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- Aluminum-to-Steel Cladding by Explosive WeldingPublication . Carvalho, Gustavo H. S. F. L.; Galvão, Ivan; Mendes, Ricardo; Leal, Rui M.; Loureiro, AltinoThe production of aluminum-carbon steel and aluminum-stainless steel clads is challenging, and explosive welding is one of the most suitable processes to achieve them. The present work aims to investigate the coupled effect of two strategies for optimizing the production of these clads by explosive welding: the use of a low-density interlayer and the use of a low-density and low-detonation velocity explosive mixture. A broad range of techniques was used to characterize the microstructural and the mechanical properties of the welds, specifically, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, microhardness and tensile-shear testing with digital image correlation analysis. Although aluminum-carbon steel and aluminum-stainless steel have different weldabilities, clads with sound microstructure and good mechanical behavior were achieved for both combinations. These results were associated with the low values of collision point and impact velocities provided by the tested explosive mixture, which made the weldability difference between these combinations less significant. The successful testing of this explosive mixture indicates that it is suitable to be used for welding very thin flyers and/or dissimilar materials that easily form intermetallic phases.
- Are you ready for the challenge? Social Media Health Challenges for Behaviour ChangePublication . Saboia, Inga; Almeida, Ana Margarida Pisco; Sousa, Pedro; Pernencar, CláudiaChallenges are one of the most common strategies used by Opinion Leaders on Social Media to engage users. They are often found in different areas; in the Health field, the use of challenges is growing, namely through initiatives aiming at eating behaviour change. Instagram is considered to be one of the most used Social Media applications to develop these initiatives, allowing Opinion Leaders to communicate and engage with their online followers. Despite this scenario, little is known regarding how Health Challenges are being used and what is their impact on behaviour change. Previous research has already shown how Opinion Leaders use Instagram to promote eating behaviour change. The purpose of this paper is to conceptualize, describe and discuss Social Media Health Challenges, aiming to analyse Instagram challenges on healthy eating. The study was organized in two phases: the first one is a literature review based on Prisma method that supported the conceptualisation of SocialMedia Challenges and the design for the second phase where Social Media Health Challenges of Opinion Leaders, such as Nutritionists, Health Lifestylers and Patient Opinion Leaders (POLS) were analysed. Results showed that most of the challenges are promoted by Patient Opinion Leaders and Health Lifestylers. Followers adhere to Social Media Health Challenges related to weight loss, engaging with Opinion Leaders. The psychological-cognitive components (such as habits, motivation, and self-control) were found in the analysed challenges, and Instagram is one of the used tools to promote these Initiatives. These results point to new paths regarding future research on other behaviour change online initiatives.
- Ceramic products and their chromatic ‘DNA’ markersPublication . Lobo, CarlaOriginally produced with local raw materials and manufactured by ancestral processes, ceramic products have always been the result of knowledge transmitted from generation to generation. These artefacts reflect and reinterpret traditional, individual and collective formal vocabularies, integrating fragments of the day-to-day life of the local society, which conferred a geographical and sociocultural singularity revealing their local, regional, and national identities. From intrinsic to extrinsic characteristics, from raw materials to formal language, it is possible to find a plethora of combinatorial markers that characterize and differentiate these ceramic products – in other words, their ‘DNA’. Among such DNA markers, colour has been a geographical and cultural ‘locator’ par excellence of ceramic products: either by the colouration of raw materials, or inks or glazes, or by adopted colour schemes, which reflect not only the local availability of pigments and oxides, but also local preferences and culture. Furthermore, the characteristics of firing, an alchemical process, revealing a myriad of chromatic solutions based on acquired and arcane knowledge, confer a unique character to such ceramic products. The present globalization era has given way to the emergence of ‘transgenic’ ceramics, uprooted from their origins. Despite the resurgence of the appreciation of local knowledge and traditions as a reaction to this scenario, can we still identify clear references to their origin – ceramic chromatic DNA markers – even if these artefacts are the result of this ‘transgenic mutation’? The study substantiates that colour, as a DNA marker of ceramic products still exists, and is associated to cultural identity.
