永磁同步伺服电动机的动态参数

动态参数是影响伺服电动机动态性能最主要的因素之一.动态参数的高低直接决定伺服电动机动态及稳态性能的好坏.对传统的伺服电动机而言,几个主要的动态参数都有较清晰的定义和概念,长期以来在工程实践中广泛使用.但对正弦波驱动的永磁伺服电动机来说,电机的力矩常数Kt、反电势常数Ke、电气时间常数τe、机械时间常数τm和阻尼因数D等都有了新的变化,实践中常引起误解和混淆.文中主要分析永磁同步伺服电动机几个动态参数的含义以及和传统参数之间的差异,并从控制系统的要求出发,对几个最基本的动态参数和参数之间的相互关系进行分析,得出了一些实用的结论.     

金隆闪速炉精矿喷嘴的优化

介绍金隆公司闪速炉精矿喷嘴的结构特点和运行情况,针对运行中存在的问题,通过优化操作参数、改进结构,喷嘴的性能得到了很大改善。     

LaNi4.25Al0.75合金的吸放氚性能研究

在真空系统中,对LaNi4.25Al0.75合金的氘活化特性进行测试.测定了该合金在不同温度下的吸放氚速率曲线和P-C-T曲线,获得了LaNi4.25Al0.75T x吸、放氚的标准焓值和标准熵值.LaNi4.25Al0.75T2.5合金的生成标准焓值和标准熵值分别为(-31.8±0.8) kJ·mol-1和(-76.5±2.4) J·mol-1·K-1,其解析值分别为(-36.5±0.5) kJ·mol-1和(-84.2±1.5) J·mol-1·K-1.用四极质谱计测定了材料吸附氚气和贮存7 d时释放氚的纯度,并进行了比较.     

激光强化处理参数对轧辊表面性能的影响

通过试验，研究了激光功率、光斑直径、扫描速度、搭接量和合金粉含量等激光处理工艺参数对轧辊表面性能的影响，结果表明，轧辊表面经激光淬火处理后。性能稳定，耐磨性和抗疲劳性均有所提高，达到了生产要求．     

基于屏栅电离室的双参数谱仪研制及其应用

以屏栅电离室为基础，同时引出其阳级和阴极信号，研制了1台能够同时记录两路信号的双参数谱仪，在DEC－3000工作站上编制程序，实现了双维谱数据的获取、显示和存储。利用所建立的谱仪，测量了α放射源的双维谱，计算了α粒子的角分布，并讨论了如何利用角分布来校正活度测量中自吸收和反散射的影响以及改善电离室阳极能谱的能量分辨率。     

Mapping of Sahelian vegetation parameters from ERS scatterometer data with an evolution strategies algorithm

The West African Sahel rainfall regime is known for its spatio-temporal variability at different scales which has a strong impact on vegetation development. This study presents results of the combined use of a simple water balance model, a radiative transfer model and ERS scatterometer data to produce map of vegetation biomass and thus vegetation cover at a spatial resolution of 25 km. The backscattering coefficient measured by spaceborne wind scatterometers over Sahel shows a marked seasonality linked to the drastic changes of both soil and vegetation dielectric properties associated to the alternating dry and wet seasons. For lack of a direct observation, METEOSAT rainfall estimates are used to calculate temporal series of soil moisture with the help of a water balance model. This a priori information is used as input of the radiative transfer model that simulates the interaction between the radar wave and the surface components (soil and vegetation). Then, an inversion algorithm is applied to retrieve vegetation aerial mass from the ERS scatterometer data. Because of the nonlinear feature of the inverse problem to be solved, the inversion is performed using a global stochastic nonlinear inversion method. A good agreement is obtained between the inverse solutions and independent field measurements with mean and standard deviation of −54 and 130 kg of dry matter by hectare (kg DM/ha), respectively. The algorithm is then applied to a 350,000 km² area including the Malian Gourma and Seno region and a Sahelian part of Burkina Faso during two contrasted seasons (1999 and 2000). At the considered resolution, the obtained herbaceous mass maps show a global qualitative consistency (r²=0.71) with NDVI images acquired by the VEGETATION instrument.     

Improved estimation of defocus blur and spatial shifts in spatial domain: a homotopy-based approach

This paper presents a homotopy-based algorithm for the recovery of depth cues in the spatial domain. The algorithm specifically deals with defocus blur and spatial shifts, that is 2D motion, stereo disparities and/or zooming disparities. These cues are estimated from two images of the same scene acquired by a camera evolving in time and/or space. We show that they can be simultaneously computed by resolving a system of equations using a homotopy method. The proposed algorithm is tested using synthetic and real images. The results confirm that the use of a homotopy method leads to a dense and accurate estimation of depth cues. This approach has been integrated into an application for relief estimation from remotely sensed images.     

狄利克雷积分的几种计算方法

利用含参量非正常积分的一些性质,给出了狄利克雷积分integral from n=0 to +∞(sinx)的几种计算方法。     

一种矢量控制型变频器的设计方案介绍

对美国A B公司生产的 1336IMPACT变频器进行了深入研究 ,剖析了该型号变频器的矢量控制算法、参数自整定方法和无速度传感器运行方式下的参数辨识方法等细节问题 ,并在此基础上总结出了系统的控制方案和设计思想 ,得到了详细的控制系统结构     

基于EDA9011的工频交流电参数测量仪

采用EDA90 11单相电参数数据采集模块 ,以单片机为核心设计一种参数智能测试仪 ,该测试仪可实现对工频交流电路的电流、电压的真有效值及有功功率、无功功率、功率因数及累计电量等电参数的数据采集