Early detection of sudden cardiac death by using classical linear techniques and time-frequency methods on electrocardiogram signals

Early detection of sudden cardiac death may be used for surviving the life of cardiac patients. In this paper we have investigated an algorithm to detect and predict sudden cardiac death, by processing of heart rate variability signal through the classical and time-frequency methods. At first, one minute of ECG signals, just before the cardiac death event are extracted and used to compute heart rate variability (HRV) signal. Five features in time domain and four features in frequency domain are extracted from the HRV signal and used as classical linear features. Then the Wigner Ville transform is applied to the HRV signal, and 11 extra features in the time-frequency (TF) domain are obtained. In order to improve the performance of classification, the principal component analysis (PCA) is applied to the obtained features vector. Finally a neural network classifier is applied to the reduced features. The obtained results show that the TF method can classify normal and SCD subjects, more efficiently than the classical methods. A MIT-BIH ECG database was used to evaluate the proposed method. The proposed method was implemented using MLP classifier and had 74.36% and 99.16% correct detection rate (accuracy) for classical features and TF method, respectively. Also, the accuracy of the KNN classifier were 73.87% and 96.04%.

Preliminary abnormal electrocardiogram segment screening method for Holter data based on long short-term memory networks

Holter usually monitors electrocardiogram(ECG)signals for more than 24 hours to capture short-lived cardiac abnormalities.In view of the large amount of Holter data and the fact that the normal part accounts for the majority,it is reasonable to design an algorithm that can automatically eliminate normal data segments as much as possible without missing any abnormal data segments,and then take the left segments to the doctors or the computer programs for further diagnosis.In this paper,we propose a preliminary abnormal segment screening method for Holter data.Based on long short-term memory(LSTM)networks,the prediction model is established and trained with the normal data of a monitored object.Then,on the basis of kernel density estimation,we learn the distribution law of prediction errors after applying the trained LSTM model to the regular data.Based on these,the preliminary abnormal ECG segment screening analysis is carried out without R wave detection.Experiments on the MIT-BIH arrhythmia database show that,under the condition of ensuring that no abnormal point is missed,53.89% of normal segments can be effectively obviated.This work can greatly reduce the workload of subsequent further processing.

Identifying Possible Climate Change Signals Using Meteorological Parameters in Short-Term Fire Weather Variability for Russian Boreal Forest in the Republic of Sakha (Yakutia)

The Boreal forest is a terrestrial ecosystem highly vulnerable to the impacts of short-term climate and weather variabilities. Detecting abrupt, rapid climate-induced changes in fire weather and related changes in fire seasonality can provide important insights to assessing impacts of climate change on forestry. This paper, taking the Sakha Republic of Russia as study area, aims to suggest an approach for detecting signals indicating climate-induced changes in fire weather to express recent fire weather variability by using short-term ranks of major meteorological parameters such as air temperature and atmospheric precipitation. Climate data from the “Global Summary of the Day Product” of NOAA (the United States National Oceanic and Atmospheric Administration) for 1996 to 2018 were used to investigate meteorological parameters that drive fire activity. The detection of the climate change signals is made through a 4-step analysis. First, we used descriptive statistics to grasp monthly, annual, seasonal and peak fire period characteristics of fire weather. Then we computed historical normals for WMO reference period, 1961-1990, and the most recent 30-year period for comparison with the current means. The variability of fire weather is analyzed using standard deviation, coefficient of variation, percentage departures from historical normals, percentage departures from the mean, and precipitation concentration index. Inconsistency and abrupt changes in the evolution of fire weather are assessed using homogeneity analysis whilst a Mann-Kendall test is used to detect significant trends in the time series. The results indicate a significant increase of temperature during spring and fall months, which extends the fire season and potentially contributes to increase of burned areas. We again detected a significant rainfall shortage in September which extended the fire season. Furthermore, this study suggests a new approach in statistical methods appropriate for the detection of climate change signals on fire weather variability using short-term climate ranks and evaluation of its impact on fire seasonality and activity.

