异结构混沌系统的自适应函数投影同步及参数辨识

研究了异结构混沌系统的自适应函数投影同步及未知参数的辨识问题.基于Lyapunov稳定性定理和自适应控制技术,构造了自适应控制器和系统未知参数的辨识法则,实现了异结构混沌系统的自适应函数投影同步.以著名的Lorenz系统和Lü系统为例进行了数值仿真,仿真的结果表明所构造的自适应控制器的有效性和系统未知参数辨识法则的正确性.     

基于Colpitts振荡器的超宽带混沌雷达测距实验研究

实验研究了基于Colpitts振荡器的超宽带混沌雷达系统的测距性能。该系统利用改进型Colpitts振荡器产生自相关曲线主峰半高全宽(full width at half maximum,FWHM)为0.5ns的混沌信号,可提供7.5cm的距离分辨率;用混沌相关法对回波信号与参考信号进行处理,可获得目标距离信息。实验分析了在自由空间和存在障碍物情况下系统对单目标的测距性能,并用后向投影(back-projection,BP)算法对空间中目标进行了扫描成像。实验结果表明:该系统具有穿透探测的能力,可以实现厘米级的高精度测距;通过合成孔径技术,可以实现二维成像。     

关于混沌洛伦兹系统和陈系统中的广义投影同步

1 Introduction Since Pecora and Carroll[1]showed that it is possibleto synchronize two identical chaotic systems , chaossynchronization has been intensively and extensivelystudied due to its potential applications in secure com-munication,ecological systems ,systemidentification,etc.(see [2] and a huge volume of references citedtherein) . Among all kinds of chaos synchronizations ,projec-tive synchronization is one of the most noticeableones .This kind of synchronization was first observedin …     

基于自适应控制的混沌系统分时同步

讨论混沌系统的分时同步.通过设计控制策略实现了一个混沌系统的一个分量对另一个混沌系统的任一分量的分时跟踪同步,并且在同步的过程中,系统的参数也被识别.最后仿真结果表明了该方法的有效性.     

Application of chaotic theory to parameter estimation

High precision parameter estimation is very important for control system design and compensation. This paper utilizes the properties of chaotic system for parameter estimation. Theoretical analysis and experimental results indicated that this method has extremely high sensitivity and resolving power. The most important contribution of this paper is apart from the traditional engineering viewpoint and actualizing parameter estimation just based on unstable chaotic systems. Project supported by the National Science Foundation of China (Nos. 59975082 and 69675020).     

混沌保密通信实验电路设计

介绍了电路原理实验课的一个模块化、开放式的综合实验.在蔡氏电路的基础上,对部分功能模块进行了一定的改进,利用模拟电感代替真实电感,并在电感支路上增加RC并联结构,以此设计出性能相当稳定的混沌信号发生电路.通过简单电路和听音实验对混沌保密通信进行了原理上的研究.     

线性时变参量电路分析法

从时变参量元件及电路的定义出发,分析研究了属于电阻性电路形式的时变跨导电路,模拟乘法器电路,开关函数的三种线性时变参量分析法.     

Exponential synchronization of general chaotic delayed neural networks via hybrid feedback

This paper investigates the exponential synchronization problem of some chaotic delayed neural networks based on the proposed general neural network model, which is the interconnection of a linear delayed dynamic system and a bounded static nonlinear operator, and covers several well-known neural networks, such as Hopfield neural networks, cellular neural networks （CNNs）, bidirectional associative memory （BAM） networks, recurrent multilayer perceptrons （RMLPs）. By virtue of Lyapunov- Krasovskii stability theory and linear matrix inequality （LMI） technique, some exponential synchronization criteria are derived. Using the drive-response concept, hybrid feedback controllers are designed to synchronize two identical chaotic neural networks based on those synchronization criteria. Finally, detailed comparisons with existing results are made and numerical simulations are carried out to demonstrate the effectiveness of the established synchronization laws.     

杜芬系统参数对混沌信号频带宽度的影响

本文分析了杜芬系统参数对混沌信号频谱的影响,对混沌掩盖通信中混沌信号不能很好掩盖信息信号的问题进行了针对性的研究.仿真结果表明,通过调节杜芬系统参数和外加激励的频率可以达到扩展混沌信号带宽的目的.     

