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排序方式: 共有646条查询结果,搜索用时 265 毫秒
631.
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633.
机翼缘条是连接飞机机翼与中央翼盒的重要结构件,其制造精度要求较高.喷丸强化后,该零件在啧丸残余应力的作用下会产生弯曲变形,需要通过优化不同位置的喷丸强化参数以减小弯曲变形量.首先,在喷丸强度的许可范围内进行了喷丸强化试验,并通过X衍射测量,建立喷丸参数与喷丸残余应力场间的函数关系;其次,设计Box-Behnken试验,通过等效喷丸变形模拟方法,得到了不同喷丸参数下机翼缘条的变形量,建立了缘条变形量与喷丸参数间的函数关系,根据Box-Behnken试验分析,结合工程条件得出了一组最优的喷丸强化参数;利用该组最优喷丸参数进行缘条的变形模拟和喷丸强化试验,发现喷丸变形的模拟与试验结果均较小,从而验证了缘条零件变形模拟和喷丸参数优化的有效性. 相似文献
634.
以创新党建为契机,促进独立学院学风建设 总被引:1,自引:1,他引:0
党建与学风建设具有相同的工作目标,二者相辅相成,相互渗透。学风建设是党建工作的有效载体,而党建工作是学风建设的内在支柱与重要环节。就目前独立学院学风建设中存在的诸多问题,试图以创新党建为契机,从加强思想政治教育、拓展宣传渠道、创新工作机制、完善评价体系四个方面来促进学风建设。 相似文献
635.
《中国航空学报》2022,35(12):1-31
The transmit antenna beampattern of the phased array radar is only a function of angle, limiting its ability to discriminate the targets from the same direction. Recently, the waveform diverse array radars expand the angle-dependent beampattern to an angle-time-range-dependent three-dimensional function by modulating the frequencies/time delays/phases across different transmit antenna elements. In this respect, extra Degrees-of-Freedom (DOFs) in the range domain are achieved, which opens up an innovative way to fulfil the tasks with enhanced system performance by jointly using the angle and range information. This paper summaries the developments of waveform diverse radars, including the Frequency Diverse Array (FDA), the Space-Time-Circulating-Array (STCA), and the Element-Pulse-Coding (EPC) frameworks, with emphasis on the analysis of the range-dependent beampattern from the basic properties upon how it is controlled. Moreover, the most recent advances of utilizing such a range-dependent beampattern in target detection, parameter estimation and identifiability, clutter suppression, jammer suppression and Synthetic Aperture Radar (SAR) imaging are discussed. 相似文献
636.
三维编织机锭子,轨道及锭槽结构尺寸的选择 总被引:3,自引:1,他引:2
分析了三维四步法编织机锭子运动的特点,提出了锭子与锭槽尺寸公差的选择原则;讨论了各种误差存在时,锭子可能窜入相邻轨道锭槽的情况,提出了防止锭子卡死或发生其它不良情况的结构措施,并举例进行了结构尺寸的选择。 相似文献
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638.
《中国航空学报》2023,36(5):406-420
A reasonable parameter configuration helps improve the data transmission performance of the Licklider Transmission Protocol (LTP). Previous research has focused mainly on parameter optimization for LTP in simplified scenarios with one to two hops or multihop scenarios with a custody mechanism of the Bundle Protocol (BP). However, the research results are not applicable to communications in Complex Deep Space Networks (CDSNs) without the custody mechanism of BP that are more suitable for deep space communications with LTP. In this paper, we propose a model of file delivery time for LTP in CDSNs. Based on the model, we propose a Parameter Optimization Design Algorithm for LTP (LTP-PODA) of configuring reasonable parameters for LTP. The results show that the accuracy of the proposed model is at least 6.47% higher than that of the previously established models based on simple scenarios, and the proposed model is more suitable for CDSNs. Moreover, the LTP parameters are optimized by the LTP-PODA algorithm to obtain an optimization plan. Configuring the optimization plan for LTP improves the protocol transmission performance by at least 18.77% compared with configuring the other parameter configuration plans. 相似文献
639.
《中国航空学报》2022,35(8):75-91
Experimental and numerical studies are carried out to validate the potential of opposing Plasma Synthetic Jet (PSJ) for drag reduction for a hemisphere. Firstly, flow field changes of opposing PSJ are analyzed by comparing the experimental schlieren images and simulation results in a supersonic free stream of Mach number 3. As PSJ is a kind of unsteady pulsed jet, the shock standoff distance increases initially and then decreases under the control of PSJ, which corresponds to the change of the strength of PSJ. Accordingly, the amount of drag reduction of the hemisphere increases initially and then decreases. It is found that there is a short period of “drag rise” during the formation of PSJ before the drag reduction, which is induced by the generation of normal shock waves and the area difference of the cavity wall of PSJ Actuator (PSJA). Secondly, the effects of five parameters, including exit diameter, discharge energy of PSJA, Mach number, static pressure of incoming flow and angle of attack, on drag reduction of opposing PSJ were studied in detail by using numerical method. It is found that the Maximum Pressure Ratio (MPR) has a significant impact on the average drag reduction for a configuration-determined PSJA. For the configuration selected in this study, the flow field of opposing PSJ shows typical Short Penetration Mode (SPM) in a control cycle of PSJ when the MPR is less than 0.89. However, the flow field shows typical Long Penetration Mode (LPM) at some time when the MPR is bigger than 0.89. Relatively better drag reduction is achieved in this case. 相似文献
640.