IR@CMERI - The Central Mechanical Engineering Research Institute (CSIR)
IR@CMERI - The Central Mechanical Engineering Research Institute (CSIR)Not a member yet
731 research outputs found
Sort by
Microstructural and Wear Properties of Annealed Medium Carbon Steel Plate (EN8) Cladded with Martensitic Stainless Steel (AISI410)
No full textLimited work on the wear properties of martensitic stainless-steel weld clads initiated this work which included investigations on microstructural and wear properties of cladded AISI 410 (filler wire)/EN 8 plates (substrate). Three layers of martensitic stainless steel (AISI 410) were deposited using metal inert gas (MIG) welding on medium carbon steel (EN 8) achieving a 51.5 ± 2.35 HRC of top layer. The elemental and phase fractions of the cladded layers indicated 98% martensite phase and retained austenite (2%). About 40% dilution was observed between EN 8 and the first weld layer. The results of tests carried out on pin on disc tribometer revealed an enhancement of anti-wear life of the martensitic weld cladded EN 8 by three times that of uncladded EN 8. The uncladded EN 8 plate suffered severe damage and high wear, leading to its failure at 478 s. The failure of the uncladded EN 8 sample was identified by the occurrence of high vibration of the pin on disc tribometer which ultimately stopped the tribometer. On the other hand, the cladded EN 8 sample continued running for 3600 s, exhibiting normal wear. After the tribo test, the surfaces of the pins of both cladded and uncladded EN 8 were analyzed using scanning electron microscope (SEM) and 3D profilometer. The surface characterization of tribo pairs indicated ploughing and galling to be the primary wear mechanisms. The average grain size of top and middle layer was in the range of 2–3.5 µm, while the base metal showed 5.02 µm mean grain size, resulting in higher hardness of clad layers than base metal, also favoring better wear resistance of the cladded EN 8 samples as compared to uncladded EN 8 samples
Understanding the Synergistic Effect in Oxygen Evolution Reaction Catalysis from Chemical Kinetics Point of View: An Iron Oxide/Nickel Oxide Case Study
No full textThe Oxygen Evolution reaction (OER) is still an enigmatic process, and a few research efforts have been deployed to understand its thermodynamic aspects. However, to date, no significant attention has been given to understand the chemical kinetics of the OER. Herein, the oxides of nickel and iron, and their heterostructure were chosen for the investigation. The electrocatalytic activity was found to augment synergistically when a heterostructure was formed between iron oxide and nickel oxide. The metal oxide catalyzed OER was an entropy-driven process and followed the peroxide linkage formation pathway. The rate-determining step was found to be different for the reactions catalyzed by different oxides. For the first time, Distribution of relaxation time (DRT) plots were utilized to study the chemical kinetics of OER, and the inference obtained from this analysis agreed well with the reaction mechanism. The kinetic barrier for the charge transfer process was found to decrease, and the surface group formation attained a moderate value after the heterostructure formation. These aspects had been the key player behind the synergistic increment in OER catalytic activity of the heterostructure. This investigation will lead a new pathway towards the development of strategies to understand the kinetics of an electrochemical reaction
Hybrid controller for precision positioning application
No full textIn this paper, a precision positioning hybrid controller for long travel distance with submicron/nanometer resolution and accuracy is designed and developed. A hybrid control algorithm is designed to combine the coarse positioning system and a precision positioning system. The coarse positioning system consists of a linear stepper motor and coarse positioning controller, which is designed by microstepping with proportional-integral (PI) current feedback (MSPICF) control. In the precision positioning system, a piezoelectric actuator (PZA) is used. The mathematical model of the PZA has been represented by 2nd order mass-spring system with the Dahl hysteresis model and the model parameters are estimated by an autoregressive with exogenous terms (ARX) model identification technique using the input–output experimental data. The precision positioning controller designed by feedforward (FF) control which is the inverse of the mathematical model of the PZA and feedback (FB) control. The coarse, precision and hybrid controller is implemented using a low-cost DsPIC30F4012 microcontroller. Experiments have been performed to evaluate the performance of the controller
Tandem detection of sub-nano molar level CN and Hg2+ in aqueous medium by suitable molecular sensor: a viable solution for detection of CN and development of RGB based sensory device
