Nonlinear robust H-infinity filtering for a class of uncertain systems via convex optimization

A new approach for robust H-infinity filtering for a class of Lipschitz nonlinear systems with time-varying uncertainties both in the linear and nonlinear parts of the system is proposed in an LMI framework. The admissible Lipschitz constant of the system and the disturbance attenuation level are maximized simultaneously through convex multi-objective optimization. The resulting H-infinity filter guarantees asymptotic stability of the estimation error dynamics with exponential convergence and is robust against nonlinear additive uncertainty and time-varying parametric uncertainties. Explicit bounds on the nonlinear uncertainty are derived based on norm-wise and element-wise robustness analysis.     

Preparation, characterization and photocatalytic activity of TiO2/polyaniline core-shell nanocomposite

Polyaniline (PANI) as a promising conducting polymer has been used to prepare polyaniline/TiO₂ (PANI/TiO₂) nanocomposite with core-shell structure as photocatalyst. Titanium dioxide (TiO₂) nanoparticles with an average crystal size of 21?nm were encapsulated by PANI via the in situ polymerization of aniline on the surface of TiO₂ nanoparticles. FT?CIR, UV-Vis-NIR, XRD, SEM and TEM techniques were used to characterize the PANI/TiO₂ core-shell nanocomposite. Photocatalytic activity of PANI/TiO₂ nanocomposite was investigated under both UV and visible light irradiations and compared with unmodified TiO₂ nanoparticles. Results indicated deposition of PANI on the surface of TiO₂ nanoparticles which improved the photocatalytic activity of pristine TiO₂ nanoparticles.