Shahrain Mahmood, A.J. Qureshi, Kheng Lim Goh and Didier Talamona
This paper aims to investigate the tensile strength of partially filled fused filament fabrication (FFF) printed parts with respect of cross-sectional geometry of partially filled…
Abstract
Purpose
This paper aims to investigate the tensile strength of partially filled fused filament fabrication (FFF) printed parts with respect of cross-sectional geometry of partially filled test pieces. It was reported in the authors’ earlier work that the ultimate tensile strength (UTS) is inversely proportional to the cross-sectional area of a specimen, whereas the number of shells and infill density are directly proportional to the UTS with all other parameters being held constant. Here, the authors present an in-depth evaluation of the phenomenon and a parametric model that can provide useful estimates of the UTS of the printed part by accounting for the dimensions of the solid floor/roof layers, shells and infills.
Design/methodology/approach
It was found that partially filled FFF printed parts consist of hollow sections. Because of these voids, the conventional method of determining the UTS via the gross cross-sectional area given by A = b × h, where b and h are the width and thickness of the printed part, respectively, cannot be used. A mathematical model of a more accurate representation of the cross-sectional area of a partially filled part was formulated. Additionally, the model was extended to predict the dimensions as well as the lateral distortion of the respective features within a printed part using input values from the experimental data.
Findings
The result from this investigation shows that to calculate the UTS of a partially filled FFF part, the calculation based on the conventional approach is not sufficient. A new meta-model is proposed which takes into account the geometry of the internal features to give an estimate of the strength of a partially filled printed part that is closer to the value of the strength of the material that is used for fabricating the part.
Originality/value
This paper investigates the tensile strength of a partially filled FFF printed part. The results have shown that the tensile strength of a partially filled part can be similar to that of a solid part, at a lower cost: shorter printing time and lower material usage. By taking into account the geometries within a printed part, the cross-sectional area can be accurately represented. The mathematical model which was developed would aid end-users to predict the tensile strength for a given set of input values of the process parameters.
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Shahrain Mahmood, A.J. Qureshi, Kheng Lim Goh and Didier Talamona
This paper aims to discuss the effect of changes of a comprehensive list of process parameters on part scalability and tensile strength of fused filament fabrication (FFF) printed…
Abstract
Purpose
This paper aims to discuss the effect of changes of a comprehensive list of process parameters on part scalability and tensile strength of fused filament fabrication (FFF) printed parts. A number of parameters hitherto not studied such as cross-sectional area and its interaction with number of shells and infill density are presented and studied.
Design/methodology/approach
From a preliminary investigation, results have shown that varying the process parameters affects the ultimate tensile strength (UTS) of a FFF printed component, with component scale and number of shells as the two most significant parameters affecting the UTS. A further investigation based on the interactions of four process parameters, specimen width, b, specimen thickness, h, number of shells, n, and infill density, i, and their effects on the UTS was performed. Taguchi’s design of experiment was used to develop an experimental plan in this investigation. Specimens were printed and tested for their tensile strength until fracture and the results analyzed.
Findings
Results obtained support an inverse relationship between part scalability, change in cross-sectional area and the UTS of a FFF printed part. The UTS results were calculated in line with conventional method based on the gross cross-sectional area of A = (b × h).
Originality/value
The paper investigates the effect of part scalability on the UTS of FFF printed parts and evaluates the conventional method of calculating material tensile strength of FFF printed parts using the gross cross-sectional area of A = (b × h). The results of this findings show that the conventional method cannot be used as FFF printed parts consists of partially filled parts and not a solid component.
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Recognising the significance of international trade in economic growth, this research explores the drivers of exports in South Asian Association for Regional Cooperation countries…
Abstract
Recognising the significance of international trade in economic growth, this research explores the drivers of exports in South Asian Association for Regional Cooperation countries from 2008 to 2021. The study employs the export demand model and the augmented exports supply model and utilises pooled time-series data. This study questions whether export supply decisions are based on traditional trade model factors, emerging trading realities or macroeconomic variables. The model based on fixed effects evaluates the connection between exports and their possible drivers. Traditional export supply models suggest determinants like production capacity, variable cost and relative pricing influencing South Asian export supply performance substantially. Changes in trade, for example, have a substantial impact on export supply, demonstrating that the trade liberalisation procedure promotes growth in exports, compression in imports and technological advancement. The worsening state of the energy industry and growing levels of corruption have proved to be significant deterrents to export supply decisions. The results verify foreign direct investment's positive and medium influence on the expansion of exports. Other variables, however, such as GDP and its growth, Official Development Assistance (ODA), development expenditure, indirect taxation, labour supply and the exchange rate of currencies, have a positive impact on the flow of exports. Furthermore, the data corroborate the notion that increased savings have a significant beneficial influence on the flow of exports. The study proposes that concerned governments examine their export policies and adopt new policies adapted in accordance with changing circumstances with the goal of increasing and enhancing the performance of exports.
