六类标准的颁布与网络的应用

六类布线测试标准的颁布会对网络的应用发展起很大的推动作用。文章对此进行了深入分析，提出了进行网络系统工程中应加考虑的几个方面。     

薄膜SOI材料MOSFET的高温泄漏电流

在对体硅MOSFET高温泄漏电流研究的基础上,深入研究了SOI材料MOSFET泄漏电流的组成、解析式及高温模拟结果,并与体硅MOSFET进行了比较,证明薄膜SOI材料MOSFET的高温泄漏电流明显减小,因而在高温领域中有着广阔的应用前景。     

有线宽带接入技术分析比较及其发展

介绍了目前宽带接入技术的发展概况,对主要的几种有线宽带接入技术如基于铜线的xDSL技术、基于HFC网的Cable Modem技术、基于五类线的以太网接入技术和基于无源光网络(PON, Passive Optical Network)的接入技术进行概述并作分析比较,最后讨论了有线宽带接入技术的发展.     

通过CNR实现Cable Modem MAC认证

基于Cable Modem的认证系统的开发一直相对滞后,这也相对制约了Cable Modem高级业务的发展.介绍了笔者对Cable Modem认证的一些新的思路及尝试,通过建立Cable Modem MAC认证弥补现有认证系统的不足.     

Fluid Flow-Induced Nonlinear Vibration of Suspended Cables

The nonlinear interaction of the first two in-plane modes of a suspended cable with a moving fluid along the plane of the cable is studied. The governing equations of motion for two-mode interaction are derived on the basis of a general continuum model. The interaction causes the modal differential equations of the cable to be non-self-adjoint. As the flow speed increases above a certain critical value, the cable experiences oscillatory motion similar to the flutter of aeroelastic structures. A co-ordinate transformation in terms of the transverse and stretching motions of the cable is introduced to reduce the two nonlinearly coupled differential equations into a linear ordinary differential equation governing the stretching motion, and a strongly nonlinear differential equation for the transverse motion. For small values of the gravity-to-stiffness ratio the dynamics of the cable is examined using a two-time-scale approach. Numerical integration of the modal equations shows that the cable experiences stretching oscillations only when the flow speed exceeds a certain level. Above this level both stretching and transverse motions take place. The influences of system parameters such as gravity-to-stiffness ratio and density ratio on the response characteristics are also reported.     

Integral formulation for a circular cylindrical cavity in infinite solid and a finite length coaxial cylindrical crack compressed axially

A method for solving problems of fracture of an infinite solid with a circular cylindrical cavity and a coaxial cylindrical crack near the surface under an uniform axial compression is proposed using a non-classical criterial approach associated with a mechanism of a local stability loss near the defect. The theory of integral Fourier transforms and series expansions are used to reduce these problems to a system of paired integral equations and then to a system of linear algebraic equations with respect to the contraction parameter.     

Robust PID control of fully-constrained cable driven parallel robots

In this paper dynamic analysis and robust PID control of fully-constrained cable driven parallel manipulators are studied in detail. Since in this class of manipulators cables should remain in tension for all maneuvers in their workspace, feedback control of such robots becomes more challenging than that of conventional parallel robots. In this paper, structured and unstructured uncertainties in dynamics of the robot are considered and a robust PID controller is proposed for the cable robot. To ensure that all cables remain in tension internal force concept is used in the proposed PID control algorithm. Then, robust stability of the closed-loop system with proposed control algorithm is analyzed through Lyapunov direct method and it is shown that by suitable selection of the PID controller gains, the closed-loop system would be robustly stable. Finally, the effectiveness of the proposed PID algorithm is examined through experiments on a planar cable driven robot and it is shown that the proposed control structure is able to provide suitable performance in practice.     

月表温度变化下电缆装联材料性能影响分析

在探月任务中,由于月球表面温度变化非常大,探测器上的电缆需要经历高温达125℃,低温达-180℃的严酷极限温度条件,因此电缆装联所用的电连接器、热缩套管、灌封胶等材料是否能经受住如此严酷的温度是一个疑问。为此开展了高低温下电缆用材料的特性变化试验,并对出现的问题进行了分析,得出了可适用于深空探测的合适的材料。试验结果如下:(1)airborn微小型电连接器在125℃高温下绝缘性能显著下降,国产J30JH微小型连接器高温绝缘性能较稳定;(2)125℃高温下国产RSG热缩套管发生熔化并粘连;(3)高低温循环作用下,采用ATUM套管加热缩带或纯热缩带的方式可保证尾罩处理满足使用要求。     

一种用于多径衰落水声信道的盲均衡算法研究

信道均衡是现今高速水声通信系统中克服码间干扰一项关键技术,如何提高均衡器的性能是目前研究的热点课题。针对水声信道的时变多普勒特性,在分析信道模型及盲均衡器结构特点的基础上,提出了一种时域解相关的变步长恒模算法,并对算法进行了仿真及试验分析。结果表明改进算法能够有效克服实际水声通信中的码间干扰效应,具有更快的收敛速度和更小的剩余误差,提高了浅海水声通信的有效性和可靠性,具有广阔的工程应用前景。