胶东地区地质体含金性的地质地球化学评价   总被引：2，自引：0，他引：2       下载免费PDF全文

丁式江  翟裕生  邓军 《地质找矿论丛》1997,12(3):1-10

通过分析胶东地区各地质体例 的金根率分布模型,金含量的分数维特征,金及相关元素的组合特征天南地北来评价胶来地区各地质体的含金性。结果表明：胶东群,粉子山群,玲珑型花岗岩为金的矿源岩,郭家岭型花岗岩可能即为本区的金成矿提供成矿物质又起到了“热机”的作用。  相似文献   

河南一次局地强降水过程的中尺度分析     

张启绍  芦阿咪  张一平 《气象与环境科学》2016,39(1):74-81

利用NCEP/NCAR再分析资料、常规观测资料,采用常规中尺度分析方法和Barnes滤波方法,对2013年6月7日14-20时林州站出现的一次局地强降水过程进行分析,结果发现此次降水过程是发生在东高西低的环流形势下,降水主要发生在500 h Pa低槽槽前;江淮气旋北端不断增强的偏东气流为降水区提供了充足的水汽条件;地形抬升有利于触发对流,并对降水有增幅作用。通过滤波分析发现,此次过程林州处于鞍型场中,且处于风向辐合线和风速辐合线附近;局地强降水发生在水汽通量负散度绝对值大值区与负散度绝对值大值中心重叠区。经过滤波前后对比发现,此次过程分析原始场得出的辐合上升运动区、水汽辐合中心、层结不稳定区与局地强降水落区有一定的偏差,而滤波场特征比较有指示意义。负散度绝对值大值区和地面中尺度辐合线附近有利于回波生成和发展;两回波带合并容易加强;短历时强降水发生前,垂直累积液态水含量迅速跃增;雷达径向速度辐合区有利于回波发展加强。  相似文献   

Separation of a geochemical anomaly from background by fractal and U-statistic methods,a case study: Khooni district,Central Iran     

《Chemie der Erde / Geochemistry》2016,76(4):491-499

Separation of geochemical anomalies from background are one of the important steps in mineral exploration. The Khooni mineral district (Central Iran) has complex geochemical surface expression due to a complex geological background. This region was chosen as a study area for recognition of the spatial distribution of geochemical elements and separating anomalies from background using stream sediment geochemical data. In the past decades, geochemical anomalies have been identified by means of various methods. Some of these separation methods include: statistical analysis methods, spatial statistical methods and fractal and multi-fractal methods. In this article, two efficient methods, i.e. U-statistics and the fractal concentration-area for separation and detection of anomalous areas of the background were used. The U spatial statistic method is a weighted mean, which considers sampling point positions and their spatial relation in the estimation of anomaly location. Also, fractal and multi-fractal models have also been applied to separate anomalies from background values. In this paper, the concentration–area model (C–A) was suggested to separate the anomaly of background. For this purpose, about 256 stream sediment samples were collected and analyzed. Then anomaly maps of elements were generated based on U spatial statistics and the C-A fractal methods for Au, As and Sb elements. According to obtained results, the U-statistics method performed better than C-A method. Because the comparisons of the known deposits and occurrences against the anomalous area created using thresholds from U-statistics and C-A method show that the spatial U-statistics method hits all of 3 known deposits and occurrences, the C-A fractal method hits 1 and fails 2. In addition, the results showed that these methods with regard to spatial distribution and variability within neighboring samples, in addition to concentration value frequency distributions and correlation coefficients, have more accurate results than the traditional approaches.  相似文献   

Mapping rice-fallow cropland areas for short-season grain legumes intensification in South Asia using MODIS 250 m time-series data     

Murali Krishna Gumma  Prasad S. Thenkabail  Pardharsadhi Teluguntla  Mahesh N. Rao  Irshad A. Mohammed  Anthony M. Whitbread 《International Journal of Digital Earth》2016,9(10):981-1003