Automatic Extraction of Medical Latent Variables from ECG Signals Utilizing a Mutual Information-Based Technique and Capsular Neural Networks for Arrhythmia Detection

From a medical perspective,the 12 leads of the heart in an electrocardiogram(ECG)signal have functional dependencies with each other.Therefore,all these leads report different aspects of an arrhythmia.Their differences lie in the level of highlighting and displaying information about that arrhythmia.For example,although all leads show traces of atrial excitation,this function is more evident in lead II than in any other lead.In this article,a new model was proposed using ECG functional and structural dependencies between heart leads.In the prescreening stage,the ECG signals are segmented from the QRS point so that further analyzes can be performed on these segments in a more detailed manner.The mutual information indices were used to assess the relationship between leads.In order to calculate mutual information,the correlation between the 12 ECG leads has been calculated.The output of this step is a matrix containing all mutual information.Furthermore,to calculate the structural information of ECG signals,a capsule neural network was implemented to aid physicians in the automatic classification of cardiac arrhythmias.The architecture of this capsule neural network has been modified to perform the classification task.In the experimental results section,the proposed model was used to classify arrhythmias in ECG signals from the Chapman dataset.Numerical evaluations showed that this model has a precision of 97.02%,recall of 96.13%,F1-score of 96.57%and accuracy of 97.38%,indicating acceptable performance compared to other state-of-the-art methods.The proposed method shows an average accuracy of 2%superiority over similar works.

Emotion Measurement Using Biometric Signal

In recent years, research on the estimation of human emotions has been active, and its application is expected in various fields. Biological reactions, such as electroencephalography (EEG) and root mean square successive difference (RMSSD), are indicators that are less influenced by individual arbitrariness. The present study used EEG and RMSSD signals to assess the emotions aroused by emotion-stimulating images in order to investigate whether various emotions are associated with characteristic biometric signal fluctuations. The participants underwent EEG and RMSSD while viewing emotionally stimulating images and answering the questionnaires. The emotions aroused by emotionally stimulating images were assessed by measuring the EEG signals and RMSSD values to determine whether different emotions are associated with characteristic biometric signal variations. Real-time emotion analysis software was used to identify the evoked emotions by describing them in the Circumplex Model of Affect based on the EEG signals and RMSSD values. Emotions other than happiness did not follow the Circumplex Model of Affect in this study. However, ventral attentional activity may have increased the RMSSD value for disgust as the β/θ value increased in right-sided brain waves. Therefore, the right-sided brain wave results are necessary when measuring disgust. Happiness can be assessed easily using the Circumplex Model of Affect for positive scene analysis. Improving the current analysis methods may facilitate the investigation of face-to-face communication in the future using biometric signals.

A VIBRATION RECOGNITION METHOD BASED ON DEEP LEARNING AND SIGNAL PROCESSING

Effective vibration recognition can improve the performance of vibration control and structural damage detection and is in high demand for signal processing and advanced classification.Signal-processing methods can extract the potent time-frequency-domain characteristics of signals;however,the performance of conventional characteristics-based classification needs to be improved.Widely used deep learning algorithms(e.g.,convolutional neural networks(CNNs))can conduct classification by extracting high-dimensional data features,with outstanding performance.Hence,combining the advantages of signal processing and deep-learning algorithms can significantly enhance vibration recognition performance.A novel vibration recognition method based on signal processing and deep neural networks is proposed herein.First,environmental vibration signals are collected;then,signal processing is conducted to obtain the coefficient matrices of the time-frequency-domain characteristics using three typical algorithms:the wavelet transform,Hilbert-Huang transform,and Mel frequency cepstral coefficient extraction method.Subsequently,CNNs,long short-term memory(LSTM)networks,and combined deep CNN-LSTM networks are trained for vibration recognition,according to the time-frequencydomain characteristics.Finally,the performance of the trained deep neural networks is evaluated and validated.The results confirm the effectiveness of the proposed vibration recognition method combining signal preprocessing and deep learning.

