| 1. |
- Santarius, T., et al.
(författare)
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Digitalization and Sustainability : A Call for a Digital Green Deal
- 2023
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Ingår i: Environmental Science and Policy. - : Elsevier BV. - 1462-9011 .- 1873-6416. ; 147, s. 11-14
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Tidskriftsartikel (refereegranskat)abstract
- The relation between digitalization and environmental sustainability is ambiguous. There is potential of various digital technologies to slow down the transgression of planetary boundaries. Yet resource and energy demand for digital hardware production and use of data-intensive applications is of substantial size. The world over, there is no comprehensive regulation that addresses opportunities and risks of digital technology for sustainability. In this perspective article, we call for a Digital Green Deal that includes strong, cross-sectoral green digitalization policies on all levels of governance. We argue that a Digital Green Deal should first and foremost aim at greater policy coherence: Current digital policy initiatives should include measures that service environmental goals, and environmental policies must address risks and advance opportunities of digital technologies to spur sustainability transformations.
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| 2. |
- Lauria, F., et al.
(författare)
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Ultra-processed foods consumption and diet quality of European children, adolescents and adults: Results from the I.Family study
- 2021
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Ingår i: Nutrition Metabolism and Cardiovascular Diseases. - : Elsevier BV. - 0939-4753. ; 31:11, s. 3031-3043
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Food processing has been indicated as a factor capable of negatively affecting the global food system, including the profile of consumers' diets. The objectives of the present study were to provide a description of the consumption of ultra-processed foods (UPFs) in the large population of children, adolescents and adults from eight European countries participating to the I.Family study, and to investigate the association between UPFs intake and nutritional quality of the diet. Methods and results: Dietary intake was assessed using a 24-h dietary recall. The quality of the diet was evaluated by the Healthy Dietary Adherence Score (HDAS) using an FFQ. UPFs were classified according to the NOVA classification. Almost half of the daily energy intake of the 7073 participants came from UPFs, and this trend decreased progressively with age. UPFs contributed more than 50 % of the daily intake of total and saturated fat, carbohydrates and about 70 % of sugars intake in children and adolescents. No differences in UPFs consumption were found according to the educational and socio-economic status of the population. Energy intake increased across the quintiles of UPFs intake, while HDAS decreased. The frequency of consumption of fruit and vegetable, fish, and fibre rich foods was low in the fifth quintile of UPFs intake, both in adolescents and in adults. The consumption of foods rich in calories and low in nutritional content, operationally defined as "junk food", was significantly higher in the fifth quintile. Conclusions: In the population of the European I.Family study, UPFs contributed a large proportion of the daily energy intake, especially in children and adolescents. Higher consumption of UPFs was associated with a lower quality of the diet. Registration number for clinical trials: ISRCTN62310987. 2021 The Italian Diabetes Society, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.
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| 4. |
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| 5. |
- Do, S., et al.
(författare)
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Associations Between Psychosocial Well-Being, Stressful Life Events and Emotion-Driven Impulsiveness in European Adolescents
- 2022
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Ingår i: Journal of Youth and Adolescence. - : Springer Science and Business Media LLC. - 0047-2891 .- 1573-6601. ; 51, s. 1106-1117
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Tidskriftsartikel (refereegranskat)abstract
- Knowing the extent to which mental well-being and stressful life events during adolescence contribute to personality characteristics related to risk-taking behaviors, such as emotion-driven impulsiveness, is highly relevant for the development of health promotion measures. This study examined whether psychosocial well-being and different stressful life events are associated with emotion-driven impulsiveness. In total, 3,031 adolescents (52% girls; M-age = 13.6 years) were included from the I. Family Study, a cross-sectional examination on lifestyle-related behaviors conducted across eight European countries in 2013/14. Linear mixed-effects regression models showed that higher psychosocial well-being was associated with lower emotion-driven impulsiveness independent of socio-demographic, health-related, and parental variables. A higher number of stressful life events was associated with higher emotion-driven impulsiveness. Psychosocial well-being and stressful life events need to be further considered in the development and tailoring of health promotion strategies that aim to reduce emotion-driven impulsiveness.
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| 6. |
- Hauser, Tobias, et al.
(författare)
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Acoustic emissions in directed energy deposition processes
- 2022
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 119:5-6, s. 3517-3532
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Tidskriftsartikel (refereegranskat)abstract
- Acoustic emissions in directed energy deposition processes such as wire arc additive manufacturing and directed energy deposition with laser beam/metal are investigated within this work, as many insights about the process can be gained from this. In both processes, experienced operators can hear whether a process is running stable or not. Therefore, different experiments for stable and unstable processes with common process anomalies were carried out, and the acoustic emissions as well as process camera images were captured. Thereby, it was found that stable processes show a consistent mean intensity in the acoustic emissions for both processes. For wire arc additive manufacturing, it was found that by the Mel spectrum, a specific spectrum adapted to human hearing, the occurrence of different process anomalies can be detected. The main acoustic source in wire arc additive manufacturing is the plasma expansion of the arc. The acoustic emissions and the occurring process anomalies are mainly correlating with the size of the arc because that is essentially the ionized volume leading to the air pressure which causes the acoustic emissions. For directed energy deposition with laser beam/metal, it was found that by the Mel spectrum, the occurrence of an unstable process can also be detected. The main acoustic emissions are created by the interaction between the powder and the laser beam because the powder particles create an air pressure through the expansion of the particles from the solid state to the liquid state when these particles are melted. These findings can be used to achieve an in situ quality assurance by an in-process analysis of the acoustic emissions.
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| 7. |
- Hauser, Tobias, et al.
