基于GIS的气象干旱评估系统研究——以山东省潍坊市为例   总被引：1，自引：0，他引：1  

王潇宇  沙莎  何永健 《气象与减灾研究》2010,33(4):43-47

利用山东省潍坊市1971-2009年气象观测资料,以及各县市、乡镇街道的历史灾情记录和社会经济数据,选择适合研究区域的干旱判别指标,建立了干旱灾害评估模型。以Arc GIS9.3为开发平台,SQL Server 2005为干旱评估的信息数据库,并利用Delphi7.0等软件工具开发了基于GIS的潍坊市气象干旱评估系统,对研究区域进行干旱灾害预警和灾害损失评估。  相似文献   

基于多状态Markov链模式的极端降水模拟试验   总被引：3，自引：2，他引：1  

丁裕国  张金铃  江志红 《气象学报》2009,67(1):20-27

文中建立了基于多状态一阶Markov链的逐日降水量随机模式式结合广义帕雷托分布(GPD)产生夏季逐日极端降水量的模拟资料,结果所显示的各种气候特征表明,绝大多数站点(尤其是中国东部多雨地区)都达到较高的精度.分析表明,该模式对中国东部极端降水特征的模拟能力在某些方面优于两状态一阶Markov链模式.对东部6个代表站模拟试验结果表明,月降水均方差、日降水极大值、月半均降水日数、日降水均方差、日平均降水量等指标与实况比较,均证明该模式对逐日降水量的模拟效果较好,基本模拟出降水量的各种特征.对中同东部78个代表站采用的两种模式模拟结果对比发现,除日平均降水量以外,月半均降水日数、日降水平均极大值都与实际观测结果较为一致,总体上优于两状态模式,说明用该模式在全国范围内模拟逐日降水特征尤其是极端降水特征有较高的町行性.例如,由其中6个代表站模拟资料所拟合的极端降水GPD模式具有较高的拟合优度.无论从门限值或重现期值来看都可发现模拟与实测结果有较好的相似性,且两者门限值的误差越小,重现期极值的差距也越小.证明Markov链模式对极端降水的模拟有广泛的适用性.  相似文献   

Theory for Reconstruction of an Unknown Number of Contaminant Sources using Probabilistic Inference   总被引：1，自引：0，他引：1  

Eugene Yee 《Boundary-Layer Meteorology》2008,127(3):359-394

We address the inverse problem of source reconstruction for the difficult case of multiple sources when the number of sources is unknown a priori. The problem is solved using a Bayesian probabilistic inferential framework in which Bayesian probability theory is used to derive the posterior probability density function for the number of sources and for the parameters (e.g., location, emission rate, release time and duration) that characterize each source. A mapping (source–receptor relationship) that relates a multiple source distribution to the concentration measurements made by an array of detectors is formulated based on a forward-time Lagrangian stochastic model. A computationally efficient methodology for determination of the likelihood function for the problem, based on an adjoint representation of the source–receptor relationship and realized in terms of a backward-time Lagrangian stochastic model, is described. An efficient computational algorithm based on a parallel tempered Metropolis-coupled reversible-jump Markov chain Monte Carlo (MCMC) method is formulated and implemented to draw samples from the posterior probability density function of the source parameters. This methodology allows the MCMC method to initiate jumps between the hypothesis spaces corresponding to different numbers of sources in the source distribution and, thereby, allows a sample from the full joint posterior distribution of the number of sources and the parameters for each source to be obtained. The proposed methodology for source reconstruction is tested using synthetic concentration data generated for cases involving two and three unknown sources.  相似文献   

一种快速3维建模方法在地质模拟中的应用     

史云飞  张玲玲  王峰  成遣 《测绘与空间地理信息》2005,28(3):81-84

论述了一种快速建模方法在地质模拟中的应用。这种建模方法采用了改进的三角形生长法生成TIN来表达地形及各地层界面;采用离散钻孔点双向链表、三角形双向链表以及垂直连体来快速生成三棱柱从而构建地层体素。  相似文献   

