A series-parallel hydraulic hybrid system applied to public buses is put forward,and parameters of key components are analyzed and determined.Energy management strategy based on logic threshold is designed which is aimed at efficient operation of the overall system considering the operational characteristic of the components and taking the curves of engine,hydraulic pump/motor and hydraulic pump as the main design basis;regenerative control strategy which makes regenerative brake system and frictional brake system work harmoniously is designed to raise recovery rate of regenerative brake energy.System dynamic modeling and simulation results show that the energy control strategy designed here is able to adapt system to changes of working condition and switch the operating mode reasonably.The regenerative braking control strategy is effective in raising the utilization of energy and improving fuel economy.

为了得到负阻值性质的电路元件，采用正电阻与运算放大器进行搭建的方法。对搭建构成的负电阻和负电阻的串并联连接以及负电阻和正电阻的串并联连接进行了理论推导和Multisim仿真实验，两种方法的结果一致且证明搭建构成的电路元件具有负电阻的特性。给出了一个负电阻的应用实例。得出了在存在负电阻的电阻串并联等效变换中。负电阻的处理方法与正电阻一致的结论：