电压比例缩放谐波注入永磁同步电机高速驱动方法

为了提高永磁同步电机母线电压利用率,减小电压矢量合成角度偏差,提出了一种基于电压比例缩放谐波注入式脉宽调节方式.谐波注入采用查表式,以减小电流环计算时间,提高电流响应速度.采用电压比例缩放的脉宽调制方式,消除了传统脉宽调制限幅造成的电压矢量计算角度偏差.仿真及实验结果表明,该种脉宽调制方法提高了母线电压利用率,有效抑制了传统脉宽调制方法的电压矢量计算角度偏差,提高电机在高速旋转工况下的电流响应特性.      

波长缩放高频调制全息成象的关系

本文讨论了体积全息系统在α_1≥α_(RC)条件下,具有波长缩放的全息成象关系,运用这些公式对某些例题进行了验算,所获结果与实际基本相符。     

图像几何变换的理论及MATLAB实现

图像几何变换是计算机图像处理领域中的一个重要组成部分,也是值得探讨的一个重要课题。在图像几何变换中主要包括图像的缩放、图像的旋转、图像的移动、图像的剪取、图像的块操作等内容。文章主要探讨了图像的几何变换(主要包括图像的缩放、旋转、剪取等)理论,并在此基础上用M ATLAB实现的过程。     

缩放式喷管燃烧器及其数值模拟

介绍了一种具有自回流能力的缩放式喷管燃烧器的基本结构及工作原理.运用k-ε模型,对喷管燃烧器喉部直径、喉部开孔率及外罩壳长度等结构参数对燃烧器回流特性的影响进行了数值模拟.数值模拟结果表明,当喷管燃烧器入口气流速度在30~55 m/s时,介质回流率近似一常数,喷管喉部开孔率及外罩壳长度存在一个使回流能力达最大的最佳值.     

Nonlinear conductive properties and scaling behavior of conductive particle filled high-density polyethylene composites

The blends prepared by incorporation of carbon black (CB) or graphite powder (GP) into high-density polyethylene (HDPE) matrix have been novel and extensively applied polymeric positive temperature coefficient (PTC) composites. A phenomenological model was proposed on the basis of the GEM equation and the dilution effect of filler volume fraction due to the thermal volume expansion of the polymer matrix. Accordingly, the contribution of the thermal expansion of the matrix to the jump-like PTC transition of the composites was quantitatively estimated and a mechanical explanation was given. It was proved that the contribution of the volume expansion to PTC effect decreased for HDPE/CB composites crosslinked through electron-beam irradiation. Furthermore, the influences of the filler content, temperature and crosslinking on the self-heating behavior as well as the nonlinear conduction characteristics at electrical-thermal equilibrium state were examined. Based on the electric-field and initial resistivity dependence of the self-heating temperature and resistance dependence of the critical field, the mechanisms of the self-heating of the polymeric PTC materials were evaluated. The intrinsic relations between macroscopic electrical properties and microscopic percolation network at electrical-thermal equilibrium state were discussed according to the scaling relationship between the self-heating critical parameter and the conductivity of materials.     

数字图像缩放的原理与硬件实现

在对数字图像的缩放原理进行理论分析的基础上，给出了适合工程应用的简化缩放公式，以数字自动印刷机为例，介绍了用硬件实现数字图像缩放的方法，并对数字图像经过缩放后产生的误差与失真进行了分析。     

缩放微分方程隐式Euler方法的稳定性

给出了非线性缩放时滞微分方程初值问题,ｙ′（ｔ）＝ｆ（ｔ,ｙ（ｔ）,ｙ（ｑｔ）,ｑ∈（０,１）,ｔ≥０,ｙ（０）＝ｙ０。理论解渐近稳定的充分条件及数值方法的渐近稳定性概念,证明了隐式Ｅｕｌｅｒ方法是渐近稳定。     

图片浏览功能的实现

研究利用VC++软件实现病理切片图片浏览功能的技术。提出了一款简洁易用的图片浏览器,它不仅能够产生类似常用看图软件ACDSee32中拖动图像的浏览效果,而且能够在浏览缩图后不用切换即可浏览大图。     

Fast image retargeting based on strip dividing and resizing

Based on image strip dividing, an effective and fast image retargeting algorithm is proposed for resizing images. First,we construct the image energy map using gradient magnitude of the pixels and calculate the accumulated energy of each column,dividing the image into several strips by integrating similar energy columns. The reduced amount of dimension is decided in inverse proportion to the average energy for each strip. Then we retarget the image combining scaling with cropping in terms of each strip＇s reduced ratio. Experiment results show that the proposed algorithm is capable of implementing fast image retargeting and preserving both the local structures and the global visual effect of the image.     

探讨利用SwingJava2D实现矢量图效果

本文阐述了如何利用Swing/Java2D绘制图形,并着重论述了如何实现矢量图的缩放、拖拽等基本操作。