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Prasad M.N.M.,Andhra University | Hussain M.A.,Andhra University | Sastry C.V.,Regency Institute of Technology
Journal of Theoretical and Applied Information Technology | Year: 2014

NTRU Labs have proposed a scheme for secure transmission using ring of truncated polynomials in Zq(x) / (xn -1). We have proved in this paper that a pre-processing the data to be transmitted greatly decreases the time of transmission. We have used a matrix version of NTRU Cryptosystems. © 2005 - 2014 JATIT & LLS. All rights reserved.

Uma Maheswara Rao C.,Andhra University | Bala Murali Krishna V.,Regency Institute of Technology | Laxmi Soundarya A.,JNTUH College of Engineering | Krishna Kumari N.,JNTUH College of Engineering
International Journal of Control Theory and Applications | Year: 2015

This paper proposes to describe Field oriented control (FOC) of Permanent Magnet Synchronous motor (PMSM) using Model Reference Adaptive control System (MRAS) speed observer for sensorless control of drive. The objective of the proposed sensorless control is to improve the speed control performance and robustness of PMSM drive under load variations. In this work, the conventionally used PI controller in adaption mechanism of the MRAS observer is replaced by a FLC. The improvement in speed response during load variations is shown by comparative study between conventional PI and fuzzy PI. The effectiveness and validity of the proposed control approach is verified by simulation results. © International Sciences Press, India.

Lakshmi C.S.,Regency Institute of Technology | Sridhar C.S.L.N.,Vignana Bharathi Institute of Technology | Govindraj G.,Pondicherry University | Bangarraju S.,Andhra University | Potukuchi D.M.,Jawaharlal Nehru Technological University Kakinada
Journal of Materials Science | Year: 2016

Structural, morphological, magnetic, and dielectric investigations are carried out in Nb-doped (viz., for x equal to 0.0–0.4 by wt%) nanocrystalline Ni–Zn ferrites synthesized by hydrothermal method. XRD, IR studies infer the growth of nano structures and Fe2O3 phase. Nb ions segregate at grain boundaries. Crystallite size (D) varies from 62 to 18 nm with x. FTIR absorption exhibits split at higher x. Saturation magnetization witnesses an overall decrease with x. Trends of Ms(x) are explained by nature of dopant, preferential replacement, surface canting (Y–K angles) and lattice contraction. Variations of coercive field (Hc) and D infer single-domain to multi-domain morphological transformation. Occurrence of superparamagnetism (SPM) is predicted for zeroed values of Hcand for a critical concentration xcrit equal to 0.321. Enhanced Nb5+–Fe2+ binding with dopant (x up to 0.2) results for decrease in dielectric constant (Formula presented.), loss factor tanδ and increase in resistivity ρ. Lowered ac conductivity is attributed to blockade of path by Nb5+ ions in the vicinity of B-sites. Relatively higher ρ (~108 Ω cm) and lower loss (tanδ ~10−2–10−3) evinced for 10 kHz. Enhanced core loss is realized with x manifested as lowered Hc and tanδ to usher their utility in high-frequency applications. © 2016 Springer Science+Business Media New York

Santhi Lakshmi M.V.,JNTUK | Sai Babu Ch.,JNTUK | Satya Prasad G.R.K.D.,Regency Institute of Technology
IET Conference Publications | Year: 2012

The limited reserves of fossil fuels and global environmental concerns over their use for electric power generation had augmented the attention in the exploitation of renewable energy resources. In particular, rapid advances in wind-turbine generator and photovoltaic technologies have brought opportunities for the utilization of wind and solar resources for electric power generation world-wide. Moreover, the economic aspects of these technologies are now adequately hopeful to also justify their use in small-scale stand-alone applications for residential use. If the development of a computer-based approach for evaluating the general performance of standalone hybrid wind-PV generating systems are analyzed and their results are reached to the common consumer with the economical analysis so that these systems can made more popular. In this paper a simulation approach has been suggested for designing Off-grid homes. Hourly average of wind speed/solar radiation data from the site is taken for the generating unit and the anticipated load data are used to predict the general performance of the generating system. The excess wind/solar-generated power, when available, is used to supply the power to the grid. Simulation studies were carried out using HOMER software. Simulation results will be given for performance evaluation of a standalone hybrid wind-PV generating unit for a residential house assumed to be located in a remote area which is analyzed as connected with grid and without connected to grid. Finally, the results obtained and methods are suggested to enhance the performance of the proposed model.

