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1

Chaotic convection of viscoelastic fluid in porous medium under G-jitter

Bhadauria B. S., Singh A., Singh M. K.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 1

37--51

EN

The present article aims at investigating the effect of gravity modulation on chaotic convection of a viscoelastic fluid in porous media. For this, the problem is reduced into Lorenz system (non-autonomous) by employing the truncated Galerkin expansion method. The system shows transitions from periodic to chaotic behavior on increasing the scaled Rayleigh number R. The amplitude of modulation advances the chaotic nature in the system while the frequency of modulation has a tendency to delay the chaotic behavior which is in good agreement with the results due to [1]. The behavior of the scaled relaxation and retardation parameter on the system is also studied. The phase portrait and time domain diagrams of the Lorenz system for suitable parameter values have been used to analyze the system.

2

A Study on the Wilkins and Forchheimer Equations used in Coarse Granular Media Flow

Banerjee A., Pasupuleti S., Singh M. K., Kumar G. N. P.

Acta Geophysica

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2018

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Vol. 66, no. 1

81--91

EN

Complexity of the pore geometry and the random nature of flow velocity make it difficult to predict and represent post laminar flow through porous media. Present study experimentally investigates the applicability of Forchheimer and Wilkins equations for post laminar flow where Darcy’s law is invalid due to predominant inertial effect. It is observed that both porosity and media size have significant influence over the coefficients of the Forchheimer coefficients. To incorporate the effect of porosity and media size, behaviour of Forchheimer coefficients are investigated with hydraulic radius as characteristic length. An inversely proportional variation trend is found for all the present and earlier reported data. A new empirical relation between Forchheimer coefficients and hydraulic radius is obtained which can be universally applicable for all media size and porosity. Coefficients of the Wilkins equation are found to be non-deviating for different hydraulic radius in the present study and in the reported literature validating its applicability in predicting the non laminar flow through porous media. Further the Wilkins equation is modified after incorporating the correction factors for better applicability on the field.

3

Solution of one-dimensional space- and time-fractional advection–dispersion equation by homotopy perturbation method

Singh M. K., Chatterjee A.

Acta Geophysica

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2017

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Vol. 65, no. 2

353--361

EN

This study develops solution of one-dimensional space–time fractional advection–dispersion equation (FADE). Various forms of dispersion and velocity profiles (i.e. space dependent and both space–time dependent) are considered throughout the study. Homotopy perturbation method (HPM) is used to solve the problem semi-analytically. The advantage of HPM is that it does not require much information about the boundary of the aquifer. The initial condition may be measured for an aquifer, but sometimes it is very difficult to specify the boundary conditions. The FADE is employed for modeling the fate of contaminants in both homogeneous and heterogeneous porous formations subject to an increasing spatially dependent source condition. It is found that the contaminant concentration changes with the order of FADE as fractional-order derivative contains the memory of the system, i.e. how the system changes from one integer order to another integer order. FADEs are used to model the non-local system, hence this study helps understand the physical meaning of parameters involved in the velocity and dispersion.

4

Stability analysis and internal heating effect on oscillatory convection in a viscoelastic fluid saturated porous medium under gravity modulation

Bhadauria B. S., Singh M. K., Singh A., Singh B. K., Kiran P.

International Journal of Applied Mechanics and Engineering

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2016

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Vol. 21, no. 4

785--803

EN

In this paper, we investigate the combined effect of internal heating and time periodic gravity modulation in a viscoelastic fluid saturated porous medium by reducing the problem into a complex non-autonomous Ginzgburg-Landau equation. Weak nonlinear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number is obtained in terms of the amplitude for oscillatory mode of convection. The influence of viscoelastic parameters on heat transfer has been discussed. Gravity modulation is found to have a destabilizing effect at low frequencies and a stabilizing effect at high frequencies. Finally, it is found that overstability advances the onset of convection, more with internal heating. The conditions for which the complex Ginzgburg-Landau equation undergoes Hopf bifurcation and the amplitude equation undergoes supercritical pitchfork bifurcation are studied.

5

Experimental Studies on Advanced Sheet Explosive Formulations Based on 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and Hydroxyl Terminated Polybutadiene (HTPB), and Comparison with a RDX-based System

Jangid S. K., Talawar M. B., Singh M. K., Nath T., Sinha R. K.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 1

135--147

EN

The present investigation reports the use of 2,4,6,8,10,12-hexanitro2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) in sheet explosive formulations. In this study, hydroxyl terminated polybutadiene (HTPB) based sheet explosives were prepared incorporating the powerful explosive CL-20 as a partial replacement for hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX). The effects of incorporating CL-20 on the performance, sensitivity, thermal and mechanical properties of the sheet explosive compositions are reported. Sheet explosive formulation containing 80% of RDX and 20% of HTPB-binder was studied as control sample. HTPBbinder consisted of 12% HTPB, 2.9% dioctyl adipate (DOA) and 5.1% dioctyl phthalate (DOP). HTPB was cured with 4,4’-methylene diphenyl di-isocyanate (MDI) to form urethane linkages. The incorporation of 20% of CL-20 in place of RDX led to a remarkable increase in the velocity of detonation (VOD), of the order of 7680 m/s, and to better mechanical properties in terms of tensile strength (1.14 MPa) compared to the control formulation [RDX /HTPB-binder (80/20)]. The 20% CL-20 incorporated sheet explosive formulation also showed remarkable increases in impact and shock sensitivity. Thermal analysis of the sheet explosive compositions has also been carried out using differential scanning calorimetry (DSC).

