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Article
Publication date: 16 January 2017

Chad E. Duty, Vlastimil Kunc, Brett Compton, Brian Post, Donald Erdman, Rachel Smith, Randall Lind, Peter Lloyd and Lonnie Love

This paper aims to investigate the deposited structure and mechanical performance of printed materials obtained during initial development of the Big Area Additive Manufacturing…

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Abstract

Purpose

This paper aims to investigate the deposited structure and mechanical performance of printed materials obtained during initial development of the Big Area Additive Manufacturing (BAAM) system at Oak Ridge National Laboratory. Issues unique to large-scale polymer deposition are identified and presented to reduce the learning curve for the development of similar systems.

Design/methodology/approach

Although the BAAM’s individual extruded bead is 10-20× larger (∼9 mm) than the typical small-scale systems, the overall characteristics of the deposited material are very similar. This study relates the structure of BAAM materials to the material composition, deposition parameters and resulting mechanical performance.

Findings

Materials investigated during initial trials are suitable for stiffness-limited applications. The strength of printed materials can be significantly reduced by voids and imperfect fusion between layers. Deposited material was found to have voids between adjacent beads and micro-porosity within a given bead. Failure generally occurs at interfaces between adjacent beads and successive layers, indicating imperfect contact area and polymer fusion.

Practical implications

The incorporation of second-phase reinforcement in printed materials can significantly improve stiffness but can result in notable anisotropy that needs to be accounted for in the design of BAAM-printed structures.

Originality/value

This initial evaluation of BAAM-deposited structures and mechanical performance will guide the current research effort for improving interlaminar strength and process control.

Details

Rapid Prototyping Journal, vol. 23 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 December 2005

Daniel Jean, W. Jack Lackey and Chad E. Duty

To describe the thermal imaging control system used to deposit lines of graphite in a laser chemical vapor deposition (LCVD) system.

802

Abstract

Purpose

To describe the thermal imaging control system used to deposit lines of graphite in a laser chemical vapor deposition (LCVD) system.

Design/methodology/approach

A thermal imaging‐based control system is applied to the LCVD process to deposit layered carbon lines of uniform height and width. A 100 W CO2 laser focused to a 200 μm diameter spot size is used to provide the heat source for the carbon deposition. A high resolution thermal imaging camera is used to monitor and control the average deposition temperature.

Findings

Carbon lines are grown with heights of 250 μm and widths of 170 μm consisting of 20 layers. Laser spot temperatures are in excess of 2,170°C, and the total pressure used is 1 atm with a 75 percent methane concentration and the remainder hydrogen. The length of the lines is 3.3 mm, and the scan speed is 5 mm/min. The volumetric deposition rate is 0.648 mm3/h.

Research limitations/implications

The temperature process control resulted in uniform geometry at the center of the lines, but it was not as effective at the ends of the lines where the geometry was more complex.

Originality/value

Introduces a control technique for uniform line deposition for the LCVD process, which represents a core building block for complex geometries. The establishment of basic control algorithms will enable LCVD to realize the potential for rapid prototyping of metals and ceramics with sub‐millimeter feature sizes.

Details

Assembly Automation, vol. 25 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 18 January 2016

Wenchao Zhou, Frederick A List, Chad E Duty and Sudarsanam S Babu

The purpose of this paper is to explore the possibility of integrating inkjet printed circuitry with fused deposition modeling (FDM) structures to produce embedded electronics and…

2085

Abstract

Purpose

The purpose of this paper is to explore the possibility of integrating inkjet printed circuitry with fused deposition modeling (FDM) structures to produce embedded electronics and smart structures. Several of the challenges of combining these technologies are identified, and potential solutions are developed.

Design/methodology/approach

An experimental approach is taken to investigate some of the relevant physical processes for integrating FDM and inkjet deposition, including the printing, drying and sintering processes. Experimental data are collected to assist understanding of the problems, and engineering solutions are proposed and implemented based on the gained understanding of the problems.

