No abstract

Dichloromethane (DCM) is a toxic pollutant with prolonged persistence in air and water. The work focused on the cultivation of Methylobacterium rhodesiaum H13 which could utilize DCM as the sole carbon source. By comparison and analysis, R2A was chosen as the suitable culture medium for large-scale cultivation. Furthermore, the optimized composition of medium was established on the basis of biomass obtained and the DCM degradation activity of M. rhodesiaum H13, which contained yeast extract 1.5 g/L, peptone 1.5 g/L, glucose 1.5 g/L, sodium pyruvate 0.9 g/L, K2HPO4 0.9 g/L and MgSO4•H2O 0.15 g/L.

System uncertainties and external disturbances are the major causes of the trajectory tracking performance degradation in nonholonomic wheeled mobile robots (NWMRs). In this article, an adaptive fast nonsingular terminal sliding mode dynamic control (AFNTSMDC) method is proposed to provide enhanced robust and finite-time tracking performance for the NWMR. The proposed AFNTSMDC is a systematic design method based upon both the kinematic and dynamic model of the NWMR. The AFNTSMDC controller has a simple form without singularity issue in the control input, which makes it practically implementable. The finite-time stability of the proposed tracking-error function is also proved using the Lyapunov function. Finally, circular trajectory tracking experiments are conducted to validate the robustness and convergence rate of the proposed AFNTSMDC scheme in comparison with the existing methods including classic kinematic control (CKC), robust sliding mode kinematic control (RSMKC), and conventional sliding mode dynamic control (CSMDC) in the presence of uncertainties and external disturbances.