Search results

1 – 10 of 21
Article
Publication date: 7 November 2016

Abdelkader Frendi and Michael R. Brown

The purpose of this paper is to carry out an extensive numerical study in order to understand the flow structures and the resulting noise generated by a supersonic impinging jet…

Abstract

Purpose

The purpose of this paper is to carry out an extensive numerical study in order to understand the flow structures and the resulting noise generated by a supersonic impinging jet on a flat plate. One of the parameters varied in this study is the distance between the jet exit plane and the flat plate.

Design/methodology/approach

Because of the unsteady nature of the problem a time-dependent computation is carried out using the detached eddy simulation turbulence model. The OVERFLOW 2 CFD code was used with a highly resolved grid and small time steps.

Findings

The authors found that as the separation distance increases, the dominant frequencies in the noise spectrum decrease. In addition, the relative strength of the various frequencies to each other changes with changing distance, indicating the changing modes of the jet. The CFD results indicate a strong interaction between the acoustic waves emanating from the impingement plate and the jet plume. This feedback mechanism is responsible for destabilizing the jet shear layer leading to the jet changing modes. The computed near field spectra, convection velocities of the jet vortical structures and mean jet centerline velocity profile are in good agreement with experimental measurements. The results also show very high sound pressure levels all over the impingement plate but especially near the impingement point. These levels, if sustained, are detrimental to both human operators as well as the surrounding structures.

Research limitations/implications

Given the large-scale nature of the computations carried out, it is very costly to run the computations long enough to collect a good, statistically steady time sample to achieve a low frequency bandwidth resolution. Such a long time sample could actually improve the results in terms of frequency resolution and obtained an even better agreement with experiments. Off course there is always the issue of grid resolution as well, but given the good agreement with experiments that the authors obtained, the authors are confident in their results.

Practical implications

The practical implications of the results the authors obtained are significant in that, the authors now know that hybrid RANS-large eddy simulation methods can be used for this complex, unsteady engineering problems. In addition, the results also show the high noise level both on the impingement surface and in the surroundings of the jet. This could have a negative impact on the structural integrity of the flat surface.

Social implications

Noisy environments are never desirable anywhere especially in places where human operations take place. Therefore, given the high noise levels obtained in the simulations and confirmed by experiments, any human presence around the jet will be harmful to hearing and precautions need to be taken.

Originality/value

This is a physics-based study; i.e. understanding the physical phenomena involved in supersonic jet impingement. Of particular interest is the interaction of the jet shear layer with the acoustic waves emanating from the impingement area. This feedback loop is found to be responsible for intensifying the instability of the jet shear layer.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 9 July 2024

Ahmed Aboelfotoh, Ahmed Mohamed Zamel, Ahmad A. Abu-Musa, Frendy, Sara H. Sabry and Hosam Moubarak

This study aims to examine the ability of big data analytics (BDA) to investigate financial reporting quality (FRQ), identify the knowledge base and conceptual structure of this…

Abstract

Purpose

This study aims to examine the ability of big data analytics (BDA) to investigate financial reporting quality (FRQ), identify the knowledge base and conceptual structure of this research field and explore BDA techniques used over time.

Design/methodology/approach

This study uses a comprehensive bibliometric analysis approach (performance analysis and science mapping) using software packages, including Biblioshiny and VOSviewer. Multiple analyses are conducted, including authors, sources, keywords, co-citations, thematic evolution and trend topic analysis.

Findings

This study reveals that the intellectual structure of using BDA in investigating FRQ encompasses three clusters. These clusters include applying data mining to detect financial reporting fraud (FRF), using machine learning (ML) to examine FRQ and detecting earnings management as a measure of FRQ. Additionally, the results demonstrate that ML and DM algorithms are the most effective techniques for investigating FRQ by providing various prediction and detection models of FRF and EM. Moreover, BDA offers text mining techniques to detect managerial fraud in narrative reports. The findings indicate that artificial intelligence, deep learning and ML are currently trending methods and are expected to continue in the coming years.

