当前对于火星进入、下降与着陆过程(entry,descent and landing,EDL)气动环境认知不足,任务风险高。在EDL系统上搭载传感仪器进行飞行数据测量,重建火星大气和气动热环境,并开展充分全面的地面验证是验证科学设计工具和降低未来火星EDL...当前对于火星进入、下降与着陆过程(entry,descent and landing,EDL)气动环境认知不足,任务风险高。在EDL系统上搭载传感仪器进行飞行数据测量,重建火星大气和气动热环境,并开展充分全面的地面验证是验证科学设计工具和降低未来火星EDL任务风险的有效途径,对任务成功与否至关重要。本文首先回顾了人类火星探测任务的发展历程,明确设置热防护传感系统的必要性;然后系统总结了美国两次火星着陆任务MSL、Mars 2020,欧洲ExoMars2016任务和中国天问一号任务所搭载的EDL热防护传感系统的体系构成,以及为满足任务要求,如何进行仪器选择与布局;归纳了4次任务飞行数据的重建方法、关键技术和结果结论;最后给出了EDL热防护传感系统总结的经验、面临的技术难题和未来发展建议。展开更多
在火星探测任务的进入飞行过程中,开展气动测量将获取大量宝贵的气动特性数据,一方面可以验证进入探测器气动外形,掌握其准确的气动特性,另一方面,可以积累详实的火星大气数据,为后续任务提高落点精度等飞行性能提供支持.本文针对火星...在火星探测任务的进入飞行过程中,开展气动测量将获取大量宝贵的气动特性数据,一方面可以验证进入探测器气动外形,掌握其准确的气动特性,另一方面,可以积累详实的火星大气数据,为后续任务提高落点精度等飞行性能提供支持.本文针对火星探测器进入飞行任务,基于弹道重建和嵌入式大气数据传感系统(flush air data system,FADS),提出火星探测器进入飞行过程中的气动测量方法.通过融合火星进入外测弹道信息,利用输出误差法实现攻角、侧滑角的高精度测量;基于嵌入式大气数据传感系统,利用最小二乘最优估计算法,建立了进入飞行动压的测量方法.仿真分析表明,气动测量方案精度高,进入动压测量精度优于1%,攻角和侧滑角测量精度相较于当前火星探测器进入气动测量而言,至少提升1个量级.研究结果将为火星探测等深空探测任务的进入飞行气动测量提供技术参考.展开更多
The literature suggests that protection of knowledge from the threat for opportunism is a primary mover for the choice of entry mode.However,the knowledge construct is oversimplified in the literature on entry mode.Th...The literature suggests that protection of knowledge from the threat for opportunism is a primary mover for the choice of entry mode.However,the knowledge construct is oversimplified in the literature on entry mode.The combination of different types of knowledge held by a firm reduces the risk of misappropriation and the threat of opportunism is often unimportant in entry mode decisions.Based on these discussions,a new conceptual knowledgebased model of entry mode choice is devoloped.In this model,the knowledge is classified into business knowledge and location knowledge,the strategies into exploitation and exploration.This model focuses on two main attributes of knowledge,namely,embedded ness and complementarity.It is suggested that embedded ness and complementarity of business knowledge and location knowledge affect the entry mode choice.The knowledge strategies moderate the relationships between the attributes of knowledge and entry mode.Transferring capacity is also introduced in this model.展开更多
文摘当前对于火星进入、下降与着陆过程(entry,descent and landing,EDL)气动环境认知不足,任务风险高。在EDL系统上搭载传感仪器进行飞行数据测量,重建火星大气和气动热环境,并开展充分全面的地面验证是验证科学设计工具和降低未来火星EDL任务风险的有效途径,对任务成功与否至关重要。本文首先回顾了人类火星探测任务的发展历程,明确设置热防护传感系统的必要性;然后系统总结了美国两次火星着陆任务MSL、Mars 2020,欧洲ExoMars2016任务和中国天问一号任务所搭载的EDL热防护传感系统的体系构成,以及为满足任务要求,如何进行仪器选择与布局;归纳了4次任务飞行数据的重建方法、关键技术和结果结论;最后给出了EDL热防护传感系统总结的经验、面临的技术难题和未来发展建议。
文摘在火星探测任务的进入飞行过程中,开展气动测量将获取大量宝贵的气动特性数据,一方面可以验证进入探测器气动外形,掌握其准确的气动特性,另一方面,可以积累详实的火星大气数据,为后续任务提高落点精度等飞行性能提供支持.本文针对火星探测器进入飞行任务,基于弹道重建和嵌入式大气数据传感系统(flush air data system,FADS),提出火星探测器进入飞行过程中的气动测量方法.通过融合火星进入外测弹道信息,利用输出误差法实现攻角、侧滑角的高精度测量;基于嵌入式大气数据传感系统,利用最小二乘最优估计算法,建立了进入飞行动压的测量方法.仿真分析表明,气动测量方案精度高,进入动压测量精度优于1%,攻角和侧滑角测量精度相较于当前火星探测器进入气动测量而言,至少提升1个量级.研究结果将为火星探测等深空探测任务的进入飞行气动测量提供技术参考.
文摘The literature suggests that protection of knowledge from the threat for opportunism is a primary mover for the choice of entry mode.However,the knowledge construct is oversimplified in the literature on entry mode.The combination of different types of knowledge held by a firm reduces the risk of misappropriation and the threat of opportunism is often unimportant in entry mode decisions.Based on these discussions,a new conceptual knowledgebased model of entry mode choice is devoloped.In this model,the knowledge is classified into business knowledge and location knowledge,the strategies into exploitation and exploration.This model focuses on two main attributes of knowledge,namely,embedded ness and complementarity.It is suggested that embedded ness and complementarity of business knowledge and location knowledge affect the entry mode choice.The knowledge strategies moderate the relationships between the attributes of knowledge and entry mode.Transferring capacity is also introduced in this model.
