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初等几何研究的三策略
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作者 赵龙山 张琪 《九江师专学报》 1992年第6期62-67,共6页
对于初等几何研究,一般人们认为几何的理论已经很完善而没有什么东西可值得研究了。另外也还有很多数学教师想开展一些初等几何研究,可又因没有掌握开展几何研究的方法和策略而效果不佳。鉴于此,本文将通过对具体的几何问题的研究而提... 对于初等几何研究,一般人们认为几何的理论已经很完善而没有什么东西可值得研究了。另外也还有很多数学教师想开展一些初等几何研究,可又因没有掌握开展几何研究的方法和策略而效果不佳。鉴于此,本文将通过对具体的几何问题的研究而提出三个研究策略,供数学教师和数学教育研究工作者参考。 展开更多
关键词 研究策略 条件转换策略 元素运动策略 量级递进策略 几何教学 初等几何研究
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A novel control strategy for load converter of DC isolated distribution system under unbalanced loading conditions 被引量:1
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作者 R.NOROOZIAN M.ABEDI +1 位作者 G.B.GHAREHPETIAN S.H.HOSSEINI 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2009年第6期890-899,共10页
A novel control strategy for the load converter supplying the unbalanced AC load in a DC isolated distribution system is presented. The control algorithm results in balanced and sinusoidal load voltages under unbalanc... A novel control strategy for the load converter supplying the unbalanced AC load in a DC isolated distribution system is presented. The control algorithm results in balanced and sinusoidal load voltages under unbalanced AC loading. The unbalanced load is characterized in the d-q-0 rotating coordinate based on symmetrical sequence components. Also, the mathematical model of the load converter in both a-b-c and d-q-0 coordinates is derived by using the average large signal model. Then, two control strategies for the load converter are presented. The first one uses the conventional d-q-0 controller to ensure the voltage and current regulation. The second one is a newly proposed control strategy based on the decomposition of the voltage and current into in-stantaneous positive, negative, and zero sequences. These three sequences are controlled independently in their own reference frames as DC signals. The performance of the load converter using these two control strategies is compared. Simulation results show the validity and capability of the newly proposed control strategy. 展开更多
关键词 Unbalanced load Power quality Symmetrical components Control strategy
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