本研究旨在模拟不同狭窄程度和脉搏率的颈动脉搏动血流。采用流-固耦合(FSI)和任意拉格朗日-欧拉(ALE)方法研究了不同狭窄程度、脉搏率和动脉壁性质对周围流体的影响。分别应用Carreau-Yasuda非牛顿超弹性模型和修正Mooney-Rivin超弹性...本研究旨在模拟不同狭窄程度和脉搏率的颈动脉搏动血流。采用流-固耦合(FSI)和任意拉格朗日-欧拉(ALE)方法研究了不同狭窄程度、脉搏率和动脉壁性质对周围流体的影响。分别应用Carreau-Yasuda非牛顿超弹性模型和修正Mooney-Rivin超弹性模型于具有非牛顿行为的血液和超弹性血管壁。结果得到血液的壁面径向位移、压力分布、轴向速度分布和壁面剪切应力。通过增加狭窄的严重程度,轴向速度、血压变化、最大壁面剪切应力和壁面径向位移均呈增长趋势。当脉率在狭窄程度为75%时,最大流量矩、壁面径向位移、压力、轴向速度和壁面剪应力的最大值均增大。此外,与弹性和刚性模型相比,将动脉壁视为超弹性模型,将其周围流体视为非牛顿和非定常,可以使模拟更加真实。在严重程度高达50%的狭窄中,红细胞受到轻微损害,而在严重程度为75%的狭窄中观察到溶血。通过改善动脉粥样硬化,弹性模量从500 k Pa提高到2 MPa,在60 bpm脉率和狭窄程度75%下,剪切应力最大值增长65%。与刚性和弹性动脉壁相比,动脉壁的超弹性模型导致较低的轴向速度、较低的血压、较低的剪切应力和较高的径向位移。展开更多
Glitch activity refers to the mean increase in pulsar spin frequency per year due to rotational glitches.It is an important tool for studying super-nuclear matter using neutron star interiors as templates.Glitch event...Glitch activity refers to the mean increase in pulsar spin frequency per year due to rotational glitches.It is an important tool for studying super-nuclear matter using neutron star interiors as templates.Glitch events are typically observed in the spin frequency(ν) and frequency derivative( ν) of pulsars.The rate of glitch recurrence decreases as the pulsar ages,and the activity parameter is usually measured by linear regression of cumulative glitches over a given period.This method is effective for pulsars with multiple regular glitch events.However,due to the scarcity of glitch events and the difficulty of monitoring all known pulsars,only a few have multiple records of glitch events.This limits the use of the activity parameter in studying neutron star interiors with multiple pulsars.In this study,we examined the relationship between the activity parameters and pulsar spin parameters(spin frequency,frequency derivative,and pulsar characteristic age).We found that a quadratic function provides a better fit for the relationship between activity parameters and spin parameters than the commonly used linear functions.Using this information,we were able to estimate the activity parameters of other pulsars that do not have records of glitches.Our analysis shows that the relationship between the estimated activity parameters and pulsar spin parameters is consistent with that of the observed activity parameters in the ensemble of pulsars.展开更多
文摘本研究旨在模拟不同狭窄程度和脉搏率的颈动脉搏动血流。采用流-固耦合(FSI)和任意拉格朗日-欧拉(ALE)方法研究了不同狭窄程度、脉搏率和动脉壁性质对周围流体的影响。分别应用Carreau-Yasuda非牛顿超弹性模型和修正Mooney-Rivin超弹性模型于具有非牛顿行为的血液和超弹性血管壁。结果得到血液的壁面径向位移、压力分布、轴向速度分布和壁面剪切应力。通过增加狭窄的严重程度,轴向速度、血压变化、最大壁面剪切应力和壁面径向位移均呈增长趋势。当脉率在狭窄程度为75%时,最大流量矩、壁面径向位移、压力、轴向速度和壁面剪应力的最大值均增大。此外,与弹性和刚性模型相比,将动脉壁视为超弹性模型,将其周围流体视为非牛顿和非定常,可以使模拟更加真实。在严重程度高达50%的狭窄中,红细胞受到轻微损害,而在严重程度为75%的狭窄中观察到溶血。通过改善动脉粥样硬化,弹性模量从500 k Pa提高到2 MPa,在60 bpm脉率和狭窄程度75%下,剪切应力最大值增长65%。与刚性和弹性动脉壁相比,动脉壁的超弹性模型导致较低的轴向速度、较低的血压、较低的剪切应力和较高的径向位移。
文摘Glitch activity refers to the mean increase in pulsar spin frequency per year due to rotational glitches.It is an important tool for studying super-nuclear matter using neutron star interiors as templates.Glitch events are typically observed in the spin frequency(ν) and frequency derivative( ν) of pulsars.The rate of glitch recurrence decreases as the pulsar ages,and the activity parameter is usually measured by linear regression of cumulative glitches over a given period.This method is effective for pulsars with multiple regular glitch events.However,due to the scarcity of glitch events and the difficulty of monitoring all known pulsars,only a few have multiple records of glitch events.This limits the use of the activity parameter in studying neutron star interiors with multiple pulsars.In this study,we examined the relationship between the activity parameters and pulsar spin parameters(spin frequency,frequency derivative,and pulsar characteristic age).We found that a quadratic function provides a better fit for the relationship between activity parameters and spin parameters than the commonly used linear functions.Using this information,we were able to estimate the activity parameters of other pulsars that do not have records of glitches.Our analysis shows that the relationship between the estimated activity parameters and pulsar spin parameters is consistent with that of the observed activity parameters in the ensemble of pulsars.
