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Semi-analytical solution of optimization on moon-pool shaped WEC

Zhang W. C., Liu H. X., Zhang X. W., Zhang L.

Polish Maritime Research

2016

S 1

25--31

In order to effectively extract and maximize the energy from ocean waves, a new kind of oscillating-body WEC (wave energy converter) with moon pool has been put forward. The main emphasis in this paper is placed on inserting the damping into the equation of heaving motion applied for a complex wave energy converter and expressions for velocity potential added mass, damping coefficients associated with exciting forces were derived by using eigenfunction expansion matching method. By using surface-wave hydrodynamics, the exact theoretical conditions were solved to allow the maximum energy to be absorbed from regular waves. To optimize the ability of the wave energy conversion, oscillating system models under different radius-ratios are calculated and comparatively analyzed. Numerical calculations indicated that the capture width reaches the maximum in the vicinity of the natural frequency and the new kind of oscillating-body WEC has a positive ability of wave energy conversion.

Dielectric properties of Y-doped Ba1-xSrxTiO3 ceramics

Xu J., Liu H. X., He B., Hao H., Li Y. Q., Cao M. H., Yu Z. Y.

Optica Applicata

2010

Vol. 40, nr 1

255--264

Y-doped Ba1-xSrxTiO3 (Y-BST) ceramics (x = 0.1, 0.2, 0.4, 0.7) were prepared by solid-state reaction and sintered at 1250, 1300, 1350, and 1400 °C for 1 h. The effect of strontium solution and sintering temperature on the structure, microstructure and dielectric properties of Y-BST was investigated. SEM investigations revealed a grain size decreasing with the Sr content increase. The temperature dependence of permittivity showed decrease in phase transition temperature with higher Sr content. Enhancing sintering temperature is effective to increase the grain size and improve the microstructure porosity. The XRD patterns of all Y-doped Ba0.3Sr0.7TiO3ceramics indicated that the crystal cell parameters increase when temperature increased. However, the (002) and (200) peaks of Y-doped Ba0.3Sr0.7TiO3 split when sintering temperature was increased to 1400 °C, which makes the structure of the specimen transit to tetragonal (a = 3.9857 A and c = 4.018 A) from cubic. It may be attributed to the fact that Y3+ ion can occupy both A site and B site of Ba0.3Sr0.7TiO3 sintered at 1400 °C, which leads to the large different internal stress in individual grains, and then induces the structure change. The temperature coefficient of capacitance (TCC) value of the Y-doped Ba0.3Sr0.7TiO3 sintered at 1400 °C changed little within š6% over a temperature range from 10 to130 °C.