PHYSICAL REVIEW E, cilt.61, sa.3, ss.2569-2578, 2000 (SCI İndekslerine Giren Dergi)
This work presents a general framework for assessing the quality and robustness of control over a deterministic system described by a state vector x(t) under external manipulation via a control vector u(t). The control process is expressed in terms of a cost functional, including the physical objective, penalties, and constraints. The notions of optimality and robustness are expressed in terms of the sign and the magnitude of the cost functional curvature with respect to the controls. Both issues may be assessed from the eigenvalues of the stability operator S whose kernel K(t,tau) is determined by <(delta u(t))over bar>/<(delta u(tau))over bar> for t(0)