In this paper. based on the discussion of properties of the turbulent coherentstructure for smooth boumdary layer. a physical model has been established. The widthof slowly-moving streak line and bursting time of cohe...In this paper. based on the discussion of properties of the turbulent coherentstructure for smooth boumdary layer. a physical model has been established. The widthof slowly-moving streak line and bursting time of coherent structure expressed bymomentum thickness Reynolds mumber of boundary layer layer have been obtained,whichare in agreement with The experimental data￣[ 3. 4. 5.7 ]展开更多
Synthetic vascular grafts suitable for small-diameter arteries(<6 mm) are in great need.However,there are still no commercially available small-diameter vascular grafts(SDVGs) in clinical practice due to thrombosis...Synthetic vascular grafts suitable for small-diameter arteries(<6 mm) are in great need.However,there are still no commercially available small-diameter vascular grafts(SDVGs) in clinical practice due to thrombosis and stenosis after in vivo implantation.When designing SDVGs,many studies emphasized reendothelization but ignored the importance of reconstruction of the smooth muscle layer(SML).To facilitate rapid SML regeneration,a high-resolution 3D printing method was used to create a novel bilayer SDVG with structures and mechanical properties mimicking natural arteries.Bioinspired by the collagen alignment of SML,the inner layer of the grafts had larger pore sizes and high porosity to accelerate the infiltration of cells and their circumferential alignment,which could facilitate SML reconstruction for compliance restoration and spontaneous endothelialization.The outer layer was designed to induce fibroblast recruitment by low porosity and minor pore size and provide SDVG with sufficient mechanical strength.One month after implantation,the arteries regenerated by 3D-printed grafts exhibited better pulsatility than electrospun grafts,with a compliance(8.9%) approaching that of natural arteries(11.36%) and significantly higher than that of electrospun ones(1.9%).The 3D-printed vascular demonstrated a three-layer structure more closely resembling natural arteries while electrospun grafts showed incomplete endothelium and immature SML.Our study shows the importance of SML reconstruction during vascular graft regeneration and provides an effective strategy to reconstruct blood vessels through 3D-printed structures rapidly.展开更多
Bionic non-smooth surfaces （BNSS） can reduce drag. Much attention has been paid to the mechanism of shear stress reduction by riblets. The mechanism of pressure force reduction by bionic non-smooth surfaces on bodie...Bionic non-smooth surfaces （BNSS） can reduce drag. Much attention has been paid to the mechanism of shear stress reduction by riblets. The mechanism of pressure force reduction by bionic non-smooth surfaces on bodies of revolution has not been well investigated. In this work CFD simulation has revealed the mechanism of drag reduction by BNSS, which may work in three ways. First, BNSS on bodies of revolution may lower the surface velocity of the medium, which prevents the sudden speed up of air on the cross section. So the bottom pressure of the model would not be disturbed sharply, resulting in less energy loss and drag reduction. Second, the magnitude of vorticity induced by the bionic model becomes smaller because, due to the sculpturing, the growth of tiny air bubbles is avoided. Thus the large moment of inertia induced by large air bubble is reduced. The reduction of the vorticity could reduce the dissipation of the eddy. So the pressure force could also be reduced. Third, the thickness of the momentum layer on the model becomes less which, according to the relationship between the drag coefficient and the momentum thickness, reduces drag.展开更多
This study investigates the effectiveness of the non-smooth semi-active control algorithm on suppressing the vibration performance of a building structure subjected to seismic waves. According to the Lyapunov stabilit...This study investigates the effectiveness of the non-smooth semi-active control algorithm on suppressing the vibration performance of a building structure subjected to seismic waves. According to the Lyapunov stability theory, it has bene proven that the non-smooth semi-active control algorithm can achieve a finite-time stability of the vibration relative to the isolation layer of a building structure. Through numerical simulation of two buildings with different parameters subjected to the input of a seismic wave, the vibration conditions of passive control, LQR semi-active control and non-smooth semiactive control are compared and analyzed. The simulation results show that the non-smooth semi-active control algorithm has a better robustness and effectiveness in restraining the impact of earthquakes on the structure.展开更多
This paper presents the influences of plasma layer on the oscillatory flow inarterial stenosis. The analysis demonstrates that the existence of the plasma layer mayobviously change the characteristics of flow such as ...This paper presents the influences of plasma layer on the oscillatory flow inarterial stenosis. The analysis demonstrates that the existence of the plasma layer mayobviously change the characteristics of flow such as velocity-profiles, longitudinalimpedance and pressure gradient, but hardly change the phase of longitudinalimpedance and pressure gradient. Besides. such influences vary with a and degree ofstenosis. These analyses have Special physiological significance in blood circulationsystem.展开更多
