The sun in the far infrared and sub-mm region

A review is given of the solar radiation between wavelengths of approx. 5 m. and 1 mm. After discussing the astrophysical background (Section 2), we review the brightness temperatures measured in the continuous spectrum in the disk center (Section 3), and compare them with model predictions. The observed limb darkening (or brightening) is described in Section 4, and the line spectrum in Section 5. In Section 6 considerations are given on the usefulness of infrared observations for the investigation of small structures on the Sun.     

喷嘴雾化特性模糊评判模型

利用模糊综合评判法构造喷嘴雾化模糊关系矩阵，建立了描述喷嘴雾化特性的模糊数学模型，利用该模型分别对不同工况下的空气雾化喷嘴，离心式喷嘴雾化特征进行了理论计算，通过聚类，对5种实验工况进行了分类，计算的分类情况与实验结果基本一致，对空气雾化喷嘴，离心式喷嘴不同实验工况的雾化效果进行了正确的评判。     

Rosina – Rosetta Orbiter Spectrometer for Ion and Neutral Analysis

The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) will answer important questions posed by the mission’s main objectives. After Giotto, this will be the first time the volatile part of a comet will be analyzed in situ. This is a very important investigation, as comets, in contrast to meteorites, have maintained most of the volatiles of the solar nebula. To accomplish the very demanding objectives through all the different phases of the comet’s activity, ROSINA has unprecedented capabilities including very wide mass range (1 to >300 amu), very high mass resolution (m/Δ m > 3000, i.e. the ability to resolve CO from N₂ and ¹³C from ¹²CH), very wide dynamic range and high sensitivity, as well as the ability to determine cometary gas velocities, and temperature. ROSINA consists of two mass spectrometers for neutrals and primary ions with complementary capabilities and a pressure sensor. To ensure that absolute gas densities can be determined, each mass spectrometer carries a reservoir of a calibrated gas mixture allowing in-flight calibration. Furthermore, identical flight-spares of all three sensors will serve for detailed analysis of all relevant parameters, in particular the sensitivities for complex organic molecules and their fragmentation patterns in our electron bombardment ion sources.     

粉末高温合金粘塑性试验评定与本构模型参数估计

 开展了粉末高温合金 FGH95 550℃、600℃和 650℃等 3种温度下控制应变率单向拉伸试验和 550℃下循环加载试验研究,结果表明 :600℃以下,快、慢应变率时,5%的试验应变范围内应力—应变曲线都一直上升,不存在应力饱和现象,热恢复效应不显著;但 650℃下慢应变率时则存在较明显的应力饱和现象,反映出在此条件下必须考虑蠕变效应。温度越高应变率对 FGH95的拉伸力学性能影响越明显,但总的说来是一种应变率不甚敏感的循环硬化材料。最后,在试验的基础上建立了 FGH95的 Bonder-Partom统一弹-粘塑性本构模型,理论与试验吻合较好,表明该模型能够模拟 FGH95的应力-应变关系曲线、应变率响应特性以及循环硬化特性,从而为 FGH95粉末高温合金构件的高温应力分析打下了基础。     

Book reviews

Space Science Reviews -     

共轴反转直升机传动系统构型现状

共轴刚性旋翼高速直升机由共轴反转的两幅旋翼实现悬停和爬升,由尾推进桨实现高速前飞,旋翼不需要倾转,相对倾转式旋翼机可靠性更高,具有较好的发展前景。共轴反转传动系统是共轴刚性旋翼高速直升机的关键传动部件。本文分析了共轴反转传动系统构型原理;针对共轴反转输出功能需求,将共轴反转传动系统分为以圆柱齿轮为基础、以锥齿轮为基础、以面齿轮为基础和以差动轮系为基础实现共轴反转输出的4类传动系统构型。分别论述了4类共轴反转传动系统构型的国内外发展现状、主要特点和型号应用情况,为不同需求共轴式直升机的传动系统构型选型设计提供参考。     

CFAR behavior of adaptive detectors: an experimental analysis

We conduct an experimental analysis for assessing the constant false alarm rate (CFAR) behavior of four coherent adaptive radar detectors in the presence of experimentally measured clutter data. To this end we exploit several data files containing both land, lake, and mixed land and sea clutter, collected by two radar systems (the MIT Lincoln Laboratory Phase-One radar and the McMaster IPIX radar) at different polarizations, range resolutions, and frequency bands. The results show that all the receivers, in the presence of real data, don't respect their nominal probability of false alarm (P/sub fa/), namely they exhibit a false alarm rate higher than the value preassigned at the design stage. Nevertheless one of them, the recursive persymmetric adaptive normalized matched filter (RP-ANMF) is very robust, in the sense that it presents an acceptable displacement from the nominal P/sub fa/, in correspondence of all the analyzed scenarios.     

Who is who in Algol-land ?- Part I -

We computed the evolution through case A mass transfer for 8 systems with mass of the primary equal to 3 and 5 M₀, mass ratios 0.7 and 0.9, and different periods. To this we added similar results from Packet (1988) for M_i = 9 M₀, q_i = 0.6, P_i = 1.62 d.During the mass transfer two competing mechanisms in the gainer decide on the evolution of the system: the rejuvenation of this star as the increasing convective core mixes fresh hydrogen into the inner regions, and the acceleration of nuclear burning, responding to the increasing mass.In all the cases the net result is a faster decrease of the central hydrogen content compared to the mass losing star. The secondary fills its own critical Roche lobe and reversed mass transfer starts.From our results and those of Nakamura and Nakamura (1984), we find that reversed mass transfer occurs after core hydrogen burning of the secondary (case A₁B₂) approximately for periods larger than 1 d (M_1i = 3 M₀) to 2 d (M_1i = 13.4 M₀). For smaller periods this happens before the gainer ends its core hydrogen burning (case A₁A₂).     

Sounding rocket experiment of bare electrodynamic tether system

An overview of a sounding rocket, S-520-25th, project on space tether technology experiment is presented. The project is prepared by an international research group consisting of Japanese, European, American, and Australian researchers. The sounding rocket will be assembled by the ISAS/JAXA and will be launched in the summer of 2009. The sounding rocket mission includes two engineering experiments and two scientific experiments. These experiments consist of the deployment of bare electrodynamic tape tether in space, a quick ignition test of hollow cathode system in space, the demonstration of bare electrodynamic tether system in space, and the test of the OML (orbital-motion-limit) current collection theory.