(författare)
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Fluctuation effects in Wire Arc Additive Manufacturing of aluminium analysed by high-speed imaging
- 2020
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Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125 .- 2212-4616. ; 56:Part A, s. 1088-1098
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Tidskriftsartikel (refereegranskat)abstract
- Wire Arc Additive Manufacturing is a near-net-shape processing technology which allows the cost-effective manufacturing of big and customized metal parts. In the present work the Wire Arc Additive Manufacturing of AW4043/AlSi5(wt.%) with different lead angles of the welding torch was investigated. It has been shown that for some lead angles fluctuation effects occur in the structures produced if the interlayer temperature is either too low or too high. All experiments were analysed by high-speed imaging whereby the welding phenomena could be observed. In the case of Wire Arc Additive Manufacturing with a lead angle above 10° at lower interlayer temperatures, the deposited track consists out of several, seperated WAAM globules and is no longer in a uniform track. In the case of the dragging and neutral Wire Arc Additive Manufacturing processes at higher interlayer temperatures, fluctuation effects occur. In addition, by evaluating the high-speed videos with computer vision, it was found that such fluctuation effects can be detected at the arc frequency of the process. To avoid fluctuation effects caused by too low or too high interlayer temperatures, a pushing Wire Arc Additive Manufacturing process with a slightly tilted lead angle should be used.
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| 8. |
- Hauser, Tobias, et al.
(författare)
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Multi-Material Wire Arc Additive Manufacturing of low and high alloyed aluminium alloys with in-situ material analysis
- 2021
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Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 69, s. 378-390
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, the interest in the improved functionalisation of Additive Manufacturing components through multi-material solutions has increased because of the new possibilities in product design. In this work, an advanced Wire Arc Additive Manufacturing process for fabrication of multi-material structures of different aluminium alloys was investigated. Mechanical properties such as tensile strength, yield strength, fracture elongation, and hardness were analysed for multi-material parts and compared with the mechanical properties of mono-material parts. It was found that the strength of multi-material components was limited by the properties of the individual aluminium alloys and not by those of the material transition zones. Microsections and EDX line scans revealed a smooth transition zone without any significant defects. Furthermore, process monitoring approaches for quality assurance of the correct material composition in such multi-material structures were investigated. Different sensor data were captured during multi-material Wire Arc Additive Manufacturing to identify and observe various characteristics of the process. It was shown that the voltage, current, acoustic, and spectral emission data can be used for in-situ monitoring to detect the chemical differences between the two aluminium alloys 6060 and 5087. Characteristic patterns in the frequency range were found, which can be attributed to a frequency shift that occurred due to the different material properties. Spectral analysis revealed changes in the ratios of green and blue light emission to red light emission, which was also due to the different magnesium contents.
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| 9. |
- Hauser, Tobias, et al.
(författare)
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Oxidation in wire arc additive manufacturing of aluminium alloys
- 2021
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Ingår i: Additive Manufacturing. - : Elsevier. - 2214-8604 .- 2214-7810. ; 41
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Tidskriftsartikel (refereegranskat)abstract
- Wire Arc Additive Manufacturing is a near-net-shape machining technology that enables low-cost production of large and customised metal parts. In the present work, oxidation effects in Wire Arc Additive Manufacturing of the aluminium alloy AW4043/AlSi5(wt%) were investigated. Two main oxidation effects, the surface oxidation on aluminium parts and the oxidation anomalies in aluminium parts were observed and analysed. The surface oxidation on aluminium parts changed its colour during Wire Arc Additive Manufacturing from transparent to white. In the present work, it was shown by high-speed imaging that this change in the surface oxidation took place in the process zone, which was covered by inert gas. Since the white surface oxidation formed in an inert gas atmosphere, it was found that the arc interacts with the existing amorphous oxide layer of the previously deposited layer and turns it into a white duplex (crystalline and amorphous) oxide layer. In addition to the analysis of the white surface oxidation, oxidation anomalies, which occur at low shielding from the environment, were investigated. It was shown by physical experiments and Computational Fluid Dynamics simulations, that these oxidation anomalies occur at inadequate gas flow rates, too big nozzle-to-work distances, process modes with too high heat input, or too high wire feed rates. Finally, a monitoring method based on light emission spectroscopy was used to detect oxidation anomalies as they create peaks in the spectral emission when they occur.
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| 10. |
- Hauser, Tobias, et al.
(författare)
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Porosity in wire arc additive manufacturing of aluminium alloys
- 2021
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Ingår i: Additive Manufacturing. - : Elsevier. - 2214-8604 .- 2214-7810. ; 41
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Tidskriftsartikel (refereegranskat)abstract
- Wire Arc Additive Manufacturing is a near-net-shape processing technology which allows cost-effective manufacturing of large and customized metal parts. Processing of aluminium in Wire Arc Additive Manufacturing is quite challenging, especially in terms of porosity. In the present work, pore behaviour in Wire Arc Additive Manufacturing of AW4043/AlSi5(wt%) was investigated and a post-process monitoring approach was developed. It has been observed that as the shielding gas flow rate increases, the porosity in aluminium parts also increases due to the rapid solidification of the melt pool by forced convection. The higher convection rate seems to limit the escape of gas inclusions. Furthermore, gas inclusions escaping from the melt pool leave cavities on the surface of each deposited layer. Process camera imaging is used to monitor these cavities to acquire information about the porosity in the part. The observations were supported by Computational Fluid Dynamics simulations which show that the gas flow rate correlates with the porosity in aluminium parts manufactured by Wire Arc Additive Manufacturing. Since a lower gas flow rate leads to reduced convective cooling, the melt pool remains liquid for a longer period allowing pores to escape for a longer period and thus reducing porosity. Based on these investigations, a monitoring approach is presented.
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