Nikolaos Kazantzis

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A necessary and sufficient condition for the existence of a discrete-time nonlinear observer with linearizable error dynamics is provided. The result can be applied to any real analytic nonlinear system whose linear part is observable. The necessary and sufficient condition derived is associated with the solvability of a nonlinear functional equation. A(More)
or sensor disturbances is proposed. The nonlinear observer design problem is addressed within a similar methodological framework as the one introduced in [8,11] for state estimation purposes only. From a mathematical standpoint, the problem under consideration is addressed through a system of first-order singular PDEs for which a rather general set of(More)
BACKGROUND A number of theories have proposed possible mechanisms that may explain the high rates of comorbidity between posttraumatic stress disorder (PTSD) and persistent pain; however, there has been limited research investigating these factors. OBJECTIVE The present study sought to prospectively examine whether catastrophizing predicted the(More)