建立高校毕业生跟踪工作机制的调查与思考

从毕业生跟踪调查形式、时间、次数、范围、内容等方面分析高校目前跟踪调查工作的现状,探索毕业生跟踪调查的方法和规律,对建立毕业生跟踪调查长期有效机制提出几点建议,对进一步提高毕业生跟踪调查工作水平具有一定的借鉴价值。     

自动倒码式力标准机技术及其应用

静重式力标准机是最重要的力值计量、传递仪器之一。采用倒换砝码的加载方法,只需少量的砝码,可以实现大范围测量应用,并减小设备体积。理论上,一台较大规格的自动倒码式力标准机可以替代其容量以下所有规格的设备。分析了加载过程中砝码倒换的力学原理,论述了所研制的自动倒码式力标准机的工作原理及其自动监控问题,并进行了应用实验。结果表明,关于砝码倒换的力学原理的理论分析和力标准机的监控方法是正确和有效的。自动倒码式力标准机非常适合于包括宇航推力计量器具在内的各种测力仪的标定和校准。     

基于SPCE061A数字四探针电阻率测试仪的设计

以16位单片机SPCE0 6 1A为控制核心,并采用内带程控放大器和片上数字滤波器的16位Σ-Δ型模数转换器AD770 5 ,设计了一款智能四探针电阻率测试仪的硬件电路。该仪器能够自动选择量程和自动校准,本设计减小了印刷电路板的面积,提高了测试仪器的智能化水平,具有一定的实用开发价值。     

航空电子设备自动化测试及关键技术研究

在介绍航空电子设备自动测试技术的基础上 ,分析了航空电子设备自动化测试的关键技术 ,指出宽带微波系统、射频信号仿真和故障自动诊断是航空电子设备自动化测的关键技术。     

基于粒子滤波算法的非刚性目标实时跟踪

基于颜色的粒子滤波实时跟踪算法主要是利用视频图像的颜色直方图信息,综合考虑运动预测和帧间的相似性来确定目标的位置。针对影响粒子滤波算法性能的关键技术,提出了基于混合高斯模型的粒子滤波算法,并将其用于基于颜色的非刚性目标的实时跟踪相关问题。该算法使用混合高斯模型表示粒子,在每个时刻的修正步骤之后,采用EM算法对粒子进行重新拟合。仿真实验表明,本算法在保证跟踪准确度的同时,可以满足实时跟踪的要求。     

在SKA设计中实现干扰零点形成的方法

在SKA(平方千米阵列)的设计中,采用相控阵技术的一个原因是想利用其自适应零点形成技术来抵抗频率干扰。介绍了一种在该类系统中适用的自适应算法PASTd,该方法利用子空间跟踪技术区分子空间,然后据此在干扰方向形成深的零点。在一小型相控阵中的仿真结果表明该方法简单、收敛快且比较精确。     

基于矩阵光学的多程激光放大器准直系统模型分析

多程放大技术成为高功率固体激光装置的主要发展方向,对激光光路进行调试和维护,建立光路准直的数学模型和调整方案很有必要,采用矩阵光学方法,建立了多程放大自动准直系统数学模型,得出了远、近场光斑偏移量与调整量的解析表达式,验证了该自动准直系统光路原理及调整方法的可行性。     

Lock threshold deterioration induced by antenna vibration and signal coupling effects in hypersonic vehicle carrier tracking system of Ka band

The envelope of a hypersonic vehicle is affected by severe fluctuating pressure, which causes the airborne antenna to vibrate slightly. This vibration mixes with the transmitted signals and thus introduces additional multiplicative phase noise. Antenna vibration and signal coupling effects as well as their influence on the lock threshold of the hypersonic vehicle carrier tracking system of the Ka band are investigated in this study. A vibration model is initially established to obtain phase noise in consideration of the inherent relationship between vibration displacement and electromagnetic wavelength. An analytical model of the Phase-Locked Loop(PLL), which is widely used in carrier tracking systems, is established. The coupling effects on carrier tracking performance are investigated and quantitatively analyzed by imposing the multiplicative phase noise on the PLL model. Simulation results show that the phase noise presents a Gaussian distribution and is similar to vibration displacement variation. A large standard deviation in vibration displacement exerts a significant effect on the lock threshold. A critical standard deviation is observed in the PLL of Binary Phase Shift Keying(BPSK) and Quadrature Phase Shift Keying(QPSK) signals. The effect on QPSK signals is more severe than that on BPSK signals. The maximum tolerable standard deviations normalized by the wavelength of the carrier are 0.04 and 0.02 for BPSK and QPSK signals,respectively. With these critical standard deviations, lock thresholds are increased from à12 andà4 d B to 3 and à2 d B, respectively.     

High performance motion control for optical satellite tracking systems

This paper investigates the motion control system of an optical telescope system used for precision satellite tracking and ranging applications. The system uses direct-drive permanent magnet synchronous motors (PMSMs) for high precision positioning. To overcome the performance limitations due to system dynamics and position dependent plant variations, a disturbance observer based control system is utilized. This paper contributes the detailed analysis, design and implementation of such an advanced control concept for the performance improvement of precision satellite tracking systems. Satellite tracking experiments are conducted to verify the performance of the proposed system. Utilizing the proposed control concept, the RMS servo error is reduced by a factor of 3.8 to well below the arcsecond range, achieving seeing limited tracking.     

Loopy belief propagation based data association for extended target tracking

The data association problem of multiple extended target tracking is very challenging because each target may generate multiple measurements. Recently, the belief propagation based multiple target tracking algorithms with high efficiency have been a research focus. Different from the belief propagation based Extended Target tracking based on Belief Propagation (ET-BP) algorithm proposed in our previous work, a new graphical model formulation of data association for multiple extended target tracking is proposed in this paper. The proposed formulation can be solved by the Loopy Belief Propagation (LBP) algorithm. Furthermore, the simplified measurement set in the ET-BP algorithm is modified to improve tracking accuracy. Finally, experiment results show that the proposed algorithm has better performance than the ET-BP and joint probabilistic data association based on the simplified measurement set algorithms in terms of accuracy and efficiency. Additionally, the convergence of the proposed algorithm is verified in the simulations.