PWM控制下多电平混合逆变电路的脉宽调制及拓扑分析

PWM和多电平变换是在高压大功率电力电子变换中应用较多的两种技术 ,本文在试验一种新型混合逆变电路的基础上 ,通过分析PWM控制下的多电平混合逆变电路调制方法 ,提出了一种混合单元间电压比取值的方法 ,理论上试图涵盖可能出现的混合逆变电路拓扑     

带能量回馈的电动车交流驱动系统

提出了一种刹车或减速时能量可回馈的电动车交流驱动系统 ,延长了车辆行驶里程 ,提高了能量利用率 ,降低了系统造价。实验结果证明了系统的可行性     

恒压复位双管正激DC-DC变换器

介绍了一种新型的恒压复位双管正激DC-DC变换器。通过外加恒压复位电路，双管正激DC-DC变换器能扩展工作占空比。恒压复位电路由一个开关与二极管并联后与一个复位电容串联组成，并联在直流母线上。在正常工作时，恒压复位电路的开关一直导通， 复位电容直接并联在直流母线上。 当输入掉电时，恒压复位电路的开关关断，复位电容从直流母线断开。这样， 该变换器就有比较恒定的复位电压，可以增大变压器匝数比设计。 与通常的双管正激变换器相比，该变换器的元件应力较低，效率更高。最后，给出了 80V 输入 12V/18A输出的 实验结果。     

FDDI网络适配器ODI驱动程序的原理与实现

本文首先简要介绍了开放数据链路接口ＯＤＩ的结构模型和基本原理，并在此 论述了Ｎｏｖｅｌｌ网中ＦＤＤＩ网络适配器ＯＤＩ驱动程序的实现技术。     

钢管混凝土压弯构件荷载—挠度曲线的全过程分析

本文主要采用筒支梁式加载方案，研究钢管混凝土压弯构件荷载－挠度关系曲线，试验的主要参数是轴压比、剪跨比和含钢率。最后通过理论计算和对试验数据进行回归分析得到极限承载力、极限位移的计算公式和荷载－挠度关系曲线。     

组合励磁永磁同步发电机主发电机的设计方法

提出了组合励磁稀土永磁同步发电机(以下简称HESG)主发电机部分的一种设计方法，该方法可以定量调控发电机外特性的电压变化率，是设计HESG的基础，也能单独设计稀土永磁同步发电机。通过样机的实验验证，说明设计方法是成功有效的。     

Photoreflectance Spectroscopy for Study of Si/SiGe/Si Heterostructure

UHVCVD-grown Si/Si1- xGex/Si heterostructure was investigated by Photoreflectance spectroscopy (PR). The principle of PR used in semiconductor film was thoroughly described. According to the E1 transition energy in the Si1- xGex alloy, the Ge content in SiGe film with constant composition can be accurately characterized. In this study, determine the composition uniformity of larger diameter SiGe epiwafer by PR mapping technique was determined. These results show PR is very promising for Si1- xGex epilayer characterization with constant Ge content and can provide film measurements for production-worthy line monitor.     

Effect of Ion Dose on Growth of Relaxed SiGe Layer on Ion Implantation Si Substrate

Thin strain-relaxed Si0.8Ge0.2 films (57.6 nm) on the 30 keV Ar ion implantation Si substrates for different dose (1 × 1014, 5 × 1014, 3 × 1015 cm-2) were grown by ultra high vacuum chemical vapor deposition (UHVCVD) system.Rutherford backscattering/ion channeling (RBS/C), high resolution X-ray diffraction (HRXRD), Raman spectra as well as atomic force microscopy (AFM) were used to characterize these SiGe films. Investigations by RBS/C as well as HRXRD demonstrate that these thin Sio.8Geo.2 films could indeed epitaxially grow on the Ar ion implantation Si substrates. Under low dose ( 1 × 1014 cm-2) and medium dose (5 × 1014 cm-2) implantation conditions, the relaxation extents of SiGe films are 60.6% and 63.6%, respectively. However, high dose implantation (3 × 1015 cm-2) prompt the strain in epitaxial SiGe film to be close to full relaxation status (relaxation extent of 96.6% ). On the other hand, determinations of RBS/C also indicate the crystalline quality of SiGe film grown on high dose implantation Si substrate is nearly identical to that grown on low dose (1 × 1014 cm-2) implantation Si substrate.     

A fault-tolerant computing method for Xdraw parallel algorithm

The Journal of Supercomputing - Viewshed analysis has widely been used in various spatial analysis applications. But the expense of viewshed computation remains high both in time and space...