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The purpose of this paper is to present a numerical analysis of the flow and heat transfer in a tube with a wire coil insert. A second law analysis of the results is accounted for, in order to assess the local and overall entropy generation in relation with the increased pressure drop and convective heat transfer. A wire coil with p/D=1.25 and e/D=0.076 is selected as insert device. A Reynolds number range between 100 and 1,000 is investigated, which corresponds to the typical operating regimes in the risers of liquid solar collectors. Different wall heat fluxes and inclination angles allow to analyze the potential impact of mixed convection in the presence of tube inserts.

Three-dimensional numerical simulations are performed using a finite-volume solver, assuming laminar flow conditions. Pure water and a mixture of water and propylene-glycol (20 percent) are used as working fluids, with temperature-dependent properties. Fanning friction factor, Nusselt number and local entropy generation results are obtained in the fully developed region.

The friction factor results are successfully compared with a well-known experimental correlation for wire coil inserts. The earlier onset of transition is devised at Re > 300. Nusselt number augmentations between 2.5- and 6-fold are reported with respect to the smooth tube. The mixed convection regime encountered in the smooth tube for the operating conditions investigated is canceled in the wire coiled tube, owing to the opposed effect of the swirl flow induced and the bouyancy forces. Frictional, heat transfer and overall entropy generation rates are computed locally in the fully developed region, allowing to relate these results with the flow structures in the mixed convection smooth tube and in the wire coiled tube. A threefold decrease in the entropy generation rate is reported for tubes with wire coil inserts.

An holistic understanding of the heat transfer enhancement in tubes with wire coil inserts is provided through the analysis of the flow pattern, Fanning friction factor, Nusselt number and local entropy generation rates. The reduced entropy generation in the enhanced tube serves as a performance criteria to confirm the positive effect of wire coil inserts in heat transfer for the operating regime under investigation, in spite of the increased pressure drop.

The specific criteria to the microstructure of emerging markets such as low liquidity, very pronounced asymmetric information, and high volatility affect the risk market. Previous researchers have concluded that the calculation methods of the Value‐at‐Risk (VaR) adopted in developed markets are poorly adapted to the specific structure of emerging markets. The purpose of this paper is to see what these specific criteria of emerging markets are and whether these criteria have any impact on market risk and hedging capital. A second purpose it to see if practitioners should adjust the tools of risk measurement to the specifications of emerging markets and how the Value‐at‐Risk (VaR) should be adjusted.

The paper asks what are the specific criteria to the microstructure of emerging markets? Should we adjust the tools of risk measurement to these specifications? How do we adjust the Value‐at‐Risk (VaR)?

The paper demonstrated a market improvement in the performance of adjusted VaR. Indeed, models for measuring the VaR adjusted to liquidity and to asymmetry of information are accepted by the tests of backtesting. The term of average error has decreased.

This improvement of adjusted VaR in the performance of measuring risk implies a better estimation of the capital allocated to cover market risk.

The results from this empirical study offer an alternative approach adapted to the specific structure of emerging markets and a better estimation of the capital allocated to cover market risk.

Although many studies have been conducted on the nanofluid flow in microtubes, this paper, for the first time, aims to investigate the effects of nanoparticle diameter and concentration on the velocity and temperature fields of turbulent non-Newtonian Carboxymethylcellulose (CMC)/copper oxide (CuO) nanofluid in a three-dimensional microtube. Modeling has been done using low- and high-Reynolds turbulent models. CMC/CuO was modeled using power law non-Newtonian model. The authors obtained interesting results, which can be helpful for engineers and researchers that work on cooling of electronic devices such as LED, VLSI circuits and MEMS, as well as similar devices.

Present numerical simulation was performed with finite volume method. For obtaining higher accuracy in the numerical solving procedure, second-order upwind discretization and SIMPLEC algorithm were used. For all Reynolds numbers and volume fractions, a maximum residual of 10⁻⁶ is considered for saving computer memory usage and the time for the numerical solving procedure.

In constant Reynolds number and by decreasing the diameter of nanoparticles, the convection heat transfer coefficient increases. In Reynolds numbers of 2,500, 4,500 and 6,000, using nanoparticles with the diameter of 25 nm compared with 50 nm causes 0.34 per cent enhancement of convection heat transfer coefficient and Nusselt number. Also, in Reynolds number of 2,500, by increasing the concentration of nanoparticles with the diameter of 25 nm from 0.5 to 1 per cent, the average Nusselt number increases by almost 0.1 per cent. Similarly, In Reynolds numbers of 4,500 and 6,000, the average Nusselt number increases by 1.8 per cent.