Findings

Three challenges have been identified, including the discontinuity of the printed lines resulting from the irregular surface of the FDM substrate, the non-conductivity of the printed lines due to the particle segregation during the droplet drying process and the slow drying process caused by the “skinning effect”. Two engineering solutions are developed for the discontinuity problem. The non-conductivity issue and the slow drying process are attributed to the motion of the nanoparticles caused by the evaporation flow. The thermally activated drying process for the Cabot ink suggests that the proposed solution is effective. Timescale analysis and experimental data show that the printing conditions do not have a clear influence on the conductivity of the printed lines, and drying and sintering processes are more important.

Research limitations/implications

No quantitative model has yet been developed for simulating the printing, drying and sintering processes associated with inkjet printing on FDM substrates. Quantitative models can be extremely valuable for improvement in understanding the problems, optimizing the proposed solutions and coming up with better solutions.

Practical implications

The research findings in this work have great implications in implementing a hybrid FDM-inkjet deposition machine for fabricating embedded electronics and smart structures. All the proposed engineering solutions for the identified problems can be potentially integrated into one machine.

Social implications

The success of the integration of the FDM and inkjet deposition process will enable the design of compact electro-mechanical structures to replace the large heavy electro-mechanical systems.

Originality/value

This work represents one of the first attempts for integrating inkjet deposition of silver nanoparticle inks with the FDM process for making compact electro-mechanical structures. Three critical challenges are identified, and corresponding engineering solutions are proposed and implemented based on analysis of the relevant physical processes, including the printing, drying and sintering processes, which has laid the foundation for integrating the FDM and inkjet deposition processes.

Details

Rapid Prototyping Journal, vol. 22 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 3 August 2021

Elodie Paquet, Alain Bernard, Benoit Furet, Sébastien Garnier and Sébastien Le Loch

The purpose of this paper is to present a novel methodology to produce a large boat hull with a foam additive manufacturing (FAM) process. To respond to shipping market needs…

240

Abstract

Purpose

The purpose of this paper is to present a novel methodology to produce a large boat hull with a foam additive manufacturing (FAM) process. To respond to shipping market needs, this new process is being developed. FAM technology is a conventional three-dimensional (3D) printing process whereby layers are deposited onto a high-pressure head mounted on a six-axis robotic arm. Traditionally, molds and masters are made with computer numerical control (CNC) machining or finished by hand. Handcrafting the molds is obviously time-consuming and labor-intensive, but even CNC machining can be challenging for parts with complex geometries and tight deadlines.

Design/methodology/approach

The proposed FAM technology focuses on the masters and molds, that are directly produced by 3D printing. This paper describes an additive manufacturing technology through which the operator can create a large part and its tools using the capacities of this new FAM technology.

Findings

The study shows a comparison carried out between the traditional manufacturing process and the additive manufacturing process, which is illustrated through an industrial case of application in the manufacturing industry. This work details the application of FAM technology to fabricate a 2.5 m boat hull mold and the results show the time and cost savings of FAM in the fabrication of large molds.

Originality/value

Finally, the advantages and drawbacks of the FAM technology are then discussed and novel features such as monitoring system and control to improve the accuracy of partly printed are highlighted.

Details

Rapid Prototyping Journal, vol. 27 no. 8
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 7 January 2025

Christian Zamo Akono and Liliane Odette Medjo Obia

This study aims to examine the association between Not in Employment, Education, or Training (NEET) status and a set of individual and household socioeconomic factors, including…

8

Abstract

Purpose

This study aims to examine the association between Not in Employment, Education, or Training (NEET) status and a set of individual and household socioeconomic factors, including potential gender-based variations, for young people aged 15–34 years in Cameroon and Chad.

Design/methodology/approach

Using data from the 2021 Survey on Youths’ Transition to the Labour Market in Francophone Africa, logistic regressions were conducted to identify the determinants of NEET status, and the multivariate decomposition for nonlinear response models was employed to examine gender disparities in the likelihood of being NEET.

