Energy-based robust controller design for flexible spacecraft

This paper presents a class of non-model2based position controllers for a kind of flexible spacecraft. With the controllers, one can achieve not only the closed-loop stability of the original distributed parameter system, but also the asymptotic stability of the truncated system, which is obtained through representing the deflection of the appendage by an arbitrary finite number of flexible modes. The system dynamics are not explicitly involved in the controller design and stability proof. Instead, only a very basic system energy rehtionship of the flexible spacecraft is utilized. The controllers possess several remarkable advantages over the traditional model-based ones. Numerical simulations are carried out on a kind of spacecraft with one flexible appendage and satisfactory results are obtained.     

火电厂多代理控制系统

针对火电厂非线性、多变量和多控制目标的特点,设计了一个火电厂多代理控制系统(PPMACS).在PP MACS中,前馈控制代理(FFCAs)采用神经模糊系统进行决策,反馈控制代理(FBCAs)采用基于遗传算法的模糊系统进行决策.优化任务分解代理(OTDAs)通过一个优化代理和一个分解代理来进行多目标优化分解PPMACS的任务.协调代理根据运行条件协调PPMACS的各个代理.仿真结果显示了火电厂多代理控制系统能够实现火电单元机组的多目标运行和大范围负荷跟踪.神经网络、模糊逻辑和遗传算法是PPMACS中的智能代理进行决策的有效工具.     

An automatic method for identifying appropriate gradient magnitude for 3D boundary detection of confocal image stacks

Gradients play an important role in 2D image processing. Many edge detection algorithms are gradient‐based. We are interested in 3D boundary detection which can be considered as an extension of 2D edge detection in 3D space. In this paper, an algorithm to automatically and quantitatively measure the suitability of gradient magnitudes in detection of 3D boundary points of confocal image stacks is presented. A Measurement Function is defined to evaluate the suitability of each gradient magnitude chosen to be the threshold for 3D boundary detection. The application of Gauss's Divergence Theorem provides a solution to calculate the Measurement Function numerically. The gradient magnitude at which the maximum of the Measurement Function is achieved can be utilized as the most appropriate threshold for gradient‐based boundary detection and other operations like volume visualization.     

Variable step-size affine projection algorithm based on global speech absence probability for adaptive feedbackcancellation简

A novel approach is proposed for improving adaptive feedback cancellation using a variable step-size affine projection algorithm（VSS-APA） based on global speech absence probability（GSAP）.The variable step-size of the proposed VSS-APA is adjusted according to the GSAP of the current frame.The weight vector of the adaptive filter is updated by the probability of the speech absence.The performance measure of acoustic feedback cancellation is evaluated using normalized misalignment.Experimental results demonstrate that the proposed approach has better performance than the normalized least mean square（NLMS） and the constant step-size affine projection algorithms.     

氧化镍薄膜气体传感器性能提升

本文的目的在于优化甲醛气体传感器.微型甲醛气体传感器设计是以石英玻璃当作基材,白金(Pt)被当作微型加热器电阻来加热感测层,并以氧化镍(NiO)薄膜作为感测层.当环境内有甲醛气体存在时,NiO薄膜层上导电度会增加,因而导致感测层电阻值降低.此微传感器,膜厚为0.34μm,在300℃反应时间只需6秒,灵敏度可达13.5 kΩ/ppb,最低侦测限度可以量测到40 ppb. 而本研究中针对不同的甲醛气体浓度,分别添加金当其催化剂、玻璃基材上共溅镀氧化镍与氧化铝、并比较有无指叉电极、改变基材温度…等,以提升其氧化镍薄膜感测性能.     

NEURAL NETWORK MODELING FOR ESTIMATION OF SCOUR DEPTH AROUND BRIDGE PIERS

It is essential to predict the scour depth around bridge piers for hydraulic engineers involved in the economical design of bridge pier foundation. Conventional investigations have long been of the opinion that empirical scour prediction equations based on laboratory data over predict scour depths. In this article, the Back-Propagation Neural Network (BPN) was applied to predict the scour depth in order to overcome the problem of exclusive and the nonlinear relationships. The observations obtained from thirteen states in USA was verified by the present model. From the comparison with conventional experimental methods, it can be found that the scour depth around bridge piers can be efficiently predicted using the BPN.     

基于GPU的Viterbi并行解码算法的设计与实现

针对GPU并行计算特征,对Viterbi解码自身做了并行处理探索,并提出使用Zero-Termination卷积码来实现基于GPU的Viterbi解码分块并行处理.设计的实现结果表明:Zero-Termination卷积码的简单而适用于GPU分块并行;误码率降低,特别是在信噪比低的情况下,Zero-Termination卷积码误码率比不损失码率的卷积码要低.同时,还实现了基于GPU的7,9,15三种不同约束长度的Viterbi解码,获得了良好的误码性能曲线及高吞吐率表现.     

Performance improvement using time delays in multivariable controller design

A new controller for linear multivariable ordinary systems is suggested in which distributed delays are included in the feedback loop. A general design approach to obtain this type of controller is suggested. It is shown that the resulting closed-loop system is asymptotically stable under some sufficient conditions. Sufficient conditions are derived under which the disturbance attenuation, the robustness against parameter variations, and the time-delay stability margins are improved by the proposed controller. The state feedback tracking controller and the dual-state observer are obtained by modification of the proposed controller.     

FROM ARTIFICIAL LIFE TO REAL LIFE: COMPUTER SIMULATION OF PLANT GROWTH∗

Artificial life is by itself an important area of scientific investigation. However, this scientific discipline will be more effective if it can also help one to understand how natural living systems really work. It is argued that plant growth is an area where the studies in artificial life lend themselves to computer modeling of what really happens in nature. An approach for such modeling is described, and the initial results of implementing this approach for a corn plant growth are presented.     

New results for the stability of uncertain time-delay systems

In this paper, based on the Lyapunov stability theorem associated with matrix measure techniques, some new delay-independent criteria for asymptotic stability of linear perturbed time-delay systems are proposed. Furthermore, the stability degree testing problem of the above systems is also investigated. From the given examples, we demonstrate the superiority of these quantitative results by comparing them with other approaches presented in the literature