FY-4气象卫星定位用导航星选取方法

给出了一种导航星的选取方法,该方法以J1991.25 Hipparcos星表为中心,联合Tycho-2星表、SAO星表及Pulkovo视向速度表,通过精密历元转换至J2000.0历元时刻,引入位置精度阈值,使得高精度的恒星作为导航星,为高精度的卫星姿态反演奠定了基础;引入辅助导航星,以提高星图识别率和识别速度;通过对星图识别失败的个例分析,剔除冗余星,以进一步提高星图识别效率。189颗辅助导航星遍及全天球,其中亮于3等星的恒星占34.4%,非常有利于提高星图识别率,且弥补了部分天区恒星稀疏的不足。参考星表的不精确将引起姿态输出的误差,这是无法避免的,通过精密历元转换计算FY-4观测历元时刻的导航星精确位置,与直接利用常用星表中提供的恒星位置相比,改善了参考星的输入误差,是提高姿态确定精度的手段之一。     

支持主动注册和实时服务质量监测的地理信息目录服务

提出了一种结合爬行搜索技术、动态监测技术和带地理信息服务质量描述的地理信息目录服务机制,并以网络地图服务为例实现了原型系统。实验证明,本文提出的目录服务机制不但解决了传统目录服务存在的问题,而且能较好地满足用户在操作性、体验度和检索结果满意度方面的要求。     

最大熵法所建议的非G—R关系及其后果

目前,常用最大熵法求地震年均发生率以及地震活动性参数b。但所得结果往往和直接基于G.R 关系的极大似然估计或最小二乘估计的结果有差别。对差别的解释多归结为地震目录的不完整,但我们认为差别的来源在于最大熵法所建议的是一种非古登堡—里克特关系,因而,差别是必然的,地震目录越完整,差别越明显;反之,如某一地震目录的差别甚微,那正是该目录不完整的充分条件。本文还讨论了最大熵法所建议的新型震级-频度关系与通常的 G-R 关系的异同和选用原则。     

A note on point process analysis of Chinese earthquake data

In the analysis of Chinese earthquake history byLee andBrillinger (1979), the autointensity function of the earthquake sequence is estimated, based on a parametric model for the catalog inclusion probabilities. We show that an estimate of the autointensity function with essentially the same features can be obtained by smoothing the data to yield a nonparametric estimate of the inclusion probabilities. In addition, however, we illustrate that a somewhat less smooth estimate would lead to an autointensity function with little structure. The shape of the estimated autointensity function is hence dependent on the assumed smoothness of the inclusion probabilities. This is an issue which cannot be resolved statistically.     

国土房产信息资源目录服务系统研究与实现

在国土资源和房产管理局的信息化过程中,缺乏一个有效的系统来管理、使用这些庞大而分散的国土资源,这就需要建立国土资源目录服务系统。本文探讨了国土信息资源目录系统的功能、元数据框架,并实现了深圳市国土资源与房产信息资源目录,此系统提高了查询资源的效率、实现了跨部门和跨应用系统的信息资源的共享。     

基于SMCS的多源空间数据集成应用

为解决多源空间数据特别是不同参考基准数据实时集成困难的问题,通过分析空间元数据间关系,定义并利用元数据知识来实现空间元数据的动态聚合和目录服务SMCS的构建。实验结果表明顾及空间关系的SMCS提高了对空间信息的动态获取、处理和发布的能力和效率,为网格环境下多源数据的高效集成应用服务提供技术支持。     

Aggregation-based information retrieval system for geospatial data catalogs

Geospatial data catalogs enable users to discover and access geographical information. Prevailing solutions are document oriented and fragment the spatial continuum of the geospatial data into independent and disconnected resources described through metadata. Due to this, the complete answer for a query may be scattered across multiple resources, making its discovery and access more difficult. This paper proposes an improved information retrieval process for geospatial data catalogs that aggregates the search results by identifying the implicit spatial/thematic relations between the metadata records of the resources. These aggregations are constructed in such a way that they match better the user query than each resource individually.     

澜沧江流域小湾、糯扎渡水库地震台网震级完备性初探

利用b值稳定性方法计算了云南省澜沧江流域上的小湾和糯扎渡水库台网地震目录的最小完整性震级MC,并对其实际监控能力进行了分析。结果表明,随着台网的建设,小湾水库台网的监控能力呈微弱下降,MC由一期台站运行时的ML1.6变为一、二期台站运行时的ML1.7,表明台网的运行情况影响了其监控能力;糯扎渡水库台网的监控能力有了显著的提高,MC由一期台站运行阶段的ML1.3变为一、二期台站合并运行后的ML0.8。     

A catalog of X-ray sources as observed by the TTM/COMIS telescope onboard the Mir-Kvant observatory in 1988–1998

A catalog of X-ray sources as observed by the TTM/COMIS telescope onboard the Mir-Kvant observatory is presented. Brief information about the 67 sources detected at a confidence level higher than 4σ between 1988 and 1998 is provided. X-ray properties and characteristic spectra of different types of sources are briefly described.     

Evaluation of earthquake parameters used in the Indonesian Tsunami Early Warning System

Twenty-two of a total of 30 earthquake events reported by the Indonesian Agency for Geophysics, Climatology and Meteorology during the time period 2007–2010 were falsely issued as tsunamigenic by the Indonesian Tsunami Early Warning System (Ina-TEWS). These 30 earthquakes were of different magnitudes and occurred in different locations. This study aimed to evaluate the performance of the Ina-TEWS using common earthquake parameters, including the earthquake magnitude, origin time, depth, and epicenter. In total, 298 datasets assessed by the Ina-TEWS and the global centroid moment tensor (CMT) method were assessed. The global CMT method is considered by almost all seismologists to be a reference for the determination of these parameters as they have been proved to be accurate. It was found that the earthquake magnitude, origin time, and depth provided by the Ina-TEWS were significantly different from those given in the global CMT catalog, whereas the latitude and longitude positions of the events provided by both tsunami assessment systems were coincident. The performance of the Ina-TEWS, particularly in terms of accuracy, remains questionable and needs to be improved.