A small five-cylinder CI automobile engine operates with a variable valve timing control system without a camshaft. At operational speed of 3500rpm the intake valve opens 32deg bTDC and closes 57deg aBDC. The exhaust valve opens 52deg bBDC and closes 21deg aTDC. When the engine is idling at 400rpm the intake valve opens 12deg bTDC and closes 18deg aBDC. The exhaust valve opens 21deg bBDC and closes 8deg aTDC. Calculate:
a) Valve overlap in crank angles for operational speed and for idle speed;
b) Valve overlap in real time for operational speed and for idle speed;