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Article
Publication date: 14 July 2022

Mohamed Ouni, Fatih Selimefendigil, Besbes Hatem, Lioua Kolsi and Mohamed Omri

The purpose of this study is to analyze the impacts of combined utilization of multi-jet impinging cooling of nanofluids with magnetic field and porous layer on the cooling…

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Abstract

Purpose

The purpose of this study is to analyze the impacts of combined utilization of multi-jet impinging cooling of nanofluids with magnetic field and porous layer on the cooling performance, as effective cooling with impinging jets are obtained for various energy systems, including photovoltaic panels, electronic cooling and many other convective heat transfer applications.

Design/methodology/approach

Finite element method is used to explore the magnetic field effects with the inclusion of porous layer on the cooling performance efficiency of slot nanojet impingement system. Impacts of pertinent parameters such as Reynolds number (Re between 250 and 1,000), strength of magnetic field (Ha between 0 and 30), permeability of the porous layer (Da between 0.001 and 0.1) on the cooling performance for flat and wavy surface configurations are explored.

Findings

It is observed that the average Nusselt number (Nu) rises by about 17% and 20.4% for flat and wavy configuration while temperature drop of 4 K is obtained when Re is increased to 1,000 from 250. By using magnetic field at the highest strength, the average Nu rises by about 29% and 7% for flat and wavy cases. Porous layer permeability is an effective way of controlling the cooling performance while up to 44.5% variations in the average Nu is obtained by varying its value. An optimization routine is used to achieve the highest cooling rate while the optimum parameter set is obtained as (Re, Ha, Da, γ, sx) = (1,000, 30, 0.07558, 86.28, 2.585) for flat surface and (Re, Ha, Da, γ, sx) = (1,000, 30, 0.07558, 71.85, 2.329) for wavy surface configurations.

Originality/value

In thermal systems, cooling system design is important for thermal management of various energy systems, including fuel cells, photovoltaic panels, electronic cooling and many others. Impinging jets are considered as effective way of cooling because of its ability to give higher local heat transfer coefficients. This paper offers novel control tools, such as magnetic field, installation of porous layer and hybrid nano-liquid utilization for control of cooling performance with multiple impinging jets.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 33 no. 1
Type: Research Article
ISSN: 0961-5539

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Available. Content available

Abstract

Details

Journal of Financial Reporting and Accounting, vol. 20 no. 3/4
Type: Research Article
ISSN: 1985-2517

Available. Open Access. Open Access
Article
Publication date: 11 January 2024

Ameni Ghenimi, Hasna Chaibi and Mohamed Ali Omri

The aim of this study is to conduct a comparative analysis between Islamic and conventional banks in terms of whether Islamic banks was more or less resilient/risky than…

2504

Abstract

Purpose

The aim of this study is to conduct a comparative analysis between Islamic and conventional banks in terms of whether Islamic banks was more or less resilient/risky than conventional counterparts to the pandemic shock. It also examines the role of capital in improving the performance and stability within the two banking systems.

Design/methodology/approach

This study uses 82 banks from MENA (Middle East and North Africa) region for periods across 2011–2020, and employs a dynamic panel data approach to examine the resilience within both banking systems during the Covid-19 pandemic.

Findings

The results show that the Covid-19 pandemic has a negative impact on conventional banks' stability. However, Islamic banks performed better and were less risky than conventional ones. Banks with high-quality capital are more effective at controlling their risks and improving their performance during the pandemic.

Practical implications

The results offer important financial observations and policy implications to many stakeholders engaging with banks. Actually, the findings of this study facilitate to the stakeholders and bankers to have an alluded picture about determinants of risk and performance. The results can be used by bankers’ policy decision-makers to improve and enhance their consideration for risk management, taking into consideration the type of banking systems.