掺铒光纤激光器混沌同步实验研究

激光混沌信号的宽带、随机和不可预测性,使其具有天然的屏蔽性和保密能力,成为保密通信的优选光源。混沌同步作为混沌通信的基础,是混沌通信的研究热点。基于长腔的混沌光纤激光器,实验研究掺铒光纤放大器输出的混沌激光与光纤激光器的同步特性。结果表明：通过改变偏振控制器和泵浦电流,混沌光纤激光器与掺铒放大器在很大的范围内具有同步特性。     

Cognitive distortions and blame attribution in sex offenders against adults and children

OBJECTIVE: Sexual offenders tend to hold attitudes and beliefs which minimize and justify their offending behavior. It was hypothesized that distorted thinking supporting sexual offending and blame attribution would differ depending on the offence characteristics of different groups of sexual offenders. METHOD: Two groups of sexual offenders separated on the basis of the age of their victims (sex offenders against children, 36; sex offenders against adults, 30) were compared on measures of cognitive distortions relating to sex with children and rape and a measure of blame attribution which assesses external, mental element, and guilt feeling attributions. RESULTS: Child sexual offenders endorsed more cognitive distortions relating to sex with children, but there were no group differences in cognitive distortions relating to rape. Those who offended against adults reported more external attributions and child offenders reported more guilt feeling attributions. Mental element attribution related to alcohol intoxication and use of violence in the offence, but was not related to group differences. CONCLUSIONS: Results are interpreted as suggesting that child sex offenders support their offending by more enduring distorted cognitions, while those who offend against adults use blame attributions associated with the particular offence.     

Sliding mode control for synchronization of chaotic systems with structure or parameters mismatching

INTRODUCTION Synchronization of chaotic systems and its ap-plication to secure communication has recently re-ceived much attention. Several chaos synchronization schemes have been successfully established (Liao and Huang, 1999; Jiang, 2002; Zhao et al., 2004). How-ever, to our best knowledge, most of the chaos syn-chronization strategies have been studied in similar oscillators. In fact, from the perspective of hardware implementation, the resistance and capacitance of the resistors and…     

阻抗△与Y接法参数变换的推算

对于阻抗△与Y接法,采用了不同的推导方法,推出了参数变换公式,力图对不同的教学对象采用不同的教学方法,以加深阻抗三种接法换算公式和等效条件的理解.     

会计信息失真的成因及治理对策

会计信息综合反映单位一定时期的经营活动和经营成果,在改善微观管理和宏观调控方面发挥着重要作用。由于我国正处于经济体制的转轨时期,现代企业制度尚未真正建立,会计法制尚不健全等原因,会计信息失真问题比较严重。面对会计信息失真的现状、表现、危害、原因,从进一步完善公司治理结构、完善会计制度、加强会计法规建设、强化监督管理、提高会计人员素质等方面提出一些建议。     

基于导频和变换域的SISO/MIMO OFDM系统自适应信道估计

根据导频信号在变换域中的频响特性,将系统的变换域滤波器设计成具有更好滤波效果的"带阻滤波器";在小信噪比和大信噪比条件下,分析了变换域能量参数对系统信道估计性能的影响,推导了新的能量参数表达式,理论证明了根据接收端检测到的信噪比自适应选择能量参数可以显著改善信道估计的性能.仿真结果表明,提出的信道估计算法具有较好的性能,在一定程度上可以接近于理想信道估计的性能,适用于SISO OFDM系统和MIMO OFDM系统.     

Education and skill mismatches among immigrants: The impact of host language proficiency

This paper asks to what extent host language proficiency can insure immigrants against the risk of ending up in mismatched jobs. Using the 2003-2016 waves of the Household, Income and Labour Dynamics in Australia (HILDA), the paper discriminates between three forms of mismatch, overqualification, underqualification and overskilling. Host language proficiency is instrumented using Bleakley and Chin (Rev Econ Stat 86:481–496, 2004) strategy, which exploits the fact that younger children learn languages more easily than older ones. To differentiate between local average treatment effects (LATE) and average treatment effects (ATE), the paper considers two alternative models, 2SLS instrumental variables and biprobit. We find that treatment effects are heterogeneous. English language proficiency among immigrants in Australia reduces the probability of ending up in overqualified jobs, by between 17.2 (LATE) and 36.7 (ATE) percentage points. The ATE of overskilling is also significant and about -8.9 percentage points. In contrast, language skills tend to raise the probability of being underqualified at the job, by approximately 8.6 percentage points according to the ATE. Local effects of overskilling and underqualification fail to be statistically significant, suggesting that host language proficiency may be innocuous for some workers. Overall, the results indicate that host language proficiency is a country-specific, valuable form of human capital.     

混沌振动工程应用现状综述

概述了混沌现象以及混沌研究的意义,探讨了通向混沌的道路和混沌在工程方面的应用,并展望了它们的发展前景。     

通用载波同步系统设计与实现

设计并实现了一种基于现场可编门陈列的通用中频载波同步系统。该系统通过控制器对载波中心频率以及低通、带通、环路滤波器的系数等参数进行设置即可实现较宽频率范围内的正交和非正交方式下的载波同步。通过软件仿真与实际测试,验证了设计的正确性和可靠性。     

基于Proteus的555级联电路的仿真及频率计算

分析了救护车报警电路和555定时器的工作原理,用Proteus组合555芯片、电阻、电容对救护车报警电路进行了仿真,并将其仿真波形在同一屏幕上呈现出来,计算了其频率,计算结果与仿真结果一致.