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1 – 10 of 73
Book part
Publication date: 12 July 2021

Mohd Fadhli Abd Rashid, Noraliani Alias, Kamarudin Ahmad, Radzuan Sa’ari, Frank Tsung-Chen Tsai, Mohd Zamri Ramli and Zulkiflee Ibrahim

The impact of climate change towards water surface resources is crucial, particularly in developing and non-developing countries. Groundwater as a main water resource is thus an…

Abstract

The impact of climate change towards water surface resources is crucial, particularly in developing and non-developing countries. Groundwater as a main water resource is thus an essential. However, contamination due to hydrocarbon spills affects the groundwater as a water resource, especially as a main source of drinking water. This chapter investigates the light non-aqueous phase liquid (LNAPL) penetrations in double-porosity soil with different moisture contents and with or without vibration impact. It also explains the LNAPL penetration phenomena by employing image analysis. The physical laboratory experiments were implemented using an acrylic cylinder, a mirror, toluene and a Nikon D90 DSLR digital camera. Prepared soil was poured in an acrylic cylinder and compressed with compressor until it became 10 cm in height. LNAPL was then poured instantaneously onto the acrylic cylinder that was filled with soil sample. The LNAPL penetration patterns were recorded and monitored using a Nikon D90 DSLR digital camera. The processing technique was conducted at predetermined time intervals using Surfer software and Matlab routine to plot the LNAPL pattern. The results showed that a higher penetration rate of LNAPL occurred with higher moisture content and without vibration impact. The penetration time for LNAPL to reach the bottom of the soil sample was found to be longer for the soil that had low moisture content and with vibration impact.

Details

Water Management and Sustainability in Asia
Type: Book
ISBN: 978-1-80071-114-3

Keywords

Article
Publication date: 9 June 2023

Asif Ur Rehman, Burak Karakas, Muhammad Arif Mahmood, Berkan Başaran, Rashid Ur Rehman, Mertcan Kirac, Marwan Khraisheh, Metin Uymaz Salamci and Rahmi Ünal

For metal additive manufacturing, metallic powders are usually produced by vacuum induction gas atomization (VIGA) through the breakup of liquid metal into tiny droplets by gas…

Abstract

Purpose

For metal additive manufacturing, metallic powders are usually produced by vacuum induction gas atomization (VIGA) through the breakup of liquid metal into tiny droplets by gas jets. VIGA is considered a cost-effective technique to prepare feedstock. In VIGA, the quality and the morphology of the produced particles are mainly controlled by the gas pressure used during powder production, keeping the setup configuration constant.

Design/methodology/approach

In VIGA process for metallic additive manufacturing feedstock preparation, the quality and morphology of the powder particles are mainly controlled by the gas pressure used during powder production.

Findings

In this study, Inconel-625 feedstock was produced using a supersonic nozzle in a close-coupled gas atomization apparatus. Powder size distribution (PSD) was studied by varying the gas pressure.

Originality/value

The nonmonotonic but deterministic relationships were observed between gas pressure and PSD. It was found that the maximum 15–45 µm percentage PSD, equivalent to 84%, was achieved at 29 bar Argon gas pressure, which is suitable for the LPBF process. Following on, the produced powder particles were used to print tensile test specimens via LPBF along XY- and ZX-orientations by using laser power = 475 W, laser scanning speed = 800 mm/s, powder layer thickness = 50 µm and hatch distance = 100 µm. The yield and tensile strengths were 9.45% and 13% higher than the ZX direction, while the samples printed in ZX direction resulted in 26.79% more elongation compared to XY-orientation.

Details

Rapid Prototyping Journal, vol. 29 no. 9
Type: Research Article
ISSN: 1355-2546

Keywords

Book part
Publication date: 30 December 2004

Shigeru Asaba and Hideki Yamawaki

This study examines the determinants of performance of foreign manufacturing subsidiaries in Japan. The study finds that a foreign parent’s size, the subsidiary’s age, and a…

Abstract

This study examines the determinants of performance of foreign manufacturing subsidiaries in Japan. The study finds that a foreign parent’s size, the subsidiary’s age, and a complicated distribution system influence a subsidiary’s performance. There was little significant change in these determinants over a 20-year period. However, for subsidiaries that survived over the observation period of this study, some determinants changed. We also found that by forming joint ventures with Japanese firms, foreign firms can overcome the obstacle of distribution and circumvent the disadvantage of inexperience. Moreover, the mitigating effects of joint ventures vary, depending on the type of Japanese partner.

Details

Japanese Firms in Transition: Responding to the Globalization Challenge
Type: Book
ISBN: 978-0-76231-157-6

Article
Publication date: 1 January 2001

Chaoshin Chiao, Ken Hung and Gladson I. Nwanna

The purpose of this paper is to investigate the impact of market liberalization programs on firms' exchange‐rate exposure. We consider, in particular, the effects of the timing of…

Abstract

The purpose of this paper is to investigate the impact of market liberalization programs on firms' exchange‐rate exposure. We consider, in particular, the effects of the timing of the three liberalization events through which the government of Taiwan carried out explicit policies to gradually open its foreign exchange and stock markets. Although we cannot corroborate that most exporting firms are individually exposed to exchange‐rate risk, we cannot, however, reject that the exporting firms are jointly exposed to exchange‐rate risk in all sub‐periods. Furthermore, we find that Taiwanese exporting firms are greatly affected by timing of the three liberalization events.

