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本文介绍了固体润滑技术的润滑机理和影响因素,结合涡旋真空泵的结构特点,对固体润滑技术在涡旋真空泵的应用进行了分析研究。 相似文献
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在相干分布式非圆(CDNC)信号波达方向(DOA)估计中,针对阵列输出矩阵扩展后维数增加带来的较大运算量问题,基于降维的多级维纳滤波(MSWF)技术,引入回溯优化思想,提出了一种快速估计算法。该算法首先利用信号非圆特性扩展阵列输出矩阵,然后通过MSWF递推分解快速求出信号子空间,避免了计算阵列协方差矩阵及特征分解,并且在递推过程中引入回溯优化机制提高了各级匹配滤波器的估计性能,最后由最小二乘(LS)或者总体最小二乘(TLS)得到DOA估计。仿真分析表明,所提算法与相干分布式非圆信号旋转不变子空间算法(CDNC-ESPRIT)性能相当,但复杂度得到了大幅度降低,相比于基于MSWF的非圆信号快速子空间(NC-MSWF-FS)算法,在较小的复杂度代价下大幅度提升了低信噪比时的估计性能,并且对初始参考信号的选取具有了较强的鲁棒性。 相似文献
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B. A. Whalen D. J. Knudsen A. W. Yau A. M. Pilon T. A. Cameron J. F. Sebesta D. J. McEwen J. A. Koehler N. D. Lloyd G. Pocobelli J. G. Laframboise W. Li R. Lundin L. Eliasson S. Watanabe G. S. Campbell 《Space Science Reviews》1994,70(3-4):541-561
The F3C Cold Plasma Analyzer (CPA) instrument on theFreja spacecraft is designed to measure the energy per unit charge (E/Q) of ions oe electrons in the range 0<E/Q<200 V and complements the observations made by the F3H Hot Plasma Experiment. The CPA sensor, which is deployed on a boom, is an electrostatic analyzer which produces angle/energy images of particles incident on the sensor in a plane perpendicular to the boom axis. Charged particles incident normal to the CPA sensor housing axis of symmetry, which coincides with the boom axis, pass through collimators and enter a semi-spherical electrostatic analyzer which disperses particles in energy and azimuthal angle of arrival onto an imaging MCP detector thus producing images of the particle distributions in a plane perpendicular to the boom axis. Measurements are transmitted either as discrete 16×16 (angle/energy) images or as parameters related to the incident particle distribution function. Pixels in the discrete images are separated approximately equally in azimuthal angle while the 16 energy bins are separated approximately geometrically in energy. The ratio of the maximum to minimum energy imaged is programmable up to a maximum of more than a factor of ten, and the energy range itself is also under the control of the processor and can be varied by more than an order of magnitude. The density dynamic range of the sensor is increased by the introduction of an electrostatic gating system between the entrance aperture and the analyzer which can be used to duty-cycle low-energy electrons into the sensor thus keeping the count rate within appropriate levels. To reduce the effects of spacecraft induced perturbations on the lower-energy particle distributions, the sensor portion of the instrument is deployed on a 2 m long boom, perpendicular to the spacecraft spin axis. Spacecraft rotation is used to recover complete (4) angle/energy distributions every half spin period. In addition, the sensor skin may be biased with respect to the spacecraft ground to offset effects due to spacecraft charging. Current to the skin is monitored, making the exterior of the sensor equivalent to a large cylindrical Langmuir probe. Two separate processing paths for signals from the MCP anode may be chosen; slow and rast. The slow pulse processing path provides discrete angle/energy images at a nominal rate of 10 images per second and a peak burst mode rate of 100 images per second. The fast analog or current mode path provides crude parameterized estimates of densities, temperatures and drift velocities at nominal rates of up to 1000 parameters per second with a burst rate near 6000 parameters per second. Observations of cold ions and electrons in an unperturbed ionospheric plasma are presented which demonstrate the functionality of the instrument. Suprathermal ion observations in a transverse ion energization or acceleration region are also shown which demonstrate many of the small-scale features of these events.The Canadian Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledge. 相似文献
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为了研究高温基线密封中的编织弹簧的回弹特性,参照Pierce线圈模型对编织弹簧管进行参数化建模。采用有限元软件对编织弹簧管进行静力学仿真,对比有限元计算结果与实验数据,接触面摩擦因数为0. 1时仿真结果与实验结果吻合较好。弹簧刚度对线径十分敏感,回弹力与线径呈现非线性高次关系。增加编织线股数,弹簧刚度会成倍增加。温度在低于600℃时对弹簧刚度的影响较小,在高于600℃后,弹簧刚度随着温度升高快速下降。通过S-N曲线计算编织弹簧管在650℃时的最低疲劳寿命高于密封设计要求。研究结果表明,在编织弹簧管的设计要求的前提下,环密度为0. 05、线径为0. 32 mm、双线编织的编织弹簧管具有较好的性能。。 相似文献
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针对四足机器人在辅助作业背景下,通过远程遥控或地面站控制难以满足人机灵活交互需求的问题,在研究实现四足机器人基本步态控制基础上,结合无线定位和激光雷达感知环境赋予机器人避障和人员跟随功能,采用Openpose姿态识别方法,通过视觉传感器进行人机交互,实现不同姿态对机器人基本运动行为和跟随任务的控制,并基于ROS系统开展不同环境条件下交互识别和控制效果测试,姿态识别速度为20帧/s,理想环境下准确度大于90%,机器人反应时间小于1 s。 相似文献
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