为了提高无创血压连续测量的便捷性和准确度,提出了一种基于脉搏波传导时间(PTT)的头戴式血压测量方法,该方法将光电容积脉搏波(PPG)信号和心电(ECG)信号的采集集中在头部,将PPG信号一阶微分最大点与ECG信号R波峰的时间差值作为脉搏波...为了提高无创血压连续测量的便捷性和准确度,提出了一种基于脉搏波传导时间(PTT)的头戴式血压测量方法,该方法将光电容积脉搏波(PPG)信号和心电(ECG)信号的采集集中在头部,将PPG信号一阶微分最大点与ECG信号R波峰的时间差值作为脉搏波传导时间,并在血压的计算中加入了卡尔曼滤波器。实验结果表明,利用改进方法计算出的血压值平均误差率在5%以内,数据误差均在10 mm Hg以内,能够满足连续血压测量误差的要求;与传统方法相比,稳定性更好,误差率更小,最大误差更小。展开更多
为了检测公安、消防官兵等高危职业人群的心电信号,以胸带作为穿戴载体,设计一款可穿戴式无线心电检测系统,在智能手机上实现心电、心率的实时传输与显示。考虑到警员日常的活动,基于自适应滤波器原理,将三轴加速度传感器作为参考信号,...为了检测公安、消防官兵等高危职业人群的心电信号,以胸带作为穿戴载体,设计一款可穿戴式无线心电检测系统,在智能手机上实现心电、心率的实时传输与显示。考虑到警员日常的活动,基于自适应滤波器原理,将三轴加速度传感器作为参考信号,对比两种自适应滤波算法滤出运动伪迹(Motion Artifact,MA)后的输出波形。结果表明,采用归一化的最小均方算法(Normalized Least Mean Square,NLMS)的自适应滤波器输出心电信号基线平稳且R波定位准确性达99%以上。在正常的人体活动中实时测量的心率值误差在4%以内,心率测量精度较高。展开更多
The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles a...The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles and surrounding tissues.Therefore, the cavitation dynamics and resultant mechanical stress of two-interacting bubbles in the viscoelastic tissues are numerically investigated, especially focusing on the effects of the adjacent bubble. The results demonstrate that the mechanical stress is highly dependent on the bubble dynamics. The compressive stress and tensile stress are generated at the stage of bubble expansion and collapse stage, respectively. Furthermore, within the initial parameters examined in this paper, the effects of the adjacent bubble will distinctly suppress the radial expansion of the small bubble and consequently lead its associated stresses to decrease. Owing to the superimposition of two stress fields, the mechanical stresses surrounding the small bubble in the direction of the neighboring bubble are smaller than those in other directions. For two interacting cavitation bubbles, the suppression effects of the nearby bubble on both the cavitation dynamics and the stresses surrounding the small bubble increase as the ultrasound amplitude and the initial radius of the large bubble increase, whereas they decrease with the inter-bubble distance increasing. Moreover, increasing the tissue viscoelasticity will reduce the suppression effects of the nearby bubble, except in instances where the compressive stress and tensile stress first increase and then decrease with the tissue elasticity and viscosity increasing respectively. This study can provide a further understanding of the mechanisms of cavitation-associated mechanical damage to the adjacent tissues or cells.展开更多
文摘为了提高无创血压连续测量的便捷性和准确度,提出了一种基于脉搏波传导时间(PTT)的头戴式血压测量方法,该方法将光电容积脉搏波(PPG)信号和心电(ECG)信号的采集集中在头部,将PPG信号一阶微分最大点与ECG信号R波峰的时间差值作为脉搏波传导时间,并在血压的计算中加入了卡尔曼滤波器。实验结果表明,利用改进方法计算出的血压值平均误差率在5%以内,数据误差均在10 mm Hg以内,能够满足连续血压测量误差的要求;与传统方法相比,稳定性更好,误差率更小,最大误差更小。
文摘为了检测公安、消防官兵等高危职业人群的心电信号,以胸带作为穿戴载体,设计一款可穿戴式无线心电检测系统,在智能手机上实现心电、心率的实时传输与显示。考虑到警员日常的活动,基于自适应滤波器原理,将三轴加速度传感器作为参考信号,对比两种自适应滤波算法滤出运动伪迹(Motion Artifact,MA)后的输出波形。结果表明,采用归一化的最小均方算法(Normalized Least Mean Square,NLMS)的自适应滤波器输出心电信号基线平稳且R波定位准确性达99%以上。在正常的人体活动中实时测量的心率值误差在4%以内,心率测量精度较高。
基金Project supported by the National Natural Science Foundation of China (Grant No.11904042)the Natural Science Foundation of Chongqing,China (Grant No.cstc2019jcyj-msxmX0534)the Science and Technology Research Program of Chongqing Municipal Education Commission,China (Grant No.KJQN202000617)。
文摘The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles and surrounding tissues.Therefore, the cavitation dynamics and resultant mechanical stress of two-interacting bubbles in the viscoelastic tissues are numerically investigated, especially focusing on the effects of the adjacent bubble. The results demonstrate that the mechanical stress is highly dependent on the bubble dynamics. The compressive stress and tensile stress are generated at the stage of bubble expansion and collapse stage, respectively. Furthermore, within the initial parameters examined in this paper, the effects of the adjacent bubble will distinctly suppress the radial expansion of the small bubble and consequently lead its associated stresses to decrease. Owing to the superimposition of two stress fields, the mechanical stresses surrounding the small bubble in the direction of the neighboring bubble are smaller than those in other directions. For two interacting cavitation bubbles, the suppression effects of the nearby bubble on both the cavitation dynamics and the stresses surrounding the small bubble increase as the ultrasound amplitude and the initial radius of the large bubble increase, whereas they decrease with the inter-bubble distance increasing. Moreover, increasing the tissue viscoelasticity will reduce the suppression effects of the nearby bubble, except in instances where the compressive stress and tensile stress first increase and then decrease with the tissue elasticity and viscosity increasing respectively. This study can provide a further understanding of the mechanisms of cavitation-associated mechanical damage to the adjacent tissues or cells.
