Ariane in the world launch vehicle market

Roland Deschamps, Secretary General of Arianespace, discusses the evolution of the Ariane family of launchers and the creation of Arianespace to market and manage Ariane production and launch services. Tha launcher market is analysed and the advantages of Ariane compared to the US Shuttle are identified.     

VTOL Aircraft Control Output Tracking Sensitivity Design

A method is presented for reducing trajectory sensitivity and achieving robust asymptotic tracking for linear feedback systems when there are parameter perturbations and disturbance inputs. The controller consists of a servocompensator containing the modes of the reference signals and disturbance inputs, a stabilizing feedback loop, and a feedforward compensator. Application of the method to the design of a vertical takeoff and landing (VTOL) aircraft flight control system is discussed. The use of a precompensator allows performance maneuvers such that the aircraft tracks desired trajectories and the feedforward and feedback signals aid in reducing the trajectory sensitivity to variations of parameters due to change in airspeed and to wind gust. Simulation results are presented to show the robust tracking, disturbance rejection, and sensitivity reduction capabilities of the flight control system.     

徐朝梁 中国著名直升机总设计师

在此次珠海航展上,大型民用直升机AC313的精彩表演吸引了观众热切的目光,作为总设计师,您眼中的AC313是怎样的定位?徐朝梁:AC313是借鉴原有型号平台的成功设计经验、采用成熟的先进技术、按照国际最新的适航标准、采用与国际接轨的适航审定程序自主研发的全新民用直升机,是目前国内最大吨位的直升机。     

Cooperative Routing for Maximizing Network Performance of Wireless Networks

To greatly increase spectral efficiency and improve network performance in wireless networks,a novel cooperative routing algorithm,namely maximum throughput cooperative routing(MTCR) algorithm,is proposed.According to cooperative link model,throughput analysis is presented to evaluate performance improvement in the process of exploiting cooperative commu-nication from physical layer to higher layer.Taking the throughput improvement as performance metric,a cooperative relay se-lection scheme is developed.Finally,based on the route constructed by adaptive forwarding cluster routing(AFCR) algorithm,each node on the route selects the optimum cooperative node from all the potential cooperative nodes to construct the coopera-tive link with maximum throughput so that cooperative route with maximum network throughput from source to destination can be set up.Simulation results show that compared with the noncooperative routing algorithm and minimum power selection de-code-and-forward(MPSDF) routing algorithm,the proposed algorithm can obviously improve network throughput in the pres-ence of low transmission power,large number of nodes and high spectral efficiency.     

重彩之上海世博会

从世博会诞生至今,已有一个半世纪的时间。举办这样的盛会能给主办城市带来什么?最重要的是,为主办国和主办城市注入创新精神、创新活力,引发人们对发展观念、增长方式、科技进步、文化传承、制度建设等多方面的反思和变革;反映在具体     

“天然”与“环保” 爱尔兰国家馆的关键词

2008年10月21日,爱尔兰共和国政府与上海世博会事务协调局正式签署2010年上海世博会参展合同并公布展馆方案。至此,爱尔兰国家馆揭开了神秘的面纱。爱尔兰国家馆的设计极具"天然"和"环保"理念,注重于充分展现爱尔兰在城市化进程中对空间有效利用以及都市可持续发展的演变。展馆由5个长方体展示区组成,错落有致地分布于不同的层面,五个展示区由倾斜的过道连接,分别演绎爱尔兰根据文化艺术划分的国家和城市不同时代的发展轨迹和人文特色。     

上海,我的第二个家

在中国的六年让我特别钟爱一个城市——上海。在我看来,上海是我居住和工作过的城市中最有意思的。每天出现眼前,匆匆经过的那些华丽而古老的建筑是我喜欢上海的原因之一。上海在这方面是独一无二的,因为她是世界上拥有艺术设计风格建筑最多的城市,没有任何一个城市可以与她媲美。所以,当你踱步在外滩边或徜徉在那些狭窄的弄堂里时,你会感受到在其他任何一个地方都不能有的特别体验。并且,由于我非常喜欢摄影,这种体验对于我来讲就更为珍贵了。