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Article
Publication date: 28 April 2020

Laima Muraliene and Daiva Mikucioniene

Air permeability has a valuable role in comfort parameters. It is known that air permeability of elastomeric yarns is firmly low. Despite that, usage of elastomeric…

Abstract

Purpose

Air permeability has a valuable role in comfort parameters. It is known that air permeability of elastomeric yarns is firmly low. Despite that, usage of elastomeric inlay-yarns is the most common and the most effective way to generate compression for knitted textile. This study aims to investigate the influence of elastomeric inlay-yarn linear density, insertion density and elongation of the sample to the air permeability of compression knitted materials.

Design/methodology/approach

Two different types of knitting patterns were investigated: rib 1 × 1 pattern with different elastomeric inlay-yarn linear density (four variants) and insertion density (without inlay yarn and with inlay-yarns inserted into every single, second or fourth course) and combined laid-in jacquard pattern. The air permeability test for these structures was performed without any deformation and at 10 and 20 per cent fixed transverse elongation.

Findings

According to the investigation, insertion density of inlay-yarns has a huge impact on air permeability; however, air permeability of knitted material is not linearly proportional to the total amount of inlay-yarns. Also, it was found that air permeability increases by increasing elongation, regardless of knitting pattern and total amount of elastomeric inlay-yarn in the knitted structure. Alteration of the loop geometry at natural state and 20 per cent fixed elongation was established, and the increase of air permeability at fixed elongation may be dependent on changes of knitted material porosity.

Originality/value

According to the obtained results, recommendations to perform air permeability measurement at least with minimal specific wear elongation are presented.

Details

International Journal of Clothing Science and Technology, vol. 32 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

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Book part
Publication date: 15 July 2019

Johnna Capitano, Kristie L. McAlpine and Jeffrey H. Greenhaus

A core concept of work–home interface research is boundary permeability – the frequency with which elements from one domain cross, or permeate, the boundary of another…

Abstract

A core concept of work–home interface research is boundary permeability – the frequency with which elements from one domain cross, or permeate, the boundary of another domain. Yet, there remains ambiguity as to what these elements are and how these permeations impact important outcomes such as role satisfaction and role performance. The authors introduce a multidimensional perspective of work–home boundary permeability, identifying five forms of boundary permeation: task, psychological, role referencing, object, and people. Furthermore, based on the notion that employee control over boundary permeability behavior is the key to achieving role satisfaction and role performance, the authors examine how organizations’ HR practices, leadership, and norms impact employee control over boundary permeability in the work and home domains. The authors conclude with an agenda for future research.

Details

Research in Personnel and Human Resources Management
Type: Book
ISBN: 978-1-78973-852-0

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Article
Publication date: 19 May 2021

Zhichao Cheng, Huanling Wang, Weiya Xu and Long Yan

The objective of this paper is to provide a better understanding of the effect of irregular columnar jointed structure on the permeability and flow characteristics of rock masses.

Abstract

Purpose

The objective of this paper is to provide a better understanding of the effect of irregular columnar jointed structure on the permeability and flow characteristics of rock masses.

Design/methodology/approach

An efficient numerical procedure is proposed to investigate the permeability and fluid flow in columnar jointed rock masses (CJRMs), of which the columnar jointed networks are generated by a modified constrained centroid Voronoi algorithm according to the field statistical results. The fractures are represented explicitly by using the lower-dimensional zero thickness elements. And the modeling scheme is validated by a benchmark test for flow in fractured porous media. The effective permeability and representative elementary volume (REV) size of CJRMs are estimated using finite element method (FEM). The influences of joint density and variation coefficient of columnar joint structure on the permeability of the rock mass are discussed.

Findings

The simulation results indicate that the permeability is scale-dependent and tends to be stable with increase of model size. The hydraulic REV size is determined as 3.5 m for CJRMs in the present study. Moreover, the joint density is a dominant factor affecting the permeability of CJRMs. The average permeability of columnar jointed structures increases linearly with the joint density under the same REV size, while the influence from the coefficient of variation can be neglected.

