昂科雷汽车音响虚假静音分析

一辆别克进口SUV昂科雷的车主反映:新车刚提回去没有几天音响就不响了,不论收音机还是CD都不发声,音量调节无效,同时该车也没有单独操作的"MUTE"静音按键,但现象就像"静音",已在多家品牌店维修,故障未能有效排除。     

Simulation of Chaos in Asymmetric Nonlinear Chua＇s Circuit

In order to describe practical chaotic systems exactly, we presented a simple modified Chua's circuit,which contains an asymmetric nonlinear resistive element. Mathematical analysis was made, and simulation study was performed by MATLAB. By varying the value of linear resistor in the circuit, rich variety dynamical behaviors were observed, such as DC equilibrium point, Hopf bifurcation, period-doubling bifurcation,single-scroll strange attractor, periodic windows, and asymmetric double-scroll strange attractor. The extreme sensitivity in the state trajectory with respect to the initial conditions was exhibited; the special characteristic of asymmetric nonlinear Chua's circuit was found also.     

基于力与力矩补偿的挖泥船动力定位反步法控制研究

针对挖泥船工作过程中受强干扰的特点,提出了基于力、力矩前馈补偿与非线性反步法控制结合的挖泥船动力定位控制.力和力矩传感器前馈补偿挖泥船工作过程的反作用力,反步法闭环控制保证在补偿误差及其它干扰作用下使系统的全局渐近稳定,输出渐近跟踪设定位置.仿真结果表明,设计的挖泥船动力定位控制器具有良好的跟踪性能,并对挖泥强干扰有较好的鲁棒性.     

公路工程监理存在的主要问题浅析

公路工程监理制度,以国际通用的FIDIC合同条件为基础,形成了业主,承包商,监理单位三方相互制约,以监理单位为核心的模式,监理工程师对一项工程实施监理主要包括工程进度监理、工程质量监理、工程费用监理三大部分。在项目的建设中监理单位作为参建单位之一,对工程的质量起到控制的作用,是质量管理工作的核心,因此建设项目的好坏,监理工作质量水平是关键,必须高度重视监理工作。加强对监理单位的管理。但目前我省公路工程监理的存在以下主要问题。     

Bias current influence on the characteristic of the magnetic-controlled switcher type fault current limiter

A novel magnetic-controlled switcher type fault current limiter (FCL) for high voltage electric network is presented. The current limiting principle of the FCL and the bias current influence on the characteristic of the FCL are discussed. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively. Under the normal state, the bias current adjustment can change the FCL voltage loss; under the fault state, the steady fault current can be easily adjusted to the preset level by bias current regulating. The experimental result is in accordance with the principle analysis and the FCL has the advantages of flexible control strategy and simple and reliable structure. Foundation item: the National Basic Research Program (973) of China (No. 2005CB221505) and the Research Fund for Doctoral Program of High Education of China (No. 20050248058)     

Multiple models direct adaptive controller for a stochastic non-minimum phase system

For a stochastic non-minimum phase multivariable system, a multiple models direct adaptive controller is presented. It is composed of multiple fixed models with two adaptive models. The fixed models are used to cover the region where the system parameters jump and improve the transient response, while another two adaptive models are used to guarantee the stability. Utilizing generalized minimum variance design method, it adopts the stochastic system estimation algorithm with optimal controller design method to identify the controller parameter directly. Finally, the global convergence is given. The simulation proves the effectives of the controller proposed.     

通讯电源近场磁耦合干扰的诊断和抑制

开关电源主电路产生的强杂散电磁场会耦合到EMI滤波器上,会降低滤波器的衰减性能,导致电源传导干扰发射异常.提出"引线移位"调试方法,来迅速辨识电源中主要的磁场源和敏感体.考察了通讯电源输出滤波电感杂散磁场的特性和电源EMI滤波器共模电感的磁场敏感性,建立了反映磁场耦合效应的开关电源差模传导干扰基本模型模型.根据磁耦合机理,提出了几种改善电源的差模干扰发射的措施,并进行了验证.