Activity of Wind-Blown Sand and the Formation of Feathered Sand Ridges in the Kumtagh Desert,China

We study the activity of wind-blown sand and its effects on the evolution of feathered sand ridges in the Kumtagh Desert, China, and attempt to reveal the formation process of feathered sand ridges using wind-tunnel experiments, remote sensing data, and detailed field observations from 2005 to 2008. The prevailing wind direction in the Kumtagh Desert is easterly in winter and north-easterly in other seasons. The average annual wind speed is 5.9 ms⁻¹, and winds sufficiently strong to entrain sand occur on 143 days per annum. The sand transport rate within 0.4 m of the ground is strongly influenced by local landforms, and is related to wind speed by a power function. Wind erosion occurs on the crest, the windward slope of crescent sand ridges and inter-ridge sand strips, where the blowing sand cloud is in an unsaturated state; in contrast, sand accumulation occurs on the leeward slope of the crescent sand ridges, where the blowing sand cloud is in an over-saturated state. These results indicate that the development of feathered sand ridges in the Kumtagh Desert is mainly controlled by the local wind regime. The dominant winds (from the north, north-north-east and north-east) and additional winds (from the east-north-east, east and east-south-east) determine the development of crescent sand ridges, but winds that are approximately parallel to sand ridges form the secondary inter-ridge sand strips.     

我国飞机观测气象资料概况及质量分析

为全面了解我国飞机观测气象资料的时空分布特征和质量状况,该文介绍了AMDAR(Aircraft MeteorologicalData Relay)计划的发展及我国通过AMDAR计划实施获取的飞机观测气象资料(又称AMDAR资料)的时空分布特征,分析了起飞和降落阶段飞机观测所获廓线资料的可用性,并分别对全球AMDAR资料和我国AMDAR资料进行极值检查、空间位置检验和时间一致性检验,对我国AMDAR资料错误率的月值变化和垂直分布特征进行了分析。结果表明:我国三分之二的AMDAR资料集中在飞机的起飞和降落阶段,并主要集中在我国中东部地区;利用我国AMDAR资料制作的廓线垂直分辨率大部分高于10 hPa。我国AMDAR资料的气温错误率低于全球水平,但风速错误率高于全球水平,错误资料主要集中在近地面层。从2008年开始,我国AMDAR资料的质量状况较往年有了明显改善,风速错误率一直维持在1.3%以下,气温错误率维持在0.2%以下。总体来说,我国AMDAR资料已成为我国高空气象观测资料的重要组成部分,资料质量稳定,具有较高的应用价值。     

Rainfall infiltration: infinite slope model for landslides triggering by rainstorm

Shallow slope failure due to heavy rainfall during rainstorm and typhoon is common in mountain areas. Among the models used for analyzing the slope stability, the rainwater infiltration model integrated with slope stability model can be an effective way to evaluate the stability of slopes during rainstorm. This paper will propose an integrated Green–Ampt infiltration model and infinite slope stability model for the analysis of shallow type slope failure. To verify the suitability of the proposed model, seven landslide cases occurred in Italy and Hong Kong are adopted in this paper. The results indicate that the proposed model can be used to distinguish failed and not-yet failed slopes. In addition, the proposed model can be used as the first approximation for estimating the occurrence time of a rainfall-induced shallow landslide and its depth of sliding.     

断层系的分维及储层裂缝发育带的预测技术

在勘探和开发碳酸盐岩气藏中，如何寻找和划定断裂及缝洞发育带是一重要研究课题。不同强度、不同受力方式的褶皱，它们的断裂及裂缝发育带的分布不同。要加深对复杂的地质构造，特别是控制油气聚集的断层、裂缝带的认识，仅靠现有地震勘探技术是很难实现的，用分形分维原理预测储层裂缝发育带可望有所突破。     

