Beijing’s metro could quietly carry freight during off-peak hours without new tunnels, a joint timetable–rolling-stock model ...

Beijing's metro system could soon carry express parcels alongside commuters during quiet periods, according to a new operational blueprint published ...

Nonlinear phenomena are phenomena, which, in contrast to a linear system, cannot be explained by a mathematical relationship of proportionality (that is, a linear relationship between two variables).

Nonlinear optics is the study of how intense light interacts with matter. The optical response of a material usually scales linearly with the amplitude of the electric field. At high powers, however, ...