Mohamed Rady, Eric Arquis, Dominique Gobin and Benoît Goyeau
This paper aims to tackle the problem of thermo‐solutal convection and macrosegregation during ingot solidification of metal alloys. Complex flow structures associated with the…
Abstract
Purpose
This paper aims to tackle the problem of thermo‐solutal convection and macrosegregation during ingot solidification of metal alloys. Complex flow structures associated with the development of channels segregate and sharp gradients in the solutal field call for the implementation of accurate methods for numerical modeling of alloy solidification. In particular, the solute transport equation is convection dominated and requires special non‐oscillarity type high‐order schemes to handle the regions of channels segregates.
Design/methodology/approach
In the present study, a time‐splitting approach has been adopted to separately handle solute advection and diffusion. This splitting technique allows the application of accurate total variation dimensioning (TVD) schemes for solution of solute advection. Applications of second‐order Lax‐Wendroff TVD SUPERBEE and fifth‐order weighted essentially non‐oscillatory (WENO) schemes are described in the present article. Classical numerical solution of solute transport using hybrid and central‐difference schemes are also employed for the purpose of comparisons. Numerical simulations for solidification of Pb‐18%Sn in a two‐dimensional rectangular cavity have been carried out using different numerical schemes.
Findings
Numerical results show the difficulty of obtaining grid‐independent solutions with respect to local details in the region of channels. Grid convergence patterns and numerical uncertainty are found to be dependent on the applied scheme. In general, the first‐order hybrid scheme is diffusive and under predicts the formation of channels. The second‐order central‐difference scheme brings about oscillations with possible non‐physical extremes of solute composition in the region of channel segregates due to sharp gradients in the solutal field. The results obtained using TVD and WENO schemes contain no oscillations and show an excellent capture of channels formation and resolution of the interface between solute‐rich and depleted bands. Different stages of channels formation are followed by analyzing thermo‐solutal convection and macrosegregation at different times during solidification.
Research limitations/implications
Accurate prediction of local variation in the solutal and flow fields in the channels regions requires grid refinement up to scales in the order of microscopic dendrite arm spacing. This imposes limitations in terms of large computational time and applicability of available macroscopic models based on classical volume‐averaging techniques.
Practical implications
The present study is very useful for numerical simulation of macrosegregation during ingot casting of metal alloys.
Originality/value
The paper provides the methodology and application of TVD schemes to predict channel segregates during columnar solidification of metal alloys. It also demonstrates the limitations of classical schemes for simulation of alloy solidification.
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Mohamed Elheddad, Abdelrahman J.K. Alfar, Radi Haloub, Neetu Sharma and Patrick Gomes
The purpose of this study is to identify the effects of MNCs measured by the foreign direct investment (FDI) inflows on the promotion of renewable energy consumption and…
Abstract
Purpose
The purpose of this study is to identify the effects of MNCs measured by the foreign direct investment (FDI) inflows on the promotion of renewable energy consumption and non-renewable energy in Bangladesh. It is an emergency issue these days and makes some policy suggestions.
Design/methodology/approach
Based on the literature review, the study sets a time series models to empirically test FDI degrades the environmental quality in Bangladesh, using the parametric (GMM, IV estimations) and non-parametric approaches (quantile regression).
Findings
The main findings drawn from the empirical analysis are as follows. First, the FDI inflows lead to more CO2 emissions in the Bangladeshi economy. In other words, the MNCs promote the usages of non-renewable energy which causes an increase in pollution. Second, the FDI inwards discourage renewable energy consumption and in terms of magnitude, the negative impacts of FDI on renewable energy are higher than the positive effect of FDI on CO2 emissions. This makes the situation worse.
Research limitations/implications
This study is limited to Bangladesh and explores the total impact of FDI on the environment. For further investigation, it would be better to do a detailed investigation on the FDI-renewable and nonrenewable energy relationship. For instance, one could test which type of FDI promotes green energy consumption and which one is dirtier. So, the sectorial FDI effects on pollution.
Originality/value
Most past studies parametric techniques and did not compare the effects of FDI on renewable and non-renewable energy consumption, Unlike the previous empirical studies, this paper uses GMM and IV estimations for the parametric approach and quantile regression (QR) as a robustness check. Also, it is the first study that approves the crowding-out effect of non-renewable using the FDI channel.
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Brahim Ladghem Chikouche, Kamel Boughrara and Rachid Ibtiouen
This paper aims to the improvement of permanent magnet shape in the popular permanent magnet synchronous machine (PMSM) is proposed in this paper in view to mitigate cogging…
Abstract
Purpose
This paper aims to the improvement of permanent magnet shape in the popular permanent magnet synchronous machine (PMSM) is proposed in this paper in view to mitigate cogging torque magnitude and torque ripple.
