IR@CMERI - The Central Mechanical Engineering Research Institute (CSIR)
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Experimental and computational studies of imidazolium based ionic liquid 1-methyl- 3-propylimidazolium iodide on mild steel corrosion in acidic solution
No full textCorrosion inhibitive property of ionic liquid 1-Methyl-3-propylimidazolium iodide (MPII) on Mild Steel in 1 M H2SO4 was investigated by experimental and computational Studies. The inhibition efficiency of inhibitor MPII at various concentrations, temperature and time duration were studied by gravimetric measurements, potentiodynamic polarization techniques, electrochemical impedance spectroscopy (EIS), surface studies and computational studies. The results from potentiodynamic polarization studies revealed that inhibitor 1-Methyl- 3-propylimidazolium iodide acts as a mixed type inhibitor with a high inhibition efficiency of 91% at 298 K. Adsorption of the inhibitor on the surface of mild steel follows the Langmuir adsorption isotherm. The mechanism of adsorption was also validated by quantum chemical studies. Morphology and topography of the Mild Steel surface with and without the inhibitor were investigated by SEM. Thermodynamic parameters for adsorption like adsorption equilibrium (), Free energy of adsorption i.e. ΔGads were also calculated so as to project the mechanism of adsorption. Computational data obtained from the Density functional theory (DFT) were used to acquire detailed theoretical insights. Appreciably Electrochemical impedance spectroscopy, Molecular dynamic simulation and quantum chemical calculation confirms the interaction of inhibitor with metal which leads to increases in inhibition efficiency
Area Efficient VLSI Architectures for Weak Signal Detection in Additive Generalized Cauchy Noise
No full textDetection of a weak signal in additive Generalized Cauchy (GC) noise is important in many applications. The locally optimum detector (LOD) for a weak signal in GC noise is nonlinear in nature. When noise variance is unknown, the maximum likelihood estimator (MLE) is nonlinear and the resultant detector is complicated. Since VLSI implementation of complex nonlinearities is a challenging task, we develop an order statistics framework for detection in GC noise. We propose linear and ratio detectors, for weak signals in GC noise with known and unknown but deterministic variance, respectively. We provide extensive simulation results to show that performance loss of proposed linear and ratio detectors, is very small compared to LOD and nonlinear detector using MLE, respectively. We propose SORT−N (for running ordering of samples) and its VLSI architecture, using which we develop two-stage VLSI architectures for proposed linear and ratio detectors. Synthesis results for arbitrary waveform case indicate, for same throughput and latency, linear detector consumes lesser area to LOD, upto a sample size of N=64 . For same throughput, ratio detector renders substantial area savings (≈50%) over nonlinear detector using MLE, for any N . Finally, we propose a reconfigurable architecture for efficient realization of all the detectors
Synthesis and characterization of Cu2O nanoparticles
No full textCuprous oxide (Cu2O) nanoparticles are synthesized by aqueous precipitation method for the production of low-cost conductive ink, which is suitable for a printed, electronic application. The major drawback of copper ink, such as rapid oxidation overcomes by the formation of Cu2O ink. Structural characterizations reveal that spherical, nano-sized, polycrystalline cubic structure of Cu2O nanoparticles synthesized in the present work. The studies on transmission electron microscopies show that the size of these nanoparticles is approximately 7.5 ± 1.8 nm. The Cu2O nanoparticles show an absorption band at 650 nm with a bandgap of 2 eV. Results of sheet resistance and contact angle of Cu2O nanoparticles make it suitable for the development of low-cost conductive writing ink for a printed, electronic application
Corrosion inhibition property of azomethine functionalized triazole derivatives in 1 mol L−1 HCl medium for mild steel: Experimental and theoretical exploration
No full textWith the aim to explore the effect of heteroatoms on corrosion inhibiting efficacy of structurally similar azomethine based organic molecules, namely, 5-((furan-2-yl)methyleneamino)-2H-1,2,4-triazole-3-thiol (FMT) and 5-((thiophen-2-yl)methyleneamino)-2H-1,2,4-triazole-3-thiol (TMT) were synthesized and its corrosion inhibiting property were investigated by potentiodynamic polarization and non-destructive electrochemical impedance spectroscopy. These electrochemical techniques revealed the excellent corrosion inhibiting efficacy of synthesized inhibitor molecules for mild steel exposed to 1 molL−1 HCl at ambient condition. Surface analyses using FESEM, AFM and contact angle measurement of mild steel retrieved from corrosive medium containing inhibitor molecules confirmed the formation of protective layer of inhibitor molecules on its surface. The consequences of efficient corrosion inhibiting property has been explained based on Hard-Soft-Acid-Base principle as well as electronegativity and polarizability difference of heteroatoms present in the skeleton of inhibitor molecules. Moreover, in order to validate the corrosion inhibiting property obtained from electrochemical experimentations, the insight of corrosion inhibition mechanism has been further explored by employing theoretical calculations viz density functional theory, Fukui indices analyses, molecular dynamics simulation and radial distribution function. Mulliken atomic charges, frontier molecular orbital and Fukui indices analysis of the free as well as adsorbed inhibitor molecules confirms the interaction of the susceptible reactive sites
A Novel Methodology for Spark Gap Monitoring in Micro-EDM Using Optical Fiber Bragg Grating
No full textMicro-electric discharge machining (micro-EDM) is the most considerable micro-manufacturing process used to engineer miniaturized features on any high temperature resistive hard material. The machining parameters of micro-EDM are very stochastic in nature. The spark gap measure acts as a vital parameter that correlates with other process parameters for enhancement of the material removal rate (MRR) in micro-EDM. The real-time actual measurement of the spark gap between the electrodes is highly challenging and is limited due to the small gap measure. This article is about the development of a novel sensing technique for spark gap measurement, based on a fiber Bragg grating (FBG) sensor. The sensing system is developed on a cantilever structure bonded with the FBG sensor, for performing accurate spark gap measurements with the displacement measurement of the tool electrode. The deflection on the cantilever during spark gap generation is translated into strain variations, as monitored by the FBG bonded over it. Experimental trials are conducted on the micro-EDM setup with the cantilever beam-based displacement sensing with a sensitivity of 10 μm/pm. Real-time spark gap data obtained by FBG are in the range of 1.1-18.6 μm and are validated against a precision measuring instrument. This sensing technology employed for micro-EDM spark gap measurement establishes a novel technique in the micro-machining field and formulates a smart system
