今天學到這部分，看到這公式實在讓我滿頭問號：
我不知道怎麼直觀地理解 I_e * w_e' = T_engine - T_turbine，後來找到一個資料才理解
概念上是，我們可以用另一個角度看這公式：
T_turbine = T_engine - I_e * w_e'
Ideally, we want T_turbine = T_engine, which means the torque generated by the engine can be 100% delivered to turbine.
However, T_engine is consumed a little bit because there are some mass in the engine, which consumed the torque generated.
