A LM-3B carrier rocket sits on the launch pad waiting for launch Photo:XIAO Guojun

China successfully sent the 52nd and 53rd satellites of the BeiDou Navigation Satellite System (BDS)into their preset orbit with a LM-3B/Yuanzheng 1 launch vehicle from the Xichang Satellite Launch Center at 15:22 Beijing time on December 16,2019.

The launch marked the fact 24 MEO satellites of BDS-3 have all been successfully launched into space,and the deployment of the core BDS-3 constellation system has been completed,further improving service performance and the user experience,thus laying a solid foundation for global networking.

The two BeiDou-3 MEO satellites were developed by the China Academy of Space Technology (CAST)under CASC.As the main force of the BDS-3 constellation system,the satellites mainly provide navigation,positioning and timing services,as well as global short message communication and international search and rescue services for global users.

The LM-3B/Yuanzheng 1 launch vehicle was developed by the China Academy of Launch Vehicle Technology (CALT).It is a member of the LM-3A series launch vehicle family which is composed of a basic stage and an upper stage.

該區(qū)域加深鉆井采用高密度鉆井液支撐井壁，提高抑制性能防止泥頁巖水化分散脫落，并選擇合適鉆井工藝防塌措施的施工方案。以152井為例，該井鉆井液密度控制為1.85～1.90g／cm3，漏斗黏度為50～70s，pH值為9～11，切力為（8～12）／（15～20）Pa／Pa，動(dòng)切力為12～16Pa，塑性黏度為25～35mPa·s，常規(guī)濾失量為3～5mL，高溫高壓濾失量（150℃）為8～10mL，固相含量36%～40%，含砂量為0.3%～0.5%。

A LM-3B/Yuanzheng 1 launch vehicle is lifting off from the Xichang Satellite Launch Center,sending two BeiDou satellites into orbit Photo:XIAO Guojun

Up to now,the LM-3A series launch vehicle has successfully completed all the 12 missions in 2019 which is about 50% of the missions of LM series launch vehicle,becoming the most frequently launched carrier rocket in China for 5 years in a row.

具體的做法以我公司需要開發(fā)的產(chǎn)品或教學(xué)資源為校企合作課題，讓學(xué)校的骨干教師來參與合作開發(fā)軟硬配套的新產(chǎn)品，這樣可以達(dá)到培養(yǎng)