A new grid-cell-based method for error evaluation of vector-to-raster conversion

Error evaluation of rasterization of vector data is one of the most important research topics in the field of geographical information systems. Current methods for evaluating rasterization errors are far from perfect and need further improvement. The objective of this study is to introduce a new error evaluation method that is based on grid cells (EEM-BGC). The EEM-BGC follows four steps. First, the area of each land category inside a square is represented in a vector format. The size and location of the square are exactly the same as those of a grid cell that is to be generated by rasterization. Second, the area is treated as the attribute of the grid cell. Vector data are rasterized into n grids, where n is the number of land categories. Then, the relative area error resulting from rasterization for each land category in the grid cell is calculated in raster format. Lastly, the average of the relative area error for all land categories in the grid cell is computed with the area of a land category as weight. As a case study, the EEM-BGC is applied for evaluating the rasterization error of the land cover data of Beijing at a scale of 1 to 250,000. It is found that the error derived from a conventional method (denoted as y) is significantly underestimated in comparison with that derived from the new method (denoted as x), with y = 0.0014x ^2.6667. The EEM-BGC is effective in capturing not only the spatial distribution of rasterization errors at the grid-cell level but also the numerical distribution range of the errors. The EEM-BGC is more objective and accurate than any conventional method that is used for evaluating rasterization errors.     

程序在提高地震速报速度中的作用

本文重点介绍由福建省数字遥测地震台网自编的地震速报操作平台软件中的七个子程序及其主程序对提高地震速报速度的作用 ,同时也详细阐述实现该软件的几项关键性技术。     

A CADASTRAL SPATIAL DATA STORAGE STRUCTURE BASED ON RELATIONAL DATABASE

1　ＩｎｔｒｏｄｕｃｔｉｏｎＣａｄａｓｔｒａｌｍａｐｓａｎｄｃａｄａｓｔｒａｌａｔｔｒｉｂｕｔｅｓａｒｅｔｈｅｃｏｒｅｃｏｎｔｅｎｔｓｏｆｃａｄａｓｔｒａｌｉｎｆｏｒｍａｔｉｏｎｍａｎａｇｅ ｍｅｎｔ .ＳｏｍｅｏｆｔｈｅｄｅｖｅｌｏｐｅｄｃａｄａｓｔｒａｌｍａｎａｇｅｍｅｎｔｓｙｓｔｅｍｓｅｍｐｌｏｙＧＩＳｓｏｆｔｗａｒｅ (ｉ.ｅ .Ｍａｐｉｎｆｏ ,Ａｒ ｃｖｉｅｗｏｒＭａｐｔｉｔｕｄｅｅｔｃ .)ｔｏｍａｎａｇｅｃａｄａｓｔｒａｌｍａｐｓａｎｄｕｓｅｒｅｌａｔｉｏｎａｌｄａｔａｂａｓｅ (ｅ .ｇ .ＳＱＬ…     

吉林中部志留─泥盆纪生物地层、群落生态及生物古地理

吉林省中部的二道沟组、小绥河组、张家屯组的时代归属，一直是国内、外地质学家争议的问题之一。根据无脊椎动物化石鉴定结果，张家屯组的时代为志留纪Ｌｕｄｌｏｗ晚期至Ｐｒｉｄｏｌｉ早期，小绥河组为志留纪末Ｐｒｉｄｏｌｉ期或泥盆纪初Ｌｏｃｈｋｏｖ期，二道沟组为早泥盆世Ｌｏｃｈｋｏｖ早期。根据上述地层中珊瑚和腕足动物化石，推测它们当时是生活在正常浅海的生活环境中，大致相当于底栖组合ＢＡ３。我国东北地区中古生代存在着两个不同的动物地理区：华北地台北缘产Ｒｅｔｚｉｅｌｌａ腕足动物群和Ｃａｒｌｉｎａｓｔｒａｅａ珊瑚动物群，吉林中部就位于这一个动物地理区范围之内；西伯利亚地台南缘产Ｔｕｖａｅｌｌａ腕足动物群。