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Nondestructive Evaluation of Surface Roughness of Thin Films through Fractal Analysis, S Soumya
Mohanachandran Nair Sindhu Swapna, 2017, original scientific article

Keywords: Nondestructive Evaluation, Surface Roughness, Thin Films, Fractal Analysis
Published in RUNG: 05.07.2022; Views: 1447; Downloads: 0
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Time series analysis of duty cycle induced randomness in thermal lens system
Mohanachandran Nair Sindhu Swapna, 2020, original scientific article

Abstract: The present work employs time series analysis, a proven powerful mathematical tool, for investigating the complex molecular dynamics of the thermal lens (TL) system induced by the duty cycle (C) variation. For intensity modulation, TL spectroscopy commonly uses optical choppers. The TL formation involves complex molecular dynamics that vary with the input photothermal energy, which is implemented by varying the duty cycle of the chopper. The molecular dynamics is studied from the fractal dimension (D), phase portrait, sample entropy (S), and Hurst exponent (H) for different duty cycles. The increasing value of C is found to increase D and S, indicating that the system is becoming complex and less deterministic, as evidenced by the phase portrait analysis. The value of H less than 0.5 conforms the evolution of the TL system to more anti-persistent nature with C. The increasing value of C increases the enthalpy of the system that appears as an increase in full width at half maximum of the refractive index profile. Thus the study establishes that the sample entropy and thermodynamic entropy are directly related.
Keywords: Time series analysis Fractal analysis Photothermal lens spectroscopy Fractal dimension Hurst exponent Sample entropy
Published in RUNG: 05.07.2022; Views: 1516; Downloads: 0
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6.
Hidden periodicity in Stripe 82 with Saraswati supercluster—a fractal analysis
Vimal Raj, Mohanachandran Nair Sindhu Swapna, Sankaranarayana Iyer Sankararaman, 2021, original scientific article

Abstract: The manuscript attempts to explore the periodicity in the distribution of galaxies in the recently reported Saraswati supercluster and the Stripe 82 region containing it as an example. The report of 120 Mpc periodicity in the Abell galaxy clusters by power spectrum analysis is the motivation behind the study. The power spectral analysis across the central part of the Stripe 82 region shows a periodic variation of 3.09° or 71 Mpc in fractal dimension whereas an average angular periodicity of 3.45° or 94 Mpc is observed across the Stripe 82 region. This refers to the periodicity of complexity or cluster density of galaxy distribution. The texture of the distribution pattern understood through lacunarity analysis indicates a near symmetric distribution. Fractal dimensions like box-counting dimension, information dimension and correlation dimension are also found through multifractal analysis. While the information dimension tells about the distribution density of galactic points, the correlation dimension details the distribution of galaxies in the neighbourhood
Keywords: galaxy distribution, fractal analysis, multifractals, lacunarity, Saraswati supercluster, Stripe 82
Published in RUNG: 04.07.2022; Views: 1464; Downloads: 0
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Neural net pattern recognition based auscultation of croup cough and pertussis using phase portrait features
Mohanachandran Nair Sindhu Swapna, 2021, original scientific article

Abstract: Cough signal analysis for understanding the pathological condition has become important from the outset of the exigency posed by the epidemic COVID-19. The present work suggests a surrogate approach for the classification of cough signals - croup cough (CC) and pertussis (PT) – based on spectral, fractal, and nonlinear time-series techniques. The spectral analysis of CC reveals the presence of more frequency components in the short duration cough sound compared to PT. The musical nature of CC is unveiled not only through the spectral analysis but also through the phase portrait features – sample entropy (S), maximal Lyapunov exponent (L), and Hurst exponent (Hb). The modifications in the internal morphology of the respiratory tract, giving rise to more frequency components associated with the complex airflow dynamics, get staged through the higher fractal dimension of CC. Among the two supervised classification tools, cubic KNN (CKNN) and neural net pattern recognition (NNPR), used for classifying the CC and PT signals based on nonlinear time series parameters, NNPR is found better. Thus, the study opens the possibility of identification of pulmonary pathological conditions through cough sound signal analysis.
Keywords: Croup cough Pertussis Fractal dimension Phase portrait Sample entropy Machine learning techniques
Published in RUNG: 04.07.2022; Views: 1327; Downloads: 0
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9.
Evolution of fractal dimension in pulsed laser deposited MoO3 film with ablation time and annealing temperature
Mohanachandran Nair Sindhu Swapna, 2021, original scientific article

Abstract: The multifractal analysis is a potential method for assessing thin flm surface morphology and its changes due to diferent deposition conditions and post-deposition treatments. In this work, the multifractal analysis is carried out to understand the surface morphology—root mean square (RMS) surface roughness—of nanostructured MoO3 flms prepared by pulsed laser deposition technique by varying the ablation time and post-deposition annealing. The XRD analysis shows the evolution of crystalline nature with annealing temperature. The XRD pattern of all the annealed flms shows the characteristic peak of the orthorhombic MoO3 phase. The FESEM and AFM analysis reveals the morphological modifcation with ablation time and annealing temperature. The multifractal analysis of the AFM images shows that the box—counting, information and correlation dimension varies with the annealing temperature. The study also reveals the inverse relation between the fractal dimension and the RMS surface roughness due to the annealing induced particle size variation and reorientation. The fractal dimension’s evolution in the pulsed laser deposited MoO3 flm with ablation time and annealing temperature is also investigated. Thus, the study reveals the potential of multifractal analysis in the thin flm surface characterizatio
Keywords: Multifractal analysis · Pulsed laser deposition · Molybdenum oxide · Atomic force microscopy · Fractal dimension
Published in RUNG: 04.07.2022; Views: 1521; Downloads: 0
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10.
Investigation of Fractality and variation of fractal dimension in germinating seed
Mohanachandran Nair Sindhu Swapna, SREEJYOTHI S, Sankararaman S, 2020, original scientific article

Abstract: The fractal analysis has now been recognized as a potential mathematical tool in analyzing complex structures. The present work reports not only the fractal nature of Vigna radiata seed analyzed with the help of Field Emission Scanning Electron Microscopic images but also the variation of fractal dimension (FD) in a germinating seed. The variation of FD during germination in different media—water, salt, and diesel soot with carbon nanoparticles (CNPs)—is studied using the box-counting technique. The study is the first report of the fractality of seed. Irrespective of the media, the FD attains a maximum value on the day of germination and decreases after that. The time (T) for achieving maximum FD varies with the nature of stress. In the study, when the CNPs of diesel soot lower the T value, the salt raises the T value with respect to the control set. The Fourier Transform Infrared analysis of the seeds germinating in different media shows an increased rate of protein formation during the initial stage of germination and a steady state after that. In conjunction with the literature, the variation in the amino nitrogen, soluble nucleotide—RNA, and protein content of the seed during the initial days of germination gets reflected in its FD.
Keywords: fractal analysis, seed germination, Vigna radiata
Published in RUNG: 04.07.2022; Views: 1451; Downloads: 0
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