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Article
Publication date: 12 October 2020

Saeed Hasanpoor, Zahra Mansourpour and Navid Mostoufi

The purpose of this paper is to fundamentally develop a mathematical model for predicting the particle size distribution (PSD) in fluidized beds because their…

Abstract

Purpose

The purpose of this paper is to fundamentally develop a mathematical model for predicting the particle size distribution (PSD) in fluidized beds because their hydrodynamics depend on the PSD and its evolution during operation. To predict the gradual PSD change in a fluidized bed by using the population balance method (PBM), the kinetic parameter for agglomerate formation should be known and this parameter, in this work, is determined by the results of computational fluid dynamic–discrete element method (CFD-DEM) simulation.

Design/methodology/approach

Momentum and energy conservation equations and soft-sphere DEM are used to simulate the agglomeration phenomenon at high temperature in a two-dimensional air-polyethylene fluidized bed in bubbling regime. The Navier–Stokes equations for motion of gas are solved by the SIMPLE algorithm. Newton’s second law of motion is applied to describe the motion of individual particles. Collision between particles is detected by the no-binary search algorithm.

Findings

A correlation is proposed for estimating the kinetic parameter for agglomerate formation based on collision frequency, collision efficiency and inlet gas temperature. Based on the corrected kinetic parameter, the PBM is able to predict the PSD evolution in the fluidized bed in a fairly good agreement with the results of the CFD-DEM.

Research limitations/implications

The results of the agglomeration process cannot be compared quantitatively with experimental results. Because three-dimensional fluidized bed mostly contains millions of particles and simulating them takes a long computing time in DEM. As far as temperature is a dominant parameter in the agglomeration process, effects of inlet gas temperature are examined on the kinetic parameter. On the other hand, wider and deeper insights in which the effect of other parameters, such as velocity and so on will be studied, is one of the goals in the authors’ next works to compensate for the shortcomings in this work.

Originality/value

This study helps to understand the effect of the inlet gas temperature during the agglomeration process on the kinetic parameter and provides fundamental information in dealing with kinetic parameter to attain PSD in fluidized bed by the PBM.

Details

Engineering Computations, vol. 38 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 3 August 2015

Kung-Jen Tu

The purpose of this study is to present the theoretical framework of the “data envelopment analysis (DEA) Energy Management System (DEMS)” proposed to assist individual…

Abstract

Purpose

The purpose of this study is to present the theoretical framework of the “data envelopment analysis (DEA) Energy Management System (DEMS)” proposed to assist individual departments occupying the same buildings on university campus in assessing the energy efficiencies of their facilities, as well as to demonstrate the implementation results of the DEMS applied in the case of the Department of Architecture of NTUST in Taiwan.

Design/methodology/approach

The proposed DEMS considers each “space” within a department in a given “time” (such as a month) as a decision-making unit (DMU). Then, regression analysis is performed on data of “existing environment”, “occupancy” factors and “actual energy consumption EUI (energy usage intensity)” related variables. The regression equation derived is then used to calculate the “predicted EUI” for all DMUs. The “actual EUI” is further considered as the input data and the “predicted EUI” as the output data of the DEMS, on which data envelopment analysis is conducted to produce three types of energy-efficiency scores (overall efficiency, scale efficiency, pure technical efficiency) to indicate the energy efficiencies of all DMUs.

Findings

The DEMS was developed and further implemented in the Department of Architecture of NTUST in Taiwan to illustrate how it can be used to assist individual departments within universities in assessing the energy management effectiveness of their spaces.

Research limitations/implications

The accuracy of the energy-efficiency scores depends greatly on the accuracy of the predicted EUIs of spaces, and, therefore, it is critical to identify a better regression model with higher predictability (R2). The relatively low actual EUIs of certain student spaces during winter and summer breaks may greatly affect the resulting energy-efficiency scores.

Practical implications

The DEMS allows facility managers to assess and compare the energy-efficiency scores “among different spaces”, to further review the energy efficiency of a space “over time” and to recognize the benchmark cases and pursue actions for energy improvement.

Originality/value

This study explores the research concepts of “space type” and “internal benchmark” with an analytical method “data envelopment analysis” to assess the energy efficiency of an individual department which may only occupy certain floors of a building.

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Article
Publication date: 27 April 2020

Jiale Lu, Baofeng Pan, Tiankai Che and Dong Sha

This study aims to investigate the influence of surface texture distribution in respect to the procedure of pavement surface wear on friction performance.

Abstract

Purpose

This study aims to investigate the influence of surface texture distribution in respect to the procedure of pavement surface wear on friction performance.

