GNSS地基集成测试与开发环境

GNSS地基集成测试与开发环境可测试和监测GPS,GLONASS,GALI-LEO等多种导航星座的空间信号,更重要的是测试和认证各种新型接收机和应用产品的性能和指标。同时为新的GNSS系统投入运行前进行必要的信号结构试验、接收机试验等。本文从集成测试与开发环境建立动机和目标入手,重点阐述了其运行模式、系统结构、测试区域选择标准,并进行了逼真度分析以及系统规划。以期对我国自主研发GNSS集成测试与开发环境做些探索性工作。     

卫星总体可靠性安全性设计审查

为了确保卫星及其产品不带问题出厂、不带隐患上天,进行系统、全面的卫星可靠性安全性设计专项审查,从卫星总体层面去把握卫星各系统和单机的安全性、可靠性,找出影响卫星安全性和可靠性的问题和薄弱环节,并及时采取有效措施加以改造,对于卫星研制是十分必要和有效的手段。文章基于如何立足卫星总体层面进行可靠性、安全性设计审查提出了一套具体的思路及方法。     

一种多波段组合的孤立噪声去除方法

首次提出了一种多波段组合的孤立噪声去除方法.文章在对图像进行中值滤波处理之前,先进行门限法的孤立噪声初步定位,设定孤立噪声为候选点;然后结合多波段图像数据对候选孤立噪声进行最终定位,只有当像元判断为真实的孤立噪声时,进行中值滤波处理;最后以中国一颗传输型卫星图像为例,检验了算法的有效性.     

航天器机构固体润滑球轴承磨损失效模型

根据赫兹接触理论和运动学基本原理,推导了固体润滑球轴承的接触应力和滑动速度公式。基于“航天器机构固体润滑球轴承的失效主要取决于固体润滑膜磨损”的分析结论,建立了固体润滑球轴承的磨损失效模型,并用已有的试验数据进行了初步验证。     

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。     

In-orbit operation and performance of the CubeSat Soft X-ray polarimeter PolarLight

PolarLight is a compact soft X-ray polarimeter onboard a CubeSat, which was launched into a low-Earth orbit on October 29, 2018. In March 2019, PolarLight started full operation, and since then, regular observations with the Crab nebula, Sco X-1, and background regions have been conducted. Here we report the operation, calibration, and performance of PolarLight in the orbit. Based on these, we discuss how one can run a low-cost, shared CubeSat for space astronomy, and how CubeSats can play a role in modern space astronomy for technical demonstration, science observations, and student training.     

Simulation of unsteady combustion in a LOX-GH2 fueled rocket engine

This paper presents results from an investigation of unsteady combustion inside a small-scale, multi-injector liquid rocket engine. A time-accurate approach in an axisymmetric geometry is employed to capture the unsteady flow features, as well as the unsteady heat transfer to the walls of the combustion chamber. Both thermally perfect gas (TPG) and real gas (RG) formulations are evaluated for this LOX-GH₂ system. The Peng–Robinson cubic equation of state (EoS) is used to account for real gas effects associated with the injection of oxygen. Realistic transport properties are computed but simplified chemistry is used in order to achieve a reasonable turnaround time. Results show the importance of the unsteady dynamics of the flow, especially the interaction between the different injectors. The RG EoS, despite a limited zone of influence, is shown to govern the overall chamber behavior. The sensitivity of the results to changes in the system parameters is studied and some general trends are discussed. Although several features of the simulations agree well with past experimental observations, prediction of heat flux using a simplified flux boundary condition is not completely satisfactory. Reasons for this discrepancy are discussed in the context of the current axisymmetric approach.     

RMI分布式对象技术的研究与应用

目前，基于Java RMI（Remote Method Invocate）的分布式对象技术在我国航空制造企业的大型分布式应用系统的开发整合中有着较为广泛的应用。在介绍RMI的体系结构、工作原理、互操作机制以及主流分布式对象技术的基础上，给出了RMI技术的具体实现方法和应用实例。     

微型涡流发生器控制超临界翼型边界层分离实验研究

在低速风洞中研究了微型涡流发生器对超临界翼型边界层分离的控制。根据超临界翼型边界层分离特性，提出了涡流发生器的流动机理。研究了梯形涡流发生器不同高度和弦向位置对边界层分离控制效果的影响。研究表明，微型涡流发生器对超临界翼型边界层分离的控制主要起减阻作用；适宜采用微型涡流发生器对超临界翼型边界层分离进行控制，其最佳位置应在分离线前2～5日涡流发生器高度之间。