Application of Holter ECG Signal Analysis Based on Wavelet and Data Mining Technique

A new model based on dyadic differential wavelet was developed for detecting the R peak in Holter ECG signal according to the design of data mining. The Mallat recursive filter algorithm was introduced to calculate wavelet and optimize the detection algorithm which is based on the equivalent filter technique. The detection algorithm has been verified by MIT arrhythmia database with a high efficiency of 99%. After optimization, the algorithm was put into clinical experiment and tested in the Air Force Hospital in Tianjin for about two months. After about 108 hearts beating test of more than 100 patients, the total efficient detection rate has reached 97%. Now this algorithm module has been applied in business software and shows perfect performance under the complex conditions such as the inversion of heart beating, the falling off of the electrodes, the excursion of base line and so on.

Detection of healthy and pathological heartbeat dynamics in ECG signals using multivariate recurrence networks with multiple scale factors

The electrocardiogram(ECG)is one of the physiological signals applied in medical clinics to determine health status.The physiological complexity of the cardiac system is related to age,disease,etc.For the investigation of the effects of age and cardiovascular disease on the cardiac system,we then construct multivariate recurrence networks with multiple scale factors from multivariate time series.We propose a new concept of cross-clustering coefficient entropy to construct a weighted network,and calculate the average weighted path length and the graph energy of the weighted network to quantitatively probe the topological properties.The obtained results suggest that these two network measures show distinct changes between different subjects.This is because,with aging or cardiovascular disease,a reduction in the conductivity or structural changes in the myocardium of the heart contributes to a reduction in the complexity of the cardiac system.Consequently,the complexity of the cardiac system is reduced.After that,the support vector machine(SVM)classifier is adopted to evaluate the performance of the proposed approach.Accuracy of 94.1%and 95.58%between healthy and myocardial infarction is achieved on two datasets.Therefore,this method can be adopted for the development of a noninvasive and low-cost clinical prognostic system to identify heart-related diseases and detect hidden state changes in the cardiac system.

Analysis and Process of Music Signals to Generate Two-Dimensional Tabular Data and a New Music

The processing of sound signals is significantly improved recently.Technique for sound signal processing focusing on music beyond speech area is getting attention due to the development of deep learning techniques.This study is for analysis and process of music signals to generate tow-dimensional tabular data and a new music.For analysis and process part,we represented normalized waveforms for each of input data via frequency domain signals.Then we looked into shorted segment to see the difference wave pattern for different singers.Fourier transform is applied to get spectrogram of the music signals.Filterbank is applied to represent the spectrogram based on the human ear instead of the distance on the frequency dimension,and the final spectrogram has been plotted by Mel scale.For generating part,we created two-dimensional tabular data for data manipulation.With the 2D data,any kind of analysis can be done since it has digit values for the music signals.Then,we generated a new music by applying LSTM toward the song audience preferred more.As the result,it has been proved that the created music showed the similar waveforms with the original music.This study made a step forward for music signal processing.If this study expands further,it can find the pattern that listeners like so music can be generated within favorite singer’s voice in the way that the listener prefers.