No full textAn inimitable urea-based multichannel chemosensor, DTPH [1,5-bis-(2,6-dichloro-4-(trifluoromethyl)phenyl)carbonohydrazide], was examined to be highly proficient to recognize CN– based on the H-bonding interaction between sensor −NH moiety and CN– in aqueous medium with explicit selectivity. In the absorption spectral titration of DTPH, a new peak at higher wavelength was emerged in titrimetric analytical studies of CN– with the zero-order reaction kinetics affirming the substantial sensor–analyte interaction. The isothermal titration calorimetry (ITC) experiment further affirmed that the sensing process was highly spontaneous with the Gibbs free energy of −26 × 104 cal/mol. The binding approach between DTPH and CN– was also validated by more than a few experimental studies by means of several spectroscopic tools along with the theoretical calculations. A very low detection limit of the chemosensor toward CN– (0.15 ppm) further instigated to design an RGB-based sensory device based on the colorimetric upshots of the chemosensor in order to develop a distinct perception regarding the presence of innocuous or precarious level of the CN– in a contaminated solution. Moreover, the reversibility of the sensor in the presence of CN– and Hg2+ originated a logic gate mimic ensemble. Additionally, the real-field along with the in vitro CN– detection efficiency of the photostable DTPH was also accomplished by using various biological specimens
Characterization and actuation behavior of SPS/SGO ion exchange polymer actuator based on PEDOT: PSS/SGO composite electrode
No full textThis paper studied the fabrication of new hybrid-type poly(3,4- ethylene dioxythiophene) (PEDOT)/sulfonated graphene oxide electrode-based polymer actuator produced by film casting method. Sulfonated Poly(1,4-phenylene ether-ether sulfone) (SPS) ion-exchange polymer membrane-based ionic polymer composite actuators were fabricated using the different concentration of SGO. The characterization and actuation were demonstrated. By altering SGO concentration, four different SPS based membrane actuators were analyzed. The effects of SGO concentration on the morphology, proton conductivity, ion exchange capacity, and water uptake capability were studied. The maximum tip displacement and force by varying concentration of SGO were evaluated for the actuation performance
Thermal degradation of waste plastics under non-sweeping atmosphere: Part 2: Effect of process temperature on product characteristics and their future applications
No full textThe current energy demand and diminishing conventional fuels have forced researchers to find an alternative source of energy. Waste to energy is the current trend for converting waste materials (plastic waste) into valuable fuels. This article mainly discussed the detailed characterization of the pyrolytic products, their comparative analysis and the reaction mechanism at varying operating temperature. This article is a successor of part 1, which primarily focused on the characterization of different waste plastics, their TG analysis, the effect of reactor temperature on yield analysis in a batch reactor and their detailed degradation mechanism. Furthermore, the results presented in this article report the characterization of products at three processing temperatures of 450, 500 and 550 °C. The pyrolytic oils from all wastes excluding PS show a very low density ranging from 0.71 to 0.76 kg/m3, whereas PS pyrolytic density is reported between 0.86 and 0.88 kg/m3. The viscosity of oils increases with an increase in the processing temperature and is similar to the conventional fuels. The FTIR analysis of the products (oil & gases) obtained from HDPE, PP and mixed plastic waste (MIX) shows a large presence of alkanes and a higher presence of aromatics. PS analysis reported a large presence of aromatics (~75%). The GC-MS analysis of all pyrolytic oils from waste plastics, simulated wastes (virgin plastics) and distilled fraction of MIX pyrolysis oil is compared. The GC analysis of non-condensable gases at all processing temperature reports that MIX produce the maximum H2; HDPE, PS and MIX produces a high amounts of CH4 too. The formation of lower hydrocarbons (C5–C12) in pyrolysis oil shows a trend as MIX > PP > PS > HDPE, while for the heavier hydrocarbons (>C19) it is HDPE > PP > PS > MIX. The potential of the utilization of these products has been discussed in different sectors for future research
Development of 6-Thioguanine conjugated PLGA nanoparticles through thioester bond formation: Benefits of electrospray mediated drug encapsulation and sustained release in cancer therapeutic applications
No full textPolymeric nanoparticle-based successful delivery of hydrophobic drugs is highly desirable for its controlled and sustained release at the disease site, which is a challenge with the current synthesis methods. In the present study, an electrospray mediated facile one-step synthesis approach is explored in which a solution mixture of a hydrophobic drug, 6-thioguanine (Tg) and a biocompatible FDA approved polymer, Poly (d, l-lactide-co-glycolide) (PLGA) is injected in an applied electric field of suitable intensity to prepare drug encapsulated PLGA nanoparticles, PLGA-Tg with high yield. In order to explore the effect of external electric field on Tg loading and delivery applications, the nanoparticles are characterized using EDX, AFM, FESEM, TEM, FTIR, Raman, fluorescence, and mass spectroscopy techniques. The characterization studies indicate that the electric field mediated synthesis exhibits spherical nanoparticles with a homogenous core size distribution of ~60 nm, high encapsulation (~97.22%) and stable conjugation of Tg (via thioester linkages) with PLGA molecules in the presence of the applied electric field. The kinetic study demonstrates the ‘anomalous diffusion’ (non-Fickian diffusion) release mechanism in which Tg escapes from PLGA matrix with a slow, but steady diffusion rate and the sustained drug release profile continues for 60 days. To check the biological activity of the encapsulated Tg, in-vitro cell studies of the PLGA-Tg are performed on HeLa cells. The MTT assay shows significant cell death after 48 h of treatment, and the cellular internalization of the drug-loaded nanoparticles occurs through pinocytosis mediated uptake, which is established by the AFM analysis. The Raman and mass spectroscopy studies suggest that the PLGA-Tg nanoparticles are rapidly hydrolyzed inside cell cytoplasm to release Tg which initiates apoptosis-mediated cell death confirmed by as DNA fragmentation and membrane blebbing studies. The results clearly emphasize the benefits of electrospray based synthesis of polymeric nanodrug formulation through the formation of chemical bonds between polymer and drug molecules that could be easily implemented in the design and development of an effective nanotherapeutic platform with no typical ‘burst effect,’ prolonged release profile, and significant toxicity to the cancer cells