Design/methodology/approach
A two-dimensional exact analytical approach of magnetic field distribution is established for the PMSM considering magnet shape and slot opening. The optimal magnet shape is constituted of small number of layers stacked radially. The thickness of each magnet layer is considered equal to about one mm or more; however, a parametric study was performed to determine pole pitch ratio value. The finite element method is used to validate the analytical results.
Findings
Cogging torque peaks and torque ripples can be mitigated significantly more than 90 per cent compared to results issued from machine having classical magnet shape. Raising the number of magnet layers can give better results. The results of this paper are compared also with those issued from the machine having sinusoidal magnet shape and give a good solution.
Originality/value
A new technique for cogging torque and torque ripple mitigation is proposed in this paper by changing permanent magnet shape. The proposed final magnet shape is constituted of a set of stacked and well-dimensioned layers relative to the opening angle.
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Ahmed Helmy Mohamed Gomaa Mohamed
The current study aims to analyze the role of International Federation of Accountants (IFAC) in sustainability issues and its impact on the attitude of practitioners (auditors) in…
Abstract
The current study aims to analyze the role of International Federation of Accountants (IFAC) in sustainability issues and its impact on the attitude of practitioners (auditors) in industrial companies. The current study relies on the analytical method, one of the tools of the inductive approach, by examining the literature of researchers, international and local organizations, publications, series, alerts, and topics dealt with by the IFAC, as well as reviewing studies, theoretical and applied research, periodicals, books, and statistics. And specialized publications for this subject, which is related to other sciences – such as – environmental science, economic, and political sciences. The study reached many results, the most important of which are: (1) The first half of the current decade has seen high interest from the IFAC, has led to the issuance of International Auditing and Assurance Standards Board (IAASB) international standard on assurance engagements 3410, (GHG) Statements. (2) Sustainability has become important to a growing number of enterprises, and may have a significant influence, in certain cases, the financial statements, also became the sustainability of the topics under increasing attention from users of financial statements. Thus, the financial statements will need a practitioner to take into consideration sustainability issues and a private greenhouse gas when auditing the financial statements. This study is distinguished by analyzing the role of the IFAC and the IAASB for the period from 1998 to 2023 regarding sustainability issues.
In the present work, under severe conditions of an inert atmosphere and high temperature, epoxidized natural rubber (ENR) with 25 per cent epoxidation level reacts with different…
Abstract
Purpose
In the present work, under severe conditions of an inert atmosphere and high temperature, epoxidized natural rubber (ENR) with 25 per cent epoxidation level reacts with different aliphatic amine compounds such as ethyl amine (EA), propyl amine (PA) and butyl amine (BA) to prepare ENR/EA, ENR/PA, ENR/BA compounds as, respectively. The produced compounds were characterized by Fourier transform infrared spectroscopy and oxirane oxygen content determination. Different concentrations of the produced compounds were added to epoxy and urethane acrylate coating formulations to evaluate them as corrosion inhibitors for mild steel under UV irradiation. Corrosion resistance tests and weight loss measurements of the coated steel panels were made. It was found that coating formulations containing the prepared ENR/EA compound could protect metal surface from corrosion, and corrosion inhibitors efficiency of the prepared compounds were arranged as follows: ENR/EA > ENR/PA > ENR/BA. The optimum concentrations for all inhibitors which give the best inhibition efficiency for corrosion are 0.4-0.6 phr.
Design/methodology/approach
Corrosion scratch tests were carried out according to ASTM D 1,654-92 (2000). The weight loss of coated steel was measured according to ASTM D 2,688-94 (1999). The measurement of film hardness was carried out with a Wolff–Wilborn pencil hardness tester according to ASTM D 3,363 (2000).
Findings
It was found that coating formulations containing the prepared ENR/EA compound could protect metal surface from corrosion and corrosion inhibitors efficiency of the prepared compounds were arranged as follows: ENR/EA > ENR/PA > ENR/BA. The optimum concentrations for all inhibitors are 0.4-0.6 g/100g coating.
Originality/value
A highly efficient and economically corrosion inhibitors for mild steel were prepared from ENR and series of aliphatic amines.
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Mohamed Samy El-Deeb, Tariq H. Ismail and Alia Adel El Banna
This paper aims to examine the impact of environmental, social and governance (ESG) disclosure and firm value (FV), as well as, pinpoints the role of the audit quality (AQ) as a…
Abstract
Purpose
This paper aims to examine the impact of environmental, social and governance (ESG) disclosure and firm value (FV), as well as, pinpoints the role of the audit quality (AQ) as a moderating variable on such impact; where the authors hypothesize that AQ modulates the relationship between ESG disclosure and the FV.
Design/methodology/approach
Data of a sample of firms listed on the Egyptian Stock Exchange Market (EGX) were collected over the period of 2017–2021 and analyzed using the regression and 2SLS models.
Findings
The results suggested that: (1) the ESG has a significant positive impact on the FV in the EGX, and (2) AQ has a significant impact, as a moderating variable, on the relationship between ESG disclosure and FV.
