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Process parameters in Fused Filament Fabrication (FFF) can affect mechanical and surface properties of printed parts. Numerous studies have reported parametric studies of various materials using full factorial and Taguchi design of experiments (DoEs). However, a comparison between the two are not well-established in literature. The purpose of this study is to compare full factorial and Taguchi DoEs to determine the effects of FFF process parameters on mechanical and surface properties of Nylon 6/66 copolymer. In addition, perform in-depth failure mechanism analysis to understand why the process parameters affect the responses.

A full factorial DoE was used to determine the effects of FFF process parameters, such as infill density, infill pattern, layer height and raster angle on responses, such as compressive strength, impact strength, surface roughness and manufacturing time of Nylon 6/66. Micro-computed tomography was used to analyse the impact test samples before and after impact and scanning electron microscope was used to understand the failure mechanism of infill and top layers. Differential scanning calorimetry (DSC) scans of infill and top layers were then taken to determine if a variation in crystallinity existed in different regions of the build.

Analysis of variance and main effects plots reveal that infill density has the greatest effect on mechanical and surface properties while manufacturing time is most affected by layer height for the polymer used. A 20% reduction in infill increased impact strength by 19% on average, X-ray images of some of the samples before and after impact tests are presented to understand the reason behind the difference. Moreover, DSC revealed a difference in the degree of crystallinity between the infill and top layers for 80% infill density samples. In addition, Taguchi DoE is realized to be a more efficient technique to determine optimum process parameters for responses that vary linearly as it reduces experimental effort significantly while providing mostly accurate results.

To the author’s knowledge, no published paper has reported a comparison between predictive DoE method with full factorial DoE to verify their accuracy in determining the effects of FFF process parameters on properties of printed parts. Also, a theory was developed based on DSC results that as the infill is printed faster, it cools slowly compared to the top layers, and hence the infill is in a less crystalline state when compared to the top layers. This increased the ductility of the infill (of 80% infill samples) and thus improved impact absorption.

Introduction: The notion of job losses during energy transition phases and their influences on fossil fuel economies have been debated in various aspects. Meanwhile, unemployment and poverty have been critical economic challenges for many developing countries, even the resource-rich countries in the Middle East. Concurrently, no country so far is poverty-free and has not entirely fulfilled Sustainable Development Goals (SDG) Nos. 1 and 8, as many resource-rich countries account for the significant global poverty and unemployment, such as Nigeria, Iraq, Yemen, and Venezuela.

Purpose: The issue of green transition has created new fears for the job market in the fossil fuel economies, where the lives of many people could be mainly affected. This study investigates the macroeconomic challenges of green transition and the macroeconomic consequences that fossil fuel economies will deal with.

Methodology: This study follows content analysis and a desk-search review of job loss during the green transition in the context of fossil fuel economies. In addition, the descriptive analysis is just a clear understanding of the fundamental review of the topic that will lead to another cross-country analysis study based on in-depth knowledge and analysing data.

Findings: The European Green Deal (EGD) will have profound economic, social, and political implications for fossil fuel-dependent economies for various reasons. First, fossil fuel economies are less diversified; the economy depends on a single commodity; the systems must be developed and people must prepare for a quick economic transition.

Introduction: Based on the given experiences, many government institutions failed in their strategic management and planning for managing COVID-19. Meanwhile, when a crisis disrupts a system, institutions lose their direction and fail to make necessary responses.

Purpose: The current study highlighted the impact of social justice and modern governance in providing equitable healthcare services and dealing with crises during the COVID-19 pandemic in developing countries.

Methodology: Cross-country analyses were used based on captured secondary data. We evaluated several indices, including, for example, Crisis Index Indicators, Worldometers, and the Global Health Security (GHS) Index 2019.

Findings: According to the GHS (2019) data, public health service delivery equity was ineffective, socially unjust, and unfair treatment was experienced in the context of the conflict-affected countries. Most conflict-affected countries (Iraq, Nigeria, Afghanistan, and Venezuela) did not have guidelines or public reports committing to providing prioritized healthcare services to the public and healthcare workers. The experience of conflict-affected countries has shown that healthcare disparities still exist. While many governments in conflict-affected countries failed to give equitable access to healthcare services during the COVID-19 pandemic to the public.