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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

Book part
Publication date: 25 April 2022

Afikah Binti Rahim, Taslim Maulana, Ferian Anggara and Mohammed Hail Hakimi

Cleats are considered one of the significant permeability-related parameters in coalbed methane (CBM) growth. As critical parameters for CBM extraction, a complete

Abstract

Cleats are considered one of the significant permeability-related parameters in coalbed methane (CBM) growth. As critical parameters for CBM extraction, a complete characterisation of cleat distributions and orientation can provide a better tool to indirectly estimate porosity and permeability in coal reservoirs. This chapter presents the outcomes of the production of comprehensive research cleats within Miocene coal seams as part of CBM exploration and development. The majority of data (cross-section view measurement) were collected on mine’s walls. Cleat data were gathered from 16 windows measurement locations with hundreds of cleats were measured from outcrops for several coal seams. Two primary cleat orientations; for face cleats, NNE-SSW and for butt cleats, ESE-WNW. The ratio of low permeability coals appears to have a smaller cleat aperture than high permeability coals. As critical parameters for CBM extraction, a complete characterisation of cleat distributions and orientation can provide a better tool to indirectly estimate porosity and permeability in coal reservoirs.

Details

Sustainability Management Strategies and Impact in Developing Countries
Type: Book
ISBN: 978-1-80262-450-2

Keywords

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

Keywords

Article
Publication date: 29 August 2022

Jurgita Lazauskaite-Zabielske, Arunas Ziedelis and Ieva Urbanaviciute

Drawing on boundary theory, this study aims to analyse whether the intensity of working from home will be related to higher exhaustion through family boundary permeability

Abstract

Purpose

Drawing on boundary theory, this study aims to analyse whether the intensity of working from home will be related to higher exhaustion through family boundary permeability, with this relationship being more robust when overwork climate is high.

Design/methodology/approach

In this paper eight hundred eighty-three white-collar employees working from home during the COVID-19 pandemic in Lithuania were surveyed online.

Findings

The results confirmed the hypotheses, demonstrating that family boundary permeability may explain the relationship between telework intensity and exhaustion. Furthermore, the mediating relationship between the intensity of working from home, family boundary permeability and exhaustion were moderated by overwork climate. Employees who felt the pressure to overwork were more likely to have a more permeable family boundary when working from home and appeared to experience a much higher psychological cost in terms of emotional exhaustion.

Originality/value

The study provides an insight into the relationships between the intensity of working from home, boundary permeability and exhaustion and their boundary conditions when working from home during the COVID-19 pandemic.

Details

Baltic Journal of Management, vol. 17 no. 5
Type: Research Article
ISSN: 1746-5265

Keywords

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

Keywords

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

Keywords

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

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.

Article
Publication date: 30 January 2007

Ahmet Çay, Savvas Vassiliadis, Maria Rangoussi and Işık Tarakçıoğlu

The target of the current work is the creation of a model for the prediction of the air permeability of the woven fabrics and the water content of the fabrics after the…

1379

Abstract

Purpose

The target of the current work is the creation of a model for the prediction of the air permeability of the woven fabrics and the water content of the fabrics after the vacuum drying.

Design/methodology/approach

There have been produced 30 different woven fabrics under certain weft and warp densities. The values of the air permeability and water content after the vacuum drying have been measured using standard laboratory techniques. The structural parameters of the fabrics and the measured values have been correlated using techniques like multiple linear regression and Artificial Neural Networks (ANN). The ANN and especially the generalized regression ANN permit the prediction of the air permeability of the fabrics and consequently of the water content after vacuum drying. The performance of the related models has been evaluated by comparing the predicted values with the respective experimental ones.

Findings

The predicted values from the nonlinear models approach satisfactorily the experimental results. Although air permeability of the textile fabrics is a complex phenomenon, the nonlinear modeling becomes a useful tool for its prediction based on the structural data of the woven fabrics.

Originality/value

The air permeability and water content modeling support the prediction of the related physical properties of the fabric based on the design parameters only. The vacuum drying performance estimation supports the optimization of the industrial drying procedure.

Details

International Journal of Clothing Science and Technology, vol. 19 no. 1
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 26 October 2018

Tharmalingam Sivarupan, Mohamed El Mansori, Keith Daly, Mark Noel Mavrogordato and Fabrice Pierron

Micro-focus X-ray computed tomography (CT) can be used to quantitatively evaluate the packing density, pore connectivity and provide the basis for specimen derived…

Abstract

Purpose

Micro-focus X-ray computed tomography (CT) can be used to quantitatively evaluate the packing density, pore connectivity and provide the basis for specimen derived simulations of gas permeability of sand mould. This non-destructive experiment or following simulations can be done on any section of any size sand mould just before casting to validate the required properties. This paper aims to describe the challenges of this method and use it to simulate the gas permeability of 3D printed sand moulds for a range of controlling parameters. The permeability simulations are compared against experimental results using traditional measurement techniques. It suggests that a minimum volume of only 700 × 700 × 700 µm3 is required to obtain, a reliable and most representative than the value obtained by the traditional measurement technique, the simulated permeability of a specimen.

Design/methodology/approach

X-ray tomography images were used to reconstruct 3D models to simulate them for gas permeability of the 3D printed sand mould specimens, and the results were compared with the experimental result of the same.

Findings

The influence of printing parameters, especially the re-coater speed, on the pore connectivity of the 3D printed sand mould and related permeability has been identified. Characterisation of these sand moulds using X-ray CT and its suitability, compared to the traditional means, are also studied. While density and 3PB strength are a measure of the quality of the moulds, the pore connectivity from the tomographic images precisely relates to the permeability. The main conclusions of the present study are provided below. A minimum required sample size of 700 × 700 × 700 µm3 is required to provide representative permeability results. This was obtained from sand specimens with an average sand grain size of 140 µm, using the tomographic volume images to define a 3D mesh to run permeability calculations. Z-direction permeability is always lower than that in the X-/Y-directions due to the lower values of X-(120/140 µm) and Y-(101.6 µm) resolutions of the furan droplets. The anisotropic permeability of the 3D printed sand mould is mainly due to, the only adjustable, X-directional resolution of the furan droplets; the Y-directional resolution is a fixed distance, 102.6 µm, between the printhead nozzles and the Z-directional one is usually, 280 µm, twice the size of an average sand grain.A non-destructive and most representative permeability value can be obtained, using the computer simulation, on the reconstructed 3D X-ray tomography images obtained on a specific location of a 3D printed sand mould. This saves time and effort on printing a separate specimen for the traditional test which may not be the most representative to the printed mould.

Originality/value

The experimental result is compared with the computer simulated results.

Details

Rapid Prototyping Journal, vol. 25 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

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