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Mohan R.R.,Cochin University of Science and Technology | Varma S.J.,Sanatana Dharma College | Faisal M.,PES Institute of Technology Bangalore South Campus | S J.,Cochin University of Science and Technology
RSC Advances | Year: 2015

Conducting polyaniline (PANi)-graphene (G) free standing, hybrid films were obtained by a solution intercalation method suitable for electromagnetic interference (EMI) shielding applications. The films were characterized structurally using Fourier transform infrared spectroscopy, micro-Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The electrical characterization was done using Hall measurement setup to estimate the dc electrical conductivity and establish the charge carrier type and mobility and investigate the possibility of using the hybrid films in other applications. The thermal stability of the films was investigated using thermo gravimetric analysis. The EMI shielding effectiveness (SE) of the composite films was tested over a broad microwave frequency range covering 4-12 GHz (C and X bands) by waveguide transmission line technique. The films exhibit very high values of reflected power (Pr) in the range of 85-90% in the C-band and 75-80% in the X-band, respectively. A maximum total shielding effectiveness value of SET ∼ 42 dB could be observed in the frequency range of 4-8 GHz and SET ∼ 32 dB could be observed in the frequency range of 8-12 GHz, corresponding to more than 99.99% microwave attenuation in both the C and X bands. In the entire frequency range of analysis, contributions from reflection to the total EMI SE is very high compared to that of absorption. The results suggest that the hybrid film may be used as effective, lightweight and flexible, reflection dominated EMI shielding material in a broad range of electromagnetic spectrum. This journal is © The Royal Society of Chemistry. Source


Sheela D.,PES Institute of Technology Bangalore South Campus | Mahadevan G.,Anna University | Mahadevan G.,University
International Review on Computers and Software | Year: 2013

Sensor networks are dense wireless networks of small, low-cost sensors, which collect and disseminate environmental data. Wireless Sensor Networks have many characteristics that make them very vulnerable to malicious attacks. Lot of security algorithms were implemented to provide security system of WSN. Still it is an open area to research. Because, It is difficult to perform continuous surveillance after network deployment since WSN is usually deployed in hostile areas without any fixed infrastructure. Recently, mobile agents have been proposed for efficient data dissemination in sensor networks. In the traditional client/server-based computing architecture, data at multiple sources are transferred to a destination; whereas in the mobileagent based computing paradigm, a task specific executable code traverses the relevant sources to gather data. Mobile agents can be used to greatly reduce the communication cost, especially over low bandwidth links, by moving the processing function to the data rather than bringing the data to a central processor. Here a mobile agent paradigm is proposed for implementing security system against hello flooding, Path based Denial of Service attack and traffic analysis. © 2013 Praise Worthy Prize S.r.l. - All rights reserved. Source


Faisal M.,PES Institute of Technology Bangalore South Campus | Khasim S.,PES Institute of Technology Bangalore South Campus | Khasim S.,University of Tabuk
AIP Conference Proceedings | Year: 2013

This work highlights the microwave absorption and electromagnetic interference (EMI) shielding properties of synthesized polyaniline (PAni)-antimony oxide (Sb2O3) composites in the 8-12 GHz (X-band) range. These composites showed absorption dominated EMI shielding effectiveness (EMI SEA) of -34 to -40 dB (> 99 % attenuation), indicating their shielding potential throughout the X-band. Our analyses reveal that the Sb2O3 particles in PAni matrix have key impact in determining the microwave absorption properties of the composites. © 2013 American Institute of Physics. Source


Faisal M.,PES Institute of Technology Bangalore South Campus | Khasim S.,PES Institute of Technology Bangalore South Campus | Khasim S.,University of Tabuk
Bulletin of the Korean Chemical Society | Year: 2013

Polyaniline-yttrium trioxide (PAni-Y2O3) composites were synthesized by the in-situ polymerization of aniline in the presence of Y2O3. The composite formation and structural changes in these composites were investigated by X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The direct current (DC) electrical conductivity of the order of 0.51 × 10-2 S cm-1 - 0.283 S cm-1 in the temperature range 300 K-473 K indicates semiconducting behavior of the composites. Room temperature AC conductivity and dielectric response of the composites were studied in the frequency range of 10 Hz to 1 MHz. The variation of AC conductivity with frequency obeyed the power law, which decreased with increasing weight percentage (wt %) of Y2O3. Studies on dielectric properties shows the relaxation contribution coupled by electrode polarization effect. The dielectric constant and dielectric loss in these composites depend on the content of Y2O3 with a percolation threshold at 20 wt % of Y2O3 in PAni. Electromagnetic interference shielding effectiveness (EMI SE) of the composites in the frequency range 100 Hz to 2 GHz was in the practically useful range of -12.2 dB to -17.2 dB. The observed electrical and shielding properties were attributed to the interaction of Y2O3 particles with the PAni molecular chains. Source


Faisal M.,PES Institute of Technology Bangalore South Campus | Khasim S.,PES Institute of Technology Bangalore South Campus
E-Polymers | Year: 2014

This article highlights the microwave absorption and dielectric attributes of synthesized polyaniline (PAni)-yttrium trioxide (Y2O3) composites. Temperaturedependent conductivity measurements were carried out in the temperature range of 300-473 K, which indicates the presence of hopping conduction. The PAni-Y2O3 composites showed semiconductor behavior with the exponential variation of inverse temperature dependence of electrical conductivity. Microwave measurements were carried out in the X-band (8-12 GHz) frequency; the composites exhibit absorption-dominated shielding effectiveness (SEA) in the range -33 to -35 dB ( > 99% microwave attenuation) and minimum electromagnetic reflection. The ε′ and ε″ values of the composites are in the range of 81.5-97.5 and 80-118.5, respectively. The PAni-Y2O3 composites showed significant improvement in microwave SE and complex permittivity of the composites, indicating the influence of Y2O3 in PAni. Source

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