Late Stages of Stellar Evolution

A large fraction of ISO observing time was used to study the late stages of stellar evolution. Many molecular and solid state features, including crystalline silicates and the rotational lines of water vapour, were detected for the first time in the spectra of (post-)Asymptotic Giant Branch (AGB) stars. Their analysis has greatly improved our knowledge of stellar atmospheres and circumstellar environments. A surprising number of objects, particularly young planetary nebulae with Wolf-Rayet (WR) central stars, were found to exhibit emission features in their ISO spectra that are characteristic of both oxygen-rich and carbon-rich dust species, while far-IR observations of the PDR around NGC 7027 led to the first detections of the rotational line spectra of CH and CH⁺. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands, and the United Kingdom), and with the participation of ISAS and NASA.     

质量矩导弹的神经网络及自适应非线性控制

本文对质量矩控制导弹的动力学方程简化和控制系统的设计进行了研究。详细阐述了所提出的控制方法，介绍了径向基单隐层神经网络进行误差补偿的算法原理，用Lyapunov理论证明了所采用方法的稳定性。在给出了质量矩导弹的六自由度动力学方程和简化后的方程后，用所提出的方法设计控制系统。通过仿真分析，得出了本文所提出的方法具有较好的误差补偿能力的结论。     

Astrophysics in 2006

The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the Universe) and others of which there are always many, like meteors and molecules, black holes and binaries.     

Ionospheric behavior of the F2 peak parameters foF2 and hmF2 at Hainan and comparisons with IRI model predictions

Monthly median values of foF2, hmF2 and M(3000)F2 parameters, with hourly time interval resolution for the diurnal variation, obtained with DPS-4 digisonde observations at Hainan (19.4°N, 109.0°E) are used to study the low latitude ionospheric variation behavior. The observational results are compared with the International Reference Ionospheric Model (IRI) predictions. The time period coverage of the data used for the present study is from March 2002 to February 2005. Our present study showed that: (1) In general, IRI predictions using CCIR and URSI coefficients follow well the diurnal and seasonal variation patterns of the experimental values of foF2. However, CCIR foF2 and URSI foF2 IRI predictions systematically underestimate the observed results during most time period of the day, with the percentage difference ΔfoF2 (%) values changing between about −5% and −25%, whereas for a few hours around pre-sunrise, the IRI predictions generally overestimate the observational ones with ΔfoF2 (%) sometimes reaching as large as ∼30%. The agreement between the IRI results and the observational ones is better for the year 2002 than for the other years. The best agreement between the IRI results and the observational ones is obtained in summer when using URSI coefficients, with the seasonal average values of ΔfoF2 (%) being within the limits of ±10%. (2) In general, the IRI predicted hmF2 values using CCIR M(3000)F2 option shows a poor agreement with the observational results. However, when using the measured M(3000)F2 as input, the diurnal variation pattern of hmF2 given by IRI2001 has a much better agreement with the observational one with the detailed fine structures including the pre-sunrise and post-sunset peaks reproduced reasonably well. The agreement between the IRI predicted hmF2 values using CCIR M(30,000)F2 option and the observational ones is worst for the afternoon to post-midnight hours for the high solar activity year 2002. During daytime hours the agreement between the hmF2 values obtained with CCIR M(30,000)F2 option and the observational ones is best for summer season. The discrepancy between the observational hmF2 and that obtained with CCIR M(30,000)F2 option stem from the CCIR M(3000)F2 model, which does not produce the small scale structures observed in the measured M(3000)F2.     

Modelling of Ejecta as a Space Debris Source

When a micro-debris or a micrometeoroid impacts a spacecraft surface, a large number of secondary particles, called ejecta, are produced. These particles can contribute to a modification of the debris environment: either locally by the occurrence of secondary impacts on the components of complex and large space structures, or at great distance by the formation of a population of small orbital debris. This paper describes firstly, the ejecta overall production, and secondly, the lifetime and the orbital evolution of the particles. Finally the repartition of ejecta in LEO is computed. Some results describing the population as a function of size and altitude are presented.     

离箱扰动和折叠翼展开数学模型研究

根据箱式发射导轨与导弹，导弹与折叠翼的约束特点，应用动力学普遍定理和解除约束原理，创建了离箱扰动运动数学模型和拆卸叠翼展开过程计算数学模型，并将计算结果与飞行试验结果作了比较。     

Appearance of neutron stars in the state of subsonic propeller

The state of subsonic propeller is intermediate between the states of supersonic propeller and accretor in the evolutionary tracks of magnetized compact stars. The rotational rate of a star at this stage decelerates due to the interaction between its magnetosphere and the surrounding hot, quasi-static plasma envelope. The magnetospheric radius is smaller than the corotation radius and the boundary of the magnetosphere is stable with respect to interchange instabilities. The rate of the mass flux from the inner radius of the envelope to the stellar surface is limited by the rate of plasma diffusion into the magnetic field of the star. As a result, the subsonic propeller would appear as a low-luminosity accretion-powered pulsar with a soft X-ray spectrum.     

利用偏馈振子调整测控雷达跟踪通道相移技术研究

提出一种调整雷达跟踪通道相移的方法 ,即在雷达天线主面上配置偏馈振子 ,利用偏馈振子做为校准源调整雷达跟踪和 /差通道间的相移 ,并对该方法的可行性、可靠性及稳定性进行了实验研究。     

统一S波段测控信道调制指数设计方程

考虑了测距音提取滤波器以及返回噪声对统一Ｓ波段卫星测控信道的影响，采用图解和数学分析两种方法详细分析了已调载波的功率效率。在此基础上，分别推导出在有、无测距音提取滤波器两种情况下，调制指数的设计方程     

对转桨推进型鱼雷有动力影响研究

为使国内具备鱼雷有动力风洞试验能力 ,通过设备研制和对转桨推进型鱼雷性能研究试验表明 :一是动力对姿态导数影响达 40 % ,效率导数一般下降 1 0 %～ 1 5 % ,设计单位应重视上述特性对鱼雷航行与机动特性的影响 ;二是对转桨对雷体稳定性作用值得高度重视 ,传统认为对转桨是鱼雷辅助稳定装置的设计思想应有所调整 ,尤其对机动性要求高的鱼雷。