The singularities and oscillatory performance of translating-pulsating source Green＇s function in Bessho form were analyzed. Relative numerical integration methods such as Gaussian quadrature rule, variable substitut...The singularities and oscillatory performance of translating-pulsating source Green＇s function in Bessho form were analyzed. Relative numerical integration methods such as Gaussian quadrature rule, variable substitution method （VSM）, and steepest descent integration method （SDIM） were used to evaluate this type of Green＇s function. For SDIM, the complex domain was restricted only on the 0-plane. Meanwhile, the integral along the real axis was computed by use of the VSM to avoid the complication of a numerical search of the steepest descent line. Furthermore, the steepest descent line was represented by the B-spline function. Based on this representation, a new self-compatible integration method corresponding to parametric t was established. The numerical method was validated through comparison with other existing results, and was shown to be efficient and reliable in the calculation of the velocity potentials for the 3D seakeeping and hydrodynamic performance of floating struc- tures moving in waves.展开更多
Bismuth substituted cobalt nano ferrites with the chemical composition Co Bi<sub>x</sub> Fe<sub>2-x</sub> O<sub>4</sub> (x = 0.00, 0.05, 0.10, 0.15, 0.20 & 0.25) were prepared b...Bismuth substituted cobalt nano ferrites with the chemical composition Co Bi<sub>x</sub> Fe<sub>2-x</sub> O<sub>4</sub> (x = 0.00, 0.05, 0.10, 0.15, 0.20 & 0.25) were prepared by sol-gel combustion method. The phase identification of prepared samples is characterised by X-ray powder diffraction (XRD) method, which confirms the formation of a single phase fcc spinal structure. The mean crystallite sizes of all prepared samples were obtained within the range of 21 (±5) nm. Transmission Electron Microscopy (TEM) images also confirmed the crystallite size of all the synthesised samples was in nano range. With the effect of Bi<sup>3+</sup> ion substitution on spinal cobalt ferrite, the magnetic properties were investigated by using Vibration Sample Magnetometer (VSM). The obtained hysteresis (M-H) curves of all the samples were analysed under the applied magnetic field of range ± 10 K Oe at 300 K. The magnetic properties such as saturation magnetisation (M<sub>s</sub>), remnant magnetization (M<sub>r</sub>) and coercivity (H<sub>c</sub>) values are tabulated, which show a decrease in trend as the bismuth ion concentration increases. This is due to the addition of Bi<sup>3+</sup> ion in the place of Fe<sup>3+</sup> ion (octahedral site) and hence the Bi<sup>3+</sup>-Fe<sup>3+</sup> ion interaction predominates as compared with the Fe<sup>2+</sup>-Fe<sup>3+</sup> ion interaction. The data obtained from magnetic studies, the variation among the magnetic properties have been investigated for all the prepared samples.展开更多
基金Project supported by the National Natural Science Foundation of China （No. 50879090）, and the Key Research Program of Hydrody- namics of China （No. 9140A 14030712JB 11044）
文摘The singularities and oscillatory performance of translating-pulsating source Green＇s function in Bessho form were analyzed. Relative numerical integration methods such as Gaussian quadrature rule, variable substitution method （VSM）, and steepest descent integration method （SDIM） were used to evaluate this type of Green＇s function. For SDIM, the complex domain was restricted only on the 0-plane. Meanwhile, the integral along the real axis was computed by use of the VSM to avoid the complication of a numerical search of the steepest descent line. Furthermore, the steepest descent line was represented by the B-spline function. Based on this representation, a new self-compatible integration method corresponding to parametric t was established. The numerical method was validated through comparison with other existing results, and was shown to be efficient and reliable in the calculation of the velocity potentials for the 3D seakeeping and hydrodynamic performance of floating struc- tures moving in waves.
文摘Bismuth substituted cobalt nano ferrites with the chemical composition Co Bi<sub>x</sub> Fe<sub>2-x</sub> O<sub>4</sub> (x = 0.00, 0.05, 0.10, 0.15, 0.20 & 0.25) were prepared by sol-gel combustion method. The phase identification of prepared samples is characterised by X-ray powder diffraction (XRD) method, which confirms the formation of a single phase fcc spinal structure. The mean crystallite sizes of all prepared samples were obtained within the range of 21 (±5) nm. Transmission Electron Microscopy (TEM) images also confirmed the crystallite size of all the synthesised samples was in nano range. With the effect of Bi<sup>3+</sup> ion substitution on spinal cobalt ferrite, the magnetic properties were investigated by using Vibration Sample Magnetometer (VSM). The obtained hysteresis (M-H) curves of all the samples were analysed under the applied magnetic field of range ± 10 K Oe at 300 K. The magnetic properties such as saturation magnetisation (M<sub>s</sub>), remnant magnetization (M<sub>r</sub>) and coercivity (H<sub>c</sub>) values are tabulated, which show a decrease in trend as the bismuth ion concentration increases. This is due to the addition of Bi<sup>3+</sup> ion in the place of Fe<sup>3+</sup> ion (octahedral site) and hence the Bi<sup>3+</sup>-Fe<sup>3+</sup> ion interaction predominates as compared with the Fe<sup>2+</sup>-Fe<sup>3+</sup> ion interaction. The data obtained from magnetic studies, the variation among the magnetic properties have been investigated for all the prepared samples.
