冻结轨道及其应用

近来在对地观测卫星系统的设计中越来越多地采用冻结轨道,因为它能使卫星(作为一个质点)在不同时刻通过同一纬度时具有相同的运动特性,这就使得卫星在不同时刻经过同一地区所得到的遥感图片具有相同的几何特性。本文详细地讨论了冻结轨道条件、性状及其应用     

基于DDS的雷达多目标相参回波信号生成方法

介绍了一种基于DDS的雷达多目标相参回波信号生成方法。通过在特定时刻对DDS生成的信号进行补相,可以使单DDS同时生成多个目标的与被测雷达全相参的常规脉冲和线性调频回波信号。最后给出了仿真结果。     

飞行仿真转台基于干扰观测器的鲁棒跟踪控制

对三轴飞行仿真转台系统,提出一种基于干扰观测器的鲁棒数字跟踪控制器的设计综合方法.该控制器由前馈控制器、闭环控制器及摩擦补偿环节组成.前馈环节由零相差跟踪控制器ZPETC (Zero Phase Error Tracking Controller)及FIR滤波器构成,闭环由比例微分(PD)控制及干扰观测器构成,摩擦补偿采用基于库仑模型的固定补偿方法.实验结果表明,该方法能有效提高跟踪性能,并且对系统参数变化和力矩扰动具有很强的鲁棒性.     

新的大型空间环境模拟器热沉的研制

我国新研制的一台大型空间环境模拟器,热沉是该设备中的重要分系统之一。经过几年的努力,各项技术要求均已圆满完成,现已正式投入使用。文章介绍了热沉的材料选择、结构布置、壁板形式、支撑结构及主要设计计算结果等。     

轻型飞行模拟器座舱中飞行员头部运动范围的求解

在轻型模拟器中,为获得头盔伺服系统有效的预测范围以及实现对其六自由度并联机构的结构优化,需要明确飞行员在进行飞行操作时的头部运动范围。本文在对影响头部运动的身体部位及关节的分析基础上,建立人体躯干至头部的结构模型。根据串联机器人运动学正解方法计算头部运动范围。仿真结果表明,求解得到的头部运动范围是符合人体运动规律的。同...     

The Geostationary Earth Radiation Budget Edition 1 data processing algorithms

The Geostationary Earth Radiation Budget (GERB) instrument is the first to measure the earth radiation budget from a geostationary orbit. This allows a full sampling of the diurnal cycle of radiation and clouds – which is important for climate studies, as well as detailed process studies, e.g. the lifecycle of clouds or particular aerosol events such as desert storms. GERB data is now for the first time released as Edition 1 data for public scientific use. In this paper we summarise the algorithms used for the Edition 1 GERB data processing and the main validation results. Based on the comparison with the independent CERES instrument, the Edition 1 GERB accuracy is 5% for the reflected solar radiances and 2% for the emitted thermal radiances.     

面向机务维护模拟机知识表达方法的研究

通过分析模拟机知识的特点和训练等级要求,根据模拟机系统功能原理操作和排故过程,提出面向对象的框架规则知识表达法。介绍该表达法的设计思路,建立框架结构、规则树和堆栈转换模式。最后进行实例分析,结果表明该方法具有可行性,为模拟机开发人员提供有效的仿真依据。     

Learning in an immersive digital theater

The Houston Museum of Natural Science, in collaboration with Rice University has an outreach program taking portable digital theaters to schools and community sites for over five years and has conducted research on student learning in this immersive environment. By using an external independent evaluator, the effectiveness of NASA-funded Education and Public Outreach (EPO) projects can be assessed. This paper documents interactive techniques and learning strategies in full-dome digital theaters. The presentation is divided into Evaluation Strategies and Results and Interactivity Strategies and Results. All learners from grades 3–12 showed statistically significant short-term increase in knowledge of basic Earth science concepts after a single 22-min show. Improvements were more significant on items that were taught using more than one modality of instruction: hearing, seeing, discussion, and immersion. Thus immersive theater can be an effective as well as engaging teaching method for Earth and Space science concepts, particularly those that are intrinsically three-dimensional and thus most effectively taught in an immersive environment. The portable system allows taking the educational experience to rural and tribal sites where the underserved students could not afford the time or expense to travel to museums.     

太阳模拟器复杂构型卫星稳态 温度场的数值模拟

文章基于蒙特卡罗-区域分解法,建立太阳模拟器内复杂几何构型卫星稳态温度场数学模型;利用数值模拟求解卫星表面太阳辐照面积、红外和太阳辐射传递系数,得到不同辐照条件下卫星的温度分布;分析太阳辐照的非均匀性和不稳定性对温度分布的影响。计算结果表明:蒙特卡罗-区域分解法对于太阳模拟器模拟空间外热流的仿真研究是一种非常有效的方法;太阳辐照非均匀性对温度分布的影响大于不稳定性所产生的影响。     

大型太阳模拟器研制技术综述

文章简要介绍了国外典型的大型太阳模拟器及其技术指标,并对其研制过程中的相关技术问题进行了较为全面的总结,包括光源的选择及点燃方式、光学系统的选用与设计、光学系统的装校、太阳模拟器性能测量以及冷却等,为我国研制KM6太阳模拟器提供了技术借鉴与参考。文章最后讨论了KM6太阳模拟器的总体设计方案,提出拟采用中等功率的氙灯作为光源,并将氙灯的点燃方式从垂直点燃改成水平点燃,避免了由于平面反射镜的存在而导致15%的能量损失。