Hamilton系统的动力学稳定性

主要介绍了Hamilton系统动力学所研究的问题,介绍了在Hamilton系统稳定性研究方向近年来的进展.例如:KAM理论、Mather理论、Arnold扩散等.     

Application of wavelet-based active power filter in accelerator magnet power supply

Since modern accelerators demand excellent stability to magnet power supply(PS), it is necessary to decrease harmonic currents passing magnets. Aiming at depressing the rappel current from the PS in the Beijing electron-positron collider, a wavelet-based active power filter(APF) is proposed in this paper. An APF is an effective device to improve the quality of currents. As a countermeasure to these harmonic currents, the APF circuit generates a harmonic current, countervailing harmonic current from PS. An active power filter based on wavelet transformation is proposed. Discrete wavelet transformation is used to analyze the harmonic components in the supply current, and an active power filter circuit works according to the analysis results. Our simulation and experiment results are given to prove the effect of the APF.     

MPT-X装置电源回路的计算及实验

磁约束聚变实验装置的一个重要问题是它的各个磁场线圈的放电回路的设计．ＭＰＴ－Ｘ装置是进行托卡马克运行和多极器混合位形运行的装置,产生的磁场包括纵场、加热场、平衡场和八极场．各个磁场所采用的电源都是由储能电容器组、引燃管开关和线圈组成的ＲＬＣ放电回路．我们编制了一个通用程序,包括自感、互感和电阻的计算,电压和电流的波形计算,并附有绘图子程序,使用方便、快速．该程序适用于由多组轴对称线圈组成的放?...     

KDP晶体前表面修复轮廓的光强调制能力影响

在高功率激光系统中,精密微机械修复是减缓磷酸二氢钾（KDP）晶体表面缺陷增长的有效方法,使用精密微铣削机床可以加工出球面型与高斯型修复轮廓。为得到最优的修复结构参数,建立了晶体前表面球面型与高斯型修复轮廓的电磁场有限元模型,通过改变轮廓的宽度、深度等参数,对两种修复轮廓的光强调制能力进行对比研究。仿真结果表明光强调制能力主要是由修复轮廓的衍射效应及入射光在修复界面处的二次入射所引起的干涉作用共同决定;针对初始损伤点,建议采用宽深比大于5的修复轮廓,从而有效提高KDP晶体表面缺陷点的激光损伤阈值,对于宽深比大于10的修复轮廓建议选用高斯型;对宽1000 m,深20 m的两种修复表面的激光损伤实验表明,高斯型修复轮廓具有较高的抗损伤能力,实验与仿真结果相一致。     

基于改进的集合经验模态分解的爆破振动信号趋势项消除方法

针对实测爆破振动信号中存在的趋势项干扰问题,基于改进的集合经验模态分解,提出一种趋势项消除方法,并进行了模拟信号的仿真计算和爆破振动信号的实例分析.信号仿真计算结果显示:对于持续振动信号,该方法的趋势项提取结果与已有的基于经验模态分解或集合经验模态分解的趋势项消除方法较为接近;但当测试信号呈间歇振动时,该方法对趋势项的提取更为充分,体现了其对分段爆破振动信号中趋势项消除的优越性和适用性.同时,爆破振动速度信号的实例分析验证了该方法在实际应用过程中的可靠性.      

Mechanism of micro-waviness induced KH2PO4 crystal laser damage and the corresponding vibration source

The low laser induced damage threshold of the KH₂PO₄ crystal seriously restricts the output power of inertial confinement fusion. The micro-waviness on the KH₂PO₄ surface processed by single point diamond turning has a significant influence on the damage threshold. In this paper, the influence of micro-waviness on the damage threshold of the KH₂PO₄ crystal and the chief sources introducing the micro-waviness are analysed based on the combination of the Fourier modal theory and the power spectrum density method. Research results indicate that among the sub-wavinesses with different characteristic spatial frequencies there exists the most dangerous frequency which greatly reduces the damage threshold, although it may not occupy the largest proportion in the original surface. The experimental damage threshold is basically consistent with the theoretical calculation. For the processing parameters used, the leading frequency of micro-waviness which causes the damage threshold to decrease is between 350^-1 μ^-1 and 30^-1 μ^-1, especially between 90^-1 μ^-1 and 200^-1 μ^-1. Based on the classification study of the time frequencies of micro-waviness, we find that the axial vibration of the spindle is the chief source introducing the micro-waviness, nearly all the leading frequencies are related to the practical spindle frequency (about 6.68 Hz, 400 r/min) and a special middle frequency (between 1.029 Hz and 1.143 Hz).     

三七对血液、心脑血管和中枢神经系统的药理作用研究概述

综述了三七对血液、心脑血管和中枢神经系统的药理作用研究的发展现状。通过对有关文献资料进行分析、归纳和总结,发现三七不仅具有人们所熟知的止血、散瘀、消肿、止痛等功效,近年来更是在心脑血管疾病的治疗中发挥重要作用,对心肌缺血、脑缺血均有良好的保护作用,并用于治疗冠心病、心律失常等。三七的药用开发远未及其自身价值水平,有必要加强对三七的基础研究及加大三七用于医疗和保健品的开发力度。     

测地流、连接轨道和几乎完整叶层

研究T²上测地流的特殊动力学行为. 所给例子显示存在这样的保面积单调扭转映射, 它的所有极小周期轨之间有连接轨道, 并且某些有理旋转数的极小集几乎是一个不变圈.     

基于嵌入式系统的发射度测量仪

基于嵌入式系统的发射度测量仪采用法拉第筒测量方法,数据采样率达到200 kHz,设计有7个不同的电流采样量程。讨论了发射度测量仪的系统构成和工作原理,详细介绍了其数据采集系统的设计与制作。通过选用高速、低噪声的集成电路芯片并组合适当大小、适宜材料的电阻和电容构建模拟链路,贯穿于整个模拟链路的滤波设计和低噪声的模拟电源技术及屏蔽防护技术都保证了低噪声采集电路的实现。实验测试表明:在量程为10 nA时,该测量仪测量精度为1.47%,量程1 000 nA时则达到0.32%;采样20 kHz的正弦波信号失真度为6.5 dB;运动精度为1.25 m时,运动速度最高3.125 mm/s。