Findings

In Cameroon, the likelihood of being NEET is linked to factors such as age, being female, being in a couple, having dependent children, financial difficulties and urban residency. In Chad, NEET status is associated with higher education, age, being female, being in a couple and having dependent children, but decreases with secondary education, technical education and balancing work and study. Gender disparities in NEET status are largely explained by individual characteristics, accounting for 56.16% of the disparity in Cameroon and 73.72% in Chad. The main contributors in Cameroon are higher education, marital status and having children, while in Chad they are secondary and technical education, studying STEM, age, marital status and having children.

Originality/value

This paper makes two key contributions: first, it is the pioneering study on the determinants of entering the NEET category in sub-Saharan Africa, focusing on individual characteristics; second, it offers the first comprehensive decomposition of factors driving gender disparities in the likelihood of being NEET.

Details

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

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Book part
Publication date: 1 July 2024

Abdoulaye M. Hassane, Diana M. Madiyarova and Ousman N. Mahamat Nour

This chapter aims to analyze and evaluate the economic potential of Chad within the African continent, identify the challenges faced by the country, and propose potential…

Abstract

This chapter aims to analyze and evaluate the economic potential of Chad within the African continent, identify the challenges faced by the country, and propose potential solutions. The authors used a combination of qualitative and quantitative research methods. Relevant data is collected from reliable sources such as government reports, international organizations, research institutes, and academic studies, including data on Chad's GDP, trade flows, foreign direct investment (FDI), infrastructure, human capital, and natural resources.

The Republic of Chad is an agrarian country where the prosperity of 55% of the population depends on the development of agriculture, mainly livestock. Although rich in natural resources, Chad is one of the poorest countries in the world. Several investment projects have recently appeared in this country, which will help reduce the population's poverty in the future. The growth rate of Chad's economy lags behind that of the population. Foreign assistance is needed to solve the identified problem. With regard to the investment projects that have become more active this year, it would be unnecessary to be dizzy with success because they are still unable to break the established way of life. The Republic of Chad is situated in Africa and is considered one of the largest countries in the continent. The country has no access to the sea.

Details

Development of International Entrepreneurship Based on Corporate Accounting and Reporting According to IFRS
Type: Book
ISBN: 978-1-83797-669-0

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Article
Publication date: 5 December 2016

Nathan Kunz and Gerald Reiner

Foreign governments do not always welcome international humanitarian organizations responding to a disaster in their country. Many governments even impose restrictions on…

979

Abstract

Purpose

Foreign governments do not always welcome international humanitarian organizations responding to a disaster in their country. Many governments even impose restrictions on humanitarian supply chains through import barriers, travel restrictions or excessive bureaucracy. The purpose of this paper is to analyze these restrictions and try to identify the government characteristics that best explain the tendency to impose such restrictions.

Design/methodology/approach

Through a multiple case study among four international humanitarian organizations the authors identify and analyze the restrictions imposed on humanitarian supply chains in 143 different programs. The authors compare the average number of restrictions per country with different governmental and socio-economic situational factors.

Findings

The authors find that state fragility, a combination of government ineffectiveness and illegitimacy, is the characteristic that best explains the tendency of a government to impose restrictions on humanitarian supply chains.

Practical implications

Knowing that fragile states tend to impose a high number of restrictions helps humanitarian organizations to prepare adequately before entering a country with a fragile government. The organization can, for example, anticipate possible concerns and establish trust with the government. Commercial companies starting to do business in such country can learn from this knowledge.

Originality/value

Multiple studies have mentioned the strong impact of governments on humanitarian supply chains, but no paper has yet analyzed this problem in detail. The paper is the first to identify the characteristics that explain the number of restrictions governments impose on humanitarian supply chains, and what humanitarian organizations can do to address them.

