<正>螺杆泵的转子型线比较复杂，其基本齿形采用多种摆线，转子型线方程的推导方法有多种，如解析法、几何法等。用矢量代数推导<135>型三螺杆泵的转子齿形型线方程，包括理论齿形和修正齿形型线参数方程以及参数值范围的完整推导过程，对中间过程和相关概念给出了必要的解释。对比其他方法，用矢量代数进行型线推导，方法简单，过程清晰，便于工程技术人员理解和运用。

This paper aimed to evaluate the efficiency of the wood processing enterprises in Jiangsu province, ascertained the contrast among the different enterprises, and found the approach to improve’ the useless enterprises. By using the DEA model, the authors chosed the labor force,, technology, wood use as the input indexes, and the yield, production value as the output indexes, gave an evaluation of 10 wood processing enterprises which were specially supported by the development programming of Jiangsu’ s poplar industry. The results showed that the efficiency of wood processing leading enterprises was in a suitable situation as a whole, 60% of the enterprises were effective. The pure technology efficiencies of DEA inefficiency enterprises were lower than the scale efficiencies, which indicated that the main reason for the inefficiency was unsuitable resources arrangement. Input redundancies and output lacks were existed in the DEA inefficiency enterprises, while the output indexes were improved highly through adjusting the proportion of input indexes.