  Results of high-resolution simultaneous multi-frequency 8.1-15.4 GHz VLBA
polarimetric observations of relativistic jets in active galactic nuclei (the
MOJAVE-2 project) are analyzed. We compare characteristics of VLBI features
with jet model predictions and test if adiabatic expansion is a dominating
mechanism for the evolution of relativistic shocks in parsec-scale AGN jets. We
also discuss magnetic field configuration, both predicted by the model and
deduced from electric vector position angle measurements.
