The spatial-temporal evolution of coherent structures(CS) is significant for turbulence control and drag reduction. Among the CS, low and high speed streak structures show typical burst phenomena. The analysis was bas...The spatial-temporal evolution of coherent structures(CS) is significant for turbulence control and drag reduction. Among the CS, low and high speed streak structures show typical burst phenomena. The analysis was based on a time series of three-dimensional and three-component(3D-3C) velocity fields of the flat plate turbulent boundary layer(TBL) measured by a Tomographic and Time-resolved PIV(Tomo TRPIV) system. Using multi-resolution wavelet transform and conditional sampling method, we extracted the intrinsic topologies and found that the streak structures appear in bar-like patterns. Furthermore, we seized locations and velocity information of transient CS, and then calculated the propagation velocity of CS based on spatial-temporal cross-correlation scanning. This laid a foundation for further studies on relevant dynamics properties.展开更多
Issue on illegal logging and related trade is a hot topic for the international community. It has brought the negative effects to the sustainable development on global society, economy and ecology, which is also one o...Issue on illegal logging and related trade is a hot topic for the international community. It has brought the negative effects to the sustainable development on global society, economy and ecology, which is also one of the main objectives of international cooperation to combat with. At present, subjects of international law play a decisive role in combating illegal logging and related trade. The subjects of international law generally refer to states, intergovernmental organizations (IGOs) and part of non-governmental organizations (NGOs), which can have an independent international legal personality, enjoy rights and assume obligations of international law. As a responsible big country of the international community and state member of intergovernmental organizations and international treaties of forest resources protection, China ought to fully perform the obligations of international law. In face of illegal logging and related trade around the world, China should rationally tackle with it, resolutely crack down on it, and finally choose the sustainable development strategy based on rule of law.展开更多
基金supported by the National Natural Science Foundation of China(11332006,11272233,and 11411130150)the National Basic Research Programm of China(2012CB720101)
文摘The spatial-temporal evolution of coherent structures(CS) is significant for turbulence control and drag reduction. Among the CS, low and high speed streak structures show typical burst phenomena. The analysis was based on a time series of three-dimensional and three-component(3D-3C) velocity fields of the flat plate turbulent boundary layer(TBL) measured by a Tomographic and Time-resolved PIV(Tomo TRPIV) system. Using multi-resolution wavelet transform and conditional sampling method, we extracted the intrinsic topologies and found that the streak structures appear in bar-like patterns. Furthermore, we seized locations and velocity information of transient CS, and then calculated the propagation velocity of CS based on spatial-temporal cross-correlation scanning. This laid a foundation for further studies on relevant dynamics properties.
文摘Issue on illegal logging and related trade is a hot topic for the international community. It has brought the negative effects to the sustainable development on global society, economy and ecology, which is also one of the main objectives of international cooperation to combat with. At present, subjects of international law play a decisive role in combating illegal logging and related trade. The subjects of international law generally refer to states, intergovernmental organizations (IGOs) and part of non-governmental organizations (NGOs), which can have an independent international legal personality, enjoy rights and assume obligations of international law. As a responsible big country of the international community and state member of intergovernmental organizations and international treaties of forest resources protection, China ought to fully perform the obligations of international law. In face of illegal logging and related trade around the world, China should rationally tackle with it, resolutely crack down on it, and finally choose the sustainable development strategy based on rule of law.
