A method includes: (1) applying stimulations to a system, wherein applying the stimulations includes modulating, over time, characteristics of the stimulations； (2) measuring a time-varying response of the system to the stimulations； (3) fitting the time-varying response of the system into a model of the system； and (4) using the model of the system, identifying an optimized combination of characteristics of the stimulations to yield a desired response of the system.
