一种超小型汽泡铷原子频标

为满足对小型化铷原子频标的需求,设计了一种超小型汽泡铷原子频率标准。介绍了该超小型汽泡铷原子频标的设计。通过全新设计的小型光谱灯和集成腔泡系统,配合优化设计的电路部分,成功地将整机体积减小至140 cm3,重量仅为250 g,稳态功耗7 W。测试结果表明其短期稳定度优于1.5×10-11/τ(1 s≤τ≤100 s)。     

工业建筑综合防雷及电子设备的电磁兼容研究

本文对雷电引起的过电压及电子设备的电磁兼容性问题进行了分析研究,提出了传统防雷的改进措施和提高建筑物内电子设备电磁兼容性的措施。     

北斗卫星导航系统和GPS兼容性评估(英文)

北斗卫星导航系统的信号体制与GPS近似且占用相同的频段,不可避免地带来兼容性问题。从理论上分析兼容性评估的重要参数:频谱分离系数、码跟踪谱灵敏度和等效载噪比衰减,阐述伪随机码码长、导航数据速率和码片速率对兼容性计算的影响,在综合考虑信号兼容评估的运算速度和准确性的基础上,提出改进的GNSS兼容性评估模型。以此兼容性评估模型对北斗卫星导航系统和GPS所有频段进行仿真,仿真分析中考虑北斗卫星导航系统和GPS的具体频率分配、信号体制、发射功率、发射带宽、卫星天线增益、仰角、多普勒偏移、信号在空间传播的衰耗以及接收机参数。通过仿真可以看出,当北斗卫星导航系统满星座运行时,GPS对北斗系统的干扰将大于北斗系统对GPS的干扰。     

Host specificity, nutrient and water dynamics of the mistletoe Viscum rotundifolium and its potential host species in the Kalahari of South Africa

The mechanisms underpinning local host specificity in mistletoes remain elusive. We determined the degree of host specificity in the mistletoe Viscum rotundifolium at Pniel Estates, near Kimberley, South Africa. We found that V. rotundifolium parasitises only Ehretia rigida and Ziziphus mucronata at this site. Both commonly parasitised host species were not the most abundant trees, were not the tallest trees, and did not have the highest water or nutrient content of trees in the area, although these factors are good predictors for mistletoe parasitism. Mistletoe seeds deposited on branches of E. rigida and Z. mucronata have a greater chance of attachment and subsequent survival, compared with those seeds deposited on co-occurring Acacia and other potential host species. The mistletoes had higher water potential than their host trees and by doing so they can passively maintain the flow of nutrients. In addition, the mistletoes had a N:Ca ratio >1, indicating active uptake from host phloem. Thus, this mistletoe species uses both passive and active uptake, which may be a selective advantage in a nutrient-poor environment or on a nutrient-deficient host species.     

GPS控制网起算点的兼容性分析方法研究

GPS平面控制网成果转换为地方坐标系或者其他国家坐标系,必须给定相应的约束条件进行约束平差,起算点的兼容性分析是其得出良好平差成果的前提条件。本文主要通过直观分析法、单位权方差假设检验法、尺度参数法阐述了起算点兼容性分析的理论基础,并通过实例论证三种兼容性分析法的可行性、一致性,对相关工程中起算点的兼容性分析具有一定的参考价值。     

Enhancing accessibility to web mapping systems with technology-aligned adaptive profiles

Web-based geographic information systems have advanced rapidly on the back of web-based technologies, increased bandwidths and access to Digital Earth imagery and functionality. However, these advances are causing its capabilities to slowly overtake those of end-users. Additionally, the introduction of non-desktop devices such as smartphones, tablets and netbooks is starting to undo progress made towards standardisation of web-based technology. Large variations in screen sizes, computational power, bandwidth, and operating environments are once again introducing the need to ensure software remains functional across different platforms, standards-compliant or not. These two issues highlight the need for a mechanism to tune content and capability to end-users and their environment, to prevent information and complexity overload in a field already troubled by poor usability, while promoting cross-platform compatibility. This paper proposes the use of adaptivity to accommodate for users from different backgrounds accessing web mapping systems in different technical environments. It describes adaptive profiles aligned to the finite number of states a system can adopt, rather than the limitless range of user or environment characteristics that cannot be adapted to. Each profile consists of a combination of adaptive states comprising functionality, information detail, or technical demands to optimise for individual users or technical environments.     

市级人大常委会信息查询系统

政府信息化是社会信息化的基础，在此介绍了一个政府上网系统的具体实现技术，系统采用了C／S方式，客户端用浏览器实现系统的各项功能，对数据库的访问通过IDS实现。     

岩石破坏后的注浆固结体的力学性能

在破裂岩石残余强度和变形性能研究的基础上,进一步开展其注浆固结体的力学性能试验研究。试验证实注浆固结后破裂岩块残余强度有不同程度的提高,同时发现其侧向变形和径向变形趋向协调,从而提高了破裂岩块的塑性变形性能,并在较大变形范围内保持稳定的承载能力。试验结果有助于解释围岩注浆加固控制巷道变形的机理。     

一种资源一号卫星影像的正射纠正方法

针对传统遥感软件处理影像数据正射纠正时控制点精度不高的问题,提出了一种快速、精确正射纠正的改进方案。该方法首先利用PCI、ArcGIS与ERDAS软件相兼容的特点,通过PCI影像处理软件对实验区阳原县高分辨率遥感卫星影像CBERDS-02C进行正射纠正,得出控制点精度残差结果;然后利用ArcGIS软件对纠正后影像进行精度改进;最后在ERDAS影像处理软件中选取同名点对影像纠正精度改进后效果进行验证。实验结果表明:通过对比分析精度改善前后控制点残差结果,在ArcGIS软件中对精度改进是切实可行的。     

微机通讯软件COMTQOL 1—2—3的开发和应用

COMTOOL1—2—3(全称为Communication TooL)是我们最近开发的用于PC—1500、AppleⅡ和IBM—PC的微机通讯系统。它既能使这三种微机的BASIC程序相互在另一个机器上运行,也能使PC—1500成为AppleⅡ及IBM—PC的智能终端,还能使PC—1500成为AppleⅡ及IBM—PG的数据收集器。在BASIC程序移植、现场数据收集后的处理以及有效使用大容量微机等方面,该系统会减少大量的重复性劳动和不必要的机时耗费,使微机的有效利用率大大提高。本文介绍了它的实现方法和应用实例。