Demand for high-speed marine vehicles (HSMVs) is high among both commercial and naval users. It is the duty of the marine vessel's designer to provide a hull and propulsion system that diminishes drag, improves pr...Demand for high-speed marine vehicles (HSMVs) is high among both commercial and naval users. It is the duty of the marine vessel's designer to provide a hull and propulsion system that diminishes drag, improves propulsive efficiency, increases safety and improves maneuverability. From the propulsor side, surface piercing propellers (SPPs) should improve performance. Unlike immersed propellers, behavior of the SPP is affected by depth of immersion, Weber number and shaft inclination angle. This paper uses a practical numerical method to predict the hydrodynamic characteristics of an SPP. The critical advance velocity ratio is derived using the Weber number and pitch ratio in the transition mode, then the potential based boundary element method (BEM) is used on the engaged surfaces. Two models of three and six-bladed SPPs (SPP-1 and SPP-2) were selected and some results are shown.展开更多
The underground water quality model with non-linear inversion problem is ill-posed, and boils down to solving the minimum of nonlinear function. Genetic algorithms are adopted in a number of individuals of groups by i...The underground water quality model with non-linear inversion problem is ill-posed, and boils down to solving the minimum of nonlinear function. Genetic algorithms are adopted in a number of individuals of groups by iterative search to find the optimal solution of the problem, the encoding strings as its operational objective, and achieving the iterative calculations by the genetic operators. It is an effective method of inverse problems of groundwater, with incomparable advantages and practical significances.展开更多
Hausdorff distance between two compact sets, defined as the maximum distance from a point of one set to another set, has many application in computer science. It is a good measure for the similarity of two sets. This ...Hausdorff distance between two compact sets, defined as the maximum distance from a point of one set to another set, has many application in computer science. It is a good measure for the similarity of two sets. This paper proves that the shape distance between two compact sets in R^n defined by nfinimum Hausdorff distance under rigid motions is a distance. The authors introduce similarity comparison problems in protein science, and propose that this measure may have good application to comparison of protein structure as well. For calculation of this distance, the authors give one dimensional formulas for problems （2, n）, （3, 3）, and （3, 4）. These formulas can reduce time needed for solving these problems. The authors did some data, this formula can reduce time needed to one As n increases, it would save more time. numerical experiments for （2, n）. On these sets of fifteenth of the best algorithms known on average.展开更多
The HASM(high accuracy surface modeling) technique is based on the fundamental theory of surfaces,which has been proved to improve the interpolation accuracy in surface fitting.However,the integral iterative solution ...The HASM(high accuracy surface modeling) technique is based on the fundamental theory of surfaces,which has been proved to improve the interpolation accuracy in surface fitting.However,the integral iterative solution in previous studies resulted in high temporal complexity in computation and huge memory usage so that it became difficult to put the technique into application,especially for large-scale datasets.In the study,an innovative model(HASM-AD) is developed according to the sequential least squares on the basis of data adjustment theory.Sequential division is adopted in the technique,so that linear equations can be divided into groups to be processed in sequence with the temporal complexity reduced greatly in computation.The experiment indicates that the HASM-AD technique surpasses the traditional spatial interpolation methods in accuracy.Also,the cross-validation result proves the same conclusion for the spatial interpolation of soil PH property with the data sampled in Jiangxi province.Moreover,it is demonstrated in the study that the HASM-AD technique significantly reduces the computational complexity and lessens memory usage in computation.展开更多
文摘Demand for high-speed marine vehicles (HSMVs) is high among both commercial and naval users. It is the duty of the marine vessel's designer to provide a hull and propulsion system that diminishes drag, improves propulsive efficiency, increases safety and improves maneuverability. From the propulsor side, surface piercing propellers (SPPs) should improve performance. Unlike immersed propellers, behavior of the SPP is affected by depth of immersion, Weber number and shaft inclination angle. This paper uses a practical numerical method to predict the hydrodynamic characteristics of an SPP. The critical advance velocity ratio is derived using the Weber number and pitch ratio in the transition mode, then the potential based boundary element method (BEM) is used on the engaged surfaces. Two models of three and six-bladed SPPs (SPP-1 and SPP-2) were selected and some results are shown.
文摘The underground water quality model with non-linear inversion problem is ill-posed, and boils down to solving the minimum of nonlinear function. Genetic algorithms are adopted in a number of individuals of groups by iterative search to find the optimal solution of the problem, the encoding strings as its operational objective, and achieving the iterative calculations by the genetic operators. It is an effective method of inverse problems of groundwater, with incomparable advantages and practical significances.
基金supported by the National Natural Science Foundation of China under Grant No. 10771206973 Project (2004CB318000) of China
文摘Hausdorff distance between two compact sets, defined as the maximum distance from a point of one set to another set, has many application in computer science. It is a good measure for the similarity of two sets. This paper proves that the shape distance between two compact sets in R^n defined by nfinimum Hausdorff distance under rigid motions is a distance. The authors introduce similarity comparison problems in protein science, and propose that this measure may have good application to comparison of protein structure as well. For calculation of this distance, the authors give one dimensional formulas for problems （2, n）, （3, 3）, and （3, 4）. These formulas can reduce time needed for solving these problems. The authors did some data, this formula can reduce time needed to one As n increases, it would save more time. numerical experiments for （2, n）. On these sets of fifteenth of the best algorithms known on average.
基金Supported by the National Science Fund for Distinguished Young Scholars (No. 40825003)the Major Directivity Projects of Chinese Academy of Science (No. kzcx2-yw-429)the National High-tech R&D Program of China (No. 2006AA12Z219)
文摘The HASM(high accuracy surface modeling) technique is based on the fundamental theory of surfaces,which has been proved to improve the interpolation accuracy in surface fitting.However,the integral iterative solution in previous studies resulted in high temporal complexity in computation and huge memory usage so that it became difficult to put the technique into application,especially for large-scale datasets.In the study,an innovative model(HASM-AD) is developed according to the sequential least squares on the basis of data adjustment theory.Sequential division is adopted in the technique,so that linear equations can be divided into groups to be processed in sequence with the temporal complexity reduced greatly in computation.The experiment indicates that the HASM-AD technique surpasses the traditional spatial interpolation methods in accuracy.Also,the cross-validation result proves the same conclusion for the spatial interpolation of soil PH property with the data sampled in Jiangxi province.Moreover,it is demonstrated in the study that the HASM-AD technique significantly reduces the computational complexity and lessens memory usage in computation.