Details

Journal of Humanitarian Logistics and Supply Chain Management, vol. 6 no. 3
Type: Research Article
ISSN: 2042-6747

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Article
Publication date: 1 March 2001

Duane Windsor

Corporate social responsibility is one of the earliest and key conceptions in the academic study of business and society relations. This article examines the future of corporate…

15679

Abstract

Corporate social responsibility is one of the earliest and key conceptions in the academic study of business and society relations. This article examines the future of corporate social responsibility. Bowen's (1953) key question concerned whether the interests of business and society merge in the long ran. That question is assessed in the present and future contexts. There seem to be distinctly anti‐responsibility trends in recent academic literature and managerial views concerning best practices. These trends raise significant doubts about the future status of corporate social responsibility theory and practice. The vital change is that a leitmotif of wealth creation progressively dominates the managerial conception of responsibility. The article provides a developmental history of the corporate social responsibility notion from the Progressive Era forward to the corporate social performance framework and Carroll's pyramid of corporate social responsibilities. There are three emerging alternatives or competitors to responsibility: (1) an economic conception of responsibility; (2) global corporate citizenship; and (3) stakeholder management practices. The article examines and assesses each alternative. The article then assesses the prospects for business responsibility in a global context. Two fundamentals of social responsibility remain: (1) the prevailing psychology of the manager; and (2) the normative framework for addressing how that psychology should be shaped. Implications for practice and scholarship are considered.

Details

The International Journal of Organizational Analysis, vol. 9 no. 3
Type: Research Article
ISSN: 1055-3185

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Book part
Publication date: 18 June 2020

Sourav Kumar Das, Kishor Naskar and Chandra Sekhar Sahu

Refugee can refer to movements of large groups of displaced people, who could be either internally displaced persons or other migrants. According to UN High Commissioner Report

Abstract

Refugee can refer to movements of large groups of displaced people, who could be either internally displaced persons or other migrants. According to UN High Commissioner Report for refugees (2017), 65.6 million people were forcibly displaced worldwide because of persecution, conflict, violence or human rights violation alone. Now we are witnessing a massive shift of humanity unlike any seen before. A huge population around the world, which is equivalent to the entire population of the UK, is displaced from their homes. More than 23 million of them are from five places: Syria, Afghanistan, South Sudan, the Lake Chad Basin and Somalia. And the astonishing figures are 11.5 million people in five years between 2011 and 2016 in Syria, 4 million displaced from 2013 in South Sudan, 3.8 million in Afghanistan, 2.3 million in Africa's Lake Chad basin and 1.6 million in Somalia. All of the above have the reasons either being unemployment, insecurity and political instability or civil war or droughtlike phenomena, all of which can be summarized as economic crisis. Most of the time, we do our research on the subject about the wake of the crisis, but nobody do the prefacing matter analysis. This chapter is mainly based on the secondary data of the World Bank and the UNHCR and various governments' official data. In this chapter, we are trying to identify the major parameters responsible for refugee generation and also we are analyzing the cause of these phenomena, whereas no research has been done yet about the era prefacing that crisis.

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Article
Publication date: 5 September 2016

Chad R. Lochmiller and Jennifer R Karnopp

– The purpose of this paper is to explore how school principals influenced or controlled leadership coaches working with assistant principals in urban secondary schools.

462

Abstract

Purpose

The purpose of this paper is to explore how school principals influenced or controlled leadership coaches working with assistant principals in urban secondary schools.

Design/methodology/approach

This longitudinal qualitative case study drew upon semi-structured interviews and program documents obtained from participants in a university-based leadership coaching program across three academic years. The study included 22 total participants, including ten assistant principals, nine leadership coaches, and three program staff.

Findings

A thematic analysis of the data produced three themes. First, principals controlled coaches’ work with assistant principals both directly and indirectly. Second, the extent of principal control influenced how coaches developed a confidential relationship with the assistant principals and what strategies they used to preserve the confidential nature of the coaching relationship. Third, the focus of the coaching support evolved in response to the assignment of responsibilities and duties to the assistant principals, which were largely outside the assistant principal and leadership coach’s control. The absence of alignment between coaching priorities and leadership responsibilities frustrated coaches.

Originality/value

The findings from this study make two significant empirical contributions to the literature. First, the study provides critical new insights about the extent to which politics generated by principals and administrative teams may influence the work of leadership coaches. Second, the study contributes to the sparse literature about leadership coaching for assistant principals, particularly those working in secondary school settings in the USA.

Details

International Journal of Mentoring and Coaching in Education, vol. 5 no. 3
Type: Research Article
ISSN: 2046-6854

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