Originality/value

To the best of the authors’ knowledge, this study is the first to provide a comprehensive analysis of the current state of the use of BDA in investigating FRQ.

Details

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

Keywords

Article
Publication date: 18 January 2024

Muhammad Mohsin Hakeem, Hoe Chin Goi and Frendy

This study aims to examine the participants’ [junior high school students and Master of business administration (MBA) consultants] perceptions and utilizations of the…

Abstract

Purpose

This study aims to examine the participants’ [junior high school students and Master of business administration (MBA) consultants] perceptions and utilizations of the multidimensional place-based resources within the context of Education for Sustainable Development (ESD), specifically focusing on its alignment with the sustainable development goals (SDGs) for quality education. While place-based resources have demonstrated the potential for fostering innovative thinking and collaborative efforts, a gap exists in understanding how these resources can be effectively integrated to bolster learning and sustainable outcomes.

Design/methodology/approach

The authors adopted a single-case research methodology and conducted an in-depth exploration of the integration of place-based resources within the context of ESD using the 2021 Forest Community Outreach (FCO) Project in Ena City, Japan. Questionnaires, daily journals and consultation reports were used for data collection. This study used the coding and qualitative content analysis process to understand the significance of the five dimensions of place-based resources in fostering effective ESD practices.

Findings

The findings show the gap between interest in ESD and utilization of place-based resources as reflected in the perceptions and interests of junior high school participants. MBA consultants acknowledged the relevance of leveraging the five dimensions of place-based resources in the context of ESD. This research enriches the understanding of recognizing and harnessing different resources within the settings, emphasizing the significance of a multidimensional place-based resources approach to effectively incorporate these resources into ESD, thereby fostering learning and practical sustainability outcomes.

Originality/value

This study conducts a novel analysis of diverse dimensions within the realm of place-based resources and their profound influence on the learning experiences and creativity of participants engaged in ESD. The study lays the groundwork for the validation of place-based resource dimensions through collaborative efforts involving stakeholders within the region.

Details

International Journal of Sustainability in Higher Education, vol. 25 no. 5
Type: Research Article
ISSN: 1467-6370

Keywords

Article
Publication date: 11 September 2017

Frendy and HU Dan Semba

The Accounting Standards Board of Japan (ASBJ) proposed a new set of endorsed International Financial Reporting Standards in June 2015. ASBJ claims that non-recycling of other…

Abstract

Purpose

The Accounting Standards Board of Japan (ASBJ) proposed a new set of endorsed International Financial Reporting Standards in June 2015. ASBJ claims that non-recycling of other comprehensive income (OCI) items decreases the information usefulness of earnings in a proposed comprehensive income standard. There has been no existing empirical evidence which supports the ASBJ’s statement and the purpose of the study is to test whether OCI recycling improves information usefulness of net income from six perspectives: relative and incremental value relevance, persistence, variability, operating cash flow and net income predictive power.

Design/methodology/approach

This paper is an empirical work using a listed Japanese firms sample of 5,385 firm-years from fiscal year 2012-2014.

Findings

The results challenge the ASBJ’s claim that recycling improves the general information usefulness characteristics of net income. The empirical results show that OCI recycling improves net income’s relative value relevance characteristic of financial firms. However, recycling information by itself does not improve the incremental value relevance, and the predictive power of operating cash flow and net income. The authors also find that the inclusion of recycling decreases the persistence and increases the variability of net income.

Research limitations/implications

This paper has two research limitations. First, this study is constrained to analyze a limited OCI recycling data that is recently disclosed by listed Japanese firms. Second, the results of this study have limited external validity to capital markets with OCI reclassification standards that deviate from Japanese GAAP.

Originality/value

This study provides initial empirical evidence that examines information usefulness of OCI recycling in Japan. The findings of this study are relevant for accounting standards setters aiming to increase the information usefulness of earnings for capital market investors.

