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Article
Publication date: 1 January 2014

S. Jafari, M. Rahnama and E. Jahanshahi Javaran

– The present work aims to deal with simulation of turbulent duct flow using generalized lattice Boltzmann equation (GLBE) in which large eddy simulation was employed.

204

Abstract

Purpose

The present work aims to deal with simulation of turbulent duct flow using generalized lattice Boltzmann equation (GLBE) in which large eddy simulation was employed.

Design/methodology/approach

The sub-grid scale turbulence effects were simulated through a shear-improved Smagorinsky model (SISM) which is capable of predicting turbulent near wall region accurately without any wall function. Computations were done for fully developed turbulent square duct flow at Ret=300, based on duct width and average friction velocity.

Findings

Results obtained for turbulent duct flow reveal that the GLBE in conjunction with SISM is able to correctly predict the existence of secondary flows and the computed detailed structure of first- and second-order statistics of main and secondary motions. The methodology is validated by comparing with previously published data. It is concluded that such framework is capable of predicting accurate results for turbulent duct flow. In addition, the operations in the present method are local; it can be easily programmed for parallel machines.

Originality/value

The numerical method, including generalized lattice Boltzmann method with forcing term and implementation of SISM in GLBE, is used for the first time to simulate turbulent duct flow.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 27 November 2020

Mehdi Rahnama, Abolfazl Vahedi, Arta Mohammad-Alikhani and Noureddine Takorabet

On-time fault diagnosis in electrical machines is a critical issue, as it can prevent the development of fault and also reduce the repairing time and cost. In brushless…

184

Abstract

Purpose

On-time fault diagnosis in electrical machines is a critical issue, as it can prevent the development of fault and also reduce the repairing time and cost. In brushless synchronous generators, the significance of the fault diagnosis is even more because they are widely used to generate electrical power all around the world. Therefore, this study aims to propose a fault detection approach for the brushless synchronous generator. In this approach, a novel extension of Relief feature selection method is developed.

Design/methodology/approach

In this paper, by taking the advantages of the finite element method (FEM), a brushless synchronous machine is modeled to evaluate the machine performance under two conditions. These conditions include the normal condition of the machine and one diode open-circuit of the rotating rectifier. Therefore, the harmonic behavior of the terminal voltage of the machine is obtained under these situations. Then, the harmonic components are ranked by using the extension of Relief to extract the most appropriate components for fault detection. Therefore, a fault detection approach is proposed based on the ranked harmonic components and support vector machine classifier.

Findings

The proposed diagnosis approach is verified by using an experimental test. Results show that by this approach open-circuit fault on the diode rectifier can effectively be detected by the accuracy of 98.5% and by using five harmonic components of the terminal voltage [1].

Originality/value

In this paper, a novel feature selection method is proposed to select the most effective FFT components based on an extension of Relief method, and besides, FEM modeling of a brushless synchronous generator for normal and one diode open-circuit fault.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 39 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 7 November 2023

Hassan Rahnama Haratbar, Mehrzad Saeedikiya and Mohammad Hassan Seif

This study in Iran examined the role of internal and external psychological factors that affected green purchase intention. Moreover, it examined these variables' direct and…

620

Abstract

Purpose

This study in Iran examined the role of internal and external psychological factors that affected green purchase intention. Moreover, it examined these variables' direct and indirect effects and green purchase intention on green purchase behavior.

Design/methodology/approach

An extended version of the theory of planned behavior (TPB) was employed, based on which a theoretical model was designed to reach the authors’ aim. An online questionnaire was used to collect data. For data analysis, confirmatory factor analysis, structural equation modeling, the bootstrapping method and the Preschool Language Scale (PLS) product-indicator approach were conducted to test the proposed conceptual model.

Findings

Results show that self-identity, self-interest, self-efficacy and a growth mindset have a positive impact on green purchase intention. However, the study found no predictive effect from peer influence and warm glow. In addition, self-efficacy and green purchase intention significantly affect green purchase behavior. The study reveals that green purchase intention substantially mediates the relationship between self-interest, growth mindset, warm glow and green purchase behavior. Further, warm glow moderates the impact of peer influence, self-identity and self-efficacy on green purchase intention. This study emphasizes the critical role of dispositional factors on green purchase intention and behavior.

