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The purpose of this paper is to explore the novel aspects of activation energy in the nonlinearly convective flow of Walter-B nanofluid in view of Cattaneo–Christov double-diffusion model over a permeable stretched sheet. Features of nonlinear thermal radiation, dual stratification, non-uniform heat generation/absorption, MHD and binary chemical reaction are also evaluated for present flow problem. Walter-B nanomaterial model is employed to describe the significant slip mechanism of Brownian and thermophoresis diffusions. Generalized Fourier’s and Fick’s laws are examined through Cattaneo–Christov double-diffusion model. Modified Arrhenius formula for activation energy is also implemented.

Several techniques are employed for solving nonlinear differential equations. The authors have used a homotopy technique (HAM) for our nonlinear problem to get convergent solutions. The homotopy analysis method (HAM) is a semi-analytical technique to solve nonlinear coupled ordinary/partial differential equations. The capability of the HAM to naturally display convergence of the series solution is unusual in analytical and semi-analytic approaches to nonlinear partial differential equations. This analytical method has the following great advantages over other techniques:

• It provides a series solution without depending upon small/large physical parameters and applicable for not only weakly but also strongly nonlinear problems.

• It guarantees the convergence of series solutions for nonlinear problems.

• It provides us a great choice to select the base function of the required solution and the corresponding auxiliary linear operator of the homotopy.

It provides a series solution without depending upon small/large physical parameters and applicable for not only weakly but also strongly nonlinear problems.

It guarantees the convergence of series solutions for nonlinear problems.

It provides us a great choice to select the base function of the required solution and the corresponding auxiliary linear operator of the homotopy.

Brief mathematical description of HAM technique (Liao, 2012; Mabood et al., 2016) is as follows. For a general nonlinear equation:

where N denotes a nonlinear operator, x the independent variables and u(x) is an unknown function, respectively. By means of generalizing the traditional homotopy method, Liao (1992) creates the so-called zero-order deformation equation:

here q∈[0, 1] is the embedding parameter, H(x) ≠ 0 is an auxiliary function, h(≠ 0) is a nonzero parameter, L is an auxiliary linear operator, u_o(x) is an initial guess of u(x) and u ˆ ( x ; q ) is an unknown function, respectively. It is significant that one has great freedom to choose auxiliary things in HAM. Noticeably, when q=0 and q=1, following holds:

Expanding u ˆ ( x ; q ) in Taylor series with respect to (q), we have:

If the initial guess, the auxiliary linear operator, the auxiliary h and the auxiliary function are selected properly, then the series (4) converges at q=1, then we have:

By defining a vector u → = ( u o ( x ) , u 1 ( x ) , u 2 ( x ) , … , u n ( x ) ) , and differentiating Equation (2) m-times with respect to (q) and then setting q=0, we obtain the mth-order deformation equation:

where:

Applying L⁻¹ on both sides of Equation (6), we get:

In this way, we obtain u_m for m ⩾ 1, at mth-order, we have:

It is evident from obtained results that the nanoparticle concentration field is directly proportional to the chemical reaction with activation energy. Additionally, both temperature and concentration distributions are declining functions of thermal and solutal stratification parameters (P₁) and (P₂), respectively. Moreover, temperature Θ(Ω₁) enhances for greater values of Brownian motion parameter (N_b), non-uniform heat source/sink parameter (B₁) and thermophoresis factor (N_t). Reverse behavior of concentration ϒ(Ω₁) field is remarked in view of (N_b) and (N_t). Graphs and tables are also constructed to analyze the effect of different flow parameters on skin friction coefficient, local Nusselt number, Sherwood numbers, velocity, temperature and concentration fields.

The novelty of the present problem is to inspect the Arrhenius activation energy phenomena for viscoelastic Walter-B nanofluid model with additional features of nonlinear thermal radiation, non-uniform heat generation/absorption, nonlinear mixed convection, thermal and solutal stratification. The novel aspect of binary chemical reaction is analyzed to characterize the impact of activation energy in the presence of Cattaneo–Christov double-diffusion model. The mathematical model of Buongiorno is employed to incorporate Brownian motion and thermophoresis effects due to nanoparticles.