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Abdel‐Aziz M. Mohamed, Mahmood A. Qureshi and Ali R. Behnezhad
The reliability of accounting internal control systems (AICS) is often viewed as a primary concern of auditors. Over the past three decades, several reliability models have been…
Abstract
The reliability of accounting internal control systems (AICS) is often viewed as a primary concern of auditors. Over the past three decades, several reliability models have been proposed for internal control. The main goal of these models is to provide an objective approach to evaluate the reliability of internal control systems. In addition, the models seek to assess the degree of audit reliance that can be placed on internal controls. This paper has a two‐fold objective: (1) to present an overview of the descriptive and prescriptive reliability models developed for the design and evaluation of internal control systems, and (2) to discuss the effects of various factors on the reliability assessment. Furthermore, two methods to estimate process reliabilities are presented and several numerical examples are provided to show the detailed calculations of the reliability and economic efficiency of accounting internal control systems.
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Elisa Aznarte Garcia, Ahmed Jawad Qureshi and Cagri Ayranci
This paper aims to present an investigation of material-process interaction of VAT-photopolymerization processes. The aim of the research is to evaluate the effect of different…
Abstract
Purpose
This paper aims to present an investigation of material-process interaction of VAT-photopolymerization processes. The aim of the research is to evaluate the effect of different printing factors on the tensile properties, such as elastic modulus, of 3D printed specimens.
Design/methodology/approach
To perform this study, Design of Experiments is used by the use of Taguchi’s techniques. The relationship between each factor and the elastic modulus, ultimate tensile stress and strain at break is obtained. Furthermore, the total print time is analyzed with respect to the obtained properties.
Findings
The study indicates that part orientation, exposure time to the UV light and layer thickness are the most important factors affecting the investigated properties. At the same time, it was found that the highest mechanical properties can be obtained with the shortest printing times. A comprehensive list of factors available on the slicing software and other factors, like the orientation of the part or its position, is investigated. Future studies including post curing and chemical characteristics based on the obtained results are necessary.
Originality/value
As a result of this research, it is outlined that using design for additive manufacturing for vat-photopolymerization, especially on DLP processes, 3D printing methods can be stablished. Furthermore, it outlines the possibility of tailoring mechanical properties of printed parts as a function of print parameters and print time. Considering the limited amount of information available in the open literature, the results presented in this paper are of great interest for researchers in the field of VAT-photopolymerization.
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PAKISTAN/IRAN: Border strife will not be eased quickly
Details
DOI: 10.1108/OXAN-ES243402
ISSN: 2633-304X
Keywords
Geographic
Topical
This study aims to define the concepts and determine the extent to which trade misinvoicing influences money laundering activities in developing countries.
Abstract
Purpose
This study aims to define the concepts and determine the extent to which trade misinvoicing influences money laundering activities in developing countries.
Design/methodology/approach
A qualitative research methodology was adopted using a descriptive synthesis of secondary data due to the heterogeneous nature of data sources (empirical evidence and content analysis).
Findings
Analysis revealed that in recent times trade misinvoicing accounts for over 20% of international trade value between developing and developed countries, and trade misinvoicing has been identified as a trade-based money laundering mechanism.
Research limitations/implications
Unavailability of homogenous data relating to trade misinvoicing among developing countries, different methods for measuring trade misinvoicing and inadequate high-quality research papers that led to the use of reports from reputable organisations.
Originality/value
To the best of the author’s knowledge, this study is among the few research works to assess the effects of trade misinvoicing and how it influences money laundering activities in developing countries.
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This paper provides, first, a historical perspective of accounting research relating to Asian/Pacific countries as seen from the vantage of the leading international journal in…
Abstract
This paper provides, first, a historical perspective of accounting research relating to Asian/Pacific countries as seen from the vantage of the leading international journal in the United States and, second, a bibliographical data base and index of twenty‐six years of articles on this region of the world. It accomplishes the first objective by presenting a tabular profile of research in international accounting as it pertains to countries in the Asian/Pacific Rim region as shown in articles published in the International Journal of Accounting (formerly, the International Journal of Accounting, Education and Research) and related publications which appeared from 1965 to 1990. The articles are classified according to country, research methodology, subject, and five‐year time periods. The paper accomplishes the second objective by providing an annotated bibliography of 125 articles on Asian/Pacific Rim countries and indices by country and methodology, and subject.
Swapnil Vyavahare, Soham Teraiya, Deepak Panghal and Shailendra Kumar
Fused deposition modelling (FDM) is the most economical additive manufacturing technique. The purpose of this paper is to describe a detailed review of this technique. Total 211…
Abstract
Purpose
Fused deposition modelling (FDM) is the most economical additive manufacturing technique. The purpose of this paper is to describe a detailed review of this technique. Total 211 research papers published during the past 26 years, that is, from the year 1994 to 2019 are critically reviewed. Based on the literature review, research gaps are identified and the scope for future work is discussed.
Design/methodology/approach
Literature review in the domain of FDM is categorized into five sections – (i) process parameter optimization, (ii) environmental factors affecting the quality of printed parts, (iii) post-production finishing techniques to improve quality of parts, (iv) numerical simulation of process and (iv) recent advances in FDM. Summary of major research work in FDM is presented in tabular form.
Findings
Based on literature review, research gaps are identified and scope of future work in FDM along with roadmap is discussed.
Research limitations/implications
In the present paper, literature related to chemical, electric and magnetic properties of FDM parts made up of various filament feedstock materials is not reviewed.
Originality/value
This is a comprehensive literature review in the domain of FDM focused on identifying the direction for future work to enhance the acceptability of FDM printed parts in industries.