Sharad Dwivedi

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Papers by Sharad Dwivedi

Dynamics of curved domain walls in hard ferromagnets with nonlinear dissipative and inertial effects

Physica D: Nonlinear Phenomena

Domain wall dynamics in cubic magnetostrictive materials subject to Rashba effect and nonlinear dissipation

Zeitschrift für angewandte Mathematik und Physik

Domain wall motion in multiferroic nanostructures under the influence of spin-orbit torque and nonlinear dissipative effect

Mechanics of Advanced Materials and Structures

Special Issue of ICETETS 2014 -Held on 24-25 February

Graphical password, text password are authentication of users on websites because of its simplici... more Graphical password, text password are authentication of users on websites because of its simplicity and easy. User's passwords are easy to hack by using different malicious programs and threats. First, Users select easy to remember password because nowadays they using many accounts on different websites. To login to websites they need to remember all passwords. So users would choose easy to remember passwords, but these passwords are not safe. Reusing passwords across different websites may cause users to lose their information which is stored in websites once the password hacked or compromised by attacker. Second, hackers can install malicious software to get the passwords, when user typing their username and password into unknown public computers. In this paper, developing web based security analysis of one Time password authentication schemes using mobile application. A user authentication protocol which involves user's cell phone and short message service to prevent password stealing and reuse attacks. User's only need to remember a long term password for login on different websites.

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Curved domain walls in the ferromagnetic nanostructures with Rashba and nonlinear dissipative effects

Applied Mathematics and Computation, 2022

On the Dynamics of Transverse Domain Walls in Ferromagnetic Heterostructures with Nonlinear Dissipative Effects

Mathematical Modelling and Scientific Computing with Applications, 2020

This work delineates the investigation of static and dynamical behavior of transverse domain wall... more This work delineates the investigation of static and dynamical behavior of transverse domain walls in ferromagnetic heterostructure in which the thin ferromagnetic layer is sandwiched between a heavy metal and a metal oxide layers. We consider the metallic ferromagnet with high perpendicular magnetic anisotropy and exhibits structural inversion asymmetry. The presence of a strong inversion asymmetry in the ferromagnetic material leads to additional spin-orbit coupling torque terms into the dynamics qualitatively different from the standard spin-transfer torques. The evolution of magnetization inside the ferromagnetic layer is governed by the one-dimensional model of generalized Landau-Lifshitz-Gilbert-Slonczewski equation consisting of the standard spin transfer and spin-orbit coupling torque terms along with the nonlinear dissipation factors viz. viscous and dry-friction. Under this framework, first, we establish the static magnetization profile in the two faraway domains in the presence of transverse magnetic field once the electric and longitudinal magnetic fields are switched off. Then, by means of regular perturbation expansion method, we derive the zero order traveling wave solutions under the influence of small applied magnetic field and spin-polarized electric currents.

Benefits of Integrated Protection and Control System for MV / LV Generators for Reliable Operation in the Petroleum & Chemical Industry

This paper discusses Integrated Protection and Control solution for medium size generators (typic... more This paper discusses Integrated Protection and Control solution for medium size generators (typical machine size around 50MW) to be applied in petroleum and chemical industry utilizing modern generator protection and control devices. As with any continuous running process plant, the availability of power is of paramount importance and so is the case of having most reliable Protection & Control solution to protect these vital generators. Also discussed is the redundancy approach with overlapping protection zones / protections to increase the overall reliability, utilization of novel (enhanced) protection functionalities (earlier available only for large size machines) to further enhance the selectivity with functions such as Out-of-Step protection, 100% Stator Earth fault protection, Arc Protection and need for having frequency adaptiveness (10-75 Hz) to ensure protection availability during machine start-up phase. The proposed solution utilizing highly-available and fast Ethernet ne...