Analysis and comparative studies on impact of Transport Delay and Transforms on the performance of TD-PLL for single phase GCI under grid disturbances
No full textTransport delay – phase-locked loop (TD-PLL) techniques have gained much attention in recent years for designing single-phase PLL for Grid-Connected Inverters (GCIs) owing to its simple implementation structure. Some earlier works are available on design guidelines for selecting appropriate parameters of TD-PLL, but, the impact of transport delay (TD) and transformation matrix (TM) on the TD-PLL under different grid disturbances have yet not been explored in the literature. In this paper, all possible combinations of TD and TM for phase detector (PD) are explored and mathematically evaluated using small-signal and phasor analyses. Synchronization capabilities of PDs under grid disturbances were evaluated in terms of parameters like initial synchronizing speed, phase, and frequency estimation. The elements of TD-PLL responsible for the phase of synchronization and performance deviation under different grid disturbances were identified. It is also mathematically shown that the Ts/4 (a quarter of a period) TD-PLL offers better immunity against grid disturbances, faster dynamics, small settling time in comparison to its 3Ts/4 counterpart. Numerical results using MATLAB/Simulink environment as well as the experimental results obtained using dSPACE (DS1104) were presented to validate the theoretical analyses. The results were also compared with some advanced single-phase PLLs
Adsorption and anti-corrosion characteristics of vanillin Schiff bases on mild steel in 1 M HCl: experimental and theoretical study
No full textHerein, two Schiff base derivatives of vanillin and divanillin with 2-picolylamine, namely, 2-methoxy-4-((pyridin-2-ylmethylimino)methyl)phenol (compound A) and 3,3′-dimethoxy-5,5′-bis-((pyridin-2-ylmethylimino)methyl)-[1,1′-biphenyl]-2,2′-diol (compound B), respectively, were synthesized. Additionally, their adsorption characteristics and corrosion inhibition behavior were compared for mild steel in 1 M HCl using electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss methods. Compound B was found to impart a better anti-corrosive effect (around 95% inhibition efficiency at 313 K) than compound A. The inhibitors act as effective mixed-type inhibitors and exhibit Langmuir-type adsorption behaviour. The kinetic–thermodynamic parameters together with the data obtained from density functional theory (DFT) and molecular dynamics (MD) simulations illustrate the mechanism of corrosion and mode of adsorption of both inhibitors on the metal surface. The better corrosion mitigation propensity of the dimeric form of the inhibitor (compound B) over the monomeric form (compound A) was tested experimentally and explained according to the theoretical data
Inverse analysis and multi-objective optimization of coupling mechanism based laser-forming process
No full textLaser forming of non-developable surfaces necessitates simultaneous bending and shrinkage of the sheet blank. This can be obtained by coupling mechanism based laser forming. However, soft computing based modeling of this process as well as different laser parameter sets under coupling mechanism giving different optimum combinations of simultaneous bending and shrinkage is rarely reported. In this work, experiments have been carried out following a design of experiments with considered suitable ranges of the input factors, i.e., laser power, travel speed and laser beam diameter activating coupling mechanism. Response surface models for the outputs namely bending and thickening (resulted due to shrinkage) were developed in terms of the considered inputs and parametric effects were analyzed. Finite element modeling was also carried out to analyze the deformation behavior. Multi-objective optimization of laser parameters for different combinations of maximum/minimum of bending and thickening of the sheet material undergoing coupling mechanism has been shown. Forward and inverse models of the process have been built with the help of a backpropagation neural network (BPNN) and genetic algorithm-based neural network (GANN) based on experimental data. Because of the ability of genetic algorithm (GA) to obtain global search, GANN models provide better estimation of the input parameters for inverse modeling or process synthesis compared to that by the BPNN model. Finally, several dome-shaped surfaces were built with constant line energy but different Fourier numbers and hence, different proportions of bending and shrinkage. This was to demonstrate the importance of simultaneous bending and thickening of the sheet (achievable only by coupling mechanism) to generate such non-developable surface with minimal distortion