文摘In this paper. based on the discussion of properties of the turbulent coherentstructure for smooth boumdary layer. a physical model has been established. The widthof slowly-moving streak line and bursting time of coherent structure expressed bymomentum thickness Reynolds mumber of boundary layer layer have been obtained,whichare in agreement with The experimental data￣[ 3. 4. 5.7 ]
基金sponsored by the National Natural Science Foundation of China (Nos.52235007, 52325504, T2121004)Zhejiang Province Natural Science Foundation of China under Grant No.LQ23H090012, LQ22H180001the Science and Technology of Medicine and Health program of Zhejiang Province (No.2023RC028)。
文摘Synthetic vascular grafts suitable for small-diameter arteries(<6 mm) are in great need.However,there are still no commercially available small-diameter vascular grafts(SDVGs) in clinical practice due to thrombosis and stenosis after in vivo implantation.When designing SDVGs,many studies emphasized reendothelization but ignored the importance of reconstruction of the smooth muscle layer(SML).To facilitate rapid SML regeneration,a high-resolution 3D printing method was used to create a novel bilayer SDVG with structures and mechanical properties mimicking natural arteries.Bioinspired by the collagen alignment of SML,the inner layer of the grafts had larger pore sizes and high porosity to accelerate the infiltration of cells and their circumferential alignment,which could facilitate SML reconstruction for compliance restoration and spontaneous endothelialization.The outer layer was designed to induce fibroblast recruitment by low porosity and minor pore size and provide SDVG with sufficient mechanical strength.One month after implantation,the arteries regenerated by 3D-printed grafts exhibited better pulsatility than electrospun grafts,with a compliance(8.9%) approaching that of natural arteries(11.36%) and significantly higher than that of electrospun ones(1.9%).The 3D-printed vascular demonstrated a three-layer structure more closely resembling natural arteries while electrospun grafts showed incomplete endothelium and immature SML.Our study shows the importance of SML reconstruction during vascular graft regeneration and provides an effective strategy to reconstruct blood vessels through 3D-printed structures rapidly.
基金National Natural Science Foundation of China （Grant No.50635030） the International Cooperation key Project of Ministry of Science and Technology of China （Grant No. 2005DFA00850）+2 种基金 The key project about ministry of education of science and technology （Grant No. 105059） the international cooperative of Jilin Province （Grant No.20040703-1） Specialized Research fund for the Doctoral Program of higher Education （Grant No. 20050183064）.
文摘Bionic non-smooth surfaces （BNSS） can reduce drag. Much attention has been paid to the mechanism of shear stress reduction by riblets. The mechanism of pressure force reduction by bionic non-smooth surfaces on bodies of revolution has not been well investigated. In this work CFD simulation has revealed the mechanism of drag reduction by BNSS, which may work in three ways. First, BNSS on bodies of revolution may lower the surface velocity of the medium, which prevents the sudden speed up of air on the cross section. So the bottom pressure of the model would not be disturbed sharply, resulting in less energy loss and drag reduction. Second, the magnitude of vorticity induced by the bionic model becomes smaller because, due to the sculpturing, the growth of tiny air bubbles is avoided. Thus the large moment of inertia induced by large air bubble is reduced. The reduction of the vorticity could reduce the dissipation of the eddy. So the pressure force could also be reduced. Third, the thickness of the momentum layer on the model becomes less which, according to the relationship between the drag coefficient and the momentum thickness, reduces drag.
基金National Natural Science Foundation(NNSF)of China under Grant No.51478132Guangzhou City College Scientific Research Project under Grant No.120163017
文摘This study investigates the effectiveness of the non-smooth semi-active control algorithm on suppressing the vibration performance of a building structure subjected to seismic waves. According to the Lyapunov stability theory, it has bene proven that the non-smooth semi-active control algorithm can achieve a finite-time stability of the vibration relative to the isolation layer of a building structure. Through numerical simulation of two buildings with different parameters subjected to the input of a seismic wave, the vibration conditions of passive control, LQR semi-active control and non-smooth semiactive control are compared and analyzed. The simulation results show that the non-smooth semi-active control algorithm has a better robustness and effectiveness in restraining the impact of earthquakes on the structure.
文摘This paper presents the influences of plasma layer on the oscillatory flow inarterial stenosis. The analysis demonstrates that the existence of the plasma layer mayobviously change the characteristics of flow such as velocity-profiles, longitudinalimpedance and pressure gradient, but hardly change the phase of longitudinalimpedance and pressure gradient. Besides. such influences vary with a and degree ofstenosis. These analyses have Special physiological significance in blood circulationsystem.
