F. Asllanaj, G. Jeandel and J.R. Roche
A new way of solving the steady‐state coupled radiative‐conductive problem in semi‐transparent media is proposed. An angular discretization technique is applied in order to…
Abstract
A new way of solving the steady‐state coupled radiative‐conductive problem in semi‐transparent media is proposed. An angular discretization technique is applied in order to express the radiative transfer equation (RTE) in an inhomogeneous system of linear differential equations associated with Dirichlet boundary conditions. The system is solved by a direct method, after diagonalizing the characteristic matrix of the medium. The RTE is coupled with the nonlinear heat conduction equation. A simulation of a real semi‐transparent medium composed of silica fibers is illustrated. Comparison with results of other methods validates the new model. Moreover, the general scheme is easy to code and fast. The algorithm proved to be robust and stable.
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H. Amiri, S.H. Mansouri and P.J. Coelho
The solution of radiative heat transfer problems in participating media is often obtained using the standard discrete ordinates method (SDOM). This method produces anomalies…
Abstract
Purpose
The solution of radiative heat transfer problems in participating media is often obtained using the standard discrete ordinates method (SDOM). This method produces anomalies caused by ray effects if radiative boundary conditions have discontinuities or abrupt changes. Ray effects may be mitigated using the modified discrete ordinates method (MDOM), which is based on superposition of the solutions obtained by considering separately radiation from the walls and radiation from the medium. The purpose of this paper is to study the role of ray effects in combined conduction‐radiation problems and investigate the superiority of the MDOM over SDOM.
Design/methodology/approach
The MDOM has been used to calculate radiative heat transfer in irregular geometries using body‐fitted coordinates. Here, the blocked‐off region concept, originally developed in computational fluid dynamics, is used along with the finite volume method and SDOM or MDOM to solve combined conduction‐radiation heat transport problems in irregular geometries. Enclosures with an absorbing, emitting and isotropically or anisotropically scattering medium are analyzed.
Findings
The results confirm the capability of the MDOM to minimize the anomalies due to ray effects in combined heat transfer problems, and demonstrate that MDOM is more computationally efficient than SDOM.
Originality/value
The paper demonstrates the application of MDOM to combined conduction‐radiation heat transfer problems in irregular geometries using blocked‐off method.
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Aleksey V. Nenarokomov, Leonid A. Dombrovsky, Irina V. Krainova, Oleg M. Alifanov and Sergey A. Budnik
The purpose of this study is to optimize multilayer vacuum thermal insulation (MLI) of modern high-weight spacecrafts. An adequate mathematical simulation of heat transfer in the…
Abstract
Purpose
The purpose of this study is to optimize multilayer vacuum thermal insulation (MLI) of modern high-weight spacecrafts. An adequate mathematical simulation of heat transfer in the MLI is impossible if there is no available information on the main insulation properties.
Design/methodology/approach
The results of experiments in thermo-vacuum facilities are used to re-estimate some radiative properties of metallic foil/metalized polymer foil and spacer on the basis of the inverse problem solution. The experiments were carried out for the sample of real MLI used for the BP-Colombo satellite (ESA). The recently developed theoretical model based on neglecting possible near-field effects in radiative heat transfer between closely spaced aluminum foils was used in theoretical predictions of heat transfer through the MLI.
Findings
A comparison of the computational results and the experimental data confirms that there are no significant near-field effects between the neighboring MLI layers. It means that there is no considerable contradiction between the far-field model of radiative transfer in MLI and the experimental estimates.
Originality/value
An identification procedure for mathematical model of the multilayer thermal insulation showed that a modified theoretical model developed recently can be used to estimate thermal properties of the insulation at conditions of space vacuum.
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Carlos Enrique Torres-Aguilar, Pedro Moreno-Bernal, Jesús Xamán, Ivett Zavala Guillen and Irving Osiris Hernández-López
This paper aims to present an evolutionary algorithm (EA) to accelerate the convergence for the radiative transfer equation (RTE) numerical solution using high-order and…
Abstract
Purpose
This paper aims to present an evolutionary algorithm (EA) to accelerate the convergence for the radiative transfer equation (RTE) numerical solution using high-order and high-resolution schemes by the relaxation coefficients optimization.
Design methodology/approach
The objective function minimizes the residual value difference between iterations in each control volume until its difference is lower than the convergence criterion. The EA approach is evaluated in two configurations, a two-dimensional cavity with scattering media and absorbing media.
Findings
Experimental results show the capacity to obtain the numerical solution for both cases on all interpolation schemes tested by the EA approach. The EA approach reduces CPU time for the RTE numerical solution using SUPERBEE, SWEBY and MUSCL schemes until 97% and 135% in scattering and absorbing media cases, respectively. The relaxation coefficients optimized every two numerical solution iterations achieve a significant reduction of the CPU time compared to the deferred correction procedure with fixed relaxation coefficients.
Originality/value
The proposed EA approach for the RTE numerical solution effectively reduces the CPU time compared to the DC procedure with fixed relaxation coefficients.
