Modeling Dynamical Noises Corrupted Chaotic System for Heart Rate Variability Analysis

It is difficult to establish the process of chaos in time series from cardiac dynamics. The output from such a system is probably the result of both its internal dynamics, and the input to the system from its surroundings. We present an optimization algorithm to find a time series that is as close as possible to the heart rate series subject to the constraint that it is deterministic with respect to some dynamics. The algorithm is tested by some famous forced dynamical systems, and applied to heart rate data. We find that the deterministic components of heart rate variability are chaotic.

压阻式加速度计测量人体运动的探讨

本文探讨对压阻式加速度计所测得的人体加速度信号进行处理以估计人在体力活动中能耗的方法。受试者为12名青年女子。试验是在电动实验台上以3.7～5.9公里的时速步行。加速度计成对安装在后腰部,分别处于X轴(前后)和Z轴(上下)方向上。受试人步行中消耗的氧气被同步测得作为能耗的度量。数据采集与处理由一台386微机完成。实验表明运用压阻式传感器作为运动传感器可望在测能耗的同时估计身体的方向及其他运动特征。比较数据处理的方法按其与能耗之间的相关系数γ值来衡量。三种修正方法即基线法、参考法和不修正,当以加速度的RMS值作为测量参数时γ~2值分别为0.79,0.75和0.01,而三种测量参数即RMS、均值和峰值当以基线法对数据修正时γ~2值分别为0.79,0.79和0.70,步行中引入负重及上坡等条件时,加速度相对于能耗γ的~2值呈一致下降之势而不管采用何种测量参数或数据修正方式。比较表明,三种修正方式中以基线法最好;三种测量参数中RMS值和均值都优于峰值。