A wave packet enriched finite element for electroelastic wave propagation problems
No full textA two dimensional finite element (FE) is developed by enriching the conventional Lagrange interpolation functions with local element domain wave functions, for accurate solution of general wave propagation problems in piezoelastic media. The enrichment functions, applied to both displacement and electric potential fields, satisfy the partition of unity condition, and vanish at the nodes. The formulation is developed using the extended Hamilton’s principle for piezoelastic solids, considering two-way electromechanical coupling. The enriched FE is shown to perform equally well in terms of computational efficiency and accuracy for broadband impact induced electroelastic wave to narrowband ultrasonic guided wave propagation problems, unlike the other available elements. The solution for impact in a piezoelectric plate is shown to alleviate the spurious undulations in both velocity and electric potential fields, which are encountered in the conventional FE solutions. For the problem of high frequency Lamb wave actuation and sensing in a thin plate bonded with piezoelectric actuator/sensor patches, the element shows significant improvement in the computational efficiency over the conventional FE. Further, the free edge effect of steep gradients in the shear stress distribution at the actuator-plate interface is accurately captured by the proposed element using much fewer degrees of freedom than the conventional FE
Gold-nanoparticle-embedded microchannel array for enhanced power generation
No full textA high streaming potential and current were generated using a gold-nanoparticle-embedded patterned PDMS microchannel array. Gold nanoparticles with dimensions of ∼70 nm were prepared inside a hydrophobic patterned PDMS microchannel. The channel array was developed on a ridge-shaped patterned surface by performing soft lithography using UV-laser micromachining with a ridge spacing of 27.0 μm, width of 22.0 μm, and height of 16.0 μm. Subsequently, tests were conducted in which ultrapure water, solutions of 0.1 M NaCl, 0.1 M HCl and 40% H2O2 were passed through the patterned channel array at various flow rates and pressures using a microfluidic pump wherein the channel inlet and outlet acted as collector electrodes. A maximum streaming potential of 2.6 V, a current of 1.3 μA, and a maximum power density of 4.3 μW cm−2 were obtained for this gold-nanoparticle-embedded PDMS channel with ultrapure water as the working fluid at an inlet pressure of 1 bar. The generated power density here was ∼256 times higher than that for the PDMS channel array without gold nanoparticles using ultrapure water as the working fluid, confirming the benefit of gold nanoparticles in the channel array, which may have potential applications in microwatt-powered lab-on-chip devices
Design and development of non‐perfluorinated ionic polymer metal composite‐based flexible link manipulator for robotics assembly
No full text, cyclic voltammetry and linear sweep voltammetry, load characterization, and actuation performance confirm the excellent electrochemical and electromechanical response as compared with the other reported IPMCs. This method of fabrication exhibits significant advantages, such as the easy process of fabrication using non‐toxic materials. A two‐link flexible manipulator was developed, where the electromechanical behavior of polymer‐based actuator provides an important step for robotic assembly. This shows the potential of flexible compliant fingers and joints in flexible link manipulator for robotic assembly
Function space formulation of the 3-noded distorted Timoshenko metric beam element
No full textThe 3-noded metric Timoshenko beam element with an offset of the internal node from the element centre is used here to demonstrate the best-fit paradigm using function space formulation under locking and mesh distortion. The best-fit paradigm follows from the projection theorem describing finite element analysis which shows that the stresses computed by the displacement finite element procedure are the best approximation of the true stresses at an element level as well as global level. In this paper, closed form best-fit solutions are arrived for the 3-noded Timoshenko beam element through function space formulation by combining field consistency requirements and distortion effects for the element modelled in metric Cartesian coordinates. It is demonstrated through projection theorems how lock-free best-fit solutions are arrived even under mesh distortion by using a consistent definition for the shear strain field. It is shown how the field consistency enforced finite element solution differ from the best-fit solution by an extraneous response resulting from an additional spurious force vector. However, it can be observed that when the extraneous forces vanish fortuitously, the field consistent solution coincides with the best-fit strain solution
Electrochemical Detection of H₂O₂ Using Copper Oxide-Reduced Graphene Oxide Heterostructure
No full textThree dimensional heterostructure of CuO nanoparticle decorated reduced graphene oxide (rGO) was prepared by a facile and cost-effective technique. The structure and electrochemical properties of the CuO-rGO heterostructure composites were evaluated by various techniques. Transmission electron microscopy image analysis confirmed the presence of CuO nanoparticles onto the surface of the rGO sheets. It was also noticed that the electrochemical properties were dependent on the morphology of the heterostructure. The CuO-rGO heterostructure showed better hydrogen peroxide sensing performance as compared to the pure CuO nanoparticle. The sensitivity and limit of detection (LoD) were found to be 57.6 μA mM-1 cm-2 and 4.3 nM. The CuO-rGO heterostructure also showed good selectivity in the presence of various interfering electrolytes like ascorbic acid, dopamine, uric acid and glucose