云南省Internet网络天气预报会商系统

云南省基于Internet网络的天气预报会商系统覆盖云南省、地 (州 )、县三级。系统采用了Internet网络技术、数据库技术 ,实现了省、地 (州 )、县天气预报发布及浏览查询、预报讨论BBS、天气预报会商室、系统管理 ,在线短消息互发等功能。     

An internal-external optimized convolutional neural network for arbitrary orientated object detection from optical remote sensing images

Due to the bird's eye view of remote sensing sensors, the orientational information of an object is a key factor that has to be considered in object detection. ...     

Recognition of Significant Surface Soil Geochemical Anomalies Via Weighted 3D Shortest-Distance Field of Subsurface Orebodies: A Case Study in the Hongtoushan Copper Mine,NE China

Natural Resources Research - Quantitative prediction of concealed mineralization is always confronted with difficulties in comprehensive analysis between 2D and 3D data and between qualitative and...     

关于辽宁地区b值方法定量预测的研究

本文利用地震学分析预报方法程式指南和“八五”攻关成果中提出的地震b值定量预测方法,对辽宁及邻区1969年以来发生的8次地震震例作了回顾性检验研究。在此基础上,根据震前b值的变化特征,总结出了可能适用于辽宁地区半年左右尺度的b值预测方法的异常羊别指标及预报规则。     

中国及邻区现代构造应力场的数值模拟

我国及邻区的现代构造应力场作为一平面应力问题用有限单元法进行了计算。将本区地壳看成是一不均匀的弹性板,根据各地区杨氏模量E、泊松比v和地壳厚度T的不同,组成12种材料区。全区被分成288个三角形单元。考虑了五种应力和位移边界条件,这些边界条件分别反映了印度洋板块、太平洋板块及菲律宾海板块对我国及邻区施加应力的相对大小。将计算得到的最大剪应力值与强震分布进行对比,将最大主压应力方向与震源机制解的最大主压应力方向进行对比,选择一种和实际符合得最好的边界条件作为可取的模式。结果表明:来自印度洋板块的作用力最大,大约是来自太平洋板块和菲律宾海板块作用力的两倍。     

频率域全波形反演方法研究进展

全波形反演是一种利用地震波传播的动力学特征来获取地下介质物性参数的反演方法,可为揭示地下精细结构提供重要依据。本文以弹性波方程作为数学模型来模拟地震波传播规律并进行相应的反演方法研究。为提高计算效率与反演结果的准确性,可将近似解析离散化（NAD）算子用于频率域弹性波方程的正演模拟。本文在频率域NAD离散的基础上推导阻抗矩阵的稀疏分块结构与反演目标函数对模型参数的梯度计算公式,由此建立基于NAD算子的频率域弹性波全波形反演方法。为验证该方法的有效性,文中通过数值实验对多种典型介质模型进行反演计算,均得到了理想的反演结果。

     

Application of saddlepoint approximation in reliability analysis of dynamic systems

The application of the saddlepoint approximation to reliability analysis of dynamic systems is investigated. The failure event in reliability problems is formulated as the exceedance of a single performance variable over a prescribed threshold level. The saddlepoint approximation technique provides a choice to estimate the cumulative distribution function (CDF) of the performance variable. The failure probability is obtained as the value of the complement CDF at a specif ied threshold. The method requires computing the saddlepoint from a simple algebraic equation that depends on the cumulant generating function (CGF) of the performance variable. A method for calculating the saddlepoint using random samples of the performance variable is presented. The applicable region of the saddlepoint approximation is discussed in detail. A 10-story shear building model with white noise excitation illustrates the accuracy and effi ciency of the proposed methodology.     

Microbial community dynamics and biodegradation of polycyclic aromatic hydrocarbons in polluted marine sediments in Hong Kong

Dynamics of microbial community and biodegradation of polycyclic aromatic hydrocarbons (PAHs) in polluted marine sediments, artificially spiked with a mixture of PAHs (fluorene, phenanthrene, fluoranthene and pyrene), were examined for a period of 60 days. Microbial communities were characterised by bacterial counts, ester-linked fatty acid methyl ester (EL-FAME) analysis and denaturing gradient gel electrophoresis (DGGE). A noted reduction in species diversity occurred only in the high PAH level treatment at onset. Both EL-FAME and DGGE demonstrated a marked shift in microbial community, in all the PAH level treatments, afterwards, with increases in the number of fatty acid degraders, the relative abundance of fatty acid biomarkers for gram-negative bacteria and a decrease in species diversity. The shift was also accompanied by the significant decrease in PAH concentrations. By the end of the experiment, diversity indices, based on both approaches, recovered when PAH concentrations declined to their background levels, except in the high PAH level treatment.     

Study on uncertainty of inversion and resolution limit in the presence of noise

This study analyzed the uncertainty of inversion and the resolution limit in the presence of noise by means of statistical experiments. The exhaustive method is adopted to obtain the global optimal solution in each experiment. We found that even with small level of noise, solutions fluctuate in a large range for the thin bed. The distribution of solutions in the presence of noise is closely related to the spread of the cost function in the absence of noise. As a result, the area of a certain neighborhood around the true solution on the spread of the cost function in the absence of noise is used to evaluate the uncertainty of inversion and the resolution limit in the presence of noise. In the case that the SNR (signal-to-noise ratio) is 5 in this study, solutions focus around the true solution with a very small uncertainty only when the bed thickness is greater than the reciprocal of the double predominant frequency of the convoluting wavelet.     

地层证据--对大别造山带汇聚历史的制约

大别造山带的汇聚演化历史一直存在不同的认识,来自扬子陆块和华北陆块显生宙以来的地层记录以及北淮阳地区的地层记录可能为两个陆块的汇聚模式提供制约。通过对扬子陆块与华北陆块显生宙以来岩相古地理进行比较,其中3个阶段相似, 2个阶段差别很大。以浊积岩发育作为俯冲阶段的标志,磨拉石建造出现作为闭合的标志,显生宙以来,大别造山带曾经历了两次俯冲和两次汇聚,俯冲时间分别是晚奥陶世—早志留世和早三叠世,汇聚的时间分别为中 晚泥盆世和中三叠世,早期的汇聚具有软碰撞特征,以上认知得到了北淮阳地区地层、古生物和沉积记录的支持,同时也与大别山造山带榴辉岩的同位素年龄数据基本吻合。高压 超高压变质岩在晚三叠世处于快速折返阶段,早侏罗世以前到达地表,其平均折返隆升速率为39～66mm/a。