Research of multi-restriction energy management of solid rocket
In order to implement depleted shutdown and improve guidance precision in launching process of a solid rocket, the trajectory energy management approaches should be studied. First, the rocket inserting trajectory problem is described. The real velocity and the required velocity calculating model are given. Second, under the multi-restriction conditions, the spline energy management model is given. Third, required velocity is parameterized by a B-spline function. Take required velocity function to initial conditions, terminal conditions and process conditions, the energy management problem can be solved by an optimum approach. The optimum trajectory can be followed up with trajectory tracking control approach, and make the velocity vector track the required velocity vector. The simulation results show that the terminal and process restrictions are met.
Robust spline-line energy management guidance algorithm with multiple constraints and uncertainties for solid rocket ascending
Abstract For the solid rocket with depletion shutdown system, effective energy management is significant to meet terminal constraints by exhausting excess energy. Several traditional energy management algorithms cannot satisfy the altitude constraint and path constraints are not sufficiently considered. The velocity adjustment capability of these algorithms is limited and the uncertainties are not considered. Based on the on-line programming of velocity capability curve, Spline-Line Energy Management (SLEM) guidance algorithm is proposed. It introduces lateral maneuvers to further consume the available velocity on the basis of longitudinal energy management. After expressing the constraints as several algebraic equations, the closed-loop guidance problem is converted to solving a system of nonlinear equations about the curve parameters in real time. The advantage is that the altitude constraint can be satisfied theoretically. The overload and control variable change rate and amplitude constraints are also considered during the flight by constructing the feasible boundary of velocity capability curve. To improve the robustness, it is further extended by estimating the actual uncertainties. The effectiveness and advantages of SLEM are demonstrated by simulations and comparisons with other energy management algorithms. Simulation results show that the proposed approach can satisfy multiple constraints with high precision under the condition of uncertainties.
Effective adsorption of lead ions using fly ash obtained in the novel circulating fluidized bed combustion technology
Abstract Fly ash was examined for the separation efficiency of Pb2+ ions from water in batch experiments. Fly ash is industrial waste produced from the incineration of sewage sludge by the novel circulating fluidized bed combustion (CFBC) technology and was taken into the experiments. Physical and chemical properties of the material were characterized using several methods, such as fraction analysis, particle size distribution, bulk density, composition, morphology, surface and internal structure by elemental analysis, FT-IR, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis, comprehensive thermal analysis, fly ash texture by BET adsorption isotherms, specific surface area, volume of pores, average pore diameter and pore volume distribution by the BJH method. The influence of pH values on zeta potential of the fly ash surface before and after the adsorption process was conducted. The calculated maximum adsorption capacity of Pb2+ by fly ash reached 51.98 mg/g. The kinetic analysis revealed that the adsorption process is better described by the pseudo-second order equation and it is well fitted to the Freundlich model. In conclusion, fly ash obtained in the CFBC technology is a promising low cost adsorbent for the highly effective recovery of Pb2+ from wastewater.