Originality/value

The present paper investigates the REV size of the CJRMs and the effect of joint parameters on the permeability. The proposed method and the results obtained are useful on understanding the hydraulic characteristic of the irregular CJRMs in engineering projects.

Details

Engineering Computations, vol. 38 no. 10
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 8 March 2021

Vijay Kirubakar Raj and Renuka Devi

Parachutes are equipment that is repeatedly used as and when needed. Some of them are used for as many as 60 jumps. The property of the canopy fabric gets deteriorated…

Abstract

Purpose

Parachutes are equipment that is repeatedly used as and when needed. Some of them are used for as many as 60 jumps. The property of the canopy fabric gets deteriorated with use. It is evaluated by destructive tensile and bursting strength. This study aims to focus on the nondestructive evaluation of the canopy fabric's fitness by testing air permeability and relating it with bursting strength. Predictor equations were developed to determine bursting strength from air permeability values.

Design/methodology/approach

ANOVA techniques and statistical regression equations were formed.

Findings

A series of samples containing five parachutes fabrics was used seven times, and their air permeability and bursting strength were determined to find the extent to the effect of reuse of parachute fabrics on their bursting strength and air permeability determination. It was found that there was a progressive drop in bursting strength and an increase in air permeability. An investigation of the extent of determination in terms of bursting strength and an increase in air permeability following the sense of five different types of parachute fabrics is reported.

Research limitations/implications

The work focuses on the prediction of bursting strength to textile materials only and may not apply to other materials like membranes and sheets. The process of determining air permeability is relatively simpler and faster.

Practical implications

The bursting strength can be predicted for used parachutes, which are otherwise subjected to destructive testing.

Social implications

The men using the parachutes can be assured of the superior flawless performance of the parachute as equipment and also contribute to the saving of resources due to nondestructive testing, 100% evaluation of all parachutes is possible.

Originality/value

This article describes the nature of the test procedure and discusses the means of introducing it to users of parachutes. It is accepted that the method must undergo field evaluation and possible modification before it can become a routine tool of parachute using organizations.

Details

International Journal of Clothing Science and Technology, vol. 33 no. 6
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 5 May 2021

Anan Zhang, Jie Yang, Chunhui Ma, Lin Cheng and Liangcai Hu

The purpose of this paper is to form a numerical simulation method for permeability coefficient that can consider the characteristics of gravel gradation and further…

Abstract

Purpose

The purpose of this paper is to form a numerical simulation method for permeability coefficient that can consider the characteristics of gravel gradation and further explore the effects of indoor test factors and gradation characteristics on the permeability coefficient of gravel.

Design/methodology/approach

The random point method is used to establish the polyhedral gravel particle model, the discrete element method (DEM) is used to construct the gravel permeability test sample with gradation characteristics and the finite element method is used to calculate the permeability coefficient to form a DEM-computational fluid dynamics combined method to simulate the gravel seepage characteristics. Then, verified by the indoor test results. Based on this method, the influence of sample size, treatment method of oversize particles and the content of fine particles on the permeability coefficient of gravel is studied.

Findings

For the gravel containing large particles, the larger size permeameter should be used as far as possible. When the permeameter size is limited, the equal weight substitution method is recommended for the treatment method of oversized particles. Compared with the porosity, the pore connectivity has a higher correlation with the permeability coefficient of the sample.

Research limitations/implications

Insufficient consideration of the movement of gravel particles in the seepage process is also an issue for further study.

Originality/value

The simulation method described in this paper is helpful for qualitative analysis, quantitative expression of pore size and makes up for the defect that the seepage characteristics in pores cannot be observed in laboratory tests.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 13 November 2020

Ji Youjun, K. Vafai, Huijin Xu and Liu Jianjun

This paper aims to establish a mathematical model for water-flooding considering the impact of fluid–solid coupling to describe the process of development for a low…

Abstract

Purpose

This paper aims to establish a mathematical model for water-flooding considering the impact of fluid–solid coupling to describe the process of development for a low-permeability reservoir. The numerical simulation method was used to analyze the process of injected water channeling into the interlayer.

