Faculty Publications
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Item Composition of location based services in decentralized registry based architecture(Springer Verlag, 2013) Kumari, K.; D'Souza, M.; Ananthanarayana, V.S.The massive growth of wireless communications and mobile database technologies has transformed the cell phone from being a mere portable phone to becoming an essential medium for contact, information and entertain-ment. A new trend has been evolved in mobile services which are used to provide user location based experience. It has opened a golden door for location based services. Location-based services denote services provided to mobile users according to their geographic location. There are two registry based archi-tecture, one is centralized and other is decentralized. In centralized architecture, first location of the user is determined and then central registry is looked up for requested services. In decentralized architecture, each of the location is sup-posed to be associated with a local registry which would be looked up for the requested services. But decentralized architecture is not able to give the information about services available in location other than user’s present location. There are a number of real world problems, which gives emphasis on the need of advance knowledge of availability of services present in other location and fulfillment of the total goal. Hence, in order to fulfill the above need, a methodology has been proposed in this paper. It minimizes the user involvement to a great extent in order to avail any online service. In this, composition plan would be created a priory to execution of services and selection of services would be based on QoS parameters in order to minimize the total cost. © Springer-Verlag Berlin Heidelberg 2013.Item Complex impedance spectroscopy properties of Fe3BO6 nanocrystallites prepared by combustion method(Elsevier Ltd, 2019) Kumari, K.; Ramteke, R.; Rahman, M.R.In this investigation, we report a part of our work on Impedance spectroscopy of Fe3BO6 nanoceramics prepared by a selfcombustion of a solid precursor mixture of 60Fe2O3-40B2O3 using camphor as a fuel in ambient air. A single phase compound Fe3BO6 of an orthorhombic crystal structure with Pnma space group and average crystallites size D = 42 nm is analyzed from the X-ray diffractogram. The Z?-value decreases with a shift in the peak frequency towards the higher side with rise in temperature arises possibly due to the presence of dipolar response in the material, which is in good agreement with the observation of complex impedance data. Temperature dependent impedance describes Fe3BO6 to be an ionic conductor; with activation energy (Ea) value0.73 eV. The Ea-values so obtained for the dielectric relaxation from the tp-values suggests a conduction mechanism involving the polaron hopping. © 2019 Elsevier Ltd. All rights reserved.Item Magnetic and dielectric properties of Fe3BO6 nanoplates prepared through self-combustion method(World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2017) Kumari, K.In the present investigation, a facile synthesis method is explored involving a self-combustion of a solid precursor mixture of iron oxide Fe2O3 and boric acid (H3BO3) using camphor (C10H16O) as fuel in ambient air in order to form a single phase Fe3BO6 crystallites. X-ray diffraction (XRD), Field emission electron microscopy (FESEM), magnetic, and dielectric properties of as prepared sample are studied. From XRD pattern, a single phase compound is observed with an orthorhombic crystal structure (Pnma space group), with average crystallite size of 42 nm. A reasonably uniform size distribution of the plates and self-assemblies is retained in the sample. A magnetic transition is observed in dielectric permittivity (at ~445 K) and power loss (at ~435 K) when plotted against temperature. Aweak peak occurs near 330K due to the charge reordering in the sample. For temperatures above the transition temperature, a sharp increase of the dielectric loss is observed which occurs due to the presence of thermally activated charge carriers. A canted antiferromagnetic Fe3+ ordering in a Fe3BO6 lattice with a localized charge surface layer is an apparent source of exhibiting a ferroelectric feature in this unique example of a centrosymmetric compound. An induced spin current over the Fe sites thus could give rise to a polarization hysteresis loop. Due to the presence of both ferromagnetic as well as polarization ordering, Fe3BO6 behaves like a single phase multiferroic ceramics. © The Author(s).Item Effect of temperature on magnetic and impedance properties of Fe3BO6 of nanotubular structure with a bonded B2O3 surface layer(American Institute of Physics Inc. subs@aip.org, 2018) Kumari, K.; Ram, S.; Kotnala, R.K.In this investigation, we explore a facile synthesis of Fe3BO6 in the form of small crystallites in the specific shape of nanotubes crystallized from a supercooled liquid Fe2O3-B2O3 precursor. This study includes high resolution transmission electron microscopy (HRTEM) images, magnetic, optical, and impedance properties of the sample. HRTEM images reveal small tubes of Fe3BO6 of 20 nm diameter. A well resolved hysteresis loop appears at 5 K in which the magnetization does not saturate even up to as high field as 50 kOe. It means that the Fe3BO6 nanotubes behave as highly antiferromagnetic in nature in which the surface spins do not align along the field so easily. The temperature dependent impedance describes an ionic Fe3BO6 conductor with a reasonably small activation energy Ea ? 