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Article
Publication date: 4 March 2020

B. Mahanthesh

The magnetohydrodynamic (MHD) flow problems are important in the field of biomedical applications such as magnetic resonance imaging, inductive heat treatment of tumours…

Abstract

Purpose

The magnetohydrodynamic (MHD) flow problems are important in the field of biomedical applications such as magnetic resonance imaging, inductive heat treatment of tumours, MHD-derived biomedical sensors, micropumps for drug delivery, MHD micromixers, magnetorelaxometry and actuators. Therefore, there is the impact of the magnetic field on the transport of non-Newtonian Carreau fluid in the presence of binary chemical reaction and activation energy over an extendable surface having a variable thickness. The significance of irregular heat source/sink and cross-diffusion effects is also explored.

Design/methodology/approach

The leading governing equations are constructed by retaining the effects of binary chemical reaction and activation energy. Suitable similarity transformations are used to transform the governing partial differential equations into ordinary differential equations. Subsequent nonlinear two-point boundary value problem is treated numerically by using the shooting method based on Runge–Kutta–Fehlberg. Graphical results are presented to analyze the behaviour of effective parameters involved in the problem. The numerical values of the mass transfer rate (Sherwood number) and heat transfer rate (Nusselt number) are also calculated. Furthermore, the slope of the linear regression line through the data points is determined in order to quantify the outcome.

Findings

It is established that the external magnetic field restricts the flow strongly and serves as a potential control mechanism. It can be concluded that an applied magnetic field will play a major role in applications like micropumps, actuators and biomedical sensors. The heat transfer rate is enhanced due to Arrhenius activation energy mechanism. The boundary layer thickness is suppressed by strengthening the thickness of the sheet, resulting in higher values of Nusselt and Sherwood numbers.

Originality/value

The effects of magnetic field, binary chemical reaction and activation energy on heat and mass transfer of non-Newtonian Carreau liquid over an extendable surface with variable thickness are investigated for the first time.

Details

Multidiscipline Modeling in Materials and Structures, vol. 16 no. 5
Type: Research Article
ISSN: 1573-6105

Keywords

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Article
Publication date: 11 September 2019

C. RamReddy and P. Naveen

The purpose of this paper is to analyze the combined effects of thermal radiation and activation energy with a chemical reaction on the quadratic convective flow of a…

Abstract

Purpose

The purpose of this paper is to analyze the combined effects of thermal radiation and activation energy with a chemical reaction on the quadratic convective flow of a micropolar fluid over an inclined plate. Convective thermal boundary condition and suction/injection effects are considered at the surface of an inclined plate.

Design/methodology/approach

The convection along with nonlinear Boussinesq approximation (i.e. quadratic convection or nonlinear convection) and usual boundary layer assumptions is employed in the mathematical formulation. Highly coupled nonlinear governing equations are tackled by a combined local non-similarity and successive linearization techniques.

Findings

The behavior of various pertinent parameters on the fluid flow characteristics is conferred through graphs and it reveals that the qualitative behaviors of velocity, temperature, skin friction and heat transfer rates of a micropolar fluid are similar for Biot number and radiation parameters. The suction/injection and activation energy parameters increase the concentration of the micropolar fluid within the boundary layer, while the chemical reaction parameter reduces the concentration in the same region. Further, this quadratic convection shows a strong influence on the fluid flow characteristics and then the impact of pertinent parameters is more prominent on the physical quantities, compared therewith results of the linear convection.

Practical implications

This kind of investigation is useful in the mechanism of combustion, aerosol technology, high-temperature polymeric mixtures and solar collectors which are operated at moderate to very high temperatures.

Originality/value

This attempt is a unique contribution to the establishment of both micropolar fluid and activation energy. This kind of study even in the absence of quadratic convection is not yet noted.

Details

Multidiscipline Modeling in Materials and Structures, vol. 16 no. 1
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 6 November 2019

Ramani Mayappan, Amirah Salleh, Nurul Atiqah Tokiran and N.A. Awang

The purpose of this study is to investigate the addition of 0.05 Wt.% carbon nanotube (CNT) into the Sn-1.0Ag-0.5Cu (SAC) solder on the intermetallic (IMC) growth…

Abstract

Purpose

The purpose of this study is to investigate the addition of 0.05 Wt.% carbon nanotube (CNT) into the Sn-1.0Ag-0.5Cu (SAC) solder on the intermetallic (IMC) growth. Lead-based solders play an important role in a variety of applications in electronic industries. Due to the toxicity of the lead in the solder, lead-free solders were proposed to replace the lead-based solders. Sn-Ag-Cu solder family is one of the lead-free solders, which are proposed and considered as a potential replacement. Unfortunately, the Sn-Ag-Cu solder faces some reliability problems because of the formation of the thick intermetallic compounds. So the retardation of intermetallic growth is prime important.

Design/methodology/approach

The solder joint was aged under liquid state aging with soldering time from 1 to 60 min.

