基于UAS模式的馆际互借与文献传递系统认证方式初探

本文通过分析高校数字图书馆馆际互借与文献传递系统用户身份认证方式的发展过程,重点阐述基于CALIS馆际互借系统的UAS联合认证方式.共享了本校图书馆使用UAS联合认证方式的一些体会.     

An Algorithm for Parameter Identification of UAS from Flight Data

The aim of the present work is to realize an identification algorithm especially devoted to UAS （unmanned aerial systems）. Because UAS employ low cost sensor, very high measurement noise has to be taken into account. Therefore, due to both modelling errors and atmospheric turbulence, noticeable system noise has also to be considered. To cope with both the measurement and system noise, the identification problem addressed in this work is solved by using the FEM （filter error method） approach. A nonlinear mathematical model of the subject aircraft longitudinal dynamics has been tuned up through semi-empirical methods, numerical simulations and ground tests. To take into account model nonlinearities, an EKF （extended Kalman filter） has been implemented to propagate the state. A procedure has been tuned up to determine either aircraft parameters or the process noise. It is noticeable that, because the system noise is treated as unknown parameter, it is possible to identify system affected by noticeable modelling errors. Therefore, the obtained values of process noise covariance matrix can be used to highlight system failure. The obtained results show that the algorithm requires a short computation time to determine aircraft parameter with noticeable precision by using low computation power. The present procedure could be employed to determine the system noise for various mechanical systems, since it is particularly devoted to systems which present dynamics that are difficult to model. Finally, the tuned up off-line EKF should be employed to on-line estimation of either state or unmeasurable inputs like atmospheric turbulence.     

中兴BRAS在三明IP城域网中的应用

三明IP城域网自2002年以来使用了中兴BRAS,在随后的扩容工程中,又继续扩增了中兴BRAS.本文介绍了中兴BRAS典型的业务配置、故障处理等方面的维护经验,希望能深入挖掘中兴BRAS的潜能,更好地服务于IP城域网.     

SIP协议在VoIP中的实现

会议初始化协议(SIP)是一种基于应用层地信令控制协议,由于具有简单、灵活和良好扩展性地体系结构,将其融入Internet数字语音通信技术中,建立基于SIP的VoIP网络,将会成为下一代VoIP技术的发展趋势之一。为此,介绍了一种基于SIP协议的VoIP网络实现模型,详尽阐述了SIP在VoIP网络中的实现原理,以及SIP对整个对话的控制过程。     

Comparison of Particle Size Distributions Measured Using Different Techniques

In this article, particle size distributions (PSDs) measured by different techniques, including image analysis (IA), laser diffraction (LD), ultrasonic attenuation spectroscopy (UAS), and focused-beam reflectance measurement (FBRM), are compared for spherical glass beads and nonspherical silica flakes. It is shown that particle shape strongly affects the results obtained by different techniques. For spheres, the PSDs obtained by IA, LD, and UAS agree well. There is no consistent result among different particle measurement techniques for nonspherical particles. The conversion between PSDs obtained by IA, LD, and UAS has been based on particle shape factors. Caution must be exercised when a measured chord length distribution (CLD) is used to indicate the PSD during a process because the CLD result obtained by FBRM is complex, depending not only on the PSD, but also on particle optical properties and shape.     

SIP协议在视频监控系统中的应用

在当前的视频监控市场中,不同监控系统采用的信令控制协议不统一,互联互通困难,无法满足网络化时代对大规模电信级视频监控、远程访问、集中管理的需要。于是设计者们将目光投向了通用的SIP协议与H.323协议。H.323由于其协议族过于复杂庞大,不如SIP简单灵活、分布式控制,故将SIP作为未来市场视频监控的主流协议已成为业界共识。中国电信集团也在其《中国电信家庭视频监控业务技术规范》中,推荐将SIP协议作为首选控制协议来实现。本文介绍了一整套基于SIP协议的视频监控系统应用解决方案,涵盖了系统的基本组成和各类信     

无人机遥感平台技术研究与应用

作为一种新型的遥感平台,UAS(无人飞行器系统)具有优于其它遥感平台的灵活性、实时性、移动性等特点,本文介绍了UAS的发展现状及其关键技术,提出了UAS遥感平台的分类方法,从技术、市场、法律制度、成本等多方面考察了UAS应用于民用遥感领域的可行性。理论和实践证明,UAS平台在遥感技术的发展中必将发挥重要的作用,成为主流的遥感平台之一。     

A survey of guidance,navigation, and control systems for autonomous multi-rotor small unmanned aerial systems

This survey paper presents a holistic perspective on the state-of-the-art in the design of guidance, navigation, and control systems for autonomous multi-rotor small unmanned aerial systems (sUAS). By citing more than 300 publications, this work recalls fundamental results that enabled the design of these systems, describes some of the latest advances, and compares the performance of several techniques. This paper also lists some techniques that, although already employed by different classes of mobile robots, have not been employed yet on sUAS, but may lead to satisfactory results. Furthermore, this publication highlights some limitations in the theoretical and technological solutions underlying existing guidance, navigation, and control systems for sUAS and places special emphasis on some of the most relevant gaps that hinder the integration of these three systems. In light of the surveyed results, this paper provides recommendations for macro-research areas that would improve the overall quality of autopilots for autonomous sUAS and would facilitate the transition of existing results from sUAS to larger autonomous aircraft for payload delivery and commercial transportation.     

超声法纳米颗粒悬浮液粒径测量中温度影响的实验研究

针对医药、化工领域高浓度纳米悬浮液颗粒粒径超声检测中温度影响,采用超声衰减谱法(UAS)对体积浓度30%的纳米铟锡金属氧化物(ITO)水性悬浮液在循环流速800 r/min,温度298～358 K时颗粒粒径分布进行实验。结果表明:温度升高,超声幅值A减小,超声衰减系数增大,颗粒中位径D50增大,颗粒系分布曲线整体朝大颗粒方向偏移,但是分布宽度保持稳定的趋势。同时,将室温(298K)测量结果与CPS离心沉降颗粒测量仪对比,结果较吻合。通过线性回归的方法修正温度对测量结果的影响,超声衰减法能够应用于358K的高温下高浓度纳米颗粒检测。     

SIP协议的消息过程

本文在介绍SIP协议的基础上，分析了SIP协议消息及几个典型过程，并阐述了协议的架构特点及对VoIP发展的影响。