3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be effi...3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be efficient and stable. However, it has low calculation accuracy near the source, which thus gives it low overall accuracy. This paper proposes a joint traveltime calculation method to solve this problem. The method firstly employs the wavefront construction method （WFC）, which has a higher calculation accuracy than FMM in calculating traveltime in the small area near the source, and secondly adopts FMM to calculate traveltime for the remaining grid nodes. Due to the increase in calculation precision of grid nodes near the source, this new algorithm is shown to have good calculation precision while maintaining the high calculation efficiency of FMM, which is employed in most of the computational area. Results are verified using various numerical models.展开更多
The cable-strut structural system is statically and kinematically indeterminate. The initial pre-stress is a key factor for determining the shape and load carrying capacity. A new numerical algorithm is presented here...The cable-strut structural system is statically and kinematically indeterminate. The initial pre-stress is a key factor for determining the shape and load carrying capacity. A new numerical algorithm is presented herein for the initial pre-stress finding procedure of complete cable-strut assembly. This method is based on the linear adjustment theory and does not take into account the material behavior. By using this method,the initial pre-stress of the multi self-stress modes can be found easily and the cal-culation process is simplified and efficient also. Finally,the initial pre-stress and structural performances of a particular Levy cable dome are analyzed comprehensively. The algorithm has proven to be efficient and correct,and the numerical results are valuable for practical design of Levy cable dome.展开更多
This paper analyzes compositional strategies of Russian avant-garde architecture from the 1920s and 1930s through the study of the work of Ivan Leonidov （1902-1959）, one of the leading and most prolific architects o...This paper analyzes compositional strategies of Russian avant-garde architecture from the 1920s and 1930s through the study of the work of Ivan Leonidov （1902-1959）, one of the leading and most prolific architects of this movement. In this study, Leonidov＇s work is located within its predominant architectural context, and his work is interpreted not only as a reaction against the domineering principles of classicism, but as an evolution and selective continuation of key concepts directly translated from architectural academism. The issues of the use of pure forms--a radical stance at odds with the commonly accepted morphologies of that era--associated with the principles of displaced symmetry, or disorder, are closely looked at and evaluated against both their architectural and political values within the context of post-revolutionary Russia. It is argued that the characteristic of weightlessness in his large-scale planning proposals is revelatory of a particular desire to invade space with political presence, thus demanding to reconsider the relation between space and architectural objects. Parallels are also drawn from French Revolutionary architecture, and from the work of Claude-Nicolas Ledoux in particular, whose search for purity and autonomy in architectural morphology preceded that of Soviet architecture. As Leonidov＇s legacy mainly consists of drawings of buildings that never got built, his influence can often be felt in the work of other architects which until today have drawn formal elements and compositional strategies from his relatively vast volume of un-built work.展开更多
基金supported by NSFC(Nos.41274120,41404085,and 41504084)
文摘3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be efficient and stable. However, it has low calculation accuracy near the source, which thus gives it low overall accuracy. This paper proposes a joint traveltime calculation method to solve this problem. The method firstly employs the wavefront construction method （WFC）, which has a higher calculation accuracy than FMM in calculating traveltime in the small area near the source, and secondly adopts FMM to calculate traveltime for the remaining grid nodes. Due to the increase in calculation precision of grid nodes near the source, this new algorithm is shown to have good calculation precision while maintaining the high calculation efficiency of FMM, which is employed in most of the computational area. Results are verified using various numerical models.
基金Project (No.863-705-210) supported by the Hi-Tech Research and Development Program (863) of China
文摘The cable-strut structural system is statically and kinematically indeterminate. The initial pre-stress is a key factor for determining the shape and load carrying capacity. A new numerical algorithm is presented herein for the initial pre-stress finding procedure of complete cable-strut assembly. This method is based on the linear adjustment theory and does not take into account the material behavior. By using this method,the initial pre-stress of the multi self-stress modes can be found easily and the cal-culation process is simplified and efficient also. Finally,the initial pre-stress and structural performances of a particular Levy cable dome are analyzed comprehensively. The algorithm has proven to be efficient and correct,and the numerical results are valuable for practical design of Levy cable dome.
文摘This paper analyzes compositional strategies of Russian avant-garde architecture from the 1920s and 1930s through the study of the work of Ivan Leonidov （1902-1959）, one of the leading and most prolific architects of this movement. In this study, Leonidov＇s work is located within its predominant architectural context, and his work is interpreted not only as a reaction against the domineering principles of classicism, but as an evolution and selective continuation of key concepts directly translated from architectural academism. The issues of the use of pure forms--a radical stance at odds with the commonly accepted morphologies of that era--associated with the principles of displaced symmetry, or disorder, are closely looked at and evaluated against both their architectural and political values within the context of post-revolutionary Russia. It is argued that the characteristic of weightlessness in his large-scale planning proposals is revelatory of a particular desire to invade space with political presence, thus demanding to reconsider the relation between space and architectural objects. Parallels are also drawn from French Revolutionary architecture, and from the work of Claude-Nicolas Ledoux in particular, whose search for purity and autonomy in architectural morphology preceded that of Soviet architecture. As Leonidov＇s legacy mainly consists of drawings of buildings that never got built, his influence can often be felt in the work of other architects which until today have drawn formal elements and compositional strategies from his relatively vast volume of un-built work.
