RESUMO
Flying animals resort to fast, large-degree-of-freedom motion of flapping wings, a key feature that distinguishes them from rotary or fixed-winged robotic fliers with limited motion of aerodynamic surfaces. However, flapping-wing aerodynamics are characterized by highly unsteady and three-dimensional flows difficult to model or control, and accurate aerodynamic force predictions often rely on expensive computational or experimental methods. Here, we developed a computationally efficient and data-driven state-space model to dynamically map wing kinematics to aerodynamic forces/moments. This model was trained and tested with a total of 548 different flapping-wing motions and surpassed the accuracy and generality of the existing quasi-steady models. This model used 12 states to capture the unsteady and nonlinear fluid effects pertinent to force generation without explicit information of fluid flows. We also provided a comprehensive assessment of the control authority of key wing kinematic variables and found that instantaneous aerodynamic forces/moments were largely predictable by the wing motion history within a half-stroke cycle. Furthermore, the angle of attack, normal acceleration and pitching motion had the strongest effects on the aerodynamic force/moment generation. Our results show that flapping flight inherently offers high force control authority and predictability, which can be key to developing agile and stable aerial fliers.
Assuntos
Voo Animal , Asas de Animais , Animais , Fenômenos Biomecânicos , Modelos Biológicos , Simulação de Ambiente EspacialRESUMO
The objective of this study is to investigate rheumatologic manifestations of hepatitis B and C and their relation with viral load and degree of hepatic fibrosis. Thirty-six HBV and 36 HBV patients were included. Liver biopsy was performed for all participants. We detected arthralgia 53-50%, myalgia 58-61% and fatigue 64-81% in HBV and HCV groups in order. All manifestations did not differ between groups significantly. Pain intensity was higher in HCV group (P = 0.023). Arthralgia is associated with viral load of the patients in both groups (P = 0.000 and P = 0.001). Viral load and fatigue are correlated in both groups (P = 0.000 and P = 0.001). There is a considerable relation between inflammation and arthralgia (P = 0.000) and myalgia (P = 0.033). We conclude that rheumatologic manifestations are common both in HBV and HCV and related with viral load and fibrosis.