局部三维大地网的平面坐标与高程坐标的精度分析

本文从理论和实际两方面讨论了局部三维网的平面坐标与高程坐标的精度,分析了平面坐标与高程坐标的相关性问题,并用一局部测边三维网,计算和分析了测边三角高程在什么情况下能代替等级水准测量。     

Automatic Change Detection for Road Networks from Images Based on GIS

Up to now, detailed strategies and algorithms of automatic change detection for road networks based on GIS have not been discussed. This paper discusses two different strategies of automatic change detection for images with low resolution and high resolution using old GIS data, and presents a buffer detection and tracing algorithm for detecting road from low-resolution images and a new profile tracing algorithm for detecting road from high-resolution images. For feature-level change detection (FL-CD), a so-called buffer detection algorithm is proposed to detect changes of features. Some ideas and algorithms of using GIS prior information and some context information such as substructures of road in high-resolution images to assist road detection and extraction are described in detail.     

网状河流研究进展述评

网状河流作为一种新的冲积河流类型已经引起地貌学家、水利学家和沉积学家的关注 ,成为河流地貌领域、河流沉积领域以及河流水动力领域的研究热点之一。本文在介绍网状河流基本概念的基础上 ,综合国内外的研究成果 ,从河流的平面形态、边界条件、沉积特征、水动力条件以及在河型演化序列中的位置等方面 ,对网状河流的研究进展作一较全面的述评 ,并指出目前研究的薄弱环节 ,以利于研究者把握网状河流的研究现状 ,并推动对网状河流的进一步探讨。     

中国气候过渡带干旱化发展趋势与东亚夏季风、极涡活动相关研究

利用国家气候中心1961~2000年中国160个测站降水量和NCEP/NCAR全球再分析资料,采取线性趋势变化、相关和水汽输送等分析方法,揭示中国大陆40 a的年和季降水变化趋势显著区域的时空分布特征,探讨与东亚夏季风和极涡活动的某些相关。结果表明:(1)经内蒙古中东部、山西省、河南省、陕西省和甘肃省东部至湖北省西部、四川省西北部和重庆市年降水量线性下降趋势较显著(其中相当部分为中国的气候过渡带),并明显向东与华北大部、东北地区中南部、环渤海地区、山东省和江苏省北部线性下降较显著区连成一片,构成占中国国土面积约1/5的气候变化干旱化区域,其中20世纪90年代年平均降水量负距平为50~100 mm的面积约达90万km2,其季节变化主要为夏、秋两季降水锐减,长江中下游、东南部沿海和广东省大部年降水量线性上升趋势显著,其中江西省20世纪90年代年降水量正距平在200 mm以上;(2)20世纪90年代夏季1000~300 hPa水汽输送积分负距平区与中国40 a气候变化干旱化区域总体相吻合;(3)中国西部地区东部与华北、东北地区中南部、环渤海地区降水干旱化区域连成一片,原因是多方面的,文中初步揭示了与影响中国的东亚夏季风在30°N以北地区活动和太平洋区极涡强度指数自20世纪70年代前后减弱相关显著。     

龙岗金垅顶子近代活动火山的岩石学与地球化学

距今１６００ 年前喷发的金龙顶子火山是龙岗火山群中一座最年轻的近代活动火山, 它的喷发物包括金龙顶子火山锥体 （海拔９９９．４ｍ ）、熔岩流及其广布的火山碎屑席 （四海火山渣层）。金龙顶子火山岩为单一的粗面玄武岩, 有着极为相似的ＲＥＥ和不相容元素分布模式, ８７Ｓｒ／８６Ｓｒ和１４３Ｎｄ／１４４Ｎｄ 分别变化于０．７０４８４６～０．７０４９２１ 和０．５１２６１９～０．０．５１２６４６, 这反映了它们直接来自地幔源区, 岩浆上升过程极少演化和壳源混染, 具有较为原始的岩浆特点。年轻火山岩中的幔源捕虏体提供了该区存在相对低温 （～９００℃） 含水的地幔。     

