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Fractal and fingerprint analysis through phase embedded diffraction pattern
Swapna Mohanachandran Nair Sindhu, 2017, izvirni znanstveni članek

Opis: Fingerprint recognition is the most popular biometric identification method currently employed in security applications. Though there are several optical methods for fingerprint analysis based on intensity recording, phase recording alone can give the precise result. Interference and diffraction phenomenon are capable of recording phase variations. In the present method diffraction patterns corresponding to the fingerprints are generated and the spacing between the ridges is calculated. The spacing between ridges is found to be in agreement with the value measured using the software ImageJ. The fingerprint impressions of more than thirty-five persons are recorded and analyzed using the statistical tools in Matlab.The fingerprints are also subjected to fractal analysis. The program could successfully identify a fingerprint from the database. The present work is the first report of fingerprint analysis from diffraction pattern
Najdeno v: osebi
Ključne besede: Diffraction, Skew, Kurtosis, Fractals
Objavljeno: 30.06.2022; Ogledov: 485; Prenosov: 0
.pdf Polno besedilo (1020,06 KB)

Carbon Nanonecklaces with Carbon Nanotubes and Carbon Dots
Sankararaman S, Swapna Mohanachandran Nair Sindhu, 2017, izvirni znanstveni članek

Opis: Carbon nanoparticles (CNP) have gained significant attention representing unique carbon-based nanomaterials that find applications in various fields of science and technology. Carbon nanotubes (CNTs) and carbon dots (CDs) have now been widely employed as an electrode in super capacitors, as fluorescent nanomaterials for imaging and for fuel cell applications. In the present work, we describe a simple, low cost and chemical free method of synthesizing stable CNPs aligned in the form of a chain popularly known as carbon necklace with CNTs and CDs. Carbon nanoparticles are synthesized by controlled combustion of camphor in a single step flame process. The CNPs synthesized are characterized using X-ray Powder diffraction (XRD), Raman Spectroscopy, Energy Dispersive X ray diffraction (EDX), Fourier Transform Infrared Spectroscopy (FTIR), UV-Visible absorption and Photoluminescent (PL) Spectroscopy. The morphology and size of the CNPs are examined using Field Emission Scanning Electron Microscope (FESEM) which shows ‘necklace’ structure. The CNPs are collected at two different heights and the particles formed are found in the range 30 to 60 nm. The UV- Visible and PL Spectra of the CNPs obtained show the presence CDs. The Raman Spectroscopic and XRD analysis indicate the presence of CNTs in the sample.
Najdeno v: osebi
Ključne besede: Carbon nanoparticles, Combustion, Carbon nanotubes, Carbon dots, Carbon necklaces
Objavljeno: 30.06.2022; Ogledov: 462; Prenosov: 0
.pdf Polno besedilo (521,95 KB)

Investigation of graphene oxide in diesel soot
Swapna Mohanachandran Nair Sindhu, Sankararaman S, 2017, izvirni znanstveni članek

Opis: Graphene has emerged as a potential material in various scientific disciplines, ranging from material science, engineering, and more recently biomedicine. The paper describes the investigation of the presence of graphene and graphene oxide (GO) in the carbon soot of internal combustion diesel engines. The UV-Visible, Fourier transform infrared (FTIR), X- ray diffraction (XRD), Photoluminescent (PL) and Raman spectroscopic analysis of the sample provided a conclusive evidence of the formation of graphene and GO. The Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectrum (EDX) of the sample show carbon nanoparticles (CNPs) of size less than 50nm. The High -Resolution Transmission Electron Microscopy (HR-TEM) analysis confirmed the formation of graphene sheets with carbon nanospheres attached to it. The study reveals the possible exploitation of the diesel soot for potential applications in science and technology
Najdeno v: osebi
Ključne besede: Graphene, Graphene oxide, Carbon nanoparticles, Combustion, Carbon nanotube
Objavljeno: 30.06.2022; Ogledov: 506; Prenosov: 0
.pdf Polno besedilo (1,27 MB)

Synthesis and Characterization of Carbon Nano Kajal
Swapna Mohanachandran Nair Sindhu, 2017, kratki znanstveni prispevek

Opis: Carbon nanoparticles are of considerable interest today because of their unique physical and biological properties. There are several methods of preparation of Carbon Nanoparticles (CNP) with high efficacy and low toxicity. In this paper we describe a simple low cost synthesis of carbon nanoparticle. We present a simple method for the synthesis of carbon nanoparticles from the controlled combustion of coconut oil and ghee. The antibacterial property of CNP enables its use in kajals. The FESEM image of the sample prepared exhibit carbon nanoparticles of size less than 50nm
Najdeno v: osebi
Ključne besede: Kajal, carbon nanoparticles, soot
Objavljeno: 30.06.2022; Ogledov: 444; Prenosov: 0
.pdf Polno besedilo (526,57 KB)

