可变编码调制在遥感卫星中的应用效能研究

随着遥感卫星观测数据量的日益增加，卫星数据传输能力已成为制约遥感卫星使用效能的瓶颈因素。为充分利用近地遥感卫星数据传输的链路资源，采用可变编码调制（VCM）技术，通过对星地数传信道条件的动态评估，在保证链路传输误码率和链路余量的前提下，自适应地进行当前信道条件下的最优编码调制方式切换，充分利用系统链路余量，提高卫星星地数据传输效能。利用该方法，对VCM数传链路效能进行仿真分析，与相同符号速率的固定编码调制（CCM）体制相比，VCM传输效能平均提升42.1%，可为遥感卫星的数传通道设计提供借鉴。     

KrF激光对高速飞片的驱动特性研究

利用诱导空间非相干技术平滑的KrF准分子（248nm）激光驱动带有烧蚀层的平面靶，研究激光空间均匀性对产生完整飞片的影响，结果表明激光不均匀性在2％以下，能够产生完整的高速飞片，且完整飞片能够维持20ns以上不破裂；当激光不均匀性达到5％，激光引入流体力学不稳定性种子应很强，冲击波在靶内输运过程中不稳定性不断发展增强，到靶背时强到足以使飞片解体甚至气化，不能产生完整的飞片。为了获得尽可能高的飞片速度，采用激光与烧蚀层参数不匹配方法，使冲击波对飞片作多次加速。利用功率密度为1012 W/cm2的KrF激光与含50μm Kapton烧蚀层的5μm铝飞片作用，得到速度约10km/s的高速飞片，与模拟结果吻合得很好。     

Empirical model of cosmic ray spectrum in energy interval 1 MeV–100 GeV during 11-year solar cycle

The galactic cosmic rays (GCR) are the main ionization source at altitude of ∼3–35 km in the atmosphere. For high latitude anomalous cosmic ray (ACR) component has also a significant influence on the atmospheric ionization. We propose an empirical model for differential spectra D(E) of galactic and anomalous cosmic rays in energy interval 1 MeV–100 GeV during solar cycle. In the model data are used which cover three solar cycles: 20, 22 and 23. The LEAP87, IMAX92, CAPRICE94, AMS98 and BESS experimental spectra for protons and alpha particles are fitted to the proposed empirical model. The modulated GCR differential spectra are compared with force-field approximation to the one-dimensional transport equation and with solutions of two-dimensional cosmic ray transport equation. For experimental spectra, the calculation of the model parameters is performed by Levenberg–Marquardt algorithm, applied to the special case of least squares. Algorithm that combines the rapid local convergence of Newton–Raphson method with globally convergent method for non-linear systems of equations is applied for theoretically obtained differential spectra. The described programmes are realized in algorithmic language C++. The proposed model gives practical possibility for investigation of experimental data from measurements of galactic cosmic rays and their anomalous component.     

末修火箭弹抛物线比例导引的特性

基于抛物线比例导引原理,详细分析了弹道修正所需求的脉冲数。结合抛物线比例导引特性,对规定落角进行了理论分析与仿真。结果表明,规定落角越大,脉冲需求数越小,对规定落角的敏感性越大,落点修正距离会越小。提出了确定规定落角的基本原则:弹道修正段前期,规定落角主要由目标点位置决定,可根据火箭结构特点和使用环境特性,采用非线性控制系统确定;弹道修正段末期,规定落角对落点影响较小,可结合战技指标中毁伤效能要求确定。     

Challenges to cosmic ray modeling: From beyond the solar wind termination shock

Voyager 1 crossed the solar wind termination shock on December 16, 2004 at a distance of 94 AU from the Sun, to become the first spacecraft to explore the termination shock region and to enter the heliosheath, the final heliospheric frontier. By the end of 2006, Voyager 1 will be at ∼101 AU, with Voyager 2 at ∼81 AU and still approaching the termination shock. Both spacecraft have been observing the modulation of galactic and anomalous cosmic rays since their launch in 1977. The recent observations close to or inside the heliosheath have provided several interesting ‘surprises’ with subsequent theoretical and modeling challenges. Examples are: what does the modulation of galactic cosmic rays amount to in this region?; how do the anomalous cosmic rays get accelerated and modulated?; why are there ‘breaks’ in the power-law slopes of the spectra of accelerated particles? Several numerical models have been applied to most of these topics over the years and comprehensive global predictions have been made the past decade, thought to be based on reasonable assumptions about the termination shock and the heliosheath. Examples of these predictions and assumptions are concisely discussed within the context of the main observed features of cosmic rays in the vicinity of the termination shock, ending with a discussion of some of the issues and challenges to cosmic ray modeling in particular.     

Influence of atmospheric turbulence on planetary transceiver laser ranging

In this paper we investigate the influence of atmospheric turbulence on the performance of the uplink of a planetary transceiver laser ranging system using a single photon detector. We numerically combine the influence of turbulence in the mean intensity profile variations, scintillation, beam-wander induced pointing errors and stochastic time-of-flight variations, using the Hufnagel–Valley turbulence profile to model the ground turbulence behavior. We map the intensity variations due to turbulence to variations in the probability distribution of the arrival time of the 1st photon in a laser pulse, which influences the range measurement error probability distribution. The turbulence models are applied to assess the influence on single-pass range accuracy and precision statistics, as well as the parameter estimation quality of a Phobos Laser Ranging (PLR) mission.     

太赫兹脉冲测量技术及其在计量领域的应用CSCD

本文对国内外太赫兹脉冲的产生和测量技术进行了综述,详细介绍了太赫兹脉冲产生与测量技术的原理和优缺点,以及太赫兹脉冲技术在宽带示波器、超快光电探测器、超快脉冲产生器等仪器设备计量中的应用。     

航天器C语言软件常见编程错误分析及检测方法研究

基于软件第三方评测发现的问题,梳理并详细分析了在航天器C语言软件中6种常见编程错误.针对其中的软件安全漏洞提出了使用代码分析技术的检测方法,针对编程语言使用错误提出了通过制定编程规则并使用代码分析方法进行检测的解决方法.采用上述方法可以有效检测出上述6种常见编程错误,并可以用于检测软件的其他严重错误.     

基于功率复用的椭圆球面波函数非正交调制方法

围绕如何降低基于椭圆球面波函数的非正交调制（PSWF-NPSM）系统误码率，降低信号检测复杂度，引入调制信号功率复用思想，提出基于功率复用的椭圆球面波函数非正交调制（PD-PSWF-NPSM）方法。该方法对载波信号按子波带进行功率分配，增加了调制信号最小欧式距离，降低了系统误码率；在接收端，提出基于检测统计量的串行干扰相消信号检测方法，依据不同支路信号间功率差异，对信号进行分离、检测。理论与仿真分析表明，该方法在不降低系统频带利用率、调制信号功率谱、峰均功率比特性前提下，能够有效提高系统误码性能，降低调制信号检测复杂度；与原非正交调制方法相比，当误比特率（BER）为10^-5时，所提方法系统误码性能提升约1.7 dB。     

同时纠检错时某些线性分组码的不可检错误概率

研究同时纠错和检错时，线性分组码的不可检错误概率，证明了二元完备码及其扩展码是最佳纠检错码，而某些ＢＣＨ码不是最佳纠检错码。