In order to improve the safety of heavy-duty vehicles in the steering process, this paper proposes an active front wheel steering control strategy based on the sliding mode variable structure control. With this strategy in mind, an active steering controller is designed. A simplified vehicle dynamics model with two degrees of freedom and a model for a three-axle commercial vehicle are established. The co-simulation platform is built with TruckSim and Simulink, and the hardware-in-loop experiment is carried out. Under different working conditions and at different speeds, the steering stability analysis of the vehicle with or without the active steering controller is carried out. Based on this, the sensitivity analysis of the active steering influencing factors of the sliding mode variable structure control is carried out. The experimental results show that this controller strategy has a good adaptability under different working conditions.
With a finite element model, the dynamic response of the catenary riser of deep-sea mining systems under the action of the ocean current and the motion of the surface vessel is simulated. The results show that the maximum equivalent stress and the maximum displacement of the catenary riser change periodically with a phase difference of half a period between them. When the surface vessel moves to the highest position, the displacement of the catenary riser reaches the maximum. The maximum equivalent stress and the maximum displacement of the catenary riser increase with the increase of the displacement amplitude of the surface vessel and decrease with the increase of the period. In addition, the effect of the displacement and the period of the motion of the surface vessel on the equivalent stress of the catenary riser is greater than that on the displacement.
The inhaled nanoparticles (NPs) are first met by the biological barrier inside the alveolus known as the lung surfactant (LS). They can reach deep into the lung and interfere with the biophysical properties of the lung components. The interaction mechanisms of the gold nanoparticles (AuNPs) with the LS monolayer and the consequences of the interactions on the lung function are not well understood. Coarse-grained molecular dynamics simulations are carried out to study the interaction between the AuNPs and the LS monolayers at the nanoscale. It is observed that the presence of the AuNPs deforms the monolayer structure, changes the biophysical properties of the LS monolayer, and the results also indicate that the AuNPs with different shapes have different effects on the LS monolayer. These findings could help to identify the possible consequence of the airborne NPs inhalation.
This paper presents a simple method to estimate and optimize the maximum launch capability of low Earth orbit (LEO) with different launch modes and trajectories, combined with trajectory optimization. The numerical calculation is carried out for the CZ-7 rocket, to analyze the specific effect and the characteristics of the optimal launch trajectory when launching with the cross-feed technology. The results show that the maximum launch capability of the LEO can be increased by 3 t (about 20%) and the maximum axial acceleration during the launch can be reduced by nearly 50% if for the CZ-7, the propellant cross-feed technology is applied in the launching process. With the help of the propellant cross-feed technology, the launch capability of such lift launch vehicle can be greatly improved.
In this study, the growth of an incompressible Newtonian drop from a vertical circular capillary tube in the presence of surfactant is analyzed. The flow is assumed to be axisymmetric and can be reduced to a spatially one-dimensional system by using the Taylor expansion and the lubrication approximation. The finite difference method combined with a coordinate transform is adopted for the numerical simulation. The results show that the existence of the surfactant will promote the breakup process of the drop, and prolong the limit length. Furthermore, the surfactant concentration has a more critical influence on the interface shapes than the surfactant activity.
The cabin door openings are usually arranged in the fuselage for civil aircraft, resulting in fuselage stiffness discontinuity. In view of the structural stiffness and the transmission of the load, the paper studies the opening structure of the fuselage: clarifying the factors affecting the stiffness of the opening structure and optimizing the opening angle and the size of the reinforcing structure. The above research shows the direction and the method of the design and the reinforcement of the opening structure in the preliminary design stage of the opening structure of the aircraft fuselage.