The numerical simulation was carried out for three nanoparticle diameters of 25, 50 and 100 nm with three Reynolds numbers of 2,500, 4,500 and 6,000. Constant heat flux is on the channel, and the inlet fluid becomes heated and exists from it.

The authors obtained interesting results, which can be helpful for engineers and researchers that work on cooling of electronic devices such as LED, VLSI circuits and MEMS, as well as similar devices.

This manuscript is an original work, has not been published and is not under consideration for publication elsewhere. About the competing interests, the authors declare that they have no competing interests.

The purpose of this study is three-dimensional flow and heat transfer investigation of water/Al₂O₃ nanofluid inside a microchannel with different cross-sections in two-phase mode.

The effect of microchannel walls geometry (trapezoidal, sinusoidal and stepped microchannels) on flow characteristics and also changing circular cross section to trapezoidal cross section in laminar flow at Reynolds numbers of 50, 100, 300 and 600 were investigated. In this study, two-phase water/Al₂O₃ nanofluid is simulated by the mixture model, and the effect of volume fraction of nanoparticles on performance evaluation criterion (PEC) is studied. The accuracy of obtained results was compared with the experimental and numerical results of other similar papers.

Results show that in flow at lower Reynolds numbers, sinusoidal walls create a pressure drop in pure water flow which improves heat transfer to obtain PEC < 1. However, in sinusoidal and stepped microchannel with higher Reynolds numbers, PEC > 1. Results showed that the stepped microchannel had higher pressure drop, better thermal performance and higher PEC than other microchannels.

Review of previous studies showed that existing papers have not compared and investigated nanofluid in a two-phase mode in inhomogeneous circular, stepped and sinusoidal cross and trapezoidal cross-sections by considering the effect of changing channel shape, which is the aim of the present paper.

The perception of Islamic finance by its various stakeholders is not always reconcilable. Its foundations and attributes are subject to a plurality of perceptions making it almost impossible to reach a consensus about them. This paper aims to understand the perception of Islamic finance by bank employees in Cameroon.

This research follows the interpretativist paradigm and is qualitative and exploratory in nature. The data are collected through semi-structured face-to-face interviews with bank employees, mainly branch managers. These interview data are analysed using the thematic analysis method.

Bank employees in Cameroon perceive Islamic finance as a finance that: targets everyone, regardless of religion, but Muslims first (Islamic finance is both inclusive and exclusive); offers original products and services; has a religious anchor that may hinder non-Muslim economic agents; has many advantages, mainly for financial institutions, and some limitations for financial institutions and their customers; is full of opportunities for its stakeholders; and is not yet fully practiced in Cameroon.

This study mobilises a qualitative approach, provides new insights into the research on the perception of Islamic finance and reaches a consensus on the perception of certain aspects and attributes of Islamic finance, namely, for the perception of the target and the Shariah compliance of Islamic finance. Furthermore, this study is a pioneering effort to understand bank employees’ perception of Islamic finance in non-Islamic and developing countries where Islamic finance is underdeveloped.

The purpose of this paper is to investigate whether higher disclosure levels at both Islamic and conventional banks are associated with higher stock price volatility in the member countries of the Gulf Cooperation Council (GCC).

To do this, the authors build a disclosure index (DI) for both types of banks and compare their transparency levels. After that, the authors evaluate the relationship between disclosure and stock price volatility for both conventional and Islamic banks (IBs) and include macro- and bank-level control factors to isolate the effect of disclosure from potentially confounding influences by employing panel data.

The author find that the significance of the DI on stock price volatility is economically negligible at both types of banks, suggesting that injecting more information into markets would raise stock price volatility only slightly and hence will not have much economically significant effect on stock price volatility in our sample countries. The authors discuss the policy implications of the findings.

The study fills the gap in the literature and assists in formulating appropriate regulation policies for corporate governance disclosure requirements. To the best of our knowledge, this is the first empirical study to investigate the impact of disclosure on reducing stock price volatility in the dual banking system of the GCC countries.

This study explores the practical application of the Shariah screening process and how it could be enhanced by converging the same with the ethical screening of stocks.

This study adopts a qualitative research methodology by combining the qualitative descriptive approach and content analysis.

The findings of this research suggest that there is scope to converge ethical screening of stocks with Shariah Screening as the lex loci applicable to Shariah screening is derived from Shariah, which considers ethics as part of determining its rules.

