Analysis of control programs and climb paths of the hypersonic first stage of an aerospace system

Control programs and flight paths of the hypersonic first stage of an aerospace system in climb with acceleration to hypersonic velocity are analyzed. Two approaches to determining the control programs and flight paths are identified: the "traditional" approach and the "optimization" one. The "traditional" approach implies specifying a typical mission profile with max-q and peak heat flux. In the case of the "optimization" approach the problem of propellant mass minimum is stated and solved using the method of Pontryagin’s maximum principle. It concerns the mass of propellant consumed in hypersonic acceleration for various terminal flight path angles. Optimal control programs and optimal flight paths are determined. Those meeting the max-q and peak heat flux requirements are selected. The results of modeling the motion of a hypersonic booster with typical and optimal angle-of-attack schedules corresponding to the "traditional" and "optimization" approaches are presented and discussed. It is established that less propellant is consumed in the case of optimal control, which is accounted for by more efficient use of the hypersonic booster's aerodynamic performance due to direct control of the angle of attack.

Review of Remanufacturing for Automotive Components

Based on the concept of the remanufacturing for automotive components, the significance of implementing the remanufacturing was analyzed in this paper. And then the advanced technologies of automotive remanufacturing were focused on with some examples, such as the electro-brush plating technology, high-speed arc spraying technology, hypersonic velocity plasma spraying technology, scratch fast fill technology, and so on. In the end the conclusion was educed that the automotive remanufacturing is significant to the sustainable development of the society economy and the environmental protection, so the implementation is imperative under the situation.

Acoustic Properties of Ho2Si2O7 Single Crystal Investigated by Brillouin Light Scattering

Micro-Brillouin light scattering experiments were performed on flux grown D-type (monoclinic, P21/c) Ho2Si2O7 single crystal from room temperature to 850 K. Both the hypersonic velocity (VLA) and related elastic constant (c33) of the longitudinal acoustic phonons propagating along 001-direction showed a small dispersion at T565 K whereas the same could not be observed clearly in attenuation/damping. The overall temperature dependent behavior of elastic constant and hypersonic velocity was attributed to the lattice anharmonicity of the crystal in the investigated temperature range.