排序方式: 共有102条查询结果,搜索用时 698 毫秒
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空间站主动热控系统的作用是提供和保持航天员、仪器设备和结构部件所要求的温度、湿度和风速等热环境。本文以空间载荷机柜为热控系统的基本单元,建立了以单相流体循环回路为基础、采用液冷结合风冷的冷却方式的载荷机柜数学模型;介绍了模糊增量控制算法的工作原理;提出了采用模糊增量控制算法,以液冷支路进出口温差和风冷支路冷却量占总冷却量的比值为控制目标的反馈控制策略。同时文章采用数值模拟方法研究了控制系统的动态响应效果。仿真结果显示,模糊增量控制算法具有响应迅速、超调量小、无静态误差的特点,控制策略满足有效性、稳定性和高精确度的要求。 相似文献
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D. Koschny V. Dhiri K. Wirth J. Zender R. Solaz R. Hoofs R. Laureijs T.-M Ho B. Davidsson G. Schwehm 《Space Science Reviews》2007,128(1-4):167-188
ESA’s Rosetta mission was launched in March 2004 and is on its way to comet 67P/Churyumov-Gerasimenko, where it is scheduled
to arrive in summer 2014. It comprises a payload of 12 scientific instruments and a Lander. All instruments are provided by
Principal Investigators, which are responsible for their operations.
As for most ESA science missions, the ground segment of the mission consists of a Mission Operations Centre (MOC) and a Science
Operations Centre (SOC). While the MOC is responsible for all spacecraft-related aspects and the final uplink of all command
timelines to the spacecraft, the scientific operations of the instruments and the collection of the data and ingestion into
the Planetary Science Archive are coordinated by the SOC. This paper focuses on the tasks of the SOC and in particular on
the methodology and constraints to convert the scientific goals of the Rosetta mission to operational timelines. 相似文献
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在简要论述微波遥感定标技术工作特点的基础上,着重分析星载有源微波遥感定标技术基本原理和关键技术,比较了各种定标方法特点,提出了若干建议。 相似文献
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Giammarco Cialone Andrea Gianfermo Alessandra Di Cecco Silvia Mari Santi Cassisi Fabio Santoni Fabrizio Piergentili 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(1):800-811
Binary or multiple stellar systems, constituting almost a third of the content of the Milky Way, represent a high priority astronomical target due to their repercussions on the stellar dynamical and evolutionary parameters. Moreover the spectral study of such class of stars allows to better constrain the evolutionary theories of the Galactic stellar populations. By resolving the members of stellar systems through photometric observations we are able to perform more detailed measurements to infer their mass. In this paper we investigate the feasibility of a cubesat based mission including an optical payload to directly optically discriminate the members of a selected sample of binary systems. The scientific targets, consisting 11?M class dwarf stars binary systems, have been extracted from the already studied Riaz catalogue. These subset has been selected considering the star distance, the members angular separation, and the distance from the Galactic plane (due to limit the background and foreground contamination). The satellite concept is based on a 6 unit Cubesat embedding some commercial off the shelf components and an ad hoc designed optical payload occupying almost 4 units. The optical configuration has been chosen in order to fit the angular resolution requirements, as derived from the target characteristics. Moreover, according to the optical analysis and the computed field of view some requirements on the attitude control system have been inferred and fulfilled by the component selection. The paper is organized as in the following: a brief scientific introduction is made; consequently the project is described with particular attention to the optical design and the standard sub-systems; finally the conclusions are drawn and the future perspectives are investigated. 相似文献
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空中发射可以明显提高火箭有效载荷,减少火箭发射场地的数量和高额的维护经费,缩短发射周期。本文研究了空中发射初始状态对运载火箭有效载荷的影响,通过飞行轨道的模型简化,首先建立了火箭飞行的数学模型,然后定量地分析了发射高度和发射速度对火箭入轨后有效载荷的影响。研究结果表明:若提高发射高度和发射速度,可以明显增加有效载荷,且基本发射高度、发射速度分别与有效载荷表现为线性关系。相对地面发射来说,如果初始高度达到30千米,有效载荷提升到1.63倍;如果初始高度达到30千米,初始速度达到1000米每秒(约3马赫),有效载荷将是传统地面发射的5.43倍。单纯从初始高度和速度的因素看,初始发射速度对有效载荷提升的影响更显著,故在考虑经济性情况下设计发射平台时应更加注重发射速度的提高。 相似文献
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将某类海上自动作业系统简化为带移动负载的浮筒系统,其中负载简化为外径为180mm、约50kg重的柱型体,浮筒为外径533mm的圆筒;初步设计了浮筒系统的主参数。在此基础上,采用频域数值模拟计算,获得了浮筒自由状态下的固有周期和运动响应传递函数(RAO);再采用时域模拟方法,预报了3级海况下(JONSWAP谱)浮筒系统整体的运动响应特性,给出了运动响应幅值、最小干舷高度等特性参数,可为相关装备设计提供技术参考和借鉴。 相似文献
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针对分离式卫星载荷模块(PM)受到扰动时可能与服务模块(SM)发生碰撞的问题,综合音圈电机反电动势(back-EMF)和柔性线缆动力学的效应,基于牛顿欧拉法建立了分离式卫星(DFP)载荷模块动力学模型。基于Hertz接触理论,推导了分离式卫星碰撞过程中连续接触力模型,并分析了碰撞过程中产生的接触力对载荷模块指向精度和指向稳定度的影响。数值仿真结果表明,碰撞使得载荷模块指向精度和指向稳定度下降5个数量级,碰撞后载荷模块可再次恢复到超静超稳工作状态,恢复时间超过1400 s。本文建立的碰撞模型对研究分离式卫星碰撞规避和碰撞控制具有重要意义。 相似文献