Multi-Laser Multi-Material powder bed fusion - vision and strategies

Multi-Laser Multi-Material powder bed fusion – vision and strategies - apresentação da tecnologia Powder Bed FusionThis work was supported by FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020

Using multiple regression, neural networks and support vector machines to predict lamb carcasses composition

The objective of this work was to use a Data Mining (DM) approach to predict, using as predictors the car- cass measurements taken at slaughter line, the compo- sition of lamb carcasses. One hundred and twenty five lambs of Churra Galega Braganc ̧ana breed were slaugh- tered.During carcasses quartering, a caliper was used to perform subcutaneous fat measurements, over the max- imum depth of longissimus muscle (LM), between the 12th and 13th ribs (C12), and between the 1st and 2nd lumbar vertebrae (C1). The Muscle (MP), Bone (BP), Subcutaneous Fat (SFP), Inter-Muscular Fat (IFP), and Kidney Knob and Channel Fat (KKCF) proportions of lamb carcasses were computed. We used the rminer R library and compared three regression techniques: Mul- tiple Regression (MR), Neural Networks (NN) and Sup- port Vector Machines (SVM). The SVM model provided the lowest relative absolute error for the prediction of BP, SFP and KKCF, while MR presented the best pre- dictions for MP and IFP. Also, a sensitivity analysis procedure revealed the C12 measurement as the most relevant predictor for all five carcass tissues

A particle swarm-based algorithm for optimization of multi-layered and graded dental ceramics

The thermal residual stresses (TRSs) generated owing to the cooling down from the processing temperature in layered ceramic systems can lead to crack formation as well as influence the bending stress distribution and the strength of the structure. The purpose of this study is to minimize the thermal residual and bending stresses in dental ceramics to enhance their strength as well as to prevent the structure failure. Analytical parametric models are developed to evaluate thermal residual stresses in zirconia-porcelain multi-layered and graded discs and to simulate the piston-on-ring test. To identify optimal designs of zirconia-based dental restorations, a particle swarm optimizer is also developed. The thickness of each interlayer and compositional distribution are referred to as design variables. The effect of layers number constituting the interlayer between two based materials on the performance of graded prosthetic systems is also investigated. The developed methodology is validated against results available in literature and a finite element model constructed in the present study. Three different cases are considered to determine the optimal design of graded prosthesis based on minimizing (a) TRSs; (b) bending stresses; and (c) both TRS and bending stresses. It is demonstrated that each layer thickness and composition profile have important contributions into the resulting stress field and magnitude.info:eu-repo/semantics/publishedVersio

Multi-material additive manufacturing for advanced high-tech components

Multi-Material Additive Manufacturing for Advanced High-Tech Components is a new open Special Issue of Materials, which aims to publish original and review papers regarding new scientific and applied research and make great contributions to finding, exploring and understanding novel multi-material components via additive manufacturing [...]Project Moedinov—New aesthetics for collection coins by using advanced technologies with the reference POCI-01-0247-FEDER-033361

Novo método de avaliação dinâmica da articulação patelo-femoral em RM

A patologia patelo-femoral é uma das mais frequentes causas de consulta do joelho. A problemática desta articulação é reconhecidamente multifactorial. Apesar de estabelecidos vários factores de risco, tem sido globalmente assumida a necessidade de uma avaliação dinâmica e objectiva desta “articulação”, face a recorrentes erros diagnósticos. Revela-se essencial, quer no âmbito do diagnóstico, orientando a triagem patológica (e por conseguinte a escolha das terapias mais adequadas); quer ao nível do “follow-up” do paciente, nomeadamente para avaliação dos novos métodos cirúrgicos incluindo reconstruções do ligamento patelo-femoral medial (LPFM) para instabilidades objectivas. A hipótese deste estudo é que, da avaliação funcional dinâmica combinada com os factores morfológicos clássicos pode resultar a detecção de novos factores de risco e de avaliação funcional pós operatória da patelo-femoral

On the development of advanced methodologies to assist on the diagnosis of human articulations pathologies : a biomechanical approach

The main purpose of this investigation is to present a preliminary study on the development of advanced methodologies to assist on the diagnosis of human articulations pathologies. In this process, a biomechanical approach is considered to characterize the patellofemoral joint. The present research work involves two distinct scientific domains, respectively, engineering and health sciences, and arises as a result of an association between the Mechanical Engineering Department of the University of Minho and a Portuguese company of medical consulting, ESPMEN. The correlation of both of these areas takes part of the highest biomedical engineer’s research interests and professional ambitions. One area where this kind of approach is essential is in the understanding of patellofemoral disorders, due to their ambiguous definition, multifactorial aetiology and common thread with and impact on nearly all knee conditions. Thus, the present project represents an appealing challenge to all the involved parts. This paper describes the patellofemoral (PF) problems, from their physiopathology to epidemiology, focusing their critical question: the diagnosis, but from a conclusive perspective of resolution. Actually, since the majority of the PF cases are recurrently misdiagnosed, there is in fact an urgent need of standardization of the physical examination methods. The biomechanical approach should prospectively culminate in the development of a standard assessment methodology that could precisely diagnose the PF pathologies and moreover allow clinicians to apply the most accurate and personalized treatment to each patient.Fundação para a Ciência e a Tecnologia (FCT