Details

Asian Review of Accounting, vol. 25 no. 3
Type: Research Article
ISSN: 1321-7348

Keywords

Article
Publication date: 3 January 2017

Seyi F. Olatoyinbo, Sarma L. Rani and Abdelkader Frendi

The purpose of this study is to investigate the accuracy and applicability of the Flowfield Dependent Variation (FDV) method for large-eddy simulations (LES) of decaying isotropic…

Abstract

Purpose

The purpose of this study is to investigate the accuracy and applicability of the Flowfield Dependent Variation (FDV) method for large-eddy simulations (LES) of decaying isotropic turbulence.

Design/methodology/approach

In an earlier paper, the FDV method was successfully demonstrated for simulations of laminar flows with speeds varying from low subsonic to high supersonic Mach numbers. In the current study, the FDV method, implemented in a finite element framework, is used to perform LESs of decaying isotropic turbulence. The FDV method is fundamentally derived from the Lax–Wendroff Scheme (LWS) by replacing the explicit time derivatives in LWS with a weighted combination of explicit and implicit time derivatives. The increased implicitness and the inherent numerical dissipation of FDV contribute to the scheme’s numerical stability and monotonicity. Understanding the role of numerical dissipation that is inherent to the FDV method is essential for the maturation of FDV into a robust scheme for LES of turbulent flows. Accordingly, three types of LES of decaying isotropic turbulence were performed. The first two types of LES utilized explicit subgrid scale (SGS) models, namely, the constant-coefficient Smagorinsky and dynamic Smagorinsky models. In the third, no explicit SGS model was employed; instead, the numerical dissipation inherent to FDV was used to emulate the role played by explicit SGS models. Such an approach is commonly known as Implicit LES (ILES). A new formulation was also developed for quantifying the FDV numerical viscosity that principally arises from the convective terms of the filtered Navier–Stokes equations.

Findings

The temporal variation of the turbulent kinetic energy and enstrophy and the energy spectra are presented and analyzed. At all grid resolutions, the temporal profiles of kinetic energy showed good agreement with t(−1.43) theoretical scaling in the fully developed turbulent flow regime, where t represents time. The energy spectra also showed reasonable agreement with the Kolmogorov’s k(−5/3) power law in the inertial subrange, with the spectra moving closer to the Kolmogorov scaling at higher-grid resolutions. The intrinsic numerical viscosity and the dissipation rate of the FDV scheme are quantified, both in physical and spectral spaces, and compared with those of the two SGS LES runs. Furthermore, at a finite number of flow realizations, the numerical viscosities of FDV and of the Streamline Upwind/Petrov–Galerkin (SUPG) finite element method are compared. In the initial stages of turbulence development, all three LES cases have similar viscosities. But, once the turbulence is fully developed, implicit LES is less dissipative compared to the two SGS LES runs. It was also observed that the SUPG method is significantly more dissipative than the three LES approaches.

Research limitations/implications

Just as any computational method, the limitations are based on the available computational resources.

Practical implications

Solving problems involving turbulent flows is by far the biggest challenge facing engineers and scientists in the twenty-first century, this is the road that the authors have embarked upon in this paper and the road ahead of is very long.

Social implications

Understanding turbulence is a very lofty goal and a challenging one as well; however, if the authors succeed, the rewards are limitless.

Originality/value

The derivation of an explicit expression for the numerical viscosity tensor of FDV is an important contribution of this study, and is a crucial step forward in elucidating the fundamental properties of the FDV method. The comparison of viscosities for the three LES cases and the SUPG method has important implications for the application of ILES approach for turbulent flow simulations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 3 February 2023

Frendy and Fumiko Takeda

Partners are responsible for allocating audit tasks and facilitating knowledge sharing among team members. This study considers changes in the composition of partners to proxy for…

Abstract

Purpose

Partners are responsible for allocating audit tasks and facilitating knowledge sharing among team members. This study considers changes in the composition of partners to proxy for the continuity of the audit team. This study examines the effect of audit team continuity on audit outcomes (audit quality and report lags), pricing and its determinant (lead partner experience), which have not been thoroughly examined in previous studies.

Design/methodology/approach

This study employs string similarity metrics to measure audit team continuity. The study employs multivariate panel data regression empirical models to estimate a sample of 26,007 firm-years of listed Japanese companies from 2008 to 2019.

