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Singh R.,Indian Defence Institute of Advanced Technology | Kulkarni S.G.,Indian Defence Institute of Advanced Technology
International Journal of Polymeric Materials and Polymeric Biomaterials | Year: 2013

A number of polymer composite films using polyvinyl alcohol (PVA) as the preorganized polymer matrix were synthesized embedding different metal salts of transition elements like copper, cobalt, nickel, iron, cadmium, and zinc by a biomimetic route. The metal salts present in composites were reduced in situ to metallic form. The composites were characterized by FTIR, SEM, and EDAX. The SEM analysis confirmed the presence of nano-sized metal particles uniformly distributed in the polymer matrix. Mechanical properties were measured for various composite and PVA films. Significant improvement in some of the mechanical properties of polymer composites was realized in comparison with PVA. © 2013 Copyright Taylor and Francis Group, LLC.

Gonte R.R.,Indian Defence Institute of Advanced Technology | Balasubramanian K.,Indian Defence Institute of Advanced Technology
Journal of Hazardous Materials | Year: 2012

A simple method to convert gold from waste gold solutions used in chemical laboratories and chemical industries into metallic gold nano particles using styrene maleic acid copolymer beads has been approached. The styrene maleic acid copolymer beads with an average bead diameter 400-600 microns, exhibiting exceptionally high rough surface was used as a polymer matrix for the reducing gold from aqueous solution to metallic nano gold. Uptake of gold ions from aqueous waste gold solution was attempted in a batch process. Conversion of gold to metallic nano gold was achieved without the use of any external reducing agents. The metallic nano gold particles could be embedded into polymer matrix within 2. h. The beads exhibited high temperature resistance and could sustain upto 400. °C. © 2012 Elsevier B.V..

Panwar V.,Indian Defence Institute of Advanced Technology
ICMET 2010 - 2010 International Conference on Mechanical and Electrical Technology, Proceedings | Year: 2010

This paper presents a Lyapunov based approach to design an asymptotic trajectory tracking controller for robot manipulator using RBF neural network and an adaptive bound on disturbance terms. The controller is composed of computed torque type part, RBF network and an adaptive controller. The controller is able to learn the existing structured and unstructured uncertainties in the system in online manner. The RBF network learns the unknown part of the robot dynamics with no requirement of the offline training. The adaptive controller is used to estimate the unknown bounds on unstructured uncertainties and neural network reconstruction error. The overall system is proved to be asymptotically stable. Finally, the simulation results are performed on a Microbot type of manipulator to show the effectiveness of the controller. © 2010 IEEE.

Panigrahi S.K.,Indian Defence Institute of Advanced Technology
Composites Part B: Engineering | Year: 2013

This paper deals with the structural design of single lap joints (SLJs) with delaminated adherends using fracture mechanics principles. The interlaminar stresses and Strain Energy Release Rate (SERR) are considered as damage characterizing parameters used for designing the SLJ when delamination damages are pre-embedded in both the adherends at similar positions. Three dimensional geometrically non-linear finite element analyses (FEAs) of SLJ with delaminated adherends have been performed to determine the interlaminar and SERR values along the delamination fronts by simulating the simultaneous interaction delamination damages when pre-embedded at similar positions in both the adherends. SERR values are evaluated using Modified Crack Closure Technique (MCCI) which is based on energy principle. The delaminations are assumed to be of linear front, and have been considered to be embedded in both the laminated FRP composite adherends beneath the surface ply of the adhesively bonded SLJ. The delamination damages are presumed either to pre-exist or get evolved at the interlaminar locations. Such delaminations have been modelled using the sublaminate technique. The critical issues of modelling pre-embedded delamination damages are discussed in detail. The numerical results presented in this paper are based on the validated FE model compared with the available literature. Based on the present analyses, the structural design recommendations have been made for the SLJ when pre-embedded delamination damages are present in both the adherends. It is observed from the stress based design that the delamination damage when present in the bottom adherend is more detrimental for failure of SLJ compared to that for the case when it is present in the top adherend. Also, SERR based design reveals that the opening mode predominantly governs the propagation of delamination damage for all positions of the pre-embedded delaminations in both the adherends of the SLJ. © 2013 Elsevier Ltd.

Narendar S.,Indian Defence Institute of Advanced Technology | Gopalakrishnan S.,Indian Institute of Science
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2010

This paper presents the effect of nonlocal scaling parameter on the terahertz wave propagation in fluid filled single walled carbon nanotubes (SWCNTs). The SWCNT is modeled as a Timoshenko beam, including rotary inertia and transverse shear deformation by considering the nonlocal scale effects. A uniform fluid velocity of 1000 m/s is assumed. The analysis shows that, for a fluid filled SWCNT, the wavenumbers of flexural and shear waves will increase and the corresponding wave speeds will decrease as compared to an empty SWCNT. The nonlocal scale parameter introduces certain band gap region in both flexural and shear wave mode where no wave propagation occurs. This is manifested in the wavenumber plots as the region where the wavenumber tends to infinite (or wave speed tends to zero). The frequency at which this phenomenon occurs is called the "escape frequency". The effect of fluid density on the terahertz wave propagation in SWCNT is also studied and the analysis shows that as the fluid becomes denser, the wave speeds will decrease. The escape frequency decreases with increase in nonlocal scaling parameter, for both wave modes. We also show that the effect of fluid density and velocity are negligible on the escape frequencies of flexural and shear wave modes. © 2010 Elsevier B.V. All rights reserved.