Originality/value

Compared to the various studies on the stability of Islamic and conventional banks, researchers have not sufficiently addressed the effect of the Covid-19 pandemic on risk and performance. Moreover, none of these studies has examined if Islamic banks was more or less resilient/risky than conventional counterparts to the pandemic shock. This leads the authors to identify the similarities and differences between two types of banks in the MENA region in a pandemic shock context.

Details

Arab Gulf Journal of Scientific Research, vol. 42 no. 4
Type: Research Article
ISSN: 1985-9899

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Article
Publication date: 17 March 2022

Lioua Kolsi, Fatih Selimefendigil and Mohamed Omri

The purpose of this study is to explore the phase change (PC) dynamics in a T-shaped ventilated cavity having multiple inlet and outlet ports during nanofluid convection with…

101

Abstract

Purpose

The purpose of this study is to explore the phase change (PC) dynamics in a T-shaped ventilated cavity having multiple inlet and outlet ports during nanofluid convection with phase change material (PCM) packed bed-installed system.

Design/Methodology/Approach

Finite element method was used to analyze the PC dynamics and phase completion time for encapsulated PCM within a vented cavity during the convection of nanoparticle loaded fluid. The study is performed for different Reynolds number of flow streams (Re1 and Re2 between 300 and 900), temperature difference (ΔT1 and ΔT2 between −5 and 10), aspect ratio of the cavity (between 0.5 and 1.5) and nanoparticle loading (between 0.02% and 0.1%).

Findings

It is observed that phase transition can be controlled by assigning different velocities and temperatures at the inlet ports of the T-shaped cavity. The PC becomes fast especially when the Re number and temperature of fluid in the port vary closer to the wall (second port). When the configurations with the lowest and highest Re number of the second port are considered up to 54.7% in reduction of complete phase transition time is obtained, while this amount is 78% when considering the lowest and highest inlet temperatures. The geometric factor which is the aspect ratio has also affected the flow field and PC dynamics. Up to 78% reduction in the phase transition time is obtained at the highest aspect ratio. Further improvements in the performance are achieved by using nanoparticles in the base fluid. The amounts in the phase transition time reduction are 8% and 10.5% at aspect ratio of 0.5 and 1.5 at the highest nanoparticle concentration.

Originality/Value

The thermofluid system and offered control mechanism for PC dynamics control can be considered for the design, optimization, further modeling and performance improvements of applications with PCM installed systems.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 11
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 16 November 2020

Ameni Ghenimi, Hasna Chaibi and Mohamed Ali Brahim Omri

This paper aims to identify and analyze the similarities and differences of the liquidity risk determinants within conventional and Islamic banks.

2667

Abstract

Purpose

This paper aims to identify and analyze the similarities and differences of the liquidity risk determinants within conventional and Islamic banks.

Design/methodology/approach

This study uses a dynamic panel data approach to examine the relationship between liquidity risk and a set of bank-specific and macroeconomic factors during 2005–2015, by selecting 27 Islamic banks and 49 conventional ones operating in the MENA region. More specifically, the dynamic two-step generalized method of moment estimator technique introduced by Arellano and Bond (1991) is applied.

Findings

The results suggest that the set of bank-specific variables influences the liquidity risk of both banking systems, while macroeconomic factors determine the liquidity risk of conventional banks. Islamic banks are not affected by macroeconomic determinants.

Practical implications

The research facilitates to the academicians, practitioners and bankers to have an alluded picture about liquidity risk determinants and their management. The findings can be used by bankers’ policy decision-makers to improve and enhance their consideration for liquidity risk management in both banking systems. Indeed, the study makes them aware to manage liquidity risk differently between conventional and Islamic banks, as the results reveal different liquidity risk determinants.

Originality/value

Compared to the abundant studies on the determinants of credit risk, researchers have not sufficiently addressed the factors influencing liquidity risk. Moreover, none of these few research studies has discussed and compared liquidity risk determinants within both banking systems operating in the Middle East and North Africa (MENA) region. This leads us to identify the similarities and differences between conventional and Islamic banks in the MENA region in respect of systematic and unsystematic determinants of the liquidity risk. The value is attributed to the increasing differentiation between Islamic and conventional banks. Islamic banks are characterized with a different liquidity structure distinguishing them from their conventional counterparts.

