帮忙确认下这段英文中某些词的具体含义~

帮忙确认下这段英文中某些词的具体含义~
这篇文章的题目是：A dual-stage functional modelling framework with multi-level design knowledge for conceptual mechanical design（我的译文：一个为概念上的机械设计服务的双重级水平设计的功能模型构架）
As has already been mentioned,the functional objects stored in the functional object library are represented using an object-oriented scheme.With the inheritance mechanism from OO technology,the classes representing mechanical functions are
organized into three tiers of a hierarchy,i.e.from generic As has already been mentioned,the functional objects stored in the functional object library are represented using an object-oriented scheme.With the inheritance mechanism from OO technology,the classes representing mechanical functions are
organized into three tiers of a hierarchy,i.e.from generic function to embodiment function (the complete list of classes de.ning the functional objects are given in the
Appendix).
First tier—topfunc:defining the generic functional objects,whose attributes(variables) and methods are required by all functional objects.
Second tier—permfunc,asemfunc,manufunc,markfunc,mainfunc:defining five basic types of mechanical functions; namely,performance function,assembly function,manufacturing function,marketing function and maintenance function (Deng et al.1998).These function classes inherit attributes and
methods from the class topfunc.
Third tier—fmffunc:defining embodiment mechanical functions,which have associated physical structures.This class inherits attributes and methods from its upper class permfunc.
请问：
1.我那实在不是很象样.文中（其他地方相同情境）曾多次出现knowledge 这个词,翻译成什么好?理论?原理?知识好象不大通顺.
2.Second tier中的“mechanical functions; namely,performance function,assembly function,manufacturing function,marketing function and maintenance function ”是翻译成**功能,还是**函数!
3.如果有可能的话,请帮忙全部翻译下,一段也行~

理论,学说 theory
原理 principle
function在那里应该翻译成功能
翻译就不用了,太长了