Design/methodology/approach

The Weierstrass–Mandelbrot (W-M) equation is used to appropriate pavement surface profile. Through this approximation, artificial rough profiles by combining fractal parameters and conventional statistical parameters for different macro-texture are created to simulate the procedure of pavement surface wear. Those artificial profiles are then imported into discrete element model to calculate the interaction forces and friction coefficient between rolling tire and road. Furthermore, wavelet theory is used to decompose the profiles into different scales and explore the correlation between the profiles of each scale and pavement friction.

Findings

The influence of tire vertical displacement (TVD) on friction coefficient is greater than fractal dimension of road surface texture. When TVD decreases, the profiles can provide higher friction, but the rolling stability of tire is poor. The optimal fractal dimension of road surface is about 1.5 when considering friction performance. The pavement friction performance improves with wavelength from 0.4 to 6.4mm and decreases with wavelength from 12.8 to 51.2mm.

Originality/value

Artificial fractal curves are generated and analyzed by combining W-M function with traditional parameter, which can also be used to analyze the influence of texture distribution on other pavement performance. The preliminary research provides a potential approach for the evaluation of pavement friction performance.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2019-0499/

Details

Industrial Lubrication and Tribology, vol. 72 no. 7
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 February 1992

PETER A. CUNDALL and ROGER D. HART

Discrete element methods are numerical procedures for simulating the complete behaviour of systems of discrete, interacting bodies. Three important aspects of discrete…

Abstract

Discrete element methods are numerical procedures for simulating the complete behaviour of systems of discrete, interacting bodies. Three important aspects of discrete element programs are examined: (1) the representation of contacts; (2) the representation of solid material; and (3) the scheme used to detect and revise the set of contacts. A proposal is made to define what constitutes a discrete element program, and four classes of such programs are described: the distinct element method, modal methods, discontinuous deformation analysis and the momentum‐exchange method. Several applications and examples are presented, and a list is given of suggestions for future developments.

Details

Engineering Computations, vol. 9 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 1 February 2004

Sharifah N. Syed Omar, Faisal kh. M. Jeber and Shattri Mansor

Remote sensing data and GIS techniques have been used to create thematic maps for assessment and estimation of landslide hazards, in Pos Slim‐Cameron Highlands area…

Abstract

Remote sensing data and GIS techniques have been used to create thematic maps for assessment and estimation of landslide hazards, in Pos Slim‐Cameron Highlands area, Peninsula Malaysia. The Landsat TM5 scene was used to extract land use parameter of the study area. The digital elevation model (DEM) was generated from digitised topographic maps to produce slope risk map, aspect risk map and height risk map. From these data, a simple algorithm is created to classify the area into different risk zones. By overlaying all hazard maps, a final hazard map is produced. The integration of GIS with remotely sensed data might greatly facilitate classifying landslide areas to three categories; low risk, medium risk and high risk.

Details

Disaster Prevention and Management: An International Journal, vol. 13 no. 1
Type: Research Article
ISSN: 0965-3562

Keywords

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Book part
Publication date: 10 April 2019

Abstract

Details

Diversity within Diversity Management
Type: Book
ISBN: 978-1-78754-821-3

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Article
Publication date: 6 June 2019

Ali Bassam Mahmoud, Nicholas Grigoriou, Leonora Fuxman, Dieu Hack-Polay, Fatina Bassam Mahmoud, Eiad Yafi and Shehnaz Tehseen

This study aims to assess consumers’ beliefs in three Middle Eastern Arab countries regarding attitudinal and behavioural responses towards permission-based direct email…

Abstract

Purpose

This study aims to assess consumers’ beliefs in three Middle Eastern Arab countries regarding attitudinal and behavioural responses towards permission-based direct email marketing (hereafter DEM) and the moderating role of gender in the hypothesised path model.

Design/methodology/approach

Structural equation modelling was used to test the hypothesised path model by using data collected from 829 respondents.

Findings

The findings show that attitude was found to fully mediate the relationship between beliefs and behavioural responses towards permission-based DEM. Gender moderates the relationship between beliefs and attitudes and responses to permission-based DEM. Notably, female respondents were found to react more actively when exposed to permission-based DEM.

Research limitations/implications

Further qualitative research is needed to learn more about how and why individuals develop behavioural intentions in certain ways towards opt-in DEM. In addition, neuropsychology approaches such as eye-tracking are endorsed for future research to gain more insights and conquer biases associated with self-reporting procedures in countries where such technologies are deemed as legal and ethical to be used with human subjects.

Practical implications

Advertisers promoting products and services in the Middle Eastern Arab context should take further steps to enhance the quality of information (including cultural sensitiveness) and the perceived entertainment value that could be delivered to consumers through permission-based DEM, especially for female internet users. Additionally, this study highly recommends the double opt-in approach to permission-based DEM.

