  In the paper, several concrete examples, as well as their numerical
simulations, are given to show that parameter identification based on the
so-called adaptive synchronization techniques might be failed if those
functions with parameters pending for identification in coupled systems are
designed to be mutually linearly dependent or approximately linearly dependent
on the orbit in the synchronization manifold. This failure might be emergent
not only when the synchronized orbit is selected to be some sort of equilibrium
or some sort of periodic oscillation, but also when it is taken as some type of
chaotic attractor produced by driving system. This result implies that chaotic
property of driving signal is not necessary to achievement of parameter
identification. The mechanism inducing such a failure, as well as the bounded
property of all trajectories generated by coupled systems, is theoretically
expatiated. New synchronization techniques are proposed to rigorously realize
the complete synchronization and parameter identification in a class of systems
where the nonlinearity is not globally Lipschitz. In addition, parameter
identification are discussed for systems with time delay.
