Large vertical steel tanks for fluid storage are usually constructed on soft foundations, so it is not surprising that the tank wall will settle unevenly with the settlement of the foundation, thus inducing deformatio...Large vertical steel tanks for fluid storage are usually constructed on soft foundations, so it is not surprising that the tank wall will settle unevenly with the settlement of the foundation, thus inducing deformations and stresses in the tank. This work investigates the linear static behavior of floating-roof tanks under harmonic settlement through finite element (FE) analyses. The influences of the radius-to-thickness ratio, the height-to-radius ratio and the wind girder stiffness on the structural behavior are first analyzed. Comparisons between the circumferential stresses in the wind girder and the vertical stresses in the tank bottom are then made. The displacement and the stress along the tank height are also discussed, and the concept of tank division along its height is presented. Finally, a design approximation for the radial displacement at the tank top is developed based on FE results, and a settlement criterion based on the top radial displacement is proposed which can be used in practical design.展开更多
In this paper, a model of photonic crystal temperature sensor based on crystal microcavity in a straight photonic crystal waveguide is proposed. The transmission characteristics of light in the sensor under different ...In this paper, a model of photonic crystal temperature sensor based on crystal microcavity in a straight photonic crystal waveguide is proposed. The transmission characteristics of light in the sensor under different temperatures are simulated by using finite-difference time-domain (FDTD) method. The thermal expansion and thermal-optic effects of silicon are taken into account. The results show that the resonant wavelength of microcavity increases linearly as the temperature rising. The wavelength shift along with temperature is 6.6 pm /℃.展开更多
In this paper, we construct a continuous positive periodic function p(t) such that the corresponding superlinear Duffing equation x′′+ a(x)^(x2n+1)+p(t)x^(2m+1)= 0, n + 2≤2 m+1<2n+1 possesses a solution which es...In this paper, we construct a continuous positive periodic function p(t) such that the corresponding superlinear Duffing equation x′′+ a(x)^(x2n+1)+p(t)x^(2m+1)= 0, n + 2≤2 m+1<2n+1 possesses a solution which escapes to infinity in some finite time, and also has infinitely many subharmonic and quasi-periodic solutions, where the coefficient a(x) is an arbitrary positive smooth periodic function defined in the whole real axis.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 50208017) and the Scientific Research Foundation forReturned Overseas Chinese Scholars, Ministry of Education (No.J20040157), China
文摘Large vertical steel tanks for fluid storage are usually constructed on soft foundations, so it is not surprising that the tank wall will settle unevenly with the settlement of the foundation, thus inducing deformations and stresses in the tank. This work investigates the linear static behavior of floating-roof tanks under harmonic settlement through finite element (FE) analyses. The influences of the radius-to-thickness ratio, the height-to-radius ratio and the wind girder stiffness on the structural behavior are first analyzed. Comparisons between the circumferential stresses in the wind girder and the vertical stresses in the tank bottom are then made. The displacement and the stress along the tank height are also discussed, and the concept of tank division along its height is presented. Finally, a design approximation for the radial displacement at the tank top is developed based on FE results, and a settlement criterion based on the top radial displacement is proposed which can be used in practical design.
基金surpported by the National 863 Project of China (No.2007AA03Z413)the National Nature Science Foundation of China (No.60727004)the Project of Education Office of Shanxi Province of China (No.09JS041)
文摘In this paper, a model of photonic crystal temperature sensor based on crystal microcavity in a straight photonic crystal waveguide is proposed. The transmission characteristics of light in the sensor under different temperatures are simulated by using finite-difference time-domain (FDTD) method. The thermal expansion and thermal-optic effects of silicon are taken into account. The results show that the resonant wavelength of microcavity increases linearly as the temperature rising. The wavelength shift along with temperature is 6.6 pm /℃.
基金supported by National Natural Science Foundation of China (Grant No.11571041)the Fundamental Research Funds for the Central Universities
文摘In this paper, we construct a continuous positive periodic function p(t) such that the corresponding superlinear Duffing equation x′′+ a(x)^(x2n+1)+p(t)x^(2m+1)= 0, n + 2≤2 m+1<2n+1 possesses a solution which escapes to infinity in some finite time, and also has infinitely many subharmonic and quasi-periodic solutions, where the coefficient a(x) is an arbitrary positive smooth periodic function defined in the whole real axis.