Originality/value

To the best of the authors’ knowledge, this is the first attempt to address the gender role as a moderator of the path depicting the effectiveness of permission-based DEM approach in the Middle East (Arab counties) from beliefs to behavioural responses via attitudes.

Details

Journal of Research in Interactive Marketing, vol. 13 no. 2
Type: Research Article
ISSN: 2040-7122

Keywords

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Article
Publication date: 21 August 2009

Jiansheng Xiang, Antonio Munjiza, John‐Paul Latham and Romain Guises

As particulate systems evolve, sliding, rolling and collision contacts all produce forces that discrete element method (DEM) methods aim to predict. Verification of…

Abstract

Purpose

As particulate systems evolve, sliding, rolling and collision contacts all produce forces that discrete element method (DEM) methods aim to predict. Verification of friction rarely takes high priority in validation studies even though friction plays a very important role in applications and in mathematical models for numerical simulation. The purpose of this paper is to address sliding friction in finite element method (FEM)/DEM and rolling friction in DEM.

Design/methodology/approach

Analytical solutions for “block sliding” were used to verify the authors' tangential contact force implementation of 2D FEM/DEM. Inspired by the kinetic art work Liquid Reflections by Liliane Lijn, which consists of free balls responding within a rotating shallow dish, DEM was used to simulate rolling, sliding and state‐of‐rest of spherical particles relative to horizontal and inclined, concave and flat spinning platforms. Various material properties, initial and boundary conditions are set which produce different trajectory regimes.

Findings

Simulation output is found to be in excellent agreement when compared with experimental results and analytical solutions.

Originality/value

The more widespread use of analytically solvable benchmark tests for DEM and FEM/DEM codes is recommended.

Details

Engineering Computations, vol. 26 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 4 September 2018

Juan Luis Osa, Naiara Ortega, Gorka Vidal, Borja Fernandez-Gauna, Asier Carballo and Ibon Tolosa

The granular structure of a grinding wheel determines its performance remarkably when grinding. Nowadays, grinding wheels are man-made porous conglomerates of hard…

Abstract

Purpose

The granular structure of a grinding wheel determines its performance remarkably when grinding. Nowadays, grinding wheels are man-made porous conglomerates of hard abrasive grains bonded with a binder. As an engineered material, it would be interesting to foresee the behaviour of the wheel, but it is hindered under its complex heterogeneous nature. Recently, some models based on the discrete element method (DEM) have been presented to model the grinding wheel. This paper aims to identify and propose a framework that must comply with such models and to identify new applications for DEM models in grinding.

Design/methodology/approach

First, the characteristics of the grinding wheel are described. In this way, the framework of DEM models of a grinding wheel material is developed, reproducing both the granular morphology and stiffness.

Findings

The paper asserts a promising future that provides the DEM in the modelling of grinding.

Originality/value

The potential of DEM in grinding is analysed, proposing new applications. It can be used as topography model, which can also model the stiffness. In addition, DEM opens a new interesting research line: the modelling of the grit breakout. It draws up the development of essential dressing and wear models.

Details

Engineering Computations, vol. 35 no. 6
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 5 April 2011

Andrew Phillip Grima and Peter Wilhelm Wypych

The purpose of this paper is to examine several calibration techniques that have been developed to determine the discrete element method (DEM) parameters for slow and…

Abstract

Purpose

The purpose of this paper is to examine several calibration techniques that have been developed to determine the discrete element method (DEM) parameters for slow and rapid unconfined flow of granular conical pile formation. This paper also aims to discuss some of the methods currently employed to scale particle properties to reduce computational resources and time to solve large DEM models.

Design/methodology/approach

DEM models have been calibrated against simple bench‐scale experimental results to examine the validity of selected parameters for the contact, material and mechanical models to simulate the dynamic and static behaviour of cohesionless polyethylene pellets. Methods to determine quantifiable single particle parameters such as static friction and the coefficient of restitution have been highlighted. Numerical and experimental granular pile formation has been investigated using different slumping and pouring techniques to examine the dependency of the type of flow mechanism on the DEM parameters.

Findings

The proposed methods can provide cost effective and simple techniques to determine suitable input parameters for DEM models. Rolling friction and particle shape representation has shown to have a significant influence on the bulk flow characteristics via a sensitivity analysis and needs to be accessed based on the environmental conditions.

Originality/value

This paper describes several effective known and novel methodologies to characterise granular materials that are needed to accurately model granular flow using the DEM to provide valuable quantitative data. For the DEM to be a viable predictive tool in industrial applications which often contain huge quantities of particles with random particle shapes and irregular properties, quick and validated techniques to “tune” DEM models are necessary.

Details

Engineering Computations, vol. 28 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

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