应用遥编程的大时延遥操作技术

如何克服通信线路中的大时延和有限带宽,是空间遥机器人面临的最重要的一个问题．本文 阐述了应用遥编程技术提高大时延遥操作的稳定性和操作精度的基本思想．提出了一种将操 作区分段,采取复合控制策略的遥操作方法．同时介绍了基于遥编程概念的遥操作实验系统 的设计及其试验结果．     

Polycrystalline diamond MESFETs by Au-mask technology for RF applications

Metal-semiconductor field effect transistors (MESFETs) were fabricated on H-terminated polycrystalline diamond.The DC characteristics of the p-channel MESFET showed a maximum drain current density of 204 mA/mm at a gate-source voltage of 6 V,and a maximum transconductance of 20 mS/mm at a gate-source voltage of 1.5 V.The small signal S-parameters of MESFET with 2 100 m gate width and 2 m gate length were measured.An extrinsic cut-off frequency (fT) of 1.7 GHz and the maximum oscillation frequency (fmax) of 2.5 GHz were obtained,which was the first report on diamond MESFETs with RF characteristics in China.     

The aeroelastic effects on the scatter phenomenon of wind-tunnel data

The unsteady Reynolds-averaged Navier-Stokes equations coupled with the k SST turbulence model are solved to obtain the steady and unsteady aerodynamic forces for airfoils and wings.The effects of vibration types and amplitudes on aerodynamic forces of airfoils and wings are studied.The deformation characteristics of a swept wing induced by steady aerodynamic load are presented.It is found that for a vibrating elastic wing at small and medium incidences,its mean aerodynamic loads are almost the same as those obtained from the static one.On the contrary,at high incidences especially around the stall incidence,the vibration may change the mean values.In addition,the larger amplitude is,the larger discrepancy will be.For a swept wing,the steady aerodynamic loads usually lead to the "pitching down" effect on the wing tip which delays the stall compared with a rigid one;But this phenomenon dose not occur on a aeroelastic wing which can induce the separation ahead and trigger the stall.The above conclusions are in good agreement with the scatter characteristics of wind-tunnel data.The reason why the data obtained from wind tunnel and CFD are different is also analyzed.Meanwhile,it can be an explanation for scatter phenomenon of wind-tunnel data,especially for high incidence cases,which remains a puzzle so far.     

Globally stable adaptive robust tracking control using RBF neural networks as feedforward compensators

In previous adaptive neural network control schemes, neural networks are usually used as feedback compensators. So, only semi-globally uniformly ultimate boundedness of closed-loop systems can be guaranteed, and no methods are given to determine the neural network approximation domain. However, in this paper, it is showed that if neural networks are used as feedforward compensators instead of feedback ones, then we can ensure the globally uniformly ultimate boundedness of closed-loop systems and determine the neural network approximation domain via the bound of known reference signals. It should be pointed out that this domain is very important for designing the neural network structure, for example, it directly determines the choice of the centers of radial basis function neural networks. Simulation examples are given to illustrate the effectiveness of the proposed control approaches.     

金属表面脏污区域的分割和量化算法研究

针对目前金属表面缺陷检测技术的研究现状,主要研究金属表面脏污检测与量化算法。结合金属表面的特点,通过对几种分割方法的比较,研究了阈值分割法中的迭代法对图像进行分割,该算法能够最大限度地保留细节信息。另外,研究了一种改进的自适应滤波算法结合像素计数法对金属表面的脏污区域进行量化处理。实验结果证明了所提出方法的有效性。     

重质碳酸钙活化的研究

采用硬脂酸对1500目重质碳酸钙进行湿法活化,利用正交实验研究了硬脂酸加入量、反应温度和反应时间对活化效果的影响。测定了改性前后重质碳酸钙活化度,并用红外光谱进行表征。     

ERPN32-200离心泵机械密封失效原因分析

通过对ERPN32-200离心泵机械密封失效原因的分析,发现机械密封的实际密封效果不仅与机械密封自身的性能有关,而且与相关零部件的加工尺寸的精度等级以及维修时的装配质量有着重要的关系,同时针对不同的问题提出了相应的措施,延长了机械密封的使用寿命。     

对微波布拉格衍射实验中产生衍射极大值晶面的讨论

通过理论推导出三厘米微波布拉格衍射实验中的模拟晶体只能产生一、二级衍射,而且只有十个晶面可以产生衍射极大值,并且采用微波分光仪可以进行测量。本文还对这些晶面的特点进行了分析讨论,得出只要通过三个有代表性的晶面（晶面族）作为该实验的研究对象,就能够全面研究微波布拉格衍射实验,以便于从事这方面教学与研究的有关专业人士参考。     

装甲车车身自动调平系统原理及算法设计

为了提高6点装甲车辆调平的快速性和稳定性,根据装甲车结构,考虑响应时间、速度和可靠性等综合因素,将车身系统由6点调平系统等效为4点调平系统。利用相应的角度和压力传感器检测车架的水平状态,以确定油气簧的动作量。采用双速调整的方法计算比例阀门的开启大小及时间,运用西门子控制器实现对调平系统的控制。试验结果表明,该系统具有较高的快速性和稳定性。