Estimation of Hourly and Daily Global Solar Radiation at Clear Days Using an Approach Based on Modified Version of Gaussian Distribution     

S. M. El shazly 《大气科学进展》1996,13(3):349-358

The performance of two models,Jam and Baig,based on the modified version of Gaussian distribution function in estimating the daily total of global solar radiation and its distribution through the hours of the day from sunrise to sunset al any clear day is evaluated with our own measured data in the period from June 1992 to May 1993 in Qena Egypt The results show a high relative deviation of calculated values from measured ones,especially for Jain model,in the most hours of the day,except for those near to local noon.This misfit behavior is quite obvious in the early morning and late afternoon A new approach has been proposed in this paper to estimate the daily and hourly global solar radiation This model performs with very high accuracy on the recorded data in our region.The validity of this approach was verified with new measurements in some clear days in June and August 1994.The resultant very low relative deviation of the calculated values of global solar radiation from the measured ones confirms the  相似文献   

上行离子密度分布特性的理论研究          下载免费PDF全文

史建魁  刘振兴 《地球物理学报》1996,39(2):159-168

采用动力学方程，求解了定态情况下磁层中上行离子沿磁力线的分布函数，针对不同的Ｋ_ｐ指数，分别对北半球极光带区起源的上行离子Ｏ_＋、Ｈ_＋和Ｈｅ_＋在子午面内沿磁力线的密度分布及其特性进行了研究．结果表明：１．沿磁力线向外，上行离子密度在近地空间呈急剧下降趋势，在远地空间呈缓慢下降趋势；２．重离子或初始能量较小的离子，其密度沿磁力线向外下降较快；３．Ｋ_ｐ指数越大，离子进入磁层的空间范围越大；４．离子的投掷角分布对密度分布的影响甚小；５．离子密度沿磁力线的下降程度随到Ｘ轴距离的增大而呈增大趋势；６．在典型参数条件下，求得上行离子Ｏ_＋在等离子体片边界附近的密度为１０^－３－１０^－２个ｃｍ^－３，这与观测结果相一致．  相似文献   

潜在震源区内部空间非均匀分布地震区划方法在攀西地区和晋中南地区的应用   总被引：2，自引：1，他引：2  

高孟潭  胥广银 《中国地震》1996,(Z1)

本文依据潜在震源区内部地震非均匀分布模型研究了攀西地区和晋中南地区地震区划问题。研究结果表明，一般使用的均匀分布模型会低估地震危险性结果，导致高烈度分区的面积缩小。本文讨论了不同的确定非均匀分布概率的方法对地震区划结果的影响。  相似文献   

Faulting in zones of lithospheric extension: Quantitative analysis of natural and experimental data   总被引：1，自引：0，他引：1  

S. I. Sherman 《Pure and Applied Geophysics》1996,146(3-4):421-446

Quantitative relationships between major fault parameters from geological observations and laboratory experiments are compared. Relationships are established between fault length, number, depth of fault penetration, amplitude of displacement and other characteristics. The width of destruction zones is estimated. Spacing between parallel faults of compatible length is evaluated. It is shown that there is a stable correlation between fault length and number, which is independent from the mode of loading the material under destruction. Destruction of the lithosphere is believed to occur according to the laws of deformation of Maxwell elasto-viscous body.  相似文献   

Estimation of quantiles and confidence intervals for the log-Gumbel distribution     

J. -H. Heo  J. D. Salas 《Stochastic Environmental Research and Risk Assessment (SERRA)》1996,10(3):187-207

The log-Gumbel distribution is one of the extreme value distributions which has been widely used in flood frequency analysis. This distribution has been examined in this paper regarding quantile estimation and confidence intervals of quantiles. Specific estimation algorithms based on the methods of moments (MOM), probability weighted moments (PWM) and maximum likelihood (ML) are presented. The applicability of the estimation procedures and comparison among the methods have been illustrated based on an application example considering the flood data of the St. Mary's River.  相似文献   

