Planetary exploration by robotic aerovehicles

Planetary aerobots are a new type of telerobotic science platform that can fly and navigate in a dynamic 3-dimensional atmospheric environment, thus enabling the global in situ exploration of planetary atmospheres and surfaces. Aerobots are enabled by a new concept in planetary balloon altitude control, developed at JPL, which employs reversible-fluid changes to permit repeated excursions in altitude. The essential physics and thermodynamics ofreversible-fluid altitude control have been demonstrated in a series of altitude-control experiments conducted in the Earth's atmosphere, which are described. Aerobot altitude-control technology will be important in the exploration of seven planets and satellites in our solar system. Three of these objects—Venus, Mars, and the Saturnian satellite Titan—have accessible solid surfaces and atmospheres dominated by the dense gases nitrogen or carbon dioxide. They will be explored with aerobots using helium or hydrogen as their primary means of buoyancy. The other four planets—Jupiter, Saturn, Uranus, and Neptune—have deep atmospheres that are predominantly hydrogen. It may be possible to explore these atmospheres with aerobots inflated with atmospheric gas that is then radiatively heated from the hotter gaseous depths below. To fulfill their potential, aerobots to explore the planets will need autonomous state estimators to guide their observations and provide information to the altitude-control systems. The techniques of acquiring these data remotely are outlined. Aerobots will also use on board altitude control and navigation systems to execute complex flight paths including descent to the surface and exploiting differential wind velocities to access different latitude belts. Approaches to control of these systems are examined. The application of aerobots to Venus exploration is explored in some detail: The most ambitious mission described, the Venus Flyer Robot (VFR), would have the capability to make repeated short excursions to the high-temperature surface environment of Venus to acquire data and then return to the Earth-like upper atmosphere to communicate and recool its electronic systems. Finally a Planetary Aerobot Testbed is discussed which will conduct Earth atmospheric flights to validate autonomous-state-estimator techniques and flight-path-control techniques needed for future planetary missions.     

A Macro Model of Frequently Changing Mobile Networks to Perform Flow and Access Control

The area covered by a mobile ad hoc network consists of obstacles that inhibit transmission and areas where communications can take place. Physical structures, such as buildings, that block transmission, or lakes, where forwarding nodes cannot be located, are permanent obstacles. Temporary obstacles are created as mobile nodes enter or leave an area. Our hypothesis is that the spaces between nearby obstacles are bottlenecks that inhibit the flows in the network. We partition the network into areas that are encompassed by obstacles and bottlenecks. All of the nodes in an area are treated as a single super node, and the bottlenecks between areas are the links between the super nodes. As individual nodes move, the flows and paths in the model change more slowly than the paths and flows between the individual nodes. We apply flow control algorithms to the model and perform admission control within a super node based on the flows that are assigned by the flow control algorithm. We apply the model to the Columbia University campus, and use max–min, fair bottleneck flow control to assign the flows. Our hypothesis is verified for this example.     

基于嵌入式移动浏览器的QtWebkit 2.1内核研究与开发

通过对多种支持HTML5技术内核的分析,选取了Webkit内核Qtwebkit2.1。在对其进行深入分析的基础上,着重研究了它对HTML5的支持。最后选取并裁剪了基于Qtwebkit2.1内核的浏览器QtWeb,实现对MeeGo平台的移植。经实验表明,该嵌入式移动浏览器能部分支持HTML5技术规范,为以后的进一步研究奠定了良好的基础。     

基于移动锚节点的无线传感器网络圆心定位

文章提出了一种利用无线传感器网络无线信号接收强度（RSSI）和移动锚节点轨迹来获得待定节点位置的算法。该算法在有多个可移动锚节点的情况下,定位将会更加高效。在定位阶段,通过RSSI测得锚节点到待定节点的距离,并利用三个以上移动锚节点的坐标（包括三个）来求解圆的方程,计算出待定节点的位置。     

A novel compact low-power direct conversion receiver for mobile UHF RFID reader

A novel direct conversion receiver with low cost and low power is implemented in a 0.18 μm 1P6M standard CMOS process for a Mobile UHF RFID reader.A highly linear active mixer with low flicker noise and low noise active load is proposed.An efficient and low cost on-chip DC offset voltage canceling scheme is adopted with a high-input-impedance four-input OPAMP to buffer the output of the DC offset canceller(DCOC) block.The receiver has a measured input 1 dB compression point of 2 dBm and a sensitivity of 72 dBm in the presence of the large leakage signal from the transmitter.Only occupying a silicon area of 2.5 mm 2 and consuming 21 mA from a 1.8 V supply,the receiver makes the mobile UHF RFID reader to communicate with a transponder in a distance of 1 m conveniently.     

人体步行规律与仿人机器人步态规划

从仿生学角度分析了人体的步行运动规律,提出了一种基于人体运动规律的仿人机器人步态参数设定方法.首先对人体步行运动数据进行捕捉并分析,得出人体各步态参数间的函数关系,以人体步行相似性作为评价指标,提出仿人机器人步态参数的设定方法.其次,通过分析人体在步行过程中的补偿支撑脚偏航力矩的基本原理,提出了基于双臂及腰关节协调运动的仿人机器人偏航力矩补偿算法,以提高仿人机器人行走的稳定性.最后通过仿真及实验验证了所提出的步态规划方法的正确性及有效性.     

基于SMS的移动电子商务安全问题与对策

文章首先介绍基于SMS的移动电子商务工作模式和安全需求,以此提出了移动电子商务系统的总体安全架构,然后分别从终端接入层、通信链路层、网关协议层、应用服务层四个层面分析了移动电子商务常见的安全问题,最后提出了以动态口令与"挑战"文本相结合的认证方式,以Hash算法实现签名,端到端的SMS移动电子商务安全技术方案。     

IP/MPLS技术在移动通信信息系统中的应用研究

中国移动集团四川省移动公司MDCN网络本着先进性、现实性和经济性统一的原则进行设计,网络具有高性能、高可靠性、扩展性、标准化和可管理性的特点,能灵活地根据需求提供不同的服务等级并保证服务质量。该网络将采用最先进的IP/MPLS技术和高速设备,为各类信息系统提供统一的综合业务网络平台。     

增值税发票抵扣联移动认证系统的研究

无线通信技术和无线通信终端设备的发展为增值税发票抵扣联移动认证系统的研发提供了技术支持。文章从企业的实际需求为设计出发点,选择Visual Studio2005之C#作为本系统开发环境,综合利用微软移动通信技术(Microsoft Windows Mobile)和汉字设别技术,研发了增值税发票抵扣联移动认证系统。该系统通过"取得增值税专用发票→文字识别→无线认证→认证结果接收"等流程实现了增值税发票抵扣联的移动认证。