Indian Institute of Technology Hyderabad
Research Archive of Indian Institute of Technology HyderabadNot a member yet
10644 research outputs found
Sort by
Damage characterization of CFRP laminates using acoustic emission and digital image correlation: Clustering, damage identification and classification
Full text linkDamage mechanisms in composite laminates are quite complex, and it is necessary to perceive their effects on the degradation of laminate mechanical properties. This work employs acoustic emission (AE) and digital image correlation (DIC) techniques to describe the evolution of intra/inter-laminar damage modes in the CFRP laminates under in-plane/out-of-plane loading conditions. In this study, laminates of stacking sequences
,
,
, and
under tensile load are investigated to distinguish the intra-laminar damages like matrix cracking, fiber–matrix debond, and fiber breakage. Double cantilever beam, end notch flexure, and mixed-mode bending specimens are used to characterize delamination failure in the laminate. An unsupervised
-means clustering technique is used to classify the AE data based on peak frequency and amplitude. The surface displacement and strain data are evaluated using the DIC technique to understand the damage evolution in the laminates. Post failure analysis is carried out using a digital microscope, and fractography studies are used to identify and assign the damages to different AE clusters. This investigation yields a taxonomy of damage modes, their sequence of occurrence, and failure strains that can be used for structural health monitoring and progressive damage modeling of composite laminates
Pigment epithelial detachment composition indices (PEDCI) in neovascular age-related macular degeneration
Full text linkWe provide an automated analysis of the pigment epithelial detachments (PEDs) in neovascular age related macular degeneration (nAMD) and estimate areas of serous, neovascular, and fibrous tissues within PEDs. A retrospective analysis of high-definition spectral-domain OCT B-scans from 43 eyes of 37 patients with nAMD with presence of fibrovascular PED was done. PEDs were manually segmented and then filtered using 2D kernels to classify pixels within the PED as serous, neovascular, or fibrous. A set of PED composition indices were calculated on a per-image basis using relative PED area of serous (PEDCI-S), neovascular (PEDCI-N), and fibrous (PEDCI-F) tissue. Accuracy of segmentation and classification within the PED were graded in masked fashion. Mean overall intra-observer repeatability and inter-observer reproducibility were 0.86 +/- 0.07 and 0.86 +/- 0.03 respectively using intraclass correlations. The mean graded scores were 96.99 +/- 8.18, 92.12 +/- 7.97, 91.48 +/- 8.93, and 92.29 +/- 8.97 for segmentation, serous, neovascular, and fibrous respectively. Mean (range) PEDCI-S, PEDCI-N, and PEDCI-F were 0.253 (0-0.952), 0.554 (0-1), and 0.193 (0-0.693). A kernel-based image processing approach demonstrates potential for approximating PED composition. Evaluating follow up changes during nAMD treatment with respect to PEDCI would be useful for further clinical applications
Sustainable enzymatic treatment of organic waste in a framework of circular economy
Full text linkEnzymatic treatment of food and vegetable waste (FVW) is an eco-friendly approach for producing industrially relevant value-added products. This review describes the sources, activities and potential applications of crucial enzymes in FVW valorization. The specific roles of amylase, cellulase, xylanase, ligninase, protease, pectinase, tannase, lipase and zymase enzymes were explained. The exhaustive list of value-added products that could be produced from FVW is presented. FVW valorization through enzymatic and whole-cell enzymatic valorization was compared. The note on global firms specialized in enzyme production reiterates the economic importance of enzymatic treatment. This review provides information on choosing an efficient enzymatic FVW treatment strategy, such as nanoenzyme and cross-linked based enzyme immobilization, to make the process viable, sustainable and cheaper. Finally, the importance of life cycle assessment of enzymatic valorization of FVW was impressed to prove this approach is a better option to shift from a linear to a circular economy
Features of near gravitational material tracers in a dense medium cyclone from PEPT
