What does VTi mean?

What does VTi mean?

The VTi Engine (Variable Valve Lift and Timing injection) is a car engine created jointly by both PSA Peugeot Citroën and BMW Group from the BMW VALVETRONIC concept.

What is the difference between phase velocity and group velocity?

The group velocity is positive (i.e., the envelope of the wave moves rightward), while the phase velocity is negative (i.e., the peaks and troughs move leftward). The group velocity of a wave is the velocity with which the overall envelope shape of the wave’s amplitudes—known as the modulation or envelope of the wave—propagates through space.

What is the history of group velocity?

The idea of a group velocity distinct from a wave’s phase velocity was first proposed by W.R. Hamilton in 1839, and the first full treatment was by Rayleigh in his “Theory of Sound” in 1877. For light, the refractive index n, vacuum wavelength λ0, and wavelength in the medium λ, are related by

What is the group velocity of a wave?

The group velocity of a wave is the velocity with which the overall envelope shape of the wave’s amplitudes—known as the modulation or envelope of the wave—propagates through space.