- Drawing powersPublication . Poeiras, Fernando
- Explosive welding of aluminium to stainless steel using carbon steel and niobium interlayersPublication . Carvalho, G.H.S.F.L.; Galvão, I.; Mendes, R.; Leal, R. M.; Loureiro, A.This work aimed to study aluminium to stainless steel explosive welds produced using two different interlayers: carbon steel and niobium. The use of each interlayer was analysed and compared microstructurally and mechanically using many characterisation techniques. The final joints using both interlayers presented favourable interfacial microstructure: waves on both interfaces. However, the joint using the carbon steel interlayer showed the best mechanical properties compared to the joints using the niobium interlayer. All interfaces found on both welds were wavy. However, depending on the metallic alloy combination, the shape of the wave is completely different. The results suggest that the shape of the waves is influenced by the shock impedance mismatch of the materials being welded. The impedance mismatch parameter (IMP) developed for explosive welding in this work proved to be a compelling method to order metallic combinations in a single axis to estimate the tendency to form typical or curled waves. Typical symmetrical waves tend to develop less quantity of IMCs than curled waves. However, the mechanical tests performed did not detect differences that could have been caused by this difference.
- The Fourth “R” - The Reversion of Objects as a Way of Reducing WastePublication . S. GonçalvesGiven the evident inefficiency of the policies and mechanisms established to deal with environmental degradation, it is essential to understand the reasons for their failures and to try alternative ways to mitigate the environmental problems associated with the replacement of objects. The ideas behind the so-called “3 R’s” policy, born of a sequence of two defining moments in the definition of environmental policies in Europe, - Agenda XXI in 1992 [1] and the 5th European Environment and Development Program of 1993 - have produced encouraging results since their creation, but failed to halt the increasing degradation of the environment on a planetary level. One of the problems derives from the fact that any of r's is strongly dependent on the environmental conscience, or even ethics, of the citizens responsible for the decisions regarding the products in their different moments of existence - from their design and production to their use and subsequent destination. This dependence leads to a high fallibility of environmental policies, insofar as western society suggests, in the way it behaves, a direction opposite to that which they advocate. It is thus important to reflect on ways of designing and producing things whose environmental performance is less dependent on the environmental consciousness of the end user, so that this awareness is not so decisive in the impact resulting from the disposal of objects. The present work tries to analyse the response of a group of students of design to the introduction of a “4thR”, that we call Reversion, and that is to think products of daily use whose form is conditioned by the necessity of its components can be, when dismantled of the system, seen as raw material directly usable for another purpose, easily determined by the user, and not as a technical component of an obsolete system. Functional prototypes will be realized in order to evaluate and validate the products regarding their effective performance in terms of production and use, as well as the possibility of reuse of their components in contexts other than those for which the objects were designed.
- A INDUSTRIA CERÂMICA DA LOUÇA UTILITÁRIA E DECORATIVA NA PERSPECTIVA DAS ESTRATÉGIAS DO LANÇAMENTO DE NOVOS PRODUTOS DE ECO-DESIGNPublication . Frade, José Manuel Couceiro Barosa Correia; Ferroli, Paulo Cesar MachadoEste artigo pretende evidenciar estratégias de eco-design e de sustentabilidade que são aplicadas no processo de design de novos produtos em empresas dos subsetores industriais da cerâmica utilitária e decorativa em portugal. A divulgação deste trabalho pretende servir como fonte de inspiração ao design de futuros produtos que se diferenciem por serem ambientalmente adequados, economicamente viáveis e socialmente responsáveis, fatores que são cada vez mais importantes nos critérios de decisão dos consumidores nomeadamente dos mercados internacionais mais exigentes e evoluídos onde as empresas portuguesas comercializam os seus produtos.