Automated Deep Learning Based Cardiovascular Disease Diagnosis Using ECG Signals

Automated biomedical signal processing becomes an essential process to determine the indicators of diseased states.At the same time,latest develop-ments of artificial intelligence(AI)techniques have the ability to manage and ana-lyzing massive amounts of biomedical datasets results in clinical decisions and real time applications.They can be employed for medical imaging;however,the 1D biomedical signal recognition process is still needing to be improved.Electrocardiogram(ECG)is one of the widely used 1-dimensional biomedical sig-nals,which is used to diagnose cardiovascular diseases.Computer assisted diag-nostic modelsfind it difficult to automatically classify the 1D ECG signals owing to time-varying dynamics and diverse profiles of ECG signals.To resolve these issues,this study designs automated deep learning based 1D biomedical ECG sig-nal recognition for cardiovascular disease diagnosis(DLECG-CVD)model.The DLECG-CVD model involves different stages of operations such as pre-proces-sing,feature extraction,hyperparameter tuning,and classification.At the initial stage,data pre-processing takes place to convert the ECG report to valuable data and transform it into a compatible format for further processing.In addition,deep belief network(DBN)model is applied to derive a set of feature vectors.Besides,improved swallow swarm optimization(ISSO)algorithm is used for the hyper-parameter tuning of the DBN model.Lastly,extreme gradient boosting(XGBoost)classifier is employed to allocate proper class labels to the test ECG signals.In order to verify the improved diagnostic performance of the DLECG-CVD model,a set of simulations is carried out on the benchmark PTB-XL dataset.A detailed comparative study highlighted the betterment of the DLECG-CVD model interms of accuracy,sensitivity,specificity,kappa,Mathew correlation coefficient,and Hamming loss.

Biomimetic Synthesized Conductive Copolymer EDOT-Pyrrole Electrodes for Electrocardiogram Recording in Humans

We report on electrodes fabricated with EDOT-Pyrrole copolymer through electrophoretic deposition and used for recording and sensing bio-electrical signals. We measured the electrical properties of the copolymer deposited on a stainless-steel substrate, and we performed Cyclic Voltammetry (CV) and Scanning Electron Microscopy (SEM) studies to characterize the morphological properties and copolymer distribution on the metal surface. We found that electrodes fabricated with EDOT-Pyrrole copolymer exhibit a high signal-to-noise ratio as well as an accurate and stable conductivity compared with other commonly used electroconductive polymers. Stainless-steel-coated EDOT-Pyrrole electrodes are suitable to record electrocardiograms in humans with high resolution comparable to standard silver-electrodes.

A Novel Radial Basis Function Neural Network Approach for ECG Signal Classification

ions in the ECG signal.The cardiologist and medical specialistfind numerous difficulties in the process of traditional approaches.The specified restrictions are eliminated in the proposed classifier.The fundamental aim of this work is tofind the R-R interval.To analyze the blockage,different approaches are implemented,which make the computation as facile with high accuracy.The information are recovered from the MIT-BIH dataset.The retrieved data contain normal and pathological ECG signals.To obtain a noiseless signal,Gaborfilter is employed and to compute the amplitude of the signal,DCT-DOST(Discrete cosine based Discrete orthogonal stock well transform)is implemented.The amplitude is computed to detect the cardiac abnormality.The R peak of the underlying ECG signal is noted and the segment length of the ECG cycle is identified.The Genetic algorithm(GA)retrieves the primary highlights and the classifier integrates the data with the chosen attributes to optimize the identification.In addition,the GA helps in performing hereditary calculations to reduce the problem of multi-target enhancement.Finally,the RBFNN(Radial basis function neural network)is applied,which diminishes the local minima present in the signal.It shows enhancement in characterizing the ordinary and anomalous ECG signals.

刺绣心电电极设计与性能分析

为提高刺绣心电电极的灵敏性和稳定性,规范电极设计与应用,分别对刺绣电极的面积、图案、针迹进行设计,并分析其影响要素。采用控制变量的实验方案,分析电极厚度、平整度、皮肤-电极界面阻抗、信噪比、基线稳定时间、基线偏移幅度的变化规律,找出刺绣电极物理特征和电学性能的影响因素。研究结果发现:刺绣电极面积过大或过小都会对其传感灵敏性和捕捉的信号质量造成负面影响;刺绣电极图案越接近圆形其各项性能均越好;成品厚度均匀、表面平整的针迹制备的刺绣电极传感稳定性和信号质量更好;经过优化设计得出的5.3 cm^(2)圆形缎纹针迹刺绣电极,与3M公司生产的2223CN医用电极相比,皮肤-电极界面阻抗降低了1.064 MΩ,信噪比提高了3.133 dB,基线稳定时间缩短了3 s,基线偏移幅度减小0.07 mV,具有良好的外观平整度、电学灵敏性及稳定性。

