基于微分几何方法的永磁同步电动机的混沌运动的控制

永磁同步电动机(PMSM)在某些参数及工作条件下会出现混沌运动，这将危及电机传动系统的稳定运行，因此如何抑制或消除PMSM中的混沌成为保持其稳定性的关键问题.利用微分几何控制理论，首先从解析上推导出PMSM混沌运动控制律的表达式，然后对控制过程进行仿真.理论分析及数值仿真结果表明：该控制策略不仅行之有效，而且相对其他控制方法具有一定的优越性.研究结果对保证电机传动系统的稳定运行具有较好的参考价值. 关键词： 混沌控制 微分几何 准确线性化 永磁同步电动机     

Identification of denatured and normal biological tissues based on compressed sensing and refined composite multi-scale fuzzy entropy during high intensity focused ultrasound treatment

In high intensity focused ultrasound(HIFU)treatment,it is crucial to accurately identify denatured and normal biological tissues.In this paper,a novel method based on compressed sensing(CS)and refined composite multi-scale fuzzy entropy(RCMFE)is proposed.First,CS is used to denoise the HIFU echo signals.Then the multi-scale fuzzy entropy(MFE)and RCMFE of the denoised HIFU echo signals are calculated.This study analyzed 90 cases of HIFU echo signals,including 45 cases in normal status and 45 cases in denatured status,and the results show that although both MFE and RCMFE can be used to identify denatured tissues,the intra-class distance of RCMFE on each scale factor is smaller than MFE,and the inter-class distance is larger than MFE.Compared with MFE,RCMFE can calculate the complexity of the signal more accurately and improve the stability,compactness,and separability.When RCMFE is selected as the characteristic parameter,the RCMFE difference between denatured and normal biological tissues is more evident than that of MFE,which helps doctors evaluate the treatment effect more accurately.When the scale factor is selected as 16,the best distinguishing effect can be obtained.     

珠江三角洲地区居民参与休闲体育活动的现状调查

运用文献资料、问卷调查、数理统计等方法,对珠江三角洲地区居民参与休闲体育活动的现状进行调查分析。结果显示,珠三角地区居民健康观念较强,休闲体育是大众居民在闲暇时间内最主要的休闲方式;运动场地、闲暇时间、健身指导员等是影响该地区居民从事休闲锻炼的重要因素。通过调查与分析,旨在为满足不同群体的体育健身与休闲消费需求,提高广大居民生命质量。     

大学物理实验教学模式改革探索与研究

大学物理实验教学模式改革的目标是紧密围绕课程培养方案,坚持"以学生为中心",通过"互联网+"技术,改革课堂教学模式和教学方法,提高课程的整体质量和教学水平.通过将传统的课堂教学模式与慕课堂、翻转课堂、线上线下混合式教学、虚拟仿真等新型教学模式相结合,使之适应现代化高等教育的需求,成为能够对学生核心素质提升和专业能力培养具有重大影响的"有用的"课程.     

概率方法在布尔函数相关免疫性研究中的应用

本文揭示了布尔函数的Ｗａｌｓｈ谱及“相关度”的概率实质，证明了Ｗａｌｓｈ谱的两条重要性质，正确地揭示了多维布尔向量函数的相关免疫性与其各分量的相关免疫性之间的关系；定义了布尔向量函数的Ｗａｌｓｈ变换及Ｗａｌｓｈ谱，并由此给出了与Ｘｉａｏ－Ｍａｓｓｅｙ定理相应的判别条件。     

Controlling chaos in permanent magnet synchronous motor based on finite-time stability theory

This paper reports that the performance of permanent magnet synchronous motor (PMSM) degrades due to chaos when its systemic parameters fall into a certain area. To control the undesirable chaos in PMSM, a nonlinear controller, which is simple and easy to be constructed, is presented to achieve finite-time chaos control based on the finite-time stability theory. Computer simulation results show that the proposed controller is very effective. The obtained results may help to maintain the industrial servo driven system's security operation.     

用BP神经网络模型评价养殖区水域的富营养化——以湖州地区为例

根据养殖区水域富营养化程度主要影响因素和评价标准,用足够多的BP神经网络训练样本、检验样本和测试样本进行模拟学习,给出了区分养殖区富营养化程度的分界值,能够直观地进行不同等级富营养化程度的划分.所得到的神经网络模型具有较好的泛化能力和预测能力,减少了人为主观因素的影响,该模型有一定的客观性、通用性和实用性.实例分析表明,湖州地区养殖区外荡水域富营养化程度比较严重,处于富营养化和重富营养化状态.     

浅析双流县水资源现状及保护

本文通过对双流县地表水和地下水资源的水量和水质两方面的整体考虑，对双流县水资源的利用和保护提出了相关建议以及切实可行的措施方法。