A new research perspective is proposed to optimize the topology of truss structure by force cone method,which involves force cone drawing rules and growth rules.Through the comparison with the mature variable density ...A new research perspective is proposed to optimize the topology of truss structure by force cone method,which involves force cone drawing rules and growth rules.Through the comparison with the mature variable density topology optimization method,the effectiveness of force cone method is verified.This kind of new method is simple and easy to understand(no need to master complex structural optimization design theory).Besides,it is time-saving in finite element calculations,and can obtain an optimized truss layout easily.By drawing the force cone,its application on a large radio telescope’s back frame structure shows that,compared with the existing one in terms of structural stiffness,Root Mean Square(RMS)precision,and beam stress distribution,the optimized back frame using the force cone method has higher stiffness,better RMS,more uniform stress,and lighter weight.展开更多
Compared with scattering from a rough surface only, composite scattering from a target above a rough surface has become so practical that it is a subject of great interest. At present, this problem has been solved by ...Compared with scattering from a rough surface only, composite scattering from a target above a rough surface has become so practical that it is a subject of great interest. At present, this problem has been solved by some numerical methods which will produce an enormous calculation amount. In order to overcome this shortcoming, the reciprocity theorem （RT） and the method of equivalent edge currents （MEC） are used in this paper. Due to the advantage of RT, the difficulty in computing the secondary scattered fields is reduced. Simultaneously, MEC, a high-frequency method with edge diffraction considered, is used to calculate the scattered field from the cone-cylinder target with a high accuracy and efficiency. The backscattered field and the polarization currents of the rough sea surface are evaluated by the Kirchhoff approximation （KA） method and physical optics （PO） method, respectively. The effects of the backscattering radar cross section （RCS） and the Doppler spectrum on the size of the target and the windspeed of the sea surface for different incident angles are analysed in detail.展开更多
In this paper, we give some new results of common fixed point theorems and coincidence point case for some iterative method. By using of variation iteration method and an effective modification of He’s variation iter...In this paper, we give some new results of common fixed point theorems and coincidence point case for some iterative method. By using of variation iteration method and an effective modification of He’s variation iteration method discusses some integral and differential equations, we give out some new conclusion and more new examples.展开更多
In this paper, we study the existence result for degenerate elliptic equations with singular potential and critical cone sobolev exponents on singular manifolds. With the help of the variational method and the theory ...In this paper, we study the existence result for degenerate elliptic equations with singular potential and critical cone sobolev exponents on singular manifolds. With the help of the variational method and the theory of genus, we obtain several results under different conditions.展开更多
文摘A new research perspective is proposed to optimize the topology of truss structure by force cone method,which involves force cone drawing rules and growth rules.Through the comparison with the mature variable density topology optimization method,the effectiveness of force cone method is verified.This kind of new method is simple and easy to understand(no need to master complex structural optimization design theory).Besides,it is time-saving in finite element calculations,and can obtain an optimized truss layout easily.By drawing the force cone,its application on a large radio telescope’s back frame structure shows that,compared with the existing one in terms of structural stiffness,Root Mean Square(RMS)precision,and beam stress distribution,the optimized back frame using the force cone method has higher stiffness,better RMS,more uniform stress,and lighter weight.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60971067)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20070701010)
文摘Compared with scattering from a rough surface only, composite scattering from a target above a rough surface has become so practical that it is a subject of great interest. At present, this problem has been solved by some numerical methods which will produce an enormous calculation amount. In order to overcome this shortcoming, the reciprocity theorem （RT） and the method of equivalent edge currents （MEC） are used in this paper. Due to the advantage of RT, the difficulty in computing the secondary scattered fields is reduced. Simultaneously, MEC, a high-frequency method with edge diffraction considered, is used to calculate the scattered field from the cone-cylinder target with a high accuracy and efficiency. The backscattered field and the polarization currents of the rough sea surface are evaluated by the Kirchhoff approximation （KA） method and physical optics （PO） method, respectively. The effects of the backscattering radar cross section （RCS） and the Doppler spectrum on the size of the target and the windspeed of the sea surface for different incident angles are analysed in detail.
文摘In this paper, we give some new results of common fixed point theorems and coincidence point case for some iterative method. By using of variation iteration method and an effective modification of He’s variation iteration method discusses some integral and differential equations, we give out some new conclusion and more new examples.
文摘In this paper, we study the existence result for degenerate elliptic equations with singular potential and critical cone sobolev exponents on singular manifolds. With the help of the variational method and the theory of genus, we obtain several results under different conditions.