Prasad D.,Srk Government Arts College | Panda S.S.,Regency Institute of Technology | Subrahmanyam S.V.,Koneru Lakshmaiah College of Engineering
Lecture Notes in Mechanical Engineering | Year: 2014

This paper presents theoretical investigations of the rheological effects of lubricant on the performance of the Journal bearing system under steady state condition including squeezing. Runga Kutta Fehlberg method is employed to solve the Reynolds and the energy equations governing the flow of power law fluids simultaneously. Those equations are coupled due to the consistency which is a function of pressure and temperature both. The results show that this simple innovative model can reasonably calculate delta profile and hence the pressure and the temperature. The obtained results that the pressure and the temperature both increase with the power law flow index n and decrease with the increase of the squeezing parameter q. These results are found to be similar to the results available in the literature. © Springer India 2014.

Prasad D.,Srk Government Arts College | Subrahmanyam S.V.,Koneru Lakshmaiah College of Engineering | Panda S.S.,Regency Institute of Technology
Tribology in Industry | Year: 2014

Hydrodynamically heavily loaded rigid cylindrical rollers, lubricated by a thin compressible fluid film, are investigated for normal squeezing motion and cavitations. The lubricant is assumed to follow the non-Newtonian power-law fluid model where consistency and density of the lubricant vary with one dimensional pressure and temperature. The modified Reynolds pressure equation and thermal energy equation are derived and solved simultaneously by R-K Fehlberg method. Secant method is also applied in order to enforce the boundary condition at the outlet. It is observed that temperature has significant effects on consistency and density both. It is also to be noted that compressibility effect is even more significant when squeezing is taken into account. © 2014 Published by Faculty of Engineering.

Prasad D.V.S.S.S.V.,Regency Institute of Technology | Krishna A.G.,Jawaharlal Nehru Technological University Kakinada
International Journal of Advanced Manufacturing Technology | Year: 2015

Wire electrical discharge machining (WEDM) is a commonly used process in manufacturing industries to machine electrically conductive materials with complex shapes and varying hardness. The performance of any machining process is based on right selection of input variables. The selection of optimal parameters in WEDM is a difficult task as it is a highly stochastic process in nature. The present work deals with the development of empirical relationships for the output responses of kerf (cutting width) and wire wear ratio considering pulse-on time, pulse-off time, wire tension, dielectric flow rate, and wire feed as the input variables. Response surface methodology is used to find the quantitative relations. Subsequently, the developed mathematical models are used for optimization. A recently developed global optimization technique, harmony search algorithm, is applied to find the optimal set of input control variables. © 2014, Springer-Verlag London.

Prasad M.S.R.S.,Koneru Lakshmaiah College of Engineering | Meerja K.A.,Koneru Lakshmaiah College of Engineering | Sastry C.V.,Regency Institute of Technology
International Journal of Applied Engineering Research | Year: 2014

Transmission of images securely is of paramount importance in all banking transactions as well as in medical emergencies. Several Cryptographic schemes exist in the literature and the NTRU scheme, proposed by Hoffstein and Piper based on the Ring of Integer Polynomials has been thoroughly studied. However the polynomial Inversion using Modulo-Arithmetic is the bottle-neck in all the schemes based on Modular Lattices. Recently a scheme known as LWE (Learning With Errors) has been proposed for encryption of data whose security is based on the impossibility of distinguishing a solution to a set of equations, from the solutions with slightly perturbed set where the errors or perturbations are distributed normally. We have improved on the previously proposed algorithm by pre-processing the data before encryption and showed that the time of encryption and decryption can be considerably reduced. © Research India Publications.

