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In this paper, a high-speed and multi-code-rate low density parity check(LDPC) encoder architecture is proposed for the LDPC codes used in high-speed satellite-ground data transmission of the Chinese high resolution earth observation satellite. Synthesized with Taiwan semiconductor manufacturing company ( TSMC ) 130 nm complementary oxide metal semiconductor (COMS) standard cell library, the designed multi-code-rate LDPC encoder can achieve 1. 6 Gbps throughput in 200 MHz clock frequency, the die size of which is only 5. 495 mm2, and the dynamic power dissipation of which is only 184. 3 mW. Compared with the encoder designed by the traditional LDPC encoder architecture, the memory size, the die size, and the power consumption of the new encoder can be reduced by 18. 52%, 20. 3% and 83. 3% respectively. [ABSTRACT FROM AUTHOR]

The vertical gap flow in the wing-leading-edge of the hypersonic vehicle is investigated in this paper. By analyzing the structure of the leading-edge shield, a geometrical model for the leading-edge gap is established. The flow field structure is obtained by solving the 3D Navier-Stokes equations. The spatial distribution fetature of the 3D vortex induced by gap and corresponding relations between the vortex motion and heat-flux distribution are analyzed. The numerical result shows that in the circular section, the rounding zone of the gap shoulder is a local high heat flux region because of strong 3D-effect normally, and the reattachment of the primary vortex in the gap leads to a "non-normal" high heat flux region on the side wall of the gap. In the straight section, there is a strong vortex region above the gap induced by span wise flow. Because of the effect of vortex separation, the original local high heat flux region at the rounding zone of the gap shoulder turn to local low heat flux region, and local high heat-flux region exists in the side wall region. [ABSTRACT FROM AUTHOR]

A new method for realizing hovering formation in close proximity is investigated with main focus on design of open-loop and close-loop control law. The new method utilizes inter-spacecraft coulomb forces to control relative motion. Hence, plume contamination caused by classical thrusters could be mitigated. First, a mathematical description of the Coulomb hovering formation is established by using polar coordinates. Then, an open-loop control law is provided with respect to the case of elliptic reference orbit. For the case of circular reference orbit, linearized dynamics is obtained by linearizing the model about a nominal hovering formation, and then is used to analyze close-loop feedback control law. Numerical examples are provided to demonstrate the performance of the control laws. The approach proposed in the paper could also be used in other scenario of formation flying in high earth orbit. [ABSTRACT FROM AUTHOR]

Three-dimensional compressible Navier-Stokes equations are numerically solved for the 70° sphere-cone heatshield to predict the hypersonic chemical non-equilibrium aeroheating with catalytic effects. Numerical results show that a substantive amount of inflow gas dissociates in the shock layer, which causes chemical non-equilibrium flow with remarkable high-temperature real-gas effect, particularly near the stagnation. The surface catalysis markedly influences the total heating load, and the heatfluxes for non- and fully catalytic walls are predicted to bear the lowest and highest aeroheating bounds. The determination of O2 and CO2 recombination is expected to be the significant sources of the catalytic heating, and the characterization of the catalytic mechanism of the thermal protection materials is needed so as to precisely predict the Mars entry aeroheating. [ABSTRACT FROM AUTHOR]

As sensor fault on spacecraft may lead to state estimation error, a new method based on evidence theory is proposed for multi-sensor fusion and fault sensor identification. A new metric defined as the product of two evidences' conflict mass and distance is introduced to measure two evidences' conflict. The evidences are firstly modified according to the reliable coefficients calculated from the conflict, and fused by use of the D-S rule. The new conflict metric integrates the influence of both goal congruence and overall discrepancy. When the evidences have strong uncertainty and unreliability, it is more appropriate than that only using conflict mass or distance. The method is applied in state monitoring of a micro-satellite's power subsystem, approving that it could identify the system state and fault sensor more accurately than other methods. [ABSTRACT FROM AUTHOR]