Originality/value

Few studies consider the effect of the individual self, a growth mindset, a warm glow and peer influence on green purchase intention simultaneously. In addition, the authors introduced a different version of the TPB model. Further, this research also conducted how these variables, directly and indirectly, affect green purchase behavior.

Details

Management of Environmental Quality: An International Journal, vol. 35 no. 3
Type: Research Article
ISSN: 1477-7835

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Article
Publication date: 8 February 2022

Hassan Rahnama and Peter T.L. Popkowski Leszczyc

Few marketing studies have studied consumer mindsets about sustainable products in developing countries. This paper examines the influence of fixed and growth mindsets on buying…

712

Abstract

Purpose

Few marketing studies have studied consumer mindsets about sustainable products in developing countries. This paper examines the influence of fixed and growth mindsets on buying sustainable foods in Iran.

Design/methodology/approach

To reach this goal, the authors designed a conceptual model and specified hypotheses. A non-probability survey of 622 people was conducted through a multistage cluster random sampling from two provinces in north Iran: Gilan and Mazandaran. Data were collected through a face-to-face questionnaire. A chi-square test, confirmatory factor analysis, structural equation modelling, the bootstrapping method and the PLS product-indicator approach were used for analyses.

Findings

Results show that fixed and growth mindsets have a positive impact on buying sustainable foods. In addition, these two mindsets have a significant effect on consumers' health concerns and warm glow. The study demonstrates that health concerns, environmental values and convenience orientation mediate the relationship between growth mindset and sustainable shopping. However, for a fixed mindset, environmental values are not a mediator. Further, peer influence significantly moderates the effect of both mindsets and motivational variables—environmental values, convenience orientation and warm glow—on purchasing sustainable foods. This study emphasises the critical role of peer influence and motivation factors, including health concern, convenience and warm glow, on purchasing sustainable foods.

Originality/value

This research introduces a new framework concerning consumer behaviour, in particular, consumer psychology towards buying sustainable foods.

Details

British Food Journal, vol. 124 no. 12
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 23 July 2024

Dereje Fedasa Hordofa

The purpose of this study is to empirically examine the impact of natural resource rents on income inequality in Ethiopia from 1981 to 2022 and investigate whether investments in…

44

Abstract

Purpose

The purpose of this study is to empirically examine the impact of natural resource rents on income inequality in Ethiopia from 1981 to 2022 and investigate whether investments in manufacturing moderate this relationship.

Design/methodology/approach

Dynamic autoregressive distributed lag simulation and Kernel-based regularized least squares (KRLS) models are used to analyses short- and long-run relationships, as well as the potential moderating role of manufacturing.

Findings

The bounds test indicates natural resource rents have a long-run positive effect on inequality but a short-run negative impact. The KRLS model finds manufacturing conditions for this linkage in the short run. In the long run, economic growth decreases inequality following an inverted Kuznets pattern, while government expenditures reduce disparities when directed at priority social services.

Research limitations/implications

The findings provide mixed support for theories while highlighting nuances not fully captured without local analyses. Strategic sectoral investments may help optimize outcomes from resource dependence.

Practical implications

The results imply Ethiopia should prudently govern resources, productively invest revenues and prioritize social spending to equitably manage industrialization and uphold stability.

Social implications

Reducing disparities through inclusive development aligned with empirical evidence could help Ethiopia sustain peace amid transformation and realize its goals of shared prosperity.

Originality/value

This study applies innovative econometrics to provide novel insights into Ethiopia's experience, resolving inconsistencies in the literature on relationships between key determinants and inequality.

Details

International Journal of Development Issues, vol. 24 no. 1
Type: Research Article
ISSN: 1446-8956

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Article
Publication date: 17 July 2019

Ali Ayyed Abdul-Kadhim, Fue-Sang Lien and Eugene Yee

This study aims to modify the standard probabilistic lattice Boltzmann methodology (LBM) cellular automata (CA) algorithm to enable a more realistic and accurate computation of…

171

Abstract

Purpose

This study aims to modify the standard probabilistic lattice Boltzmann methodology (LBM) cellular automata (CA) algorithm to enable a more realistic and accurate computation of the ensemble rather than individual particle trajectories that need to be updated from one time step to the next (allowing, as such, a fraction of the collection of particles in any lattice grid cell to be updated in a time step, rather than the entire collection of particles as in the standard LBM-CA algorithm leading to a better representation of the dynamic interaction between the particles and the background flow). Exploitation of the inherent parallelism of the modified LBM-CA algorithm to provide a computationally efficient scheme for computation of particle-laden flows on readily available commodity general-purpose graphics processing units (GPGPUs).