The data from this study reveal several practical applications, the ultimate goal of which is to help the policymakers and stakeholders understand the relevance of the Shariah screening of stocks and get a streamlined screening process, paving the way to enhance the same using ethical screening criteria to develop its function to become much more relevant irrespective of the denomination of faiths.

This is original research, which is expected to contribute to understanding the extent to which Shariah screening can be enhanced by integrating the ethical stock screening dimension to it.

A review of relevant literature supported the need to examine the nature of the relationships (if any) between visionary leadership, continual improvement and product quality. This study examined the relationship between visionary leadership and product quality and investigated the mediating role of continual improvement in the relationship between visionary leadership and product quality.

Visionary leadership, continual improvement and product quality were measured through a questionnaire developed based on a theoretical framework derived from the literature and distributed to quality assurance managers in small and medium-sized companies in the engineering, electrical and information technology sectors in Jordan.

The results indicated that the levels of visionary leadership, continual improvement and product quality are good and more from the perspective of quality assurance managers in these companies. The results also indicated that there is a positive, statistically significant relationship between visionary leadership and continual improvement and between continual improvement and product quality. Moreover, the results indicated that the relationship between visionary leadership and product quality is partially mediated by continual improvement. This indicates that there is a direct, positive and statistically significant relationship between visionary leadership and product quality.

To the author’s knowledge, this is the first study that examined the relationship between visionary leadership, continual improvement and product quality and investigated the mediating role of continual improvement in the relationship between visionary leadership and product quality. This study concluded that visionary leadership is the driver of all improvement initiatives and activities, which in turn improve the final products. The study contributes to the literature by revealing that visionary leadership leads to continual improvement and thus product quality, supporting the sequential relationship between them. Accordingly, the study provides useful theoretical insights and practical implications.

There is no uniform methodology adopted worldwide for Shariah equity screening. The purpose of this research paper is to suggest reforms required to improve Shariah screening methodologies used for equities using Dow Jones Islamic Market Index, which is the world’s first such methodology adopted.

This research uses a qualitative research methodology that goes beyond analysing secondary data on the subject matter. It includes conducting semi-structured interviews with selected subject matter experts to gain insights into the practical issues associated with existing Shariah screening methodologies. The aim is to identify areas for potential reforms that can be implemented in the future. By combining secondary data analysis with first-hand perspectives from experts, this research provides a comprehensive understanding of the challenges and opportunities in Shariah screening, contributing to the development of practical and effective reforms.

The study recommends the inclusion of additional filters in Shariah screening methodologies to promote stocks that are not only Shariah-compliant but also socially responsible. It suggests that while a certain level of Shariah non-compliance threshold may be tolerated during the initial screening stage, over time, this accepted threshold should gradually decrease. The ultimate goal is to achieve 0% thresholds for Shariah-compliant equities. By advocating for stricter criteria and a progressive reduction in non-compliance tolerance, the study highlights the importance of continuously improving and refining Shariah screening practices to ensure higher levels of compliance and alignment with Shariah principles.

It is anticipated that the findings of this research provides original insights and contributions to existing knowledge. It offers novel perspectives, innovative approaches and solutions to address specific areas in need of reform. By focusing on enhancing the effectiveness and standardisation of Shariah-compliant investment practices, the research brings fresh perspectives and adds value to the field. Its unique contribution lies in identifying and addressing emerging challenges and proposing improvements in Shariah screening methodologies.

This paper aims to investigate to what extent hybrid differential evolution (DE) algorithms can be successful in solving the optimal camera placement problem.

This problem is stated as a unicost set covering problem (USCP) and 18 problem instances are defined according to practical operational needs. Three methods are selected from the literature to solve these instances: a CPLEX solver, greedy algorithm and row weighting local search (RWLS). Then, it is proposed to hybridize these algorithms with two hybrid DE approaches designed for combinatorial optimization problems. The first one is a set-based approach (DEset) from the literature. The second one is a new similarity-based approach (DEsim) that takes advantage of the geometric characteristics of a camera to find better solutions.

The experimental study highlights that RWLS and DEsim-CPLEX are the best proposed algorithms. Both easily outperform CPLEX, and it turns out that RWLS performs better on one class of problem instances, whereas DEsim-CPLEX performs better on another class, depending on the minimal resolution needed in practice.

Up to now, the efficiency of RWLS and the DEset approach has been investigated only for a few problems. Thus, the first contribution is to apply these methods for the first time in the context of camera placement. Moreover, new hybrid DE algorithms are proposed to solve the optimal camera placement problem when stated as a USCP. The second main contribution is the design of the DEsim approach that uses the distance between camera locations to fully benefit from the DE mutation scheme.