Research limitations/implications
The findings would help the Egyptian market authorities in realizing the importance of integrating ESG information within the financial reports of the listed firms. The findings could also help in developing effective disclosure procedures to provide shareholders with useful information.
Originality/value
This paper contributes to the literature regarding the ESG disclosure components and the FV value by considering AQ in testing such relationship.
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Fairouz Badaj and Bouchra Radi
The main purpose of the study is to examine the willingness of Moroccan small- and medium-sized enterprises (SMEs) to adopt profit and loss sharing (PLS) method of finance and the…
Abstract
Purpose
The main purpose of the study is to examine the willingness of Moroccan small- and medium-sized enterprises (SMEs) to adopt profit and loss sharing (PLS) method of finance and the factors that may influence their decision.
Design/methodology/approach
The research model is based on the decomposed theory of planned behaviour (DTPB). A total of 340 questionnaires were randomly distributed to SMEs’ owner-managers, out of which 177 were collected and only 153 were valid for analysis. Factor analysis and partial least squares regression were subsequently applied.
Findings
The results showed that cost, loss of control, constrained access to conventional debt, financial suitability, stage of development as well as religious beliefs have a significant impact on the SMEs’ attitude towards PLS modes. Likewise, normative belief was also found to have a significant influence on subjective norm, by particular reference to the family, financial external consultants and internal managers, as the main referent groups. In addition, finally, attitude and perceived behavioural control were found to have a significant impact on the intention to adopt PLS financing by Moroccan SMEs.
Research limitations/implications
The sample is not representative; hence, the findings cannot be generalized to all Moroccan SMEs. Furthermore, the variables and dimensions used are not exhaustive. With regard to implications, the study confirms the applicability of the DTPB to SME financing questions. Moreover, this study provides great indications to the practitioners, investors, policy makers and regulators on the perception of the Moroccan entrepreneurs, which should be taken into consideration to establish the necessary strategies to attract them.
Originality/value
This paper verifies the applicability of the DTPB in another area, that is, adoption of PLS instruments and contributes to explain the entrepreneurs’ perceptions towards theses modes of financing.
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In this paper, two promising corrosion inhibitors based on natural and eco-friendly materials such as peanut fatty acids (PFA) were prepared and challenged with a common efficient…
Abstract
Purpose
In this paper, two promising corrosion inhibitors based on natural and eco-friendly materials such as peanut fatty acids (PFA) were prepared and challenged with a common efficient commercial inhibitor. Two amino derivatives based on aliphatic and aromatic compounds such as 2-amino-2-methyl-1-propanol (AMP) and 2-amino-2-phenyl-1-propanol (APP), respectively, were used and reacted with PFA under controlled conditions to produce the corrosion inhibitors. The prepared inhibitors, namely, PFA-AMP (inhІ) and PFA-APP (inhІІ), were confirmed and characterized by Fourier transfer infrared spectroscopy, acid value determination and viscosity measurements.
Design/methodology/approach
First, different coating formulations free from any inhibitors were prepared and irradiated under different doses of electron beam source to select the best dose. Several concentrations of synthesized anticorrosion materials were then added to coating formulations to estimate them as anticorrosion materials for mild steel panels. Then, all formulations were coated and polymerized at a dose of 10 kGy. The corrosion tests, weight loss and water uptake were studied for all films after immersion in 3.5% sodium chloride. Moreover, the chemical and physico-mechanical properties were determined for all films.
Findings
The results exhibited that the different concentrations of two inhibitors did not show any significant change on the different properties of all films, and the best concentration, which gives the better protection for steel panels, was to be 1.0 g for two inhibitors.
Originality/value
It was found that the protection efficiency of the inhІ is better and higher than that of the inhІІ and also of the commercial inhibitor with the following order: inhІ > commercial inhibitor > inhІІ.
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Adi Ainurzaman Jamaludin, Nila Keumala, Ati Rosemary Mohd Ariffin and Hazreena Hussein
Three residential colleges located in a university campus at the capital city of Kuala Lumpur and built in different decades were selected for landscape studies with respect to…
Abstract
Three residential colleges located in a university campus at the capital city of Kuala Lumpur and built in different decades were selected for landscape studies with respect to species and position of the trees, as well as the effects of the current landscapes as a shelter in reducing solar radiation on buildings, as a pre-assessment for the Low Carbon Cities Framework (LCCF) and assessment system. These landscape designs were carefully studied through on-site observation. The name and location of the matured plants were redrawn and visualised with standard normal photographs. The studies revealed that the old residential college landscape is dominated by tropical forest trees which are able to provide a significant shade to the buildings and offered a potential to achieve sustainable development due to a higher rate of carbon sequestration. While, palm and hybrid fruit plants were most extensively cultivated in the landscape of new residential colleges due to low maintenance and being fast growing.