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Adaptive positioning control of guyed offshore towers through active mass dampers
No full textلقد تم في هذا البحث اقتراح مضائل اهتزازي آتلي قابل للتكيف لتثبيت حرآة شداد بنيان مغموس في
محيط انسيابي. وقد تم اشتقاق المعادلة الثلاثية الأبعاد التي تصف حرآة البنيان وتحتوي على مضائل
آتلي موالف من مبدأ هاميلتون الكلاسيكي. آما استخدم لوصف النظام الحرآي نموذج ذو رتبة مقلّلة
ومنعزلة يحمل حرية حرآة رباعية. ولتمثيل التفاعل بين المحيط الانسيابي والبنيان تم استخدام معادلات
موريسون بإضافة الحدود بما في ذلك تأثير الدوامة الحرآية. وقد تم إدراك استراتيجية التحكم من خلال
مضائل آتلي موالف مثبت على البنيان ومشتق بوساطة لوغرثم التحكم الانضباطي. وخلال عملية
التحكم تم السماح لعدد من المعامل الهيدروديناميكية بأخذ قيم غير محددة. والطريقة المقترحة في هذه
الدراسة تشتمل على نتيجتين متميزتين ومفيدتين؛ الأولى هي التحكم في اهتزاز البنيان، والثانية هي
تقدير المعامل الهيدروديناميكية، إضافة إلى اثبات وتعيير نموذج معادلة موريسون للانسياب المحدث
للقوى.An adaptive mass damper is proposed to stabilize the motion of a guyed structure
immersed in a flow field. The equations describing the 3D motion of the structure
equipped with a tuned mass damper are derived by classical Hamiltonian principles.
A 4-DOF discrete reduced-order model is assumed to describe the system. Morison’s
equations are used to represent the interaction between the flow field and the structure,
complemented by terms including the vortex dynamics effect. The control strategy is
realized through a tuned mass damper attached to the structure and driven by an
adaptive control algorithm. During the control activity, uncertainty in the various
hydrodynamic coefficients is allowed. The proposed procedures have two distinct
beneficial results. The first one being to control the vibration of the structure, and the
second one is the estimation of the hydrodynamic coefficients and the validation/
calibration of Morison’s equation model for the flow-induced forces
Position and flexural control of an offshore structure in the presence of uncertain dynamics
No full textAdaptive control of flow-induced vibrations including vortex effects
No full textFlow-induced vibrations constitute important design criteria for most offshore structures as well as for many other structures subjected to flow-induced forces. Both the main structural elements as well as supporting structural members such as guyed cables must be designed to withstand such oscillations. It is well established that in the process of vibrations induced by flow, vortices form around the body which initiate oscillations in a direction transverse to the general direction of motion. In this paper, Morison's equation is used to represent the interaction between the flow field and the structure, complemented by terms including the vortex dynamics effect. In order to mitigate against extreme vibration conditions, here, the implementation of active control is proposed to stabilize the motion of a structure immersed in a flow field. Specifically, a tuned mass damper is attached to the structure and adaptive control is utilized for moving the mass along a particular path while allowing for uncertainty in the various hydrodynamic coefficients. The proposed procedure have two distinct beneficial results. The first one being to control the vibration of the structure, and the second one is the estimation of the hydrodynamic coefficients and the validation/calibration of Morison's equation model for the flow-induced forces
Adaptive positioning control of guyed offshore towers through active mass dampers
No full textلقد تم في هذا البحث اقتراح مضائل اهتزازي آتلي قابل للتكيف لتثبيت حرآة شداد بنيان مغموس في
محيط انسيابي. وقد تم اشتقاق المعادلة الثلاثية الأبعاد التي تصف حرآة البنيان وتحتوي على مضائل
آتلي موالف من مبدأ هاميلتون الكلاسيكي. آما استخدم لوصف النظام الحرآي نموذج ذو رتبة مقلّلة
ومنعزلة يحمل حرية حرآة رباعية. ولتمثيل التفاعل بين المحيط الانسيابي والبنيان تم استخدام معادلات
موريسون بإضافة الحدود بما في ذلك تأثير الدوامة الحرآية. وقد تم إدراك استراتيجية التحكم من خلال
مضائل آتلي موالف مثبت على البنيان ومشتق بوساطة لوغرثم التحكم الانضباطي. وخلال عملية
التحكم تم السماح لعدد من المعامل الهيدروديناميكية بأخذ قيم غير محددة. والطريقة المقترحة في هذه
الدراسة تشتمل على نتيجتين متميزتين ومفيدتين؛ الأولى هي التحكم في اهتزاز البنيان، والثانية هي
تقدير المعامل الهيدروديناميكية، إضافة إلى اثبات وتعيير نموذج معادلة موريسون للانسياب المحدث
للقوى.An adaptive mass damper is proposed to stabilize the motion of a guyed structure
immersed in a flow field. The equations describing the 3D motion of the structure
equipped with a tuned mass damper are derived by classical Hamiltonian principles.
A 4-DOF discrete reduced-order model is assumed to describe the system. Morison’s
equations are used to represent the interaction between the flow field and the structure,
complemented by terms including the vortex dynamics effect. The control strategy is
realized through a tuned mass damper attached to the structure and driven by an
adaptive control algorithm. During the control activity, uncertainty in the various
hydrodynamic coefficients is allowed. The proposed procedures have two distinct
beneficial results. The first one being to control the vibration of the structure, and the
second one is the estimation of the hydrodynamic coefficients and the validation/
calibration of Morison’s equation model for the flow-induced forces
Adaptive control of flow-induced vibrations including vortex effects
No full textFlow-induced vibrations constitute important design criteria for most offshore structures as well as for many other structures subjected to flow-induced forces. Both the main structural elements as well as supporting structural members such as guyed cables must be designed to withstand such oscillations. It is well established that in the process of vibrations induced by flow, vortices form around the body which initiate oscillations in a direction transverse to the general direction of motion. In this paper, Morison's equation is used to represent the interaction between the flow field and the structure, complemented by terms including the vortex dynamics effect. In order to mitigate against extreme vibration conditions, here, the implementation of active control is proposed to stabilize the motion of a structure immersed in a flow field. Specifically, a tuned mass damper is attached to the structure and adaptive control is utilized for moving the mass along a particular path while allowing for uncertainty in the various hydrodynamic coefficients. The proposed procedure have two distinct beneficial results. The first one being to control the vibration of the structure, and the second one is the estimation of the hydrodynamic coefficients and the validation/calibration of Morison's equation model for the flow-induced forces
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