Findings

The study reveals that audit team continuity is negatively associated with audit fees, regardless of the auditor’s size. This finding contributes to the existing literature by showing that audit team continuity represents one of the determinant factors of audit fee. For clients of large audit firms, companies with higher (lower) audit team continuity issue audit reports in less (more) time. The experience of lead partners is a strong predictor of audit team continuity, irrespective of audit firm size. Audit quality is not associated with audit team continuity for either large or small audit firms.

Originality/value

This study proposes and examines audit team continuity measures that employ string similarity metrics to quantify changes in the composition of partners in consecutive audit engagements. Audit team continuity expands upon the tenure of individual audit partners, which is commonly used in prior literature as a measure of client–partner relationships.

Details

Journal of Accounting Literature, vol. 45 no. 2
Type: Research Article
ISSN: 0737-4607

Keywords

Article
Publication date: 18 July 2022

Frendy Frendy, Hoe Chin Goi, Muhammad Mohsin Hakeem and Kuok Kei Law

This paper aims to offer an empirical application of the concept of learning organization (LO) 2.0.

Abstract

Purpose

This paper aims to offer an empirical application of the concept of learning organization (LO) 2.0.

Design/methodology/approach

Based on fieldwork study, a case of Ricoh Ena Forest Project is presented to illustrate the contextualized and multi-stakeholder perspective of LO 2.0 in running an environmental sustainability project.

Findings

The case demonstrated the value of incorporating multiple stakeholders to develop a multi-party learning entity for sustainability pursuit. The findings also highlighted the importance of forfeiting managerial dominance and the creation of a shared commitment in implementing the concept of LO 2.0.

Originality/value

The study adds empirical evidence to the literature on how LO 2.0 can be implemented and provides guidance on tackling some of the potential challenges.

Details

The Learning Organization, vol. 29 no. 5
Type: Research Article
ISSN: 0969-6474

Keywords

Article
Publication date: 1 August 2016

Man Zhang and Abdelkader Frendi

The tubercles at the leading edge of Humpback Whale flippers have been shown to increase aerodynamic efficiency. The purpose of this paper is to compute the flow structures and…

Abstract

Purpose

The tubercles at the leading edge of Humpback Whale flippers have been shown to increase aerodynamic efficiency. The purpose of this paper is to compute the flow structures and noise signature of a NACA0012 airfoil with and without leading edge waviness, and located in the wake of a cylinder using the hybrid RANS-LES method.

Design/methodology/approach

The mean flow Mach number is 0.2 and the angle of attack used is 2°. After benchmarking the method using existing experimental results, unsteady computations were then carried-out on both airfoil geometries and for a 2° angle of attack.

Findings

Results from these computations confirmed the aerodynamic benefits of the leading edge waviness. Moreover, the wavy leading edge airfoil was found to be at least 4 dB quieter than its non-wavy counterpart. In-depth analysis of the computational results revealed that the wavy leading edge airfoil breaks up the large coherent structures which are then convected at higher speeds down the trough region of the waviness in agreement with previous experimental observations. This result is supported by both the two-point and space-time correlations of the wall pressure.

Research limitations/implications

The limitations of the current findings reside in the fact that both the Reynolds number and the flow Mach number are low, therefore not applicable to aircrafts. In order to extend the study to practical aircrafts one needs huge grids and large computational resources.

Practical implications

The results obtained here could have a huge implications on the design of future aircrafts and spacecrafts. More specifically, the biggest benefit from such redesign is the reduction of acoustic signature as well as increased efficiency in fuel consumption.

Social implications

Reducing acoustic signature from aircrafts has been a major research thrust for NASA and Federal Aviation Administration. The social impact of such reduction would be improved quality of life in airport communities. For military aircrafts, this could results in reduced detectability and hence saving lives.

