文章介绍了 NASA 在1993年提出的空间环境及效应(下称 SEE)计划,其目的是明确空间环境的定义,为设计、研制能适应严酷空间环境效应的航天器系统并使其正常运行提供技术支持。该计划包括认识空间环境、飞行试验和地面试验技术的优化、更...文章介绍了 NASA 在1993年提出的空间环境及效应(下称 SEE)计划,其目的是明确空间环境的定义,为设计、研制能适应严酷空间环境效应的航天器系统并使其正常运行提供技术支持。该计划包括认识空间环境、飞行试验和地面试验技术的优化、更新空间环境及其效应的预测模型、保存信息并将之纳入航天器的设计流程等方面。文章描述了 SEE 计划目前已取得的成就和未来的打算。展开更多
"Long time no see" is a very interesting English expression used as a greeting by people who have not seen each other for a while. The essay shows how Chinese people and native English speaker think about &q..."Long time no see" is a very interesting English expression used as a greeting by people who have not seen each other for a while. The essay shows how Chinese people and native English speaker think about "Long time no see". Meanwhile, it does research upon the historical appearances of the phrase.展开更多
The advantages of the geographical conditions,natural,and cultural environment of Zhuhai agri-tourism are introduced,and the related development countermeasure is put forward.
We present seeing measurements of the Guoshoujing Telescope （formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope- LAMOST） site at Xinglong station during the period from 2007 March 12 to Apr...We present seeing measurements of the Guoshoujing Telescope （formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope- LAMOST） site at Xinglong station during the period from 2007 March 12 to April 25. The measurements were carried out with the Differential Image Motion Monitor （DIMM）, and a total of 9259 data sets was obtained. The median seeing was measured to be 1.1″, with 25% being better than 0.8″and 75% better than 1.5″. The experiment shows that the DIMM exposure time has significant effects on the results of seeing measurements. An SBIG Polaris seeing monitor, which had been planned to be installed on the LAMOST site for long-term monitoring, was also employed during the DIMM observations. The results show that the SBIG seeing monitor is easily affected by gusty wind, resulting in larger seeing values. Considering the previous seeing measurements at Xinglong station over the last 15 yr, we conclude that an acceptable seeing condition at Xinglong station is around 1″-2″.展开更多
文摘文章介绍了 NASA 在1993年提出的空间环境及效应(下称 SEE)计划,其目的是明确空间环境的定义,为设计、研制能适应严酷空间环境效应的航天器系统并使其正常运行提供技术支持。该计划包括认识空间环境、飞行试验和地面试验技术的优化、更新空间环境及其效应的预测模型、保存信息并将之纳入航天器的设计流程等方面。文章描述了 SEE 计划目前已取得的成就和未来的打算。
文摘"Long time no see" is a very interesting English expression used as a greeting by people who have not seen each other for a while. The essay shows how Chinese people and native English speaker think about "Long time no see". Meanwhile, it does research upon the historical appearances of the phrase.
文摘The advantages of the geographical conditions,natural,and cultural environment of Zhuhai agri-tourism are introduced,and the related development countermeasure is put forward.
基金supported by the National Natural Science Foundation of China(Grant Nos.10903014 and10778709)supported by the Young Researcher Grant of National Astronomical Observatories,Chinese Academy of Sciences
文摘We present seeing measurements of the Guoshoujing Telescope （formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope- LAMOST） site at Xinglong station during the period from 2007 March 12 to April 25. The measurements were carried out with the Differential Image Motion Monitor （DIMM）, and a total of 9259 data sets was obtained. The median seeing was measured to be 1.1″, with 25% being better than 0.8″and 75% better than 1.5″. The experiment shows that the DIMM exposure time has significant effects on the results of seeing measurements. An SBIG Polaris seeing monitor, which had been planned to be installed on the LAMOST site for long-term monitoring, was also employed during the DIMM observations. The results show that the SBIG seeing monitor is easily affected by gusty wind, resulting in larger seeing values. Considering the previous seeing measurements at Xinglong station over the last 15 yr, we conclude that an acceptable seeing condition at Xinglong station is around 1″-2″.
