基于MSP430单片机的电磁流量计设计

提出了采用三值梯形波励磁方式的电磁流量计设计。构建了采用MSP430F149单片机的电磁流量计样机。试验表明，三值梯形波励磁方式在小流速阶段，相对误差在-6.26％以内，小于矩形波励磁方式的-7．06％，可以减弱微分干扰，提高测量准确度。中对系统的软硬件设计作了详细的介绍。     

MSP430F449在新型流量计中的应用

提出了采用三值梯形波励磁方式的电磁流量计设计。构建了采用MSP430F449单片机的电磁流量计样机。试验表明，三值梯形波励磁方式在小流速阶段，相对误差在-4．8％以内，小于矩形波励磁方式的-6．9％，可以减弱微分干扰，提高测量准确度。文中对系统的软硬件设计作了详细的介绍。     

电容式电磁流量计信号处理新方法研究

电容式电磁流量计采用电容耦合的方式检测流量信号,其信号微弱、易受干扰、信噪比低,使得流量信号检出难度较大。对此,本文在信号处理中引入了互相关检测技术,设计了一种适合矩形波励磁下的电磁流量计信号特点的旋转电容滤波方式,采用的滤波器具有很高的信噪比,并且实现简单。在此基础上研制了一套原理样机,实验结果表明,该方法是有效的。     

基于Walsh变换的谐波分析浆液型电磁流量计信号处理方法

针对浆液型电磁流量计的矩形波励磁技术,提出一种更加符合矩形波特点的Walsh变换法。对基于Walsh变换的谐波分析方法进行实验验证其可行性和实际效果。实验表明在不提升励磁频率的前提下,该谐波分析方法可以一定程度克服浆液噪声引起的流量信号波动。从而为浆液型电磁流量计的谐波分析方法提供了一种新的思路和理论依据。     

基于低频正弦波励磁方式的电磁流量计设计

提出了一种采用低频正弦波励磁方式的电磁流量计的设计方法,并采用新型的信号处理方法使其比传统的信号处理方法更加简便可靠.实验表明:低频正弦波励磁方式在小流速阶段,可以减弱微分干扰的影响,提高流量计零点稳定性和测世准确度.     

电厂发电机励磁系统的控制方法研究北大核心CSCD

为了更好地运用励磁系统对电力系统进行控制,将线性最优励磁控制应用到励磁系统。首先,采用古典控制方式,由PID+PSS控制的励磁系统对发电系统进行控制,由发电机的运转情况来观察古典励磁控制方式的控制效果;然后,采用线性最优励磁控制对发电系统进行控制,除了改变励磁控制器以外,其他都与原系统设置相同。并且,在系统稳定后加入短路干扰及突加负载的干扰,通过观察系统对干扰的反应来对比分析古典励磁控制和线性最优励磁控制的效果。实验结果表明,相对于古典控制方式,线性最优励磁控制可使振荡幅值更小,振荡时间更短,曲线更加平滑。     

励磁系统的优化

通过对发电机励磁方式的应用比较,从发电机励磁系统对电力系统稳定性、继电保护等的影响以及经济性等方面进行论述,提出辽河油田电力集团发电机宜采用单管IGBT斩波式励磁调节器.     

基于GMR磁传感器的钢丝绳励磁结构设计

为实现钢丝绳无损检测设备对钢丝绳局部缺陷（LF）和截面损失（LMA）的检测,在基于GMR传感器的基础上设计钢丝绳励磁装置。通过高灵敏度GMR传感器的多层排布方式来减小漏磁信号中的干扰。对励磁方式提出永磁励磁法与直流励磁法相结合的复合励磁法,可很好地调整励磁强度,同时分析了励磁装置中各参数对励磁性能的影响,给出信号检测电路,总体设计可满足钢丝绳无损检测设备对LF和LMA的检测要求。     

基于剩磁原理的微功耗脉冲励磁方法研究

针对目前因恒流源励磁方法功耗过大而无法满足电磁水表微功耗要求的问题,提出了基于剩磁原理的微功耗脉冲励磁方法。通过对电磁流量传感器磁场的工作方式进行分析,选择具有高剩磁、低矫顽力的矩形磁滞材料制作磁路,采用双向窄脉冲电压为励磁线圈供电,使磁场稳定反转。根据这一原理,设计了脉冲励磁磁路和双向脉冲发生电路,并进行试验测试。测试结果表明,相对于恒流励磁方法,基于剩磁原理的脉冲励磁方法可以大幅度降低励磁功耗,并且得到稳定的工作磁场,有利于提高电磁水表的使用寿命和流量信号的稳定性。     

新型混合励磁导向系统的状态反馈控制

提出一种新型混合励磁导向系统,阐述其结构特点与工作机理,利用等效磁路法得出磁力解析表达式,结合牛顿第二定律和绕组电路方程,推导出混合励磁导向系统的运动方程.建立以气隙、速度、电流为状态变量的线性化电压控制模型,设计出状态反馈控制器并进行仿真.仿真结果表明:新型混合励磁系统的结构是合理的,理论分析和建模方法是切实可行的.设计的反馈控制器在无干扰情况下,控制电流保持为零,在干扰条件下通过调整控制电流能够实现导向系统的稳定导向,研究成果为此类混合励磁导向系统的工业应用提供理论价值和设计参考.     