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Field-Driven Motion of Ferrofluids in Biaxial Magnetic Nanowire with Inertial Effects

Numerical Heat Transfer and Fluid Flow, 2018

This work deals with the field-driven motion of magnetic nanofluids in biaxial ferromagnetic nano... more This work deals with the field-driven motion of magnetic nanofluids in biaxial ferromagnetic nanowire in the presence of inertial effects and crystallographic defects. We obtained the analytical results under the theoretical model of extended Landau–Lifshitz–Gilbert equation comprising the nonlinear dissipation components, viz., dry friction and viscous along with the inertial effects. More specifically, using the regular perturbation expansion technique, we derive an expression for the leading order traveling wave solutions under the action of the small transverse magnetic field.

Hybrid Power System Based on Renewable Energies: A Future for Sustainable Energy Solutions

Electricity is recognized as the key driver of economic growth and development for any developing... more Electricity is recognized as the key driver of economic growth and development for any developing country. Most of the electricity generation in India is carried by conventional energy source which also heavily harm the eco-system by the emissions of greenhouse gasses but still around one third of total population in India has no access to electricity, this is due to rapid growth of population and also the fact that extension of existing grid is a long term process. This work gives an overview on the role of hybrid Renewable Energy Sources (RES) precisely solar and wind to meet the electricity demand of country keeping in view the production and consumption. It also deals with the concepts of using hybrid RES which may provide an intermediary solution especially for small towns and villages which are yet to be electrified under rural electrification program. The major system components of a PV-wind hybrid system and their technological configurations along with design parameters for...

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Can yield, soil C and aggregation be improved under long‐term conservation agriculture in the eastern Indo‐Gangetic plain of India?

European Journal of Soil Science, 2021

Deteriorating soil health, diminishing soil organic carbon (SOC), development of subsurface hard ... more Deteriorating soil health, diminishing soil organic carbon (SOC), development of subsurface hard compact layer and declining system productivity are barriers to achieving sustainable production in the traditional rice–wheat cropping system (TA) in the eastern Indo‐Gangetic Plain of India. Conservation agriculture (CA), which favours minimum soil disturbance, crop residue retention and crop diversification could be a viable alternative to the TA to address most of those major problems. With that in mind, a long‐term experiment is being implemented at ICAR‐RCER, Patna, Bihar, India, with four treatments: (a) TA, (b) full CA (fCA) and (c and d) partial CA (pCA1 and pCA2), differing in crop establishment methods, cropping system and crop residue management in a randomized complete block design. Measurement of soil health parameters was carried out in the 11th year of the experiment. The results revealed a beneficial effect of CA and 46 and 40% increase in SOC concentration and stock, re...

Field-driven magnetization reversal in a three-dimensional network of ferromagnetic ellipsoidal samples

Rendiconti del Circolo Matematico di Palermo Series 2, 2019

The field-driven magnetization reversal in a three-dimensional network of ferromagnetic particles... more The field-driven magnetization reversal in a three-dimensional network of ferromagnetic particles of ellipsoidal shape is analytically studied with an emphasis on coupling among the particles. The considered governing dynamics is the Landau–Lifshitz equation of micromagnetism which delineates the motion of magnetization inside the ferromagnetic medium. The analytical results explicate the stability and controllability (reversal) of the relevant configurations of magnetization which are established under the sufficient conditions. To reverse the magnetization direction in the particles, we use the control as a magnetic field generated by a dipole whose position and strength can be chosen.

On the statics and dynamics of transverse domain walls in bilayer piezoelectric-magnetostrictive nanostructures

Applied Mathematical Modelling, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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On the dynamics of transverse domain walls in biaxial magnetic nanostrips with crystallographic defects

AIP Conference Proceedings, 2018

On Controllability of a Two-Dimensional Network of Ferromagnetic Ellipsoidal Samples

Differential Equations and Dynamical Systems, 2018

In this article, we address the problem of stability and controllability of twodimensional networ... more In this article, we address the problem of stability and controllability of twodimensional network of ferromagnetic particles of ellipsoidal shapes. The dynamics of magnetization inside the ferromagnetic material is governed by the Landau-Lifschitz equation of micromagnetism which is non-linear and parabolic in nature. The control is the magnetic field generated by a dipole whose position and amplitude can be selected. In the absence of control, first we prove the exponential stability of the relevant configurations of the network. Then, we investigate the controllability by the means of external magnetic field induced by the magnetic dipole.