An effective approach to determine the dynamic source parameters     

Xiaofei Chen  Keiiti Aki 《Pure and Applied Geophysics》1996,146(3-4):689-696

In this study, we present a new and effective method to determine the dynamic source parameters (i.e., stress drop and strength distribution). We first assume that the kinematic source parameters, i.e., the slip and rupture time distributions on the fault plane, are known from the previous source inversion studies. Then, using the seismic source representation theorem we determine the dynamic stress field on a fault plane from known kinematic parameters. Finally, we determine the strength of the fault defined as the peak stress just before the rupture. We have tested the validity of this method by using an illustrative two-dimensional analytical example. To assess the applicability of this method, we have applied it to study the 1979 Imperial Valley earthquake, and obtained consistent results with those ofMiyatake's (1992) andQuin's (1990). Compared with previous methods, this new method is simple, straightforward and accurate, and needs much less calculation. Therefore, it is expected to be useful in exploring the seismic source process.  相似文献   

华北地区地震时间结构的多分形特征   总被引：2，自引：0，他引：2  

刁守中  蒋海昆 《内陆地震》1996,10(2):103-112

利用固定半径法和直接计算法系统研究了华北地区（Ｎ３０°～４３°，λＥ１０６°～１２５°）１３个Ｋ表性子区地震时间结构的广义维数Ｄｑ—ｑ及标度指数谱ｆ（ａ）—ａ的特征，并与单—Ｄｑ—ｔ曲线进行了对比。结果表明；（１）华北地区地震时间结构为多分形结构，单一分形不能完整地描述其分形特征，应该用Ｄｑ—ｑ或ｆ（ａ）—ａ来加以分析；（２）华北强震前的０．５～２．０年．周围地区地震活动的时间多分形结构出现异常，主要表现为ｑ为负时Ｄｑ增大、ｑ为正时Ｄｑ减小，或ｆ（ａ）两端点下降，ａ跨度增大及顶点右偏等现象，这是对地震密集—平静现象的另一种描述；（３）华北地区地震时间多分形方法回顾性预报评分Ｒ＝０．４７，说明其有一定预报效能，是有前景的预报方法。  相似文献   

Cyclic strength and deformation of crushable carbonate sand     

Masayuki Hyodo  Noritaka Aramaki  Masayuki Itoh  Adrian F.L. Hyde 《Soil Dynamics and Earthquake Engineering》1996,15(5):331-336

Cyclic triaxial tests have been carried out on a skeletal carbonate sand from the west coast of Eire. Results are presented for undrained cyclic shear tests on samples with 80% of relative density consolidated under both isotropic and anisotropic conditions. Failure was defined as a 5% double amplitude cyclic strain and a 5% peak axial strain for stress-reversal and non-reversal stress conditions, respectively. Using this definition the cyclic strength for isotropically consolidated samples was affected by the confining pressure although the angular platey nature of the sand resulted in higher cyclic strengths than for a comparable silica sand. For anisotropically consolidated samples the cyclic strength increased with increasing initial static shear stress while on the other hand the cyclic strength normalised in the usual way with respect to the initial confining pressure decreased as this pressure increased.  相似文献   

中国地表感热的气候计算及其分布          下载免费PDF全文

高庆先  翁笃鸣 《大气科学学报》1996,19(2):238-244

讨论了我国地表感热的气候计算问题,提出以鲍文比法为基础的感热气候计算式,并据此计算出全国215站月、年平均感热通量密度,进而分析了其在全国的时空分布特点。  相似文献   

龙门山断裂带测区古构造残余应力随深度分布及带中残余能量   总被引：1，自引：0，他引：1       下载免费PDF全文

安欧  高国宝 《地震地质》1996,18(1):25-29

以岩体正交异性弹性理论为基础，用Ｘ射线法，在龙门山断裂带测区，选取３个小区深钻孔系列的岩心，测量了岩体中宏观残余应力场的水平和铅直三维主分量、水平和铅直最大剪应力，及其应变能密度随深度的分布，分析了它们沿深度的分布规律，估算了该断裂带岩体中储存的宏观残余弹性应变能的量级  相似文献