The goal of this study was to map rainfed and irrigated rice-fallow cropland areas across South Asia, using MODIS 250?m time-series data and identify where the farming system may be intensified by the inclusion of a short-season crop during the fallow period. Rice-fallow cropland areas are those areas where rice is grown during the kharif growing season (June–October), followed by a fallow during the rabi season (November–February). These cropland areas are not suitable for growing rabi-season rice due to their high water needs, but are suitable for a short -season (≤3 months), low water-consuming grain legumes such as chickpea (Cicer arietinum L.), black gram, green gram, and lentils. Intensification (double-cropping) in this manner can improve smallholder farmer’s incomes and soil health via rich nitrogen-fixation legume crops as well as address food security challenges of ballooning populations without having to expand croplands. Several grain legumes, primarily chickpea, are increasingly grown across Asia as a source of income for smallholder farmers and at the same time providing rich and cheap source of protein that can improve the nutritional quality of diets in the region. The suitability of rainfed and irrigated rice-fallow croplands for grain legume cultivation across South Asia were defined by these identifiers: (a) rice crop is grown during the primary (kharif) crop growing season or during the north-west monsoon season (June–October); (b) same croplands are left fallow during the second (rabi) season or during the south-east monsoon season (November–February); and (c) ability to support low water-consuming, short-growing season (≤3 months) grain legumes (chickpea, black gram, green gram, and lentils) during rabi season. Existing irrigated or rainfed crops such as rice or wheat that were grown during kharif were not considered suitable for growing during the rabi season, because the moisture/water demand of these crops is too high. The study established cropland classes based on the every 16-day 250?m normalized difference vegetation index (NDVI) time series for one year (June 2010–May 2011) of Moderate Resolution Imaging Spectroradiometer (MODIS) data, using spectral matching techniques (SMTs), and extensive field knowledge. Map accuracy was evaluated based on independent ground survey data as well as compared with available sub-national level statistics. The producers’ and users’ accuracies of the cropland fallow classes were between 75% and 82%. The overall accuracy and the kappa coefficient estimated for rice classes were 82% and 0.79, respectively. The analysis estimated approximately 22.3?Mha of suitable rice-fallow areas in South Asia, with 88.3% in India, 0.5% in Pakistan, 1.1% in Sri Lanka, 8.7% in Bangladesh, 1.4% in Nepal, and 0.02% in Bhutan. Decision-makers can target these areas for sustainable intensification of short-duration grain legumes.  相似文献   

辅助模型辨识方法(3):输入非线性输出误差自回归系统     

丁锋  毛亚文 《南京气象学院学报》2016,8(3):193-214

输入非线性系统包括输入非线性方程误差类系统和输入非线性输出误差类系统.针对输入非线性输出误差自回归系统,分别基于过参数化模型,基于关键项分离原理,基于数据滤波技术,研究了相应的基于过参数化模型的辅助模型递推辨识方法、基于关键项分离的辅助模型递推辨识方法、基于数据滤波的辅助模型递推辨识方法.这些方法可以推广到其他输入非线性输出误差系统、输出非线性输出误差系统、反馈非线性系统等.并给出了几个典型辨识算法的计算步骤、流程图和计算量.  相似文献   

辅助模型辨识方法(1):自回归输出误差系统     

丁锋 《南京气象学院学报》2016,8(1):1-22

研究了自回归输出误差(AR-OE)系统的辅助模型随机梯度算法、辅助模型多新息随机梯度算法、辅助模型递推最小二乘算法,自回归输出误差自回归滑动平均(AR-OEARMA)系统(即AR-Box-Jenkins系统)的辅助模型广义增广随机梯度算法、辅助模型多新息广义增广随机梯度算法、辅助模型递推广义增广最小二乘算法,以及AR-Box-Jenkins系统的基于滤波的辅助模型广义增广随机梯度算法、基于滤波的辅助模型多新息广义增广随机梯度算法、基于滤波的辅助模型递推广义增广最小二乘算法等.  相似文献   

Application of change detection techniques in geomorphological evolution of coastal areas. Example: Mouth of the River Ebro (period 1957–2013)     