两步式自适应阈值法滤除心电信号中运动伪迹

心电信号广泛应用于心脏疾病的医学检测中,可穿戴动态心电监测设备可以实现对心律失常的风险识别并预警.相比于静息心电信号,动态心电信号在采集过程中会受到更大运动伪迹的干扰,这些干扰会覆盖心电信号的关键信息,限制其临床应用.本文兼顾心电信号局部和全局特征,利用其周期性,研究了一种将心电信号低频PT波和高频QRS波群分开处理的两步式自适应阈值滤波算法,适用于单通道心电信号中的运动伪迹滤除.第一步先通过多分辨率阈值初步抑制心电信号低频部分中的运动伪迹;第二步,对受运动伪迹影响而不平衡的QRS波进行自适应阈值修复,通过对QRS波形调节,减少心电信号中高频部分运动伪迹,同时设置自适应阈值对心电信号P波、T波对应的小波系数进行处理,超出自适应阈值范围的小波系数通过波形缩放进行调整,进一步抑制低频运动伪迹.研究通过不同心电数据库评估算法的性能.在输入信噪比从-10~10 dB时,心电信号信噪比提升了10.9122 dB和4.3912 dB,滤波后心电信号与纯净心电信号的相关系数分别为0.6876和0.9783,提取的运动伪迹与原运动伪迹相关系数分别为0.9530和0.8529.实验结果表明,算法在不同噪声水平下,利用自适应阈值的优点,能有效复原受运动伪迹污染的心电信号波形特征,最大限度保留心电信号的临床信息,可作为可穿戴心电设备滤除运动伪迹的有效工具.

基于LabVIEW的心电信号与多数据采集分析系统设计

近年来心血管疾病的发病率和死亡率不断攀升。为了给人们提供一个较为准确的心电信号分析结果,该系统以心电信号为感知节点,结合虚拟仪器技术,打造一个准确性更高、成本更低、更可靠的心电信号分析系统。它的优点在于会结合使用者的各种因素,如:所处气象、饮食、地理位置、身体状况和生活习惯等因素,并结合已经发展较为成熟的心电信号数据分析手段,在对连续的心电图数据实时采集处理与分析功能方面,此设备具有数据实时性、精度较高等特点。结果表明,结合了多数据的分析结果,比单一分析系统给出的结果更为准确,也更加能够满足人们的需要,这将对预防和治疗心血管疾病产生重要作用。

一种融合KPCA、FastICA及SVD的腹壁源胎儿心电 信号提取算法研究

目的:为实现从母体腹壁混合信号中提取高信噪比和波形清晰的胎儿心电信号,提出一种融合核主成分分析(kernel principal component analysis,KPCA)、快速独立成分分析(fast independent component analysis,FastICA)及奇异值分解(singular value decomposition,SVD)的胎儿心电信号提取算法。方法:首先,采用KPCA对母体心电信号进行降维,再利用改进的基于负熵的FastICA处理降维后的数据,得到独立成分。随后,引入样本熵进行信号通道选择,挑选出包含最多母体信息的信号通道。在选中的母体通道上进行SVD,得到母体心电信号的近似估计,再用腹壁源信号减去该信号得到胎儿心电的初步估计。最后,采用改进的基于负熵的FastICA成功分离出纯净的胎儿心电信号。在腹部和直接胎儿心电图数据库(Abdominal and Direct Fetal Electrocardiogram Database,ADFECGDB)和PhysioNet 2013挑战赛数据库中对提出的算法进行验证。结果:提出的算法在主观视觉效果和客观评价指标上都表现出优越的性能。在ADFECGDB数据库中,胎儿QRS复合波检测的敏感度、阳性预测值和F1值分别为99.74%、98.85%和99.30%;在PhysioNet 2013挑战赛数据库中,胎儿QRS复合波检测的敏感度、阳性预测值和F1值分别为99.10%、97.87%和98.48%。结论:融合KPCA、FastICA及SVD的胎儿心电信号提取算法在提取胎儿心电信号的同时有效处理了附加噪声,为胎儿疾病的早期诊断提供了有力支持。