Tests for quasi-independence of embedded markov chains     

Jinsheng Yu 《Mathematical Geology》1984,16(3):267-282

This paper introduces the concept of quasi-independence into embedded Markov chains and identifies the maximum likelihood frequency estimates to be used with ² tests of the null hypothesis of quasi-independence within an embedded Markov chain.  相似文献   

求解矩阵链乘序的最优划分树算法     

张钟澍  李青  邓碧敏  关忠仁 《成都信息工程学院学报》1994,(1)

作者提出了关于矩阵链乘最优三角划分的一些定理和最优划分树的概念，并根据这些理论，得出一种时间花费为Ｏ（ｎｌｏｇｎ）的矩阵链乘最优次序求解算法。  相似文献   

震灾保险新制式的理论依据及其科学内涵     

巫孟还  阮圣娜 《华南地震》1997,17(1):88-93

震灾保险新制式是建立在新观念，新思维，新概仿之上的一种独特的保险机制，本文通过对其理论基础以及科学－社会意义的阐述，进一步揭示了这一新型制式的实质和内涵。  相似文献   

Global sounding of sporadic E layers by the GPS/MET radio occultation experiment   总被引：1，自引：0，他引：1  

initK. K. Hocke  K. Igarashi  M. Nakamura  P. Wilkinson  J. Wu  A. Pavelyev  J. Wickert   《Journal of Atmospheric and Solar》2001,63(18):1973

The GPS radio occultation technique is sensitive for layered structures with horizontal scales of around 100 km and with vertical scales of a few 100 m or more at the Earth's limb. These structures cause strong fluctuations of the GPS L1 and L2 phase paths which have been measured by a GPS receiver onboard of Microlab-1 satellite in 730 km orbit during the GPS/Meteorology experiment (GPS/MET of UCAR, Boulder). By means of GPS/MET radio occultation data, profiles of electron density fluctuations are derived for the mesosphere/lower thermosphere region with a height resolution of around 1 km. Data analysis of 1900 radio occultation events in June/July 1995, 1540 events in October 1995, and 2690 events in February 1997 confirms seasonal dependence of sporadic E layers. The meridian slices of average sporadic E activity show a dominance of plasma irregularities in the summer hemisphere. The irregularities mainly occur at heights 90–110 km. Auroral and equatorial sporadic E, electron density depletions, and multiple ionization layers are also present in the high resolution GPS/MET data. The multiple layers often have a distance of around 5–10 km in height, and appear up to a height of 140 km (upper height limit for 50 Hz sampling rate of GPS receiver). For February and June, the GPS/MET observations are compared to ground-based observations of the Asia/Australia ionosonde chain.  相似文献   

水热成矿流体中的短链羧酸   总被引：1，自引：1，他引：1  

曾贻善 《地学前缘》2001,8(4):397-401

文中简述了天然水流体中的短链羧酸产出状况。短链羧酸地球化学的研究目前集中于沉积盆地和表生环境。根据C H O体系中某些C H O化合物的化学关系和热力学分析 ,推测深部水热流体中有可能存在短链羧酸。研究高温热液矿床矿物流体包裹体的水溶有机组分可能是检验这一推测的突破口。某些石英脉型热液矿床的矿物流体包裹体压碎浸取和离子色谱分析确定 ,成矿流体中存在少量短链羧酸 ,而且甲酸是优势物种。文章讨论了矿物包裹体浸取实验结果需要进一步探讨的问题 ,认为研究水热成矿流体短链羧酸地球化学具有重要的理论意义。  相似文献   

广州海印花园深基坑支护工程施工技术     

刘联伟  丁松年 《中国煤田地质》2001,13(1):53-55

对位于珠江边，周边施工环境恶劣，地质条件差的广州海印花园深基坑支护工程施工技术进行了总结，为今后类似的复杂大型深基坑支护工程施工提供了成功的经验。  相似文献