The piezoelectric properties of lead zirconate titanate [Pb(Zr,Ti)O 3 or PZT] ceramics could be enhanced by fabricating textured ceramics that would align the crystal grains along specific orientations. We present a seed-passivated texturing process to fabricate textured PZT ceramics by using newly developed Ba(Zr,Ti)O 3 microplatelet templates. This process not only ensures the template-induced grain growth in titanium-rich PZT layers but also facilitates desired composition through interlayer diffusion of zirconium and titanium. We successfully prepared textured PZT ceramics with outstanding properties, including Curie temperatures of 360°C, piezoelectric coefficients d 33 of 760 picocoulombs per newton and g 33 of 100 millivolt meters per newton, and electromechanical couplings k 33 of 0.85. This study addresses the challenge of fabricating textured rhombohedral PZT ceramics by suppressing the otherwise severe chemical reaction between PZT powder and titanate templates.

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Supercavitating vehicles have special characteristics from traditional underwater vehicles because of supercavitation. The motion of the vehicle tends to be unstable, and the dynamics of it is nonlinear and strongly coupled. Due to the time-varying factors, delay-dependent behavior and unmodeled dynamics of system, a simplified model is developed. For the supercavitating vehicle with the mismatched uncertainties, continuous sliding mode controller is designed, with an adaptive technology which is used to estimate the unknown upper bound of mismatched uncertainties. Meanwhile, upper bound of parameter uncertainties is not required. Simulation results show the effectiveness of the controller designed in the paper.

A new concept of control accelerated motion of supercavitating vehicle is present. Before reaching a constant cruising speed of 100 m/s supercavitating vehicle is process of accelerated motion. In order to explore dynamic model and control challenges associated with the longitudinal accelerated motion of supercavitating vehicles, memory effect of the cavity and its influence on shape of cavity are researched based on the principle of cavity expansion independence. Efficiency of the fin as its immersion depth changes while the vehicle is traveling underwater is researched. A gain schedule controller is designed to stabilize the dive-plane dynamics during accelerated motion of supercavitating vehicle