Problems in the calibration of an acoustic device for the observation of bedload transport

Developments in theoretical and empirical modelling of bedload transport processes are hindered by the lack of an adequate data base for testing or establishing the models. Conventional methods of measuring bedload transport rates fail to provide the necessary continuous or frequent record of variations at a single section. Acoustic techniques have the potential to overcome this deficiency, but their application has been very limited. Some of the problems of calibrating an acoustic device in the field and in a laboratory flume are discussed, and a possible circuit design described which might minimize calibration difficulties by automatically subtracting the noise generated by flow turbulence.     

一种大文件多版本遥感影像数据组织管理方法

近年来,遥感技术的飞速发展使得影像数据的使用也越来越广泛和深入,而影像分辨率的增加,使得数据量急剧增长,对数据的存储和管理提出了很高的要求。针对传统遥感影像数据组织存储的不足,本文提出了一种大文件金字塔数据存储结构,用来高效存储管理影像数据;同时针对多时相遥感影像数据,提出了基于版本机制的影像数据管理模式。实验表明这种方法具有更高的存储检索效率。     

X-ray Raman scattering for structural investigation of silica/silicate minerals

We have performed X-ray Raman scattering (XRS) measurements on the oxygen K and silicon L absorption edges of four silica minerals: α-quartz, α-cristobalite, coesite, and stishovite. We have also calculated the partial electron densities of states (DOSs) and compared these with the XRS spectra. This study demonstrates that the short-range structure around the atom of interest strongly influences the XRS spectral features. Importantly, the oxygen K-edge XRS spectra are found to reflect the p-orbital DOS while the silicon L-edge spectra reflect the s- and d-orbital DOSs, even when a product of a momentum transfer and a mean radius of a electron orbit (1s for oxygen and 2p for silicon), Qr, is close to or larger than unity. Building on this, calculations of the partial DOSs for other silica phases are presented, including ultra-high-pressure phases, which provide a good reference for further XRS study of silica and silicate minerals. XRS measurements should be performed on not only either of oxygen or silicon but also on many kinds of constituent elements to reveal the structural change of glasses/melts of silicates under extreme conditions.     

电网频率的快速,高分辨率测量方法与技术

介绍了快速、高分辨率测量电网频率的方法与技术 ,并在电力生产与调度中得到实际应用。这一方法与技术对于一般低频频率的测量具有普遍意义。     

南沙群岛电子地图及其多媒体模式研究

近十年来随着高新技术发展应运而生的电子地图,具有信息丰富、直观易读、更新方便、使用灵活等优点。本文对南沙群岛中多国领土之争的大片航行危险区与他国非法侵占地、且自然条件复杂与调研程度不断深入的地区,进行了制作电子地图的科学依据和实际意义的论述。同时指出电子地图多媒体在该海域应用的前景与作用。     

网络环境下城市公开版电子地图数据更新方法

针对目前数据更新的研究落后于数据生产的现状以及广大用户对城市公开版电子地图的现势性的迫切需要,在已有研究成果的基础上,提出了网络环境下城市公开版电子地图数据更新的方法,并分析了数据更新周期的决定因子及其方式和周期,最后用实例加以证明。     

基于百度地图的应急避难场所查询系统的设计与开发

为了将福建全省各地的应急避难场所以电子地图的形式展示在互联网上,采用百度地图API接口二次编程及JaveScript网页脚本技术,实现每个应急避难场所标注在百度地图平台上,并提供应急避难场所的分布、名称、地址、功能分布图和公交线路查询,建成一个优良的地图可视化服务系统。     

钟山风景区电子地图设计与实现

随着电子地图的不断发展,其在智慧旅游中扮演的角色越来越重要.钟山风景区电子地图主要将三个风景区融为一体,既突出单个景点的特色,又从空间上直观反映景区间的联系.制作便民的钟山风景区电子地图有利于引导南京旅游业的发展.     

基于GPS/GSM/GIS的海船监控调度系统的构建

GPS/GSM/GIS技术在交通监控调度管理和导航中的应用越来越广泛,市场前景十分广阔.文中从某船队的货运作业船舶监控调度系统的构建出发,分析了海船监控调度系统的工作原理和系统结构,进而探讨了基于GPS/GSM/GIS技术集成的海船监控调度系统的设计实现方案.