Findings

Two types of intermetallics, which are Cu6Sn5 and Cu3Sn were observed under a scanning electron microscope. The morphology of Cu6Sn5 intermetallic transformed from scallop to planar type as the soldering time increases. The addition of carbon nanotube into the SAC solder has retarded the Cu6Sn5 intermetallic growth rate by increasing its activation energy from 97.86 to 101.45 kJ/mol. Furthermore, the activation energy for the Cu3Sn growth has increased from 102.10 to 104.23 kJ/mol.

Originality/value

The increase in the activation energy indicates that the growth of the intermetallics was slower. This implies that the addition of carbon nanotube increases the reliability of the solder joint and are suitable for microelectronics applications.

Details

Soldering & Surface Mount Technology, vol. 32 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 29 November 2018

Gireesha B.J., M. Archana, B. Mahanthesh and Prasannakumara B.C.

The purpose of this paper is to explore the effects of binary chemical reaction and activation energy on nano Casson liquid flow past a stretched plate with non-linear…

Abstract

Purpose

The purpose of this paper is to explore the effects of binary chemical reaction and activation energy on nano Casson liquid flow past a stretched plate with non-linear radiative heat, and also, the effect of a novel exponential space-dependent heat source (ESHS) aspect along with thermal-dependent heat source (THS) effect in the analysis of heat transfer in nanofluid. Comparative analysis is carried out between the flows with linear radiative heat process and non-linear radiative heat process.

Design/methodology/approach

A similarity transformation technique is utilised to access the ODEs from the governed PDEs. The manipulation of subsequent non-linear equations is carried out by a well-known numerical approach called Runge–Kutta–Fehlberg scheme. Obtained solutions are briefly discussed with the help of graphical and tabular illustrations.

Findings

The effects of various physical parameters on temperature, nanoparticles volume fraction and velocity fields within the boundary layer are discussed for two different flow situations, namely, flow with linear radiative heat and flow with non-linear radiative heat. It is found that an irregular heat source/sink (ESHS and THS) and non-linear solar radiation play a vital role in the enhancement of the temperature distributions.

Originality/value

The problem is relatively original to study the effects of activation energy and binary chemical reaction along with a novel exponential space-based heat source on laminar boundary flow past a stretched plate in the presence of non-linear Rosseland radiative heat.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 1
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 5 October 2020

Ruichao Guo, Jianjun Wu and Yinxiang Ren

Accurate prediction of residual stress requires precise knowledge of the constitutive behavior of as-quenched material. This study aims to model the flow stress behavior…

Abstract

Purpose

Accurate prediction of residual stress requires precise knowledge of the constitutive behavior of as-quenched material. This study aims to model the flow stress behavior for as-quenched Al-Mg-Si alloy.

Design Methodology Approach

In the present work, the flow behavior of as-quenched Al-Mg-Si alloy is studied by the hot compression tests at various temperatures (573–723 K), strain rates (0.1–1 s−1) and cooling rates (1–10 K/s). Flow stress behavior is then experimentally observed, and an Arrhenius model is used to predict the flow behavior. However, due to the fact that materials parameters and activation energy do not remain constant, the Arrhenius model has an unsatisfied prediction for the flow behavior. Considering the effects of temperatures, strain rates and cooling rates on constitutive behavior, a revised Arrhenius model is developed to describe the flow stress behavior.

Findings

The experimental results show that the flow stress increases by the increasing cooling rate, increasing strain state and decreasing temperature. In comparison to the experimental data, the revised Arrhenius model has an excellent prediction for as-quenched Al-Mg-Si alloy.

Originality Value

With the revised Arrhenius model, the flow behaviors at different quenching conditions can be obtained, which is an essential step to the residual stress prediction when the model is implemented in a finite element code, e.g. ABAQUS, in the future.

Details

Engineering Computations, vol. 38 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 1 December 2001

Prasun K. Roy and D. Dutta Majumder

The approach of biocybernetics and non‐equilibrium systems dynamics is used to analyse biological, psychological, anthropological and cultural evolution. Using…

Abstract

The approach of biocybernetics and non‐equilibrium systems dynamics is used to analyse biological, psychological, anthropological and cultural evolution. Using experimental data, positive feedback of biological activation and Prigogine‐Einstein fluctuation analysis, the energy dissipation equations for biological and anthropological evolution are developed.

Details

Kybernetes, vol. 30 no. 9/10
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 20 August 2019

Atif Alkhazali, Morad Etier, Mohammad Aljarrah, Akram Alsukker and Fathy Salman

The purpose of this study is to investigate the effect of the considerable Ag2SO4 content on the electrical and dielectric properties of (AgPO3)1−x(Ag2SO4)x ion glass…

Abstract

Purpose

The purpose of this study is to investigate the effect of the considerable Ag2SO4 content on the electrical and dielectric properties of (AgPO3)1−x(Ag2SO4)x ion glass system as well as to extract thermodynamic parameters.

