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Article
Publication date: 1 December 1998

Abbas J. Ali

Takes a look at the state of Arab society. Classifies Arab individuals into eight categories – traditionalist, spectator, idealist, illusionist, transitional, revivalist…

Abstract

Takes a look at the state of Arab society. Classifies Arab individuals into eight categories – traditionalist, spectator, idealist, illusionist, transitional, revivalist, manipulator, and existentialist. Explores each of these in more depth, providing some specific illustrative examples. Claims that work values have changed in Arab society, with the new generation taking part in political and economic decision making. Reflects on the implications this could have for multinational corporations. Concludes that Arab society is in transition, discarding its old tribal and traditionalist beliefs to move towards the basis for a more modern economy. Provides some tables summarizing each typology of individual and the attributes required to conduct business successfully.

Details

International Journal of Sociology and Social Policy, vol. 18 no. 11/12
Type: Research Article
ISSN: 0144-333X

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Article
Publication date: 8 June 2021

Najiyah Safwa Khashi'ie, Norihan Md Arifin, Natalia C. Rosca, Alin V. Rosca and Ioan Pop

The purpose of this paper is to study the effects of thermal radiation and homogeneous-heterogeneous reactions in the three-dimensional hybrid nanofluid flow past a…

Abstract

Purpose

The purpose of this paper is to study the effects of thermal radiation and homogeneous-heterogeneous reactions in the three-dimensional hybrid nanofluid flow past a permeable stretching/shrinking sheet.

Design/methodology/approach

The combination of aluminum oxide (Al2O3) and copper (Cu) nanoparticles with total volumetric concentration is numerically analyzed using the existing correlations of hybrid nanofluid. With the consideration that both homogeneous and heterogeneous reactions are isothermal while the diffusion coefficients of both autocatalyst and reactant are same, the governing model is simplified into a set of differential (similarity) equations.

Findings

Using the bvp4c solver, dual solutions are presented, and the stability analysis certifies the physical/real solution. The findings show that the suction parameter is requisite to induce the steady solution for shrinking parameter. Besides, the fluid concentration owing to the shrinking sheet is diminished with the addition of surface reaction.

Originality/value

The present findings are novel and can be a reference point to other researchers to further analyze the heat transfer performance and stability of the working fluids.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 24 September 2019

Mohamed I.A. Othman and Sudip Mondal

The purpose of this paper is to introduce the phase-lag models (Lord-Shulman, dual-phase-lag and three-phase-lag) to study the effect of memory-dependent derivative and…

Abstract

Purpose

The purpose of this paper is to introduce the phase-lag models (Lord-Shulman, dual-phase-lag and three-phase-lag) to study the effect of memory-dependent derivative and the influence of thermal loading due to laser pulse on the wave propagation of generalized micropolar thermoelasticity. The bounding plane surface is heated by a non-Gaussian laser beam with a pulse duration of 10 nanoseconds.

Design/methodology/approach

The normal mode analysis technique is used to obtain the exact expressions for the displacement components, the force stresses, the temperature, the couple stresses and the micro-rotation. Comparisons are made with the results predicted by three theories of the authors’ interest. Excellent predictive capability is demonstrated at a different time also.

Findings

The effect of memory-dependent derivative and the heat laser pulse on the displacement, the temperature distribution, the components of stress, the couple stress and the microrotation vector have been depicted graphically.

Research limitations/implications

Some particular cases are also deduced from the present investigation.

Originality/value

The numerical results are presented graphically and are compared with different three theories for both in the presence and absence of memory-dependent effect and with the results predicted under three theories for two different values of the time.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 4 January 2016

A.A. Fadda and N.S. Abbas

– The purpose of this paper is to discuss the synthesis of new azo disperse dyes containing pyridine ring for dyeing acetate polyester and other fibres.

Abstract

Purpose

The purpose of this paper is to discuss the synthesis of new azo disperse dyes containing pyridine ring for dyeing acetate polyester and other fibres.

