A gas turbine engine has a pressure ratio of 10, and the intake air is at 90 kPa and 280K. Both the compressor and turbine have an isentropic efficiency of 100% and a regenerator with an effectiveness of 0.8 is used. The highest temperature in the cycle is 1500K. Please determine: (a) the net work output, (b) the thermal efficiency, and (c) the back work ratio. (d) Draw and label the T-s diagram.