Lakshmi C.S.,Regency Institute of Technology | Sridhar C.S.L.N.,Vignana Bharathi Institute of Technology | Govindraj G.,Pondicherry University | Bangarraju S.,Andhra University | Potukuchi D.M.,Jawaharlal Nehru Technological University Kakinada
Physica B: Condensed Matter | Year: 2015

Nanocrystalline Ni-Zn-Sb ferrites synthesized by hydrothermal method are reported. Influence of Sb5+ ions on structural, magnetic and dielectric properties of ferrites is studied. Phase identification, lattice parameter and crystallite size studies are carried out using by X-ray diffraction (XRD). Addition of dopant resulted for decrease in lattice parameter. Crystallite size gets reduced from 62 nm to 38 nm with doping of Antimony. Crystallite size and porosity exhibit similar trends with doping. Morphological study is carried out by Field Emission Scanning Electron Microscopy (FESEM). Strong FTIR absorption bands at 400-600 cm-1 confirm the formation of ferrite structure. Increase of porosity is attributed to the grain size. Doping with Antimony results for decrease in saturation magnetization and increase in coercivity. An initial increase of saturation magnetization for x=0.1 is attributed to the unusually high density. Reversed trend of coercivity with crystallite size are observed. Higher value of dielectric constant ε′(ω) is attributed to the formation of excess of Fe2+ ions caused by aliovalent doping of Sb5+ ions. Variation of dielectric constant infers hopping type of conductivity mechanism. The dielectric loss factor tanδ attains lower values of ~10-2. High ac resistivity ρ(ω) of 108 ω cm is witnessed for antimony doped ferrites. Higher saturation magnetization and enhanced dielectric response directs for a possible utility as microwave oscillators and switches. © 2014 Elsevier B.V. All rights reserved.

Sridhar C.S.L.N.,Vignana Bharathi Institute of Technology | Lakshmi C.S.,Regency Institute of Technology | Govindraj G.,Pondicherry University | Bangarraju S.,Andhra University | And 2 more authors.
Journal of Physics and Chemistry of Solids | Year: 2016

Nano-phased doped Mn-Zn ferrites, viz., Mn0.5-x/2Zn0.5-x/2SbXFe2O4 for x=0 to 0.3 (in steps of 0.05) prepared by hydrothermal method are characterized by X-ray diffraction, Infrared and scanning electron microscopy. XRD and SEM infer the growth of nano-crystalline cubic and hematite (α-Fe2O3) phase structures. IR reveals the ferrite phase abundance and metal ion replacement with dopant. Decreasing trend of lattice constant with dopant reflects the preferential replacement of Fe3+ions by Sb5+ion. Doping is found to cause for the decrease (i.e., 46-14 nm) of grain size. An overall trend of decreasing saturation magnetization is observed with doping. Low magnetization is attributed to the diamagnetic nature of dopant, abundance of hematite (α-Fe2O3) phase, non-stoichiometry and low temperature (800 °C) sintering conditions. Increasing Yafet-Kittel angle reflects surface spin canting to pronounce lower Ms. Lower coercivity is observed for x≤0.1, while a large Hc results for higher concentrations. High ac resistivity (~106 ohm-cm) and low dielectric loss factor (tan δ~10-2-10-3) are witnessed. Resistivity is explained on the base of a transformation in the Metal Cation-to-Oxide anion bond configuration and blockade of conductivity path. Retarded hopping (between adjacent B-sites) of carriers across the grain boundaries is addressed. Relatively higher resistivity and low dielectric loss in Sbdoped Mn-Zn ferrite systems pronounce their utility in high frequency applications. © 2016 Elsevier Ltd.

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