自触发脉冲激光测距飞行时间测量研究

提出一种新型脉冲激光测距方法——自触发脉冲飞行时间激光测距方法。运用该方法有效解决了传统脉冲激光测距法中存在的提高测量精度和缩短测量时间两者之间的矛盾。对该方法及本质特点进行了详细描述和理论分析,并给出用于描述该方法的基本方程。其飞行时间测量系统的设计很大程度上决定了自触发脉冲激光测距的测量精度和测量速度。设计并实现了基于CPLD的自触发脉冲激光测距飞行时间测量系统。CPLD的使用提高了测量精度,并且结构简单,体积小,可靠性高,非常适合高性能便携式的激光测距仪。     

自动增益控制的自触发脉冲激光测距技术

文中提出了一种具有自动增益控制的自触发脉冲测距方案,不但减小脉冲信号上升沿 引起的测距误差,而且也减小由于信号幅度变化带来的漂移误差影响。实验结果表明:该激光脉冲测距系统在1m～10m的测距范围内,测距精度达到亚毫米级。     

A low-jitter self-triggered spark-discharge pre-ionization switch:primary research on its breakdown characteristics and working mechanisms

MV pulsed switch plays a key role as the transfer switch in large electromagnetic pulse simulators.To broaden the range of self-triggering time,a novel spark-discharge pre-ionization switch,in which the main gap electric field is superposed at the trigger gap to let the electrons in its spark channel also become initial electrons,is proposed and tested.The design idea is:as electrons in the spark channel of the trigger gap always exist after its breakdown,the injection time of pre-ionization should have a more negligible effect on reducing the switch jitter.The experiment results under pulses with a rise time of～100 ns support the above assumptions.When the operating voltage is from～300 to～800 kV and the self-triggering time is～45％to～75％of the peak time,the breakdown time delay jitter is less than 2 ns,and the breakdown voltage jitter is smaller than 1.25％.Under specific self-triggering time,the breakdown time delay jitter is less than 1.5 ns,and the breakdown voltage jitter is smaller than 0.8％.     

河池串补装置火花间隙系统自触发原因分析

针对河池串补MOV在人工单相接地试验中火花间隙系自触发启动现象,基于河池串补火花间隙的工作原理,对串补装置火花间隙自触发进行分析和检测验证：人工单相接地试验与仿真计算表明串补电压VD测量装置可能存在较大误差,火花间隙自触发电压明显低于整定值,进一步对火花间隙进行检测,结果显示均压电容参数的变化使得火花间隙的自触发电压降低,从而导致了火花间隙的自触发。建议定期检测已投运串补装置的火花间隙参数,确保火花间隙正确动作。     

自触发脉冲飞行时间激光测距技术研究

提出了一种新型脉冲激光测距方法--自触发脉冲飞行时间激光测距方法.该方法有效解决了传统脉冲激光测距法中存在的提高测距精度和缩短测量时间两者之间的矛盾.对该方法及本质特点进行了详细描述和理论分析,并给出用以描述该方法的基本方程.最后,给出了实验装置,在20 m范围内获得了0.5 mm的测距精度.     

高能宇宙线探测数据采集前端的设计

介绍了一种具有快速硬件自触发功能的数据采集前端的设计,针对大面积多探测点的高能宇宙线实验的特殊情况,提出了独立自触发、数字化和数字滤波的实现方案。通过灵活的板级控制和兼容的PCB管脚设计,提供比较灵活的采样速率和采样精度的调整,以满足不同的需求。通过不同滤波器参数设置,实现对不同干扰信号的排除,完成信号的有效探测。     

Self-Triggering Mechanism of Vapor Explosions for a Molten Tin and Water System

The self-triggering mechanism of vapor explosions was investigated analytically and experimentally using molten tin and water. First, we modeled a simple droplet system consisting of a hot liquid droplet in a pool of cold liquid. Then, to model the self-triggering mechanism, we assumed that an instability (i.e. perturbed oscillation) in the vapor/cold-liquid interface produces a collapse of the vapor film, which in turn would produce a vapor explosion. To investigate the stability of perturbed oscillations in a vapor film, we did a linear stability analysis of a vapor film surrounding a hot liquid. We found that there was a region of film stability in the cold-liquid temperature where spontaneous vapor explosions did not occur.

To validate our model, we experimentally determined the thermal interaction zone (TIZ) in which spontaneous vapor explosions occur. The occurrence conditions for spontaneous vapor explosions were investigated for molten tin, as the hot liquid, dropped into a water pool, as the cold liquid. We varied the tin temperature and the water temperature, and then monitored the occurrence and location of spontaneous vapor explosions. We found that the upper limit for the water temperature of the TIZ can be explained by our model.     

基于CPLD 的脉冲激光测距飞行时间测量

研制了基于CPLD的脉冲激光测距飞行时间测量系统。CPLD的使用提高了激光测距仪的精度，并且可灵活修改设计，使同一硬件系统可用于不同类型的脉冲激光测距仪的飞行时间测量。此系统结构简单，体积小，可靠性高，非常适合高性能手持式脉冲激光测距仪。     

Robust tracking control for uncertain Euler–Lagrange systems via dynamic event-triggered and self-triggered ADP

This article investigates the robust tracking control problem for a class of Euler–Lagrange systems in presence of parameter uncertainties and external disturbances. Through system transformation and theoretical analysis, an adaptive dynamic programming (ADP) algorithm with two adaptive neural networks (NNs) and a suitable triggering mechanism is proposed to attain the robust stability of the closed-loop system. A single critic NN is leveraged to implement the approximate optimal controller design. Particularly, an NN-based feedforward compensation is developed to cope with the uncertainties with unknown bounds. Two different triggering mechanisms are respectively constructed to reduce the budget of sampling, communication and computation, namely the dynamic event-triggering mechanism (DETM) and the self-triggering mechanism (STM). The DETM is utilized to decide the update of remote controller and critic NN weight, which can yield a larger inter-event interval than the static event-triggering mechanism. Also, the Zeno-free behavior is guaranteed. Moreover, it is a novel attempt to introduce the STM into ADP design, which relaxes the demand of dedicated hardware online monitoring the event-triggering condition. Then it is demonstrated that all signals in the closed-loop system are uniformly ultimately bounded (UUB) via Lyapunov-based stability analysis. Finally, a simulation example of 2-link robotic system is implemented to verify the feasibility and effectiveness of the proposed algorithm.     

Experimental Study on Base-triggered Explosions in Molten-tin/Water Systems

The mechanism of explosions triggered at the bottom of a pool of liquid (i.e., base-triggered explosions) was experimentally investigated by dropping molten tin into water. We studied the effect of the tin temperature, the water temperature, the water depth, and the distance between the walls at the bottom of the pool on the tendency for explosions to occur. The experimental results showed that base-triggered explosions occurred at the bottom surface of the tank when the water temperature was near its saturation temperature. The occurrence of base-triggered explosions was also affected by the water depth. According to the interaction at the base, the observed explosions could be classified into two types: instantaneous and delayed explosions. The difference between the triggering mechanisms was explained by considering the homogeneous nucleation temperature of the water and the instantaneous interfacial temperature. The occurrence of delayed explosions was also affected by the distance between the side walls at the bottom of the pool. As the bottom surface area decreased, the tendency for base-triggered explosion increased.