Investigation on a new compact wideband rhombic dielectric resonator antenna

In this article, a new rhombic dielectric resonator antenna (DRA) is proposed. Dominant mode and a few of the higher order modes that are excited in this DRA are identified through eigen mode analysis performed through computer simulation technology (CST) simulation. Empirical formulae for calculating the resonant frequency of these identified modes are developed through curve‐fitting approximation. Feeding techniques and possible ways of exciting some of these modes generated in such DRA are also detailed. Investigations are further carried out to identify appropriate feed positions to achieve broadband operation of such DRA geometry. The radiation patterns at different frequencies and variation of gain within the antenna bandwidth are measured for a fabricated prototype and compared with the simulation results.     

A polarization‐reconfigurable array design based on mode combination technique

This article reports a novel polarization‐reconfigurable antenna array using the technique of mode combination (MC). It can electronically alter its polarization states between left‐hand circular polarization mode, right‐hand circular polarization mode, and linear polarization (LP) mode. The antenna array consists of 2 × 2 microstrip antenna elements with one L‐slot on each square patch and two PIN diodes located in the slot region. Instead of degenerating circular polarization (CP) and LP modes by exciting different radiation parts of the antenna element, the LP one is combined by orthogonal CP modes generated by adjacent elements of the proposed antenna array. To verify the concept, a prototype is manufactured and tested. Experimental results show that the proposed antenna has an overlapped ?10 dB impedance bandwidth of around 11.2% for both CP modes and the LP one. The realized maximum gains are around 7.5 dB for the CP modes and 5.6 dB for the LP mode, which are satisfactory for wireless local area network in wireless communication systems.     

Dielectric resonator based two‐port dual band antenna for MIMO applications

This article investigates a dual band multiple input multiple output (MIMO) cylindrical dielectric resonator antenna (cDRA) for WLAN and WiMAX applications. It consists of two symmetrical orthogonally placed radiators. Each radiator is excited through a narrow rectangular aperture with the help of a microstrip line. For higher mode excitation, the proposed structure uses dual segment DRA which apparently looks like stacked geometry. The aperture fed dielectric resonator works as a feed for upper cDRA to generate higher order mode. The presented radiator covers the band between 3.3‐3.8 GHz and 5‐5.7 GHz. The measured isolation is better than 20 dB in the desired band. The average gain and radiation efficiency achieved for the proposed antenna is 6.0 dBi and 85%, respectively at the operating frequency band. In the proposed geometry, broadside radiation patterns are achieved by exciting HEM_11δ and HEM_12δ modes in a stacked geometry. Different MIMO performance parameters (ECC, DG, MEG, and CCL) are also estimated and analyzed. The prototype of proposed antenna is fabricated and tested. The measured outcomes are in good accord with the simulated one.     

基于J2ME的地理信息数据采集的系统分析与实现

Java开发平台的微型版J2ME和蓝牙技术给无线通讯提出了新的解决方案,在支持J2ME技术的Java手机上,结合JSR-82技术规范,建立了适合移动用户使用的地理信息数据采集系统,从而增强了智能手机的功能。本文以Java手机与蓝牙GPS传输数据为主要内容,设计和实现了一个原型系统并进行了实验。     

Robotic manipulation using an open-architecture industrial arm: a pedagogical overview [Education]

Robotics education at the undergraduate level is most effective as a coupling between theoretical concepts and tangible experiments. Making this connection effective requires a pragmatic way of applying the traditional robotic material to exciting laboratory exercises. A course recently offered in Harvard's School of Engineering and Applied Sciences, simply titled "Introduction to Robotics," utilizes an open-architecture robotic arm to give students handson experience with topics that they encounter in lecture. None of the experiments conducted in this course are wholly novel; however, the use of an open-architecture hardware or software system enables the instructor to rapidly prototype lab exercises with minimal effort. This column will give an overview of the apparatus and experiments used for this course.     

Design approach for dual element hybrid MIMO antenna arrangement for wideband applications

This communication explains the designing of two‐port based hybrid radiator for multiple‐input‐multiple‐output (MIMO) applications. Hybrid radiator includes U‐shaped printed line and ring dielectric resonator antenna (ri‐DRA). Wideband characteristics have been achieved by exciting both the U‐shaped printed line along with ri‐DRA. The U‐shaped metallic line acts as a magnetic dipole and helps to excite fundamental hybrid mode (HE_11δ) in the ri‐DRA. Dual L‐shaped and a rectangular defect have been created in ground plane for achieving wideband isolation over the working frequency band. Optimized Scattering parameters and far‐field results are verified by fabricating and testing of antenna prototype. Experimental outcomes confirm that the proposed MIMO antenna gives wider impedance bandwidth (80%), improved port isolation (better than 18 dB), stable gain (~ 4 dB), and radiation pattern. Various MIMO performance factors are analyzed and instituted in the tolerable boundaries.     

AudiMeters：高维连续数据可听化研究

高维连续数据的数据-声音映射是可听化应用设计研究的重点和难点.提出了多通道-多维度数据-声音映射模型,支持多通道映射、多维度映射和混合映射,可以充分利用各种声音参数.实现了可听化汽车仪表原型系统Au-diMeters,采用混合映射对转速、时速、水温和油量等数据进行可听化显示,验证了多通道-多维度数据-声音映射模型的可行性.