Details

Competitiveness Review: An International Business Journal, vol. 11 no. 1
Type: Research Article
ISSN: 1059-5422

Article
Publication date: 13 January 2012

M. Averyanova, E. Cicala, Ph. Bertrand and Dominique Grevey

The purpose of this paper is to investigate the effect of main process parameters of selective laser melting (SLM) technology on single lines and single layers manufactured from…

2287

Abstract

Purpose

The purpose of this paper is to investigate the effect of main process parameters of selective laser melting (SLM) technology on single lines and single layers manufactured from 17‐4 PH martensitic powder using the experimental design approach.

Design/methodology/approach

A fractional factorial approach has been applied to vary and to identify the optimal set of process parameters using three different powder particle size distributions for 17‐4 PH steel. This paper assesses the impact of influence factors such as process and material parameters on objective factors such as dimension of single lines and single layers, as well as surface roughness.

Findings

The influence of process parameters and materials properties on single line and single layer manufacture is shown and proved statistically. The effect of each process parameter and their interactions on single layer and single line stability and quality has been investigated, and a complex objective function analyzing geometrical stability of single lines has been proposed. The findings indicate the most appropriate 17‐4 PH powder particle size distribution.

Originality/value

The research provides a systematic scientific approach using fractional factorial experiment design to identify the influence of process parameters, materials parameters and their combinations on essential martensitic steels (17‐4 PH steel) single lines and single layers characteristics such as geometrical stability and surface roughness. This approach will be extended to 3D parts fabrication and reported in a later paper.

Details

Rapid Prototyping Journal, vol. 18 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 26 August 2021

Hong-Chuong Tran, Yu-Lung Lo, Trong-Nhan Le, Alan Kin-Tak Lau and Hong-You Lin

Depending on an experimental approach to find optimal parameters for producing fully dense (relative density > 99%) Inconel 718 (IN718) components in the selective laser melting…

Abstract

Purpose

Depending on an experimental approach to find optimal parameters for producing fully dense (relative density > 99%) Inconel 718 (IN718) components in the selective laser melting (SLM) process is expensive and offers no guarantee of success. Accordingly, this study aims to propose a multi-scale simulation framework to guide the choice of processing parameters in a more pragmatic manner.

Design/methodology/approach

In the proposed approach, a powder layer, ray tracing and heat transfer simulation models are used to calculate the melt pool dimensions and evaporation volume corresponding to a small number of laser power and scanning speed conditions within the input design space. A layer-heating model is then used to determine the inter-layer idle time required to maximize the temperature convergence rate of the solidified layer beneath the power bed. The simulation results are used to train surrogate models to construct SLM process maps for 3,600 pairs of the laser power and scanning speed within the input design space given three different values of the underlying solidified layer temperature (i.e., 353 K, 673 K and 873 K). The ideal selection of laser power and scanning speed of each process map is chosen based on four quality-related criteria listed as follows: without the appearance of key-hole melting; an evaporation volume less than the volume of the d90 powder particles; ensuring the stability of single scan tracks; and avoiding a weak contact between the melt pool and substrate. Finally, the optimal laser power and scanning speed parameters for the SLM process are determined by superimposing the optimal regions of the individual process maps.

Findings

The feasibility of the proposed approach is demonstrated by fabricating IN718 test specimens using the optimal processing conditions identified by the simulation framework. It is shown that the maximum density of the fabricated parts is 99.94%, while the average density is 99.88% and the standard deviation is less than 0.05%.

Originality/value

The present study proposed a multi-scale simulation model which can efficiently predict the optimal processing conditions for producing fully dense components in the SLM process. If the geometry of the three-dimensional printed part is changed or the machine and powder material is altered, users can use the proposed method for predicting the processing conditions that can produce the high-density part.

Article
Publication date: 9 September 2013

Fevzi Karsli and Mustafa Dihkan

The purpose of this paper is to provide crystal size distribution (CSD) using photogrammetric and image analysis techniques. A new algorithm is proposed to detect CSDs and a…

Abstract

Purpose

The purpose of this paper is to provide crystal size distribution (CSD) using photogrammetric and image analysis techniques. A new algorithm is proposed to detect CSDs and a comparison is carried out with conventional watershed segmentation algorithm.

Design/methodology/approach

Polished granite plates were prepared to designate the metrics of CSD measurements. There are many important metrics for measurements on CSD. Some of them are orientation, size, position, area, aspect ratio, convexity, circularity, perimeter, convex hull, bounding box, eccentricity, shape, max-min length of CSD's fitted and corrected ellipse, and population density in a per unit area. Prior to image processing stage, camera calibration was performed to remove the image distortion errors. Image processing techniques were applied to corrected images for detecting the CSD parameters.

