DMS), sulfur dioxide (SO₂), methanesulfonate (MSA), nonsea-salt sulfate (nss-SO₄ ^2–), sodium (Na⁺), ammonium (NH₄ ⁺), and nitrate (NO₃ ^–) were determined in samples collected by aircraft over the open ocean in postfrontal maritime air masses off the northwest coast of the United States (3–12 May 1985). Measurements of radon daughter concentrations and isentropic trajectory calculations suggested that these air masses had been over the Pacific for 4–8 days since leaving the Asian continent. The DMS and MSA profiles showed very similar structures, with typical concentrations of 0.3–1.2 and 0.25–0.31 nmol m^–3 (STP) respectively in the mixed layer, decreasing to 0.01–0.12 and 0.03–0.13 nmol m^–3 (STP) at 3.6 km. These low atmospheric DMS concentrations are consistent with low levels of DMS measured in the surface waters of the northeastern Pacific during the study period.The atmospheric SO₂ concentrations always increased with altitude from <0.16–0.25 to 0.44–1.31 nmol m^–3 (STP). The nonsea-salt sulfate (ns-SO₄ ^2–) concentrations decreased with altitude in the boundary layer and increased again in the free troposphere. These data suggest that, at least under the conditions prevailing during our flights, the production of SO₂ and nss-SO₄ ^2– from DMS oxidation was significant only within the boundary layer and that transport from Asia dominated the sulfur cycle in the free troposphere. The existence of a sea-salt inversion layer was reflected in the profiles of those aerosol components, e.g., Na⁺ and NO₃ ^–, which were predominantly present as coarse particles. Our results show that long-range transport at mid-tropospheric levels plays an important role in determining the chemical composition of the atmosphere even in apparently remote northern hemispheric regions.  相似文献   

海洋底边界层中实测海流的垂直分布Ⅱ·潮流边界层     

乐肯堂  庄国文  宋金宝  侯一筠  朱兰部 《海洋与湖沼》2003,34(2):187-193

为了满足海洋工程设计的需要,作者从理论上研究了海底以上1－2m处潮流边界层的结构。把传统上用于稳定海流的底Ekman层理论发展成为用于潮流运动的振荡Ekman边界层,给出了潮流Ekman方程的解析解[式（32）－（35）],提出了对数边界层中潮流运动的方程组（式4－8）及其约束条件（式48）,并给出了潮流Ekman层与潮流对数边界层的匹配条件（式43）,还给出了计算浅海潮流垂直分布的解析表达式（36）－（39）。  相似文献   

Spatial Distributions of Phyllosoma Larvae (Crustacea: Decapoda: Palinuridae and Scyllaridae) in Taiwanese Waters     

Nariaki Inoue  Hideo Sekiguchi  Shinn-Pyng Yeh 《Journal of Oceanography》2001,57(5):535-548

Distributions and taxonomy of phyllosoma larvae were examined in Taiwanese waters, based on ichthyoplankton samples collected from May 1990 to July 1995. Phyllosoma larvae belonged to the two families Scyllaridae and Palinuridae representing 6 genera and 13 species. Of the collected phyllosoma larvae, those of Scyllarus and Panulirus species were most abundant, forming 90% of total numbers. Early stage Scyllarus and Panulirus phyllosoma larvae were abundant in Taiwanese waters. Middle to late stages (except the final stage) of Panulirus phyllosoma larvae were absent from the waters throughout the year, while those of Scyllarus phyllosoma larvae were collected in the waters. This suggests that all stages of Scyllarus phyllosoma larvae may be retained in the northern part of the waters around northern Taiwan while middle to late stages of Panulirus phyllosoma larvae may be flushed out from the waters, the sub-final and final stages then possibly returning to the waters. An anticlockwise eddy existed in the waters off northeastern Taiwan, which may be closely related to flushing out and returning of Panulirus phyllosoma larvae through a much longer planktonic period. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