Design/methodology/approach

Glass samples of (AgPO3)1-x(Ag2SO4)x with different mole ratios of Ag2SO4 [x = 0.00, 0.10,0.15,0.20 and 0.25] have been synthesized and used. X-ray diffraction and differential thermal analysis were used to investigate structural and thermal properties, and then the electrical characterizations of the bulk glasses were performed in different frequency and temperature range.

Findings

For different ratios of Ag2SO4 on AgPO3, the bulk conductivity is enhanced with increasing the amount of Ag2SO4 until the composition of x = 0.20, after which the conductivity decreases. The general behavior of both ε’ and ε” decreases with increasing frequency and increases with increasing temperature. Complex impedance analysis studied by Z‘−Z’ and Cole–Cole plot at different temperatures revealed that bulk resistance decreases with temperature.

Originality/value

The calculated values of activation free energy, enthalpy and entropy change for different compositions of (AgPO3)1-x(Ag2SO4)x showed an increase in activation energy and enthalpy when Ag2SO4 ratio is increased in (AgPO3)1-x(Ag2SO4)x composition up to 20%, and then there is a decrease in their values at x = 25%, which may be explained based on non-bridging oxygen.

Details

World Journal of Engineering, vol. 16 no. 4
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 1 August 1943

N.A. de Bruyne

THE marked dependence of the strength of metals on temperature, and on rate of loading at high temperatures, can be explained by assuming that above the equi‐cohesive…

Abstract

THE marked dependence of the strength of metals on temperature, and on rate of loading at high temperatures, can be explained by assuming that above the equi‐cohesive temperature rupture takes place by plastic flow in a non‐homogeneous medium, consisting of rigid crystallites weakly cemented together. Although the stress concentrations required by the Griffith theory must still be operative above the equi‐cohesive temperature, it is suggested that they produce intergranular flow, rather than the elastic separation that occurs at temperatures below the equi‐cohesive temperature. A theory is developed based on the assumption that the strain energy at rupture reduces the energy of activation of the flow process, and the theory is shown to be in numerical agreement with the experimental results, if the energy of activation of the flow process is about one seventh of the latent heat of evaporation per gram atom. Values of the cohesive strengths and of the stress concentration factors are also derived.

Details

Aircraft Engineering and Aerospace Technology, vol. 15 no. 8
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 August 2004

G. Bereket, A. Pınarbaşı and C. Öğretir

The effect of benzimidazole‐2‐tione and benzoxazole‐2‐tione derivatives on the corrosion of aluminium in 0.1 M HCl has been investigated by a potentiostatic polarisation…

Abstract

The effect of benzimidazole‐2‐tione and benzoxazole‐2‐tione derivatives on the corrosion of aluminium in 0.1 M HCl has been investigated by a potentiostatic polarisation technique. Inhibition efficiencies were found to follow the order: benzimidazole‐2‐tione > 5‐methyl benzimidazole‐2‐tione > 5‐chloro benzimidazole‐2‐tione, while that of benzoxazole‐2‐tione derivatives were found to follow the order: 5‐methyl benzoxazole‐2‐tione > benzoxazole‐2‐tione > 5‐chloro benzoxazole‐2‐tione > 5‐nitro benzoxazole‐2‐tione. The inhibitive action of these heterocyclic compounds was mainly due to adsorption on the metal surfaces, which show parallelism with the calculated total negative charge of each of the molecules. Thermodynamic parameters, such as values of free energies of adsorption ΔGads and values of equilibrium constants Kads, were determined. Activation energies Ea, activation enthalpies ΔH* and activation entropies ΔS* were determined from the corrosion currents measured at different temperatures.

Details

Anti-Corrosion Methods and Materials, vol. 51 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 23 August 2011

Antonio Caballero and Jean‐Francois Molinari

This paper aims to describe a numerical approach to the fragmentation of kidney stones by direct impact.

Abstract

Purpose

This paper aims to describe a numerical approach to the fragmentation of kidney stones by direct impact.

Design/methodology/approach

The numerical approach consists of a Lagrangian finite element formulation with dynamic insertion of cohesive‐free surfaces. Cohesive free surfaces are governed by a damage constitutive model whereas the continuum part of the mesh remains linear elastic. The impact of the metallic probe of the medical device is modeled with a displacement control of the nodes inside the area of impact on the stone.

Findings

The results show the relation between the total energy transmitted during the impact with the damage and the fragmentation (number of fragments and number of microcrack clusters) of the kidney stone. The paper establishes the existence of both, an activation and saturation energy level, that delimit a range optimum working energy transmitted during the impact. In particular, the computations show that, for the calcium oxalate monohydrate stone, the maximum energy supplied by the medical device (Lithoclast) coincides with the saturation energy level.

Originality/value

In medical investigations, the experimentation is always restricted to the availability of patients or specimens. In the particular case of the elimination of renal calculi, the literature exhibits an extensive number of works reporting the practical experience of medical doctors. However, there is still a lack of information that might help to understand and to improve the comminution of kidney stones.

Details

Engineering Computations, vol. 28 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

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