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Carlos Enrique Torres-Aguilar, Jesús Xamán, Pedro Moreno-Bernal, Iván Hernández-Pérez, Ivett Zavala-Guillén and Irving Osiris Hernández-López
The purpose of this study is to propose a novel relaxation modified factor to accelerate the numerical solution of the radiative transfer equation (RTE) with several…
Abstract
Purpose
The purpose of this study is to propose a novel relaxation modified factor to accelerate the numerical solution of the radiative transfer equation (RTE) with several high-resolution total variation diminishing schemes. The methodology proposed is denoted as the X-factor method.
Design/methodology/approach
The X-factor method was compared with the technique deferred-correction (DC) for the calculations of a two-dimensional cavity with absorting-emiting-scatteting gray media using the discrete ordinates method. Four parameters were considered to evaluate: the absorption coefficient, the emissivity of boundary surface, the scattering albedo and under-relaxation factor.
Findings
The results showed the central processing unit (CPU) time of X-factor method was lower than DC. The reductions of CPU time with the X-factor method were observed from 0.6 to 75.4%.
Originality/value
The superiority of the X-factor method over DC was showed with the reduction of CPU time of the numerical solution of RTE for evaluated cases.
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Ajay Kumar Chhabra and Prabal Talukdar
This paper aims to develop a numerical model to investigate coupled conduction radiation heat transfer in a multilayer semi-transparent polymeric foam.
Abstract
Purpose
This paper aims to develop a numerical model to investigate coupled conduction radiation heat transfer in a multilayer semi-transparent polymeric foam.
Design/methodology/approach
The model uses a multi-phase approach in which the radiative transfer is determined by solving the radiative transfer equation explicitly in the whole medium incorporating an interface condition valid in the geometric optics rgime. This is executed by using a combination of ray splitting and a discrete curved ray tracing technique. Both partial photon reflection and total internal reflection at the interface are considered in the present investigation.
Findings
The directional distribution of intensity within the whole medium can be determined, which is used to obtain the detailed temperature profile inside the domain. The performance of the proposed methodology has been tested by simulating the modelled foam at ambient conditions. The results obtained from the simulations are in good agreement with the published results and shows that there is a global non-linearity in the temperature profile in problems where conduction to radiation parameter is small.
Originality/value
Specular nature of radiative transfer at the interface is accounted for in the present analysis. Instead of working with direction integrated quantities (as in the case of P1 approximation), each bundle of rays is treated separately within the whole medium. This model serves as a starting point for a detailed spatially three dimensional study of heat transfer in foams and the mathematical nature of the formulation is such that it may result in an implementation to three-dimensions.
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Nesrine Sassi and Salma Damak-Ayadi
The purpose of this study is to examine the indirect relationship between the mandatory adoption of International Financial Reporting Standards for small and medium-sized…
Abstract
Purpose
The purpose of this study is to examine the indirect relationship between the mandatory adoption of International Financial Reporting Standards for small and medium-sized enterprises (IFRS for SMEs) and the corporate governance index (CGI) by checking the mediating effect of the quality of financial statements (QFS) on this relationship.
Design/methodology/approach
The main objective of the IFRS for SMEs standard is to meet the specific needs of SMEs in transition and developing economies. Here, the authors used the structural equation method to investigate SMEs in countries that mandate the application of IFRS for SMEs for the years 2010 (pre-adoption) and 2016 (post-adoption). The final sample covered two emerging countries: the Dominican Republic and El Salvador.
Findings
The results show a positive association between the adoption of IFRS for SMEs, CGI and QFS. Furthermore, the findings confirm that the relationship between IFRS for SMEs adoption and CGI is under the control of the QFS.
Originality/value
This study provides standard setters and managers of SMEs with an overview of the importance of QFS on the significance of this relationship in emerging countries. The study contributes to the literature by examining the indirect relationship between IFRS for SMEs and CGI and building a CGI that integrates a set of governance practices linked to SMEs.
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Olfa Ben Salah and Anis Ben Amar
The purpose of this paper is to focus on the impact of corporate social responsibility (CSR) on dividend policy in the French context. In addition, the authors seek to determine…
Abstract
Purpose
The purpose of this paper is to focus on the impact of corporate social responsibility (CSR) on dividend policy in the French context. In addition, the authors seek to determine if the individual components of CSR influence dividend policy.
Design/methodology/approach
This study uses panel data methodology for a sample of French non-financial firms between 2008 and 2018. Generalized least squares method is used to estimate the models.
Findings
Using panel data methodology for a sample of 825 observations for the period 2008–2018, this study finds a positive impact of CSR practices on dividend policy. The authors also find that individual components of CSR positively influence dividend policy. To check the robustness of the results, this study further runs a sensitivity tests, including an alternative measure of dividend policy, all of which confirm the findings.
Practical implications
This study has examined the impact of CSR on dividend policy in France and may have implications for regulatory, investors, analysts and academics. First, the involvement in CSR best practices encourages companies to pay more dividends to investors. Therefore, investors are more motivated to invest in socially responsible firms than socially irresponsible firms. Second, given the association of CSR with the quality of accounting information and financial markets, regulators should step up recommendations relating to the different societal dimensions of CSR.
Originality/value
While little previous work has focused on the causal link between CSR and dividend policy, this research is the first, to the authors’ knowledge, to have looked at the impact of CSR on dividend policy in France.