On assessment of processing variables on vertical centrifugal casting technique

The aim of the present study is to investigate the influence of the vertical centrifugal casting technique over mechanical and metallurgical properties of a hypereutectic Al–18Si alloy. Due to the inherent vibration of the centrifugal casting technique, and in order to study and understand the individual effects of the equipment vibration and the centrifugal force itself (pressure or fluid dynamics), as well as the combined effect of both, three different tests were performed: gravity casting, gravity casting with vibration and centrifugal casting. It was concluded that the metallurgical and mechanical properties of castings obtained by the centrifugal casting process depend on the combined effect of the centrifugal pressure and/or fluid dynamics and on the inherent vibration of the technique itself. Correlations between the different casting techniques and obtained mechanical and metallurgical properties are presentedFCT - Fundação para a Ciência e Tecnologi

A superhydrophilic biomimicked ceramic-reinforced-polymer nanocomposite for enhanced slip resistance and adhesion

Slips and Falls (SFs) were not considered a major source of lethal injuries until recently. Two-third of SF accidents happen due to the presence of ice on the surface around countries with snowfall making it second prominent reason of fatal injuries. Nearly 70,000 serious SFs happen in Finland and Sweden every year, and about 17,000 people lose their lives in USA (annual 1 million cases). Approximately 83% of people in Russia and thousands of people fall during winter in the UK and die as per HSE-UK. WHO-2021 recorded 37.3 million SFs cases demanding medical attention including millions requiring intensive care which resulted into permanent injuries, trauma, loss of limbs, loss of jobs, and burden on insurance and healthcare. Huge monetary deficits were recorded in Finland as €2.4 billion, €280 million in Sweden, £42 million in the UK occurred due to SFs. USA and Canada spend more than $55 billions annually on healthcare due to SFs. An effective anti-slipping shoe-sole can prevent and avoid these mishaps. Shoe-sole design modifications like tread patterns, crampons, studs, spikes etc. or material variations to improve friction between the sole-ice interface have been utilised. Though crampons/spikes/studs are effective, they are unsuitable for indoor usages, physically challenged and children. Whereas material-based solutions lose their effectiveness due to quick wear or in the presence of wet ice with quasi-liquid layer. We introduce nano-powder based ceramic reinforced composite patterned with Laser Surface Texturing (LST). Patterns are nature-inspired and are adapted from gecko/frog toepad structures that offer excellent friction on dry and wet surfaces. This innovation is a combination of material and design modifications and is not limited to anti-slipping shoe-soles. E-skin, drug delivery, wound healing, and electronic sensor patches face severed adhesion due to handling of body fluid and perspiration at the interface. Silicone Rubber polymer and proven anti-bacterial nano powders of zirconia and/or titania were mixed, vulcanised and textured to produce microfibrillar structure. This composite is highly wettable, wear-resistant, and adhering to wet and dry surfaces by creating capillary bridges. The capillary bridges provide mechanical interlocking on icy surfaces and serve as suction locations for patches to absorb and evaporate the bodily exudations out. We used five zirconia compositions (1, 3, 5, 7, and 9% by weight) producing composite with three sizes of capillary cavities to obtain best capillary effect. The findings of the study include average Shore-A hardness (32 to 40), morphology and topography, parametric optimisation of LST parameters, and wettability analysis. Obtained nano composite has excellent physicochemical superhydrophilicity (absorption of water droplet within 50 milliseconds after contact) with high static and kinetic friction coefficients of 2.5 and 1.62, respectively on wet ice suitable for mentioned applications

Dry sliding wear behaviour of Ti-TiB-TiNx in-situ composite synthesised by reactive hot pressing

Ti and its alloys are attractive materials for a variety of fields; however, a major problem of Ti and its alloys is their poor wear resistance. It is known that reinforcing Ti with hard ceramic phases can substantially improve the wear resistance. Thus, Ti-TiB-TiNx in-situ metal matrix composites were synthesised by reactive hot pressing utilising Ti/BN powder blends with 23:1 Ti:BN weight ratio. Ball-on-plate reciprocating dry sliding wear tests were performed against a 10 mm of alumina ball under 10 N normal load, at a frequency of 1 Hz, and with the total stroke length of 3 mm during 1,800 s. Results showed that the total wear volume loss was significantly decreased on the composite (11.4 +/- 2.0 x 10(-3) mm(3)) as compared to the unreinforced Ti (40.9 +/- 4.2 x 10(-3) mm(3)) due to the strengthening effect of the in-situ reinforcing phases.This study was supported by The Calouste Gulbenkian Foundation through Programa de Mobilidade Academica para Professores and Portuguese Foundation for Science and Technology (FCT-Portugal), under the project EXCL/EMS-TEC/0460/2012. The authors also would like to thank Prof. Amilcar Ramalho (Universidade de Coimbra) for the provision of profilometry facilities.info:eu-repo/semantics/publishedVersio

Porto Index Score: validação de novo método de avaliação ecográfica da patelo-femoral

A instabilidade patelo-femoral é uma das mais frequentes causas de consulta do joelho. O diagnóstico e classificação proposta pela escola de Lyon assenta nos achados clínicos e radiológicos incluindo TC (ou mais recentemente RM). A displasia da tróclea, altura da rótula, TA-GT e báscula patelar são classicamente assumidos como factores de risco major. A hipótese deste estudo é que, da avaliação funcional por ecografia é possível aferir uma correlação morfo-funcional pelo menos tão eficaz como pelos protocolos de TC ou RM com um custo significativamente mais baixo