Full text linkDense media cyclones are an integral part of circuits employed for coal processing, iron ore beneficiation, and recovery of diamonds. Many techniques have been applied in studying the separation performance of these devices including the use of different density tracers to develop density partition curves. This study focusses on tracking of near-gravity material radioactive tracers using the positron emission particle tracking technology. This near-gravity phase of coal has long been thought to cause separation inefficiencies which makes coal processing difficult. In this work, a slurry containing magnetite-based dense medium, and coal is pumped through a 100 mm Multotec cyclone. By means of the PEPT camera – apparatus with spatial and temporal resolutions of 1 mm and 1 ms respectively – and direct-adsorption-activated coal tracer particles within the medium, particle trajectories are recorded in space and time. The free vortex region is captured and shown to fit the Rankine vortex behaviour with n = 0.60 ± 0.08 overall for the free vortex power law decay. A logarithmic axial velocity model which captures the observed radial gradient around the locus of zero axial velocity is proposed. Radial profiles of turbulence intensity for the near gravitational material as captured by PEPT are presented
Combustion characteristics of lithium perchlorate-based electrically controlled solid propellants at elevated pressures
Full text linkElectrically controlled solid propellants (ECSPs) exhibit specific combustion characteristics that offer multiple start/stop operations and variable combustion rates at different electrical power. The present study investigates ignition and pyroelectric combustion characteristics of ECSPs, based on lithium perchlorate (LP) oxidizer and poly vinyl alcohol (PVA) binder, in the elevated pressure range of 0.1 to 2.0 MPa, and to further understand the performance of tungsten (W) as a metal additive. Experiments are conducted for metallized ECSPs with 5% (M5), 10% (M10) and 15% (M15) W content, relative to the non-metallized case. Ignition delay time (Tign) for the baseline (M0) decreased substantially from 633 ms at 0.1 MPa to 178 ms at 2.0 MPa pressure. A similar decreasing trend for the minimum electrical energy required for ignition was also observed with increase in pressure. Addition of W decreased Tign and electrical ignition energy significantly by 33% and 66% respectively, for M15 relative to M0. Furthermore, thermochemical equilibrium analysis indicated that the adiabatic combustion temperature and specific impulse decreased with increase in W content due to increased fuel-rich stoichiometry. Overall, the metal addition significantly enhanced the combustion rates at all pressure range below 2.0 MPa. It is anticipated that the observed characteristics at elevated pressures provide insights into the design of electrically-controlled operations for future propulsion systems
On the nature of flow curve and categorization of thixotropic yield stress materials
Full text linkThixotropy is a phenomenon related to time dependent change in viscosity in the presence or absence of flow. The yield stress, on the other hand, represents the minimum value of stress above which steady flow can be sustained. In addition, the yield stress of a material may also change as a function of time. Both these characteristic features in a material strongly influence the steady state flow curve of the same. This study aims to understand the interrelation between thixotropy, yield stress, and their relation with the flow curve. In this regard, we study five thixotropic materials that show yield stress. The relaxation time of all the five systems shows power-law dependence on aging time with behaviors ranging from weaker than linear, linear to stronger than linear. Furthermore, the elastic modulus and yield stress have been observed to be constant for some systems while time dependent for the others. We also analyze the experimental behavior through a viscoelastic thixotropic structural kinetic model that predicts the observed experimental behavior of constant as well as time-dependent yield stress quite well. These findings indicate that a nonmonotonic steady-state flow curve in a structural kinetic formalism necessarily leads to time-dependent yield stress, while constant yield stress is predicted by a monotonic steady-state flow curve with stress plateau in the limit of low shear rates. The present work, therefore, shows that thixotropic materials may exhibit either monotonic or nonmonotonic flow curves. Consequently, thixotropic materials may show no yield stress, constant yield stress, or time-dependent yield stress
Deciphering colour building blocks of massive multiparton amplitudes at 4-loops and beyond
