Basic research on key techniques related to urban 3D pipe network modeling

A new geometric modeling approach is introduced in this paper. First the principle of modeling of 3D pipe network is discussed in detail. Then the procedures of implementing pipe network visualization and system functions are presented. Last, several efficient methods for speeding up display of graphics are introduced. The new geometric modeling approach offers to people a new way to solve 3D visualization of complex urban pipe network.     

An algorithm for automatic cartographic sounding selection

Soundings on nautical charts provide information about the shape of ocean bottom between chart depth curves. A single chart may have thousands of soundings posted on it. This paper describes a new algorithm for selecting soundings automatically. At first, the problem encountered in automatic cartographic sounding selection is presented. Then the authors give the principle of the new algorithm, and the implementation is illuminated in detail. At last the experiments prove the rationality and efficiency of the new algorithm.     

Architecture of HLA based distributed virtual geographic environment

Integrating the theory of distributed virtual geographic enviroments (DVGE) and high level architecture(HLA), the architecture of DVGE based on HLA is designed. The data flow and the object models of the architecture are also discussed. The architecture basically meets the need of DVGE in real-time communication, distribution, collaboration, reusing and interoperation, expansion, and standard.     

Shape similarity measures of linear entities

The essential of feature matching technology lies in how to measure the similarity of spatial entities. Among all the possible similarity measures, the shape similarity measure is one of the most important measures because it is easy to collect the necessary parameters and it is also well matched with the human intuition. In this paper a new shape similarity measure of linear entities based on the differences of direction change along each line is presented and its effectiveness is illustrated.     

A construction schema for provincial spatial database of China

In order to provide a provincial spatial database, this paper presents a scheme for spatial database construction to meet the needs of China. The objective and overall technical route of spatial database construction are described. The logical and physical database models are designed. Key issues are addressed, such as integration of multi-scale heterogeneous spatial databases, spatial data version management based on metadata and integrative management of map cartography and spatial database.     

阿图什市5.2级地震与于田6.2级地震前兆异常分析

利用阿克苏台网中心前兆观测数据,采用动态分析、形态法对新疆阿图什市Ms5.2地震和于田县Ms6.2地震进行系统分析.发现两次地震前,阿合奇台地倾斜资料、乌什台水管倾斜资料、伸缩仪资料、体应变及辅助测项钻孔水位和静水位数据、地电数据均出现明显的震前异常.其中水管仪、伸缩仪、体应变、地倾斜表现为打破年变,水管仪震前几天出现高频抖动、日变形态畸变;体应变辅助测项钻孔水位和静水位、地电震前表现为突变.     

前兆远程子台CDMA传输故障诊断及排除

本文简要介绍了CDMA传输技术及其在地震前兆远程子台的应用,之后以天津市地震局宝坻地震台的远程子台为实例,对地震前兆远程子台CDMA传输中的故障原因进行了研究,指出导致CDMA传输故障的原因主要有:仪器通讯部分故障、资费余额不足、路由器"假死"、路由器死机、路由器内部故障(特别是SIM卡接触不良)、CDMA信号强度不够、交换机故障、传输硬件连接断路等。在此基础上提出了一套行之有效的故障诊断流程,并对常见故障原因的判定和排除方法做了归纳整理。本文对使用CDMA传输方式或其他无线传输方式的地震前兆远程子台的维护管理人员有一定的参考意义。     

中原经济区“三化”协调发展水平的时空特征研究

基于2001-2010年中原经济区的主体河南省各地级市“三化”发展的数据,采用熵权法对中原经济区“三化”协调发展水平进行测度,进而分析其时序和空间特征.结果表明:从时间序列看,中原经济区的“三化”协调发展水平呈现提高趋势.从空间格局上看,“三化”协调发展水平空间分异明显,呈现出以中原城市群为主体的中部地区较高、南北地域略低的特征,且其与各个地域“三化”各自的发展水平的接近度密切相关.这就要求在制定政策的过程中,不能简单地根据地域性质和经济发展水平判断“三化”协调发展水平,更应注重探测“三化”各自发展水平的接近度.     

Driving forces analysis of reservoir wetland evolution in Beijing during 1984–2010

The reservoir wetland, which is the largest artificial wetland in Beijing, constitutes one of the important urban ecological infrastructures. Considering two elements of natural environment and socio-economy, this paper established the driving factor indexing system of Beijing reservoir wetland evolution. Natural environment driving factors include precipitation, temperature, entry water and groundwater depth; social economic driving factors include resident population, urbanization rate and per capita GDP. Using multi-temporal Landsat TM images from 1984 to 2010 in Beijing, the spatial extent and the distribution of Beijing reservoir wetlands were extracted, and the change of the wetland area about the three decade years were analyzed. Logistic regression model was used to explore for each of the three periods： from 1984 to 1998, from 1998 to 2004 and from 2004 to 2010. The results showed that the leading driving factors and their influences on reservoir wetland evolution were different for each period. During 1984-1998, two natural environment indices： average annual precipitation and entry water index were the major factors driving the increase in wetland area with the contribution rate of Logistic regression being 5.78 and 3.50, respectively, and caused the wetland growth from total area of 104.93 km 2 to 219.96 km 2 . From 1998 to 2004, as the impact of human activities intensified the main driving factors were the number of residents, groundwater depth and urbanization rate with the contribution rate of Logistic regression 9.41, 9.18, and 7.77, respectively, and caused the wetland shrinkage rapidly from the total area of 219.96 km 2 to 95.71 km 2 . During 2004-2010, reservoir wetland evolution was impacted by both natural and socio-economic factors, and the dominant driving factors were urbanization rate and precipitation with the contribution rate of 6.62 and 4.22, respectively, and caused the wetland total area growth slightly to 109.73 km 2 .