无源高阶终端滑模控制双馈风力发电系统

为了简化双馈风力发电系统模型并且使得系统具有抗干扰的特性,依据无源性理论和滑模控制理论从能量和鲁棒性的角度研究了变速恒频双馈风力发电系统.首先建立了基于Euler La-grange (EL)方程的双馈风电系统数学模型,使得双馈风电系统分解为电气和机械两个无源子系统的反馈互联.在设计控制器时只需考虑电气子系统,而机械子系统是一个能量耗散系统,通过选择适合的参数可以保证稳定,因此简化了控制算法.针对速度环响应速度慢,鲁棒性差的问题设计了高阶非奇异滑模速度控制器.仿真结果表明了所提控制算法简单有效,能够保证风力发电系统输出恒定频率的同时,电机转速也能快速的跟踪参考转速,提高了整个系统的动静态性能.     

Aging of passive film on UNS N08031 in a Green-Death solution

Aging of passive film formed on UNS N08031 was investigated as a function of passivation time in Green-Death solution at 40°C. The specimen surface was in a stable passive state in the solution. The passive current density increased with an increase in the passivation potential. Electrochemical impedance spectroscopy and Mott–Schottky (M–S) analyses revealed that a more defective n-type semiconductive passive film formed as the potential increased while the film became stable as the defects in the film decreased at potential lower than 1.0?V_SSE. The increase of the applied potential and the polarisation time are likely reasons for the change in passive film stability.     

Passivity and synchronization of switched coupled reaction–diffusion neural networks with non-delayed and delayed couplings

ABSTRACT

This paper presents a general array model of switched coupled reaction–diffusion neural networks (CRDNNs) with non-delayed and delayed couplings. By utilizing some inequality techniques, we derive several sufficient conditions ensuring the input strict passivity and output strict passivity of the proposed network model. In addition, by constructing an appropriate Lyapunov functional, a sufficient condition is established in the form of linear matrix inequations to guarantee synchronization of CRDNNs with switched topology. Numerical examples with simulation results are provided to demonstrate the effectiveness and correctness of the obtained results.     

随机系统模型参考自适应控制

本文研究了随机系统的模型参考自适应控制问题，针对ＡＲＭＡＸ模型，给出了加权一步超前模型参考控制律及自适应控制律，且证明了自适应控制律的收敛性及闭环系统输入输出有界性。     

MANET中的高准确度地址冲突检测算法

基于被动地址检测算法PACMAN,找出其在部分网络环境下出现误判的原因,指出其不适用于可设定最佳路由标准的按需路由的缺陷。提出RPS算法,采用牺牲部分的网络流量和节点处理能力的方法,有效地解决PACMAN算法出现误判和部分路由算法不适用的情况。使用NS-2仿真工具对RPS与PACMAN算法进行模拟仿真对比,结果证明了RPS算法的改进效果。     

Passivity-based target manipulation inside a deformable object by a robotic system with noncollocated feedback

Target manipulation inside a deformable object by a robotic system is necessary in many medical and industrial applications. However, this is a challenging problem because of the difficulty of imposing the motion of the internal target point by a finite number actuation points located at the boundary of the deformable object. In this work, an optimal contact formulation and a control action are presented, in which a deformable object is externally manipulated with multiple robotic fingers such that an internal target point is positioned to a desired location. First, we formulate an optimization technique that minimizes the total force applied to the object to determine the location of actuation points to affect the desired motion. Then, a passivity-based control approach, based on energy monitoring and dissipation, is developed to improve stability of the whole system. The simulation results demonstrate the efficacy of the proposed method.     

A reduction technique of large‐scale RCG interconnects in the complex frequency domain

High‐speed digital LSI chips usually consist of many sub‐circuits coupled with multi‐conductor interconnects embedded in the substrate. They sometimes cause serious problems of the fault switching operations due to the time‐delays, crosstalks, reflections, etc. In order to solve these problems, it is very important to develop a user‐friendly simulator for the analysis of LSIs coupled with interconnects. In this paper, we consider a large‐scale gate‐array circuit coupled with multi‐conductor RCG interconnects. At first, we propose a new method for calculating the dominant poles of the impedance matrix, which give the large effects to the transient response. The corresponding residues are estimated by the least squares method. Using these poles and residues, the input–output relation of each interconnect can be described by the partial fractions. After then, the interconnect is replaced by the equivalent circuit realizing the partial fractions. In this way, we can easily develop a user‐friendly simulator familiar with SPICE. We found from many examples that the good results can be obtained using only few dominant poles around the origin. Furthermore, the reduction ratio of our method is very large especially for large scale interconnects. Copyright © 2004 John Wiley & Sons, Ltd.     

试论应用写作主体的思维特征

立足于写作学研究实际，运用实证研究和归纳推理等方法，针对应用写作主体的思维，结合具体实例，通过与文学写作的比较，总结、归纳出目的性、被动性、明确性、客观性、逻辑性、模式性等六个方面的特征。