Theoretical analysis of RAIM in the occurrence of simultaneous two-satellite faults

Most algorithms on receiver autonomous integrity monitoring (RAIM) are under the assumption of a single-satellite fault, because there is an extremely small probability that significant simultaneous multiple-satellite faults may occur. However, after the implementation of the Galileo system in a few years, there will be more satellites in view for the user to utilise together with GPS satellites, and a combination of them will bring better performance for RAIM. On the other hand, with the help of wide area augmentation system and the use of dual-frequency operation, pseudo-range errors will be reduced greatly. Thus, tighter alert limits are required for RAIM, and formerly `small' errors should not be neglected. All of those factors make it necessary to consider simultaneous multiple-satellite faults. A detailed theoretical analysis of RAIM under the condition of two-satellite faults for both vertical and horizontal directions is presented. The characteristic/max slopes for every pair of satellites are then deduced in order to calculate the tighter vertical/horizontal protection level for RAIM     

Fabrication of multi-walled carbon nanotube reinforced polyelectrolyte hollow nanofibers by electrospinning

Hybrid hollow multi-walled carbon nanotubes (MWCNTs)/polyelectrolytes (PE) nanofibers were prepared by a combination of the electrospinning method and layer-by-layer (LbL) technique. The mixed polystyrene (PS)/MWCNTs nanofibers were obtained by electrospinning method, which were employed as templates to self-assembly multilayered polyelectrolytes by LbL technique. Hollow MWCNTs/PE nanofibers were obtained by selectively removed part of the template: PS, which is confirmed by Raman spectra, transmission electron microscopy (TEM) and scanning electron microscopy (SEM).     

电荷离散化时介观电子谐振腔的量子线路方程与量子电流

基于电荷的离散性,运用最小平移算符的性质,研究介观电子谐振腔中量子电流的性质,给出量子Kirchhoff方程、量子电流关系式以及电流的量子涨落.结果表明,基于电荷量子化的事实,谐振腔中电荷具有量子振荡行为,量子电流关系及其量子涨落分别与电荷量子、Planck常数等有关,大小决定于体系的自感参量.     

螺栓角钢钢节点的三维非线性有限元分析

对螺栓角钢钢节点半刚性连接采用非线性有限元分析方法 ,对连接中的主要构件的顶部、底部、腹板角钢、高强螺栓、梁翼缘、柱翼缘和柱翼缘加劲肋进行三维非线性有限元精细模拟 ,针对有无柱加劲肋、有无腹板角钢等几种连接的情况进行比较分析 ,探讨了螺栓角钢半刚性连接的受力性能。     

以天下之利供天下之需

长期以来,国外信息安全公司在中国的发展,交织着两种矛盾的现象: 一方面,国外安全公司在国内信息安全市场上坐拥半壁河山的份额,早些时候在高端市场 上更是占据着统治地位,其技术水平也被认为具有领先的优势。 另一方面,国外安全公司在国内的业务又时常被国内一些企业或机构所责难,认为它有碍 国家安全而要求加以限制或者规避。     

Towards real-time business intelligence

Analysing data to predict market trends of products and services and to improve performances of enterprise business systems has always been part of running a competitive business. But it is becoming essential nowadays that not only is the analysis done on real-time data, but also actions in response to analysis results can be performed in real time and instantaneously change parameters of business processes. This paper discusses issues and problems of current business intelligence systems, and then outlines our vision of future real-time business intelligence. We present a list of emerging technologies which could contribute to the realisation of real-time business intelligence and some examples of applying them to improve BT’s systems and services.     

阿拉丁重构在华业务

重新认识中国市场时隔1个月以后,阿拉丁知识系统有限公司创始人、总裁、首席执行官Yanki Margalit携带几位高级助手再次踏上了中国的土地,Yanki Margalit一行2005年6月初在北京嘉里中心举办酒会,面对到会的国内诸位嘉宾和媒体记者,Yanki Margalit 筹躇满志地宣称,阿拉丁将总结以往的经验,以新的姿态重构在华业务。     

Preparation of BaMgAl10O17∶Eu2+ and Its Phase Behavior in Microemulsion System

BaMgAl10O17∶Eu2 (BAM) was prepared in the microemulsion system and its phase behavior was studied. There exists a small region in the reverse microemulsion system where the dispersed particles are of spherical form. In this way, BAM blue phosphor with good dispersion can be synthesized. The microemulsion phase diagrams of the pseudo-ternary system (Triton X-100/cosurfactant-oil-BAM brine) were first established intuitively by the dilution method. The microstructure of microemulsions was determined through eyeballing, conductance technique, and polar optical microscopy. Its phase behavior is affected by various factors, such as temperature (room temperature, 30, 40 ℃), oil, surfactants, and cosurfactants in microemulsions. According to the phase diagrams, the microemulsion system of Triton X-100/1-hexanol-hexane-BAM brine was chosen to prepare the precursor. The BAM phosphor can be obtained via sintering the precursor at a comparatively low temperature. The phosphors were characterized by XRD and vacuum ultraviolet (VUV) spectra.