A novel criterion for cluster synchronization of complex dynamical networks with coupling time-varying delays

This paper investigates the cluster synchronization problem for the time-varying delays coupling networks with nonidentical delayed dynamical systems by using pinning control method. We derive some simple and useful criteria for cluster synchronization for any initial values through an effective feedback control scheme and propose an adaptive feedback strategy that adjusts automatically the coupling strength. Finally, some numerical examples are then given to illustrate the theoretical results.     

n型主动拉曼增益原子介质中的光学双稳态

研究了主动拉曼增益原子介质在单向环形腔中的光学双稳态．该系统是一个相干共振的n型四能级原子系统,可在室温下实现,有能级失谐量、原子数密度、抽运场、控制场等较多的可调参数,且有无增益的透明窗口．完全通过解析方法定量给出实现光学双稳态的条件,以及可调参数的取值范围,并进一步给出实现光学多稳态的条件,为实验上实现光学双稳态与多稳态提供了理论依据．     

微波消解电感耦合等离子体-质谱法测定面粉中的铝

面粉样品经微波消解后,以⁴⁵Sc为内标元素校准基体效应及信号漂移,用电感耦合等离子体.质谱法直接测定,外标法绘制校准曲线进行定量。测定面粉中铝的检出限为0.25mg/kg,线性良好,相关系数r=0.9999,相对标准偏差1.25%—3.03%,加标回收率在93.9%—103.5%之间。该方法灵敏快速,干扰小,重现性好,能满足面粉中铝含量测定的要求。     

Adaptive sliding mode control of dynamic system using RBF neural network

This paper presents a robust adaptive sliding mode control strategy using radial basis function (RBF) neural network (NN) for a class of time varying system in the presence of model uncertainties and external disturbance. Adaptive RBF neural network controller that can learn the unknown upper bound of model uncertainties and external disturbances is incorporated into the adaptive sliding mode control system in the same Lyapunov framework. The proposed adaptive sliding mode controller can on line update the estimates of system dynamics. The asymptotical stability of the closed-loop system, the convergence of the neural network weight-updating process, and the boundedness of the neural network weight estimation errors can be strictly guaranteed. Numerical simulation for a MEMS triaxial angular velocity sensor is investigated to verify the effectiveness of the proposed adaptive RBF sliding mode control scheme.     

杂环化合物的烯丙基化和苄基化反应的研究概况

分子中含O、S和N的杂环化合物,如呋喃、噻吩、吡咯和吲哚等及其衍生物是许多天然产物的活性成分,也是功能材料的重要构件。 因此,开展杂环化合物简便高效的官能化反应的研究显得尤为重要。 其中杂环化合物的烯丙基与苄基化反应是最具有吸引力的杂环官能团化反应之一。 本文综述了杂环化合物的烯丙基化和苄基化反应的研究进展。     

Pseudopotential multi-relaxation-time lattice Boltzmann model for cavitation bubble collapse with high density ratio

The dynamics of the cavitation bubble collapse is a fundamental issue for the bubble collapse application and prevention. In the present work, the modified forcing scheme for the pseudopotential multi-relaxation-time lattice Boltzmann model developed by Li Q et al. [ Li Q, Luo K H and Li X J 2013 Phys. Rev. E 87 053301] is adopted to develop a cavitation bubble collapse model. In the respects of coexistence curves and Laplace law verification, the improved pseudopotential multi-relaxation-time lattice Boltzmann model is investigated. It is found that the thermodynamic consistency and surface tension are independent of kinematic viscosity. By homogeneous and heterogeneous cavitation simulation, the ability of the present model to describe the cavitation bubble development as well as the cavitation inception is verified. The bubble collapse between two parallel walls is simulated. The dynamic process of a collapsing bubble is consistent with the results from experiments and simulations by other numerical methods. It is demonstrated that the present pseudopotential multirelaxation-time lattice Boltzmann model is applicable and efficient, and the lattice Boltzmann method is an alternative tool for collapsing bubble modeling.     

基于WSAN的道路积水监控系统的设计与实现

强降雨及城市排水系统的老化,使得城市道路低洼处积水严重,对市民人身安全、财产、路基、城市交通产生不容忽视的影响。针对该问题,采用无线传感器/执行器网络（WSAN）技术,设计了道路积水监控系统。该系统分为传感/执行层、网络层和应用层三层。传感/执行层的传感器节点使用超声波传感器采集积水信息,执行器节点使用执行器水泵进行排水;网络层网关及汇聚节点使用ZigBee网络和GPRS网络相结合来实现传感/执行层与应用层之间的数据双向传输;应用层服务器储存采集的道路积水信息,调用百度地图API将实时信息显示在web端,并通过网络层发送指令控制积水区域内的执行器水泵动作,实现闭环控制。该系统能够简洁有效地实现道路积水信息的实时共享,可以实现及时排水,具有实际的应用价值。     

仿人耳听觉的助听器双耳声源定位算法

为提高复杂场景下的听障患者的语言理解度,本文提出一种仿人耳听觉的助听器双耳声源定位算法。算法首先借鉴耳蜗分频特性和听觉掩蔽特性,将声音信号进行多通道分解,并提取人耳敏感频带的信号进行双耳时间差(Interaural Time Difference,ITD)估计;然后基于人耳哈斯效应,提取有效的ITD信息;最后采用头相关模型,将ITD转化为声源方向信息。同时,为了改善混响和多干扰声场景下的声源定位能力,本文提出一种多通道的加权联合策略。仿真和场景测试实验表明,算法的抗干扰性强,定位精度高。而且,在7名受试者的理解度测试中,同现有的助听器增强算法相比,结合定位算法的语音增强算法达到3~5dB的性能改善。      

流体-孔隙介质圆柱界面波传播特性

研究流体-孔隙介质圆柱界面波传播特性,分析孔隙介质孔隙率等参数对频散曲线的影响。理论上建立了无限大流体包裹孔隙介质圆柱界面波的模型,利用孔隙介质弹性波动理论,通过数值模拟计算得到流体-孔隙介质圆柱的频散曲线及时域波形,并分析了孔隙介质为开孔和闭孔状态下孔隙介质圆柱半径、孔隙率及渗透率对频散曲线的影响。结果表明,时域上斯通利波可以被明显区分开,孔隙介质圆柱半径的变化改变了圆柱尺度,孔隙率的变化改变了孔隙介质的纵、横波波速,因此对于斯通利波频散曲线的影响较大。而渗透率的变化既不改变圆柱的尺度也不改变孔隙层的纵、横波速度,因此对斯通利波频散曲线影响较小。      

超声方法对于海藻酸钠的降解反应研究

用超声方法对海藻酸钠溶液进行了降解研究,研究了各种因素对降解效果的影响,得出了聚合物溶液特性粘度与降解时间的经验公式。