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In this study, two-dimensional (2D) and three-dimensional (3D) numerical calculations were conducted to investigate the aerodynamic characteristics, especially the unsteady aerodynamic characteristics and attitude stability of a bio-inspired corrugated airfoil compared with a smooth-surfaced airfoil (NACA2408 airfoil) at the chord Reynolds number of 4000 to explore the potential applications of non-traditional, corrugated dragonfly airfoils for micro air vehicles (MAVs) or micro-sized unmanned aerial vehicles (UAVs) designs. Two problem settings were applied to our numerical calculations. First, the airfoil was fixed at a constant angle of attack to analyze the aerodynamic characteristics and the hydrodynamic moment. Second, the angle of attack of airfoils was passively changed by the fluid force to analyze the attitude stability. The current numerical solver for the flow field around an unsteady rotating airfoil was validated against the published numerical data. It was confirmed that the corrugated airfoil performs (in terms of the lift-to-drag ratio) much better than the profiled NACA2408 airfoil at low Reynolds number R e = 4000 in low angle of attack range of 0 ∘ – 6 ∘ , and performs as well at the angle of attack of 6 ∘ or more. At these low angles of attack, the corrugated airfoil experiences an increase in the pressure drag and decrease in shear drag due to recirculation zones inside the cavities formed by the pleats. Furthermore, the increase in the lift for the corrugated airfoil is due to the negative pressure produced at the valleys. It was found that the lift and drag in the 2D numerical calculation are strong fluctuating at a high angle of attacks. However, in 3D simulation, especially for a 3D corrugated airfoil with unevenness in the spanwise direction, smaller fluctuations and the smaller average value in the lift and drag were obtained than the results in 2D calculations. It was found that a 3D wing with irregularities in the spanwise direction could promote three-dimensional flow and can suppress lift fluctuations even at high angles of attack. For the attitude stability, the corrugated airfoil is statically more unstable near the angle of attack of 0 ∘ , has a narrower static stable range of the angle of attack, and has a larger amplitude of fluctuations of the angle of attack compared with the profiled NACA2408 airfoil. Based on the Routh–Hurwitz stability criterion, it was confirmed that the control systems of the angle of attack passively changed by the fluid force for both two airfoils are unstable systems.

Due to the lack of body stability of emergency rescue vehicles, their attitude stability is insufficient and they are unable to realize working while driving, resulting in low rescue efficiency. Aiming at the water tower fire truck, which is equipped with an active suspension system, the vehicle attitude stability is studied. First, combined with the active suspension system and spray system, a 13-DOF integrated dynamic model for the water tower fire truck is established. Using the model-assisted active disturbance rejection control method, the controllers are designed for the vertical displacement, pitch angle, and roll angle of the vehicle attitude. Then, the computer simulation is carried out to verify the effectiveness of this control method. Finally, the water spray obstacle crossing experiment is carried out with a JP32G water tower fire truck. The results show that when the vehicle runs over the triangular obstacle on one side and two sides in the integrated spray-active suspension mode, the peak–peak values of body pitch angle and roll angle are reduced by 10.9% and 23.2%, and 23.7% and 16.3%, respectively, compared with the passive hydro pneumatic suspension.

Despite the increasing popularity of including attitudinal and perceptual indicators within discrete choice models, debate endures as to whether there exists a causative relationship between attitudes and behaviour, resulting in what has been termed the attitude behaviour gap. In attempt to understand its origins, attitudes have been categorised as global or localised according to whether or not they are related to a specific time, context and action. Under this framework, global attitudes (GA) typically result in poor predictions of specific overt behaviours, whilst attitudes toward behaviour, or localised attitudes (LA), tend to be better predictors of actual outcomes. Also, attitude strength, measured as the accessibility in memory, plays a determinant role in reducing the gap between attitudes and behaviour, with “memory-based” attitudes having a better prediction of overt behaviours than short-term attitudes constructed “on the spot”. The specific focus of the current paper is to examine the temporal stability and the nature of attitudes, being it critical to transportation planning and research considering the controversial link between attitudes and behaviour. An in depth analysis of the different types of attitudes towards satisfaction for train trips reveals that GAs and LAs provide moderately different outcomes. Also, a memory effect has been found, suggesting the connection between attitudes created on the spot and those stored in memory. Further, both GAs and LAs impact significantly on individual preferences. Finally, the omission of LAs, which are rarely employed within transport literature, may potentially lead to inconsistent estimates, as their contribution in explaining the choice will be absorbed by the error term.

A robust fixed-time control framework is presented to stabilize flexible spacecraft’s attitude system with external disturbance, uncertain parameters of inertia, and actuator uncertainty. As a stepping stone, a nonlinear system having faster fixed-time convergence property is preliminarily proposed by introducing a time-varying gain into the conventional fixed-time stability method. This gain improves the convergence rate. Then, a fixed-time observer is proposed to estimate the uncertain torque induced by disturbance, uncertain parameters of inertia, and actuator uncertainty. Fixed-time stability is ensured for the estimation error. Using this estimated knowledge and the full-states’ measurements, a nonsingular terminal sliding controller is finally synthesized. This is achieved via a nonsingular and faster terminal sliding surface with faster convergence rate. The closed-loop attitude stabilization system is proved to be fixed-time stable with the convergence time independent of initial states. The attitude stabilization performance is robust to disturbance and uncertainties in inertia and actuators. Simulation results are also shown to validate the attitude stabilization performance of this control approach.

