This study develops an active control technology to reduce the incremental dynamic loads of a large four-engine transport airplane flying through a gust field. The mathematical model of the proposed gust-alleviation system features composite structural motions (for example, rigid-body motions, elastic vibrations, and deflections of control surfaces) and unsteady aerodynamic forces induced by the structural motions and the gusts. A clear outline of the procedure is first provided to determine the aeroservoelastic equation of the system. Then, an adaptive feedforward controller that uses the preview information of the gust sensed by an onboard alpha probe is designed to operate the ailerons symmetrically to alleviate the wing-root bending moment induced by the gust. The rigid-body motions due to travelling gusts are also compensated for using symmetrical deflections of the elevators. To solve the problems of weight drift and weight bias that are commonly encountered in adaptive control, the circular leaky least meansquared algorithm is applied to update the weights of the adaptive controller. The simulation results show that a large transport airplane equipped with the proposed gust-alleviation system experiences a significantly lower wing-root bending moment in both stationary and nonstationary gusty environments.

The pyrolysis carbon black (CBp) from waste tires accounts for more than 35% of pyrolysis products. Its poor reinforcing ability and low additional value limit heavily the wide application of thermal pyrolysis in resolving “the black pollution” problem caused by waste tires. In this study, the CBp was upgraded by hybridization with cellulose via ball milling of the CBp and microfibrillated cellulose (MFC). A series of characterizations show that the refinement of the CBp, nanofibrillation of MFC, and hybridization were simultaneously realized under the ball milling. The obtained CBp/nanocellulose hybrid (CNCH) has a bead-chain-like morphology, with the small CBp particles attached tightly to the cellulose nanofibers via hydrophobic and hydrogen-bond interactions. The aqueous suspension of CNCH was spray-dried and compounded with natural rubber (NR). CNCH showed a much higher reinforcing ability than the CBp and ball-milled CBp (mCBp), which was attributed to the unique bead-chain-like morphology, the fine dispersion of CNCH, the interlocking effect, and improved interface interaction between CNCH and NR molecular chains. Especially, NR reinforced by CNCH has very low hysteresis and higher antiabrasion ability, which means CNCH has obvious advantages to be used as reinforcing fillers in tires. The upgrading process is simple, environmentally friendly, and suitable for industrial applications. This work is expected to provide a theoretical basis and technical instruction for the use of the CBp in tires, accelerate the industrialization of pyrolysis, and resolve the black pollution problem.

The aeroelastic model of a folding wing varies with different configurations, so it actually represents a parameter-varying system. Firstly, a new approach based on interpolation of local models is proposed to generate the linear parameter-varying model of a folding wing. This model is capable of predicting the aeroelastic responses during the slow morphing process and is suitable for subsequent control synthesis. The underlying inconsistencies among local linear time-invariant (LTI) models are solved through the modal matching of structural modes and the special treatment of the rational functions in aerodynamic models. Once the local LTI models are represented in a coherent state-space form, the aeroservoelastic (ASE) model at any operating point can be immediately generated by the matrix interpolation technique. Next, based on the present ASE model, the design of a parameterized controller for suppressing the gust-induced vibration is studied. The receptance method is applied to derive fixed point controllers, and the effective independence method is adopted and modified for optimal sensor placement in variable configurations, which can avoid solving ill-conditioned feedback gains. Numerical simulation demonstrates the effectiveness of the proposed interpolation-based modeling approach, and the parameterized controller exhibits a good gust mitigation effect within a wide parameter-varying range. This paper provides an effective and practical solution for modeling and control of the parameterized aeroelastic system.

No abstract

No abstract