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Article
Publication date: 13 March 2007

K. Han, Y.T. Feng and D.R.J. Owen

The main purpose of this paper is to compare the performance of three commonly used global search algorithms, namely tree‐based augmented spatial digital tree, cell‐based…

Abstract

Purpose

The main purpose of this paper is to compare the performance of three commonly used global search algorithms, namely tree‐based augmented spatial digital tree, cell‐based no binary search and D‐cell, in the discrete element simulations.

Design/methodology/approach

A large number of test cases with up to five million particles/discrete objects are employed to numerically examine the computational costs of the three search algorithms and their performance is compared.

Findings

Comprehensive comparisons reveal that the D‐cell is more efficient than the tree‐based search algorithms for large‐scale problems. The parametric study of the D‐cell algorithm itself shows that the performance of the algorithm is strongly dependent on the cell dimension chosen.

Research limitations/implications

The only limitation of the current work is that the tested domain shape is regular, and thus more complex domain shapes may need to be considered.

Originality/value

The paper provides clear guidance regarding the possible actual computational performance of the tested search algorithms for practical applications.

Details

Engineering Computations, vol. 24 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 28 November 2019

Tingting Zhao, Y.T. Feng and Yuanqiang Tan

The purpose of this paper is to extend the previous study [Computer Methods in Applied Mechanics and Engineering 340: 70-89, 2018] on the development of a novel packing…

Abstract

Purpose

The purpose of this paper is to extend the previous study [Computer Methods in Applied Mechanics and Engineering 340: 70-89, 2018] on the development of a novel packing characterising system based on principal component analysis (PCA) to quantitatively reveal some fundamental features of spherical particle packings in three-dimensional.

Design/methodology/approach

Gaussian quadrature is adopted to obtain the volume matrix representation of a particle packing. Then, the digitalised image of the packing is obtained by converting cross-sectional images along one direction to column vectors of the packing image. Both a principal variance (PV) function and a dissimilarity coefficient (DC) are proposed to characterise differences between different packings (or images).

Findings

Differences between two packings with different packing features can be revealed by the PVs and DC. Furthermore, the values of PV and DC can indicate different levels of effects on packing caused by configuration randomness, particle distribution, packing density and particle size distribution. The uniformity and isotropy of a packing can also be investigated by this PCA based approach.

Originality/value

Develop an alternative novel approach to quantitatively characterise sphere packings, particularly their differences.

Details

Engineering Computations, vol. 37 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 27 August 2019

Y.T. Feng and Yuanqiang Tan

Contact detection for convex polygons/polyhedra has been a critical issue in discrete/discontinuous modelling, such as the discrete element method (DEM) and the…

Abstract

Purpose

Contact detection for convex polygons/polyhedra has been a critical issue in discrete/discontinuous modelling, such as the discrete element method (DEM) and the discontinuous deformation analysis (DDA). The recently developed 3D contact theory for polyhedra in DDA depends on the so-called entrance block of two polyhedra and reduces the contact to evaluate the distance between the reference point to the corresponding entrance block, but effective implementation is still lacking.

Design/methodology/approach

In this paper, the equivalence of the entrance block and the Minkowski difference of two polyhedra is emphasised and two well-known Minkowski difference-based contact detection and overlap computation algorithms, GJK and expanding polytope algorithm (EPA), are chosen as the possible numerical approaches to the 3D contact theory for DDA, and also as alternatives for computing polyhedral contact features in DEM. The key algorithmic issues are outlined and their important features are highlighted.

Findings

Numerical examples indicate that the average number of updates required in GJK for polyhedral contact is around 6, and only 1 or 2 iterations are needed in EPA to find the overlap and all the relevant contact features when the overlap between polyhedra is small.

Originality/value

The equivalence of the entrance block in DDA and the Minkowski difference of two polyhedra is emphasised; GJK- and EPA-based contact algorithms are applied to convex polyhedra in DEM; energy conservation is guaranteed for the contact theory used; and numerical results demonstrate the effectiveness of the proposed methodologies.

Details

Engineering Computations, vol. 37 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 15 June 2015

Yuanqiang Tan, Rong Deng, Y T Feng, Hao Zhang and Shengqiang Jiang

The purpose of this paper is to establish a new two-phase Discrete Element Method (DEM) model to investigate the movement of fresh concrete which consists of mortar and…

Abstract

Purpose

The purpose of this paper is to establish a new two-phase Discrete Element Method (DEM) model to investigate the movement of fresh concrete which consists of mortar and aggregate. The established DEM model was adopted to simulate the mixing process of fresh concrete based on the commercial software package PFC3D. The trajectories of particles and particle clusters were recorded to analyze the mixing behavior from different scales. On one hand, the macro-scale movement was obtained to make the mixing process visualization. On the other hand, the relative micro movement of the single particle and particle clusters was also monitored to further study the mixing mechanism of the fresh concrete.