Design/methodology/approach

Some typical cores including the sandstone and the mudstone were selected to test the permeability and the stress sensitivity, and some curves of the permeability varying with the stress for the cores were obtained to demonstrate the sensitivity of the formation. Based on the experimental results and the software Eclipse and Abaqus, the main injection parameters to reduce the amount of the injected water in flowing into the interlayer were simulated.

Findings

The results indicate that the permeability of the mudstone is more sensitive to the stress than sandstone. The injection rate can be as high as possible on the condition that no crack is activated or a new fracture is created in the development. For the B82 block of Daqing oilfield, the suggested pressure of the production pressure should be around 1–3MPa, this pressure must be gradually reached to get a higher efficiency of water injection and avoid damaging the casing.

Originality/value

This work is beneficial to ensure stable production and provide technical support to the production of low permeability reservoirs containing an interlayer.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 7 May 2020

Duzhou Zhang, Zhiguo Tian, Zhiqiang Chen, Dengyun Wu, Gang Zhou, Shaohua Zhang and Moran Wang

The purpose of this paper is to investigate the evolution of the permeability of spherical packing during cold compaction by pore-scale modeling.

Abstract

Purpose

The purpose of this paper is to investigate the evolution of the permeability of spherical packing during cold compaction by pore-scale modeling.

Design/methodology/approach

The discrete element method (DEM) is used to generate spherical packing structure under different compressive pressures and the Lattice Boltzmann method (LBM) is adopted to calculate the permeability of each spherical assembly.

Findings

It is found that the decrease of the porosity is the main reason of the reduction in permeability in the initial compression stage, but its influence becomes insufficient in the late compression stages. Besides, two empirical formulas are obtained, which describe the relation between the permeability and the equivalent mean diameter and the variation of normalized permeability with compressive pressure, respectively.

Research limitations/implications

In this study, the authors study the spherical particles and ignore the non-spherical effects. Besides, the classical contact model, the linear-spring-damping model, is used in DEM, so the plastic deformation cannot be considered.

Originality/value

The DEM and the LBM are well combined to study the compaction effects on permeability of spherical packing. Two simple expressions of the spherical packing structure with uniform diameter distribution are given for the first time.

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Article
Publication date: 7 January 2021

Saba Gharehdash, Bre-Anne Louise Sainsbury, Milad Barzegar, Igor B. Palymskiy and Pavel A. Fomin

This research study aims to develop regular cylindrical pore network models (RCPNMs) to calculate topology and geometry properties of explosively created fractures along…

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Abstract

Purpose

This research study aims to develop regular cylindrical pore network models (RCPNMs) to calculate topology and geometry properties of explosively created fractures along with their resulting hydraulic permeability. The focus of the investigation is to define a method that generates a valid geometric and topologic representation from a computational modelling point of view for explosion-generated fractures in rocks. In particular, extraction of geometries from experimentally validated Eulerian smoothed particle hydrodynamics (ESPH) approach, to avoid restrictions for image-based computational methods.

Design/methodology/approach

Three-dimensional stabilized ESPH solution is required to model explosively created fracture networks, and the accuracy of developed ESPH is qualitatively and quantitatively examined against experimental observations for both peak detonation pressures and crack density estimations. SPH simulation domain is segmented to void and solid spaces using a graphical user interface, and the void space of blasted rocks is represented by a regular lattice of spherical pores connected by cylindrical throats. Results produced by the RCPNMs are compared to three pore network extraction algorithms. Thereby, once the accuracy of RCPNMs is confirmed, the absolute permeability of fracture networks is calculated.

Findings

The results obtained with RCPNMs method were compared with three pore network extraction algorithms and computational fluid dynamics method, achieving a more computational efficiency regarding to CPU cost and a better geometry and topology relationship identification, in all the cases studied. Furthermore, a reliable topology data that does not have image-based pore network limitations, and the effect of topological disorder on the computed absolute permeability is minor. However, further research is necessary to improve the interpretation of real pore systems for explosively created fracture networks.

Practical implications

Although only laboratory cylindrical rock specimens were tested in the computational examples, the developed approaches are applicable for field scale and complex pore network grids with arbitrary shapes.

