RESUMO
The OH radical concentration was measured by applying tunable diode laser absorption spectroscopy, which is an in situ optical method. An optical absorption region (P7.5ff transition at 1502.7 nm) of the OH radical was selected in the near-infrared range to measure the OH radicals quantitatively in premixed CH4/air flames. An improved direct absorption spectroscopy (DAS) method based on wavelength division multiplexing was proposed to extract the H2O absorption signal that interfered with the OH light absorption signal, and the integral intensity of OH* chemiluminescence was compared to the measured OH radical concentration based on the improved DAS method.
RESUMO
This paper focuses on the autonomous recovery maneuvers of an unknown underactuated practical catamaran, which returns to its initial position corresponding to the man overboard (MOB) by simply adjusting the rate of turn. This paper investigates the completion of model-based path following control for not only the traditional Williamson turn, but also complex recovery routes under time-varying disturbances. The main difficulty of model-based path following control for predicting the hydrodynamic derivatives of a practical catamaran was solved by the approximated calculation of a diagonal matrix. The second key problem of differential calculation for an underactuated model in the case of complex reference trajectories under severe disturbances was investigated. Even though this paper employs a diagonal matrix with unknown nonlinear terms, the experimental test using a small craft with payloads by remote control demonstrated the sway force per yaw moment in turning cases. Adaptive backstepping mechanisms with unknown parameters were proven by the Lyapunov theory as well as the passive-boundedness of the sway dynamics, guaranteeing the stability of sway motion in the case of unavailable sway control. The effectiveness of the algorithms of the guiding concept and error dynamics is demonstrated by the numerical simulations.