Originality/value

Humpback Whales have been studied by various researchers to understand the effects of leading edge “tubercles” on flow structures. What is new in this study is the numerical confirmation of the effects of the tubercles on the flow structures and the resulting noise radiations. It is shown through the use of two-point correlations and space-time correlations that the flow structures in the trough area are indeed vortex tubes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 6 June 2016

Bassem R Girgis, Sarma L Rani and Abdelkader Frendi

The purpose of this paper is to investigate the computational features of the Flowfield Dependent Variation (FDV) method, a numerical scheme built to simulate flows characterized…

Abstract

Purpose

The purpose of this paper is to investigate the computational features of the Flowfield Dependent Variation (FDV) method, a numerical scheme built to simulate flows characterized by multiple speeds, multiple physical phenomena, and by large variations in flow variables.

Design/methodology/approach

Fundamentally, the FDV method may be regarded as a variant of the Lax-Wendroff Scheme (LWS) that is obtained by replacing the explicit time derivatives in LWS by a weighted combination of explicit and implicit time derivatives. The weighting factors – referred to as FDV parameters – may be broadly classified as convective and diffusive parameters which, for example, are determined using flow quantities such as the Mach number and Reynolds number, respectively. Hence, the reference to these parameters and the method as “flow field dependent.” A von Neumann Fourier analysis demonstrates that the increased implicitness makes FDV both more stable and less dispersive compared to LWS, a feature crucial to capturing shocks and other phenomena characterized by high gradients in variables. In the current study, the FDV scheme is implemented in a Taylor-Galerkin-based finite element method framework that supports arbitrarily high order, unstructured isoparametric elements in one-, two- and three-dimensional geometries.

Findings

At first, the spatial accuracy of the implemented FDV scheme is established using the Method of Manufactured Solutions, wherein the results show that the order of accuracy of the scheme is nearly equal to the order of the shape function polynomial plus one. The dispersion and dissipation errors of FDV, when applied to the compressible Navier-Stokes and energy equations, are investigated using a 2-D, small-amplitude acoustic pulse propagating in a quiescent medium. It is shown that FDV with third-order shape functions accurately captures both the amplitude and phase of the acoustic pulse. The method is then applied to cases ranging from low-Mach number subsonic flows (Mach number M=0.05) to high-Mach number supersonic flows (M=4) with shock-boundary layer interactions. For all cases, fair to good agreement is observed between the current results and those in the literature.

Originality/value

The spatial order of accuracy of the FDV method, its stability and dispersive properties, as well as its applicability to low- and high-Mach number flows are established.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 16 February 2022

Wei Qian, Ping Zhu and Carol Tilt

Recent research has drawn attention to the tension between the Central and local governments in China regarding their roles in environmental protection. This paper aims to explore…

Abstract

Purpose

Recent research has drawn attention to the tension between the Central and local governments in China regarding their roles in environmental protection. This paper aims to explore this tension and examine the extent to which local/provincial government’s environmental oversight has influenced the quality of corporate environmental disclosure in China.

Design/methodology/approach

A sample of 198 listed companies in heavily polluting industries were selected to examine the relationship between their environmental disclosure quality and the respective local government’s environmental oversight level.

Findings

The results provide evidence that local/provincial government’s environmental oversight significantly influences environmental disclosure in China. Despite the coercive pressure from the powerful Central government on corporate environmental disclosure, local/provincial governments are able to buffer the pressure and adjust the intensity of their environmental oversight on companies during the implementation of central policies to retain local economic and political interests. This may partially explain the persistent issue of low environmental disclosure quality in China.

Research limitations/implications

This study enriches our understanding of the significant role of local governments in China in enhancing or sometimes discounting the regulatory enforcement of the Central government on corporate environmental disclosure, pointing to the need for concerted efforts by both local and Central governments to advance environmental disclosure development.

Originality/value

Research on environmental disclosure in developed countries has been well established in the literature. However, such research in developing nations is still limited, especially in China, the world largest developing country. The existing literature on environmental disclosure in China links it with either market demands, or regulatory enforcement from the Central government. The importance of local/provincial governments and their environmental oversight has long been ignored, which motivates this research.

Details

Pacific Accounting Review, vol. 34 no. 2
Type: Research Article
ISSN: 0114-0582

Keywords

1 – 10 of 21