Elovicb, two-constant, parabolic diffusion, exponential, second-order, first-order and zero-order equations were used to describe the kinetic characteristics of potassium desorption from six paddy soils df Zhejiang Pr...Elovicb, two-constant, parabolic diffusion, exponential, second-order, first-order and zero-order equations were used to describe the kinetic characteristics of potassium desorption from six paddy soils df Zhejiang Province in a constant electric field (44.4 V/ cm) of EUF. Results showed that the second-order and Elovich equations could describe the potassium desorption kinetics best, as evidenced by the highest correlation coefficients (r) and the lowest standard errors (SE). The first-order, two-constant and parabolic diffusion equations also described the K desorption kinetics well, as showed by the relatively high correlation coefficients and relatively low standard errors. The zero-order equation did not describe the K desorption satisfactorily with a relatively low correlation coefficient and relatively high standard error. However, the exponential equation could not be used to describe the K desorption kinetics, due to the lowest correlation coefficient and the highest standard error.展开更多
In the context of this paper, a small scale, medium precision, stabilized pan/tilt platform is developed as a prototype, which is used to compare various stabilization algorithms experimentally. The overall performanc...In the context of this paper, a small scale, medium precision, stabilized pan/tilt platform is developed as a prototype, which is used to compare various stabilization algorithms experimentally. The overall performance of the system depends on rigid body dynamics, structural dynamics, servo control loops, stabilization control algorithm, sensor fusion algorithm and sensory feedback such as from the IMU （inertial measurement unit）. In the case that the response bandwidth of the overall system is high enough, the same hardware can also achieve active vibration isolation. All of these design aspects are investigated in the paper via numerical models and with their experimental verification.展开更多
Hemodynamic characteristics such as blood velocity,blood pressure,flow impingement,wall shear stress and oscillatory shear index are considered to play important roles in the initiation,growth,rupture and recurrence o...Hemodynamic characteristics such as blood velocity,blood pressure,flow impingement,wall shear stress and oscillatory shear index are considered to play important roles in the initiation,growth,rupture and recurrence of the cerebral aneurysms.Endovascular therapy is widely implemented to treat the cerebral aneurysms by releasing coils into the aneurysm sac for limiting the blood flow to the sac and stent-assisted coil embolization is adopted to occlude the wide-necked or complex aneurysms.Some researchers believe that stents are not only a mechanical device but may act as a biological system and contribute to vessel wall healing.Hemodynamics simulation helps people understand the effect of hemodynamic characteristics on the recurrence of the coiled aneurysm and it also benefits the interventional planning of neurosurgeons.This study constructed the numerical model for a subject-specific ICA aneurysm treated with stent-assisted coil embolization,which combined the coiled model of the aneurysm with a porous stent placement,and simulated the pulsatile blood flow in these aneurysm models.When a stent was placed across the aneurysm orifice in the coiled aneurysm,the high wall shear stress around the distal aneurysm root was reduced more than that of the coiled aneurysm without a stent.The simulated results point to the conclusion that the stent not only protects the parent artery from occlusion due to extension of coils or thrombosis,but may also reduce the recurrence risk of the stent-assisted coiled aneurysm.展开更多
文摘Elovicb, two-constant, parabolic diffusion, exponential, second-order, first-order and zero-order equations were used to describe the kinetic characteristics of potassium desorption from six paddy soils df Zhejiang Province in a constant electric field (44.4 V/ cm) of EUF. Results showed that the second-order and Elovich equations could describe the potassium desorption kinetics best, as evidenced by the highest correlation coefficients (r) and the lowest standard errors (SE). The first-order, two-constant and parabolic diffusion equations also described the K desorption kinetics well, as showed by the relatively high correlation coefficients and relatively low standard errors. The zero-order equation did not describe the K desorption satisfactorily with a relatively low correlation coefficient and relatively high standard error. However, the exponential equation could not be used to describe the K desorption kinetics, due to the lowest correlation coefficient and the highest standard error.
文摘In the context of this paper, a small scale, medium precision, stabilized pan/tilt platform is developed as a prototype, which is used to compare various stabilization algorithms experimentally. The overall performance of the system depends on rigid body dynamics, structural dynamics, servo control loops, stabilization control algorithm, sensor fusion algorithm and sensory feedback such as from the IMU （inertial measurement unit）. In the case that the response bandwidth of the overall system is high enough, the same hardware can also achieve active vibration isolation. All of these design aspects are investigated in the paper via numerical models and with their experimental verification.
基金supported by the National Natural Science Foundation of China (Grant Nos. 30772234 and 30870707)
文摘Hemodynamic characteristics such as blood velocity,blood pressure,flow impingement,wall shear stress and oscillatory shear index are considered to play important roles in the initiation,growth,rupture and recurrence of the cerebral aneurysms.Endovascular therapy is widely implemented to treat the cerebral aneurysms by releasing coils into the aneurysm sac for limiting the blood flow to the sac and stent-assisted coil embolization is adopted to occlude the wide-necked or complex aneurysms.Some researchers believe that stents are not only a mechanical device but may act as a biological system and contribute to vessel wall healing.Hemodynamics simulation helps people understand the effect of hemodynamic characteristics on the recurrence of the coiled aneurysm and it also benefits the interventional planning of neurosurgeons.This study constructed the numerical model for a subject-specific ICA aneurysm treated with stent-assisted coil embolization,which combined the coiled model of the aneurysm with a porous stent placement,and simulated the pulsatile blood flow in these aneurysm models.When a stent was placed across the aneurysm orifice in the coiled aneurysm,the high wall shear stress around the distal aneurysm root was reduced more than that of the coiled aneurysm without a stent.The simulated results point to the conclusion that the stent not only protects the parent artery from occlusion due to extension of coils or thrombosis,but may also reduce the recurrence risk of the stent-assisted coiled aneurysm.
