quasipériodiques

Quasipériodiques refers to a property of certain sequences or functions that exhibit a degree of order but lack true periodicity. Unlike periodic sequences that repeat exactly after a fixed interval, quasirepetitive patterns do not exhibit this exact repetition. Instead, they display a structure that is "almost" regular, with elements appearing in a discernible but not perfectly predictable manner.

This concept arises in various scientific disciplines, particularly in mathematics and physics. In mathematics, quasicrystals are a prominent example where atomic arrangements exhibit a long-range order but lack translational symmetry, meaning the pattern does not repeat identically when shifted by any arbitrary distance. This leads to diffraction patterns that are sharp, like those of crystals, but with symmetries that are forbidden in traditional crystallography.

In physics, quasirepetitive phenomena can be observed in systems that are driven by multiple incommensurate frequencies. When two or more periodic forces with frequencies that are not simple integer multiples of each other interact, the resulting combined behavior can be quasirepetitive. This means the combined system will never return to its exact initial state, but it will closely approximate it periodically. The study of such systems is crucial for understanding complex dynamics in fields like fluid mechanics and condensed matter physics. The term "quasipériodique" is the French equivalent of "quasirepetitive" or "quasicrystalline" in this context.