Talole S.E.,Indian Defence Institute of Advanced Technology | Kolhe J.P.,Indian Defence Institute of Advanced Technology | Phadke S.B.,College of Engineering, Pune
IEEE Transactions on Industrial Electronics | Year: 2010

In this paper, a feedback linearization (FL)-based control law made implementable using an extended state observer (ESO) is proposed for the trajectory tracking control of a flexible-joint robotic system. The FL-based controller cannot be implemented unless the full transformed state vector is available. The design also requires exact knowledge of the system model making the controller performance sensitive to uncertainties. To address these issues, an ESO is designed, which estimates the state vector, as well as the uncertainties in an integrated manner. The FL controller uses the states estimated by ESO, and the effect of uncertainties is compensated by augmenting the FL controller with the ESO-estimated uncertainties. The closed-loop stability of the system under the proposed observercontroller structure is established. The effectiveness of the ESO in the estimation of the states and uncertainties and the effectiveness of the FL + ESO controller in tracking are demonstrated through simulations. Lastly, the efficacy of the proposed approach is validated through experimentation on Quanser's flexible-joint module. © 2010 IEEE.

Patil S.B.,Indian Defence Institute of Advanced Technology | Singh A.K.,Indian Defence Institute of Advanced Technology
Electrochimica Acta | Year: 2011

In the present study, we report the optimization of various deposition parameters viz. bath temperature, deposition time and current density to deposit densely packed and vertically aligned ZnO nanorod thin films on cost effective substrate, i.e. steel, by electrodeposition technique. The obtained vertically aligned ZnO nanorod thin films are sensitized by CdS quantum dots (QDs) and utilized for photoelectrochemical (PEC) cell application. Effect of redox electrolyte on the PEC cell properties of CdS QDs sensitized ZnO nanorod thin films is investigated using two different electrolytes viz. polysulfide and ferro(i)cyanide.1 CdS QDs, of around 10 nm in diameter, are synthesized by chemical bath deposition (CBD) method. The deposited ZnO nanorods having diameter in the range 100-120 nm showed hydrophobic nature, which changed to hydrophilic after CdS QDs sensitization. The maximum short circuit current density (Jsc) and open circuit voltage (Voc) are observed for ferro(i)cyanide electrolyte and are found to be 680 μA cm -2 and 520 mV, respectively, under 10 mW cm-2 of illumination. However, better photoelectrode stability is observed for polysulfide electrolyte. © 2011 Elsevier Ltd. All rights reserved.

Singh A.,Indian Defence Institute of Advanced Technology
Advanced Powder Technology | Year: 2010

The present study investigates the electrical and sensing properties of mechanically compacted pellets of nanosized zinc oxide powders synthesized by chemical method at room temperature in alcohol base using Triethanolamine (TEA) as capping agent. Synthesized ZnO particles has been characterized for its optical, structural, morphological properties using UV-VIS spectrophotometer, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The ZnO particles have hexagonal wurtzite structure and the particles are of 20-30 nm in size. The electrical properties of the prepared material have been investigated with Impedance Spectroscopy at different temperatures and frequencies and other laboratory setup. Resistivity, I-V curves, AC impedance of ZnO nanoparticles pellets with temperature was investigated and response was compared with commercial ZnO. Piezoelectric and oxygen sensing property of ZnO were also examined. Dynamic hysteresis of sintered ZnO pellet using axis ACCT TF analyzer 2000HS did not show polarization retention by sample. Oxygen sensing of ZnO pellet has been investigated for different concentrations of oxygen for the temperature range of 200-350 °C. The decrease of the current flow through the ZnO pellet with increasing oxygen concentration indicates the application of ZnO in oxygen sensing. The prepared ZnO particles were also used for preparing nanofluids of different concentrations and were characterized by measuring thermal conductivity using hot wire method which shows sigmoidal behavior over a temperature range of 10-50 °C. © 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Yadav R.,Indian Defence Institute of Advanced Technology | Kandasubramanian B.,Indian Defence Institute of Advanced Technology
Materials Letters | Year: 2013

Antibacterial membranes of crosslinked PVA embedded Azadirachta indica and Curcuma longa were fabricated with egg albumin as crosslinking agent. The antibacterial property of the developed membrane was evaluated using agar plate method against Gram-positive and Gram-negative bacteria. A. indica-PVA membrane yielded 3-4 cm zone of inhibition against both the bacteria. A clear parametric dependence of the large zone of inhibition in membrane on uniform distribution of the additives was observed. This cost effective method eliminates the use of elaborated and sophisticated equipment′s used to fabricate membranes for biomedical application like wound healing, antibacterial, anti-fungal etc. © 2013 Elsevier B.V.

Nalawade S.M.,Indian Defence Institute of Advanced Technology | Thakur H.V.,Indian Defence Institute of Advanced Technology
IEEE Photonics Technology Letters | Year: 2011

In this letter, the nonlinear photonic crystal fiber (NLPCF) has been exploited for the first time, as a high-temperature sensor based on the modal interferometric technique with a sensitivity that is remarkably higher along with low strain sensitivity. We have obtained a very high temperature sensitivity of 73pm/°C and a very low strain sensitivity of 0.93pm/με. The temperature to strain cross sensitivity is found to be significantly low in the very high range of temperature and strain. The proposed sensor may find application in strain-effective areas requiring accurate temperature measurement even at a high temperature range. © 2006 IEEE.

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