青色草原种畜场硅藻土矿地质特征及前景展望

青色草原种畜场硅藻土矿产于以更新世玄武岩为基底的盆地中,硅藻土矿体呈近水平层状产出,总体形态为偏长的透镜体。区内有优质的硅藻土及硅藻粘土两个品级矿石。据孢粉及硅藻化石研究可知矿床形成于晚更新世温干的浅水环境。矿区硅藻土品质优良,有良好的发展前景。     

Effects of non-submerged boulder on flow characteristics – A field investigation

The effect of fully submerged boulders on the flow structure in channels has been studied by some researchers. However, many natural streams have bed material with boulders that are not fully submerged under water. In many natural streams, boulders cover between 1% and 10% of the area of the stream reach. The effect of non-submerged boulders on the velocity profile and flow characteristics is very important for assessing riverbed deformation. The objectives of this paper are to find the pattern of velocity distribution around a non-submerged boulder and to compare it with the classical studies on flow resistance and Reynolds stress distribution in open channels. Also, by considering the variation in the Reynolds stress distribution at different locations around a non-submerged boulder, the effect of a non-submerged boulder on the estimation of shear velocity and resistance to flow has been investigated. Results indicates that inside the scour hole caused by a non-submerged boulder in a river velocity distributions are irregular. However, velocity distributions are regular outside the scour hole. The presence of the boulder causes a considerable deviation of the Reynolds shear stress from the classic distribution, showing a non-specific distribution with negative values. The classical methods for calculating shear velocity are not suitable because these methods do not give detailed velocity and Reynolds stress distributions in natural rivers with a lot of boulders. Thus, the effect of a non-submerged boulder on the estimation of the resistance to flow by considering the variations in velocity and Reynolds stress distributions at different locations around a non-submerged boulder is important and needs to be studied in a natural river instead of just in laboratory flumes. The negative values in Reynolds stress distribution around a boulder indicate that the classical methods are unable to predict resistance to flow, and also show strong turbulence inside the scour hole where the complex flow conditions present ambiguous Reynolds stress distributions. In the current study, to obtain a reasonable estimation of parameters in natural rivers, the classical method has been modified by considering velocity and Reynolds stress distributions through the boundary layer method.     

文登市农村集体建设用地整理调查报告

世界银行与国土资源部共同实施的“中国经济改革实施”子项目“农村集体建设用地管理利用政策研究”调研工作在文登市展开。为配合专家组调研,根据国土资源部《农村集体建设用地管理利用的政策研究项目报告书》,文登市国土资源局于2007年1月至3月中旬,就农村集体建设用地整理子课题进行了详细的调查和分析,基本摸清了文登市农村集体建设用地整理的现状及潜力。     

沂源县耕地资源现状及保护对策分析

沂源县是典型的山区农业县,目前耕地面积日益减少,人地矛盾日趋尖锐,耕地保护面临着较大的压力。为有效保护耕地资源,在对该县耕地资源质量和耕地后备资源现状进行了分析的基础上,提出加大土地开发整理力度、加强基本农田保护和加快中低产田改造等耕地资源保护与可持续利用对策。     

Cloning and analysis of phycoerythrin genes inGracilaria Lemaneiformis (Rhodophyceae)

Cloning and sequencing of the genes coding for the α- and β- subunit of phycoerythrin (PE) of a red alga—Gracilaria lemaneiformis (GL) are reported. Alignment of 1084 nucleotides sequenced with three known red algal PE genes,Rhodella violacea (RV),Polysiphonia boldii (PB) andAglaothamnion neglectum (AN), showed high level of conservation, and similarities of 77,6% (between GL and RV), 77.9% (GL and AN) and 79.0% (GL and PB). The similarities of amino acids were 84.8% (between GL and RV), 85.7% (GL and PB), and 80.6% (AN and GL), higher than those among nucleotides. Project 39670405 supported by NSFC and Japanese Science Promotion Society (JSPS).