非平稳信号的快速傅里叶变换与小波分析的比较

在对通信系统信号进行分析时,非平稳信号是经常遇到的。采用快速傅里叶变换和小波变换对通信系统信号进行分析,比较了分析结果,证明小波分析更适合于突发信号的分析。最后给出了Matlab实验结果。     

9200kW同步电动机全压异步启动及其励磁装置

从结构性能、直接启动、励磁装置等方面全面介绍了大型同步电动机全压异步启动的方法。     

电熔氧化镁炉弧压系数与弧流系数的测定

在实际测试的基础上，给出了电熔镁炉的弧压系数和弧流系数，为进一步研究电熔镁炉提供依据。     

关于缩短大电流开关二极管反向恢复时间的研究

通过长期的工作实践，阐述了适当条件下的金扩散对缩短反向恢复时间，提高二极管2CK28开关速度，满足了反向恢复时间，改善了二极管的反向特性。     

利用电阻场板提高SOI-LIGBT的性能

通过在SOI-LIGBT中引入电阻场板和一个p-MOSFET结构,IGBT的性能得以大幅提高.p-MOSFET的栅信号由电阻场板分压得到.在IGBT关断过程中,p-MOSFET将被开启,作为阳极短路结构起作用,从而使漂移区的过剩载流子迅速消失,IGBT快速关断.而且由于电场受到电阻场板的影响,使得过剩载流子能沿着一个更宽的通道流过漂移区,几乎消去了普通SOI-LIGBT由于衬偏造成的关断的第二阶段.这两个因素使得新结构的关断时间大大减少.在IGBT的开启状态,由于p-MOSFET不导通,因此器件的开启特性几乎与普通器件一致.模拟结果表明,新结构至少能增加25%的耐压,减少65%的关断时间.     

一种升压式PFM DC-DC转换器的设计

讨论了一种PFM升压式DC－DC电压转称器的设计，重点对其关键的基准电压产生，振荡控制信号产生及比较器设计进行了分析，并采用3μmCOMOS工艺完成芯片的设计。     

A novel method of suppressing the inrush current of transformers by using a series‐connected voltage‐source PWM converter

This paper proposes a novel method of suppressing the inrush current of transformers. A small‐rated voltage‐source PWM converter is connected in series to the transformers through a matching transformer. As the connected PWM converter serves as a resistor for the source current, no inrush phenomena occurs. The required rating of the PWM converter, which serves as the damping resistor for the inrush phenomena, is 1/400 that of the main transformers in single‐phase circuits. In three‐phase circuits, it is 1/900. The basic principle of the proposed method is discussed. Digital computer simulation is implemented to confirm the validity and excellent practicability of the proposed method using the PSCAD/EMTDC. A prototype experimental model is constructed and tested. The experimental results demonstrate that the proposed method can perfectly suppress the inrush phenomena. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(4): 56–65, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20174     

Thermodynamic analysis of solar photovoltaic cell systems

The thermodynamic characteristics of solar photovoltaic (PV) cells are investigated from a perspective based on exergy. A new efficiency is developed that is useful in studying PV performance and possible improvements. Exergy analysis is applied to a PV system and its components, and exergy flows, losses and efficiencies are evaluated. Energy efficiency is seen to vary between 7% and 12% during the day. In contrast, exergy efficiencies, which incorporate the second law of thermodynamics and account for solar irradiation exergy values, are lower for electricity generation using the considered PV system, ranging from 2% to 8%. Values of “fill factors” are determined for the system and observed to be similar to values of exergy efficiency.     

文昌A凹陷油气成藏特征与分布规律探讨

文昌A凹陷位于珠江口盆地西部,是一个发育文昌组和恩平组两套湖相烃源岩复合成藏的油气区。根据特征生物标志化合物与碳同位素组成的油岩对比结果,可将文昌A凹陷发现的原油划分为两类,即文昌Ⅱ型和恩平型,前者来自文昌组浅湖相烃源岩,后者源于恩平组湖相烃源岩;天然气主要源于恩平组烃源岩,也可能有文昌组烃源岩凝析气或裂解气的贡献。文昌A凹陷油气两期成藏,早期成油,晚期聚气及轻质油,其油气分布主要受烃源岩有机相、热演化程度和运移分馏作用等因素的控制,凹陷中部以气为主,凹陷边缘气油共存,而凸起上以油为主。     

船艇电站仿真与综合管理系统

论文介绍了船艇电站模拟器的组成和实时仿真功能,着重描述了多层次的图形管理系统及其仿真界面。课题将多媒体课件制作与模拟器有机地结合,涵盖了船舶主要电气设备的控制电路,既利于实践训练又便于原理的讲解,并在实践中取得了良好的效果。