基于Zigbee的无线粮情监控网络中测量节点的设计

针对传统有线粮情监控系统存在的缺陷,提出"平面分离、上下贯通"的无线粮情监控网络的设计思路,实现了设计目标的基本单元测量杆的功能结构,规划了基于Zigbee的无线粮仓温湿度监控网络.根据节能需求将无线监控网络中的节点分为测量节点和路由节点,完成了测量节点的接口电路和主程序设计,并对测量节点中的关键技术进行了阐述.     

Fast k-nearest neighbor search algorithm based on pyramid structure of wavelet transform and its application to texture classification

Traditional fast k-nearest neighbor search algorithms based on pyramid structures need either many extra memories or long search time. This paper proposes a fast k-nearest neighbor search algorithm based on the wavelet transform, which exploits the important information hiding in the transform coefficients to reduce the computational complexity. The study indicates that the Haar wavelet transform brings two kinds of important pyramids. Two elimination criteria derived from the transform coefficients are used to reject those impossible candidates. Experimental results on texture classification verify the effectiveness of the proposed algorithm.     

Comparison of two novel MRAS based strategies for identifying parameters in permanent magnet synchronous motors

Two model reference adaptive system (MRAS) estimators are developed for identifying the parameters of permanent magnet synchronous motors (PMSM) based on the Lyapunov stability theorem and the Popov stability criterion, respectively. The proposed estimators only need online measurement of currents, voltages, and rotor speed to effectively estimate stator resistance, inductance, and rotor flux-linkage simultaneously. The performance of the estimators is compared and verified through simulations and experiments, which show that the two estimators are simple, have good robustness against parameter variation, and are accurate in parameter tracking. However, the estimator based on the Popov stability criterion, which can overcome parameter variation in a practical system, is superior in terms of response speed and convergence speed since there are both proportional and integral units in the estimator, in contrast to only one integral unit in the estimator based on the Lyapunov stability theorem. In addition, the estimator based on the Popov stability criterion does not need the expertise that is required in designing a Lyapunov function.     

基于ARM9的航空相机测控系统设计与实现

性能测试是航空数码相机生产和装备过程中非常重要的一个环节,对其的使用评估有着不可替代的作用;以三星的ARM9处理器S3C2440A和Windows CE操作系统为核心,结合现代接口技术,介绍了某型航空数码相机地面检测系统总体设计思路和系统构成,重点分析了主体电路的硬件设计和Windows CE系统下相关软件的编写;通过BCD拨码器,串口电路,处理器和LED数码管组成模块模拟飞行状态输入和显示,编写相关软件完成了图像数据的格式转变和实时显示;实际使用结果显示,该检测系统运行稳定可靠,具有一定的实用性和参考价值。     

智能引爆机器人的研究与制作

为了代替人类完成危险情况下的工作任务,例如,进行危桥、危楼的爆破,危险环境下重要物品的拾取等;研究与制作了基于单片机技术和RS232串口通信技术的远程遥控引爆机器人;重点解决智能引爆机器人上位机控制软件的开发、RS232串口通信技术、单片机及传感器电路设计、无线摄像头的数据采集、多自由度机械手的设计等技术模块,利用Pro/E对机械结构仿真设计及Protel99se进行硬件电路仿真设计;通过机械结构和电子电路仿真,设计并制作了机器人实体结构和控制系统硬件电路,经过多次实物实验,设计制作的机器人能圆满地实现预期功能,控制系统运行状态良好.     

微电子器件温度分布测试技术研究

为改善微电子器件性能,提高可靠性,确定筛选、考核条件等都必须对器件的结温、表面温度分布以及热斑等热特性进行精确测量,红外热像法是当前测量微电子器件热特性最有效的方法之一。文章针对InfrascopeⅡ型显微红外热像仪在实际应用中如何提高其测温准确度和一致性等问题进行了研究,重点分析了样品发射率、背景环境和大气衰减等因素的影响,并给出验证解决方案,取得了满意的结果。     

固有频率和阻尼度的测试方法研究

文章介绍了阶跃激励法、正弦激励法、脉冲激励法三种动态扭矩计量测试方法,并对不同时间做的两次试验进行了对比,得出的数据相差在3%以内,证明了上述动态特性的测试方法具有重复性和追溯性,可用作扭矩传感器动态特性的测试。     

Adaptive neural dynamic surface control for servo systems with unknown dead-zone

An adaptive neural controller is proposed for nonlinear systems with a nonlinear dead-zone and multiple time-delays. The often used inverse model compensation approach is avoided by representing the dead-zone as a time-varying system. The “explosion of complexity” in the backstepping synthesis is eliminated in terms of the dynamic surface control (DSC) technique. A novel high-order neural network (HONN) with only a scalar weight parameter is developed to account for unknown nonlinearities. The control singularity and some restrictive requirements on the system are circumvented. Simulations and experiments for a turntable servo system with permanent-magnet synchronous motor (PMSM) are provided to verify the reliability and effectiveness.     

HCAA:一种哈希冲突过度的动态解决算法

HASH表作为一种快速查询的数据结构,在防火墙等网络安全应用中得到了广泛的应用。然而,攻击者可能通过一些手段对这些应用发动HASH攻击使其失去响应,从而使某些恶意的数据流能够逃脱网络安全应用的管理和控制。提出一种动态的哈希冲突过度的解决算法—HCAA(Hash Collision-Acceptable Algorithm)算法,该算法在哈希冲突过于集中时通过动态申请HASH表并使用不同哈希函数来对冲突数据流进行处理,使冲突在可接受的范围内。实验结果表明,与已有方法相比,HCAA算法能在使用更少HASH表项的情况下获得更均衡的HASH效果,从而能对数据流进行更快的HASH操作。     

Superconvergence and Extrapolation Analysis of a Nonconforming Mixed Finite Element Approximation for Time-Harmonic Maxwell’s Equations

In this paper, a nonconforming mixed finite element approximating to the three-dimensional time-harmonic Maxwell’s equations is presented. On a uniform rectangular prism mesh, superclose property is achieved for electric field E and magnetic filed H with the boundary condition E×n=0 by means of the asymptotic expansion. Applying postprocessing operators, a superconvergence result is stated for the discretization error of the postprocessed discrete solution to the solution itself. To our best knowledge, this is the first global superconvergence analysis of nonconforming mixed finite elements for the Maxwell’s equations. Furthermore, the approximation accuracy will be improved by extrapolation method.