6

Experimental Studies on a High Energy Sheet Explosive Based on RDX and Bis(2,2-dinitropropyl) Formal/Acetal (BDNPF/A)

Jangid S. K., Singh M. K., Solanki V. J., Pandit G., Nath T., Sinha R. K.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 3

557--566

EN

A plastic bonded explosive (PBX) in the form of a sheet explosive was formulated with 1,3,5-trinitro-1,3,5-triazinane (RDX) dispersed in a polymeric matrix of a thermoplastic linear polyurethane and a 50/50 wt.% eutectic mixture of energetic plasticizers, viz., bis(2,2-dinitropropyl)formal (BDNPF) and bis(2,2-dinitropropyl)acetal (BDNPA) was used to increase the performance of the sheet explosive in terms of its velocity of detonation (VOD). The sheet explosives were prepared by a rolling process. Natural rubber (ISNR-5) based sheet explosive was taken as the standard composition. The study showed that the BDNPF/A based sheet explosive has a velocity of detonation of 7850 m/s, which is about 900 m/s higher than the standard composition. Thermal analysis of the sheet explosive formulations was performed using differential scanning calorimetry (DSC).

7

Pollutant’s Horizontal Dispersion Along and Against Sinusoidally Varying Velocity from a Pulse Type Point Source

Singh M. K., Mahato N. K., Kumar N.

Acta Geophysica

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2015

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Vol. 63, no. 1

214--231

EN

An analytical solution of a two-dimensional advection diffusion equation with time dependent coefficients is obtained by using Laplace Integral Transformation Technique. The horizontal medium of solute transport is considered of semi-infinite extent along both the longitudinal and lateral directions. The input concentration is assumed at an intermediate position of the domain. It helps to evaluate concentration level along the flow as well as against the flow through one model only. The source of the input concentration is considered to be of pulse type. In the presence of the source, it is assumed to be decreasing very slowly with time, and just after the elimination of the source it is assumed to be zero. The dispersion coefficient and the advection parameter are considered directly proportional to each other. The analytical solution may be used to predict the solute concentration level with position and time in an open medium as well as in a porous medium. The effect of heterogeneity on the solute transport may also be predicted.

8

Cosmetotextiles: State of Art

Singh M. K., Varun V K, Behera B K

Fibres & Textiles in Eastern Europe

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2011

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Vol. 19, no. 4 (87)

27--33

EN

The main aim of this article is to collect the scattered knowledge of Cosmetotextiles and present it to the world scientific community for scrutiny. Various aspects of Cosmetotextiles are compiled systematically and oriented towards product development. The technology of Cosmetotextiles is at the neonatal stage. The joint efforts of textile technologists, biochemists, cosmetic experts and medicos can achieve challenging targets in the field of Cosmetotextiles. Various derivatives of metals, plants and animals are used in pure and derivative form to generate cosmetic functionality in textiles. Various routes for the incorporation of cosmetic potentail in textiles are available, of which microencapsulation and the use of cyclodextrin as cage material are the most popular. The content of moisture on skin surface is a key parameter in maintaining skin elasticity and glowing potential. The characterization of Cosmetotextiles is a difficult task, but the Europeans have taken the lead by classifying and standardising the testing of the cosmetic effects of cosmetotextiles.

PL

Celem artykułu jest przedstawienie wiedzy rozrzuconej w różnych źródłach na temat nowo wprowadzonego pojęcia kosmotekstyliów. Przedstawiono podział kosmotekstyliów, kierunki możliwych aplikacji, stosowane zróżnicowane technologie dla otrzymania pożądanego efektu, środki wywołujące odpowiedni efekt wprowadzane do włókien przędz, tkanin lub dzianin oraz gotowych produktów. Opisano również stosowane sposoby badań i testów. Podano także liczne przykłady współcześnie stosowanych kosmotekstyliów.

9

Study of low temperature inactivation of spores using microwave excited air plasma

Nagatsu M., Singh M. K., Zhao Y., Fujioka Y., Ogino A.

Journal of Automation Mobile Robotics and Intelligent Systems

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2009

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Vol. 3, No. 4

108-111

EN

In the present study, we investigated the inactivation characteristics and contribution of different inactivating factors generated in a low temperature and low pressure nitrogen, oxygen and air-simulated plasma for the inactivation of Geobacillus stearothermophilus spores. We used three optical filters i.e. thin quartz (lambda>180 nm), lithium fluorine (LiF, lambda>120 nm) and Pyrex glass (lambda>300 nm) plates to identify the most efficient wavelength range. The effect of optical radiations alone was studied through placing a small isolated and evacuated chamber with spore sample inside the plasma chamber.

10

A Six-order Variant of Newton’s Method for Solving Nonlinear Equations

Singh M. K.

Computational Methods in Science and Technology

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2009

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Vol. 15, nr 2

185-193

EN

A new variant of Newton's method based on contra harmonic mean has been developed and its convergence properties have been discussed. The order of convergence of the proposed method is six. Starting with a suitably chosen x0, the method generates a sequence of iterates converging to the root. The convergence analysis is provided to establish its sixth order of convergence. In terms of computational cost, it requires evaluations of only two functions and two first order derivatives per iteration. This implies that efficiency index of our method is 1.5651. The proposed method is comparable with the methods of Parhi, and Gupta [15] and that of Kou and Li [8]. It does not require the evaluation of the second order derivative of the given function as required in the family of Chebyshev-Halley type methods. The efficiency of the method is tested on a number of numerical examples. It is observed that our method takes lesser number of iterations than Newton’s method and the other third order variants of Newton´s method. In comparison with the sixth order methods, it behaves either similarly or better for the examples considered.