红外多光谱扫描仪主体设计

文中简要介绍了中巴合作地球资源卫星(CBERS)红外多光谱扫描仪主体(简称扫描仪主体)的组成和工作原理。     

1989年3月大宇宙线暴事件的特征

本文分析了1989年3月一系列大耀斑等离子体抛射引起的宇宙线强度变化的特征.除对中子成分分析外,还对μ介子成分及其各向异性特征作了分析,讨论了宇宙线强度变化与太阳耀斑特性和地磁扰动之间的关系。分析发现,宇宙线的Forbush下降不仅与太阳耀斑的级别、持续时间,以及在日面上的位置有关,而且还与光学耀斑是否伴有强的X射线暴、是否有强的射电爆发,以及是否引起强的地磁暴紧密有关.各向异性分析表明,3月大事件的各向异性明显小于宁静时的各向异性,这可能是因为受到太阳活动强烈调制之后,宇宙线各向异性趋于减小的原因.     

Real time localization of gamma ray bursts with INTEGRAL

The INTEGRAL satellite has been successfully launched in October 2002 and has recently started its operational phase. The INTEGRAL burst alert system (IBAS) will distribute in real time the coordinates of the gamma ray bursts (GRBs) detected with INTEGRAL. After a brief introduction on the INTEGRAL instruments, we describe the main IBAS characteristics and report on the initial results. During the initial performance and verification phase of the INTEGRAL mission, which lasted about two months, two GRBs have been localized with accuracy of 2–4 arcmin. These observations have allowed us to validate the IBAS software, which is now expected to provide quick (few seconds delay) and precise (few arcmin) localization for 10–15 GRBs per year.     

Radiative and hybrid cooling of infrared space telescopes

The designs of cold space telescopes, cryogenic and radiatively cooled, are similar in most elements and both benefit from orbits distant from the Earth. In particular such orbits allow the anti-sunward side of radiatively-cooled spacecraft to be used to provide large cooling radiators for the individual radiation shields. Designs incorporating these features have predictedT _tel near 20 K. The attainability of such temperatures is supported by limited practical experience (IRAS, COBE). Supplementary cooling systems (cryogens, mechanical coolers) can be advantageously combined with radiative cooling in hybrid designs to provide robustness against deterioration and yet lower temperatures for detectors, instruments, and even the whole telescope. The possibility of such major additional gains is illustrated by the Very Cold Telescope option under study forEdison, which should offerT _tel5 K for a little extra mechanical cooling capacity.     

直升机红外抑制器两种进气方式下的实验研究

利用地面模拟试验件通过实验比较分析了两种进气方式对红外抑制器性能的影响。为了模拟直升机前飞和悬停两种状态,在模型上端开口,分别引入旋翼下洗气流和前端进气,对比分析了这两种状态下模型壁面温度和红外辐射强度的大小。结果表明:引入速度为18 m/s的旋翼下洗气流使得模型壁面内外两侧均受到冷却气膜的保护,从而使壁面温度降低了36%;同时再引入流量为0.2 kg/s的前端进气,可使红外抑制器模型在3~5μm和8~14μm的红外辐射强度分别降低为原来的11%和28%。     

An improved approach for rainfall estimation over Indian summer monsoon region using Kalpana-1 data

In this paper, an improved Kalpana-1 infrared (IR) based rainfall estimation algorithm, specific to Indian summer monsoon region is presented. This algorithm comprises of two parts: (i) development of Kalpana-1 IR based rainfall estimation algorithm with improvement for orographic warm rain underestimation generally suffered by IR based rainfall estimation methods and (ii) cooling index to take care of the growth and decay of clouds and thereby improving the precipitation estimation.     

涡扇发动机排气系统红外特征

采用反向蒙特卡罗法(Reverse Monte-carlo,简称RMC)结合窄带模型计算了模型涡扇发动机(不带加力)排气系统的红外辐射强度。考虑了金属壁面的发射和反射以及燃气中CO2,CO和H2O等组分的吸收、发射和透射,组分的吸收系数由NASA SP3080数据库获得,并对判断射线归宿的过程进行了改进,开发了计算程序。实验测量了模型涡扇发动机排气系统的中波红外光谱辐射强度及其空间辐射强度分布。结果表明:计算得到的3～5μm波段内的光谱辐射强度以及空间辐射强度分布与实验值吻合较好,最大误差为10%左右,本文的计算方法能比较准确地反映涡扇发动机排气系统在非加力状态下的中波红外辐射特征。     

管中激光加速器的推力形成过程

管中激光加速器是一种新型的激光推力器,弹射体在管道中被加速。利用光线追踪法,根据光线在网格中的传播路径信息,运用辐射输运方程,得到流场的能量源项;数值求解含能量源项的流体控制方程,对管道中等离子体流场激波的形成和演化过程进行了研究。模型能够模拟空气光学击穿、空气对激光能量的吸收、等离子体对激光的屏蔽作用和推力形成过程,通过计算得到冲量耦合系数为3.61×10-4N/MW,等离子体内能转化为流场动能的比例约为9%。     

喷气动力装置的红外辐射源及其抑制

本文分析喷气动力装置的红外辐射源,并讨论抑制红外辐射的技术途径.喷气动力装置的红外辐射来源于燃烧引起的高温,并可区分为两大类:固体表面的辐射和热喷流的辐射.一般而言,抑制红外辐射可从以下三个方面着手:(1)用冷却或绝热的方法降低辐射表面的温度,或通过蔽挡阻止红外辐射的传播;(2)加速喷气流与周围空气的混合,使喷流温度快速降低;(3)降低燃烧产物中辐射成分的浓度.     

蛇形进气道的雷达截面分析

 本文采用复射线技术的原理和方法,通过场的高斯波束拟合,使这种理论能够用于进气道之类的大口径凹形腔体的雷达截面(RCS)特性分析。本文以弯曲的蛇形进气道为例,进行了RCS特性分析计算,并将计算值与测试值比较。结果表明,这种方法是一种比较准确而又十分有效的RCS预估方法。