- Influence of Tool Geometry and Process Parameters on Torque, Temperature, and Quality of Friction Stir Welds in Dissimilar Al AlloysPublication . Manuel, Neves; Beltrão, Daniel; Galvão, Ivan; Leal, Rui M.; Costa, José D.; Loureiro, AltinoIn the current investigation, the influence of the tool geometry, the position of the materials in the joint, the welding speed on the temperature and torque developed, and on the quality of the welds in dissimilar and tri-dissimilar T joints were analysed. The aluminium alloys used were AA2017-T4, AA6082-T6, and AA5083-H111 and the friction stir welds were performed with identical shoulder tools, but with either a pin with simple geometry or a pin with progressive geometry. Progressive pin tools proved to be a viable alternative in the production of dissimilar and tri-dissimilar welds, as they provide a larger tool/material friction area and a larger volume of dragged material, which promotes an increase in the heat generated and a good mixing of the materials in the stir zone, although they require a higher torque. Placing a stronger material on the advancing side also results in a higher temperature in the stir zone but requires higher torque too. The combination of these factors showed that tools with a progressive pin provide sound dissimilar and tri-dissimilar welds, unlike single-pin tools. The increase in the welding speed causes the formation of defects in the stir zone, even in tri-dissimilar welds carried out with a tool with a progressive pin, which impairs the fatigue strength of the welds.
- Low-profile, extremely wideband, dual-band-notched MIMO antenna for UWB applicationsPublication . Bhattacharya, Ankan; Roy, Bappadittya; Caldeirinha, Rafael F. S.; Bhattacharjee, Anup K.In this article, an extremely wideband, isolation-enhanced, low-profile “Multiple-Input-Multiple-Output” (MIMO) antenna along with dual-band-notched features has been investigated. The antenna proposed herein, possesses two mutually orthogonal staircase-etched radiators for achieving a wide bandwidth. The radiating elements are placed mutually perpendicular in order to achieve polarization diversity and high isolation, i.e. for minimization of mutual coupling effect between adjacent radiating elements. The antenna exhibits an extremely wide frequency bandwidth covering 1.2–19.4 GHz except two frequency band notches centered at 3.5 and 5.5 GHz, respectively, originated due to the incorporation of a “Rectangular Complementary Split Ring Resonator (RCSRR)” structure and by etching dual “L-shaped” slits in the ground plane. The center frequency of the notched bands is adjusted by fine tuning of the dimensions of the incorporated band-notching structures. Isolation level (S21) better than −20 dB has been obtained due to the insertion of a “T-shaped” parasitic element as a decoupling structure. A prototype of the proposed antenna having dimension of 20 mm × 20 mm (0.08 λo × 0.08 λo) is fabricated and the antenna responses have been measured. Obtained results show that the miniaturized MIMO diversity antenna is undoubtedly a capable contender for communications supporting an extremely wide impedance bandwidth along with band-notched features for WLAN and WiMAX.
- Quarry Sonnets: Artistic Methodologies in More-than-Human ReasoningPublication . Santos, MiguelThe article proposes a posthumanist, site-led mode of reasoning in which geological, ecological, climatic, and human forces participate in shaping artistic practice. It draws on Quarry Sonnets, a nine-day, practice-led field project at the Vale de Meios limestone quarry in Portugal’s Serras de Aire e Candeeiros Natural Park in late November 2022, involving forty-five participants from six European art schools. Treating art practice as a way of knowing, the project convened open, revisable ways of working—walking, listening, iterative making, and collective reflection—so that the quarry’s tempos, weather, fossils, and working traces could co-author inquiry. Methodologies were held lightly and adjusted in practice, with decisions led by what the site made possible on a given day rather than preset outcomes. Two orienting commitments—attunement and composting knowledge—held diverse practices and partial understandings in contact without forcing consensus. The article’s contribution is to foreground artistic practice as a way of organizing environmental research by expanding who participates and what counts as evidence, while refusing closure into templates, solutions, or toolkits. In this register, research proceeds with the quarry and its more-than-human relations as a co-author that sets pace and constraint, keeping political and ecological questions active without resolving them in advance.