Full text linkThe soft function in non-abelian gauge theories exponentiate, and their logarithms can be organised in terms of the collections of Feynman diagrams called Cwebs. The colour factors that appear in the logarithm are controlled by the web mixing matrices. Direct construction of the diagonal blocks of Cwebs using the new concepts of Normal ordering, basis Cweb and Fused-Web was recently carried out in [1]. In this article we establish correspondence between the boomerang webs introduced in [2] and non-boomerang Cwebs. We use this correspondence together with Uniqueness theorem and Fused web formalism introduced in [1] to obtain the diagonal blocks of four general classes of Cwebs to all orders in perturbation theory which also cover all the four loop Boomerang Cwebs connecting four Wilson lines. We also fully construct the mixing matrix of a special Cweb to all orders in perturbation theory
Ambipolar Electrochemistry of Pre-Intercalated Ti3C2Tx MXene in Ionic Liquid Electrolyte
No full textCation intercalation with or without redox remains the dominant charge storage mechanism for two-dimensional (2D) Ti3C2Tx MXene. Anion-based charge storage remains unexplored due to intrinsic negative surface charge of MXenes preventing spontaneous intercalation of anions and irreversible oxidation of Ti at anodic potentials in aqueous electrolytes. In this work, we report on the ambipolar electrochemical behavior of the Ti3C2Tx in ionic liquid electrolyte over a 2.5 V electrochemically stable window. The experiments are conducted on a thin Ti3C2Tx film current collector coated with an electroactive layer of small flakes (∼150 nm) of Ti3C2Tx pre-intercalated with 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMIM-TFSI) ionic liquid. Couples of redox peaks with a very small potential separation during the voltage sweep are observed at high negative (−0.75 V vs. Ag wire) and high positive (+0.75 V vs. Ag wire) potentials. Our experimental electrochemical data combined with density functional theory (DFT) calculations suggest feasibility of pseudo-intercalation of TFSI anions between Ti3C2Tx flakes. This study provides a pathway for elucidating anion intercalation for different MXene chemistries in solvent-free electrolytes, which can lead to development of MXene based energy storage devices with improved performance
Single-molecule tracking dataset of histone H3 (Hht1) in Saccharomyces cerevisiae
Full text linkSingle-Molecule Tracking (SMT) is a powerful method to quantify protein dynamics in live cells. Recently, we have established a data analysis pipeline for estimating various biophysical parameters (mean squared displacement, diffusion coefficient, bound fraction, residence time, jump distances, jump angles, and track statistics) from the single-molecule time-lapse movies acquired from yeast Saccharomyces cerevisiae. We acquired the time-lapse movies using different time intervals (i.e. 15 ms, 200 ms, and 1000 ms) to extract the diffusion parameters (from 15 ms time interval movies) and residence time (from 200 ms and 1000 ms time interval movies). We tracked the single molecules from these movies using three MATLAB-based software packages (MatlabTrack, TrackIT, DiaTrack (Sojourner, and Spot-On)) to quantify various biophysical parameters. In this article, we have quantified the biophysical parameters of chromatin-bound histone H3 (Hht1), labeled using JF646 HaloTag Ligand (HTL), and shared a few raw time-lapse SMT movies for the same. Histone H3 is a chromatin-bound protein and it serves as a benchmark for the stably bound molecules for the SMT experiments. Hence, this dataset can be used by various researchers to quantify the biophysical parameters of chromatin-bound molecules (Histone H3). Any newly developed tracking software can use this dataset to validate the accuracy of its tracking algorithms
Tungsten oxysulfide nanoparticles interspersed nylon based e-textile as a low cost, wearable multifunctional platform for ultra-sensitive tactile sensing and breath sensing applications
Full text linkIn this work, we report the hydrothermal synthesis of Tungsten Oxysulfide (WS2|O) nanoparticles interspersed onto porous, lightweight Nylon fabric as a clean-room-free, multifunctional sensor for detection of human breath, strain, and pressure. Morphological characterizations reveal the uniform dispersion of the conductive WS2|O nanosheets across the ultra-thin fibers of nylon. The fabricated WS2|O@nylon-based device as a breath sensor exhibits excellent sensitivity towards different breath patterns. The optimization studies resulted in a 4-layered high-performance piezoresistive wearable pressure sensor. It exhibited a sensitivity of 1.5 kPa−1, response time of 0.2 sec over a dynamic range of 50 Pa to 350 Pa. A Gauge factor of 24.2 and good mechanical stability across 10,000 cycles of compressive strain exhibited by the strain sensor makes it suitable for gesture recognition. The exceptional sensitivity, stability with good flexibility prove it as a promising device platform for the development of various wearable multifunctional sensor applications