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121.
Nonlinear time series and principal component analyses: Potential diagnostic tools for COVID-19 auscultation
Mohanachandran Nair Sindhu Swapna, RAJ VIMAL, RENJINI A, SREEJYOTHI S, SANKARARMAN S, 2020, izvirni znanstveni članek

Opis: The development of novel digital auscultation techniques has become highly significant in the context of the outburst of the pandemic COVID 19. The present work reports the spectral, nonlinear time series, fractal, and complexity analysis of vesicular (VB) and bronchial (BB) breath signals. The analysis is carried out with 37 breath sound signals. The spectral analysis brings out the signatures of VB and BB through the power spectral density plot and wavelet scalogram. The dynamics of airflow through the respiratory tract during VB and BB are investigated using the nonlinear time series and complexity analyses in terms of the phase portrait, fractal dimension, Hurst exponent, and sample entropy. The higher degree of chaoticity in BB relative to VB is unwrapped through the maximal Lyapunov exponent. The principal component analysis helps in classifying VB and BB sound signals through the feature extraction from the power spectral density data. The method proposed in the present work is simple, cost-effective, and sensitive, with a far-reaching potential of addressing and diagnosing the current issue of COVID 19 through lung auscultation.
Ključne besede: Breath sound analysis, Fractal dimension, Nonlinear time series analysis, Sample entropy, Hurst exponent, Principal component analysis
Objavljeno v RUNG: 28.06.2022; Ogledov: 1853; Prenosov: 0
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122.
Unravelling the potential of phase portrait in the auscultation of mitral valve dysfunction
Mohanachandran Nair Sindhu Swapna, SREEJYOTHI S, RENJINI A, RAJ VIMAL, SANKARARAMAN SANKARANARAYANA IYER, 2021, izvirni znanstveni članek

Opis: The manuscript elucidates the potential of phase portrait, fast Fourier transform, wavelet, and time-series analyses of the heart murmur (HM) of normal (healthy) and mitral regurgitation (MR) in the diagnosis of valve-related cardiovascular diseases. The temporal evolution study of phase portrait and the entropy analyses of HM unveil the valve dysfunctioninduced haemodynamics. A tenfold increase in sample entropy in MR from that of normal indicates the valve dysfunction. The occurrence of a large number of frequency components between lub and dub in MR, compared to the normal, is substantiated through the spectral analyses. The machine learning techniques, K-nearest neighbour, support vector machine, and principal component analyses give 100% predictive accuracy. Thus, the study suggests a surrogate method of auscultation of HM that can be employed cost-effectively in rural health centres.
Ključne besede: phase portrait, auscultation, mitral valve dysfunction, heart murmur, nonlinear time series analysis
Objavljeno v RUNG: 28.06.2022; Ogledov: 1476; Prenosov: 0
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123.
Development of prototype of electronic speckle interferometry based spirometer
Mohanachandran Nair Sindhu Swapna, KUMAR ARUN, KUMAR SUNIL, SREEJYOTHI S, RAJ VIMAL, SANKARARAMAN SANKARANARAYANA IYER, 2021, izvirni znanstveni članek

Opis: The paper reports the design, construction, and calibration of the prototype of a spirometer based on electronic speckle interferometry (ESPI). The conventional ESPI setup is modified by incorporating a DNM (Diaphragm-Nozzle-Mouthpiece) module comprising a metallic diaphragm, regulated airflow channel, and a mouthpiece. The exhaled air after a deep breathe is channelled to the DNM module where the diaphragm gets deformed. From the circular fringe pattern obtained by subtracting the speckled images before and after deformation of the metallic diaphragm, the radius of curvature (R) due to deformation is calculated using the principle of Newton’s rings. The value of R and peak expiratory flow rate (PEFR) from the standard spirometer reading are correlated. From the 640 observations spread over the range 100 - 500 L/min in the standard spirometer, an empirical relation is set in terms of R from the scatter plot. The ESPI spirometer (ESPIS) is validated by determining the value of R corresponding to a particular PEFR from the empirical relation and also from the standard spirometer. The PEFR calculated from ESPIS matches well with the standard spirometer reading, which suggests that the system designed and constructed can be used for biomedical applications for assessing lungs’ efficiency.
Ključne besede: Speckle, Spirometer, DNM module, ESPIS, Peak expiratory flow rate
Objavljeno v RUNG: 28.06.2022; Ogledov: 1464; Prenosov: 0
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124.
Thermal Lensing of Multi-Walled Carbon Nanotube Solutions as Heat-Transfer Nanofluids
Mohanachandran Nair Sindhu Swapna, RAJ VIMAL, CABRERA HUMBERTO, SANKARARAMAN SANKARANARAYANA IYER, 2021, izvirni znanstveni članek

Opis: This paper unwraps nanofluids’ particle dynamics with multi-walled carbon nanotubes (MWCNTs) in base fluids such as acetone, water, and ethylene glycol. Having confirmed the morphology and structure of the MWCNTs by field emission scanning electron microscopy, X-ray diffraction, and Raman spectroscopic analyses, the nanofluids are prepared in three different concentrations. The nonzero absorbance at the laser wavelength, revealed through the UV−visible spectrum, makes the thermal diffusivity study of the sample by the sensitive nondestructive single beam thermal lens (TL) technique possible. The TL signal analysis by time series and fractal techniques divulges the complex particle dynamics, through phase portrait, sample entropy, fractal dimension, and Hurst exponent. The study unveils the effect of the amount of nanoparticles and the viscosity of the medium on thermal diffusivity and particle dynamics. The observed inverse relation between thermal diffusivity and viscosity is in good agreement with the Sankar−Swapna model. The complexity of particle dynamics in MWCNT nanofluids reflected through sample entropy, and fractal dimension shows an inverse relation to the base fluid’s viscosity. This paper investigates the role of viscosity of the base fluid on particle dynamics and thermal diffusivity of the nanofluid to explore its applicability in various thermal systems, thereby suggesting a method to tune the sample entropy through proper selection of base fluid.
Ključne besede: MWCNT, thermal lens, fractals, nonlinear time series, phase portrait, sample entropy
Objavljeno v RUNG: 28.06.2022; Ogledov: 1731; Prenosov: 0
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