Sound propagation in a deep ocean two-axis underwater channel is often complex and difficult to simulate between surface channel and sound fixing and ranging (SOFAR) channel. The beam-displacement ray-mode (BDRM) theo...Sound propagation in a deep ocean two-axis underwater channel is often complex and difficult to simulate between surface channel and sound fixing and ranging (SOFAR) channel. The beam-displacement ray-mode (BDRM) theory is a normal mode method for propagation modeling in horizontally stratified shallow water. An improved method for computing the upper boundary reflection coefficient in the BDRM is proposed and applied to calculate the acoustic fields of a two-axis underwater channel. Transmission losses in the two-axis underwater channel are calculated in the new BDRM. The corresponding results are in good agreement with those from the Kraken code, and furthermore the computed speed of the new BDRM excels the other methods.展开更多
Owing to the multipath effect, the source localization in shallow water has been an area of active interest. However, most methods for source localization in shallow water are sensitive to the assumed model of the und...Owing to the multipath effect, the source localization in shallow water has been an area of active interest. However, most methods for source localization in shallow water are sensitive to the assumed model of the underwater environment and have poor robustness against the underwater channel uncertainty, which limit their further application in practical engineering. In this paper, a new method of source localization in shallow water, based on vector optimization concept, is described, which is highly robust against environmental factors affecting the localization, such as the channel depth, the bottom reflection coefficients, and so on. Through constructing the uncertainty set of the source vector errors and extracting the multi-path sound rays from the sea surface and bottom, the proposed method can accurately localize one or more sources in shallow water dominated by multipath propagation. It turns out that the natural formulation of our approach involves minimization of two quadratic functions subject to infinitely many nonconvex quadratic constraints. It shows that this problem (originally intractable) can be reformulated in a convex form as the so-called second-order cone program (SOCP) and solved efficiently by using the well-established interior point method, such as the software tool, SeDuMi. Computer simulations show better performance of the proposed method as compared with existing algorithms and establish a theoretical foundation for the practical engineering application.展开更多
On February 5,2013,Qujjiang Culture&Tourism Group opened the Polar World as the second phase of Qujiang Ocean Park.The Polar World,featuring the theme of"snow and ice",is composed of a series of faciliti...On February 5,2013,Qujjiang Culture&Tourism Group opened the Polar World as the second phase of Qujiang Ocean Park.The Polar World,featuring the theme of"snow and ice",is composed of a series of facilities,including"Joy Show Court"which is a large animal show venue capable of holding up to 3,000 audiences,experience展开更多
In virtue of reference Cartesian coordinates,geometrical relations of spatial curved structure are presented in orthogonal curvilinear coordinates.Dynamic equations for helical girder are derived by Hamilton principle...In virtue of reference Cartesian coordinates,geometrical relations of spatial curved structure are presented in orthogonal curvilinear coordinates.Dynamic equations for helical girder are derived by Hamilton principle.These equations indicate that four generalized displacements are coupled with each other.When spatial structure degener- ates into planar curvilinear structure,two generalized displacements in two perpendicular planes are coupled with each other.Dynamic equations for arbitrary curvilinear structure may be obtained by the method used in this paper.展开更多
基金This project was supported by National Defense Research Found (No. 9140A03050206JB1501)
文摘Sound propagation in a deep ocean two-axis underwater channel is often complex and difficult to simulate between surface channel and sound fixing and ranging (SOFAR) channel. The beam-displacement ray-mode (BDRM) theory is a normal mode method for propagation modeling in horizontally stratified shallow water. An improved method for computing the upper boundary reflection coefficient in the BDRM is proposed and applied to calculate the acoustic fields of a two-axis underwater channel. Transmission losses in the two-axis underwater channel are calculated in the new BDRM. The corresponding results are in good agreement with those from the Kraken code, and furthermore the computed speed of the new BDRM excels the other methods.
基金This Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No.20122304120011)the Fundamental Research Funds for the Central Universities of Ministry of Education of China (Grant No.HEUCFR1119)
文摘Owing to the multipath effect, the source localization in shallow water has been an area of active interest. However, most methods for source localization in shallow water are sensitive to the assumed model of the underwater environment and have poor robustness against the underwater channel uncertainty, which limit their further application in practical engineering. In this paper, a new method of source localization in shallow water, based on vector optimization concept, is described, which is highly robust against environmental factors affecting the localization, such as the channel depth, the bottom reflection coefficients, and so on. Through constructing the uncertainty set of the source vector errors and extracting the multi-path sound rays from the sea surface and bottom, the proposed method can accurately localize one or more sources in shallow water dominated by multipath propagation. It turns out that the natural formulation of our approach involves minimization of two quadratic functions subject to infinitely many nonconvex quadratic constraints. It shows that this problem (originally intractable) can be reformulated in a convex form as the so-called second-order cone program (SOCP) and solved efficiently by using the well-established interior point method, such as the software tool, SeDuMi. Computer simulations show better performance of the proposed method as compared with existing algorithms and establish a theoretical foundation for the practical engineering application.
文摘On February 5,2013,Qujjiang Culture&Tourism Group opened the Polar World as the second phase of Qujiang Ocean Park.The Polar World,featuring the theme of"snow and ice",is composed of a series of facilities,including"Joy Show Court"which is a large animal show venue capable of holding up to 3,000 audiences,experience
基金the National Natural Science Foundation of China(No.10532070)
文摘In virtue of reference Cartesian coordinates,geometrical relations of spatial curved structure are presented in orthogonal curvilinear coordinates.Dynamic equations for helical girder are derived by Hamilton principle.These equations indicate that four generalized displacements are coupled with each other.When spatial structure degener- ates into planar curvilinear structure,two generalized displacements in two perpendicular planes are coupled with each other.Dynamic equations for arbitrary curvilinear structure may be obtained by the method used in this paper.
