Papers by Author: Hong Liu

Abstract: Due to the existence of the accumulation errors in inertial navigation system(INS) and traditional point-mass filter (PMF) algorithm has problems of navigation precision and reliability when it is used for underwater terrain matching navigation, an improved PMF algorithm is proposed. Because the PMF algorithm is sensitive to initial errors and degeneration phenomenon usually appears with the increasing of matching number, the improved algorithm adopts cubic spline interpolation method to deal with the posterior probability density to prevent degeneration phenomenon. Then the TERCOM algorithm is introduced for initial alignment to reduce the influence of the initial errors. Finally the improved algorithm is simulated. The simulation results show the algorithm has a good robustness and accuracy.

Abstract: (1-x)(Na0.5Bi0.5)TiO3-xBaTiO3 (abbreviated as NBBT100(1-x)/100x or NBBT100x) solid solution single crystals with x=0, 0.06, 0.08, 0.10, 0.20, 1.0 were grown using top-seeded solution growth (TSSG) method. Dielectric, piezoelectric and ferroelectric properties of NBBT crystals were investigated as a function of temperature, frequency, composition and crystal orientation. The temperature (Tm) corresponding to dielectric maximum and the depolarization temperature (Td) decrease with increasing x. The <001> oriented NBBT90/10 single crystal shows excellent piezoelectric performance with piezoelectric constant (d33) value about 275pC/N and exhibits relatively smaller coercive field (Ec) of 2.49 kV/mm and dielectric loss tanδ of 2.9 %, indicating a more adaptive engineered domain structure.