This study aims to compare capital structure determinants' effect on the leverage levels of Shariah-compliant (SC) and noncompliant (NC) firms in Pakistan. This study also estimates and compares the capital structure adjustment speed for both firm types.

Based on the Karachi Meezan Index screening criterion, a balanced panel of 117 SC and 68 NC firms listed on the Pakistan Stock Exchange from 2008 to 2018 was constituted. This study used the generalized method of moments to identify the significant determinants of capital structure and estimate the speed of adjustment. In addition, the F-test was used to check whether the effect of the determinants on the leverage is same for SC and non-SC firms.

The authors found that different determinants affect both firm types' leverage levels (book and market) differently. The authors also found that the adjustment speed of SC firms toward their target leverage ratio is slower than their NC peers. Lastly, significant variation was observed in the results under different screening criteria.

This study fills the literature gap by providing a comprehensive comparison of the capital structure decisions of the SC and non-SC firms. Because this study is limited to Pakistan, generalizability would be an issue.

This study will guide the management of SC and non-SC firms about which factors are reliably important in choosing their capital structure. The findings also call for bringing harmony in the different Shariah screening criteria being in practice.

To the best of the authors’ knowledge, this is the first comparative study that identifies the significant capital structure determinants for SC and NC firms and investigates their effect on the leverage of both firm types. By testing joint hypotheses of same relationship, this study seeks to determine if, because of Shariah restrictions, the capital structure determinants of SC firms are similar to NC firms or they exhibit different behavior. The authors also repeat their analysis using other prominent screening criteria to assess the consistency of their results.

In this paper some characterizations for the existence of warped product pointwise semi-slant submanifolds of cosymplectic space forms are obtained. Moreover, a sharp estimate for the squared norm of the second fundamental form is investigated, the equality case is also discussed. By the application of derived inequality, we compute an expression for Dirichlet energy of the involved warping function. Finally, we also proved some classifications for these warped product submanifolds in terms of Ricci solitons and Ricci curvature. A non-trivial example of these warped product submanifolds is provided.

The purpose of the research is to analyze the impact of world uncertainty and pandemic uncertainty on Islamic financial markets. For representing Islamic financial markets four different Islamic indices (DJ Islamic index, DJ Islamic Asia–Pacific index, DJ Islamic-Europe index and DJ Islamic-US) are taken.

The study employs quantile-on-quantile regression approach to see the overall dependence structure of variables based on quarterly data ranging from 1996Q1 to 2020Q4. This technique considers how quantiles of world uncertainty and pandemic uncertainty asymmetrically affect the quantiles of Islamic stocks by giving an appropriate framework to apprehend the overall dependence structure.

The findings of the study confirm a strong negative impact of world uncertainty and world pandemic uncertainty on regional Islamic stock indices but the strength of the relationship varies according to economic conditions and across the regions. However, the world pandemic effect remains the same and does not change. Conversely, pandemic uncertainty has a larger effect on Islamic indices as compared to world uncertainty.

Our findings have significant implications for investors and policymakers to take proper steps before any uncertainty arise. A coalition of the central bank, government officials and investment bank regulators would be needed to tackle this challenge of uncertainty.

To the best of the authors' knowledge, none of the current works has considered the asymmetric impact of world and pandemic uncertainties on Islamic stock markets at both the bottom and upper quantiles of the distribution of data.

Jubail Industrial City is one of the largest industrial centers in the Middle East, offering potential opportunities for renewable energy generation. This research paper presents a comprehensive analysis of the wind resources in Jubail Industrial City and proposes the design of a smart grid-connected wind farm for this strategic location.

The study used wind data collected at three different heights above ground level – 10, 50 and 90 m – over four years from 2017 to 2020. Key parameters, such as average wind speeds (WS), predominant wind direction, Weibull shape, scale parameters and wind power density (WPD), were analyzed. The study used Windographer, an exclusive software program designed to evaluate wind resources.