《Applied geography (Sevenoaks, England)》2016

This study aims to test the effectiveness of the changes detection techniques to determine the evolution of the various geomorphological units identified in Ebro River mouth, in order to establish their evolutionary trends and to explain the changes between 1957 and 2013 years. To evaluate the most significant changes in the Ebro River mouth, the different geomorphological units present in the area were obtained by interpretation of aerial imagery. It has been noted that the period 1957–1984 was more dynamic and intense than the period 1984–2013, indicating a loss of capacity of the processes causing changes, and the shoreline is evolving toward a more stable morphology. It was determined that the most important processes that took place were mainly marine erosion processes and anthropogenic expansion. On the characterization in the entire period studied, it was determined that growth or decrease processes (net change) are as relevant in the region as processes which include location changes (swap). The change analysis methodology allows analyzing the evolution of coastal geomorphology, since it allows the determination and characterization of the principal transitions amongst the identified geomorphological units, and, therefore, to obtain the main processes that dominate the area, which is particularly relevant on highly vulnerable environments, such as coastal deltaic areas.  相似文献   

沈阳都市圈的范围及城镇空间分布的分形研究   总被引：1，自引：1，他引：0  

闫广华 《地理科学》2016,36(11):1736-1742

科学界定都市圈范围是研究都市圈的基础,采用2014年沈阳市及周边市县镇乡社会经济统计数据,采用断裂点和经济隶属度模型,界定沈阳都市圈范围。用经济隶属度指标划分城镇体系。用分形理论分析沈阳都市圈城镇的空间分布特征,结果为：集聚维数、容量维数、信息维数和关系维数分别为1.430 1、1.294 1、1.473 5和0.393 8,说明沈阳都市圈城镇空间向心性集聚分布较为显著,城镇空间分布的均衡性较好,城镇空间分布具有较强的相关性,形成了以沈阳市为中心呈凝聚态分布的都市圈城镇空间结构,城镇间联系较为紧密,相互作用较强。进而提出沈阳都市圈城镇空间分布优化的对策。  相似文献   

雷达资料同化对2015年台风彩虹数值模拟改进          下载免费PDF全文

冯佳宁  端义宏  徐晶  张兴海  胡皓 《应用气象学报》2017,28(4):399-413

基于WRF中尺度模式,采用集合卡尔曼滤波方法同化中国岸基多普勒天气雷达径向速度资料,对2015年登陆台风彩虹（1522）进行数值试验。从台风强度、路径、结构等方面验证了同化效果,并对不同区域雷达观测资料的同化敏感性进行讨论。试验结果表明:在同化窗内同化分析场台风位置误差相比未同化平均减小15 km,最多时刻减小38 km,同化资料时次越多,确定性预报路径误差越小。同化雷达资料后较好地反映出台风彩虹（1522）近海加强过程,台风中心最低气压同化分析和预报误差相比未同化最大减小超过25 hPa,台风眼的尺度、眼墙处对流非对称结构相比未同化与观测更加接近。试验还表明:台风内核100 km范围内的雷达观测对同化效果影响最大,仅同化这部分资料（约占总量的20%）各方面效果与同化全部资料相近,而仅同化100 km以外资料效果明显不及同化所有资料。仅同化台风内核雷达观测资料可以在不影响同化效果的前提下,使集合同化计算机时减小为原来的1/3,该策略可为台风实际业务预报提供一定参考。  相似文献   

混合智能优化算法的SAR图像特征选择   总被引：1，自引：0，他引：1  

张琴  谷雨  徐英  赖晓平 《遥感学报》2016,20(1):73-79

为提高SAR图像自动目标识别的准确率及实时性,提出了一种基于混合智能优化的SAR图像特征选择算法。首先,采用分形特征对SAR图像进行增强,基于分割后的图像提出了一种基于图像矩的方位角估计方法。然后基于未校正和校正后的图像分别提取Zernike矩、Gabor小波系数和灰度共生矩阵构成候选特征集合,使用遗传算法结合二值粒子群的混合优化算法实现SAR图像特征选择。最后,采用MSTAR数据库验证本文算法的有效性。实验结果表明,优化后的特征集合具有一定泛化能力,一方面提高了SAR目标识别的准确率,另一方面减小了SAR图像目标识别的时间。  相似文献