单片机控制的PWM调速装置的研究

与交流电动机相比,直流电动机结构复杂,成本高,运行维护困难。但是直流电动机具有良好的调速性能、较大的起动转矩和过载能力强等许多优点,因此在许多行业中仍得到了广泛的应用。文章介绍了一种利用单片机控制的PWM调速装置实现小功率直流电动机调速的方法,具体详述了电路的设计思想、电路的组成以及工作原理。     

Electrostatic actuation of three-dimensional MEMS mirrors using sidewall electrodes

We propose and demonstrate electrostatic sidewall-electrodes actuation of three-dimensional (3-D) microelectromechanical systems (MEMS) gimbal mirrors. The linearity of the mirror angle dependence on actuation voltage is improved with the sidewall-electrodes actuation. In addition, the undesired spring-softening effect commonly found in electrostatic actuation, where the mirror resonance frequency decreases with increased tilt angle, is significantly reduced. Sidewall actuation enables superior performance of 3-D MEMS mirrors including large pull-in angles, reduced actuation voltages, improved device reliability, and fast switching times.     

Structure, Phonon Vibration, and Spin Correlation of LaBa2Cu3−x Co x O y

Polycrystalline samples LaBa₂Cu_3?xCo _x O _y (0 ≤ x ≤ 1.0) were synthesized by solid state reaction method. The structure, phonon vibration, conduction, and spin correlation were investigated by means of X-ray diffraction, infrared spectra, resistivity, and electron spin resonance. It is found that there are orthorhombic–tetragonal and tetragonal–orthorhombic structural transitions with Co doping, and the conduction behavior changes from metallic to semiconducting. With the increase of Co content, the Cu(1)—O(1) phonon mode around 531 cm^?1 softens, the Cu(2)—O(2) phonon mode around 657 cm^?1 hardens, and the Cu(1)—O(4) mode around 583 cm^?1 is nearly unchanged. The Cu²⁺ spins tend to localize with Co doping. The changes in structure, phonon vibration, and spin correlation with Co doping are analyzed and discussed.     

基于计算机视觉的电厂车辆智能监测系统设计与实现

针对电厂运煤车辆的管理,设计并实现了一个基于计算机视觉的电厂运煤车辆智能监测系统.提出了一种基于颜色分割和数字形态学处理相结合的车牌定位算法和一种基于Sobel灰度边缘算子的车牌倾斜校正算法.实际应用表明,该系统有很强的鲁棒性,可以处理污损、变形、各种光照条件下的车牌,并且速度快、准确率高     

基于风险管控的历史遗留硫磺冶炼废渣综合治理效果

为解决赤水河源头流域(云南段)历史遗留硫磺冶炼废渣40多年无序堆积导致流域水体持续酸化的污染问题,通过对“自然衰减”“异位修复”“风险管控”等治理途径分析,提出“风险管控+生态修复”模式开展了该区域内酸性废渣和废水的示范工程治理。在查明治理区域污染因子的基础上,采取“废渣防流失、复合阻隔控制、适生植物配比、污水收集处理和运行监测管理”的集成风险管控技术,分析工程实施前、实施中和实施后的固废属性,以及地表水、地下水和废渣渗滤液中污染因子的变化。结果表明：在投加0.35%～0.65%比例生石灰条件下,固废属性从第Ⅱ类一般工业固废改性为第Ⅰ类一般工业固废;工程完工时,地下水pH即可达标,硫酸盐超标倍数从最大5.3倍削减至1.2倍;工程实施3个月后,渗滤液pH稳定达标,硫酸盐超标倍数从最大3.2倍削减至1.7倍;工程实施7个月后地表水pH达标。基于风险管控的历史遗留硫磺冶炼废渣综合治理,能够满足管控目标,并初步完成了技术推广和应用。     

ADS熔盐散裂靶中子学性能研究

与传统加速器驱动次临界系统（ADS）采用金属靶作为散裂中子靶的设计不同,加速器驱动次临界熔盐堆（AD-MSRs）采用靶堆一体的设计,直接使用燃料熔盐作为散裂中子靶。由于熔盐靶的中子学性能直接影响AD MSRs的能量放大系数、核废物的嬗变和核燃料增殖的效率,所以本研究基于MCNPX程序,详细计算了高能质子轰击氟盐和氯盐两种熔盐靶产生的散裂中子产额、散裂中子能谱、能量沉积分布以及散裂产物等中子学性能,并与液态Pb和铅铋共熔体（LBE）两种液态金属靶进行了对比。计算结果表明,熔盐靶在散裂中子产额上与液态金属靶有一定的差距,但熔盐靶内能量沉积分布的梯度较小,更有利于靶区的热量导出。与液态Pb和LBE靶相比,熔盐靶的散裂产物中包含更多的气体以及高质量数的α发射体核素。     

基于PS021的无线应变测量系统研究

基于应变的测量需求越来越多,本文针对传统的应变测量系统的各种弊端,设计了基于TDC的应变测量系统。本文利用基于TDC技术(时间数字转换器)的PS021芯片来设计应变测量系统。在数据传输方面,对比了常用的数据传输技术,最终采用基于微功射频技术的NanoPAN5375来搭建无线数据传输系统。     

Topset-to-forest rollover trajectories as reliable predictors of sediment-volume partitioning into deep-lake areas

Topset-to-forest rollover trajectories and their relation to sediment-and sand-budget partitioning into deep-lake areas are far from being well understood,as co...     

Current State and Prospect of China’s Oil and Gas Pipeline Development

By the end of 2010, China has completed 85,000 kilometers of oil and gas pipelines in length, of which natural gas pipelines were 45,000 kilometers, crude oil pipelines were 22,000 kilometers, and products pipelines were 18,000 kilometers. An oil and gas network that covers China     

基于关联矩阵的输电线路广域后备保护研究

介绍了广域保护的背景和现实意义,通过获取电力系统中的多点信息来实现新的保护和控制算法.在此基础上借助广域保护的分布式系统结构,采用基于变电站智能电子设备(IED)保护动作系数和关联系数矩阵的输电线路广域后备保护算法,实现新的电网故障判别机制,并结合具体的电网验证了算法的合理性和有效性.