Periodic X-ray outbursts from A0535+26, 2S1145-619 and GX301-2

We report Ariel V(SSI) observations of three X-ray pulsars A0535+26, 2S1145-619 and GX301-2 (2S1223-624). These sources exhibit X-ray outbursts which appear, on the basis of observations extending over 5 years, to have recurrence periods of 110 days, 187.5 days and 41.4 days respectively. If these periods are orbital in origin, the observed X-ray modulation may be explained in terms of an appreciable orbital eccentricity giving rise to time variable accretion. (In the case of GX301-2 published pulse timing data already provide independent evidence for a 41.4 day orbital period and an eccentricity e 0.4). The optical counterparts are all early-type stars; A0535+26 and 2S1145-619 are identified with Be main sequence stars and GX301-2 with a B2 supergiant which also shows an emission line spectrum. The implications of the observations in relation to possible mass transfer mechanisms in such systems are discussed.     

In Memoriam,Gautam D. Badhwar (1940-2001)

Space Science Reviews -     

S. W. Bougher,D. M. Hunten,and R. J. Phillips (eds.) Venus II - Geology,Geophysics, Atmosphere,and Solar Wind Environment

Space Science Reviews -     

Nonlinear hαMissile Longitudinal Autopilot Design with θ- D Method

In this paper, a new nonlinear H_infin control technique, called thetas-D H_infin method, is employed to design a missile longitudinal autopilot. The thetas-D H_infin design has the same structure as that of linear H_infin, except that the two Riccati equations that are part of the solution process are state dependent. The thetas-D technique yields suboptimal solutions to nonlinear optimal control problems in the sense that it provides an approximate solution to the Hamilton-Jacobi-Bellman (HJB) equation. It is also shown that this method can be used to provide an approximate closed-form solution to the state dependent Riccati equation (SDRE) and consequently reduce the on-line computations associated with the nonlinear H_infin implementation. A missile longitudinal autopilot design demonstrates the capabilities of thetas-D method. This new nonlinear H_infin design also shows favorable results as compared with the linear H design based on the linearized model.     

国内要闻(2011年2月1日-28日)

2月9日,上海飞机制造有限公司庆祝第2000架份新一代波音737水平安定面实现交付。2月12日,民航局召开了今年第一次航空安全委员会会议,对民航局安委会成员进行了调整,民航局党组成员全部纳入了安委会,民航局局长李家祥担任新一届安委会主任。     

国内要闻(2010年12月1日-31日)

12月1日,以深圳为基地的东海公务机有限公司获颁运行合格证。12月2日,民航人事人才工作会议在北京召开。12月5日,具有中国自主知识产权的、由民航局主持的"十一五"国家863计划重大项目"新一代国家空中交通管理系统"在四川绵阳通过验收,同时国家科     

MONTHLY BRIEFS(May.1-31,2000)

May9ThecoordinatingmeetingofChineseIATAmemberairlineswasheldinUrumqi,with21representativesfromIATABeijingOffice,and12domesticaircarriersattending.ThecontentsofIATA"WingsfortheFuture"andBSPplanninginChinawereintroducedandsomeproblemsrequiringcoordinationwerediscussed.May9"AirCargoCommitmentService"including"appointedflighttransport"and"timelimiteddispatching"wasforwardedbyChinaSouthernAirlinesThe3rdInternationalAirTrafficControlExpo.washeldinBeijing.May9-11AnIATAdelegationcamet…     

E. Kontizas,M. Kontizas,D.H. Morgan,and G.P. Vettolani (eds.). Wide-Faceted Field Spectroscopy,Proceedings of the 2nd Conference of the Working Group of IAU Commission 9 on "Wide-Field Imaging".

Space Science Reviews -