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401.
针对近距航天器测距的需要,将CCSDS(空间数据系统咨询委员会)近距-1协议的定时业务与微波双向单程测距法相结合进行测距。该法以直序扩频技术来获得高精度传输帧ASM(附属同步标识)最后1位下降沿的时刻,并以时间码形式,通过帧数据域在测距星之间相互对传,综合考虑协议给出的信号物理特性,对所给出的方法进行了误差分析。分析表明,航天器之间距离不远,相对速度不大时,该法具有较高精度,且与数据通信共用1套设备,降低了成本。 相似文献
402.
M. Pandey A.P. Rao R. Manchanda P. Durouchoux C.H. Ishwara-Chandra 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2820-2823
We present the results of low frequency radio observations of the X-ray binaries, Cygnus X-1 and Cygnus X-3, during different X-ray states. The low frequency observations were made for the first time for these sources at 0.61 and 1.28 GHz using the Giant Meter-wave Radio Telescope (GMRT) between 2003 and 2004. Both Cyg X-1 and Cyg X-3 are highly variable at low radio frequencies. We also compare our data with the observations at 15 GHz conducted by the Ryle telescope. Spectral turnover is seen for both the sources below 2 GHz. The data suggest that the change in the radio flux density in both the sources is correlated to the X-ray hardness ratio and follows a similar behavior pattern. 相似文献
403.
小普托卷接机在烟厂中主要用于烟的生产试制,由于原机电气故障频发,维修费用昂贵,致使其无法正常运行,急需改造。改造后的系统采用FX2N PLC、FX2N-4D/A、MR-J2S-A伺服放大器、HC-KFS伺服电机以及F940GOT-SWD-C图形操作终端,实现了对烟支长度的控制。文中介绍了系统硬件组成、参数设定、软件设计以及运行结果。 相似文献
404.
臧天杰 《华北航天工业学院学报》2003,13(4):36-41
中日两国是一衣带水、隔海相望的近邻,有着两千多年的交往历史。在政治、经济、文化等诸多领域,两国人民始终有着密切的联系,特别是中国传统文化对日本本土文化的形成和发展产生了重大影响。本文通过在日本发现的大量中国文物,结合文献资料,从宏观上回顾了10世纪以前的中日物质文化交流。在此基础上,选取中国与日本发现的唐代铜镜为主要依据,在微观上对中日物质文化交流的实态、意义以及日本民族对待先进外来文化积极继承和发扬的态度进行思考、研究。 相似文献
405.
In 2012 we celebrate the 70th anniversary of the first successful rocket launch that reached a height of 84.5 km and had a speed of 4.824 km/h (5x sonic speed). This rocket flew 190 km to the target location. One of the masterminds of this launch was Walter Thiel, a German chemist and rocket engineer. Thiel was highly talented, during his education from primary school until diploma exams he always received a grade of A in his exams. He was called “the student with the 7 A grades”. In 1934 Thiel became Dr.-Ing. (chem.), with the highest possible honor (summa cum laude), when he was only 24 years old. He started to work for the rocket development department at Humboldt University, Berlin. Walter Dornberger asked him to leave the university research department and become head of rocket propulsion development in his team in Kummersdorf, near Berlin. Thiel's groundbreaking ideas for the rocket engine would lead to a significant reduction in material, weight and work processes, as well as a shortening in the length of the engine itself. Thiel and his team also defined the fuel itself and the best ratio of mixture between ethanol and liquid oxygen for the engine. In 1940 the propulsion team moved from Kummersdorf to Peenemünde after the launch sites were completed there. Thiel became deputy of Wernher von Braun at the R&D units. One of Thiel's team members was Konrad Dannenberg, who later became famous in the development of the Saturn program. On the night from August 17 to August 18, 1943, Thiel and his family (wife and two children) were killed during a Royal Air Force bombing raid (Operation Hydra). The Moon crater “Thiel” on the far side of the Moon is named after Walter Thiel. The research results of Walter Thiel had a strong impact on the United States' rocket program as well as the Russian rocket development program. 相似文献
406.
HY-1A is China's first ocean color satellite, and was launched on 15 May 2002as a piggyback satellite on the FY-1D satellite using the Long March rocket.There are two sensors on the satellite: China's Ocean Color and Temperature Scanner (COCTS), and the CCD Coastal Zone Imager (CZI). In the report,first, the properties and characteristics of HY-1A are briefly introduced; Second, the quality and availability of the data are evaluated by the mean of the Complex Signal Noise Ratio (CSNR) which is simulated theoretically; Third,the received HY-1A data are compared with SeaSTAR data to understand the accuracy of radiance measurement by the HY-1A; Finally, the remote sensing products of ocean color and temperature are mapped by HY-1A to study its application potentiality. The results show that the HY-1A has a latent capability for the application of marine environment detection, the management and protection of marine resources, and the furthering of national rights and interests.Meanwhile, some modifications are proposed for the next ocean satellite, suchas adding the case of tilt scanning, modification of the CCD element uniformity,and adding more ocean satellite receiving stations. 相似文献
407.
程湛汪光文苏和平 《民用飞机设计与研究》2014,(2):59-61
民用飞机的排烟能力直接影响到座舱出现烟雾情况下的飞行安全,对CCAR 25.831(d)条款和对应的咨询通告25-9A进行研究,为民用飞机座舱排烟的设计和适航验证提供支持。 相似文献
408.
409.
针对蜂群无人机快速充电排队问题,首次提出以平均队列长度和平均等待时间作为蜂群无人机充电排队优劣的评价指标。并通过理论分析和数值计算,在多充电平台的条件下,对蜂群无人机的分布式充电和集中式充电2种充电排队方式进行了比较和分析。得出蜂群无人机在泊松到达的条件下,随着服务强度的增加,评价指标对应的曲线出现了一个交叉点。在这个交叉点前,即服务强度较弱时,集中式充电排队方式优于分布式充电排队方式。在交叉点之后,即随着服务强度的增强,分布式充电排队方式将逐渐优于集中式充电排队方式。本文为蜂群无人机高效地完成任务提供了快速充电排队解决方案。 相似文献
410.