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1

Early detection of sudden cardiac death using nonlinear analysis of heart rate variability

Khazaei M., Raeisi K., Goshvarpour A., Ahmadzadeh M.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 4

931--940

EN

Background and objective: Sudden cardiac death (SCD) is one of the most widespread reasons for death around the world. A precise and early prediction of SCD can improve the chance of survival by administering cardiopulmonary resuscitation (CPR). Hence, there is a vital need for an SCD prediction system. Methods: In this work, a novel and efficient algorithm for automated detection of SCD six minutes before its onset is proposed. This algorithm uses features based on the nonlinear modeling of heart rate variability (HRV). In fact, after the extraction of the HRV signals, increment entropy and recurrence quantification analysis-based features are extracted. The one-way ANOVA is applied for the dimension reduction of feature space—this results in lower computational cost. Finally, the distinguishing features are fed to classifiers such as the decision tree, K-nearest neighbor, naive Bayes, and the support vector machine. Results: By using the decision tree classifier we have achieved SCD detection six minutes before its onset with an accuracy, specificity, and sensitivity of 95%. These results demonstrate the superiority of the presented algorithm compared to the existing ones in performance. Conclusions: This study shows that a combination of features based on the nonlinear modeling of HRV, such as laminarity (based on recurrence quantification analysis), and increment entropy leads to early detection of SCD. Choosing the decision tree improves the performance of the algorithm. The results could help in the development of a tool that would allow the detection of cardiac arrest six minutes before its onset.

2

Analysis of heart rate variability as a predictor of mortality in cardiovascular patients of intensive care unit

Moridani M. K., Setarehdan S. K., Nasrabadi A. M., Hajinasrollah E.

Biocybernetics and Biomedical Engineering

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2015

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Vol. 35, no. 4

217--226

EN

Objective: Dynamic changes of heart rate variability (HRV) reflect autonomic dysfunction in cardiac disease. Some studies suggest the role of HRV in predicting intensive care unit (ICU) mortality. The main object of this study was analyzing the HRV to design an algorithm to predict mortality risk. Methods: We evaluated 80 cardiovascular ICU patients (45 males and 45 females), ranging from 45 to 70 years. Common time and frequency domain analysis, non-linear Poincaré plot and recurrence quantification analysis (RQA) were used to study the HRV in two episodes. The episodes include 8–4 h before death, and 4 h before death to death. Independent sample t-test was used as statistical analysis. Results: Statistical analysis indicates that frequency domain and Poincaré parameters such as LF/HF and SD2/SD1 show changes in transition to death episode (p < 0.05). Moreover, Lmean, vmax and RT measures showed meaningful changes (p < 0.01) in closer segments to the death. Conclusions: Analysis of physiological variables shows that there are significant differences in RQA measures in episodes close to death. These changes can be interpreted as more stability and determinism behavior of HRV in episodes close to death. RQA parameters can be used together with HRV parameters for description and prediction of mortality risk in ICU patients.

3

Detection of two-phase flow patterns in a vertical minichannel using the recurrence quantification analysis

Mosdorf R., Górski G.

Acta Mechanica et Automatica

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2015

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Vol. 9, no. 2

99--104

EN

The two-phase flow (water-air) occurring in square minichannel (3x3 mm) has been analysed. In the minichannel it has been observed: bubbly flow, flow of confined bubbles, flow of elongated bubbles, slug flow and semi-annular flow. The time series recorded by laser-phototransistor sensor was analysed using the recurrence quantification analysis. The two coefficients:Recurrence rate (RR) and Determinism (DET) have been used for identification of differences between the dynamics of two-phase flow patterns. The algorithm which has been used normalizes the analysed time series before calculating the recurrence plots.Therefore in analysis the quantitative signal characteristicswas neglected. Despite of the neglect of quantitative signal characteristics the analysis of its dynamics (chart of DET vs. RR) allows to identify the two-phase flow patterns. This confirms that this type of analysis can be used to identify the two-phase flow patterns in minichannels.

4

Rekonstrukcja atraktora Monarchy Safye na podstawie szeregów czasowych

Wysocki H.

Zeszyty Naukowe Akademii Marynarki Wojennej

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2012

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R. 53 nr 1 (188)

149-172

PL

W artykule opisano zagadnienie rekonstrukcji atraktora na podstawie szeregu czasowego oraz przedstawiono oprogramowanie pozwalające wyznaczać jej parametry. Zagadnienie to zastosowano do rekonstrukcji atraktora Monarchy Safye na podstawie szeregów czasowych otrzymanych z numerycznego rozwiązania układu dynamicznego opisującego ten atraktor. Wskazano również na związek rekonstrukcji atraktora z analizą rekurencyjną szeregu czasowego.

EN

The paper describes the problem of attractor reconstruction on the basis of a time series and presents software allowing to specify the reconstruction parameters. The above problem has been applied to reconstruct the Monarch Safye attractor on the basis of time series obtained from a numerical solution of a dynamic system describing that attractor. It has also been indicated that there exists a relation between the attractor reconstruction and the recurrence analysis of a time series.

5

Dynamics of composite materials cutting

Rusinek R., Kecik K., Warminski J.

Advances in Manufacturing Science and Technology

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2011

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Vol. 35, nr 3

31-37

EN

The paper presents stability analysis of milling process of epoxide polymer composite material with carbon fibres. In order to determine zones of stable milling, times series of cutting forces are applied. Next, recurrence quantification analysis is conducted which can define three stability indexes: recurrence rate, ratio of recurrence rate to determinism, and recurrence time. Finally, stability lobs diagram for the composite material is proposed.

PL

W pracy zaprezentowano wyniki badania stabilności procesu frezowania kompozytu epoksydowo-polimerowego wzmacnianego włóknem węglowym. Określono obszary skrawania stabilnego. Prowadzono analizę przebiegów czasowych sił skrawania opartą na kwantyfikatorach wykresów rekurencyjnych. Stosowano trzy z nich: recurrence rate, proporcję recurrence rate i determinizmu oraz czas rekurencji. Opracowano wykres stabilności frezowania materiału kompozytowego.