Originality/value

It is often desirable to develop an integrated computational method for hydraulic conductivity of explosively created fracture networks which segmentation of fracture networks is not restricted to X-ray images, particularly when topologic and geometric modellings are the crucial parts. This research study provides insight to the reliable computational methods and pore network extraction algorithm selection processes, as well as defining a practical framework for generating reliable topological and geometrical data in a Eulerian SPH setting.

Details

Engineering Computations, vol. 38 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 6 June 2016

Rajesh Mishra, Arumugam Veerakumar and Jiri Militky

– The purpose of this paper is to investigate effect of material properties in 3D knitted fabrics on thermo-physiological comfort.

Abstract

Purpose

The purpose of this paper is to investigate effect of material properties in 3D knitted fabrics on thermo-physiological comfort.

Design/methodology/approach

In the present study six different spacer fabrics were developed. Among these six fabrics, it was classified into two groups for convenient analysis of results, the first group has been developed using polyester/polypropylene blend with three different proportion and second group with polyester/polypropylene/lycra blend having another three different composition. As a spacer yarn, three different types of 88 dtex polyester monofilament yarn and polyester multifilament yarns (167 dtex and 14.5 tex) were used and 14.5 tex polypropylene and 44 dtex lycra multifilament yarns were also used for the face and back side of the spacer fabrics (Table I). These fabrics were developed in Syntax Pvt Ltd Czech Republic.

Findings

The main influence on the water vapour permeability of warp knitted spacer fabrics is the kind of raw material, i.e. fibre wetting and wicking. Also there is no correlation between air permeability and water vapour permeability. It is found that both air permeability and thermal conductivity are closely related to the fabric density. It is also found that the fabric characteristics of spacer fabric show a very significant effect on the air permeability, thermal conductivity and mechanical properties of spacer fabric. Therefore, selection of spacer fabric for winter clothing according to its fabric characteristics.

Practical implications

The main objective of the present study is to produce spacer knitted 3D fabrics suitable for defined climatic conditions to be used as clothing or in sports goods.

Originality/value

New 3D knitted spacer fabrics can be produced with improved comfort properties.

Details

International Journal of Clothing Science and Technology, vol. 28 no. 3
Type: Research Article
ISSN: 0955-6222

Keywords

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Article
Publication date: 20 May 2019

Leila Mechkarini, Tahar Messafer, Abderrahim Bali and Kamel Silhadi

Prediction models for the unsaturated permeability proposed in the literature are numerous. However, a model may give a good result for a sample of a given soil when it…

Abstract

Purpose

Prediction models for the unsaturated permeability proposed in the literature are numerous. However, a model may give a good result for a sample of a given soil when it may give a bad result for another sample belonging to the same type of soil. This showed that the choice of a model to complete the permeability curve in the unsaturated state is complex. To facilitate such studies, this paper aims to present a help system capable of defining the mathematical model to the user that best represents the permeability of the soil.

Design/methodology/approach

The authors have detailed the difficulties in determining the correct value of kuns from a thorough bibliographic study. To develop this idea, the authors took real examples, to which they applied mathematical models and then compared their results with those of the bibliographic study. Knowledge structuring in the form of classes, rules and functions. Implementation of the data in generator of help system Kappa-pc. validation of results.

Findings

An aid tool was developed for the evaluation of unsaturated soils permeability using Brooks and Corey (1964) and Leong and Rahardjo (1997) models, which are known for their effectiveness and ease of application. This system will also evaluate these two methods using estimation models of saturated permeability [Dane and Pocket (1992), Terzaghi (1981) and laboratory data]. This system allows the evaluation of unsaturated permeability by the aforementioned two models, makes comparison between these two models, classifies them and proposes the model presenting the best result.

Originality/value

This aid system is able to compare results of different models of prediction of the hydraulic conductivity of unsaturated soils according to several criteria (suction, degree of saturation, plasticity index, models of estimation of the permeability to the soil, saturated state, particle size, etc.). It can also deduce the model that best adapts to a given soil. This aid system will be of great use for geotechnical engineers and researchers in the field.

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