Experimental and numerical study of chaff cloud kinetic performance under impact of high speed airflow

To solve the kinetic and diffusion problem of surface-type infrared decoy, multi-chaff kinetic models are established and chaff cloud holistic kinetic performance are analyzed under the impact of high speed airflow in this work. Chaffs rotate rapidly during the motion under the impact of high speed airflow. The rotation speed is correlated with lift, position of pressure center and aerodynamic damping. Computational Fluid Dynamics (CFD) is used to compute the aerodynamic coefficients of chaff. It is found that there exists serious aerodynamic interference which mainly relates to the overlapping area and distance among chaffs during the diffusion of chaff cloud. The chaff wind tunnel test and rocket sled experiment are carried out to verify the credibility of the models in this work. Then, the variation of chaff cloud expectation and extremum are analyzed to achieve the holistic kinetic and diffusing performance of chaff cloud. Simulation results demonstrate that the chaffs diffuse rapidly under the impact of high speed airflow and chaff cloud can be formed rapidly within 0.5?s. The shape of the chaff cloud is similar to cone that forms a certain angle with the horizontal plane and most chaffs focus on the second half.     

空间拦截红外末制导中的状态估计

本文首先简要地介绍了基于两种规范型的非线性状态观测器的设计方法，然后用该法解决了空间拦截红外末制导中拦截器与目标相对距离的估计问题，仿真结果表明估计的效果良好。     

M导弹制导规则分析

通过分析实测的M导弹制导指令信号数据，给出了该导弹的比例导航系数及其他一些修正系数的变化规律，并根据弹上单片计算机在不同的输入口状态下和其输出口输出数据随时间变化的情况，分析了计算机程序的运行流程及其功能。     

The infrared space observatory (ISO)

The Infrared Space Observatory (ISO), a fully approved and funded project of the European Space Agency (ESA), is an astronomical satellite, which will operate at wavelengths from 2.5–240 m. ISO will provide astronomers with a unique facility of unprecedented sensitivity for a detailed exploration of the universe ranging from objects in the solar system right out to distant extragalactic sources. The satellite essentially consists of a large cryostat containing at launch over 2000 litres of superfluid helium to maintain the Ritchey-Chrétien telescope, the scientific instruments and the optical baffles at temperatures between 2 K and 8 K. The telescope has a 60-cm diameter primary mirror and is diffraction-limited at a wavelength of 5 m. A pointing accuracy of a few arc seconds is provided by a three-axis-stabilisation system consisting of reaction wheels, gyros and optical sensors. ISO's instrument complement consists of four instruments, namely: an imaging photo-polarimeter (2.5–240 m), a camera (2.5–17 m), a short wavelength spectrometer (3–45 m) and a long wavelength spectrometer (43–196 m). These instruments are being built by international consortia of scientific institutes and have been delivered to ESA for in-orbit operations. ISO will be launched in September 1995 by an Ariane 4 into an elliptical orbit (apogee 70000 km and perigee 1000 km) and will be operational for at least 18 months. In keeping with ISO's role as an observatory, the majority of its observing time is being made available to the general astronomical community via a Call for Observing Proposals.     

Olbers an interplanetary probe to study visible and infrared diffuse backgrounds

The visible extragalactic background (though as yet undetected) is insufficient to explain the abundance of heavy elements in galaxies: either there should be some diffuse extragalactic light in the near infrared (from 1 to 10 m) and/or in the far infrared (100 m) if dust has reprocessed the star light. We propose a new space mission to be dedicated to the search and mapping of primordial stellar light from the visible to the mid-infrared (20 m). In this spectrum range, detectors have reached such a sensitivity that the mission should aim at being (source) photon noise limited, and not any longer background photon noise limited. For that purpose, a small passively cooled telescope with large format CCDs and CIDs could be sent beyond the zodiacal dust cloud (which is absent beyond a solar distance of about 3 AU). In that case, the only remaining foregrounds before reaching the extragalactic background, is due to the Milky Way integrated emission from stars and the diffuse galactic light due to scattering and emission by interstellar dust, which are all unavoidable. Maps of the extragalactic light could be obtained at the arcminute resolution with high signal to noise ratio. This mission is the next logical step after IRAS, COBE and ISO for the study of extragalactic IR backgrounds. It has been proposed as a possible medium-sized mission for the post-horizon 2000 ESA program that could be a piggy back of a planetary mission.     

提高RSA安全性的几种方法

RSA是目前数字签名领域中应用最为广泛的算法,本文详细论述了RSA算法的数学原理和实现过程,针对其安全性方面的漏洞和缺陷进行分析,提出了提高RSA算法安全性的参数选择方案与避免攻击的解决办法,最后对RSA的发展趋势做出展望.     

我国航空发动机用几种涂层技术的差距及未来发展

论述了航空发动机隐身、抗冲蚀、防钛火涂层的技术现状.强调研究多元合金化及复合冲蚀涂层、阻燃涂层及阻燃性能测试技术,研究强吸波和低红外发射涂层、宽频带和多频谱隐身、雷达与红外隐身兼容涂层,以促进我国隐身战机的研制.     

空间大气成分探测傅立叶变换红外光谱仪

文章阐述了用于空间大气成分探测傅立叶变换红外光谱仪的国外发展状况，主要介绍了几种国外先进的高分辨率空间大气探测用傅立叶变换红外光谱仪的结构、应用范围和技术指标，比较了这几种设备的优缺点和技术特点。     

双锥—圆筒红外辐射源特性的蒙特卡罗解

本文考虑了红外辐射源腔内的镜反射成份,采用镜-漫混合反射模式,用蒙特卡罗法求定空腔的定向有效发射率。在通解的数学模型基础上,还针对500K双锥-圆筒热管空腔求得其典型解,分析了空腔辐射特性与锥角的关系。利用本文提供的方法也可计算其他腔形的辐射特性。     

小型星载红外相机的研制

随着现代航天技术的发展 ,传统卫星开始向质量轻、体积小、任务单一、成本低廉、研制周期短、风险小、能快速灵活发射的微小型卫星发展 ,相应的对有效载荷也提出了微小型化的要求。作为有效载荷的重要部分 ,红外相机的微小型化更是有效载荷小型化的重点和难点。文章对小型红外相机的发展方向进行了论述 ,对红外相机的各个组成部分的小型化发展作了详细的介绍。