It is difficult to compute far-field waves in a relative large area by using one wave generation model when a large calculation domain is needed because of large dimensions of the waterway and long distance of the req...It is difficult to compute far-field waves in a relative large area by using one wave generation model when a large calculation domain is needed because of large dimensions of the waterway and long distance of the required computing points. Variation of waterway bathymetry and nonlinearity in the far field cannot be included in a ship fixed process either. A coupled method combining a wave generation model and wave propagation model is then used in this paper to simulate the wash waves generated by the passing ship. A NURBS-based higher order panel method is adopted as the stationary wave generation model; a wave spectrum method and Boussinesq-type equation wave model are used as the wave propagation model for the constant water depth condition and variable water depth condition, respectively. The waves calculated by the NURBS-based higher order panel method in the near field are used as the input for the wave spectrum method and the Boussinesq-type equation wave model to obtain the far-field waves. With this approach it is possible to simulate the ship wash waves including the effects of water depth and waterway bathymetry. Parts of the calculated results are validated experimentally, and the agreement is demonstrated. The effects of ship wash waves on the moored ship are discussed by using a diffraction theory method. The results indicate that the prediction of the ship induced waves by coupling models is feasible.展开更多
Washing using ceramic micro-filtration membranes was studied in the preparation of nano-sized TiO2 and A1203 powder precursors obtained by wet chemical methods. The key parameters for the washing process, such as oper...Washing using ceramic micro-filtration membranes was studied in the preparation of nano-sized TiO2 and A1203 powder precursors obtained by wet chemical methods. The key parameters for the washing process, such as operation pressure, cross-flow velocity, and slurry concentration, were examined and optimized. The shape and size of particles influenced the structure of the filter cake, leading to different permeation flux for different systems. The results demonstrated that washing using ceramic membranes is superior to the traditional plate-and-frame filtration and could be considered an advanced technique for ultra-fine powder preparation by wet-chemical method.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.50879066 and 51409201)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.200804970009)
文摘It is difficult to compute far-field waves in a relative large area by using one wave generation model when a large calculation domain is needed because of large dimensions of the waterway and long distance of the required computing points. Variation of waterway bathymetry and nonlinearity in the far field cannot be included in a ship fixed process either. A coupled method combining a wave generation model and wave propagation model is then used in this paper to simulate the wash waves generated by the passing ship. A NURBS-based higher order panel method is adopted as the stationary wave generation model; a wave spectrum method and Boussinesq-type equation wave model are used as the wave propagation model for the constant water depth condition and variable water depth condition, respectively. The waves calculated by the NURBS-based higher order panel method in the near field are used as the input for the wave spectrum method and the Boussinesq-type equation wave model to obtain the far-field waves. With this approach it is possible to simulate the ship wash waves including the effects of water depth and waterway bathymetry. Parts of the calculated results are validated experimentally, and the agreement is demonstrated. The effects of ship wash waves on the moored ship are discussed by using a diffraction theory method. The results indicate that the prediction of the ship induced waves by coupling models is feasible.
基金financially supported by the Ministry of Science and Technology of China (Contract No. 2003CB615700)the Foundation of Science and Technology of the Educational Office of Anhui province, China (Contract No. 2005kj138)
文摘Washing using ceramic micro-filtration membranes was studied in the preparation of nano-sized TiO2 and A1203 powder precursors obtained by wet chemical methods. The key parameters for the washing process, such as operation pressure, cross-flow velocity, and slurry concentration, were examined and optimized. The shape and size of particles influenced the structure of the filter cake, leading to different permeation flux for different systems. The results demonstrated that washing using ceramic membranes is superior to the traditional plate-and-frame filtration and could be considered an advanced technique for ultra-fine powder preparation by wet-chemical method.
