KrF激光对高速飞片的驱动特性研究

利用诱导空间非相干技术平滑的KrF准分子（248nm）激光驱动带有烧蚀层的平面靶，研究激光空间均匀性对产生完整飞片的影响，结果表明激光不均匀性在2％以下，能够产生完整的高速飞片，且完整飞片能够维持20ns以上不破裂；当激光不均匀性达到5％，激光引入流体力学不稳定性种子应很强，冲击波在靶内输运过程中不稳定性不断发展增强，到靶背时强到足以使飞片解体甚至气化，不能产生完整的飞片。为了获得尽可能高的飞片速度，采用激光与烧蚀层参数不匹配方法，使冲击波对飞片作多次加速。利用功率密度为1012 W/cm2的KrF激光与含50μm Kapton烧蚀层的5μm铝飞片作用，得到速度约10km/s的高速飞片，与模拟结果吻合得很好。     

Improving regional ionospheric TEC mapping based on RBF interpolation

Radial basis function (RBF) interpolation with multi-quadric is developed to perform ionospheric total electron content (TEC) mapping for the Chinese region between 15°N ~ 40°N and 100°E ~ 125°E. TEC measurements from the Centre for Orbit Determination in Europe (CODE) covering the solar maximum year 2011 are used to investigate the performance of the proposed RBF interpolation method. The differences between the RBF interpolated TEC and the CODE TEC are within 0.5 TECU and the root mean square error (RMSE) is very small when 49 data points are used. The maximum difference is ~5 TECU and the error is less than 1 TECU with 25 samples. Our study suggests that a random distribution of measurement points gives smaller RMSEs than a homogenous distribution when the number of sample points is low. The study indicates that RBF interpolation offers a powerful and reliable tool for ionospheric TEC mapping.     

Numerical Simulation of Characteristics of CEX Ions in Ion Thruster Optical System

Charge exchange(CEX) ions could inflict severe damages on the ion thruster optical system. This article is aimed at investigating the characteristics of the CEX ions and their influences upon the optical system by means of particle-in- cell(PIC) ion simulation and Monte Carlo collision(MCC) methods. The results from numerical simulation indicate that despite the fact that CEX ions appear in the entire beamlet region near the ion optical system, the ones that present themselves downstream of the accelerator grid have good reason for attracting more attention. As their trajectories are significantly affected by the local electric field, a great number of CEX ions are accelerated toward grids resulting in sputtering erosion. When the influences of the CEX ions are considered in the numerical simulation, there could hardly be observed augments in the screen grid current, but the accelerator grid current increases from zero to 1. 4% of the beamlet current. It can be understood from the numerical simulation that the CEX ions formed in the region far downstream of the accelerator grid should be blamed for the erosion on the downstream surface of the accelerator grid.     

Novel radar target detection

Herein, a novel method of radar target detection based on 2-dimensional (2-D) fractal dimension is proposed. The proposed approach exploits both range information and azimuth information to estimate fractal dimension. Moreover, the approach can increase the number of data points. The above two merits result in the fractal dimension estimated by this method are more accurate and robust than the previous method. The detection performance is also better than the previous, which only makes use of 1-dimensional (1-D) information to estimate fractal dimension. Theoretical analysis and experimental results show that the proposed method performs well in a strong clutter background. The proposed method is also validated by real-life radar data, and the better result has been achieved.     

无速度传感器永磁同步电机直接转矩控制系统

详细阐述了零矢量在永磁直接转矩控制系统中的作用，指出如果合理应用零矢量，不仅能使永磁电机(PMSM)的DTC系统正常运行，而且能减少转矩脉动的频率和改善系统的性能。还研究了PMSM的DTC系统的无速度传感器技术，构建了包含零矢量在内的无速度传感器PMSM的DTC系统，仿真和实验都证明了理论的正确性。在无速度传感器的条件下，PMSM的DTC系统实现了宽范围调速，调速比达到了1：100。     

飞机静压系统气密性的等效检验

对静压系统的漏气进行数理分析，提出非气密性指标值新概念，运用这一新概念解决系统报密性等效检验问题，并据此计算出等效检验的气密性曲线。     

关于流行病的数学模型

本文给出了一般流行病的数学模型，并给出了模型的解和解释。     

三通道偏振导航传感器正交误差影响分析

根据三通道偏振导航传感器模型的测量原理,对模型中影响测量精度的偏振正交误差进行了分析和研究,推导出了三通道间偏振光轴的正交误差、定位初始角与定位角测量误差间的关系模型,对构建偏振导航定位系统具有重要的实际指导意义.     

二维边坡通用可靠性分析(英文)

通常应用可靠指标法分析二维边坡可靠性时，需要根据不同的条分法，按照不同的思路构造相应的功能函数进行分析，因而使得边坡可靠性的计算结果受到人为因素的影响。此外，该方法分析和推导的工作量相当大，迄今为止，只适合于垂直条分法。本文研究了以二维边坡稳定分析的Ｓａｒｍａ方法。Ｓａｒｍａ提出用一种虚拟的水平加速度来度量边坡的稳定性。本文导出了适合几种常用条分法的Ｓａｒｍａ加速度的一般表达式。根据Ｓａｒｍａ加速度的特点，可将其作为功能函数，由此得到的二维边坡可靠性分析方法具有通用性，并且适合于任何形式的条块划分。这样，可以方便地比较采用不同的条分法时对边坡可靠性的影响。本文在四种常用的条分法下计算了一个简单的算例。边坡材料的粘性系数和摩擦角被假定为随机变量。令每一随机变量的变异系数单独变化时，计算边坡的可靠性指标。结果表明，本文方法能很好地反映不同条分法之间的内在关系。通过改变边坡的条块形状，可以发现，本文的可靠性分析与以往基于Ｓａｒｍａ法的稳定性分析结果之间存在一致性。     

可减小跟踪误差的月球探测车协调驱动模糊自适应控制

 针对六轮月球探测车的协调驱动控制问题,提出一种间接模糊自适应控制设计方案。基于Lyapunov方法,证明所设计的控制方案不但能使跟踪误差收敛到原点的小邻域内,而且通过适当增大设计参数的值,可减小跟踪误差,从而提高控制精度。通过对月球探测车的协调驱动控制的仿真研究验证了此方法的有效性。