0.33 eV. Impedance formalism in terms of a Cole-Cole plot shows a deviation from an ideal Debye-like behavior. We have also reported that electronic absorption spectra are over a spectral range 200-800 nm of wavelengths in order to find out how a bonded surface layer present on the Fe3BO6 crystallites tunes the 3d ? 3d electronic transitions in Fe3+ ions. © 2018 Author(s).Item Structural, vibrational and surface analysis of Fe3BO6 nanoplates synthesized by combustion method(Elsevier B.V., 2018) Kumari, K.In the present investigation, a simple synthesis method is explored involving a self-combustion of a solid precursor mixture of iron oxide (Fe2O3) and boric acid (H3BO3) using camphor (C10H16O) as fuel in microwave oven in order to form a single phase Fe3BO6 crystallites. An as-prepared ceramic powder in this way after combustion of a precursor, which contained a lot of residual carbon left after the combustion, was reheated at 400 °C to burn it out as oxide in a reaction with air. This is a very simple and fast method to form a phase pure compound from usual metal salts with functional properties. The size and morphology of the Fe3BO6 crystallites has been characterized in terms of X-ray diffraction (XRD) pattern in correlation to the field emission scanning electron microscopy (FESEM) image. A single phase compound Fe3BO6 of an orthorhombic crystal structure with Pnma space group and average crystallites size D = 46 nm is analyzed from the XRD pattern. IR/Raman and X-ray photoelectron spectroscopy (XPS) spectra studied for the Fe3BO6 samples in this investigation elucidate how the density of states of the phonons and valence electrons confine in small crystallites. The XPS bands in Fe3+, B3+ and O2? species and IR/Raman bands in the oxygen polygons confer the results of forming Fe3BO6 with a bonded surface layer. © 2018 Elsevier B.V.Item Sensitivity Study of Nanocrystalline Fe3BO6 Sensor for Methane Gas Detection(Institute of Electrical and Electronics Engineers Inc., 2018) Kumari, K.; Ram, S.The iron borate Fe3BO6 with functionalized properties in a nanostructure is an important material useful for electrodes, gas sensors, and biological probes. In this paper, we studied the X-ray diffraction pattern, field-emission electron microscopy, and methane (CH4) gas sensing properties of synthesized Fe3BO6 nanocrystallites in a shape of nanoplates and nanobars from an iron borate glass 40Fe2O3-60B2O3 by annealing it in microwave for 15 min at 823 and 1023 K, respectively, in air. The temperature dependent sensitivity for CH4 (1000 ppm) illustrates a maximum value of 43% at an operating temperature 525 K for the 1023 K annealed sample. The sensitivity is found to be varied from 9% to 39% when the CH4 gas concentration is increased from 50 to 1000 ppm. Thus, the sample has a reasonably good sensitivity for methane. Furthermore, the sensor exhibits fast response (1 min) and a good recovery time (1.6 min) as compared with other oxide materials. © 2001-2012 IEEE.Item Phase analysis, FTIR/Raman, and optical properties of Fe3BO6 nanocrystallites prepared by glass route at moderate temperature in ambient air(Elsevier B.V., 2018) Kumari, K.In this paper, a facile synthesis method is explored from a supercooled liquid Fe2O3–B2O3 precursor using microwave furnace in order to obtain a single phase Fe3BO6 compound. Study includes X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), high resolution transmission electron microscopy (HRTEM) images, FTIR/Raman and optical property of sample. The crystal structure and size of the Fe3BO6 crystallites have been characterized in terms of XRD pattern in correlation to the FESEM/HRTEM images. A single phase compound Fe3BO6 of an orthorhombic crystal structure with Pnma space group and average crystallites size D = 49 nm is analyzed from the XRD pattern. IR and Raman bands in the oxygen polygons confer the results of forming Fe3BO6 with a bonded surface layer. UV–visible absorption spectrum over a spectral range 200–800 nm of wavelengths reveals two high-energy bands 222 and 277 nm possibly represent a ligand to metal charge transfer transition while one broad and relatively weak band appears in the visible region at 400 nm ascribed to a ligand field transition 6A1 ? 