Design/methodology/approach

A new two-phase DEM model was designed to simulate the movement of fresh concrete which consists of mortar and aggregate. The linear-spring dashpot model was used to model all the contacts between particle and particle/wall to characterize the viscidity of fresh concrete. Moreover, two sets of parallel bond models were employed to characterize the contact between the mortar particles and mortar/coarse aggregate particles, namely the pbond1 and pbond2. The hybrid treatment enables the current DEM model to handle the yield behavior.

Findings

The mixing process of fresh concrete is mainly composed by the transportation in the x-direction and the overturn and fall off in the y- and z-directions. With these movements in different directions, the concrete particles can be fully mixed in the mixing drum.

Originality/value

A new two-phase DEM model was proposed and used to simulate the mixing process of fresh concrete. The outcomes of the simulation would be helpful for making the transporting truck visualization and the movement behavior of fresh concrete observable. The model can provide dynamic information of particles to reveal the interaction mechanism of fresh concrete in the truck mixer which is extremely difficult to obtain on-line in physical experiments or building site.

Details

Engineering Computations, vol. 32 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 6 March 2017

Yuxiu Yan, Yanna Feng, Zimin Jin and Jianwei Tao

The purpose of this paper is to improve the comfort and shaping function of seamless shapewear on the material and structure and develop new seamless shapewear products…

Abstract

Purpose

The purpose of this paper is to improve the comfort and shaping function of seamless shapewear on the material and structure and develop new seamless shapewear products. The shaping figure effect will be verified as well.

Design/methodology/approach

The performance of the knitted fabrics made of Polytrimethylene terephthalate (PTT) filament was analyzed by orthogonal experiment and fuzzy mathematical methods analysis, in order to get the optimal conditions for the best performance. The new products were designed and made based on the results of the material research with the consideration of the aesthetic requirements. The shaping effect of seamless shapewears on local and global figure was tested by the methods of the combination of subjective and objective evaluation.

Findings

The sample which renders the optimal performance for shapewear is the one with PTT filament as face yarn, nylon core-spun yarn as ground yarn and 3+1 simulate rib knit structure. The material of face yarn, mixed proportion and structure can influence the shape retention, appearance and comfort of PTT fabric in various degrees. Three shapewears which were developed according to the results of material research have different shaping effect. And women with different figures put different satisfaction degrees on each shapewear’s shaping effect.

Practical implications

This paper provides scientific basis and reference for enterprise to design good tight seamless shapewear as well as for consumer to buy suitable products.

Originality/value

In the view of the problems of present shapewears, this paper completed the development of the shapewears and verified the shaping effect of them on women with different figures. The shapewears can be put into production directly.

Details

International Journal of Clothing Science and Technology, vol. 29 no. 1
Type: Research Article
ISSN: 0955-6222

Keywords

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Book part
Publication date: 11 July 2019

Carl Lin and Yana van der Meulen Rodgers

This study uses migrant household survey data from 2008 to 2009 to examine how parental migration decisions are associated with the nutritional status of children in rural…

Abstract

This study uses migrant household survey data from 2008 to 2009 to examine how parental migration decisions are associated with the nutritional status of children in rural and urban China. Results from instrumental variables regressions show a substantial adverse effect of children’s exposure to parental migration on height-for-age Z scores of left-behind children relative to children who migrate with their parents. Additional results from a standard Blinder–Oaxaca decomposition, a quantile decomposition, and a counterfactual distribution analysis all confirm that children who are left behind in rural villages – usually because of the oppressive hukou system – have poorer nutritional status than children who migrate with their parents, and the gaps are biggest at lower portions of the distribution.

Details

Health and Labor Markets
Type: Book
ISBN: 978-1-78973-861-2

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Article
Publication date: 19 March 2018

Junying Liu, Sen Lin and Yingbin Feng

Construction insurance has been advocated as a useful financial means to transfer risks and mitigate potential project losses. However, there is a general reluctance to…

Abstract

Purpose

Construction insurance has been advocated as a useful financial means to transfer risks and mitigate potential project losses. However, there is a general reluctance to purchase construction insurance in China. The purpose of this paper is to develop an extended theory of planned behavior (TPB) model to understand and predict contractors’ construction insurance purchasing intention.

Design/methodology/approach

Quantitative data were collected through a questionnaire survey. The respondents comprise 130 project directors/managers and contract managers/administrators who were involved in or familiar with the construction insurance purchasing or managing. Data were analyzed using structural equation modeling.

Findings

This study developed an extended TPB model to explain the contractors’ intention formation. The results indicated that the insurance purchasing intention was mainly influenced by attitudes and subjective norm, rather than perceived behavioral control. The analyses also revealed that the added variables (risk perception and past experience) had a significant impact on the attitudes and perceived behavioral control.

Originality/value

This study identified the factors leading to Chinese contractors’ low willingness to purchase construction insurance by extending the TPB model to the context of construction insurance purchasing. The extended TPB model may serve as a theoretical framework and basis for the Chinese contractors, insurers, and regulators to understand the root causes of contractors’ low willingness to purchase construction insurance and make joint efforts to address the risks and insurance in the construction industry.

