基于加权LS-SVM的飞行事故率预测模型

飞行事故率是表征飞行安全水平的重要指标,其预测是典型的小样本问题。针对飞行事故率预测建模难的问题,采用加权LS-SVM方法,建立了飞行事故率的时间序列预测模型。仿真实验表明,加权LS-SVM具有很高的建模精度和较强的泛化能力,从而验证了该方法的有效性和先进性。     

太赫兹技术在室内无线通信中的应用

该文通过对太赫兹通信相关器件的总结和相关信道特性的分析,调研了近年来国内外相关实验的结果,对重点实验结果做了着重描述,总结出了未来室内无线通信可能的发展方向和亟待解决的问题。太赫兹波段是介于毫米波与远红外的电磁辐射频段。室内无线局域网的高数据率传输要求通信系统运行于更高的频率以获得更大的带宽。太赫兹频率范围未受军事管制,可实现Gbit/s数据率,并且太赫兹频域不像光频受环境噪声干扰那么严重。全固态室温太赫兹器件的研究为太赫兹无线通信系统奠定了基础。已探明适于未来太赫兹室内通信系统运行的大气窗口。基于飞秒激光门控光导天线的太赫兹通信链路实现了太赫兹波载波音频信号的调制和解调。     

Nonsingular fast terminal sliding‐mode control for nonlinear dynamical systems

This paper investigates fast finite‐time control of nonlinear dynamics using terminal sliding‐mode (TSM) scheme. Some new norms of fast TSM strategies are proposed, and a faster convergence rate is established in comparison with the conventional fast TSM. A novel concept of nonsingular fast TSM, which is able to avoid the possible singularity during the control phase, is adopted in the robust high‐precision control of uncertain nonlinear systems. Numerical simulation on a two‐link rigid robot manipulator demonstrates the effectiveness of the proposed algorithm. Copyright © 2010 John Wiley & Sons, Ltd.     

A reduction method of dynamic false contour utilizing the frame‐rate‐control method with suppression of the side effect on PDPs

Abstract— The plasma‐display panel (PDP) is a type of flat‐panel display that can display a high‐quality image. However, when moving images are displayed, annoying disturbances such as false contour noise occurs. This noise is called dynamic false contour (DFC). To achieve a higher‐quality image, DFC has to be reduced. Therefore, a new method to reduce DFC is proposed. To find a way to reduce DFC, a new evaluation value for it has been defined: the evaluation value of dynamic false contour (EVDFC). This value is defined on the basis of a person's subjective evaluation. By applying this value, the cause that generates DFC can be identified. On the basis of these studies, a new method for reducing DFC by applying frame‐rate control (FRC) with suppression of the side effect is proposed. This improved method can be used to provide high‐quality images.     

Multi‐response optimization and empirical modeling of cardiopulmonary responses during manual lifting tasks

An experimental study involving five independent lifting variables (namely weight, lift frequency, horizontal distance from the object, operator, and vertical distance) and their interactions was conducted using the Taguchi L₂₇ design. Two responses—heart rate and oxygen uptake—were measured during each trial. To optimize both responses simultaneously, the signal‐to‐noise ratio was normalized to obtain a multi‐response signal‐to‐noise (MRSN) ratio for each trial. The MRSN ratio was analyzed using analysis of variance to identify the optimal condition in which both responses were optimized at the same time. Lift frequency was found to be the most significant factor, and operator and horizontal distance were found to be least significant. The empirical modeling equation was developed and can be used to predict the response values during experimental trials involving similar work conditions. © 2010 Wiley Periodicals, Inc.     

管道泄漏监测的传感器网络中数据存取算法实现

针对管道泄漏和管网突发性的爆管,将自适应数据存取设计应用于管道流量泄漏监测中,数据存取是指生产者将感知数据按照策略存放在特定的位置上,消费者将查询请求按照对应策略路由到数据存放位置获得感兴趣的数据.首先依据生产者和消费者关系建模"一对一"、"多对一"、"多对多"模型来对存取代价进行分析.其次确定数据存放位置的自适应全局最优贪婪算法ODS和局部最优近似算法NDS以及最优数据传输模式.最后ODS和NDS通过自适应调整来减少数据存取能量消耗.实验表明NDS不仅节省能耗,而且在70%的情况下达到与ODS相同的效果.     

基于H.264码率控制的模型参数更新算法

为获得精确的模型参数,从率点选择和模型参数估计2个方面对H.264码率控制算法加以改进,利用一种基于曼哈顿和二维滑动窗口机制相结合的策略,实现高效的率点选择算法,采用加权的线性回归技术,实现有效的模型参数预测。实验结果表明,改进后的算法能改善视频编码质量,提高输出码率的控制精度。     

FRA:基于帧长和发送速率的信道竞争算法

提出一种MAC层竞争信道的FRA算法。FRA算法以实验测得的数据帧长和信道速率作为调节CWmin的因子,提高了发送大数据帧或高速信道节点的信道占用时间。实验结果表明,该算法在速率、帧长各异的无线网络环境中,网络总吞吐率比DCF协议提高约70%。     

基于双向运动补偿的帧速率上变换算法

针对不同帧速率视频之间的转换问题,提出一种改进的基于双向运动补偿的帧频提升算法,通过边缘加权获取高精度的双向运动向量,利用可变尺寸块运动向量场估计逐级对运动向量求精,采取自适应重叠块补偿方法解决帧频提升过程中产生的重叠及空洞问题,提高双向运动向量的精度,减小块效应。实验结果表明,与传统的帧频提升算法相比,该算法在内插图像主、客观质量方面都有较大提升。     

WSNs覆盖的拟物力导向粒子群优化策略

针对无线传感器网络的重复覆盖和算法耗时问题,提出一种拟物力导向的粒子群覆盖优化策略。通过仿真实验对该策略进行优化性能测试,与粒子群算法、粒子进化的多粒子群算法、传统遗传算法和新量子遗传算法的优化效果相比,该策略覆盖率分别提高9.5%、1.7%、6.03%和3.71%,收敛速度分别提高23.2%、1.8%、24.5%和24.5%。结果表明该优化策略具有比上述4种算法更好的覆盖优化效果。