Details

International Journal of Law and Management, vol. 63 no. 1
Type: Research Article
ISSN: 1754-243X

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Article
Publication date: 3 September 2018

Henda Abdi, Henda Kacem and Mohamed Ali Brahim Omri

This paper aims to examine the factors influencing the extent of information disclosed on the companies’ websites in the Middle East region.

380

Abstract

Purpose

This paper aims to examine the factors influencing the extent of information disclosed on the companies’ websites in the Middle East region.

Design/methodology/approach

This study uses multiple regression models to examine the impact of some companies’ characteristics (company size, leverage, profitability, size of the audit firm, ownership concentration) on the extent of online disclosure. The study was conducted on 170 listed companies in seven countries (Saudi Arabia, Bahrain, the UAE, Jordan, Kuwait, Qatar and Turkey). The website content was analyzed during the period from September 2015 to December 2015.

Findings

The results reveal that the most important factors influencing the level of Web-based disclosure are company size, leverage and the size of the audit firm.

Practical implications

The results of the study will help regulators to formulate policies about Web-based disclosure as they offer insights into the characteristics of those companies which do and do not meet investors’ demands for online information. Thereby, the regulators might expect that the Middle East companies engage in the online reporting to be larger, have higher debt levels and audited by a big-four audit firm.

Originality/value

This study, added to the existing literature by analyzing seven countries in the Middle East region, allows having a clearer idea on the online disclosure in this region as a whole, which has not been examined before. In this paper, to assess the information’s disclosure on the website, the study has been interested in all of the information presented on the websites: financial and non-financial information.

Details

Journal of Financial Reporting and Accounting, vol. 16 no. 3
Type: Research Article
ISSN: 1985-2517

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Article
Publication date: 10 September 2021

Henda Kacem and Mohamed Ali Brahim Omri

This paper aims to investigate the question concerning whether tax incentives motivate companies to be socially responsible. This study, specifically, examines the impact of tax…

1003

Abstract

Purpose

This paper aims to investigate the question concerning whether tax incentives motivate companies to be socially responsible. This study, specifically, examines the impact of tax incentives for corporate social responsibility (CSR) on the societal practices of Tunisian companies.

Design/methodology/approach

This study uses multiple regression models to assess the effectiveness of tax incentives for companies to take responsible actions. The study was conducted on 71 Tunisian companies operating in different sectors.

Findings

The results reveal that there is a negative and significant association between tax incentives and CSR practices. Therefore, there is an inefficient use of these types of incentives.

Practical implications

The results of the study have important implications for investors and regulatory basis wishing to enhance CSR by giving tax incentives. Investment in social responsibility may improve the corporate culture and reduce the conflict in companies.

Originality/value

The theoretical contributions relate mainly to the originality of the conceptual model developed, to the literature review and to the theoretical foundations mobilized. In fact, the originality of this research is justified by the scarcity of previous study dealing with the relationship between tax incentives and CSR. Thus, to the best of the authors’ knowledge, this study is one of the first to investigate the impact of tax incentives for CSR on CSR practices.

Details

Journal of Financial Reporting and Accounting, vol. 20 no. 3/4
Type: Research Article
ISSN: 1985-2517

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Article
Publication date: 27 May 2020

Henda Abdi and Mohamed Ali Brahim Omri

The aim of this study is to investigate the effect of web - based disclosure on the cost of debt for the MENA region setting.

429

Abstract

Purpose

The aim of this study is to investigate the effect of web - based disclosure on the cost of debt for the MENA region setting.

Design/methodology/approach

The sample of this paper consists of 237 MENA listed non-financial companies for the year 2017. Multiple regression models were used to examine the impact of online disclosure on the cost of debt. Content analysis is used to measure the extent of web-based disclosure.

