This work aimed to demonstrate possibilities for both active and passive control of the vortex-induced vibration and fatigue life of steel catenary risers via an analysis of the self-organization and evolution of the ...This work aimed to demonstrate possibilities for both active and passive control of the vortex-induced vibration and fatigue life of steel catenary risers via an analysis of the self-organization and evolution of the structural vibration based on synergetic theory. An analysis of the complex interrelated and synergistic relationship between the order parameter and the fast variable was performed, and the master equation of the nodal displacements was established as the order parameter for the evolution of the riser's structural vibration. Passive control methods include modifying the structure's elastic modulus, the internal fluid velocity, the top tension and the structural damping ratio, while an active control involves adjusting the external flow rate. Optimized parameters were obtained by analyzing the non-steady state solution of the master equation. The results show that the fatigue life greatly increases as the riser's elastic modulus decreases. In contrast, the fatigue life decreases with an increase of the internal fluid velocity. With an increase of the top tension, the vibration amplitudes and the number of modes may decrease, resulting in fewer bending stress cycles and a longer fatigue life. Furthermore, the structural damping ratio should be as large as possible. Finally, an active and passive control of the riser structure's response to vortex-induced vibration and its fatigue life can be achieved by carefully modifying the parameters mentioned above. The results may provide a theoretical framework for engineering practice concerning the design and control of steel catenary riser structures which are affected by vortex-induced vibration.展开更多
The terms ＂soul,＂ ＂spirit,＂ ＂breath,＂ and ＂life＂ occur several times each in the Book of Job. A proper understanding of these terms in Scripture, especially ＂soul＂ and ＂spirit＂ is integral to understanding...The terms ＂soul,＂ ＂spirit,＂ ＂breath,＂ and ＂life＂ occur several times each in the Book of Job. A proper understanding of these terms in Scripture, especially ＂soul＂ and ＂spirit＂ is integral to understanding the state of the dead, among others. These terms are used in diverse contexts with interchangeable nuances in the Book of Job. A living （＂life＂） person （＂soul＂） consists of the body/flesh plus the life principle （＂spirit＂） of which ＂breath＂ is a concrete expression. In poetic contexts, the terminologies denote the physical （＂soul＂/＂life＂）, appetitive （＂soul＂/＂life＂）, psychical （＂spirit＂/＂breath＂）, and emotional （＂soul＂/＂spirit＂） characteristics of the human being. While ＂soul＂ and ＂life＂ tend towards physieality and therefore can be used synonymously for the whole person, ＂spirit＂ and ＂breath＂ tend towards non-physicality and express such phenomena as intellection and wind. A study of these terminologies in other poetic texts in the Hebrew Bible may evince similar semantic configurations as found in the Book of Job.展开更多
基金Financial support from the China Postdoctoral Science Foundation Fund (Grant No.2013M531563)the Qingdao Agricultural University High-Level Talents Research Fund (Grant No. 631424)is gratefully acknowledged
文摘This work aimed to demonstrate possibilities for both active and passive control of the vortex-induced vibration and fatigue life of steel catenary risers via an analysis of the self-organization and evolution of the structural vibration based on synergetic theory. An analysis of the complex interrelated and synergistic relationship between the order parameter and the fast variable was performed, and the master equation of the nodal displacements was established as the order parameter for the evolution of the riser's structural vibration. Passive control methods include modifying the structure's elastic modulus, the internal fluid velocity, the top tension and the structural damping ratio, while an active control involves adjusting the external flow rate. Optimized parameters were obtained by analyzing the non-steady state solution of the master equation. The results show that the fatigue life greatly increases as the riser's elastic modulus decreases. In contrast, the fatigue life decreases with an increase of the internal fluid velocity. With an increase of the top tension, the vibration amplitudes and the number of modes may decrease, resulting in fewer bending stress cycles and a longer fatigue life. Furthermore, the structural damping ratio should be as large as possible. Finally, an active and passive control of the riser structure's response to vortex-induced vibration and its fatigue life can be achieved by carefully modifying the parameters mentioned above. The results may provide a theoretical framework for engineering practice concerning the design and control of steel catenary riser structures which are affected by vortex-induced vibration.
文摘The terms ＂soul,＂ ＂spirit,＂ ＂breath,＂ and ＂life＂ occur several times each in the Book of Job. A proper understanding of these terms in Scripture, especially ＂soul＂ and ＂spirit＂ is integral to understanding the state of the dead, among others. These terms are used in diverse contexts with interchangeable nuances in the Book of Job. A living （＂life＂） person （＂soul＂） consists of the body/flesh plus the life principle （＂spirit＂） of which ＂breath＂ is a concrete expression. In poetic contexts, the terminologies denote the physical （＂soul＂/＂life＂）, appetitive （＂soul＂/＂life＂）, psychical （＂spirit＂/＂breath＂）, and emotional （＂soul＂/＂spirit＂） characteristics of the human being. While ＂soul＂ and ＂life＂ tend towards physieality and therefore can be used synonymously for the whole person, ＂spirit＂ and ＂breath＂ tend towards non-physicality and express such phenomena as intellection and wind. A study of these terminologies in other poetic texts in the Hebrew Bible may evince similar semantic configurations as found in the Book of Job.
