Faculty Publications
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Item Trust models in cloud: A survey on pros and cons(Springer Verlag service@springer.de, 2015) Divakarla, U.; Chandra Sekaran, K.Cloud is the recent emerging technology in all aspects. The basic concern with the usage of this cloud technology is security. Security poses a major drawback with data storage, resource utilization, virtualization, etc. In the highly competitive environment the assurances are insufficient for the customers to identify the trust worthy cloud service providers. In a nut shell all the entities in cloud and cloud computing environment should be trusted by each other and the entities that have communication should be trusted by each other. This paper throws light on different Trust Models developed and their drawback with respect to resource security. A strong Trust Model is recommended to enhance the security of the resources in Cloud. © Springer International Publishing Switzerland 2015.Item Ranking and comparison of draw solutes in a forward osmosis process(Techno Press technop2@chollian.net, 2017) Girijan, G.; Thalla, A.K.Forward osmosis (FO) is an emerging technology which can possibly make the desalination process more cost and energy efficient. One of the major factors impeding its growth is the lack of an appropriate draw solute. The present study deals with the identification of potential draw solutes, and rank them. The comparison was carried out among ten draw solutes on the basis of four main parameters namely; water flux, reverse salt diffusion, flux recovery and cost. Each draw solute was given three 24 hour runs; corresponding to three different concentrations; and their flux and reverse salt diffusion values were calculated. A fresh membrane was used every time except for the fourth time which was the flux recovery experiment conducted for the lowest concentration and the change of flux and reverse salt diffusion values from the initial run was noted. The organic solutes inspected were urea and tartaric acid which showed appreciable values in other parameters viz. reverse salt diffusion, flux recovery and cost although they generated a lower flux. They ranked 5th and 8th respectively. All the experimented draw solutes were ranked based on their values corresponding to each of the four main parameters chosen for comparison and Ammonium sulfate was found to be the best draw solute. © 2017 Techno-Press, Ltd.Item Effective integration of reliable routing mechanism and energy efficient node placement technique for low power IoT networks(IGI Global cust@igi-global.com, 2017) Sarwesh, P.; Shet, N.S.V.; Chandrasekaran, K.Internet of Things (IoT) is the emerging technology that links physical devices (sensor devices) with cyber systems and allows global sharing of information. In IoT applications, devices are operated by battery power and low power radio links, which are constrained by energy. In this paper, node placement technique and routing mechanism are effectively integrated in single network architecture to prolong the lifetime of IoT network. In proposed network architecture, sensor node and relay node are deployed, sensor nodes are responsible for collecting the environmental data and relay nodes are responsible for data aggregation and path computation. In node placement technique, densities of relay nodes are varied based on traffic area, to prevent energy hole problem. In routing technique, energy efficient and reliable path computation is done to reduce number of re transmissions. To adopt IoT scenario, we included IEEE 802.15.4 PHY/MAC radio and IPv6 packet structure in proposed network architecture. Proposed work result shows, proposed architecture prolongs network lifetime. © © 2017, IGI Global.Item High-speed and reliable Underwater Wireless Optical Communication system using Multiple-Input Multiple-Output and channel coding techniques for IoUT applications(Elsevier B.V., 2020) Naik, P.N.; Acharya Udupi, S.; Krishnan, P.In this paper, we investigate the performance of an Underwater Wireless Optical Communication (UWOC) system employing on–off keying modulation at a data-rate of 500 Mbps over a link-range of 30 m. Transmit/receive diversity schemes, namely Multiple-Input to Single-Output (MISO), Single-Input to Multiple-Output (SIMO) and Multiple-Input to Multiple-Output (MIMO) techniques with and without RS-coding have been employed to mitigate the effects of weak oceanic turbulence and beam attenuation. The novel closed-form analytical Bit Error Rate (BER) expressions of Single-Input to Single-Output (SISO), SIMO, MISO and MIMO links for un-coded and RS-coded cases have been computed using the hyperbolic tangent distribution and validated with Monte-Carlo simulation results. The obtained BER results show that the use of (63,51) RS-coded 4 × 5 MIMO UWOC system offers at-least 35 dB of transmit power gain compared with the un-coded SISO UWOC system at a BER of 10?5. Emerging technologies like the fifth-generation (5G) networks and the Internet of Underwater Things (IoUT) will have a high impact on UWOC as these systems require a high degree of information integrity, high data rates and energy efficiency when employed in conjunction with data transfer between underwater vehicles and objects. The proposed RS-coded MIMO UWOC system offers high reliability and power efficiency and it