Flexible risers and steel catenary risers often provide unique riser solutions for today’s deepwater field development. Accurate analysis of these slender structures, in which there are high-speed HP/HT internal flow...Flexible risers and steel catenary risers often provide unique riser solutions for today’s deepwater field development. Accurate analysis of these slender structures, in which there are high-speed HP/HT internal flows, is critical to ensure personnel and asset safety. In this study, a special global coordinate-based FEM rod model was adopted to identify and quantify the effects of internal flow and hydrostatic pressure on both flexible and deepwater steel catenary risers, with emphasis on the latter. By incorporating internal flow induced forces into the model, it was found that the internal flow contributes a new term to the effective tension expression. For flexible risers in shallow water, internal flow and hydrostatic pressure made virtually no change to effective tension by merely altering the riser wall tension. In deep water the internal pressure wielded a dominant role in governing the riser effective tension and furthering the static configuration, while the effect of inflow velocity was negligible. With respect to the riser seabed interaction, both the seabed support and friction effect were considered, with the former modeled by a nonlinear quadratic spring, allowing for a consistent derivation of the tangent stiffness matrix. The presented application examples show that the nonlinear quadratic spring is, when using the catenary solution as an initial static profile, an efficient way to model the quasi-Winkler-type elastic seabed foundation in this finite element scheme.展开更多
Industrial cluster has become an important part of regional economy,which status of global industry value chain is critical in the future, Innovation-based Cluster is the industrial cluster theory research at home and...Industrial cluster has become an important part of regional economy,which status of global industry value chain is critical in the future, Innovation-based Cluster is the industrial cluster theory research at home and abroad made to deepen the difference between the lower part of the Industrial cluster. Promoting innovative industrial cluster formation not only is one of the important means and carrier to cultivate strategic emerging industries, but also an important booster construction of national innovation system. According to the connotation,evolution process and characteristics of the Innovation-based Cluster, This paper from the perspective of three to analysis Innovation-based Clusters＇ innovative influence factors to find reasonable explanation to the creative industry cluster formation and more in-depth research.展开更多
Abstract The authors prove an almost sure central limit theorem for partial sums based on an irreducible and positive recurrent Markov chain using logarithmic means, which realizes the extension of the almost sure cen...Abstract The authors prove an almost sure central limit theorem for partial sums based on an irreducible and positive recurrent Markov chain using logarithmic means, which realizes the extension of the almost sure central limit theorem for partial sums from an i.i.d, sequence of random variables to a Markov chain.展开更多
We obtain an equation among invariants obtained from the Alexander module of an amphicheiral link. For special cases, it deduces necessary conditions on the Alexander polynomial. By using the present results and some ...We obtain an equation among invariants obtained from the Alexander module of an amphicheiral link. For special cases, it deduces necessary conditions on the Alexander polynomial. By using the present results and some known results, we show that the Alexander polynomial of an algebraically split component- preservingly （±）-amphicheiral link with even components is zero, and we determine prime amphieheiral links with at least 2 components and up to 9 crossings.展开更多
基金Supported by the National High-tech Research and Development Program of China (863 Program) under Grant No. 2010AA09Z303the Key Project of National Natural Science Foundation of China (Grant No. 50739004)the National Natural Science Foundation of China (Grant No. 11002135)
文摘Flexible risers and steel catenary risers often provide unique riser solutions for today’s deepwater field development. Accurate analysis of these slender structures, in which there are high-speed HP/HT internal flows, is critical to ensure personnel and asset safety. In this study, a special global coordinate-based FEM rod model was adopted to identify and quantify the effects of internal flow and hydrostatic pressure on both flexible and deepwater steel catenary risers, with emphasis on the latter. By incorporating internal flow induced forces into the model, it was found that the internal flow contributes a new term to the effective tension expression. For flexible risers in shallow water, internal flow and hydrostatic pressure made virtually no change to effective tension by merely altering the riser wall tension. In deep water the internal pressure wielded a dominant role in governing the riser effective tension and furthering the static configuration, while the effect of inflow velocity was negligible. With respect to the riser seabed interaction, both the seabed support and friction effect were considered, with the former modeled by a nonlinear quadratic spring, allowing for a consistent derivation of the tangent stiffness matrix. The presented application examples show that the nonlinear quadratic spring is, when using the catenary solution as an initial static profile, an efficient way to model the quasi-Winkler-type elastic seabed foundation in this finite element scheme.
文摘Industrial cluster has become an important part of regional economy,which status of global industry value chain is critical in the future, Innovation-based Cluster is the industrial cluster theory research at home and abroad made to deepen the difference between the lower part of the Industrial cluster. Promoting innovative industrial cluster formation not only is one of the important means and carrier to cultivate strategic emerging industries, but also an important booster construction of national innovation system. According to the connotation,evolution process and characteristics of the Innovation-based Cluster, This paper from the perspective of three to analysis Innovation-based Clusters＇ innovative influence factors to find reasonable explanation to the creative industry cluster formation and more in-depth research.
基金supported by the National Natural Science Foundation of China (No. 11171275)the Program for Excellent Talents in Chongqing Higher Education Institutions (No. 120060-20600204)Liaocheng University Foundation (No. X09005)
文摘Abstract The authors prove an almost sure central limit theorem for partial sums based on an irreducible and positive recurrent Markov chain using logarithmic means, which realizes the extension of the almost sure central limit theorem for partial sums from an i.i.d, sequence of random variables to a Markov chain.
基金supported by National Natural Science Foundation of China (Grant No. 10801021/a010402)
文摘We obtain an equation among invariants obtained from the Alexander module of an amphicheiral link. For special cases, it deduces necessary conditions on the Alexander polynomial. By using the present results and some known results, we show that the Alexander polynomial of an algebraically split component- preservingly （±）-amphicheiral link with even components is zero, and we determine prime amphieheiral links with at least 2 components and up to 9 crossings.