4T1 of the 3 d5 electrons in the Fe3+ ions occupied. This compound also endures good optical properties in the visible and ultraviolet regions that can be combined to magnetic and other properties useful for developing multifunctional features for possible applications. © 2018Item Thermal stability and spectroscopic properties of Fe 3 BO 6 of small crystallites with a bonded carbon surface layer(Elsevier Ltd, 2019) Kumari, K.A well-known canted antiferromagnetic Fe 3 BO 6 with functionalized properties is an important material useful for light energy carrier, electrodes, gas sensors, and biological probes. In this investigation, a facile synthesis is explored in order to obtain Fe 3 BO 6 of small crystallites in a specific shape of nanoplates by self-combustion method. To access (i) whether Fe 3 BO 6 is formed at the as-prepared stage and (ii) how it stands stable with a residual carbon surface layer, thermal gravimetric (TG) analysis has been carried out by heating 10–20 mg powder (as-prepared) at a typical 10 K/min heating rate over 300–1100 K under air or argon atmosphere. The electronic absorption, infrared (IR) and Raman spectra studied for the Fe 3 BO 6 sample in this investigation elucidate how the density of states of the phonons and valence electrons confine in small crystallites. IR and Raman bands in the oxygen polygons also confer the results of forming Fe 3 BO 6 with a bonded surface carbon layer. A stable bonded surface layer supports thermal stability of small crystallites and it affects other useful functional properties. © 2018 Elsevier B.V.Item Emission from open burning of municipal solid waste in India(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) Kumari, K.; Kumar, S.; Rajagopal, V.; Khare, A.; Kumar, R.Open burning of Municipal Solid Waste (MSW) is a potential non-point source of emission, which causes greater concern especially in developing countries such as India. Lack of awareness about environmental impact of open burning, and ignorance of the fact, i.e. ‘Open burning is a source of emission of carcinogenic substances’ are major hindrances towards an appropriate municipal solid waste management system in India. The paper highlights the open burning of MSW practices in India, and the current and projected emission of 10 major pollutants (dioxin, furans, particulate matter, carbon monoxide, sulphur oxides, nitrogen oxides, benzene, toluene, ethyl benzene and 1-hexene) emitted due to the open burning of MSW. Waste to Energy potential of MSW was also estimated adopting effective biological and thermal techniques. Statistical techniques were applied to analyse the data and current and projected emission of various pollutants were estimated. Data pertaining to population, MSW generation and its collection efficiency were compiled for 29 States and 7 Union Territories. Thereafter, emission of 10 pollutants was measured following methodology prescribed in Intergovernmental Panel on Climate Change guideline for National Greenhouse Gas Inventories, 2006. The study revealed that people living in Metropolitan cities are more affected by emissions from open burning. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.Item Synthesis and characterization of zinc oxide incorporated iron borate glass-ceramic(Elsevier Ltd, 2019) Ramteke, R.; Kumari, K.; Bhattacharya, S.; Rahman, M.R.Here, zinc oxide (ZnO) incorporated iron borate (Fe3BO6) glass-ceramics have been synthesized using the traditional melt-quenching technique, and the role of ZnO has been investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveals that the prepared samples have a single crystalline phase and crystalline nanostructures, respectively. The orthorhombic crystal structure has been retained without the formation of a new crystalline phase. The addition of ZnO is found to distort the Fe3BO6 lattice by substituting Zn2+ in the Fe3+ sites, with the formation of ZnO6 structural units as revealed by Fourier transform infrared spectroscopy (FTIR). FTIR and Raman spectroscopy conducted to study the structure of glass-ceramic, have also revealed the formation of other structural units like ZnO4, BO3, BO4, and FeO6 in the system. Surface analysis conducted by X-ray photoelectron spectroscopy (XPS) reveals that the addition of ZnO diminishes the formation of surface B2O3 layer which forms over the Fe3BO6 phase in the Fe3BO6 iron borate glass-ceramic system. ZnO addition has also shown a remarkable difference in the volume of the crystallization in the system, thereby paving the way for controlled crystallization in the iron borate glass-ceramic system. The controlled crystallization was achieved through additive content, retaining the iron borate (Fe3BO6) glass-ceramic system without the evolution of any secondary phases even with large additive concentrations up to 10 mol%. © 2019 Elsevier B.V.