Design/methodology/approach

Cycloaddition reaction of 3-formylchromone (Compound 1) with ethyl vinyl ether (Compound 2) afforded 3-ethoxy-4,4a-dihyro-3H,10H-pyrano[4,3-b]chromen-10-one (Compound 3). Reaction of 3 with aqueous ammonium sulphite in ethanol furnishes 3-(2-hydroxybenzoyl)pyridine (Compound 5). Compound 5 was fully characterised by spectroscopic techniques. Ten arylazo derivatives of Compound 6 have been prepared for use as dyestuffs. The effect of the nature and orientation of substituents in the diazonium component on the colour of azo dyes is discussed. Dyeing performance of the dyes on different fibres has also been assessed.

Findings

Most of the dyes showed good affinity to polyester fibres. On the other hand, polyacrylic fibres were only stained to weak shades.

Originality/value

No details regarding the synthesis and dyeing performance of such dyes are reported before in the literature.

Details

Pigment & Resin Technology, vol. 45 no. 1
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 16 July 2020

Maryiam Javed

objective of the present investigation is to examine the influence of Hall on the peristaltic mechanism of Johnson-Segalman fluid in a heated channel with elastic walls…

Abstract

Purpose

objective of the present investigation is to examine the influence of Hall on the peristaltic mechanism of Johnson-Segalman fluid in a heated channel with elastic walls. The transmission of heat is carried out. Relevant equations are computed for heat transfer coefficient, temperature and velocity. Low Reynolds number assumptions and long wavelength are employed. The interpretation of various parameters is analyzed. The results indicate that the heat transfer coefficient, temperature and velocity are larger for viscous material in comparison with Johnson-Segalman material.

Design/methodology/approach

The transmission of heat is carried out. Relevant equations are computed for heat transfer coefficient, temperature and velocity. Low Reynolds number assumptions and long wavelength are employed. The interpretation of various parameters is analyzed. The results indicate that the heat transfer coefficient, temperature and velocity are larger for viscous material in comparison with Johnson-Segalman material.

Findings

The formulation of paper is executed as follows. Section 2 comprises problem summary and mathematical design. Solution methodology is discussed, and expressions for temperature, velocity and coefficient of heat transfer are derived in Section 3. Graphical outcomes for the parameters are reported in Section 4. Conclusions are outlined in Section 5.

Practical implications

Peristaltic phenomenon of fluids has a definite role in many physiological, industrial and engineering processes. The mechanical devices for instance finger and roller pumps operate via this process, and it is quite significant for vasomotion of blood vessels, consumption of food via esophagus, chyme flow in gastrointestinal zone, toxic liquid flow in nuclear industry and transport of corrosive fluids.

Originality/value

Literature review witnesses that information about peristalsis of conducting fluid in a heated channel with flexible walls and Hall effect is scarce. So, our goal is to discuss the peristaltic activity of non-Newtonian fluids in flexible channel. Johnson-Segalman fluid is taken into account. This model is used to allow non-affine deformations. Experimentalists relate “spurt” with wall slip. That is why the work presented is original.

Details

Multidiscipline Modeling in Materials and Structures, vol. 17 no. 2
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 6 November 2017

Abdel-Zaher A. Elassar, Saleh M. Al-Mousawi, Maher Helmi Helal and Mohamed E. Elgazzar

The purpose of this paper is to prepare new disperse dyes and apply for dying polyester fabrics.

Abstract

Purpose

The purpose of this paper is to prepare new disperse dyes and apply for dying polyester fabrics.

Design/methodology/approach

The synthetic reaction was carried out through two steps: preparation of arylhydrazones and alkylation using enaminone and dimethylaminovinyl-pyridazine. The high temperature method was used to apply these dyes to polyester fibres.

Findings

The study revealed that there is a significant effect of the new prepared disperse dyes on polyester fabrics. The structures of the prepared dyes were established based on elemental analysis and spectral data (infra red (IR), mass spectrometry (MS) and proton nuclear magnetic resonance (1H-NMR), carbon 13th nuclear magnetic resonance (13C-NMR)).

