Web软件的易用性测试探究

随着网络技术在软件方面的广泛应用,Web软件以其方便、快速、易操作等特点成为软件开发的重点。作为与用户交互的主要特性,易用性也随之成为Web软件关注的热点,而易用性测试也为越来越多的人所重视。根据Web软件的特点,对Web软件的易用性测试标准、如何进行Web软件易用性测试以及易用性测试的具体操作步骤进行了探讨。     

Output feedback stabilization for time-delay nonlinear interconnected systems using neural networks.

In this paper, dynamic output feedback control problem is investigated for a class of nonlinear interconnected systems with time delays. Decentralized observer independent of the time delays is first designed. Then, we employ the bounds information of uncertain interconnections to construct the decentralized output feedback controller via backstepping design method. Based on Lyapunov stability theory, we show that the designed controller can render the closed-loop system asymptotically stable with the help of the changing supplying function idea. Furthermore, the corresponding decentralized control problem is considered under the case that the bounds of uncertain interconnections are not precisely known. By employing the neural network approximation theory, we construct the neural network output feedback controller with corresponding adaptive law. The resulting closed-loop system is stable in the sense of semiglobal boundedness. The observers and controllers constructed in this paper are independent of the time delays. Finally, simulations are done to verify the effectiveness of the theoretic results obtained.     

Robust H∞ control of uncertain linear impulsive stochastic systems

This paper develops robust stability theorems and robust H_∞ control theory for uncertain impulsive stochastic systems. The parametric uncertainties are assumed to be time varying and norm bounded. Impulsive stochastic systems can be divided into three cases, namely, the systems with stable/stabilizable continuous‐time stochastic dynamics and unstable/unstabilizable discrete‐time dynamics, the systems with unstable/unstabilizable continuous dynamics and stable/stabilizable discrete‐time dynamics, and the systems in which both the continuous‐time stochastic dynamics and the discrete‐time dynamics are stable/stabilizable. Sufficient conditions for robust exponential stability and robust stabilization for uncertain impulsive stochastic systems are derived in terms of an average dwell‐time condition. Then, a linear matrix inequality‐based approach to the design of a robust H_∞ controller for each system is presented. Finally, the numerical examples are provided to demonstrate the effectiveness of the proposed approach. Copyright © 2007 John Wiley & Sons, Ltd.     

RBF和PIDNN在伺服电机模型中的应用比较

为了更好地发挥RBF和PIDNN神经网络的优势,通过对伺服电机模型辨识和控制问题的分析,对RBF和PIDNN网络的应用效果进行了仿真实验的对比研究。结果表明,RBF神经网络结构复杂,参数难以调整,但具有最佳一致逼近能力,辨识效果优于PIDNN;PIDNN结构简单,比例元、积分元和微分元具有类似PID的控制作用,控制效果优于RBF。     

Video Annotation Based on Kernel Linear Neighborhood Propagation

The insufficiency of labeled training data for representing the distribution of the entire dataset is a major obstacle in automatic semantic annotation of large-scale video database. Semi-supervised learning algorithms, which attempt to learn from both labeled and unlabeled data, are promising to solve this problem. In this paper, a novel graph-based semi-supervised learning method named kernel linear neighborhood propagation (KLNP) is proposed and applied to video annotation. This approach combines the consistency assumption, which is the basic assumption in semi-supervised learning, and the local linear embedding (LLE) method in a nonlinear kernel-mapped space. KLNP improves a recently proposed method linear neighborhood propagation (LNP) by tackling the limitation of its local linear assumption on the distribution of semantics. Experiments conducted on the TRECVID data set demonstrate that this approach outperforms other popular graph-based semi-supervised learning methods for video semantic annotation.     

Cross-Layer Optimization for State Update in Mobile Gaming

In a large-scale mobile gaming environment with limited wireless network bandwidth, efficient mechanisms for state update are crucial to allow graceful real-time interaction for a large number of players. By using the state updating threshold as a key parameter that bridges the resulting state distortion and the network traffic, we are able to study the fundamental traffic-distortion tradeoffs via both theoretical modeling and numerical analysis using real game traces. We consider a WiMAX link model, where the bandwidth allocation is driven by the underlying physical layer link quality as well as application layer gaming behaviors. Such a cross-layer optimization problem can be solved using standard convex programming techniques. By exploring the temporal locality of gaming behavior, we also propose a prediction method for on-line bandwidth adaptation. Using real data traces from a multiplayer driving game, TORCS, the proposed network-aware bandwidth allocation method (NABA) is able to achieve significant reduction in state distortion compared to two baselines: uniform and proportional policies.     

A corner differentiation algorithm by a single sonar sensor for mobile robots

Ultrasonic sensors have been widely applied in mobile robots to obtain environmental information and avoid obstacles. In general, a typical domestic environment consists of planes, edges and corners. It is usually difficult to distinguish a plane from a corner directly with a single ultrasonic sensor. To overcome this difficulty, a corner differentiation algorithm for a single ultrasonic sensor is proposed in this paper. The algorithm is based on the features of all of the actual reflection points from the environment obtained by a reflection search algorithm from which the corners are realized by a corner differentiation algorithm. The experimental results show that the developed algorithm can successfully detect all planes and corners. Furthermore, an environmental map can be built based on the information obtained on planes and corners. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

国内外信息安全管理体系研究

该文对国内外主流的信息安全管理体系进行了梳理和研究,对不同体系的框架和内容进行探讨,为企业选择和建立适合的、完善的信息安全管理体系提供有意义的借鉴。     

高效好氧生物技术及其在污水处理中的应用

近年来好氧生物技术得到了不断的发展,出现许多高效的、可处理难降解甚至有毒废水的好氧生物技术。本文主要综述了3种从不同方面实现高效降解有机废水的好氧生物处理技术:移动床生物膜反应器、加压曝气技术以及膜生物反应器在废水处理中的应用进展,并概括了各自的优缺点,最后对这3种生物工艺的发展进行了展望。     

基于P-FUZZY-PID的飞行器大角度机动控制物理仿真

针对空间飞行器大角度姿态机动控制具有非线性,并要求控制器具有较高的指向精度、姿态稳定度及鲁棒性等特点,应用P-FUZZY-PID复合控制算法,建立了±180°内的模糊规则库,设计了飞行器姿态控制器;系统采用DSP作为星载控制器,光纤陀螺作为姿态敏感器,反作用飞轮作为执行机构,系统程序采用C语言编程,利用单轴气浮仿真实验台实现了物理仿真实验;实验结果证明该控制方法不仅能实现飞行器大角度机动控制,机动响应快,还表现出较好的鲁棒性。