半导体桥等离子体温度的原子发射光谱法测量

半导体桥生成的等离子体由于温度高、尺度小、持续时间短等特点,对其温度的瞬态测量是个难题.本文采用高速数字存贮示波器应用原子发射光谱双谱线法对半导体桥等离子体温度进行了实时瞬态测量,并对在22μF电容下不同充电电压对半导体桥等离子体温度的影响进行了系统的研究,得到了22μF电容下等离子体最高温度与充电电压的关系式Tmax=700.6 115.2U.     

基于数字粒子图像测速的水雾粒径测量算法及实验

针对利用传统数字粒子图像测速（DPIV）法测量水雾粒径时粒子影像拉长对测试结果的影响,提出了基于DPIV建立的改进图像法（IIM）。设计了水雾粒径测量试验系统,对细水雾进行实时测试,并对比了采用本文算法与直接等效法测试水雾粒径子半径的差异。结果表明：采用本文的IIM得到的测试结果更为准确。通过最小二乘法对粒径分布进行拟合,发现对数正态分布函数和威布尔函数都可以较好地描述粒径分布。     

传输线中脉冲信号反射波的测量和应用

将高频单脉冲信号输入同轴电缆，借助数字存储示波器记录输入、输出端的波形和相对延时，可以测量传输线的电缆长度和衰减系数，同时观察脉冲波形因色散引起的畸变．     

Effects of initial frequency chirp on the linear propagation characteristics of the exponential optical pulse

In this paper, the linear propagation characteristics of the exponential optical pulse with initial linear and nonlinear frequency chirp are numerically studied in a single mode fibre for \be₂<0. It can be found that the temporal full width at half maximum and time-bandwidth product of exponential pulse monotonically increase with the increase of propagation distance and decrease with the increase of linear chirp C for C<0.5, go through an initial decreasing stage near \zeta=1, then increase with the increase of propagation distance and linear chirp C for C\geq0.5. The broadening of pulses with negative chirp is faster than that with positive chirp. The exponential pulse with linear chirp gradually evolves into a near-Gaussian pulse. The effect of nonlinear chirp on waveform of the pulse is much greater than that of linear chirp. The temporal waveform breaking of exponential pulse with nonlinear chirp is first observed in linear propagation. Furthermore, the expressions of the spectral width and time-bandwidth product of the exponential optical pulse with the frequency chirp are given by use of the numerical analysis method.     

电荷平衡和自动跟踪型加速度计电流数字转换

针对惯性导航系统现有加速度计电流信号转换电路的不足,提出了一种基于电荷平衡和自动跟踪原理的加速度计电流数字转换方法（CDC）,从工作原理上大幅提升转换电路性能。CDC对输入电流和反馈跟踪电流积分输出误差电压,依据该误差电压实时调整其数字输出d以及与d成比例的反馈跟踪电流,实时反馈控制使误差电压稳定在0附近,实现输入电流和反馈跟踪电流二者电荷平衡。设计了单路CDC电路用于原理验证和性能测试。实验表明,±40 mA电流范围内CDC电路标度因数不对称性优于5 ppm,非线性优于10 ppm,电流分辨率优于0.5 nA,动态范围大于164 dB;采用查找表技术补偿后-40℃～+60℃温度区间零偏变化小于30 nA、标度因数变化小于20 ppm,且各性能指标均有较大改善空间。电荷平衡和自动跟踪型加速度计电流数字转换技术具有动态范围大、精度高、分辨率高、易补偿等优点,具有非常好的应用前景。     

Bifurcation Control of Current-Mode Buck Converter via TDFC

Considering the TDFC controlled current-mode Buck converter featuring periodicity we propose a Fourier-decomposition based method for the bifurcation analysis of this system, hence the theoretical range of control gain of TDFC is determined. In addition, the power-stage experiment circuit is built and the control part is realized in a digital controller. The experimental results show that either bifurcation or chaos in the current-mode Buck converter can be controlled into the expectant period-1 orbit rapidly.     

恒定非均匀磁场调控下的强制对流传热数值研究

分别对雷诺数、磁场强度和磁纳米流体浓度进行了讨论，并将数字高程模型(DEM)应用到梯度磁场模型的建立，分析了磁场梯度大小和方向对传热效果的影响。结果表明：雷诺数、磁场强度和梯度与传热效果呈正相关，在磁场介入的情况下，磁纳米流体浓度对传热效果的影响存在一个最佳值；磁场梯度方向垂直于流动方向时对传热的强化效果最显著。以平均努塞尔数和压降为目标参数，利用正交试验设计的方法研究了各变量对传热效果影响的权重大小，得到各变量取值范围内的最佳组合。     

由巧合引发的数学研究

乔治.兰伯特是美国加利福尼亚州一所中学的数学教师,他除了对自己的专业——数学特别敏感外,还对历史上的离奇巧合事件具有浓厚兴趣,并力图用数学的方式来破解巧合.     

Numeral eddy current sensor modelling based on genetic neural network

This paper presents a method used to the numeral eddy current sensor modelling based on the genetic neural network to settle its nonlinear problem. The principle and algorithms of genetic neural network are introduced. In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network （GNN） according to measurement data. So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network. The nonlinear model has the advantages of strong robustness, on-line modelling and high precision. The maximum nonlinearity error can be reduced to 0.037% by using GNN. However, the maximum nonlinearity error is 0.075% using the least square method.     

Two-vibron bound states in the β--Fermi--Pasta--Ulam model

This paper studies the two-vibron bound states in the β- Fermi Pasta-Ulam model by means of the number conserving approximation combined with the number state method. The results indicate that on-site, adjacent-site and mixed two-vibron bound states may exist in the model. Specially, wave number has a significant effect on such bound states, which may be considered as the quantum effects of the localized states in quantum systems.