Findings

The proposed algorithm showed the improved preservation of size and shape characteristics of the crystal material when compared to the watershed segmentation. According to the experimental results, proposed algorithm revealed promising results in identifying CSDs more easily and efficiently.

Originality/value

This paper describes CSD of granitic rocks by using automated grain boundary detection methods in polished plate images. Some metrics of CSDs were detected by employing a new procedure. A computer-based image analysis technique was developed to measure the CSDs on the granitic rock plates. A validation is done by superimposing digitally detected CSD metrics to original samples.

Details

Sensor Review, vol. 33 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 June 2004

Afaf Abdul Jabbar Saed

The purpose of this study is to estimate the long‐run elasticities of the demand (consumption) for total energy in Jordan for the 1980‐1999 period. Assuming a simple linear…

Abstract

The purpose of this study is to estimate the long‐run elasticities of the demand (consumption) for total energy in Jordan for the 1980‐1999 period. Assuming a simple linear relationship, in order to estimates the elasticities of a simple long‐run demand equation, we then employ a procedure just recently prescribed by Stock‐Watson (1993) known as Dynamic OLS (DOLS). The DOLS procedure allows for co‐integrated variables as well as tackling the problem of simultaneity amongst the regressors. Furthermore, Stock and Watson showed that DOLS is more favorable, particularly in small size samples, compared to a number of alternative estimators of longrun parameters, including those proposed by Engle‐Granger (1987), Johansen (1988) and error correction model. The analysis provided in this paper showed that the income elasticity of final energy consumption is 1.15, which indicated that the economic growth is accompanied by proportional increase in energy consumption. The responsiveness of energy consumption to price change is ‐1.14 suggesting that taxes on their own are likely to achieve government goals for energy conservation.

Details

Journal of Economic and Administrative Sciences, vol. 20 no. 1
Type: Research Article
ISSN: 2054-6238

Keywords

Article
Publication date: 30 September 2014

José María Arranz and Carlos García-Serrano

The purpose of this paper is to examine the wage distribution in Spain, its evolution in recent years and the implications for increased wage dispersion. Accordingly, its…

Abstract

Purpose

The purpose of this paper is to examine the wage distribution in Spain, its evolution in recent years and the implications for increased wage dispersion. Accordingly, its attention focuses on the following issues: first, the paper investigates how personal, job and firm attributes affect the wages distribution and examine earnings differentials between and within groups of workers according to their individual and job characteristics throughout the conditional wage distribution; and second, the paper analyses whether the business cycle may influence the magnitude of these differentials.

Design/methodology/approach

Using administrative data from the Spanish Social Security and the Tax Administration National Agency, the paper estimates OLS and quantile regression (QR) models in order to assess the impact of personal, job and workplace attributes on between- and within-groups wage inequality.

Findings

Among other things, we find that, although the average wage has been increasing over time (until 2009), changes have not been uniform across the earnings distribution, making the dispersion fall during boom years but rise during downturn years. Furthermore, changes in the impacts of some characteristics (types of contract, education/qualifications, region and employer size) contributed to higher wage dispersion, while others (tenure) made the distribution more equal.

Originality/value

The analysis of the paper in novel in that it investigates whether wage differentials respond to the business cycle and what the source of that variation is. Moreover, it analyses wages differentials not only at the mean but also throughout the conditional earnings distribution, making it possible to assess the impact of these attributes on between- and within-groups wage inequality.

Details

International Journal of Manpower, vol. 35 no. 7
Type: Research Article
ISSN: 0143-7720

Keywords

Article
Publication date: 10 May 2021

Rhys J. Williams, Luke Fox and Candice Majewski

This study aims to demonstrate for the first time that the cheap, commodity polymer, poly(propylene), can be successfully processed using high speed sintering, and that it can be…

Abstract

Purpose

This study aims to demonstrate for the first time that the cheap, commodity polymer, poly(propylene), can be successfully processed using high speed sintering, and that it can be recycled several times through the process, with little to no detriment to either the polymer itself or the parts obtained. This is significant as a step towards the realisation of high speed sintering as a technology for high-volume manufacturing.

Design/methodology/approach

A poly(propylene) powder designed for laser sintering was used to build parts on a high speed sintering machine. The unsintered powder was then collected and reused. Repeating this process allowed creation of seven generations of aged powder. A variety of characterisation techniques were then used to measure polymer, powder and part properties for each generation to discern any effects arising from ageing in the machine.

Findings

It was found that poly(propylene) could be used successfully in high speed sintering, albeit with a low build success rate. Increased powder age was found to correlate to an increase in the build success rate, changes in microscopic and bulk powder properties and improvement to the dimensional accuracy of the parts obtained. By contrast, no discernible correlations were seen between powder age and polymer molecular weight, or between powder age and the tensile properties of parts.

Originality/value

This is the first report of the use of poly(propylene) in high speed sintering. It is also first study regarding powder recyclability in high speed sintering, both in general and using poly(propylene) specifically.

Details

Rapid Prototyping Journal, vol. 27 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

1 – 10 of 73