The objective of this paper is to study the nonlinear coupling internal resonance of the heave,roll,and pitch response performance of a spar platform when their frequencies are in the ratio of 2:1:1 under wave and vor...The objective of this paper is to study the nonlinear coupling internal resonance of the heave,roll,and pitch response performance of a spar platform when their frequencies are in the ratio of 2:1:1 under wave and vortex exciting loads.The three degree-of-freedom(DOF)nonlinear coupled equations are established by considering a time-varying wet surface with a first-order wave force in heave and pitch and a vortex-induced force in roll.The first-order steady-state response is solved using the multi-scale method in heave main resonance.The multiple solutions of the motion equations are discussed using the analytic method and a numerical simulation.A sensitivity analysis is conducted to test the influence of the damping and internal detuning parameter.The regions of multiple solutions are found,and the jump phenomenon exists with the changes of the wave excitation.The regions of multiple solutions depend on the values of damping and detuning parameter.展开更多
Tropical cyclones are large-scale strong wind disturbance events that occur frequently in tropical and subtropical coastal regions and often bring catastrophic physical destruction to ecosystems and economic disruptio...Tropical cyclones are large-scale strong wind disturbance events that occur frequently in tropical and subtropical coastal regions and often bring catastrophic physical destruction to ecosystems and economic disruption to societies along their paths. Major tropical cyclones can infrequently move into the midaltitudes and inland areas. Ecologically, tropical cyclones have profound impacts on diversity, structure, succession and function of forest ecosystems. The ecological effects are both dramatic and subtle. The dramatic effects can be visible, noticeable and to some extent predictable over the short-term and relatively well documented in the literature. However, the subtle effects are often invisible, complex and at smaller scale relatively unpredictable in the long-term. Many factors, meteorologic, topographic and biologic, simultaneously interact to influence the complexity of patterns of damage and dynamics of recovery. I present a global synthesis on the effects of tropical cyclones on forest ecosystems and the complexity of forest responses, with particular attention on the response to large hurricanes in the neotropics and the temperate North America, and strong typhoons on the subtropical and temperate forests in the East and Southeast Asia. Four major aspects provide on organizational framework for this synthesis：（1） consistent damage patterns,（2） factors that influence response patterns and predict damage risks,（3） complexity of forest responses and recovery, and（4） the long-term effects. This review reveals highly variable and complex effects of tropical cyclones on forest ecosystems. A deep understanding of the synergistic effects of tropical cyclones is essential for effective forest management and biodiversity conservation.展开更多
In this paper, problems of the flow over a fat plate in the large Reynolds numbercase are studied by using the method of multiple scales￣[1,2].We have obtained N-orderuniformly valid asymptotic solutions of the Naver...In this paper, problems of the flow over a fat plate in the large Reynolds numbercase are studied by using the method of multiple scales￣[1,2].We have obtained N-orderuniformly valid asymptotic solutions of the Naver-Stodes equations.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.51279130
文摘The objective of this paper is to study the nonlinear coupling internal resonance of the heave,roll,and pitch response performance of a spar platform when their frequencies are in the ratio of 2:1:1 under wave and vortex exciting loads.The three degree-of-freedom(DOF)nonlinear coupled equations are established by considering a time-varying wet surface with a first-order wave force in heave and pitch and a vortex-induced force in roll.The first-order steady-state response is solved using the multi-scale method in heave main resonance.The multiple solutions of the motion equations are discussed using the analytic method and a numerical simulation.A sensitivity analysis is conducted to test the influence of the damping and internal detuning parameter.The regions of multiple solutions are found,and the jump phenomenon exists with the changes of the wave excitation.The regions of multiple solutions depend on the values of damping and detuning parameter.
基金supported by National Natural Science Foundation of China(31370483)a University Research Award from Texas A&M University-Kingsville
文摘Tropical cyclones are large-scale strong wind disturbance events that occur frequently in tropical and subtropical coastal regions and often bring catastrophic physical destruction to ecosystems and economic disruption to societies along their paths. Major tropical cyclones can infrequently move into the midaltitudes and inland areas. Ecologically, tropical cyclones have profound impacts on diversity, structure, succession and function of forest ecosystems. The ecological effects are both dramatic and subtle. The dramatic effects can be visible, noticeable and to some extent predictable over the short-term and relatively well documented in the literature. However, the subtle effects are often invisible, complex and at smaller scale relatively unpredictable in the long-term. Many factors, meteorologic, topographic and biologic, simultaneously interact to influence the complexity of patterns of damage and dynamics of recovery. I present a global synthesis on the effects of tropical cyclones on forest ecosystems and the complexity of forest responses, with particular attention on the response to large hurricanes in the neotropics and the temperate North America, and strong typhoons on the subtropical and temperate forests in the East and Southeast Asia. Four major aspects provide on organizational framework for this synthesis：（1） consistent damage patterns,（2） factors that influence response patterns and predict damage risks,（3） complexity of forest responses and recovery, and（4） the long-term effects. This review reveals highly variable and complex effects of tropical cyclones on forest ecosystems. A deep understanding of the synergistic effects of tropical cyclones is essential for effective forest management and biodiversity conservation.
文摘In this paper, problems of the flow over a fat plate in the large Reynolds numbercase are studied by using the method of multiple scales￣[1,2].We have obtained N-orderuniformly valid asymptotic solutions of the Naver-Stodes equations.
