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Improved deep convolution neural network (CNN) for the identification of defects in the centrifugal pump using acoustic images

This work addresses the challenging problem of finite-time fault tolerant attitude stabilization control for the rigid spacecraft attitude control system without the angular velocity measurements, in the presence of external disturbances and actuator failures. Consider the severe circumstances with above failures and uncertainties, a novel continuous finite-time Extended State Observer is first established to observe the attitude angular velocity and the synthetic failure simultaneously. Unlike the existing observers, the finite-time methodology and Extended State Observer are utilized, to achieve the finite-time uniformly ultimately bounded stability of the attitude angular velocity and extended state observation errors. Furthermore, a novel continuous finite-time attitude controller is developed by using the nonsingular terminal sliding mode control and super-twisting method. The main feature of this work stems from our use of multiply advanced techniques or methodologies that enables the finite-time stability of the closed-loop attitude control system and the designed control scheme is continuous with the property of chattering restraining. Finally, numerical simulation results are presented to illustrate the effectiveness and fine performances of the finite-time observer and controller for the attitude control system.

Finite-time Extended State Observer based fault tolerant output feedback control for attitude stabilization.

Application of flow control strategy of blowing, synthetic and plasma jet actuators in vertical axis wind turbines

The aerodynamics and flow physics of a NACA 4412 airfoil in ground effect for a wide range of angles of attack from −4 to 20 deg are investigated by numerical simulations. The compressible Reynolds-averaged Navier–Stokes equations and shear-stress transport k-ω turbulence model equations are solved using the finite-volume method. Analyses of the computed results show that the angle of attack versus height (above the ground) plane can be divided into three regions based on the sign of the lift increment value: region I of positive ground effect, and regions II and III of negative ground effect. For low-to-moderate angles of attack, when the ride height is reduced, the airflow is blocked in the convergent passage between the lower surface of the airfoil and the ground, resulting in increase of pressure on the lower surface of the airfoil. As a consequence, the effective angle of attack decreases, and there is less upward deflection of the streamlines, resulting in an increase in pressure on the upper surfac...

Airfoil Aerodynamics in Ground Effect for Wide Range of Angles of Attack

Numerical study of the aerodynamics of a NACA 4412 airfoil in dynamic ground effect

Aerodynamic optimization and mechanism design of flexible variable camber trailing-edge flap

The flow around a wing-in-ground-effect craft flying at α=3  deg and α=9  deg over flat and wavy ground is simulated and investigated by using ANSYS FLUENT, employing the compressible Reynolds-averaged Navier–Stokes equations and the Spalart–Allmaras turbulence model. The sliding mesh technology is used to simulate the relative motion between the wing-in-ground-effect craft and wavy ground. The effects of the wavy ground, flight height, and angle of attack on the aerodynamic characteristics and flowfield are analyzed in detail. The aerodynamic forces are found to be periodic when the wing-in-ground-effect craft flies over wavy ground. The aerodynamic forces over both flat and wavy ground vary with flight height in the same pattern. As the flight height reduces, the lift, drag, and nose-down pitching moment all increase at both angles of attack (α=3  deg and α=9  deg); however, the lift-to-drag ratio increases for all flight heights at α=3  deg, while it first increases and then decreases at α=9  deg. Redu...

Peiqing Liu

Papers

Airfoil Aerodynamics in Ground Effect for Wide Range of Angles of Attack

Numerical study of the aerodynamics of a NACA 4412 airfoil in dynamic ground effect

Aerodynamic optimization and mechanism design of flexible variable camber trailing-edge flap

Numerical Study of Aerodynamics of a Wing-in-Ground-Effect Craft

Aeroacoustic measurement of 30P30N high-lift configuration in the test section with Kevlar cloth and perforated plate