Suresh Kumar N.,Naval Physical and Oceanographic Laboratory |
Bhattacharya C.,Defense Institute of Advanced Technology
2012 Annual IEEE India Conference, INDICON 2012 | Year: 2012
In this paper, we have broadened the scope of Direction of Arrival (DoA) estimation using compressive sampling in free space to a shallow ocean scenario, considering the complexities that arise due to the formation of modes in shallow ocean, along with the use of acoustic vector sensor array. We use compressive sampling of the array elements, followed by compressive beamforming, which helps in greatly reducing the complexity of the front-end circuitry and the size of array correlation matrix that is used in DoA estimation in MUSIC/MVDR algorithms. Also, in shallow ocean, the plane-wave DoA estimators generally yield biased estimates, due to the multimode nature of acoustic propagation. To solve this problem, the normal mode based MUSIC (NM-MUSIC) method is modified to be used with AVS array and compressive beamforming. In this paper, we propose a method that takes a very small set of informative measurements from an AVS array deployed in a shallow ocean, that still allow us to estimate DoA's. Simulation results for the Pekeris model of the ocean show that resolution obtained using the compressed AVS array is similar to that obtained using a conventional AVS array in which larger number of sensors with higher snapshots are used. © 2012 IEEE.
Harikrishnan G.,Indian Institute of Technology Kharagpur |
Patro T.U.,Indian Institute of Technology Bombay |
Patro T.U.,Defense Institute of Advanced Technology |
Unni A.R.,Huntsman Polyurethanes |
Khakhar D.V.,Indian Institute of Technology Bombay
Soft Matter | Year: 2011
Remarkable evolutionary changes in cell morphology during reactive polymer nanocomposite foaming are observed by controlled foaming of suspensions of montmorillonite clay in the oligomeric polyurethane component. Delaminated nanoplatelets, when present as a networked cluster in suspensions, are shown to have very high efficiency in generating gas embryos for bubble nucleation. In the post-nucleation foaming period, clay nanoplatelets show an additional de-wetting behavior. The packing fraction of clay platelets in suspension and the consequent suspension rheology affect the final foam morphology. © 2011 The Royal Society of Chemistry.
Nene M.J.,Defense Institute of Advanced Technology |
Deodhar R.S.,Armament Research and Development Establishment |
Patnaik L.M.,Indian Institute of Science
IEEE Sensors Journal | Year: 2015
In this paper, sensing coverage by wireless camera-embedded sensor networks (WCSNs), a class of directional sensors is studied. The proposed work facilitates the autonomous tuning of orientation parameters and displacement of camera-sensor nodes in the bounded field of interest (FoI), where the network coverage in terms of every point in the FoI is important. The proposed work is first of its kind to study the problem of maximizing coverage of randomly deployed mobile WCSNs which exploits their mobility. We propose an algorithm uncovered region exploration algorithm (UREA-CS) that can be executed in centralized and distributed modes. Further, the work is extended for two special scenarios: 1) to suit autonomous combing operations after initial random WCSN deployments and 2) to improve the network coverage with occlusions in the FoI. The extensive simulation results show that the performance of UREA-CS is consistent, robust, and versatile to achieve maximum coverage, both in centralized and distributed modes. The centralized and distributed modes are further analyzed with respect to the computational and communicational overheads. © 2001-2012 IEEE.
Ghosh S.,University of Pune |
Patil S.,University of Pune |
Ahire M.,University of Pune |
Kitture R.,Fergusson College |
And 8 more authors.
Journal of Nanobiotechnology | Year: 2012
Background: Novel approaches for synthesis of gold nanoparticles (AuNPs) are of utmost importance owing to its immense applications in diverse fields including catalysis, optics, medical diagnostics and therapeutics. We report on synthesis of AuNPs using Gnidia glauca flower extract (GGFE), its detailed characterization and evaluation of its chemocatalytic potential.Results: Synthesis of AuNPs using GGFE was monitored by UV-Vis spectroscopy and was found to be rapid that completed within 20 min. The concentration of chloroauric acid and temperature was optimized to be 0.7 mM and 50°C respectively. Bioreduced nanoparticles varied in morphology from nanotriangles to nanohexagons majority being spherical. AuNPs were characterized employing transmission electron microscopy, high resolution transmission electron microscopy. Confirmation of elemental gold was carried out by elemental mapping in scanning transmission electron microscopic mode, energy dispersive spectroscopy and X-ray diffraction studies. Spherical particles of size ~10 nm were found in majority. However, particles of larger dimensions were in range between 50-150 nm. The bioreduced AuNPs exhibited remarkable catalytic properties in a reduction reaction of 4-nitrophenol to 4-aminophenol by NaBH4 in aqueous phase.Conclusion: The elaborate experimental evidences support that GGFE can provide an environmentally benign rapid route for synthesis of AuNPs that can be applied for various purposes. Biogenic AuNPs synthesized using GGFE exhibited excellent chemocatalytic potential. © 2012 Ghosh et al; licensee BioMed Central Ltd.
Arora S.,Govind Ballabh Pant University of Agriculture & Technology |
Sharma P.,Govind Ballabh Pant University of Agriculture & Technology |
Kumar S.,Govind Ballabh Pant University of Agriculture & Technology |
Nayan R.,Govind Ballabh Pant University of Agriculture & Technology |
And 2 more authors.
Plant Growth Regulation | Year: 2012
Experiments were carried out to determine the effect of Gold-nanoparticles on the growth profile and yield of Brassica juncea, under field conditions. Five different concentrations (0, 10, 25, 50 and 100 ppm) of Gold-nanoparticles were applied through foliar spray. Presence of Gold-nanoparticles in the leaf tissues was confirmed through atomic absorption spectroscopy. Various growth and yield related parameters, including plant height, stem diameter, number of branches, number of pods, seed yield etc. were positively affected by the nanoparticle treatment. Gold-nanoparticle treatment increased the number of leaves per plant; however the average leaf area was not affected. Optimal increase in seed yield was recorded at 10 ppm of Gold-nanoparticle treatment. Reducing as well as total sugar contents increased up to 25 ppm of Gold-nanoparticle treatment. Application of nanoparticles also improved the redox status of the treated plants. The results, for the first time, demonstrate successful use of Gold-nanoparticles in enhancing growth and yield of B. juncea, under actual field conditions and present a viable alternative to GM crops for ensuring food security. © 2011 Springer Science+Business Media B.V.