首先，论述质量的基本概念、分类和QFD的概念、质量屋、四阶段模式展开。

Firstly, quality concept, quality classification, QFD concept, HOQ and 4 stages model are introduced.

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本文介绍了电能质量的基本概念，阐述了当前电能质量分析仪的国内外研究现状。

The thesis introduces the basic concept of power quality, and expounds the current research situation of analysis instrument for power quality.

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介绍了室内空气质量的基本概念，讨论了影响室内空气质量的因素和室内环境中污染物来源、特点及危害；

This paper introduces the basic concepts of indoor air quality and discusses the factors affecting indoor air quality and the sources, characteristics and harms of indoor air pollutants.

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