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861.
介绍新型号发动机试车台在设计过程中,利用局域网进行大量的 CAD 工作,实现相关资源的共享,降低投资费用,避免重复性的工作,可节约大量的人力物力。主要介绍了 CAD 局域网的作用、网络的拓扑结构、网络设备和相关软件的选择。 相似文献
862.
“天问一号”火星探测器超高频(Ultra high frequency, UHF)频段中继通信系统作为中国首次火星探测任务实现的重要组成部分,负责为着陆巡视器与环绕器之间在火星进入、下降、着陆阶段(Entry, descent and landing, EDL)与火面巡视阶段提供高效可靠的通信服务。本文对中国火星探测器UHF频段中继通信方案进行了介绍,给出中继通信系统的组成、技术指标及链路设计方法,并对在轨飞行试验数据进行了分析。结果表明,全新研制的“天问一号”探测器UHF频段中继通信系统圆满完成了任务目标,其设计、实现和应用为后续中国深空中继通信系统研制提供了技术参考。 相似文献
863.
In order to perform an optical assembly accurately, a multi-sensor control strategy is developed which includes an attitude measurement system, a vision system, a loss measurement system and a force sensor. A 3-DOF attitude measuring method using linear variable differential transformers (LVDT) is designed to adjust the relation of position and attitude between the spher- ical mirror and the resonator. A micro vision feedback system is set up to extract the light beam and the diaphragm, which can achieve the coarse positioning of the spherical mirror in the optical assembly process. A rapid self-correlation method is presented to analyze the spectrum signal for the fine positioning. In order to prevent the damage of the optical components and realize sealing of the resonator, a hybrid force-position control is constructed to control the contact force of the optical components. The experimental results show that the proposed multi-sensor control strategy succeeds in accomplishing the precise assembly of the optical components, which consists of parallel adjustment, macro coarse adjustment, macro approach, micro fine adjustment, micro approach and optical contact. Therefore, the results validate the multi-sensor control strategy. 相似文献
864.
865.
The Forming Limit Curve (FLC) of the third generation aluminum-lithium (Al-Li) alloy 2198-T3 is measured by conducting a hemispherical dome test with specimens of different widths. The theoretical prediction of the FLC of 2198-T3 is based on the M-K theory utilizing respectively the von Mises, Hill'48, Hosford and Barlat 89 yield functions, and the different predicted curves due to different yield functions are compared with the experimentally measured FLC of 2198-T3. The results show that though there are differences among the four predicted curves, yet they all agree well with the experimentally measured curve. In the area near the planar strain state, the predicted curves and experimentally measured curve are very close. The predicted curve based on the Hosford yield function is more accurate under the tension-compression strain states described in the left part of the FLC, while the accuracy is better for the predicted curve based on Hill'48 yield function under the tension-tension strain states shown in the right part. 相似文献
866.
The Forming Limit Curve (FLC) of the third generation aluminum-lithium (Al-Li) alloy 2198-T3 is measured by conducting a hemispherical dome test with specimens of different widths. The theoretical pred... 相似文献
867.
红外 可见光双目系统既能感知目标的温度,又能获取目标的颜色、纹理信息,在日常生活和工业产生中获得较多的应用.红外相机由于和可见光相机成像机制的不同,在标定过程中往往需要使用不同的靶标.本文提出了一种红外 可见光双目系统像素级的快速标定融合方法,通过设计了一种圆孔形靶标,实现了一步法标定,在可见光相机像素坐标系下像素质心标定精度小于1个像素,可用于大批量的低成本的民用红外标定产品系统. 相似文献
869.
Jing Sun Geshi Tang Fengchun Shu Xie Li Shushi Liu Jianfeng Cao Andreas Hellerschmied Johannes Böhm Lucia McCallum Jamie McCallum Jim Lovell Rüdiger Haas Alexander Neidhardt Weitao Lu Songtao Han Tianpeng Ren Lue Chen Mei Wang Jinsong Ping 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(3):823-829
The APOD (Atmospheric density detection and Precise Orbit Determination) is the first LEO (Low Earth Orbit) satellite in orbit co-located with a dual-frequency GNSS (GPS/BD) receiver, an SLR reflector, and a VLBI X/S dual band beacon. From the overlap statistics between consecutive solution arcs and the independent validation by SLR measurements, the orbit position deviation was below 10?cm before the on-board GNSS receiver got partially operational. In this paper, the focus is on the VLBI observations to the LEO satellite from multiple geodetic VLBI radio telescopes, since this is the first implementation of a dedicated VLBI transmitter in low Earth orbit. The practical problems of tracking a fast moving spacecraft with current VLBI ground infrastructure were solved and strong interferometric fringes were obtained by cross-correlation of APOD carrier and DOR (Differential One-way Ranging) signals. The precision in X-band time delay derived from 0.1?s integration time of the correlator output is on the level of 0.1?ns. The APOD observations demonstrate encouraging prospects of co-location of multiple space geodetic techniques in space, as a first prototype. 相似文献