微波注入反相器基本电路的非线性效应

采用理论分析和微波注入实验相结合的方法,分别研究了以74HC04和74LVCU04A两种芯片为核心的反相器基本缓冲及数模转换电路的微波效应问题,通过反相器闩锁过程对非线性扰乱进行了机理分析,并利用微波注入实验详细分析了非线性扰乱效应的微波有效功率阈值及其随频率、脉冲宽度的变化。实验结果表明:在固定环境温度条件下,有效注入功率大于33 dBm,频率在3 GHz以下的微波均可使74HC04效应电路的非线性扰乱强度达到10%以上;有效注入功率大于30 dBm,频率在3 GHz以下的微波均可使74LVCU04A效应电路的非线性扰乱强度达到10%以上。相同非线性扰乱强度的注入有效功率阈值近似随频率的提高而增大。非线性扰乱阈值随注入微波信号脉宽变化明显,拐点为40~70 ns不等,与反相器中的互补型金属氧化物半导体器件寄生三级管的导通电流积累有关。     

用于高热流密度器件冷却的热管散热器实验研究

针对大型计算机服务器CPU的耗能量,探讨了一种新的热管排布方式的散热器,并对其散热性能进行了实验研究.研究结果表明,采用此种热管散热器,最高热流密度为74.3W/cm2,其冷却风速控制在4m/s即可满足芯片冷却要求.同时根据模拟计算得到的散热器底板温度分布,可有助于对热管排布方式的优化设计.     

大型激光装置束间能量平衡能力综合分析方法

 针对大型激光装置输出能量平衡能力,建立了束间均方根分析方法。构建了大型激光装置的光束能量观测数据变换过程,得到服从近似正态分布的变换数据,从而建立简便的束间能量平衡能力的均方根计算方法;基于全控图和选图,针对装置能量平衡能力短期变化提出均方差控制图,并定义装置平均失效强度函数,用于描述装置整体的能量平衡能力长期变化趋势。通过对调试数据的分析,验证了综合分析方法的可视性和高效性。     

基于稀疏活动轮廓模型的感兴趣目标检测定位算法

传统的基于形状信息目标定位的算法,对目标观测角度发生形变情况下的定位存在不少困难,针对该问题,提出了一种基于稀疏活动轮廓模型的感兴趣目标(OOI)检测算法.首先通过共同勾画算法学习到感兴趣目标的稀疏活动轮廓模型,它能够清晰地定义感兴趣目标模式;同时构成该模型的Gabor轮廓基元可以通过扰动进行局部的调整以适配图像,在一...     

Second order gradient ascent pulse engineering

We report some improvements to the gradient ascent pulse engineering (GRAPE) algorithm for optimal control of spin ensembles and other quantum systems. These include more accurate gradients, convergence acceleration using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) quasi-Newton algorithm as well as faster control derivative calculation algorithms. In all test systems, the wall clock time and the convergence rates show a considerable improvement over the approximate gradient ascent.     

Vibration control of the finite L-shaped beam structures based on the active and reactive power flow

This paper analyzes the physical meaning of the active and reactive power flow in the finite L-shaped beams and studies the active vibration control of the structures based on the active and reactive power flow.The traveling wave approach is used to calculate the structural dynamic responses.Because the error of control force is inevitable in practical applications,the effects of the error of control force on the control results are studied.The study indicates that the error of control force has pronounced ...     

Analysis of statistical nature of electrical breakdown time delay in nitrogen at 6.6 mbar pressure in presence of positive ions and N(4S) atoms

On the basis of the mean value of electrical breakdown time delay and the standard deviation of electrical breakdown time delay σ dependence on the afterglow period τ, the mechanisms which dominantly influence to breakdown initiation in nitrogen were separated. It was shown that the positive ions formed in mutual collision of long‐lived metastable molecules have a dominant role in breakdown initiation for τ values up to 70 ms. The metastable molecules were derived from previous breakdown and discharge. In this case σ ≪ t_d and the total time delay t_d is approximately equal to formative time t_f which decreases in value with the increase of overvoltage. When positive ions have a dominant role in the breakdown initiation the Gaussian distribution describes data of t_d ≈ t_f very well. For τ > 1 s, N (⁴S) atoms formed in previous breakdown and discharge, have a dominant role in the breakdown initiation. Then, σ ≈ and Laue's distribution, which is valid for statistical time delay t_s, describes t_d data very well (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

利用阿秒激光追踪和控制原子分子内部电子的运动

随着强激光技术的快速发展, 在物质与激光相互作用下,实验上发现了很多新奇的物理现象。这些现象成功地被各种理论模型和数值模拟所解释和证明。一种很重要的现象就是所谓的高次谐波产生：在原子和分子与强激光相互作用时, 能够放出能量为基频光子能量几倍到几百倍的大能量光子。在实验上, 人们已经可以通过合成截止频率附近的几个谐波来产生脉冲长度在阿秒量级的激光脉冲（1阿秒=10-18秒）。阿秒脉冲的获得开启了超快科学一个全新的领域：人们可以在电子运动的自然时间尺度上去探测和操控原子分子内部电子的运动,这是继飞秒科学后人们操控微观世界物质运动的又一大飞跃。在本文中,我们就最近几年我们在理论上所开展的阿秒物理做一个简单的综述,重点强调利用阿秒光去控制电子的电离动力学以及探测分子内部电子运动.     

基于Matlab/Simulink的电压型超导储能功率调节控制仿真

本文首先对电压型超导储能（Voltage-Superconducting-Magnet-Energy-Storage,简称VSMES）功率调节系统（Power-Conditioning-System,简称PCS）的原理进行介绍,并运用Matlab/Simulink仿真分析软件,针对三相电压型超导储能功率调节系统的控制过...     

扰动Nizhnik-Novikov-Veselov系统分形孤子渐近解

文章研究了一类扰动Nizhnik-Novikov-Veselov非线性系统, 利用特殊的渐近方法得到了相应系统分形孤子渐近解. 关键词： 孤子 渐近解 扰动