In most spark ignition engines, a thermodynamic cycle occurs when the piston completes four strokes within the cylinder, and the crankshaft completes two revolutions.

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To get finer shots from a swaying helicopter Segal modified his 360-degree panoramic cameras to spin two revolutions per second, creating a gyro effect whose centripetal force stabilizes the lens.

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In fact, two revolutions are under way.

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Also 81, she's a woman who has lived through two unfinished revolutions and is still campaigning for change.

BBC: Romila Thapar

My read on history is that the great economic revolutions occur when two phenomena come together.

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Two books can be said to have launched revolutions in cooking advice.

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Between the two observations of Gibb and Smith the world was politically wrenched out of its moorings as a result of wars and revolutions.

CENTERFORSECURITYPOLICY: Center For Security Policy