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Nonlinear vibration of multi-walled carbon nanotubes with initial curvature resting on elastic foundations in a nonlinear thermo-magnetic environment

Sobamowo Gbeminiyi, Akanum James, Adeleye Olurotimi, Akingbade Samuel, Yinusa Ahmed

Engineering Transactions

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2021

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Vol. 69, iss. 2

87--165

EN

The present work focuses on nonlinear dynamics models of multi-walled carbon nanotubes with initial curvature resting on Winkler-Pasternak elastic foundations in a nonlinear thermomagnetic environment using nonlocal elasticity theory. The derived systems of nonlinear vibration models are solved with the aid of the Galerkin decomposition and the homotopy perturbation method. Effects of temperature, magnetic field, multi-layer, and other thermomechanical parameters on the dynamic responses of the slightly curved multi-walled carbon nanotubes are investigated and discussed. As the temperature increases, the frequency ratio decreases as the linear natural frequency of the system increases. The results reveal that the frequency ratios decrease as the number of nanotube walls, temperature, spring constants, magnetic field strength, and the ratio of the radius of curvature to the length of the slightly curved nanotubes increase. These trends are the same for all the boundary conditions considered. However, clamped-simple and clamped-clamped supported multi-walled nanotube have the highest and lowest frequency ratio, respectively. Also, from the parametric studies to control nonlinear vibration of the carbon nanotubes, it is shown that quadruple-walled carbon nanotubes can be taken as pure linear vibration even at any value of linear Winkler and Pasternak constants. Therefore, this can be used for the restraining of the chaos vibration in the objective structure. These research findings will assist the designers and manufacturers in developing multi-walled carbon nanotubes for various structural, electrical, mechanical, and biological applications, especially in the areas of designing nanoelectronics, nanodevices, nanomechanical systems, nanobiological devices, and nanocomposites, and particularly when they are subjected to thermal loads, magnetic fields and elastic foundations.

2

MHD effects on non-Newtonian power-law fluid past a continuously moving porous flat plate with heat flux and viscous dissipation

Kishan N., Shashidar Reddy B.

International Journal of Applied Mechanics and Engineering

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2013

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Vol. 18, no. 2

425--445

EN

The problem of a magneto-hydro dynamic flow and heat transfer to a non-Newtonian power-law fluid flow past a continuously moving flat porous plate in the presence of sucion/injection with heat flux by taking into consideration the viscous dissipation is analysed. The non-linear partial differential equations governing the flow and heat transfer are transformed into non-linear ordinary differential equations using appropriate transformations and then solved numerically by an implicit finite difference scheme. The solution is found to be dependent on various governing parameters including the magnetic field parameter M, power-law index n, suction/injection parameter ƒw, Prandtl number Pr and Eckert number Ec. A systematical study is carried out to illustrate the effects of these major parameters on the velocity profiles, temperature profile, skin friction coefficient and rate of heat transfer and the local Nusslet number.

3

Viscous dissipation effects on MHD flow of a conducting power-law fluid with a pressure gradient

Kishan N., Shashidar Reddy B.

International Journal of Applied Mechanics and Engineering

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2012

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Vol. 17, no. 1

101-112

EN

The problem of a steady two-dimensional flow of a conducting power-law fluid past a flat plate in the presence of a transverse magnetic field under the influence of a pressure gradient by considering viscous dissipation effects is studied. The resulting governing partial differential equations are transformed into a set of non linear ordinary differential equations using appropriate transformation. The set of non linear ordinary differential equations is first linearized by using the Quasi-linearization technique and then solved numerically by using an implicit finite difference scheme. The system of algebraic equations is solved by using the Gauss-Seidal iterative method. The energy equation for a special case for which a similarity solution exist is also considered. The effects of the power-law index, magnetic parameter, viscous dissipation and generalized Prandtl number on the velocity and temperature profiles are of special interest. Numerical results are tabulated for the skin friction co-efficient. Velocity and temperature profiles are drawn for different controlling parameters which reveal the tendency of the solution.

4

Determination of permanent, electromagnetic field influence on sewage sludges conditioning

Strzelczyk M., Kamizela T., Wolny L.

Environment Protection Engineering

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2002

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Vol. 28, nr 1

49-53

EN

In the paper, some investigations of sewage sludges' conditioning before their dewatering were presented. Sludges were subjected to action of permanent electromagnetic field of magnetic induction equal to 0.04 T, and then treated with polyelectrolytes. Time of electromagnetic field action was: 10, 20, 30, 40, 50 and 60 seconds. Sludges were subjected to two different systems of magnetic poles: (SN) and (NS). The efficiency of this method was tested not only for the sludges prepared in such a way, but also for the sludges treated using physicochemical method. In the chemical process of sewage sludges' conditioning, the optimal doses of polyelectrolytes (Zetag 92 and Praestol 644 BC) were applied. They were determined in the capillary suction time (CST) test. Conditioned sludges were dewatered in vacuum filtration process. Basic characteristic parameters of this process, i.e. resistivity, capillary suction time, final hydration and zeta potential, were established.

PL

Przedstawiono badania dotyczące sposobu kondycjonowania osadów ściekowych przed ich odwadnianiem. Na osady działano stałym polem elektromagnetycznym o indukcji magnetycznej 0,04 T, a następnie polielektrolitami. Czas ekspozycji osadów na działanie pola elektromagnetycznego wynosił 10, 20, 30, 40, 50, 60 sekund. Osady eksponowano w dwóch różnych układach biegunów magnetycznych: (SN) i (NS). Skuteczność tej metody badano dla osadów preparowanych nie tylko polem elektromagnetycznym, ale również metodą fizykochemiczną. W procesie chemicznego kondycjonowania osadów ściekowych stosowano optymalne dawki polielektrolitów Zetag 92 oraz Praestol 644 BC, ustalone na podstawie testu CSK. Kondycjonowane osady odwadniano metodą filtracji próżniowej. Wyznaczono podstawowe parametry charakterystyczne dla tego procesu: opór filtracji, czas ssania kapilarnego, uwodnienie końcowe oraz potencjał elektrokinetyczny.