has the potential to be gainfully employed in IoUT applications. © 2020 Elsevier B.V.Item Study of devolatilization during chemical looping combustion of large coal and biomass particles(Elsevier B.V., 2020) Pragadeesh, K.S.; Iyyaswami, I.; Ruben Sudhakar, D.R.Chemical Looping Combustion (CLC) is one of the emerging technologies for carbon capture, with less energy penalty. The present way of using pulverized coals in a fluidized bed (FB)-CLC have limitations like loss of unconverted char and gaseous combustibles, which could be mitigated by use of coarser fuel particles. Devolatilization time is a critical input for the effective design of FB-CLC systems, primarily when large fuel particles are used. The present study investigates the devolatilization time and the char yield of three coals of two shapes, namely, two high ash Indian coals and a low ash Indonesian coal and a wood (Casuarina equisetifolia) in the size range of +8–25 mm, at different fuel reactor temperatures (800–950 °C) of a hematite based CLC unit. The devolatilization times of single fuel particles during CLC are determined using a visual method called ‘Color Indistinction Method’. Indonesian coal has the longest devolatilization time among the fuels, and biomass has the least. Increasing the bed temperature enhances the rate of volatile release, whereas this effect is less pronounced in larger particles. Devolatilization of Indonesian coal is found to be strongly influenced by the changes in operating conditions. With the decrease in sphericity, a maximum of 56% reduction in devolatilization time is observed for the +20–25 mm slender particles of Indonesian coals when compared to the near-round particles. The maximum average char yields at the end of the devolatilization phase for coal and biomass are about 55–76% and 16% respectively. Char yield in coal particles increases with an increase in particle size, whereas biomass particles show relatively consistent yield across all experimental conditions. Increase in bed temperature reduces the char yields of coal up to 12% and in biomass up to 30%. High volatile Indian coal is the most influenced fuel by the changes in fuels shape. A correlation for determining devolatilization time under CLC environment is presented, and it successfully fits most of the experimental values within ±20% deviation for coals (R2 = 0.95) and within ±15% deviation for biomass (R2 = 0.97). © 2020 Energy InstituteItem Bit error rate analysis of polarization shift keying based free space optical link over different weather conditions for inter unmanned aerial vehicles communications(Springer, 2021) Nallagonda, V.; Krishnan, P.The increasing availability of unmanned aerial vehicles (UAVs) is an exciting part of future emerging technology with advanced scientific and industrial interests. Free space optical (FSO) communications’ ability to offer very high data rates and the mobility of unmanned aerial vehicle (UAV) flying platforms make the delivery of Fifth-Generation (5G) wireless networking services appealing to FSO-UAV-based solutions. UAVs play a greater role in end-to-end delivery in next- generation wireless networking systems, serving as a base station, capacity enhancement, high data access, and other disaster management systems. To establish a link between unmanned aerial vehicles and ground stations, FSO can be applied. But, the different weather conditions liken rain, fog effects on the performance of the FSO link, contributing to the loss of the signal. In this paper, we proposed polarization shift keying (POLSK) modulated FSO link based UAV–UAV communication system for 6G beyond applications. We examine the effect of different weather conditions such as rain, fog on the bit error rate (BER) performance of the proposed system. Novel closed-form expressions for UAV–UAV based FSO propagation channel are derived, and BER performance is investigated under different weather conditions. Fog and rain are the main limiting factors mitigated in this paper by suitable mitigation techniques by increasing receiver field of view. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Bit error rate analysis of ground-to-high altitude platform free-space optical communications using coded polarization shift keying in various weather conditions(Springer, 2022) Nallagonda, V.; Krishnan, P.High altitude platforms (HAPs) aided free-space optical (FSO) communication, a future emerging technology for next-generation communication systems. HAP aided FSO communication systems, contributing significantly to data hunger applications. Weather conditions, angle of arrival fluctuations, blockages, and pointing error loss due to the HAP’s hovering state are some of the limitations to establishing an efficient link. In this paper, we proposed for the first time a Ground-to-HAP FSO communication system based on polarization shift keying to improve performance under hovering fluctuations. We also improved the proposed system’s performance by employing BCH and repetition coding schemes. The proposed system’s average bit error rate performance is expressed in closed form, and the results are analysed under various weather conditions such as rain (light and heavy) and fog (light and moderate). The results for coded and uncoded cases are compared. The achieved coding gain is 28.5 dB. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.