地面网与空间网联合平差中起算边长和起算方位角权的确定

本文全面分析了拉普拉斯方位角和起算边长的精度，指出了联合平差中这两类元素不能作为固定值，而应视为变量且赋予相应的权，并对权的取法进行了探讨。     

1962—1986年JYD1968.0地极坐标的均匀化及其与BIH的比较

本文研究了１９６２－１９８６年ＪＹＤ１９６８．０地极坐标均匀中星表系统差，章动系列的变动和光行星常数变动的影响，并将经过改正后的ＪＹＤ１９６８．０地极坐标系统和ＢＩＨ系统作了比较。     

Study on Sampling Rule and Simplification of LiDAR Point Cloud Based on Terrain Complexity

It is difficult to obtain digital elevation model (DEM) in the mountainous regions. As an emerging technology, Light Detection and Ranging (LiDAR) is an enabling technology. However, the amount of points obtained by LiDAR is huge. When processing LiDAR point cloud, huge data will lead to a rapid decline in data processing speed, so it is necessary to thin LiDAR point cloud. In this paper, a new terrain sampling rule had been built based on the integrated terrain complexity, and then based on the rule a LiDAR point cloud simplification method, which was referred as to TCthin, had been proposed. The TCthin method was evaluated by experiments in which XUthin and Lasthin were selected as the TCthin’s comparative methods. The TCthin’s simplification degree was estimated by the simplification rate value, and the TCthin’s simplification quality was evaluated by Root Mean Square Deviation. The experimental results show that the TCthin method can thin LiDAR point cloud effectively and improve the simplification quality, and at 5 m, 10 m, 30 m scale levels, the TCthin method has a good applicability in the areas with different terrain complexity. This study has theoretical and practical value in sampling theory, thinning LiDAR point cloud, building high-precision DEM and so on.     

Evaluating urban public facilities of Shenzhen by application of open source data

Abstract

This article applies open source data of public facilities through data mining, not only to evaluate the public facilities from an objective dimension, but also to reflect the sensory opinions of the group factually, eventually realizing the evaluation measurement of urban public facilities. The research takes Shenzhen city as an empirical case and chooses typical public facilities to mine data, resolve address and weight to explore the application of public facilities evaluation under dimension reduction of open source data. The empirical study consists of three parts. First, as the objective evaluation, we estimate the density distribution and per capita of public facility through data mining and address resolution. Second, as the subjective evaluation, we carry on the location analysis to high-score public facility through attention and satisfaction data of Internet evaluation. Finally, as mentioned above, we calculate the weight of objective and subjective evaluation of public facility, eventually formatting the comprehensive evaluation of public facilities.     

人工心肺机流量计的研制

本文介绍了如何应用单片微型计算机和光电传感器组成人工心肺机(或称体外循环机)流量计。该仪器对人工心肺机的泵的各种转速能够准确地采集,对不同的患者能够精确地计算出所需血液流量,从而定量地控制输送给病人的血液流量,以保证心脏手术顺利进行,改变了临床手术时手工计算的落后情况。流量计是一台新型的智能化仪表。     

Multi-objective optimal second order design of networks

Nearly all work on the optimal design of networks has been confined to single objective optimal design. Less attention has been paid to multi-objective optimal design where one must simultaneously optimize precision, reliability and other quantities. This paper discusses the concept of multi-objective optimal second order design of networks and its properties, which proves very different from that of single objective optimal design. To demonstrate its applications, a levelling network located in an earthquake area in the north east of China is taken as an example. The result shows in this case that multi-objective optimal design is optimal from the point of view of total objectives.     

Exploring the spatial and temporal dynamics of land use in Xizhuang watershed of Yunnan, southwest China

Over the last two decades, China has introduced a series of agricultural and forestland use reforms, aiming to feed the largest population in the world and maintain ecological services locally and nationally. This paper studies the impacts of local government-driven reforestation on land use and land cover change, as well as its further impacts on livelihoods of upland farmers in Xizhuang watershed. An analysis of aerial photographs and ASTER satellite imagery from 1987 to 2002, respectively, showed that the forest has significantly increased at the expense of decreasing farmland. However, the monoculture reforestation of pine has caused both biophysical and socio-economic consequences. This case study also shows forestry decentralization in China remains incomplete. Land use and land cover change is also a political economic issue. Some of the reforms designed to protect forest resources have had a negative impact on rural livelihoods.     

干旱区地下水位降幅空间分布特性研究

基于GIS和地理统计学的理论、方法对所取观测井地下水位降幅数据进行空间分布特征分析。结果表明:数据服从正态分布,结构符合球状模型,空间数据存在东西方向和南北方向的二价函数趋势;地下水位降幅由北向南呈环状递减,最深降幅达30m,绿洲群大部分居于20～30m降幅之间,为地下水开采密集区,大于10m降幅的面积约69300hm2。利用Kriging最优内插法生成等值线图,可以更准确和直观地展示整个研究区的地下水资源状况、生态环境可能发生退化的区域及未来发展方向。     

论光电测距仪的周期误差和相位不均匀性误差

论述了测距仪周期误差及相位不均匀性误差的性质,分析了这些误差对距离测量的影响,给出了实验结果,提出了改进有关误差检定的建议。     

线性综合模型用于崩滑体变形预报的研究

综合分析和比较了自回归模型和回归模型的特点,提出了采用线性综合模型来预报崩滑体变形的思想,以弥补自回归模型或回归模型预报的不足。实测资料的处理结果表明,综合线性模型具有特别的适用性。