Design/methodology/approach

This paper presents a framework for the implementation of a LBM for the simulation of particle transport and deposition in complex flows on a GPGPU. Towards this objective, the authors have shown how to map the data structure of the LBM with a multiple-relaxation-time (MRT) collision operator and the Smagorinsky subgrid-scale turbulence model (for turbulent fluid flow simulations) coupled with a CA probabilistic method (for particle transport and deposition simulations) to a GPGPU to give a high-performance computing tool for the calculation of particle-laden flows.

Findings

A fluid-particle simulation using our LBM-MRT-CA algorithm run on a single GPGPU was 160 times as computationally efficient as the same algorithm run on a single CPU.

Research limitations/implications

The method is limited by the available computational resources (e.g. GPU memory size).

Originality/value

A new 3D LBM-MRT-CA model was developed to simulate the particle transport and deposition in complex laminar and turbulent flows with different hydrodynamic characteristics (e.g. vortex shedding, impingement, free shear layer, turbulent boundary layer). The solid particle information is encapsulated locally at the lattice grid nodes, allowing for straightforward mapping of the datastructure onto a GPGPU enabling a massive parallel execution of the LBM-MRT-CA algorithm. The new particle transport algorithm was based on the local (bulk) particle density and velocity and provides more realistic results for the particle transport and deposition than the standard LBM-CA algorithm.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 7
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 9 January 2023

Luis Zárate, Marcos W. Rodrigues, Sérgio Mariano Dias, Cristiane Nobre and Mark Song

The scientific community shares a heritage of knowledge generated by several different fields of research. Identifying how scientific interest evolves is relevant for recording…

199

Abstract

Purpose

The scientific community shares a heritage of knowledge generated by several different fields of research. Identifying how scientific interest evolves is relevant for recording and understanding research trends and society’s demands.

Design/methodology/approach

This article presents SciBR-M, a novel method to identify scientific interest evolution from bibliographic material based on Formal Concept Analysis. The SciBR-M aims to describe the thematic evolution surrounding a field of research. The method begins by hierarchically organising sub-domains within the field of study to identify the themes that are more relevant. After this organisation, we apply a temporal analysis that extracts implication rules with minimal premises and a single conclusion, which are helpful to observe the evolution of scientific interest in a specific field of study. To analyse the results, we consider support, confidence, and lift metrics to evaluate the extracted implications.

Findings

The authors applied the SciBR-M method for the Educational Data Mining (EDM) field considering 23 years since the first publications. In the digital libraries context, SciBR-M allows the integration of the academy, education, and cultural memory, in relation to a study domain.

Social implications

Cultural changes lead to the production of new knowledge and to the evolution of scientific interest. This knowledge is part of the scientific heritage of society and should be transmitted in a structured and organised form to future generations of scientists and the general public.

Originality/value

The method, based on Formal Concept Analysis, identifies the evolution of scientific interest to a field of study. SciBR-M hierarchically organises bibliographic material to different time periods and explores this hierarchy from proper implication rules. These rules permit identifying recurring themes, i.e. themes subset that received more attention from the scientific community during a specific period. Analysing these rules, it is possible to identify the temporal evolution of scientific interest in the field of study. This evolution is observed by the emergence, increase or decrease of interest in topics in the domain. The SciBR-M method can be used to register and analyse the scientific, cultural heritage of a field of study. In addition, the authors can use the method to stimulate the process of creating knowledge and innovation and encouraging the emergence of new research.

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Article
Publication date: 14 June 2019

Sawan Kumar Rawat, Ashish Mishra and Manoj Kumar

The purpose of this paper is to explore the flow of Cu-water and Ag-water nanofluids past a vertical Riga plate. The plate is infinite in height and has zero normal wall flux…

83

Abstract

Purpose

The purpose of this paper is to explore the flow of Cu-water and Ag-water nanofluids past a vertical Riga plate. The plate is infinite in height and has zero normal wall flux through its surface. Influence of thermal radiation, slip, suction and chemical reaction on the flow characteristics are reported.

