CET4--1

Throughout this long, tense election, everyone has focused on the presidential candidates and how they'll changed America. Rightly so. But selfishly. I'm more fascinated(着迷) by Michelle Obama and what she might be able to do, not just for this country, but for me as an African-American woman. As the potential(潜在的) First Lady, she would have the world'd attention. And that means that for the first time people will have a chance to get up close and personal with the type of African-American woman they so rarely see.


Usually, the live of black women go largely unexamined. The prevailing(流行的) theory seems to be that we're all hot-tempered(急脾气的) single mothers who can't keep a man. Even in the world of make-believe, black women still can't excape the stereotype of being eye-rolling(眼睛轧 ), oversexed females raised by our never-married, alcoholic(酗酒的) mothers.


These images have helped define the way all black women are viewed, including Michelle Obama. Before she ever gets the chance to commit to a cause(从事事业), charity(慈善) or foundation as First Lady, her most urgent(急迫的) and perhaps most complicated(复杂的) duty may be simply to be herself.


It won't be easy. Because few mainstream publications have done in-depth features on regular(经常) African-American women, little is known about who we are, what we think and what we face on a regular basis (经常). For better or worse, Michelle will represent us all.


Just as she will have her critics(批评者), she will also have millons of fans who usually have little interest in the First Lady. Many African-American blogs have written about what they'd like to see Michelle bring to the White House--mainly showing the world that a black woman can support her man and raise a strong black family. Michelle will have to work to please everyone--an impossible task. But for many African-American women like me, just a little of her poise(沉着), confidence(自信) and intelligence(智慧) will go a long way in changing an image that's been around for far too long.

带开环升压转换器和逆变器的太阳能光伏系统 太阳能光伏系统驱动开环升压转换器和SPWM逆变器提供波形稳定、设计简单的交流电的模型 Simulink模型展示了一个完整的基于太阳能光伏的直流到交流电力转换系统,该系统由简单、透明、易于理解的模块构建而成。该系统从配置为提供真实直流输出电压的光伏阵列开始,然后由开环DC-DC升压转换器进行处理。升压转换器将光伏电压提高到适合为单相全桥逆变器供电的稳定直流链路电平。 逆变器使用正弦PWM(SPWM)开关来产生干净的交流输出波形,使该模型成为研究直流-交流转换基本操作的理想选择。该设计避免了闭环和MPPT的复杂性,使用户能够专注于光伏接口、升压转换和逆变器开关的核心概念。 此模型包含的主要功能: •太阳能光伏阵列在标准条件下产生~200V电压 •具有固定占空比操作的开环升压转换器 •直流链路电容器,用于平滑和稳定转换器输出 •单相全桥SPWM逆变器 •交流负载,用于观察实际输出行为 •显示光伏电压、升压输出、直流链路电压、逆变器交流波形和负载电流的组织良好的范围 •完全可编辑的结构,适合分析、实验和扩展 该模型旨在为太阳能直流-交流转换提供一个干净高效的仿真框架。布局简单明了,允许用户快速了解信号流,检查各个阶段,并根据需要修改参数。 系统架构有意保持模块化,因此可以轻松扩展,例如通过添加MPPT、动态负载行为、闭环升压控制或并网逆变器概念。该模型为进一步开发或整合到更大的可再生能源模拟中奠定了坚实的基础。
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