RESUMEN
External disturbances and packet dropouts will lead to poor control performance for the wastewater treatment process (WWTP). To address this issue, a robust model-free adaptive predictive control (RMFAPC) strategy with a packet dropout compensation mechanism (PDCM) is proposed for WWTP. First, a dynamic linearization approach (DLA), relying only on perturbed process data, is employed to approximate the system dynamics. Second, a predictive control strategy is introduced to avoid a short-sighted control decision, and an extended state observer (ESO) is used to attenuate the disturbance effectively. Furthermore, a PDCM strategy is designed to handle the packet dropout problem, and the stability of RMFAPC is rigorously analyzed. Finally, the correctness and effectiveness of RMFAPC are verified through extensive simulations. The simulation results indicate that RMFAPC can significantly reduce IAE by 0.0223 and 0.1976 in two scenarios, regardless of whether the expected value remains constant or varies. This comparison to MFAPC demonstrates the superior robustness of RMFAPC against disturbances. The ablation experiment on PDCM further confirms its capability in handling the packet dropout problem.
RESUMEN
Objective: The intracranial venous system plays an important role in ensuring blood circulation and a stable blood supply to the fetal brain. In the present study, a cross-sectional area of the fetal straight sinus was quantitatively evaluated by fetal magnetic resonance imaging (MRI) to explore the method's clinical value. Methods: The clinical and MRI data of 126 normal fetuses in mid-to-late stage pregnancies were retrospectively analyzed. The "dominant" sequence of the fetal straight sinus was selected, and the cross-sectional area of the lumen was measured at each gestational age to obtain the normal range at different ages and to analyze the developmental pattern and characteristics of the fetal straight sinus. Results: There were statistically significant differences in the cross-sectional area of the fetal straight sinus among different gestational ages (P < 0.05). The cross-sectional area of the fetal straight sinus was positively correlated with gestational age (coefficient of determination = 0.6892, P < 0.05). That is, the cross-sectional area of the fetal straight sinus grew with increasing gestational age, and the regression equation was y = 0.27 x - 2.14 (P < 0.05). Additionally, there were five fetuses with cerebral venous abnormalities, including four with heart failure and one with venous sinus thrombosis. Conclusion: Quantitative measurement of a cross-sectional area of the fetal straight sinus by MRI enhanced understanding of the anatomical features and developmental pattern of fetal cerebral veins and provided a reference for the clinical diagnosis of related diseases and investigation concerning pathogenesis.