A pyramid provides a useful conceptual model for organizing scientific knowledge. 金字塔给科学知识的组织提供了一个有用的概念性模型。
The model researchers have paid more attention to the additive effect models, and run some experiments to test the additivity principle. 加性模型受到研究人员的重视，并对加性原理进行了实际检验。
Firstly, an average performance index containing tracking error and control energy over a class of additive model errors is defined. 首先针对一类相加模型误差的描述，定义了一个平均意义上的包含跟踪误差和控制能量的性能指标。
