不同经验太阳光压模型对于北斗卫星定轨的适用性分析

当前的北斗卫星导航系统尚缺乏合适的太阳光压模型,由GPS的ECOM模型衍生而来的多种经验光压模型常被用于北斗定轨中。从观测值残差、轨道内、外符精度以及外推精度等方面比较分析了目前常用的4种经验光压模型对于北斗卫星定轨的适用性。结果表明,不同(类型)卫星适用不同的经验光压模型,但总体来看,9参数模型的适用性最差,而5参数和7参数模型的适用性相对较好。     

泥沙捕集器在长江口航槽区域放投放和观测

本文报道了５套泥沙捕集器在１９８７年８月１３－１７日和１９９０年２月２２－２６日期间在长江口北槽航区域现场投放和观测，集沙杯由有机玻璃制成，内径为５ｃｍ，杯高２１ｃｍ。对在小风情形，小风转大风情形和寒潮大风情形下集沙杯捕获沙样的干重和沙样的中值粒径垂直分布的特征分别作了描述，阱而为大风浪引起航槽游积及其底沙粗化提供了确凿证据。     

海水中磷氮不同形态的同时测定

采用过硫酸钾-硼酸-氢氧化钠混合试剂作为氧化剂,同时测定海水中总磷、氮和总溶解态磷、氮,从而建立了海水中磷、氮不同形态的分析流程及步骤。总磷、总溶解态磷浓度为0.35～1.09μmol/dm3时,相对标准偏差小于6.6%;总氮、总溶解态氮浓度为11.8～54.8μmol/dm3时,相对标准偏差小于5.6%。总磷、总溶解态磷和总氮、总溶解态氮的回收率分别为95.0%～106.0%和94.0%～106.0%。本文的分析方法可用于对近岸海水及河口水中磷、氮不同形态的同时测定。     

Empirical determination of geometric parameters for selective omission in a road network

Selective omission in a road network is a necessary operation for road network generalization. Most existing selective omission approaches involve one or two geometric parameters at a specific scale to determine which roads should be retained or eliminated. This study proposes an approach for determining the empirical threshold for such a parameter. The idea of the proposed approach is to first subdivide a large road network, and then to use appropriate threshold(s) obtained from one or several subdivisions to infer an appropriate threshold for the large one. A series of experiments was carried out to validate the proposed approach. Specifically, the road network data for New Zealand and Hong Kong at different scales (ranging from 1:50,000 to 1:250,000) were used as the experimental data, and subdivided according to different modes (i.e. administrative boundary data, a regular grid of different sizes, different update years, and different road network patterns). Not only geometric parameters, but also structural and hybrid parameters of existing selective omission approaches were involved in the testing. The experimental results show that although the most appropriate thresholds obtained from different subdivisions are not always the same, in most cases, the appropriate threshold ranges often overlap, especially for geometric parameters, and they also overlap with those obtained from the large road network data. This finding is consistent with the use of different subdivision modes, which verifies the effectiveness of the proposed approach. Several issues involving the use of the proposed approach are also addressed.     

偏硼酸锂熔矿-超声提取-电感耦合等离子体发射光谱法测定岩石水系沉积物土壤样品中硅铝铁等10种元素

采用偏硼酸锂熔矿分解样品,超声波振动提取,电感耦合等离子体发射光谱法同时测定同一份溶液中的硅、铝、铁、钙、镁、钾、钠、磷、锰、钛等组分。通过对岩石、水系沉积物和土壤国家一级标准物质测定验证,方法的准确度、精密度能够满足样品中各元素定量分析的要求。     

灰尘中主次量元素的X射线荧光光谱分析

采用粉末压片-X射线荧光光谱法对灰尘样品中P、Ti、V、Ni、Cu、Zn、Ga、Rb、Sr、Nb、Cs、Ba、La、Hf、Zr、Pb、Al2O3、CaO、Fe2O3、K2O、MgO、Na2O、SiO2等主次量组分进行测定。探讨了谱线校正,使用经验系数法和康普顿散射线作内标校正基体效应。用国家一级标准物质进行验证,测定值与标准值相符。     

阿根廷圣胡安激光测距系统的SLR数据质量分析

利用自行研制的激光定轨软件CASMORD分析阿根廷圣胡安激光测距系统的SLR数据质量.结果表明,阿根廷圣胡安激光测距系统性能良好,具有较小的系统偏差(距离偏差和时间偏差),系统偏差稳定,随时间的变化较小,有效观测圈数和数据观测量处于全球台站前列;经系统偏差修正后,该系统达到了亚厘米级观测水平,具有较高的观测精度,可以为卫星的精密定轨提供在我国本土无法观测的轨道弧段的资料,为我国科学研究和国家的特殊需要提供必须的宝贵资料.     

煤田测井中煤层的定性及定厚解释技术应用

选择使用观测钻孔内3种(含3种)以上有效的煤田测井物性参数,分析和对比所有曲线表现的异常特征,从中发现煤层与围岩的突出特性,达到对目的层的定性解释,而定厚解释是重点利用视电阻率和γ-γ曲线异常的典型特征值,确定煤层的深度、厚度和结构,有时还利用诸物性参数曲线异常的形态特征、标志层、对比方法,对个别煤层进行定位定论。     

Geodesy and relativity

Relativity, or gravitational physics, has widely entered geodetic modelling and parameter determination. This concerns, first of all, the fundamental reference systems used. The Barycentric Celestial Reference System (BCRS) has to be distinguished carefully from the Geocentric Celestial Reference System (GCRS), which is the basic theoretical system for geodetic modelling with a direct link to the International Terrestrial Reference System (ITRS), simply given by a rotation matrix. The relation to the International Celestial Reference System (ICRS) is discussed, as well as various properties and relevance of these systems. Then the representation of the gravitational field is discussed when relativity comes into play. Presently, the so-called post-Newtonian approximation to GRT (general relativity theory) including relativistic effects to lowest order is sufficient for practically all geodetic applications. At the present level of accuracy, space-geodetic techniques like VLBI (Very Long Baseline Interferometry), GPS (Global Positioning System) and SLR/LLR (Satellite/Lunar Laser Ranging) have to be modelled and analysed in the context of a post-Newtonian formalism. In fact, all reference and time frames involved, satellite and planetary orbits, signal propagation and the various observables (frequencies, pulse travel times, phase and travel-time differences) are treated within relativity. This paper reviews to what extent the space-geodetic techniques are affected by such a relativistic treatment and where—vice versa—relativistic parameters can be determined by the analysis of geodetic measurements. At the end, we give a brief outlook on how new or improved measurement techniques (e.g., optical clocks, Galileo) may further push relativistic parameter determination and allow for refined geodetic measurements.     

矿山环境地质问题综合评价客观权值确定方法探讨

笔者针对矿山环境地质问题综合评价权值的确定做了较深入的探讨。文中给出了以矿山地质环境调查数据库数据值客观确定评价指标权值的方法,对比介绍了专家问卷调查确定评价指标权值的方法,并对这两种方法进行了分析、对比,通过实例阐述了利用客观加权分值综合评价法评价矿山环境地质问题的适用性和可信性,试图为开展中国矿山环境地质问题综合评价及图件的编制奠定初步的理论基础。