大兴安岭森林覆盖区植物化探找矿方法研究   总被引：1，自引：0，他引：1  

权恒  张宏  张炯飞  武广  李广远  王录  金成洙 《地质与资源》1998,7(4):241-249

根据前人在植物化探方面的研究成果,结合本区有色、贵金属矿化实际,选择了白桦树树干下部树皮为植物化探样品,进行了Au、Ag、Cu、Pb、Zn元素的测试.结果表明：①该区植物化探工作比土壤化探更具优越性;②白桦树树皮具有易采、易灰化的特点;③植物化探结果,可良好地反映出已知的Au、Pb、Zn矿化-蚀变带.用植物化探方法找矿,在该区具有良好的适用性和可靠性,有一定的推广价值.  相似文献   

甘肃敦煌地区太古宙孔兹岩系特征   总被引：5，自引：0，他引：5  

于海峰  梅华林  李铨 《华北地质》1998,21(1):19-25

本文根据甘肃敦煌地区广泛出露在太古宙TTG杂岩中的一套副变质岩系的岩石组合、典型矿物组合、变质相特征和岩石化学特征的分析,认为它们是一套中深变质的碎屑岩-泥质岩-泥灰岩-碳酸盐建造,其中夹有少量的变质基性火山岩。原岩形成于具有基性火山作用的活动大陆边缘滨海-浅海环境。经过太古宙的区域高角闪岩相变质作用,形成孔兹岩系。  相似文献   

直达波法测定整板基础砼强度     

周全  谌和平 《江西地质》1998,12(1):68-69

本文以某工程为例,介绍了直达波法测定整板基础砼强度的技术方法;其结果可避免以往回弹法测量结果离散度较大而引起的争议。  相似文献   

双曲面模型深海三维定位数据模拟及精度分析          下载免费PDF全文

朱祥娥  蔡艳辉  王权 《海洋测绘》2008,28(6):6-9

结合声波射线传播规律提出了双曲面模型水声定位的数据模拟方法。利用该方法模拟一定浮标网形下声源位于某区域约2 000m水深处10km×10km范围内的声线双曲面模型定位观测数据,进行定位解算,并将截止角的概念引入水声定位中。定位结果显示,大部分区域水下DGPS定位系统的外符合定位精度在水平方向优于5m,垂直方向优于10m;网形中间区域精度较高,三维定位精度为亚米级。引入角度限制后,定位区域内外符合定位精度水平方向优于1m,垂直方向优于4m。  相似文献   

一种空间域矢量地图数据盲水印算法   总被引：2，自引：2，他引：0  

王超  王伟  王泉  秦前清 《武汉大学学报(信息科学版)》2009,34(2)

对目前已有的针对二雏矢量数据的水印算法进行了分析,并提出了一种新的鲁棒的盲水印算法.该算法首先将矢量数据分块,然后在不同分块中,结合密钥修改某些点的x坐标或者y坐标,从而嵌入水印信息.实验证明,该算法对平移、坐标转换、制图综合、插值等常规操作以及地物对象顺序置乱等攻击具有较好的鲁棒性,并且是一种盲检算法,具有较好的实用价值.  相似文献   

Distribution of nutrients and eutrophication assessment in the Bohai Sea of China   总被引：5，自引：1，他引：4  

王修林  崔正国  郭全  韩秀荣  王江涛 《中国海洋湖沼学报》2009,27(1):177-183

Water samples were collected in 120 stations in the Bohai Sea of China to analyze the distribution of dissolved nutrients and assess the degree of eutrophication in August 2002. The result shows that the average concentration of DIN increased and the PO4-P concentration sharply decreased compared to the previous data of corresponding period. The high concentrations of DIN and PO4-P occurred in coastal waters, especially in the bays and some river estuaries, while the high concentrations of SiO3-Si in the surface and middle depth occurred in the central area of the Bohai Sea. The average ratio of DIN/ PO4-P was much higher than the Redfield Ratio (16:1). Apparently, PO4-P was one of the limiting nutrient for phytoplankton growing in the sea. The average concentrations of DON and DOP were higher than their inorganic forms. The results of eutrophication assessment show that 22.1% of all stations were classified as violating the concentration levels of the National Seawater Quality Standard (GB 3097-1997) for DIN and only 3.9% for PO4-P. The average eutrophication index in the overall area was 0.21±0.22 and the high values occurred in Bohai Bay, Liaodong Bay and near the Yellow River estuary. This means that the state of eutrophication was generally mesotrophic in the Bohai Sea, but relatively worse in the bays, especially some river estuaries.  相似文献   

快速城市化地区建设用地演变驱动力研究——以深圳市龙岗区为例     

杨明  郭仁忠  李全 《武汉大学学报(信息科学版)》2009,34(2)

在综述国内LUCC驱动力研究的基础上,确定了驱动因子.以深圳市龙岗区为例,基于非线性的Logistic模型,分析研究了建设用地演变的驱动力.  相似文献   

RR Lyrae stars and the horizontal branch of NGC 5904 (M5)     

A. Arellano Ferro  A. Luna  D. M. Bramich  Sunetra Giridhar  J. A. Ahumada  S. Muneer 《Astrophysics and Space Science》2016,361(5):175

  相似文献   

Excess commuting in transitional urban China: A case study of Guangzhou   总被引：1，自引：0，他引：1  

Wangbao Liu  Quan Hou 《中国地理科学(英文版)》2016,26(5):599-608

During the reform era, Chinese cities witnessed dramatic institutional transformation and spatial restructuring in general and profound change of commuting patterns in particular. Using household surveys collected in Guangzhou, China, in 2001, 2005 and 2010, excess commuting measurements are estimated. Excess commuting shows an overall trend of increasing during 1990–1999, and then declining during 2000–2010. We argue that deepening marketization of the jobs and housing sectors has induced spatial separation of jobs and housing. In other words, institutional transition and urban spatial restructuring are underpinning the changes of commuting patterns in Chinese cities. Excess commuting has strong relationship with individual socio-demographic status, which is by and large due to the increasing flexibilities of jobs and housing location choices enjoyed by urban residents. The findings call for considerations on balancing jobs-housing in making public policies relevant to urban development in general, and land use and transportation in particular.  相似文献   

Secular period decreasing of detached chromospherically active binaries     

Chang Qing Luo  Xiao Bin Zhang  Li Cai Deng  Yang Ping Luo  Zhi Quan Luo  Shu Zheng Yang 《Astrophysics and Space Science》2010,327(1):9-17

The long-term orbital period changes of a large sample of detached chromospherically active binaries (CABs) were studied. Eleven such systems were found to be undergoing secular period decreases with the rates of ?6.3×10^?9 to ?1.1×10^?6 days per year. The period decreasing rates are found to vary depending on the orbital period. The longer the orbital period is, the more rapidly the period decreases. Following Stepien (Mon. Not. R. Astron. Soc. 274:1019, 1995), the period decreasing rate predicted by angular momentum loss (AML) caused by magnetic wind is computed for each system. A comparison between the observed and calculated period decreasing rates shows that the former values are obviously larger than the latter by 1–3 orders of magnitude. It suggests that the magnetic wind is not likely the determinant mechanism driving the AML in these systems. Finally, the orbital angular momentum (AM) and the rate of AML, $\dot{J}$ , are computed for each system. It shows that the AM have a similar change with the orbital period like dP/dt does, but $\log\dot{J}/J$ presents no strict changing with the kinematical ages.  相似文献