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On the stability of steady-states of a two-dimensional system of ferromagnetic nanowires

Journal of Applied Analysis, 2017

We investigate the stability features of steady-states of a two-dimensional system of ferromagnet... more We investigate the stability features of steady-states of a two-dimensional system of ferromagnetic nanowires. We constitute a system with the finite number of nanowires arranged on the ( e → 1 , e → 2 ) {(\vec{e}_{1},\vec{e}_{2})} plane, where ( e → 1 , e → 2 , e → 3 ) {(\vec{e}_{1},\vec{e}_{2},\vec{e}_{3})} is the canonical basis of ℝ 3 {\mathbb{R}^{3}} . We consider two cases: in the first case, each nanowire is considered to be of infinite length, whereas in the second case, we deal with finite length nanowires to design the system. In both cases, we establish a sufficient condition under which these steady-states are shown to be exponentially stable.

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On the Evolution of Transverse Domain Walls in Biaxial Magnetic Nanowires

Materials Today: Proceedings, 2017

In this article, we analyze the dynamics of transverse domain walls in the framework of one-dimen... more In this article, we analyze the dynamics of transverse domain walls in the framework of one-dimensional biaxial magnetic nanowires induced by the small applied magnetic fields. The evolution of magnetization in the nanowire is governed by the modified version of Landau-Lifshitz-Gilbert equation which consists of nonlinear dissipations namely dry-friction and viscous. We investigate the features of traveling wave solutions using the perturbation expansion technique. More precisely, we derive an expression for the zero order traveling wave solutions under the action of small and mild transverse magnetic fields.

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Comprehensive physiological analyses and reactive oxygen species profiling in drought tolerant rice genotypes under salinity stress

Physiology and molecular biology of plants : an international journal of functional plant biology, 2017

Rice being a staple cereal is extremely susceptible towards abiotic stresses. Drought and salinit... more Rice being a staple cereal is extremely susceptible towards abiotic stresses. Drought and salinity are two vital factors limiting rice cultivation in Eastern Indo-Gangetic Plains (EIGP). Present study has intended to evaluate the consequences of salinity stress on selected drought tolerant rice genotypes at the most susceptible seedling stage with an aim to identify the potential multi-stress (drought and salt) tolerant rice genotype of this region. Genotypic variation was obvious in all traits related to drought and salt susceptibility. IR84895-B-127-CRA-5-1-1, one of the rice genotypes studied, exhibited exceptional drought and salinity tolerance. IR83373-B-B-25-3-B-B-25-3 also displayed enhanced drought and salt tolerance following IR84895-B-127-CRA-5-1-1. Variations were perceptible in different factors involving photosynthetic performance, proline content, lipid peroxidation, K(+)/Na(+) ratio. Accumulation of reactive oxygen species (ROS) disintegrated cellular and sub-cellular...

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Heat stress induced impairment of starch mobilisation regulates pollen viability and grain yield in wheat: Study in Eastern Indo-Gangetic Plains