Research limitations/implications

Disperse dyes containing heterocyclic moiety have attracted great academic and industrial attention owing to their significant. The potential of using disperse dyes easily prepared from arylhydrazones are promise broad applications for these dyes.

Practical implications

The presence of N-thienyl and N-pyridazinyl in the structure of the synthesised disperse dyes would be expected to add the bioactivity advantage. Also, it can be used in formulating the antimicrobial fabrics.

Social implications

The N-thienyl and N-pyrdiazinyl derivatives of azo dyes are expected to be superior to in the application for fabrics. It may be useful for other applications like painting.

Originality/value

This paper helps to synthesise novel thiophene or pyridazine-based dyestuff for application in dying properties on polyester fabric and study their fastness properties.

Details

Pigment & Resin Technology, vol. 46 no. 6
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 4 August 2021

Nur Syahirah Wahid, Norihan Md Arifin, Najiyah Safwa Khashi'ie, Ioan Pop, Norfifah Bachok and Ezad Hafidz Hafidzuddin

The purpose of this paper is to numerically investigate the hybrid nanofluid flow with the imposition of magnetohydrodynamic (MHD) and radiation effects alongside the…

Abstract

Purpose

The purpose of this paper is to numerically investigate the hybrid nanofluid flow with the imposition of magnetohydrodynamic (MHD) and radiation effects alongside the convective boundary conditions over a permeable stretching/shrinking surface.

Design/methodology/approach

The mathematical model is formulated in the form of partial differential equations (PDEs) and are then transformed into the form of ordinary differential equations (ODEs) by using the similarity variables. The deriving ODEs are solved numerically by using the bvp4c solver in MATLAB software. Stability analysis also has been performed to determine the stable solution among the dual solutions obtain. For method validation purposes, a comparison of numerical results has been made with the previous studies.

Findings

The flow and the heat transfer of the fluid at the boundary layer are described through the plot of the velocity profile, temperature profile, skin friction coefficient and local Nusselt number that are presented graphically. Dual solutions are obtained, but only the first solution is stable. For the realizable solution at the shrinking surface, the proliferation of nanoparticle volume fraction (copper) and magnetic (magnetohydrodynamics) parameters can impede the boundary layer separation. Also, Biot number could enhance the temperature profile and the heat transfer rate at the shrinking surface region. The incrementation of 0.1% of Biot number has enhanced the heat transfer rate by approximately 0.1% and the incrementation of 0.5% volume fraction for copper has reduced the heat transfer rate by approximately 0.17%.

Originality/value

The presented model and numerical results are original and new. It can be used as a future reference for further investigation and related practical application. The main contribution of this investigation includes giving the initial prediction and providing the numerical data for the other researchers for their future reference regarding the impacts of nanoparticles volumetric concentration towards the main physical quantities of interest in the presence of magnetic and radiation parameters with the convective boundary conditions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 10 December 2019

Muhammad Ijaz Khan, Sohail Ahmad Khan, Tasawar Hayat, Muhammad Waqas and Ahmed Alsaedi

The purpose of this paper is to investigate the entropy optimization in magnetohydrodynamic hybrid nanomaterials flows toward a stretchable surface. The energy expression…

Abstract

Purpose

The purpose of this paper is to investigate the entropy optimization in magnetohydrodynamic hybrid nanomaterials flows toward a stretchable surface. The energy expression is modeled subject to dissipation, heat generation/absorption and Joule heating. Here silicon dioxide (SiO2) and molybdenum disulfide (MoS2) as nanoparticles and propylene glycol (C3H8O2) as base fluid, respectively. Furthermore, the authors discussed the comparative study of molybdenum disulfide and silicon dioxide diluted in propylene glycol. The total entropy optimization rate is computed through implementation of the second law of thermodynamics.

Design/methodology/approach

The nonlinear partial differential system is reduced to an ordinary one through implementation of transformation. Newton built-in shooting method is used for computational results for the given system. Influences of various flow variables on the temperature, Bejan number, velocity, concentration and entropy generation rate are examined graphically for both nanoparticles (SiO2 and MoS2). Gradients of velocity and temperature are computed numerically for various physical parameters. Also, take the comparison between the present and previously published results in tabulated form.