The average WS at the respective heights were 3.07, 4.29 and 4.58 m/s. The predominant wind direction was from the north-west. The Weibull shape parameter (k) at the three heights was 1.77, 2.15 and 2.01, while the scale parameter (c) was 3.36, 4.88 and 5.33 m/s. The WPD values at different heights were 17.9, 48.8 and 59.3 W/m², respectively.

The findings suggest that Jubail Industrial City possesses favorable wind resources for wind energy generation. The proposed smart grid-connected wind farm design demonstrates the feasibility of harnessing wind power in the region, contributing to sustainable energy production and economic benefits.

The purpose of this paper is to investigate whether banks’ environmental, social and governance (ESG) initiatives increase or decrease banks’ efficiency.

The sample used includes all listed banks in Saudi Arabia over the years 2016–2021. The authors performed different methods, including data envelopment analysis (DEA), ordinary least squares (OLS) and quantile regressions.

The OLS regression results show a negative linkage between ESG and banks’ efficiency. Further, the quantile regression analysis indicates that the ESG effect on banks' efficiency is negative across different quantiles. However, the DEA method shows that the DEA-generated scores for Banks’ efficiency are higher for ESG-adjusted scores in comparison to efficiency scores without incorporating ESG. Further, the comparison of the DEA-generated efficiency scores, over the sample period, of adjusted ESG banks still suffers from decreasing in their efficiency over the years. Concerning existing theory, the results are consistent with the stakeholders and the resource-based theories postulating that banks' ESG practices are ethical commitments and enable firms to gain competitive advantage and increase their reputation among stakeholders.

The findings of this study offer important implications for regulators and bankers. Policymakers and bank regulators should make collective efforts to encourage financial institutions to adopt green finance initiatives to create an efficient financial system capable of counteracting risks from the external environment and stimulating economic growth. Banks’ managers should be aware that ESG initiatives serve society and the environment and offer a positive influence on banks’ efficiency.

To the best of the authors’ knowledge, this is the first study to explore the influence of ESG activities on banks' efficiency using DEA for banks in Saudi Arabia.

The purpose of this study is to critically evaluate how conventional and Islamic banks trade off risk, efficiency and financial performance in their business models, to investigate how patterns of risk and efficiency vary between conventional and Islamic banks and to critically evaluate how the profitability of conventional and Islamic banks varies following the financial crisis.

This study uses univariate and multivariate statistical techniques by investigating 12 Islamic banks and 34 conventional banks operating in the Gulf Cooperation Council (GCC) region has been studied over the period 2011–2018.

The results suggest that Islamic and conventional banks differ not in the levels of efficiency, risk and profitability, but rather in how risk and efficiency influence banks’ financial performance. Islamic banks are found to be less influenced by the adverse effects of credit risk, which is consistent with the risk-sharing nature of Islamic financing. However, the results only hold for return on assets (ROA) and return on equity (ROE) while the net interest margin is observed to be negatively influenced by credit risk. Lower cost-income efficiency is also found to boost ROA and ROE of Islamic banks which could be attributed to a larger share of non-interest revenues due to Sharīʿah-compliance.

From a theoretical point of view, this study helps to understand the risk, efficiency and financial performance of Islamic banks in comparison with conventional banks.

The results of this study can serve bank managers, regulators and shareholders. Policymakers should encourage a more risk-sharing structure of Islamic financing as it brings less adverse effects of credit risk and increases income sustainability for Islamic banks. The present study may help bank managers to improve the financial performance of their firms by controlling risk and efficiency. The study results also have implications for shareholders and depositors of Islamic and conventional banks as they should have a predetermined position about the level of credit risk and efficiency in each banking system.

The foremost contribution is that this is one of the few studies to compare risk, efficiency and financial performance of Islamic and conventional banks in the GCC region. By using the latest data, this paper hopes that the findings will be more relevant than previous studies to the current situation of the banking industry in the region.

This study aims to extend the literature by simultaneously investigating the relationship between risk, efficiency and capital in the Gulf Cooperation Council (GCC) dual banking system.

The study employs the simultaneous-equation modeling technique with a three-stage least square estimator on 60 listed GCC commercial banks from 2005 through 2018.

