光抽运铯原子束频标的二级多普勒频移研究

结合光抽运铯束频标的具体结构,论证了用余弦傅里叶逆变换的方法推导原子速度分布的可行性;用该理论对实验系统测量的Ramsey花样进行了分析,得到铯束管中有效原子真实的速度分布,该速度分布与铯束管的具体结构对速度的要求相一致;通过速度分布精确计算了影响光抽运铯束频标准确度的重要因素——二级多普勒频移,其大小为-3．5×10-13。     

基于Cesium的铁路线路三维场景空间信息服务

随着我国铁路信息化建设的不断推进,三维GIS和网络GIS在铁路领域中的应用逐渐深化。本文针对铁路线路三维场景空间信息服务,提出了基于三维开源引擎Cesium的铁路线路三维场景构建及网络应用方法,对Cesium架构与网络服务、线路三维地理环境构建、铁路工务基础设施工程组件三维模型构建进行了研究。为将铁路线路空间地理环境信息与铁路基础设施模型集成在Cesium三维引擎中,对铁路基础设施正向设计下的BIM模型进行了轻量化研究,实现了基于Cesium的网络化、跨平台、分布式铁路线路三维空间信息三维场景漫游、数据共享与功能服务。     

铯原子喷泉频标的相对论频移

详细分析了铯原子喷泉频标的相对论频移机制,其中包括频标内部的二级多普勒频移和重力频移,以及与频标位置有关的重力领移。导出了频移的计算公式,估算了频移的大小并讨论了它们对铯原子喷泉频标准确度的影响。     

Alkali and halogen chemistry in volcanic gases on Io

We use chemical equilibrium calculations to model the speciation of alkalis and halogens in volcanic gases emitted on Io. The calculations cover wide temperature (500-2000 K) and pressure (10⁻⁶ to 10⁺¹ bars) ranges, which overlap the nominal conditions at Pele (T=1760 K, P=0.01 bars). About 230 compounds of 11 elements (O, S, Li, Na, K, Rb, Cs, F, Cl, Br, I) are considered. The elemental abundances for O, S, Na, K, and Cl are based upon observations. CI chondritic elemental abundances relative to sulfur are used for the other alkalis and halogens (as yet unobserved on Io). We predict the major alkali species in Pele-like volcanic gases and the percentage distribution of each alkali are LiCl (73%), LiF (27%); NaCl (81%), Na (16%), NaF (3%); KCl (91%), K (5%), KF (4%); RbCl (93%), Rb (4%), RbF (3%); CsCl (92%), CsF (6%), Cs (2%). Likewise the major halogen species and the percentage distribution of each halogen are NaF (88%), KF (10%), LiF (2%); NaCl (89%), KCl (11%); NaBr (89%), KBr (10%), Br (1%); NaI (61%), I (30%), KI (9%). We predict the major halogen condensates and their condensation temperatures at P=0.01 bar are NaF (1115 K), LiF (970 K); NaCl (1050 K), KCl (950 K); KBr (750 K), RbBr (730 K), CsBr (645 K); and solid I₂ (200 K). We also model disequilibrium chemistry of the alkalis and halogens in the volcanic plume. Based on this work and our prior modeling for Na, K, and Cl in a volcanic plume, we predict the major loss processes for the alkali halide gases are photolysis and/or condensation onto grains. Their estimated photochemical lifetimes range from a few minutes for alkali iodides to a few hours for alkali fluorides. Condensation is apparently the only loss process for elemental iodine. On the basis of elemental abundances and photochemical lifetimes, we recommend searching for gaseous KCl, NaF, LiF, LiCl, RbF, RbCl, CsF, and CsCl around volcanic vents during eruptions. Based on abundance considerations and observations of brown dwarfs we also recommend a search of Io's extended atmosphere and the Io plasma torus for neutral and ionized Li, Cs, Rb, and F.     

