This paper presents a frequency domain approach for the calculation of the random response of fluid-conveying steel catenary risers under random wave force.The partial differential equations of motion of the steel cat...This paper presents a frequency domain approach for the calculation of the random response of fluid-conveying steel catenary risers under random wave force.The partial differential equations of motion of the steel catenary riser under a combination of internal flow and random wave excitation are established based on a series of earlier publications.The mass matrix,stiffness matrix,damping matrix and wave loading for steel catenary riser are derived in frequency domain by using Hamilton's principle.Analysis of free vibrations is then carried out to investigate the effect of flow velocity on natural frequency.By further introducing the pseudo-excitation method,the dynamic analysis of the steel catenary riser subject to wave excitation is performed in frequency domain to see how the flow velocity affects the bending moment response of the steel catenary riser.The parametric studies on the example steel catenary riser show that flow velocity may decrease the natural frequencies and increase the dynamic response of the steel catenary riser.Moreover,the dynamic stability of fluid-conveying steel catenary risers is investigated and the critical fluid velocity is identified.展开更多
In the procedure of neutron fluence measurement in the whole energy range (10-4 eV^18 MeV), in the irra- diation chamber of a UZrH reactor, the neutron energy spectra are unfolded using the method of minimizing direct...In the procedure of neutron fluence measurement in the whole energy range (10-4 eV^18 MeV), in the irra- diation chamber of a UZrH reactor, the neutron energy spectra are unfolded using the method of minimizing directed divergence and SAND-II, which are used broadly at home and abroad. These methods belong to the iterative methods. In this article, the procedure of the spectra unfolding using the two methods is described in detail. The neutron spec- trum distribution unfolded by the two methods agree well with each other. In the end, the major differences of the two iterative methods are compared with each other, and the main factors affecting the accuracy of the spectra unfolding with the iterative method are discussed.展开更多
基金supported by the National Natural Science Foundation of China(No.11372060)
文摘This paper presents a frequency domain approach for the calculation of the random response of fluid-conveying steel catenary risers under random wave force.The partial differential equations of motion of the steel catenary riser under a combination of internal flow and random wave excitation are established based on a series of earlier publications.The mass matrix,stiffness matrix,damping matrix and wave loading for steel catenary riser are derived in frequency domain by using Hamilton's principle.Analysis of free vibrations is then carried out to investigate the effect of flow velocity on natural frequency.By further introducing the pseudo-excitation method,the dynamic analysis of the steel catenary riser subject to wave excitation is performed in frequency domain to see how the flow velocity affects the bending moment response of the steel catenary riser.The parametric studies on the example steel catenary riser show that flow velocity may decrease the natural frequencies and increase the dynamic response of the steel catenary riser.Moreover,the dynamic stability of fluid-conveying steel catenary risers is investigated and the critical fluid velocity is identified.
文摘In the procedure of neutron fluence measurement in the whole energy range (10-4 eV^18 MeV), in the irra- diation chamber of a UZrH reactor, the neutron energy spectra are unfolded using the method of minimizing directed divergence and SAND-II, which are used broadly at home and abroad. These methods belong to the iterative methods. In this article, the procedure of the spectra unfolding using the two methods is described in detail. The neutron spec- trum distribution unfolded by the two methods agree well with each other. In the end, the major differences of the two iterative methods are compared with each other, and the main factors affecting the accuracy of the spectra unfolding with the iterative method are discussed.
