1,721,047 research outputs found
Fabrication of porous soft magnets via laser powder bed fusion in-situ alloying
No full textToday, porous magnetic materials have been one of the focal points of studies in the field of treatment due to their absorbent properties. This study focuses on the production of porous magnetic FeSi6 alloy using laser powder bed fusion (LPBF) with in-situ alloying. Water atomized Fe and Si powders with high purity were used as the starting materials. Different hatch spacing and exposure time values were investigated to examine their impact on the porosity of the structure. Cylindrical specimens were produced, and their relative densities were measured. SEM analysis and magnetic property measurements were conducted to evaluate the resulting material. The study successfully achieved the production of high-porosity magnetic material, with some control over pore formation through the laser parameters. The magnetic properties of the material demonstrated results consistent with previous studies. Furthermore, the study found that in-situ alloying in the LPBF method yields magnetic properties comparable to those obtained using pre-alloyed powder, indicating the feasibility of this approach
Influence of laser speed and power on the magnetic properties of Fe-50 Wt% Ni Alloy manufactured by LPBF
No full textSoft magnetic materials are used in a wide range of devices, including mobile phones, computers, motors, and inductors. Among the soft magnets, the Fe-50 wt% Ni alloy exhibits superior properties such as high magnetic saturation and permeability with low coercivity, when manufactured by conventional methods such as injection moulding. However, until now, it is not clear if modern manufacturing methods such as those based on laser powder bed fusion can affect the magnetic response. This work aims to determine experimentally the influence of laser speed and power through additive manufacture and subsequent magnetic characterization of the manufactured samples. These measurements were compared with those of a commercial sample obtained via conventional fabrication methods. The results show that it is possible to achieve magnetic saturation similar to the commercial samples, with both values of ~1.7 T and acceptable permeability of 66 A·m−1 compared to the commercial ones 159 A·m−1 if samples were fabricated with 190 W laser power and 300 m·s−1 laser speed
Finite element analysis of the mechanical properties of laser powder bed fusion-produced Ti6Al4V sheet- and skeleton-gyroid structures
No full textTriply periodic minimal surface structures manufactured by additive manufacturing are one of the most important means to achieve lightweight in various fields. However, their manufacture using laser powder bed fusion still requires considerable research. In this study, three gyroid structures with volume fraction ranging from 10 to 30% were designed and fabricated using Ti6Al4V. Their mechanical properties, failure modes and energy absorption properties were studied by simulation prediction and experimental test. The results show that their elastic modulus, yield strength, peak stress and the energy absorption enhance with the increase in the volume fraction. The simulation results are in good agreement with the experimental results. Two failure modes appear on the adjacent side of the structure, namely 45-degree shear failure and layer-by-layer unit brittle collapse. In terms of energy absorption, the energy absorption efficiency of large volume fraction structure is more stable. This study significantly enhanced the understanding of gyroid structure and provided a more reliable basis for the selection of TPMS structure types and design parameters
Transforming e-waste into value: A circular economy approach to PCB recycling
No full textThis study delves into the pressing global issue of electronic waste (e-waste), with a specific emphasis on printed circuit boards (PCBs). PCBs, being a crucial component of electronic devices, contribute significantly to e-waste due to their intricate composition of hazardous substances and valuable metals such as gold, silver, and copper. The research explores the concept of the circular economy—an economic system aimed at eliminating waste through the continual use of resources—and its potential application in recycling PCBs. This involves a detailed investigation of the challenges and opportunities associated with various extraction methods and waste management strategies. The study also presents a case study on The Royal Mint’s innovative approach to gold extraction from PCBs. This practical example offers valuable insights into the application of circular economy principles in the context of PCB recycling, demonstrating how these principles can lead to improved resource efficiency, waste reduction, and economic benefits. The findings of this research underscore the need for further development and implementation of sustainable practices in e-waste management to mitigate environmental impact and capitalise on the economic potential of valuable materials in e-waste
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Calculating Domestic Environmental Impacts: Challenging and Solutions for an Interactive Configurator
No full textThe domestic consumptions are commonly claimed to be more than 60% of global GHG emissions and between 50 and 80% of total land, material and water use. In the last few years, a lot of methods and tools to estimate those impacts have been proposed in the literature and diffused on public administration portals (e.g. European Commissioner for the Environment) and on private Websites. However, an overall analysis of all the factors that contribute to the consumption of an entire home and the development of a support tool is still lacking. This paper discusses the main parameters to be considered for the analysis and the methods for calculating the environmental impacts, and it proposed a supported tool, in the form of an interactive configurator. It allows the user to enter the main data about her/his own home, the constituting components (e.g. appliances) and her/his habits and behaviours (i.e. ways of use), and then, after the processing, it provides the results, in terms of environmental impacts (kg of equivalent CO2) of the entire home and the constituting components, by also showing possible more sustainable alternatives
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Eco-Design for Metal Additive Manufacturing: A Parametric Model for Combining Mass Reduction with Recycled and Reused Powder
No full textEco-design for metal additive manufacturing (AM) can be pursued in different manners, including lightweight design and the reuse and recycling of powders. However, these options are contradictory due to the decline in characteris-tics in recycled and reused powders. This study proposes a parametric model of the environmental impact of AM process, including raw material extraction, metallur-gical process, scrap recycling, melting, atomization for the production of the powders and printing. The model consists of an objective function that has been derived from the Life Cycle Assessment (LCA) methodology applied to the AM process. Each contribution of the function has been parameterized, including decision variables about mass reduction and the percentage of use of recycled and reused powder. The eco-design for AM is pursued through the minimization of the objective function (i.e., the environmental impact of the process) by obtaining the most suitable values of the decision variables. The proposed model has been applied to an illustrative example related to the AM of a component made by Ti6Al4V
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