Field Crops Research, 2017

Delayed sowing of spring wheat due to late harvesting of long duration rice varieties sown in Eas... more Delayed sowing of spring wheat due to late harvesting of long duration rice varieties sown in Eastern Indo-Gangetic Plains (EIGP), results in yield loss associated with high temperatures. Present study intended to evaluate the consequences of high temperature on physiology, yield attributes and yield of spring wheat genotypes (n = 30) sown in the field for three consecutive winter seasons with different sowing windows; November (timely), December (late) and January (very late). The average temperature during anthesis stage of late (LS) and very late sowing (VLS) conditions were 2.7 • C and 5.2 • C higher than that of the timely sowing (TS) condition, which caused an average yield reduction of 18% under LS and 34% under VLS conditions as compared to the TS condition. Heat stress induced 8.6 days reduction in average grain filling duration under LS and 12.6 days under VLS condition, in turn caused 17 and 39% respective decrease in the test weight. High heritability was observed for tiller no. m −2 , spike length, membrane stability index and grain no. spike −1 while low heritability for grain yield and thousand grain weight among the genotypes studied. In our study, genotypic variation was obvious in all traits regarding thermal susceptibility. Halna, one of the wheat lines studied, displayed extreme heat tolerance among the considered genotypes with the lowest heat susceptibility index for grain yield (HSI < 0.5). NW1012 and Raj4238 presented high yield under TS conditions but could not sustain their ability when exposed to heat stress (HSI > 1.0). Furthermore, high temperature driven degradation of chlorophyll probably reduced photosynthetic capacity. Moreover, impaired transport of photosynthate (starch mobilization) from green foliage (source) to anther tissues (sink) leaded to high pollen mortality and thereby decreased grain yield. The results suggested that high temperature caused the significant negative influence on wheat genotypes at anthesis stage establishing a direct association of photosynthesis with starch mobilisation, pollen viability and grain yield. The study also introduced a crop model system for further revelation of the molecular background of thermo-tolerance in plants.

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Effect of different rice establishment methods on soil physical properties in drought-prone, rainfed lowlands of Bihar, India

Soil Research, 2016

To enhance productivity, alleviate environmental and management constraints, and enhance farmers’... more To enhance productivity, alleviate environmental and management constraints, and enhance farmers’ incomes in the rice–wheat cropping system of the Indo Gangetic Plains, new approaches that are labour-saving, more productive and sustainable need to be developed. Most systems of rice cultivation use puddling to prepare the seedbed and control weeds in rice fields of rainfed, stress-prone environments. This practice might be helpful to reduce weed pressure and obtain slightly higher productivity, but might have negative impacts on soil physical properties. A better understanding is needed of the comparative advantage of unpuddled rice fields for maintaining good soil physical properties. To study the effect of different rice establishment methods on soil physical properties in a rice–wheat cropping system, we analysed soil samples in 2 years (2012–13 and 2013–14) from an experiment testing puddled and unpuddled rice-establishment methods. The treatments were: (i) puddled, transplanted ...

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Effect of water stress at reproductive stage on yield potential and stability of rice (Oryza sativa L.) genotypes grown in rainfed lowland conditions

Electronic Journal of Plant Breeding, 2014

The present study was conducted at ICAR research complex for eastern region, Patna during kharif ... more The present study was conducted at ICAR research complex for eastern region, Patna during kharif 2012 and 2013 with objective to identify rice genotypes having high yield potential and stability under water stress (drought) conditions. Fifteen rice (Oryza sativa L.) genotypes were grown under irrigated and water stress conditions. Water stress was imposed at reproductive stage by withholding irrigation supply. Yield and yield attributesof rice genotypes under water stress condition were recorded. The effects of water stress on various physio-morphological traits associated with drought tolerance were also studied at reproductive stage. Results revealed that, significant yield decline was observed in most of the genotypes grown under stress condition compared to non-stress condition. Drought susceptibility index (DSI) and relative grain yield (RY) were used to illustrate yield stability and yield potential, respectively. Significant variation in drought susceptibility index and relative yield values within genotypes were observed. The DSI values ranged from 0.68 to 1.46 and the mean RY values were 0.85 for irrigated plots and 0.77 for water stressed plots. The rice genotypes IR 83376-B-B-24-2, IR 83373-B-B-24-3 IR 84895-B-B-127-CRA-5-1-1 and IR83387-B-B-27-4 showed high yield potential and stability (i.e. DSI<1; and RY>mean RY). These drought tolerant genotypes were also superior in terms of grain yield and higher content of desired physio-morphological traits in terms of plant biomass, relative water content, soluble protein and proline content. These drought tolerant rice genotypes may be adopted in large area in rainfed lowland ecosystem where drought is frequent, particularly at reproductive stage.

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Sharad Dwivedi

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