In this paper, we address simultaneous control of a flexible spacecraft’s attitude and vibrations in a three-dimensional space under input disturbances and unknown actuator failures. Using Hamilton’s principle, the system dynamics is modeled as an infinite dimensional system captured using partial differential equations. Moreover, a novel adaptive fault tolerant control strategy is developed to suppress the vibrations of the flexible panel in the course of the attitude stabilization. To determine whether the system energies, angular velocities and transverse deflections, remain bounded and asymptotically decay to zero in the case wherein the number of actuator failures is infinite, a Lyapunov-based stability analysis is conducted. Finally, extensive numerical simulations are performed to demonstrate the performance of the proposed adaptive control strategy.

This study investigates the modelling and attitude behaviors of a partial-spin spacecraft following mass separation. A dimensionless dynamic model of the spacecraft’s attitude motion is developed and validated against common dynamic simulation software. The effects of key configuration parameters—separated mass, eccentricity, separation arm length, and platform mass—on attitude stability are analyzed, revealing their influence on spin axis deviation angle. These findings provide guidance for the dynamic analysis and configuration design of such spacecraft.

The performance of attitude stabilization control algorithms for rigid spacecraft can be limited by disturbances. In this paper, the global finite-time attitude stabilization problem with disturbances is investigated and handled by constructing a second-order sliding mode controller. Firstly, a virtual controller based on set stabilization idea is constructed to globally finite-time stabilize the system. Then, a relay polynomial second-order sliding mode controller is constructed to guarantee that the tracking error toward the virtual controller will converge to zero in finite-time. Finite-time Lyapunov theory is applied to support the proof and stability analysis. The global finite-time stability holds even with bounded disturbances. The effectiveness and feasibility of the controller are illustrated by the numerical simulations.

Background Although past studies have identified factors associated with individual perceptions of vaccination, limited attention has been paid to the role of personality in individual attitudes toward vaccination. This study aimed to evaluate the effect of personality as measured by the Big Five personality traits on individual attitudes toward vaccination using a nationally representative survey in the United States. Methods A cross-sectional study was conducted with a sample of 3276 American citizens who were aged 18 and above and lived in 50 U.S. states and Washington D.C. from the American National Election Studies. The survey was collected through face-to-face and online interviews using structured questionnaires in 2016. The multistage stratified cluster sampling procedure was used for face-to-face interview, whereas the USPS DSF was used to select the sample for online interview. Multivariable ordinal logistic regression was used to assess how personality traits (extraversion, agreeableness, conscientiousness, emotional stability, and openness to experience) as main explanatory variables influence the outcome variables – individual attitudes toward health benefits of vaccination and support for school vaccination. Results More than two-thirds of respondents perceive health benefit of vaccination and support vaccination requirements for school entry, whereas about one-tenth of respondents have safety concerns about vaccination and oppose the vaccination requirements. After adjusting for ideology, insurance status, and demographic variables, the traits of agreeableness, conscientiousness and emotional stability remain significantly associated with attitude toward vaccination; conscientiousness is significantly associated with support for school vaccination. The odds of reporting health benefits of vaccination associated with one-point increase in agreeableness, conscientiousness and emotional stability are 1.05 (95% confidence intervals [CI] = 1.01–1.08), 1.05 (95% CI = 1.02–1.09) and 1.03 (95% CI = 1.00–1.06), respectively. For a one-point increase in conscientiousness, the odds of supporting school vaccination increase by 1.08 (95% CI = 1.05–1.12). Conclusions People high in agreeableness, conscientiousness and emotional stability are more likely to regard vaccination as beneficial, whereas those high in conscientiousness are more likely to support school-based vaccine requirement. This study highlights the importance of personality in shaping individual attitudes toward vaccination. More research is needed to understand the role of personality in individual health attitudes and behavior.

Coaxial twin-rotor UAVs face significant attitude stabilization challenges due to complex rotor flow fields and sensitivity to external disturbances. To address this, an ADRC parameter tuning method based on the BAS-WOA hybrid algorithm is proposed. A dynamic model of the UAV is established via Newton-Euler equations, and the ADRC controller (including TD, ESO, and NLSEF) with six key parameters is designed. The hybrid algorithm combines BAS’s rapid global exploration with WOA’s local refined search to avoid local optima. MATLAB simulations show the BAS-WOA algorithm converges in less than 10 iterations with more stable parameter tuning. This method effectively improves the UAV’s control accuracy and anti-disturbance ability.

This is a study of adaptive constraint attitude control for a flexible spacecraft in the presence of inertia uncertainties, unknown disturbance, actuator saturation and faults. The proposed controller is designed by incorporating a Prescribed Performance Control (PPC) and fixed-time sliding mode control. First, a novel Nonsingular Fast Fixed-time Sliding Surface (NFFTSS) is introduced. Not only is the settling time independent of initial conditions, but also it is shorter than existing fixed-time attitude controls. Second, different from the conventional complex PPCs in the literature, a simple structure attitude controller is proposed to satisfy the transient and steady-state performance is proposed through a novel log-type PPC. An inherently continuous adaptive switching control is then presented in order to avoid the a priori not to require accurate information of the fault occurrence. Numerical simulations demonstrate that the proposed controller successfully accomplishes attitude control with high attitude pointing accuracy and stability.