基于WebGL的三维智慧管网系统的设计与实现

随着城市面貌日新月异,地下管网的建设也在持续推进,作为城市的地下“神经网络”,全天24 h保障城市的正常运转和发展。本文以实现城市管网管理系统的高可用、无插件、智能化为目标,采用“地上地下一体”“二三维一体”的设计理念,研究基于WebGL的三维智慧管网系统的关键技术,实现了管线设施管理的信息数字化、空间化与图形化。     

Estimation of suspended sediment sources using 137Cs and 210Pbex in unmanaged Japanese cypress plantation watersheds in southern Japan

To analyse suspended sediment sources in unmanaged Japanese cypress plantation watersheds, field measurements and fingerprinting of the suspended sediment was conducted in the Shimanto River basin in southern Japan. For sediment fingerprinting, ¹³⁷Cs and ²¹⁰Pb_ex were detected by means of gamma‐ray spectrometry in the surface soil of the forest floor, stream bank and truck trail and mobilized sediment by interrill erosion. The ¹³⁷Cs and ²¹⁰Pb_ex activities associated with the forest floor materials were considerably higher than those of the stream bank and truck trail. The ¹³⁷Cs and ²¹⁰Pb_ex activities associated with the suspended sediment were found to vary with the sampling period. Evidently, the suspended sediment can comprise materials generated from the forest floor by interrill erosion and those from the truck trail and/or stream bank. The multivariate sediment‐mixing model using ¹³⁷Cs and ²¹⁰Pb_ex showed that the contribution of the forest floor varied periodically, ranging from 23–56% in the Hinoki 156 subwatershed and from 18–85% in the Hinoki 155 subwatershed. The difference in the average contribution of the forest floor between Hinoki 156 (46%) and Hinoki 155 (69%) may relate to the presence of truck trail networks in the watershed. The truck trail network can play roles of sediment source and pathway for sediment from forest floor to stream channel due to the concentrated overland flow on the truck trail during heavy rainfall events. These results indicate that the forest floor should be recognized as a major source of suspended sediment in unmanaged Japanese cypress plantation watersheds. Copyright © 2008 John Wiley & Sons, Ltd.     

基于Cesium的海洋环境要素三维可视化研究

基于海洋环境要素数据多源的特点,三维地球的可视化显示更有利于海洋复杂信息传递.Cesium是一款免费、拥有诸多API(application programming interface)的开源地图引擎,本文将二维可视化渲染效果较好的点方式可视化法、点图标映射法和流线法应用在Cesium三维地球引擎中,以NetCDF数据...     

Extraction of Cesium and Rubidium with 4-tert-butyl-2- (α-methylbenzyl) phenol from Salt Lake Brine

This work shows the extraction of cesium( Cs~+) and rubidium( Rb~+) from salt lake brine containing potassium( K~+) and magnesium( Mg~(2+)). The results show that 4-tert-butyl-2-( α-methylbenzyl) phenol( t-BAMBP) diluted in sulfonated kerosene( SK) has an excellent extraction effect. Infrared spectroscopic studies indicate that polymerize to form the dimer in the t-BAMBP when Cs~+or Rb~+were extracted. The effects of K~+,Mg~(2+),t-BAMBP concentration,the volume ratio of organic phase to aqueous phase( O/A) and the alkalinity( pH) of aqueous phase were investigated.The K~+and Mg~(2+)should be eliminated through precipitating before the extraction and separation of Cs~+and Rb~+. The optimum extraction conditions of the experimental brine were as follows: 0. 8 mol/L t-BAMBP diluted in SK,pH≥13,a phase ratio of 1: 1,and an extraction contact time of 2 min at room temperature. The optimal extraction yields of Cs~+and Rb~+were as high as 100% and 85. 8%,in addition,8. 76% of K~+was co-extracted. Further work would increase the extraction yield and selectivity of Rb~+and realize the efficient separation of Cs~+and Rb~+from brine.     

基于Cesium的三维模型可视化

对大规模三维模型的Web传输与可视化渲染进行了研究.基于Cesium JS框架搭建网页三维地形场景,实现了glTF和3D Tiles两种模型的三维可视化;对不同层级的模型加载进行了对比;并从文件结构、数据存储方式等方面对两种三维模型进行了解析.结果 表明,两种模型在网络传输和渲染方面具有很大优势,可在复杂的三维地理信息...