Findings

The results reveal that there is a negative and significant association between the web-based disclosure and the company’s cost of debt. These results support the hypothesis of the economic utility of the information disclosed on the website for creditors in this region.

Practical implications

The results of the study have important implications for managers in the MENA region. It is necessary for managers to improve the company’s transparency through web-based disclosure. The companies must benefit from the different technologies offered by the Internet in order to offer to the creditors unlimited access to up to date information. In fact, web-based disclosure may mitigate the information asymmetry, the uncertainty of creditors and, consequently, reduces the cost of debt. 10; 10;Moreover, the results of the study provide empirical evidence for the advantages of voluntary web-based disclosure. The results highlight the importance to companies and regulators of understanding the benefits of using the website as a means of information disclosure. The regulators in MENA countries can rely on these results to establish suitable policies to improve the quality of web-based disclosure. The regulators need also to put in rules in relation to the online disclosure. In fact, an understanding of web-based disclosure is important for regulators and companies. Given the positive effect of online disclosure (the reduction of the cost of debt), knowledge about the economic consequences of web-based disclosure would enable companies in the MENA region to optimize their online disclosure policies.

Originality/value

This study, added to the existing literature by examining the consequences of online disclosure practices in MENA countries. Most previous studies conducted in this region were limited to analyzing the determinants of the company’s web-based disclosure. This paper would extend the literature on the online disclosure practices by investigating the association between these practices and the cost of debt in a developing economics: the MENA region. Previous studies were limited to testing this association only in developed countries.

Details

Journal of Financial Reporting and Accounting, vol. 18 no. 3
Type: Research Article
ISSN: 1985-2517

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Article
Publication date: 9 January 2009

Mohamed Omri and Nicolas Galanis

The purpose of this paper is to evaluate the capacity of two equation turbulence models to reproduce mean and fluctuating quantities in the case of both natural convection and…

652

Abstract

Purpose

The purpose of this paper is to evaluate the capacity of two equation turbulence models to reproduce mean and fluctuating quantities in the case of both natural convection and isothermal flows.

Design/methodology/approach

Numerical predictions of mean velocity profiles, air and wall temperatures as well as turbulent kinetic energy by three different two equation models (standard kε, renormalisation group kε and shear‐stress transport‐kω) are compared with corresponding experimental values.

Findings

The prediction of mean velocities and temperatures is in all cases satisfactory. On the other hand, the prediction of turbulent quantities is less precise.

Originality/value

The three models under consideration in this paper can be used for engineering applications such as HVAC calculations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 19 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 2 March 2010

Faten Hakim and Mohamed Ali Omri

The purpose of this paper is to examine the relationship between information asymmetry and the quality of the external audit in the Tunisian capital market.

3209

Abstract

Purpose

The purpose of this paper is to examine the relationship between information asymmetry and the quality of the external audit in the Tunisian capital market.

Design/methodology/approach

The paper uses panel data methodology.

Findings

The results show that the bid‐ask, a market‐based measure of information asymmetry, is negatively related to the employment of an industry specialist and big auditors; and positively related to audit firm tenure. However, further tests refine those conclusions, in that the positive association between tenure and bids‐ask spread differs between specialist and non‐specialist auditors and between Big 4 and non‐Big 4 auditors. Specifically, the paper finds that bid‐ask spreads is increasing in tenure for clients of non‐specialist and clients of non‐Big 4.

Research limitations/implications

The difficulties in specifying correct models for determining the audit quality, the research analyze the auditor's quality such as big auditor, tenure, and specialist. The paper leaves this and other issues for future research.

Originality/value

Analyzing the effect of auditor's quality on information asymmetry and bid‐ask spreads is an emerging economy such as Tunisia is very appealing because earnings quality is the most important quality investors look for. And this research makes a link between two important areas of auditing and finance.

Details

International Journal of Accounting & Information Management, vol. 18 no. 1
Type: Research Article
ISSN: 1834-7649

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