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Phapale K.,IITBombay | Singh R.,IITBombay | Patil S.,Bharat Forge Ltd. Pune | Singh R.K.P.,Bharat Forge Ltd. Pune
Procedia Manufacturing | Year: 2016

Composite laminates are used in many applications in industries like aerospace and aircraft due to their extremely high strength to weight ratio and corrosion resistance properties. The composite laminates are difficult to machine materials, which results into low drilling efficiency and drilling-induced delamination, thus it is important to develop an innovative advanced drilling process to overcome the difficulties related in the machining of composite materials. This work is focused on comprehensive experimental characterization to understand the effect of cutting parameters on the delamination extent during abrasive water jet drilling of carbon fiber reinforced polymer. Processing parameters, such as standoff distance and water pressure plays dominant role in delamination than abrasive flow rate. It also describes the development of different techniques for controlling the delamination in abrasive water jet drilling process, such as backup plate, pre-drilled hole and water immersion (under water). The analysis shows that abrasive water jet drilling with backup plate yields lower delamination, hole size variation and hole surface roughness. © 2016 The Authors

Bera B.K.,Indian StatisticalInstitute | Ghosh D.,Indian StatisticalInstitute | Parmananda P.,IITBombay | Osipov G.V.,Nizhny Novgorod State Technical University | Dana S.K.,Jadavpur University
Chaos | Year: 2017

We report the emergence of coexisting synchronous and asynchronous subpopulations ofoscillators in one dimensional arrays of identical oscillators by applying a self-feedbackcontrol. When a self-feedback is applied to a subpopulation of the array, similar tochimera states, it splits into two/more sub-subpopulations coexisting in coherent andincoherent states for a range of self-feedback strength. By tuning the coupling betweenthe nearest neighbors and the amount of self-feedback in the perturbed subpopulation, thesize of the coherent and the incoherent sub-subpopulations in the array can be controlled,although the exact size of them is unpredictable. We present numerical evidence using theLandau-Stuart system and the Kuramoto-Sakaguchi phase model. © 2017 Author(s).

Mohapatra P.K.,IITBombay | Kushavah D.,Indian Institute of Technology Bombay | Mohapatra J.,Indian Institute of Technology Bombay | Singh B.P.,IITBombay
AIP Conference Proceedings | Year: 2015

Highly luminescent graphene quantum dots (GQDs) are synthesized through thermolysis of glucose. The average lateral size of the synthesized GQDs is found to be ∼5 nm. The occurrence of D and G band at 1345 and 1580 cm-1 in Raman spectrum confirms the presence of graphene layers. GQDs are mostly consisting of 3 to 4 graphene layers as confirmed from the AFM measurements. Photoluminescence (PL) measurement shows a distinct broadening of the spectrum when GQDs are on the semiconducting bulk surface compared to GQDs in water. The time resolved PL measurement shows a significant shortening in PL lifetime due to the substrate interaction on GQDs compared to the GQDs in solution phase. © 2015 AIP Publishing LLC.

Karamchandani S.H.,IITBombay | Mustafa H.D.,IITBombay | Mustafa H.D.,Tulane University | Merchant S.N.,IITBombay | Desai U.B.,IITHyderabad
Proceedings of the IEEE | Year: 2012

The paper presents a new paradigm from the perspective of pervasive on-body computing through an innovative polymerized textile, which exhibits sensing and radiation properties. A radical, first of its kind, sensor fabricated from unsaturated polymer resin textile, establishes a dynamic link connecting human thermodynamics to electrical ambiance. A dynamic fabrication process of esterification and $\eta$-polymerization is developed, which is articulately arrested using an innovatively formulated retardant, yielding a permanent thermally unstable partially oriented yarn (tuPOY). A prudently established nontrivial interchange phenomenon is founded, presenting an inimitable calibration mechanism of the sensors and charting a novel relationship of exuberated energy to lattice kinetics of tuPOY. This meticulously researched conducting medium of tuPOY, fabricated from aromatic polyamides, also presents an avant-garde architecture for proliferation of electrical and thermal signals concomitantly between the sensors and its transmission circuit. A power generating unit (PGU) delineates the power mining from thermal energy dissipated from the body, presenting a new dimension in operational power dynamics. A textile composite antenna is premeditated exclusively from radiating tuPOY-based patch and substrate, an archetype reporting in published literature. The judiciously designed antenna, with tuPOY coupled as its patch, and substrate operate as shields against the radiations directed towards the body leading to a self-sustained sculpt. The back-end hardware of the test setup conceptualizes an automated physician machine (APM) presenting a standalone architecture. The artificial intelligence core of APM is modeled on weighted multiclass support vector machines (wmSVMs). The capturing of signal variations, devoid of any metallic components, presents a singular facet of research and amalgamates various interdisciplinary fields, while providing a robust architecture with minimum tradeoffs. © 1963-2012 IEEE.

Pareek Y.,IITBombay | Ravikanth M.,IITBombay
European Journal of Organic Chemistry | Year: 2011

A series of mono-functionalized core-modified expanded porphyrin building blocks such as thiasapphyrin, thiarubyrin, oxasmaragdyrin, and BF 2-oxasmaragdyrin have been synthesized by simple condensation of readily available precursors. The mono-functionalized core-modified expanded porphyrin building blocks were used to synthesize the first three examples of covalently linked diphenylethyne-bridged dyads containing two different expanded porphyrin macrocycles, namely thaisapphyrin-BF 2-oxasmaragdyrin, thiarubyrin-BF 2-oxasmaragdyrin, and thiasapphyrin-thiarubyrin, by coupling appropriate mono-functionalized expanded porphyrin building blocks under mild Pd 0 coupling reaction conditions. The three dyads were freely soluble in common organic solvents and characterized by MS, NMR, absorption, electrochemical, and fluorescence techniques. The NMR, absorption, and electrochemical studies indicated that the two macrocycles in the dyads interact weakly with each other and maintain their independent characteristic features. The steady-state fluorescence studies of the dyads showed that the thiasapphyrin and thiarubyrin units are nonfluorescent but fluorescence was observed from the BF 2-oxasmaragdyrin unit. However, the quantum yield of the BF 2-oxasmaragdyrin unit in the dyads was less than that of monomeric BF 2-oxasmaragdyrin because of an enhancement of nonradiative decay channels operating in the dyads. The potential use of two of the three dyads containing the BF 2-smaragdyrin subunit as fluorescent sensors for anions was explored. The studies showed that the binding of the anion at the protonated sapphyrin and rubyrin sites in the respective dyads can be followed by the clear changes in the fluorescence band of the BF 2-oxasmaragdyrin unit, which indicates that these dyads can be used as fluorescent anion sensors. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Patnaik P.,I.I.T.Bombay | Mukhopadhyay G.,I.I.T.Bombay | Singh P.P.,I.I.T.Bombay
AIP Conference Proceedings | Year: 2011

We report here our study on SiC doped with transition metals using first principle density functional theory calculations. We have considered cubic SiC with 3d transition metals as substitutional impurities for Si and C site separately. Cubic SiC doped with Cr, Mn, show ferromagnetism whereas with Sc, Ti, V and Co show site dependency of magnetic properties. Rests of the impurities are found to be non-magnetic. © 2011 American Institute of Physics.

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