Complex network-based cough signal analysis for digital auscultation: a machine learning approach
Swapna Mohanachandran Nair Sindhu, 2022, izvirni znanstveni članek

Opis: The paper proposes a novel approach to bring out the potential of complex networks based on graph theory to unwrap the hidden characteristics of cough signals, croup (BC), and pertussis (PS). The spectral and complex network analyses of 48 cough sounds are utilized for understanding the airflow through the infected respiratory tract. Among the different phases of the cough sound time-domain signals of BC and PS – expulsive (X), intermediate (I), and voiced (V) - the phase ‘I’ is noisy in BC due to improper glottal functioning. The spectral analyses reveal high-frequency components in both cough signals with an additional high-intense low-frequency spread in BC. The complex network features created by the correlation mapping approach, like number of edges (E), graph density (G), transitivity (), degree centrality (D), average path length (L), and number of components () distinguishes BC and PS. The higher values of E, G, and for BC indicate its musical nature through the strong correlation between the signal segments and the presence of high-intense low-frequency components in BC, unlike that in PS. The values of D, L, and discriminate BC and PS in terms of the strength of the correlation between the nodes within them. The linear discriminant analysis (LDA) and quadratic support vector machine (QSVM) classifies BC and PS, with greater accuracy of 94.11% for LDA. The proposed work opens up the potentiality of employing complex networks for cough sound analysis, which is vital in the current scenario of COVID-19.
Najdeno v: osebi
Ključne besede: Complex network analysis, Auscultation, Croup cough, Pertussis Spectral analysis, Machine learning techniques
Objavljeno: 30.06.2022; Ogledov: 584; Prenosov: 0
.pdf Polno besedilo (1,71 MB)

Bioacoustic signal analysis through complex network features
Sankararaman S, RAJ VIMAL, Swapna Mohanachandran Nair Sindhu, 2022, izvirni znanstveni članek

Opis: The paper proposes a graph-theoretical approach to auscultation, bringing out the potential of graph features in classifying the bioacoustics signals. The complex network analysis of the bioacoustics signals - vesicular (VE) and bronchial (BR) breath sound - of 48 healthy persons are carried out for understanding the airflow dynamics during respiration. The VE and BR are classified by the machine learning techniques extracting the graph features – the number of edges (E), graph density (D), transitivity (T), degree centrality (Dcg) and eigenvector centrality (Ecg). The higher value of E, D, and T in BR indicates the temporally correlated airflow through the wider tracheobronchial tract resulting in sustained high-intense low-frequencies. The frequency spread and high-frequencies in VE, arising due to the less correlated airflow through the narrow segmental bronchi and lobar, appears as a lower value for E, D, and T. The lower values of Dcg and Ecg justify the inferences from the spectral and other graph parameters. The study proposes a methodology in remote auscultation that can be employed in the current scenario of COVID-19.
Najdeno v: osebi
Ključne besede: Bioacoustic signal, Graph theory, Complex network, Lung auscultation
Objavljeno: 30.06.2022; Ogledov: 477; Prenosov: 0
.pdf Polno besedilo (2,63 MB)

Fractal and inertia moment analyses for thin film quality monitoring
Swapna Mohanachandran Nair Sindhu, 2022, izvirni znanstveni članek

Opis: The widespread applications of thin films in optronics demand innovative techniques for its characterizations. The work reported here proposes electronic speckle pattern interferometry and fractal-based methods for assessing the quality of thin films taking the industrially relevant molybdenum oxide (MoO3) incorporated niobium oxide (Nb2O5) films. The films with different levels of MoO3 incorporation (1, 2, 3, 5, and 10 wt. %) are prepared by radio frequency sputtering. The study reveals the structure modifications of Nb2O5 from the orthorhombic to monoclinic phases with an associated morphological variation revealed through atomic force microscopy and field-emission scanning electron microscopy analyses. The films’ specklegrams are recorded under thermal stress; the inertia moment (IM) and fractal analyses are computed and compared with the root-mean-square surface roughness of the films. The lacunarity analysis of the AFM films agrees well with the specklegrams. Thus, the lower IM and lacunarity values of the specklegrams can be regarded as indicators of the good quality of thin films.
Najdeno v: osebi
Ključne besede: cross-correlation, fractal dimension, inertia moment, lacunarity, speckle, surface roughness.
Objavljeno: 30.06.2022; Ogledov: 491; Prenosov: 0
.pdf Polno besedilo (2,33 MB)