Findings

For higher estimation of ϕ both temperature and velocity are enhanced. Entropy optimization and Bejan number have the opposite outcome for viscosity parameter. Temperature and velocity have opposite behaviors for larger values of magnetic parameter. Molybdenum disulfide (MoS2) is more efficient than silicon dioxide (SiO2).

Originality/value

No such work is yet published in the literature.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 5 August 2021

Ioan Pop, Iskandar Waini and Anuar Ishak

This study aims to explore the stagnation flow over a shrinking surface in a hybrid nanofluid consists of Al2O3 and Cu nanoparticles. Here, the flow is subjected to the…

Abstract

Purpose

This study aims to explore the stagnation flow over a shrinking surface in a hybrid nanofluid consists of Al2O3 and Cu nanoparticles. Here, the flow is subjected to the magnetohydrodynamic (MHD) and the melting phenomenon effects.

Design/methodology/approach

The similarity variables are used to gain the similarity equations. These equations are solved via the bvp4c solver. The effects of several physical parameters on the flow and the thermal characteristics of the hybrid nanofluid are analysed and discussed. Later, the temporal stability analysis is used to determine the stability of the dual solutions obtained as time evolves.

Findings

Results show that two solutions are found for the limited range of the stretching/shrinking parameter λ, and then these solutions are terminated at λ=λc. The rise of the melting parameter Me from 0 to 2 contributes to enhance 109.63% of the local Nusselt number Rex-1/2Nux and 3.30% of the skin friction coefficient Rex1/2Cf. Contrarily, the values of Rex-1/2Nux and Rex1/2Cf decline by 25.04% and 5.58%, respectively, as the magnetic parameter Mg increases from 0 to 0.3. Additionally, Al2O3-Cu/water has the highest values of Rex1/2Cf and the lowest values of Rex-1/2Nux. Lastly, it is found that the first solution is physically stable as time evolves.

Originality/value

This paper considers the MHD stagnation point flow of a hybrid nanofluid over a shrinking surface with the melting phenomenon effects. Most importantly, it is shown that there exist dual solutions within a specific range of the physical parameters. Besides, the temporal stability of the solutions is also reported in this study. The finding can contribute to foresee the flow and thermal behaviours in industrial applications. Also, the suitable values of parameters can be determined to avoid misjudgement in flow and heat transfer analysis.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 30 September 2019

Lord Mensah, Divine Allotey, Emmanuel Sarpong-Kumankoma and William Coffie

This paper aims to test whether a debt threshold of public debt has any effect on economic growth in Africa.

Abstract

Purpose

This paper aims to test whether a debt threshold of public debt has any effect on economic growth in Africa.

Design/methodology/approach

The authors applied the panel autoregressive distributed models on 38 African countries with annual data from 1970 to 2015. It was established that the threshold and the trajectory of debt has an impact on economic growth.

Findings

Specifically, the authors found that public debt hampers economic growth when the depth is in the region of 20 to 80 per cent of GDP. Based on debt trajectory, this study established that increasing public debt beyond 50 to 80 per cent of GDP adversely affects economic growth in Africa. The study also finds that the persistent rise in debt also has adverse effect on economic growth in the African countries in the sample. It must be known to policymakers that the threshold of debt in developing countries, and for that matter African countries, are less than that of developed countries.

Practical implications

This study suggests threshold effects between 20 and 50 per cent; this should be a guide for policymakers in the accumulation of debt stock. Interestingly, the findings suggest some debt trajectory effect, which policymakers might consider by increasing efforts to reduce debt levels when they fall between 50 to 80 per cent of GDP. This implies that reducing such debt levels can help African countries increase their economic growth.

Originality/value

The study is unique because it seeks to add new evidence on the relationship between public debt and growth in the African region, by considering the impact of the persistent growth of public debt on economic growth.

Details

International Journal of Development Issues, vol. 19 no. 1
Type: Research Article
ISSN: 1446-8956

Keywords

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