Design/methodology/approach

Non-dimensional forms of the flow governing equations are obtained by means of a set of similarity transformations. Numerical solution is obtained with the help of fourth-fifth-order Runge–Kutta–Fehlberg method with shooting procedure. Comparison of solution profiles of Cu-water and Ag-water nanofluids are presented graphically and with the help of tables. Influence of pertinent parameters on skin friction and heat transfer rate is also reported.

Findings

Results reveal that the skin friction coefficient is more prominent in the case of Ag-water nanofluid for an increase in thermal radiation and volume fraction. The role of suction and slip is to increase velocity but decrease the temperature in both nanofluids. Temperature and velocity of both nanofluids increase as volume fraction and thermal radiation values are augmented. Heat transport increases with thermal radiation. Region near the plate experiences rise in nanoparticle concentration with an increase in chemical reaction parameter.

Originality/value

A complete investigation of the modeled problem is addressed and the results of this paper are original.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 4
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 27 June 2008

S. Kiwan and O. Zeitoun

The aim is to study the effects of fin conductivity ratio, Darcy number, and Rayleigh number on the average Nusselt number for fins made of porous material when attached to the…

981

Abstract

Purpose

The aim is to study the effects of fin conductivity ratio, Darcy number, and Rayleigh number on the average Nusselt number for fins made of porous material when attached to the inner cylinder of the annulus between two concentric cylinders. The paper also aims to compare the results with those obtained using solid fins over a range of Rayleigh numbers.

Design/methodology/approach

The Darcy‐Brinkman equations were used to model the fluid flow inside the porous media and the Boussinesq approximation was used to model the buoyancy effect. The energy equation is also solved to find the temperature distribution in the domain of interest. The model equations are solved numerically using a finite volume code.

Findings

Porous fins provided higher heat transfer rates than solid fins for similar configurations. This enhancement in heat transfer reached 75 per cent at Ra=5 × 104 and Da=2.5 × 10−2. It is also found that unlike solid fins the rate of heat transfer from the cylinder equipped with porous fins decreases with increasing the fin inclination angle.

Research limitations/implications

The range of the Rayleigh number considered in this research covers only the laminar regime. The research does not cover turbulent flows. In addition to that, the local thermal equilibrium assumption is used.

Practical implications

This work can help designers in selecting the proper material properties and operating conditions in designing porous fins to enhance the heat transfer in the annulus between two horizontal concentric cylinders under natural convection condition.

Originality/value

This work has not been done before and it can initiate additional research projects as looking at the performance of porous fins under other conditions and configurations (e.g. turbulent conditions).

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 18 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 31 May 2022

Nabi Moradpour, Ahmad Pourahmad, Hossein Hataminejad, Keramatollah Ziari and Ayyoob Sharifi

In Iran, the frequent occurrence of disasters has always been a major problem. In recent decades, disasters have created considerable challenges, especially in cities. Hence…

154

Abstract

Purpose

In Iran, the frequent occurrence of disasters has always been a major problem. In recent decades, disasters have created considerable challenges, especially in cities. Hence, understanding the levels of urban resilience (UR) and planning for addressing vulnerabilities plays a key role in the era of increasing risks and uncertainties. The present study aims to provide a comprehensive overview of the state of resilience of Iranian cities.

Design/methodology/approach

A systematic literature review method was used to determine how resilient Iranian cities are. To find relevant studies, the authors searched Iranian and international databases such as Scopus, ScienceDirect, SID and Magiran. There was no restriction on the inclusion date, meaning that all papers published up until September 16, 2021 were considered for inclusion. The PRISMA framework was used for literature search and selection and, finally, 153 studies focused on 52 cities of Iran were selected for the systematic review.

Findings

In general, the results showed that the level of resilience was low in Iranian cities. Also, informal settlements, worn-out urban fabrics and the central parts of cities showed lower resilience than other parts.

Originality/value

The results of the study can be used to inform municipal authorities, urban planners and non-governmental organizations of the actions that need to be taken to enhance the resilience of Iranian cities.

Details

International Journal of Disaster Resilience in the Built Environment, vol. 14 no. 2
Type: Research Article
ISSN: 1759-5908

Keywords

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