Radar cross section (RCS) reduction technologies are very important in survivability of the military naval vessels. Ship appearance shaping as an effective countermeasure of RCS reduction redirects the scattered energ...Radar cross section (RCS) reduction technologies are very important in survivability of the military naval vessels. Ship appearance shaping as an effective countermeasure of RCS reduction redirects the scattered energy from one angular region of interest in space to another region of little interest. To decrease the scattering electromagnetic signals from ship scientifically, optimization methods should be introduced in shaping design. Based on the assumption of the characteristic section design method, mathematical formulations for optimal shaping design were established. Because of the computation-intensive analysis and singularity in shaping optimization, the response surface method (RSM) combined genetic algorithm (GA) was proposed. The poly-nomial response surface method was adopted in model approximation. Then genetic algorithms were employed to solve the surrogate optimization problem. By comparison RCS of the conventional and the optimal design, the superiority and effectiveness of proposed design methodology were verified.展开更多
In this paper,combined with the relevant speed theory and characteristics of the law,the current highway speed transition design problems are studied and analyzed.In the process of specific analysis,mainly combined wi...In this paper,combined with the relevant speed theory and characteristics of the law,the current highway speed transition design problems are studied and analyzed.In the process of specific analysis,mainly combined with the characteristics of different types of highway speed changes and road section design requirements,this paper studies and analyzes the design methods of different types of highway speed transition section.And on this basis,according to the design principles and requirements of highway operation speed transition section,the paper summarizes the matters needing attention in the design of highway operation speed transition section,in order to provide certain reference value for relevant personnel.展开更多
Production characteristics of high speed rod are fast speed,complex section and internal microstructure evolution,which bring great problems to analyze and solve the quality disputes.Therefore,a serial process models ...Production characteristics of high speed rod are fast speed,complex section and internal microstructure evolution,which bring great problems to analyze and solve the quality disputes.Therefore,a serial process models have been developed based on the characteristics of high speed rod:due to rod stock to be square section,a two dimension model has been developed to predict the evolution of internal temperature and grain coarsening.As for the rod rolling process,an automatic section design system has been written, which can show section filling condition and process parameters such as temperature,pressure and recrystallization etc per pass.As for rod cooling stage,an integrated model which coupled phase transformation,temperature and final properties was developed and applied in real production with good results.展开更多
A lift distribution based section design method has been proposed. Through Newton-Raphson iterations, the section geometry is efficiently designed to meet the requirements for total lift and lift distribution. The eff...A lift distribution based section design method has been proposed. Through Newton-Raphson iterations, the section geometry is efficiently designed to meet the requirements for total lift and lift distribution. The effect of fluid viscosity on total lift is taken into account by coupling Reynolds-averaged Navier-Stokes(RANS)simulation with the potential-flow based design procedure. The present method avoids the difficulty of assigning velocity or pressure distributions on section surfaces. As the loading and thickness distributions are expressed in parametric forms, it is easy to ensure that the designed geometry is continuous and smooth. The effects of lift and thickness distributions on cavitation bucket are numerically investigated. A shift of lift loading towards the aft part of section tends to decrease the margin of back cavitation, while the width of cavitation bucket can be kept almost unchanged. To have a wider cavitation bucket, one can increase the leading edge radius, move properly the location of maximum thickness towards the leading edge, or decrease the curvature at the location of maximum thickness.展开更多
Situated in the east of the old town ofHefei, the Dadongmen-Xiaodongmen sec-tion covering an area of 27 ha. is 900m fromsouth to north and 300m across from east
基金the National Natural Science Founda-tion of China (No. 10672100)
文摘Radar cross section (RCS) reduction technologies are very important in survivability of the military naval vessels. Ship appearance shaping as an effective countermeasure of RCS reduction redirects the scattered energy from one angular region of interest in space to another region of little interest. To decrease the scattering electromagnetic signals from ship scientifically, optimization methods should be introduced in shaping design. Based on the assumption of the characteristic section design method, mathematical formulations for optimal shaping design were established. Because of the computation-intensive analysis and singularity in shaping optimization, the response surface method (RSM) combined genetic algorithm (GA) was proposed. The poly-nomial response surface method was adopted in model approximation. Then genetic algorithms were employed to solve the surrogate optimization problem. By comparison RCS of the conventional and the optimal design, the superiority and effectiveness of proposed design methodology were verified.
文摘In this paper,combined with the relevant speed theory and characteristics of the law,the current highway speed transition design problems are studied and analyzed.In the process of specific analysis,mainly combined with the characteristics of different types of highway speed changes and road section design requirements,this paper studies and analyzes the design methods of different types of highway speed transition section.And on this basis,according to the design principles and requirements of highway operation speed transition section,the paper summarizes the matters needing attention in the design of highway operation speed transition section,in order to provide certain reference value for relevant personnel.
文摘Production characteristics of high speed rod are fast speed,complex section and internal microstructure evolution,which bring great problems to analyze and solve the quality disputes.Therefore,a serial process models have been developed based on the characteristics of high speed rod:due to rod stock to be square section,a two dimension model has been developed to predict the evolution of internal temperature and grain coarsening.As for the rod rolling process,an automatic section design system has been written, which can show section filling condition and process parameters such as temperature,pressure and recrystallization etc per pass.As for rod cooling stage,an integrated model which coupled phase transformation,temperature and final properties was developed and applied in real production with good results.
文摘A lift distribution based section design method has been proposed. Through Newton-Raphson iterations, the section geometry is efficiently designed to meet the requirements for total lift and lift distribution. The effect of fluid viscosity on total lift is taken into account by coupling Reynolds-averaged Navier-Stokes(RANS)simulation with the potential-flow based design procedure. The present method avoids the difficulty of assigning velocity or pressure distributions on section surfaces. As the loading and thickness distributions are expressed in parametric forms, it is easy to ensure that the designed geometry is continuous and smooth. The effects of lift and thickness distributions on cavitation bucket are numerically investigated. A shift of lift loading towards the aft part of section tends to decrease the margin of back cavitation, while the width of cavitation bucket can be kept almost unchanged. To have a wider cavitation bucket, one can increase the leading edge radius, move properly the location of maximum thickness towards the leading edge, or decrease the curvature at the location of maximum thickness.
文摘Situated in the east of the old town ofHefei, the Dadongmen-Xiaodongmen sec-tion covering an area of 27 ha. is 900m fromsouth to north and 300m across from east
