模型是一个广义的概念。模型主要有两类。一类是实物模型,它采用缩小和放大几何尺寸的办法,制作出跟原型相似的一种实体模型,如人体模型、心脏模型、飞机模型、桥梁模型、地形沙盘等。它是以研究原形的功能作用、结构特征为目的的一种模型。另一类是理想模型,它是将实物和过程,进行想像和抽象,采用 The model is a broad concept. There are two main types of models. One is the physical model, which adopts a method of reducing and amplifying the geometric dimensions to create a physical model similar to the prototype, such as a human body model, a heart model, an aircraft model, a bridge model, a terrain sand table, and the like. It is a model for the purpose of studying the functional and structural features of the prototype. The other is the ideal model, which is to imagine and abstract physical objects and processes.