我国东北地区夏季暴雨的气候学特征   总被引：5，自引：0，他引：5  

孙力  隋波  王晓明  刘实 《气候与环境研究》2010,15(6):778-786

利用东北三省和内蒙古东部200个测站1961～2005年的逐日降水资料,分析了东北地区夏季暴雨的空间分布特征和时间演变规律,以及各类暴雨与各种影响天气系统之间的气候统计关系。结果表明,在空间分布上,暴雨由东北地区的东南部向西北部递减的地域特征十分明显,绝大多数大范围和区域性暴雨一般都集中出现在东北地区的南部和中部,而局地暴雨的分布范围相对较广,地域差别也较小。在时间分布上,几十年来东北地区暴雨的阶段性变化特征十分明显,多暴雨和少暴雨的出现具有11～12年左右的低频变化周期。20世纪80年代初以来,暴雨日出现的年际变率有明显增加的趋势,特别是20世纪90年代中期以后,东北地区暴雨发生的次数虽然明显减少,但平均每个暴雨日的暴雨量却有所增加。在东北地区出现的局地暴雨中,以北方天气系统的影响贡献最大,而在区域性暴雨和大范围暴雨中,南方天气系统影响的比例明显增加。  相似文献   

Testing alarm-based earthquake predictions   总被引：1，自引：0，他引：1  

J. Douglas Zechar  Thomas H. Jordan 《Geophysical Journal International》2008,172(2):715-724

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Non-linear Bayesian joint inversion of seismic reflection coefficients   总被引：2，自引：0，他引：2  

Tor Erik Rabben  Håkon Tjelmeland  Bjørn Ursin 《Geophysical Journal International》2008,173(1):265-280

Inversion of seismic reflection coefficients is formulated in a Bayesian framework. Measured reflection coefficients and model parameters are assigned statistical distributions based on information known prior to the inversion, and together with the forward model uncertainties are propagated into the final result. This enables a quantification of the reliability of the inversion. Quadratic approximations to the Zoeppritz equations are used as the forward model. Compared with the linear approximations the bias is reduced and the uncertainty estimate is more reliable. The differences when using the quadratic approximations and the exact expressions are minor. The solution algorithm is sampling based, and because of the non-linear forward model, the Metropolis–Hastings algorithm is used. To achieve convergence it is important to keep strict control of the acceptance probability in the algorithm. Joint inversion using information from both reflected PP waves and converted PS waves yields smaller bias and reduced uncertainty compared to using only reflected PP waves.  相似文献   

Magnitude distribution of linear morphogenic earthquakes in the Mediterranean region: insights from palaeoseismological and historical data     

R. Caputo  M. Mucciarelli  S. Pavlides 《Geophysical Journal International》2008,174(3):930-940

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A Fractal Interaction Model for Winding Paths through Complex Distributions: Application to Soil Drainage Networks     

Miguel Ángel Martín  Miguel Reyes 《Pure and Applied Geophysics》2008,165(6):1153-1165

Water interacts with soil through pore channels putting mineral constituents and pollutants into solution. The irregularity of pore boundaries and the heterogeneity of distribution of soil minerals and contaminants are, among others, two factors influencing that interaction and, consequently, the leaching of chemicals and the dispersion of solute throughout the soil. This paper deals with the interaction of irregular winding dragging paths through soil complex distributions. A mathematical modelling of the interplay between multifractal distributions of mineral/pollutants in soil and fractal pore networks is presented. A Hölder path is used as a model of soil pore network and a multifractal measure as a model of soil complex distribution, obtaining a mathematical result which shows that the Hölder exponent of the path and the entropy dimension of the distribution may be used to quantify such interplay. Practical interpretation and potential applications of the above result in the context of soil are discussed. Since estimates of the value of both parameters can be obtained from field and laboratory data, hopefully this mathematical modelling might prove useful in the study of solute dispersion processes in soil.  相似文献