Recent damages to the box-like structures caused by wave slamming have made it necessary to study the impact problems of this kind of structure. This paper showed findings from numerical simulations of the rigid/elast...Recent damages to the box-like structures caused by wave slamming have made it necessary to study the impact problems of this kind of structure. This paper showed findings from numerical simulations of the rigid/elastic structures, aiming to gain insights into the characteristics of the problem. The results of the rigid cases showed the significance of air compressibility during the impact process, while the slamming phenomena became quite different without the effect. In the elastic cases, the trapped air made the structure vibrate at frequencies much smaller than its eigenfrequencies. Besides, the structural deformation made it easy for the trapped air to escape outwards, which weakened the air cushioning effect, especially at high impact velocities. The above analysis gives the results when the structural symmetry axis was vertical to the water(vertical impacts). In addition, the results were given when the axis was oblique to the water(oblique impacts). Compared with the vertical cases, the impact phenomena and structural response showed asymmetry. This work used the computational fluid dynamics(CFD) method to describe fluid motion and the finite element method(FEM) for the deformable structure. A two-way coupling approach was used to deal with the fluid-structure interaction in the elastic cases.展开更多
An analytical model based on statistical energy analysis (SEA) is developed for the sound pressurelevels inside a box-like structure due to wide-band random excitation applied at a prescribed point on thestructure.So...An analytical model based on statistical energy analysis (SEA) is developed for the sound pressurelevels inside a box-like structure due to wide-band random excitation applied at a prescribed point on thestructure.Some conditions that the sound field inside cavity must adapts to SEA assumes are given. Thesound responses inside the box structure for four different input mobilities are predicted using the SEA modeland compared with expermental results On the basis of these results,possible ways of reducing the noise in-side the box structure are suggested.展开更多
An efficient technique is used to flatten the spectral response of an arrayed waveguide grating （AWG） multiplexer. By subtracting an increment from the core width of odd arrayed waveguides and by adding the same inc...An efficient technique is used to flatten the spectral response of an arrayed waveguide grating （AWG） multiplexer. By subtracting an increment from the core width of odd arrayed waveguides and by adding the same increment to that of even arrayed waveguides,a box-like spectral response can be obtained. A 17 × 17 polymer AWG multiplexer with box- like spectral response has been made using FPE polymer materials. Measured result for the AWG shows that the box-like spectral response has a 3dB bandwidth of 0. 476nm, the crosstalk is about or less than - 21dB for every output channel,and the insertion loss is 13-15dB.展开更多
基金financially supported by the National Key Research and Development Program of China (Grant No. 2019YFC1407700)。
文摘Recent damages to the box-like structures caused by wave slamming have made it necessary to study the impact problems of this kind of structure. This paper showed findings from numerical simulations of the rigid/elastic structures, aiming to gain insights into the characteristics of the problem. The results of the rigid cases showed the significance of air compressibility during the impact process, while the slamming phenomena became quite different without the effect. In the elastic cases, the trapped air made the structure vibrate at frequencies much smaller than its eigenfrequencies. Besides, the structural deformation made it easy for the trapped air to escape outwards, which weakened the air cushioning effect, especially at high impact velocities. The above analysis gives the results when the structural symmetry axis was vertical to the water(vertical impacts). In addition, the results were given when the axis was oblique to the water(oblique impacts). Compared with the vertical cases, the impact phenomena and structural response showed asymmetry. This work used the computational fluid dynamics(CFD) method to describe fluid motion and the finite element method(FEM) for the deformable structure. A two-way coupling approach was used to deal with the fluid-structure interaction in the elastic cases.
文摘An analytical model based on statistical energy analysis (SEA) is developed for the sound pressurelevels inside a box-like structure due to wide-band random excitation applied at a prescribed point on thestructure.Some conditions that the sound field inside cavity must adapts to SEA assumes are given. Thesound responses inside the box structure for four different input mobilities are predicted using the SEA modeland compared with expermental results On the basis of these results,possible ways of reducing the noise in-side the box structure are suggested.
基金supported by the National Natural Science Foundation of China(No.60576045)~~
文摘An efficient technique is used to flatten the spectral response of an arrayed waveguide grating （AWG） multiplexer. By subtracting an increment from the core width of odd arrayed waveguides and by adding the same increment to that of even arrayed waveguides,a box-like spectral response can be obtained. A 17 × 17 polymer AWG multiplexer with box- like spectral response has been made using FPE polymer materials. Measured result for the AWG shows that the box-like spectral response has a 3dB bandwidth of 0. 476nm, the crosstalk is about or less than - 21dB for every output channel,and the insertion loss is 13-15dB.