RF sputtered boron carbide thin film for UVB and UVC shielding: A greener approach
Swapna Mohanachandran Nair Sindhu, 2022, izvirni znanstveni članek

Opis: The paper reports the development of RF sputtered boron carbide coatings as refractory and UV-shielder for high-temperature goggles and spacecraft applications. The advancement in the design and fabrication of machinery and UV optics necessitates the development of low-cost, eco-friendly preparation of wear-resistant refractory coatings with strong absorption in the UV region. Boron carbide coatings have proven their potential as abrasives besides their electronic applications. In the present work, boron carbide coatings are prepared by RF sputtering technique using the target prepared by low-temperature hydrothermal synthesis using cotton as carbon precursor. The sample synthesized and the film prepared are subjected to structure, morphological, and optical characterizations. The X-ray diffraction, Fourier transform infrared, micro-Raman and X-ray photoelectron studies confirm the formation of boron-rich boron carbide with the thermal stability of 87% at 800 C, revealed through the thermogravimetric analysis. The Tauc plot analysis gives the bandgap energy of the boron carbide target and film as 2.66 eV and 2.70 eV, respectively. The UV–Vis spectroscopic study also reveals the potential of the sample and the film in blocking UVB and UVC. The CIE plot from the photoluminescence study suggests the sample to be a blue light emitter.
Najdeno v: osebi
Ključne besede: Boron carbide, RF sputtering, uv shielding, thin films
Objavljeno: 30.06.2022; Ogledov: 430; Prenosov: 0
.pdf Polno besedilo (1,78 MB)

Graph based feature extraction and classification of wet and dry cough signals: A machine learning approach
Swapna Mohanachandran Nair Sindhu, 2021, izvirni znanstveni članek

Opis: This article proposes a unique approach to bring out the potential of graph-based features to reveal the hidden signatures of wet (WE) and dry (DE) cough signals, which are the suggestive symptoms of various respiratory ailments like COVID 19. The spectral and complex network analyses of 115 cough signals are employed for perceiving the airflow dynamics through the infected respiratory tract while coughing. The different phases of WE and DE are observed from their time-domain signals, indicating the operation of the glottis. The wavelet analysis of WE shows a frequency spread due to the turbulence in the respiratory tract. The complex network features namely degree centrality, eigenvector centrality, transitivity, graph density and graph entropy not only distinguish WE and DE but also reveal the associated airflow dynamics. A better distinguishability between WE and DE is obtained through the supervised machine learning techniques (MLTs)—quadratic support vector machine and neural net pattern recognition (NN), when compared to the unsupervised MLT, principal component analysis. The 93.90% classification accuracy with a precision of 97.00% suggests NN as a better classifier using complex network features. The study opens up the possibility of complex network analysis in remote auscultation.
Najdeno v: osebi
Ključne besede: wet cough, dry cough, complex network, quadratic SVM, neural net
Objavljeno: 30.06.2022; Ogledov: 478; Prenosov: 0
.pdf Polno besedilo (1018,61 KB)

Development of Zinc Oxide-Multi-Walled Carbon Nanotube hybrid nanofluid for energy-efficient heat transfer application: A thermal lens study
Swapna Mohanachandran Nair Sindhu, 2021, izvirni znanstveni članek

Opis: This paper addresses the need for developing an energy-efficient hybrid nanofluid with zinc oxide–multi-walled carbon nanotube (ZnO-MWCNT) for overcoming the bottleneck of efficient heat transfer in thermal systems. The concentration-dependent thermal diffusivity modifications are analyzed using the highly sensitive mode mismatched thermal lens technique. The hybrid composite is prepared by the solid-state mixing and annealing of a pure multi-walled carbon nanotube (MWCNT) and zinc oxide (ZnO), synthesized by the solution combustion method. The composite formation is studied by structural, morphological, and optical characterization techniques. Among the three nanofluids ZnO, MWCNT, and ZnO-MWCNT, the composite exhibits a drastic enhancement in thermal diffusivity at a lower solid volume fraction of 0.047 mg/ml containing 0.009 mg/ml of MWCNT. All the nanofluids show an optimum concentration beyond which the thermal diffusivity decreases with the nanoparticle concentration. Thus, this study suggests the potential application of ZnO-MWCNT hybrid nanofluids in thermal system design to enhance internal combustion engines' efficiency during cold-start.
Najdeno v: osebi
Ključne besede: Zinc Oxide, MWCNT, hybrid nanofluid, thermal lens, diffusivity, engine efficiency
Objavljeno: 30.06.2022; Ogledov: 501; Prenosov: 0
.pdf Polno besedilo (2,44 MB)

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