A self-healable and reprocessable reclaimed rubber is developed by re-crosslinking waste natural powders with polysulfide via a thiol–ene reaction.

Purpose This study aims to investigate an adaptive notch filtering approach suppress the effects of elastic vibration on attitude control flexible launch vehicles. Design/methodology/approach First, dynamics model vehicle and baseline PID controller are presented. Furthermore, frequency identification algorithm based a second-order filter is developed identify frequency. Finally, holder update filter. Findings The proposed with can accurately, appropriately vehicles effectively....

In in situ leaching, fine particles can be stripped and transported with the leach solution, significantly altering particle size distribution pore structure of each layer rare earth ore body. this study, water magnesium sulfate were used as leaching agents. Based on indoor column experiments, gradation tests, study investigates analyzes patterns migration changes ores varying contents under conditions. The results indicate that during process, degree change follows order upper > middle...

The surface precision of an antenna reflector can be improved using the actuation piezoelectric materials to obtain a high-performance space antenna. In this study, active shape control with piezoceramic (lead zirconate titanate) actuators assembled on ribs is proposed by theoretical and experimental approaches. A finite element model integrated reflector–actuator system established constitutive equations virtual work’s principle. For desired shape, closed-loop iterative method based...

The inverse finite element method (IFEM) is currently one of the most studied methods in field shape sensing, other words, reconstruction displacement a structure from discrete strain measures. current research still insufficient applying IFEM to flexible structures undergoing large deformation that are increasing demand, especially terms computational efficiency. Hence, an element-by-element approach based on absolute nodal coordinate formulation (ANCF) developed paper. Taking plane beam as...

SUMMARY In this paper, the principle of least action and generating functions are used to construct symplectic numerical algorithms for finite dimensional autonomous Hamiltonian systems. The approximate is obtained by approximating generalized coordinates momentums Lagrange polynomials performing Gaussian quadrature. Based on requirements a canonical transformation, different types have been constructed choosing independent variables at two ends time step. symmetric property four proposed in...

The robust H ∞ control for spacecraft rendezvous with a noncooperative target is addressed in this paper. relative motion of chaser and firstly modeled as the uncertain system, which contains orbit parameter mass. Then performance finite time are proposed, controller developed to drive non‐cooperative presence input saturation, measurement error, thrust error. linear matrix inequality technology used derive sufficient condition proposed controller. An illustrative example finally provided...

For the initial value and two-point boundary problems of linear ordinary differential equation, Precise Integration Method (PIM) gives exact solutions in computer accuracy sense. In this paper, basic idea further development PIM are surveyed. problems, PIM, methods for integrating nonhomogeneous term, large scale application time-varying nonlinear system fundamental formula given many fields Finally, relationship between is discussed, which a new angle understanding PIM.

Active shape control for an antenna reflector is a significant procedure used to compensate the impacts of complicated space environment. In this article, physics-guided distributed model predictive (DMPC) framework with input saturation proposed. First, guided by actual physical characteristics, overall structural system decomposed into multilevel subsystems help so-called substructuring technique. For each subsystem, prediction information interaction discretized explicit Newmark- β...

This paper investigates the spacecraft attitude tracking control problem. A quaternion-based adaptive terminal sliding mode controller is proposed to solve this problem in presence of model uncertainties and environmental perturbations. The can drive motion track a time-varying trajectory finite time. An law developed estimate generalized disturbances. Numerical simulations are finally provided illustrate performance controller.

The time-delay discrete-time equations are derived directly from the differential vibration for structures in state space, with discrete parameters obtained via precise integration method. Then a vector expansion method is used to transform these into ones which do not contain terms explicitly. Next, order of this system substantially reduced by using balanced reduction form dominant subsystem based on eigenmodes subspace highest controllability. controllers then designed optimal control...

To achieve high-precision shape control of antenna reflectors in the presence model errors, an adaptive method based on feedback error learning algorithm is proposed. First, th...

An improved time-varying optimal controller based on parameter optimization is proposed for the stabilization of spacecraft missions nominal libration-point orbits Sun–Earth system. Because importance weighting matrices in design controller, a genetic algorithm and sequential quadratic programming method, two models (for time-invariant piecewise-constant matrices) are used to determine improve performance controller. Practical presented moving steadily reference orbit. Numerical simulations...

H ∞ full information control method for structural vibration suppression with delay is proposed within a discrete-time framework. Firstly, the continuous-time system equation discretized by precise computation of matrix exponentials. By introducing an appropriate extended state vector, time-delay transformed into standard discrete forms without time delays. Then controller designed based on theory. The consists regular feedback closed-loop and feed-forward compensator which utilizes external...