Traffic-light signalling and operation to a double red light. Tianjin in the People's Republic of China has two very special systems of traffic lights, in use since : One system is where there is a horizontal bar in a specific colour, with the colour changing and the bar shrinking. The shrinking bar indicates the time remaining in that colour. The colour itself is either red (stop), yellow or green (go). A blinking green one-third-full bar means "reduce speed now", and a blinking yellow full-bar indicates "proceed with caution". When lights of this system turn from green to red, the diminishing green bar will flash
Ship motions or "roll axis", is an imaginary line running horizontally through the length of the ship, through its centre of gravity, and parallel to the "waterline". A roll motion is a side-to-side or port-starboard tilting motion of the superstructure around this axis. There are three special axes in any ship, called vertical, transverse and longitudinal axes. The movements around them are known as roll, pitch and yaw. There are methods for both passive and active motion stabilization used in some designs. They include static hull features such as skegs and bilge keels, or active mechanical devices like counterweights, antiroll tanks and