Details

Engineering, Construction and Architectural Management, vol. 25 no. 2
Type: Research Article
ISSN: 0969-9988

Keywords

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Article
Publication date: 24 January 2019

Min Wang, Y.T. Feng, Ting T. Zhao and Yong Wang

Sand production is a challenging issue during hydrocarbon production in the oil and gas industry. This paper aims to investigate one sand production process, i.e…

Abstract

Purpose

Sand production is a challenging issue during hydrocarbon production in the oil and gas industry. This paper aims to investigate one sand production process, i.e. transient sand production, using a novel bonded particle lattice Boltzmann method. This mesoscopic technique provides a unique insight into complicated sand erosion process during oil exploitation.

Design/methodology/approach

The mesoscopic fluid-particle coupling is directly approached by the immersed moving boundary method in the framework of lattice Boltzmann method. Bonded particle method is used for resolving the deformation of solid. The onset of grain erosion of rocks, which are modelled by a bonded particle model, is realised by breaking the bonds simulating cementation when the tension or tangential force exceeds critical values.

Findings

It is proved that the complex fluid–solid interaction occurring at the pore/grain level can be well captured by the immersed moving boundary scheme in the framework of the lattice Boltzmann method. It is found that when the drawdown happens at the wellbore cavity, the tensile failure area appears at the edge of the cavity. Then, the tensile failure area gradually propagates inward, and the solid particles at the tensile failure area become fluidised because of large drag forces. Subsequently, some eroded particles are washed out. This numerical investigation is demonstrated through comparison with the experimental results. In addition, through breaking the cementation, which is simulated by bond models, between bonded particles, the transient particle erosion process is successfully captured.

Originality/value

A novel bonded particle lattice Boltzmann method is used to investigate the sand production problem at the grain level. It is proved that the complex fluid–solid interaction occurring at the pore/grain level can be well captured by the immersed moving boundary scheme in the framework of the lattice Boltzmann method. Through breaking the cementation, which is simulated by bond models, between bonded particles, the transient particle erosion process is successfully captured.

Details

Engineering Computations, vol. 36 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 December 2005

Xikui Li, Xihua Chu and Y.T. Feng

To present a discrete particle model for granular materials.

Abstract

Purpose

To present a discrete particle model for granular materials.

Design/methodology/approach

Starting with kinematical analysis of relative movements of two typical circular grains with different radii in contact, both the relative rolling and the relative sliding motion measurements at contact, including translational and angular velocities (displacements) are defined. Both the rolling and sliding friction tangential forces, and the rolling friction resistance moment, which are constitutively related to corresponding relative motion measurements defined, are formulated and integrated into the framework of dynamic model of the discrete element method.

Findings

Numerical results demonstrate that the importance of rolling friction resistance, including both rolling friction tangential force and rolling friction resistance moment, in correct simulations of physical behavior in particulate systems; and the capability of the proposed model in simulating the different types of failure modes, such as the landslide (shear bands), the compression cracking and the mud avalanching, in granular materials.

Research limitations/implications

Each grain in the particulate system under consideration is assumed to be rigid and circular. Do not account for the effects of plastic deformation at the contact points.

Practical implications

To model the failure phenomena of granular materials in geo‐mechanics and geo‐technical engineering problems; and to be a component model in a combined discrete‐continuum macroscopic approach or a two‐scale discrete‐continuum micro‐ macro‐scopic approach to granular media.

Originality/value

This paper develops a new discrete particle model to describe granular media in several branches of engineering such as soil mechanics, power technologies or sintering processes.

Details

Engineering Computations, vol. 22 no. 8
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 9 October 2019

Qinjun Liu, Gui Ye and Yingbin Feng

Although research on prefabricated construction has gained increasing attention in recent years, limited efforts have been devoted to investigating safety issues in the…

Abstract

Purpose

Although research on prefabricated construction has gained increasing attention in recent years, limited efforts have been devoted to investigating safety issues in the off-site manufacture, especially workers’ behavioral intentions to work safely. Thus, research is needed to identify the motivational factors determining off-site construction workers’ safety behaviors. The purpose of this paper is to investigate workers’ safety behavior by examining the determinants of behavioral intention in the off-site manufacturing plants in China.

Design/methodology/approach

Theory of planned behavior (TPB) was modified and used in this study to explain how the elements in the hypothesized model interact. Data were collected using a questionnaire. Structural equation modeling technique with partial least-squares estimation was used to analyze the data collected.

Findings

The findings of this study indicated that workers’ tendency to engage in safety behavior is positively related to attitude toward the behavior, subjective norm, perceived behavioral control and behavioral habit, among which attitude toward the behavior and behavioral habit have most significant influences on safety behavior. This finding provides a better explanation on the pathways and the impacts of the crucial factors on the safety behaviors for the off-site manufacture.

Originality/value

The possible innovation of this research lies in its attempt to understand the antecedents of workers’ safety behavior in the off-site construction environment, which may make original contributions to construction safety research and practice. The findings of this study contribute to the body of knowledge in TPB. Corresponding countermeasures are put forward in order to improve workers’ safety behavior in off-site construction.

Details

Engineering, Construction and Architectural Management, vol. 27 no. 3
Type: Research Article
ISSN: 0969-9988

Keywords

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