Although GCC Islamic banks are more capitalized and liquid, they are riskier and less efficient than GCC conventional banks. Moreover, a higher level of capital reduces the insolvency and credit risk of GCC banks for both types of banks. However, it enhances the cost efficiency of GCC conventional banks only. GCC conventional banks also exhibit skimping behavior, while for GCC Islamic banks, cost efficiency is negatively associated with bank risk. This implies that the risk-taking behavior in Islamic banks is prompted by the incentives of the shareholders following the risk-sharing nature of Islamic banking.

This study differs from previous studies in many aspects. First, it relies on a recent long data set that covers the implementation of the accords of Basel II (introduced in 2004) and Basel III (introduced in 2010). Second, it estimates the efficiency of GCC banks based on separate frontiers for Islamic and conventional banks, ensuring the robustness of the results. In conclusion, to the best of the author's knowledge, this is the first study to investigate the intertemporal relationship between risk, efficiency and capital in the GCC dual banking industry.

This study aims to provide a comprehensive bibliometric investigation of the antecedents to financial stability in Islamic banking, a transition economy with a volatile stock market focusing on banks following the Shariah approach.

The data for this analysis was extracted from the Scopus database, which combines a comprehensively crafted abstract and citation database with augmented data and linked scholarly works across various disciplines. It quickly finds relevant research and provides access to reliable data and analytical tools. This study deploys “bibliometrix 3.0,” a biblioshiny R-package for influential structure and the VOS viewer for intellectual structure.

The investigation’s main findings revealed that 1,910 documents were published from 1987 to 2022. Published manuscripts received 39,050 citations, with an average of 10.18 citations per year. However, the instructed empirical research was experienced during 2009 and 2020, while earlier periods (1987–2008) were relatively inactive where banking was considered protective in the presence of BASEL-II capital accords regulations. While the International Journal of Bank Market has been at the top of the list to publish articles related to the area under investigation, the Journal of Banking and Finance is ranked one of the most cited articles. Malaysia has been at the top of the list of countries to research Islamic Sharia compliance principles in the banking industry, and International Islamic University Malaysia has produced enough evidence in this regard. The intellectual structure provided essential foundations for future research, and the bibliometric coupling approach was used.

While most of the banking research has been conducted to determine the banking business efficiency, risk and profitability, little focus is given to financial stability and that too concerning the Islamic banks. Therefore, researchers need to investigate this horizon from an Islamic banking point of view and focus on key issues that discriminate between Islamic and conventional banks in determining their stability level.

Briefly, to the best of the authors’ knowledge, this study would be the first to provide bibliometric information about financial stability keeping in view the sample data from banks with the Shariah approach. Furthermore, the proven analysis demonstrates a novel contribution that financially stable Islamic banks might strengthen the financial industry and overall economy.

This paper aims to investigate a fundamental research question of whether the Islamic banking business model makes corporate earnings more uncertain. This question arises because prior research shows that Islamic banks do well in loan performance but incur more operational costs than conventional banks, indicating the systemic limitation of Islamic banks in business risk management.

The study used a sample of banks to conduct the panel regression analysis with 15 years of data for 532 banks (129 Islamic and 403 conventional) from 23 Muslim countries across the world. The authors estimate earnings uncertainty in two ways: the spread and standard deviation of the country-adjusted return over the sample period and applied the difference-in-difference approach interacting cost to income ratio with the Islamic bank dummy, checking if Islamic bank’s high operational costs contribute to more earning uncertainty.

Islamic banks’ returns on assets are significantly more uncertain than conventional banks due to higher operational costs. Consistent with earlier evidence, the study also finds that Islamic banks generally have fewer nonperforming loans than conventional banks. The authors conclude that Islamic banks trade-off between reducing credit risk and escalating business risk.

This study documents that the Islamic banking model helps build a safer asset portfolio but gives rise to the uncertainty of corporate earnings. Therefore, the choice between Islamic and conventional banking models involves a trade-off between credit and business risks. It is a new finding that we add to the literature body on Islamic finance.