Regional characteristics of dust events in China

The regional characteristics of dust events in China has been mainly studied by using the data of dust storm, wind-blown sand and floating dust from 338 observation stations through China from 1954 to 2000. The results of this study are as follows: (1) In China, there are two high frequent areas of dust events, one is located in the area of Minfeng and Hotan in the South Xinjiang Basin, the other is situated in the area of Minqin and Jilantai in the Hexi Region. Furthermore, the spatial distributions of the various types of dust events are different. The dust storms mainly occur in the arid and semiarid areas covering the deserts and the areas undergoing desertification in northern China. Wind-blown sand and floating-dust not only occur in the areas where dust storms occur, but also extend to the neighboring areas. The range of wind-blown sand extends northeastward and southeastward, but floating-dust mainly extends southeastward to the low-latitude region such as the East China Plain and the area of the middle and lower reaches of the Yangtze River. Compared with wind-blown sand, the floating-dust seldom occurs in the high latitude areas such as North Xinjiang and Northeast China. (2) The affected areas of dust storms can be divided into seven sub-regions, that is, North Xinjiang Region, South Xinjiang Region, Hexi Region, Qaidam Basin Region, Hetao Region, Northeastern China Region and Qinghai-Xizang (Tibet) Region. The area of the most frequent occurrence of dust storms and floating-dust is in South Xinjiang Region, and of wind-blown sand in the Hexi Region. In general, the frequency of dust events in all the seven regions shows a decreasing tendency from 1954 to 2000, but there are certain differences between various dust events in different regions. The maximum interannual change and variance of dust events during this time happened in South Xinjiang Region and Hexi Region. The dust events generally occur most frequently in April in most parts of China. The spring occurred days of dust events occupied 60-70% of the whole year in Hetao Region and Northeastern China Region. However, in South Xinjiang Region and North Xinjiang Region, which was less affected by monsoon climate, dust events may occur at any time of the year, less than 50% of the events in this region occur during spring. In the remaining three regions 50-60% of the dust events occur in spring of a year.     

红外光谱定量比较分析法及其应用

利用红外光谱定量比较分析的原理，从定向及微区的角度研究晶化固态物质的成分、结构等，有效地解决矿物、岩石、矿床乃至构造研究中的诸多问题。     

义敦成矿带铜银铅锌锡矿产资源调查评价进展与潜力

义敦成矿带地处独特的大地构造部位，经历了复杂的地质构造演化和强烈的岩浆活动，成矿条件优越，矿产资源丰富。1999年实施国土资源地质大调查以来，相继发现了普朗、松诺、卓玛斑岩铜矿；砂西、热朗泽、夏隆等银铅锌矿；热隆、脚根玛锡矿；打马池觉铜金矿等一批具有重要找矿前景的矿床(点)。该地区矿产资源勘查工作程度低，蕴藏着较大的找矿潜力，有望成为国家级重要的有色及贵金属矿产勘查和开发基地。     

SOIL CONSERVATION EFFICIENCY OF DIFFERENT MODELS CONVERTING FROM STEEP FARMING SLOPE PLOTS IN YA''''AN, SICHUAN, CHINA

Converting farming slope land into artificial forestland or grassland is a major measure of soil/water conservation. Five conversion practices, namely, 1) a control plot still tilled with a crop (maize), 2) a folder grass-growing plot seeded with Lolium perenne , 3) a young alder tree-growing plot, 4) a pear orchard plot and 5)a bamboo plot intercropped with folder grass, were monitored to compare the soil conservation efficiency of those changes in Ya'an, Sichuan for 3 years between September 1998 and August 2001. Results showed that the 5 designed converting models functioned differently in erosion control. The most effective model was bamboo groves intercropped with folder grass (Lolium perenne). The folder grass (Lolium perenne) growing model was more effective than the pure pear orchard model. The least effective model was the young alder tree-growing slope, which was even less effective than the control (a slope without converted cultivation). Meanwhile, changes in the soil's physical properties r     

盐渍土与分散性针孔试验影响

通过具体实例,研究了新疆氯盐渍、硫酸盐渍土对针孔试验的影响,认为氯盐渍土因其胶结作用,随着盐量的增加,土样孔径大小、流量变化不大。硫酸盐渍土因其膨胀性,随着盐量的增加,土样孔径、流量减小,对土样的冲蚀破坏作用而不相同。     

洪家渡水电站左坝肩高边坡稳定及加固措施研究

贵州洪家渡水电站左坝肩高边坡开挖高度310 m,采用弹塑性有限元数值模拟方法对左坝肩高边坡施工期岩体应力应变状态进行分析研究,并结合现场变形观测资料对计算结果进行验证,从而对左坝肩高边坡的稳定性进行评价并提出相应的加固措施。     

黑龙江省湿地资源遥感信息解译分析

按黑龙江省湿地分类标准，应用资源卫星遥感技术，建立湿地资源解译标准，判别分析全省湿地资源现状与区域分布。     

利用GPS资料浅析华北地区块体运动及与地震活动的关系

为了研究华北地区近年地壳水平运动的状态与演化．利用10a来华北地区网络工程、山西断裂带GPS观测成果．结合该区地质构造背景．分析了华北地区各块体运动的方向、速率变化及其与区内所发生地震的关系．初步得出以下结论：在区域应力场相对稳定时，表现为区域内GPS观测点整体趋势性运动不明显；而在区域应力场相对变化时．表现为影响区域内GPS观测点出现明显的整体趋势性运动。     

Timing and geochemical characters of the Sanchazi magmatic arc in Mianlüe tectonic zone, South Qinling

The Sanchazi mafic-ultramafic complex in Mianlue tectonic zone, South Qinling can be subdivided into two blocks, i.e. Sanchazi paleo-magmatic arc and Zhuangkegou paleo-oceanic crust fragment (ophiolite). The Sanchazi paleo-magmatic arc is mainly composed of andesite, basaltic and basalt-andesitic gabbro (or diorite), andesitic dyke, plagiogranite and minor ultramafic rocks, which have typical geochemical features of island arc volcanic rocks, such as high field strength element (e.g. Nb, Ti) depletions and lower Cr, Ni contents. The Light rare earth element (LREE) and K enrichments of these rocks and zircon xenocrystals of 900 Ma from plagiogranite suggest that this magmatic arc was developed on the South active continental margin of the South Qinling micro-continent. The U-Pb age of (300 ± 61)Ma for zircons from plagiogranite indicates that the Mianlue paleo-oceanic crust was probably subducted underneath the South Qinling micro-continent in Carboniferous. This is consistent with the formation time (309Ma) of the Huwan eclogite originating from oceanic subduction in Dabie Mountains, suggesting that the Mianlue paleo-ocean probably extended eastward to the Dabie Mountains in Carboniferous. The high-Mg adakitic rocks in Sanchazi paleo-magmatic arc suggest that the subducted oceanic crust was relatively young (＜25Ma) and hot.     

A new method for testing pile by sin- gle-impact energy and P-S curve

Introduction Through many year's practices by vast numbers of scientific and technological workers andefforts from all aspects, the dynamic testing method of high-low strain has formally entered intothe technical code of foundation pile test of construction at last (The Industry Standards of thePeople's Republic of China, 2003). The striking mode of the dynamic testing method of high strainis stipulated as hammer in the code, the striking of rocket can also be used. The latter is widely…