胎儿心电图的应用与进展

对胎儿心电图(fetal electrocardiogram,FECG)进行简单介绍,阐述近年来FECG技术在检测胎儿心律失常、监测妊娠高血压综合征患者宫内胎儿缺氧状况等方面的临床应用,并梳理了FECG本身存在的局限性。本文还总结了FECG信号处理技术的进展,并展望FECG未来的发展前景。

基于特征融合的多通道心肌梗死定位模型

心肌梗死(MI)是心血管疾病(CVD)中常见的临床表现形式,在发病时具有较高的致命性,因此心肌梗死的快速定位对于避免死亡至关重要。目前基于心电图的心肌梗死位置定位模型在面对患者间的个体差异时泛化性能不足,同时传统的基于卷积的模型难以深入挖掘心电图导联与心肌梗死位置之间的关系。为解决这些问题,提出一种基于特征融合的多通道心肌梗死定位模型FF-ANN,该模型主要由特征融合模块和自适应的多通道注意力模块组成。通过特征融合模块整合临床知识中的关键波型特征(例如Q波、ST段等),使模型具有多种感受域,从而在不同维度上捕捉心肌梗死的特征;利用自适应的多通道注意力模块对融合后的特征进行重新标定,通过注意力权重加权对应的特征,使模型聚焦对预测有重要贡献的导联特征。通过在混合数据集PTB上验证模型的拟合能力,并使用迁移学习的方法将从PTB数据集中学习到的模型架构迁移到PTBXL数据集中进行泛化能力验证,结果表明,与现有研究相比,该模型在患者间方案下实现了约2.5%的提升,证明了该模型不仅具有较好的定位性能,也显示优越的泛化能力,其架构适用于现实世界中辅助心肌梗死定位的诊断。

基于遗传算法优化最小二乘支持向量机的矿工疲劳程度识别模型

为精准识别矿工疲劳程度,减少因疲劳引发的煤矿人因事故,提出了一种基于遗传算法(GA)优化最小二乘支持向量机(LSSVM)的矿工疲劳程度识别模型。首先,通过疲劳诱发试验采集矿工心电数据,利用Friedman检验优选矿工疲劳程度的特征指标;然后,采用主成分分析法对选取的特征指标进行降维处理,建立表征矿工疲劳程度的特征集;在此基础上,利用遗传算法优化最小二乘支持向量机的关键参数,构建矿工疲劳程度识别模型。结果表明:选取的矿工疲劳程度特征指标能够有效反映矿工的疲劳程度;相较GA-SVM和LSSVM模型,融合GA-LSSVM模型可显著提高矿工疲劳程度的识别准确率(平均识别准确率为96.87%)。构建的矿工疲劳程度识别模型可较为高效地识别矿工的疲劳程度,对煤矿人因事故的防控具有一定的现实指导意义。

基于优化自适应模型的心律失常辅助诊断方法

针对心律失常诊断算法中存在的不平衡数据集诊断准确率及阳性预测值较低的问题,提出一种基于优化自适应模型的心律失常辅助诊断方法;提取心电信号的77维特征并将其融合,使用融合特征训练诊断模型,同时利用改进的粒子群算法优化自适应模型参数;采用优化模型对MIT-BIH心律失常数据库进行诊断实验并与现有方法进行对比。结果表明,本文所提方法在测试数据集的诊断准确率达到98.2%,正常或束支传导阻滞节拍、室上性异常节拍、心室异常节拍、融合节拍的阳性预测值分别达到98.5%、96.1%、95.5%、92.0%,诊断准确率和阳性预测值明显大于现有方法的。