中国大陆现今垂直形变特征的初步探讨

利用GPS观测资料进行大范围的垂直形变特征研究是本文研究的重点。通过网络工程基准站和基本站的GPS观测资料，绘制了中国大陆的垂直速率等值线图像，并对中国大陆垂直运动特征进行了定性的分析，结果表明：中国大陆垂直运动在70％以上的区域表现为沉降运动，在青藏高原和除北京外的整个华北块体及燕山块体的垂直运动表现为隆升的趋势。中国大陆西北和东南、西南和东北的整体垂直运动呈一种斜对称状态。对基于GPS观测所得的等值线图与基于水观测所得的等值线图进行了比较，比较结果显示，除了华南块体外，二者在整体趋势上比较一致。     

General Entropy Model of Line Segments Uncertainty in GIS

Spatial data uncertainty can directly affect the quality of digital products and GIS-based decision making. On the basis of the characteristics of randomicity of positional data and fuzziness of attribute data, taking entropy as a measure, the stochastic entropy model of positional data uncertainty and fuzzy entropy model of attribute data uncertainty are proposed. As both randomic-ity and fuzziness usually simultaneously exist in linear segments, their omnibus effects are also investigated and quantified. A novel uncertainty measure, general entropy, is presented. The general entropy can be used as a uniform measure to quantify the total un-certainty caused by stochastic uncertainty and fuzzy uncertainty in GIS.     

Seasonal Variations of the East Asian Subtropical Westerly Jet and the Thermal Mechanism

The seasonal variations of the intensity and location of the East Asian subtropical westerly jet (EAWJ) and the thermal mechanism are analyzed by using NCEP/NCAR monthly reanalysis data from 1961 to 2000. It is found that the seasonal variation of the EAWJ center not only has significant meridional migration, but also shows the rapid zonal displacements during June-July. Moreover, there exists zonal inconsistency in the northward shift process of the EAWJ axis. Analysis on the thermal mechanism of the EAWJ seasonal variations indicates that the annual cycle of the EAWJ seasonal variation matches very well with the structure of the meridional difference of air temperature, suggesting that the EAWJ seasonal variation is closely related to the inhomogeneous heating due to the solar radiation and the land-sea thermal contrast. Through investigating the relation between the EAWJ and the heat transport, it is revealed that the EAWJ weakens and shifts northward during the warming period from wintertime to summertime, whereas the EAWJ intensifies and shifts southward during the cooling period from summertime to wintertime. The meridional difference of the horizontal heat advection transport is the main factor determining the meridional temperature difference. The meridional shift of the EAWJ follows the location of the maximum meridional gradient of the horizontal heat advection transport. During the period from April to October, the diabatic heating plays the leading role in the zonal displacement of the EAWJ center. The diabatic heating of the Tibetan Plateau to the mid-upper troposphere leads to the rapid zonal displacement of the EAWJ center during June-July.     

Study on the Overfitting of the Artificial Neural Network Forecasting Model

Because of overfitting and the improvement of generalization capability (GC) available in the construction of forecasting models using artificial neural network (ANN), a new method is proposed for model establishment by means of making a low-dimension ANN learning matrix through principal component analysis (PCA). The results show that the PCA is able to construct an ANN model without the need of finding an optimal structure with the appropriate number of hidden-layer nodes, thus avoids overfitting by condensing forecasting information, reducing dimension and removing noise, and GC is greatly raised compared to the traditional ANN and stepwise regression techniques for model establishment.     

The Gas Resources Assessment Expert System of the Songliao Basin

The gas resources assessment expert system is one of the advanced methods for appraising oil and gas resources. The establishment of a knowledge base is the focal task in developing the expert system. This paper presents a summary of the mechanism and the major controlling factors in the formation of gas pools in the southeast uplift of the Songliao basin. Then an appropriate assessment model is established for trapping the gas resources and a knowledge base built in the expert system to realize the model. By using the expert system to appraise the gas-bearing probability of 25 major traps of the Quantou and Denglouku Formations in the Shiwu-Dehui area, the authors have proved that the expert system is suitable for appraising traps in the Songliao basin and similar basins.     

成都平原传统场镇与林盘居民点的分布特征及其影响因素——以成都郫县为例

基于近现代地图与相关地理信息，结合历史文献与实地考察，通过GIS空间分析、核密度估算、欧氏距离、基尼系数等方法，以传统林盘聚落的核心区成都郫县为例，定量揭示了1947、1970、1985、2000与2018年郫县林盘居民点的空间分布特征与场镇分布关系的变化情况。结果表明：1）不同时期林盘居民点的分布具有明显的空间差异性，在改革开放前，林盘居民点的分布极易受到政治经济中心的影响，在改革开放后，其具有均质化快速发展的特点，但城镇化的快速推进从根本上改变了林盘居民点的散居特征，其聚集程度明显增高。林盘居民点高密度区始终具有围绕传统场镇及城镇建成区分布的特点。2）传统场镇的市场半径大致为3 km，交通条件是其选址的首要因素，民国时期场镇选址主要受水路交通影响，建国后水路交通为场镇带来的交通便利逐渐被陆路交通所取代。3）传统场镇的分布会随着林盘居民的自组织行为与相关政策的调控而不断趋于均衡状态，但在改革开放之后，场镇由乡村市场驱动的自由放任式发展转变为地方政府驱动下的固定场所。4）林盘居民点具有沿河流水系分布的特点；传统时期林盘居民点与主要道路之间的关联性较低，但当前其具有沿道路分布的特点。     

一种基于分步式滤波的多传感器组合导航系统算法研究

提出了一种多传感器组合导航系统的分步滤波算法。当所有传感器的观测值到来时,首先对该时刻的系统状态进行预测,然后利用常规卡尔曼滤波器和各导航传感器的观测值依次对该时刻的状态向量估计值进行更新,进而得到该时刻状态向量基于全局信息的最优融合估计。最后利用GPS/SST/高度表/SINS多组合导航系统对上述算法进行验证。仿真结果表明,该算法与集中式卡尔曼滤波算法的估计精度相同,但计算量得到降低。     

广义点摄影测量在建筑物立面轮廓重构中的应用

采用广义点摄影测量理论对建筑物立面框架轮廓进行重构。广义点是对当代线摄影测量以及无穷远点（灭点）理论的升华。实验结果表明,采用线面基元进行立面重构相比于经典的点云重构方法,不仅简洁、高效,还能获得清晰的三维边缘轮廓,且自动化程度较高。     

An Examination of ENSO’s Effect on the Monthly and Seasonal Climate of Hong Kong from a Statistical Perspective

This study aims to examine the effect of El Nino and La Nina on the monthly and seasonal climate of Hong Kong against the ENSO-neutral situation from a statistical perspective. Monthly and seasonal temperature and rainfall of Hong Kong and monthly number of tropical cyclones (TCs) coming within 500 km of the city over the 59-yr (1950-2008) period are examined under three ENSO situations, namely El Nino, La Nina, and ENSO-neutral. It is found that, compared with the ENSO-neutral situation, El Nino tends...     

某首层柱顶隔震结构动力特性测试研究

为了达到隔震设计的目的并检验隔震层的工作性能,测试分析了采用首层柱顶隔震技术的某五层框架结构在环境激励和初位移条件下的动力特性,得到了结构的前3阶自振特性如自振频率、振型和阻尼比;分析了初位移条件下隔震层的自由衰减曲线和滞回性能.结果表明:环境激励条件下,隔震结构与非隔震结构动力特性相近,隔震结构在正常使用状态下具有足...