\r金龙哲，王梦飞，于 露，徐明伟\r
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AuthorsHTML:\r金龙哲，王梦飞，于 露，徐明伟\r
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AuthorsListE:\rJin Longzhe，Wang Mengfei，Yu Lu，Xu Mingwei\r
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AuthorsHTMLE:\rJin Longzhe，Wang Mengfei，Yu Lu，Xu Mingwei\r
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Unit:\r北京科技大学土木与资源工程学院，北京 100083\r
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Unit_EngLish:\rSchool of Civil and Resource Engineering，University of Science and Technology Beijing，Beijing 100083，China\r
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Abstract_Chinese:\r工业化迅速发展使得有限空间作业增多，有限空间作业人员在极限低氧环境(环境氧气浓度低于15%)下易受到低氧伤害，传统的环境氧浓度监测预警未考虑作业人员个体生理状态的差异性．本文针对作业人员生理状态的不同提出一种快速准确的特异性低氧伤害评估预警方法．通过智能穿戴设备监测正常氧浓度(20%～21%)和人体可耐受最低氧浓度(15%～16%)情况下的人体光电容积脉搏波(photoplethysmography)信号，采用振幅和基波频率差异作为依据，对作业人员进行快速准确实时的低氧伤害评估及预警．本文在信号处理过程中利用小波变换和移动平均滤波器去除基线漂移和高频噪声，获得高信噪比的信号并进行时域分析，继而通过快速傅里叶变换将处理后的高信噪比信号进行转换获得频谱图进行频域分析．时域分析与频域分析的结果表明：低氧环境中，人体光电容积脉搏波信号的振幅和基波频率较正常氧浓度情况下均存在显著性差异(p＜0.05)，下降率的平均值分别为46%和19%；利用极大似然估计法和3 σ 原则计算下降率的临界值，确定振幅和基波频率下降率的临界值分别为29%和8.6%，该临界值的理论计算准确度为84.1%；利用计算所得的临界值建立有限空间低氧伤害评估预警表．该评估表的理论准确度为97.5%，经实验验证其预警成功率为91%且无漏报情况发生．\r
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Abstract_English:\rThe rapid development of industrialization has increased the number of confined space operations. Confined space workers are vulnerable to hypoxic injury under an extreme hypoxic environment，where oxygen concentration
is less than 15%．The traditional monitoring and early warning system of environmental oxygen concentration does not consider the differences among the individual physiological status of the operators．In this study，a new
rapid and accurate early warning method for specific hypoxic injury assessment was proposed according to the different physiological status of the workers．By monitoring the normal oxygen concentration(20%—21%)and the lowest tolerable oxygen concentration(15%—16%)via intelligent wearable equipment，the photoplethysmography signal of the human body was detected，and the differences of the amplitude and fundamental frequency were used for rapid，accurate，and real-time assessment and early warning of hypoxic injury to workers．Herein，we used the wavelet transform and a moving average filter to remove the baseline drift and high-frequency noise in signal processing，obtain a high signal-to-noise ratio(SNR)signal and analyze it in time domain，and then transform the processed high SNR signal into the frequency domain using a fast Fourier transform(FFT)．The results of time-domain analysis and frequency-domain analysis show that there are significant differences in the amplitude and fundamental frequency of the human photoelectric volume pulse wave signal in a hypoxic environment compared with that in an environment with normal oxygen concentration(p＜0.05)．The average decline rate in amplitude and fundamental frequency is 46% and 19%．The critical value of the decline rate is calculated by maximum likelihood estimation method and the principle of 3σ，the critical points of the decline rates of the amplitude and fundamental frequency are determined as 29% and 8.6%，respectively，and the theoretical accuracy of the critical value is 84.1%．A confined space hypoxic injury assessment and early warning table is established based on the calculated critical value．The theoretical accuracy of the evaluation table is 97.5%．The experimental results show that the accuracy rate of early warning is 91% and that there is no false negative．\r
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Keyword_Chinese:低氧伤害；光电容积脉搏波；有限空间；评估预警；时域分析；频域分析\r

Keywords_English:hypoxic injury；photoplethysmography(PPG)；confined space；evaluation and early warning；timedomain analysis；frequency-domain analysis\r


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