The activities involved in the design process can be classified largely as two types：synthesis and analysis．As illustrated in Fig. 10-1，the initial design activities（such as identification of the design need，formulation of design specifications，feasibility study with collecting relevant design information，and design conceptualization）are part of the synthesis subprocess．That is，the result of the synthesis subprocess is a conceptual design of the prospective product in the form of a sketch or a layout drawing that shows the relationships among the various product components[2]．The major financial commitments needed to realize the product idea are made and the functionality of the product is determined during this phase of the cycle．Most of the information generated and handled in the synthesis subprocess is qualitative and consequently is hard to capture in a computer system．
Once the conceptual design has been developed，the analysis subprocess begins with analysis and optimization of the design．An analysis model is derived first because the analysis subprocess is applied to the model rather than the design itself．Despite the rapid growth in the power and availability of computers in engineering，the abstraction of analysis model will still be with us for the foreseeable future．The analysis model is obtained by removing from the design unnecessary details，reducing dimensions，and recognizing and employing symmetry．Dimensional reduction，for example，implies that a thin sheet of material is represented by an equivalent surface with a thickness attribute or that a long slender region is represented by a line having cross-sectional properties．Bodies with symmetries in their geometry and loading are usually analyzed by considering a portion of the model．In fact，you have already practiced this abstraction process naturally when you analyzed a structure in an elementary mechanics class．
Once a design has been completed，after optimization or some tradeoff decisions，the design evaluation phase begins．Prototypes may be built for this purpose．The new technology called rapid prototyping is becoming popular for constructing prototypes．This technology enables the construction of a prototype by deposition layers from the bottom to the top．Thus it enables the construction of the prototype directly from its design because it requires basically the cross-sectional data of the product．If the design evaluation on the prototype indicates that the design is unsatisfactory，the process described is repeated with a new design．
参考译文：
设计过程所涉及的活动大体上分为两类综合和分析。如图10-1所示，原始设计活动，如设计需求的认定，设计规格说明的规划，根据收集的相关设计信息进行可行性研究以及设计概念化等，都属综合子过程部分；即综合子过程的结果是各个产品部件间的关系以草图或布局图的形式来表示的所期望产品的概念设计。用于实现该产品理念的主要财政承诺和产品功能都在产品周期的这一阶段确定。在综合子过程中产生和处理的大多数信息是定性的，因此在计算机系统中很难得到。
一旦概念设计形成，分析子过程就开始对设计进行分析和优化。首先要导出一个分析模型，因为分析子过程适用于该模型而非设计本身。尽管在工程上，计算机的能力和可用性迅速提高，但对分析模型的抽象依然会在可预见的未来仍有待人去完成。分析模型可从设计中去除不必要的细节，缩小尺寸和识别并使用对称性。例如：尺寸缩小表示一张薄的材料由具有厚度属性的等效曲面来代表，或一个细长区域由具有截面特性的线段来表示。在几何和负荷上具有对称性的物体通常用模型的某一部分进行分析。实际上，在初等机械课程上对一个结构进行分析时，早就实践过这种自然的抽象过程。
一旦设计完成，在经过优化或一些权衡制定之后，就开始了设计评价阶段。为此目的可进行原型制作。一种用于构建原型称之为原型速成的新技术现已非常普及。这种技术可通过从底到顶层层地构建原型，由于它可以根据设计直接构建原型，因此它只需要产品的截面数据即可。如果在原型上的设计评价表明这种设计不尽人意，那么，就以新的设计重复进行上述过程。
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