In 1875,the HMS(皇家海军舰艇)Challenger stopped in the middle of the Pacific Ocean,southwest of the Mariana Islands,to conduct a routine depth sounding.As they'd done countless times before,the British scientists ...In 1875,the HMS(皇家海军舰艇)Challenger stopped in the middle of the Pacific Ocean,southwest of the Mariana Islands,to conduct a routine depth sounding.As they'd done countless times before,the British scientists and sailors on board lowered a weighted rope into the water.Unlike those other times,however,the rope kept falling,seemingly without an end.After nearly 8,230 meters,it finally hit the bottom—the first human attempt at what became known as the Mariana Trench.展开更多
A coupled-mode sound propagation model with complex effective depth is presented,in order to involve the effect of branch line integral for acoustic field in a range-dependent waveguide.The equations of motion and con...A coupled-mode sound propagation model with complex effective depth is presented,in order to involve the effect of branch line integral for acoustic field in a range-dependent waveguide.The equations of motion and continuity are used to obtain the coupled equations,which satisfy boundary conditions in the waveguide with varying topography and contain one coupling matrix.Meanwhile,the couplings between discrete and continuous spectrum are dealt with based on complex effective depth theory.Numerical simulations show that the accuracy of transmission loss is improved by the coupled mode model when eigenvalues of trapped modes are located near the branch point.The acoustic field in a non-horizontally stratified waveguide can be calculated efficiently and accurately by this model,and the energy corresponding to trapped modes,leaky modes and branch line integral can be considered adequately.展开更多
文摘In 1875,the HMS(皇家海军舰艇)Challenger stopped in the middle of the Pacific Ocean,southwest of the Mariana Islands,to conduct a routine depth sounding.As they'd done countless times before,the British scientists and sailors on board lowered a weighted rope into the water.Unlike those other times,however,the rope kept falling,seemingly without an end.After nearly 8,230 meters,it finally hit the bottom—the first human attempt at what became known as the Mariana Trench.
基金supported by the Science and Technology Foundation of State Key Laboratory,China(9140C200103120C2001)the National Nature Science Foundation of China(11234002)
文摘A coupled-mode sound propagation model with complex effective depth is presented,in order to involve the effect of branch line integral for acoustic field in a range-dependent waveguide.The equations of motion and continuity are used to obtain the coupled equations,which satisfy boundary conditions in the waveguide with varying topography and contain one coupling matrix.Meanwhile,the couplings between discrete and continuous spectrum are dealt with based on complex effective depth theory.Numerical simulations show that the accuracy of transmission loss is improved by the coupled mode model when eigenvalues of trapped modes are located near the branch point.The acoustic field in a non-horizontally stratified waveguide can be calculated efficiently and accurately by this model,and the energy corresponding to trapped modes,leaky modes and branch line integral can be considered adequately.
