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- Mechanical caracterisation of polyester resin and corn natural fibers compositePublication . Queijo, Luis; Rocha, JoãoThe use of natural fibers as reinforcement in polymer matrix composites is gaining popularity in the development of renewable products. Although glass and other synthetic fiber-reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. The work deals with the characteristics of fiber composites that can offer several advantages, like low cost, weight savings and relatively good mechanical properties. It focuses on the effects of corn fibers as reinforcement agents in composites. Mechanical testing was performed to qualify the reinforcement properties of the corn fibers and consequently to compare with fiberglass composites.
- Mechanical characterisation of cytisus scoparius natural fibres – a preliminaryPublication . Queijo, Luis; Rocha, João; Ribeiro, J.E.The use of natural fibres as reinforcement in polymeric matrix composites is gaining popularity sustained not only by a logical search of more ecological alternatives to the conventional fibres in the development of renewable products but also by economic reasons. Although the conventional glass and other synthetic fibre-reinforced plastics possess high specific strength, their fields of application are limited because of their inherent higher production cost and their lack of recycling possibilities. The use of natural fibres from autochthones plants without commercial value for “green” composites production should be enhanced once the higher value-in-use may mean increasing the content of a local material (a natural fibre) in the local production of a part (a composite) [1]. This work’s objective is to provide one first approach to mechanical characterisation of scotch broom (Cytisus Scoparius) natural fibres in order of its future use in natural fibre reinforced composites production. Fibres to be tested have been extracted from year scotch broom branches using traditional techniques that consisted in smashing the branches, a maceration period, rip them to remove the soft organic tissue and then naturally dry the obtained fibres. For natural fibres characterisation was develop a special mounting frames to allow them to be essayed according the ASTM D2343 – 09 standards [2]. From the extracted data in yield strength tests over scotch broom fibres it can be concluded that those represent a promising complimentary choice to other natural fibres in natural fibre reinforced composites manufacturing, whose application can be settled as medium strength appliances. Also, usually local non-valuable resource is explored contributing to forest residues cleaning with added benefits. This works is being followed by polymeric composite plates production, using these fibres, with a random orientation, as a first approach, and then with usual defined orientations and its testing in order to realise which mechanical characteristics can be expected as a composite.
- Análise biomecânica da influência do calçado desportivo na corridaPublication . Brochado, Joana; Queijo, Luis; Rocha, JoãoA prática da corrida tem vindo a conquistar cada vez mais adeptos a cada ano e, consequente a este aumento do número de corredores, também ocorreu o aumento e aprimoramento dos equipamentos de corrida, nomeadamente do calçado desportivo. Os poucos estudos que investigaram as respostas biomecânicas deste equipamento nesta prática desportiva são insuficientes para o entendimento da influência que o calçado pode exercer na corrida e, por essa razão, mais estudos precisam ser desenvolvidos para caracterizar as respostas do aparelho locomotor sob a influência do calçado utilizado. O presente estudo tem como objetivo estudar a influência do calçado desportivo na corrida, centrando-se no estudo biomecânico da corrida com diferentes tipos de calçado e diferentes tipos de amostra, de modo, a verificar se há registo de alterações significativas que contribuam para o aperfeiçoamento do apoio do pé. A análise final demonstrou que, de uma maneira geral, pode-se comprovar que a temperatura à superfície da pele (Tm) obtida com a utilização de calçado específico para passada neutra (CPN) é ligeiramente maior da obtida com a utilização de calçado específico para passada pronadora (CPP) (cerca de 0.4ºC). Verificou-se que, a média dos ângulos formados pelos indivíduos ao utilizar calçado específico para passada pronadora é menor, quer no início quer no fim, do que quando é utilizado calçado específico para passada neutra. Porém, com base neste estudo, não se pode afirmar que haja influência significativa do calçado na prática da corrida, devendo cada atleta adquirir um calçado que seja confortável e ajustado a si próprio.
- Maxilla bone evaluation and implant surgical planning in a periodontal disease patientPublication . Queijo, Luis; Rocha, João; Ramos, AndréKnowing the value of biomodeling techniques - associating medical image segmentation with additive manufacturing, as a complimentary diagnose mean in the bone evaluation in complex and sensible anatomical areas (Queijo et al., 2010) it has been possible to support the diagnostic of a 50 years old female patient suffering from periodontitis who has lost an large amount of maxilla bone. At same time, by determining quantity and quality of maxilla bone in the affected area, the surgical planning have been made recurring to complete and fractioned biomodels in order to correctly define implants placement.
- Analysis of the kinematics of gait of young adult female carryng a computer bag with single handlePublication . Rocha, João; Queijo, LuisThe aim of this study is to assess postural changes in young female adults carrying a personal computer and some auxiliary material in a shoulder bag. Images have been recorded in the frontal and sagittal planes. After recording, the anatomical landmarks were manually digitized with appropriate software. Analyzing the data and comparing the two situations - with and without carrying a load can be registered significant differences in posture and normal gait.
- Surgical training and post-surgery evaluation using rapid prototyped biomodelsPublication . Queijo, Luis; Rocha, João; Pereira, Paulo Miguel; San Juan, ManuelThe biomedical use of rapid prototyping technologies (RP) had great developments in the last years, especially as supportive tools for tissue growth, direct or supportive technology for implant fabrication or as tool for personalized biomodels production applied to studies, this research will focus on this last type of usage in continuation of previous work developed with RP as an aid of surgery procedures. Biomodels can play an important role as a complementary diagnostic method to medical staff (Queijo et al., 2010). The usage of RP technologies for biomodels production, in Lytic Spondylolisthesis surgical training and as a tool for post-surgery evaluation, is presented in this paper.
- Maxilla bone pre-surgical evaluation aided by 3D models obtained by rapid prototypingPublication . Queijo, Luis; Rocha, João; Barreira, Luísa; Ramos, André; San Juan, Manuel; Barbosa, Tiago M.For implant planning and placement, the association of CAD and CAM techniques furnishes some advantages, regarding 3D determination of the patient’s jaw anatomy and fabrication of both anatomical models and surgical guides (Verstreken et al. 1996). In this paper we will present Rapid Prototype (RP) use as a tool, able to produce solid models of a maxilla in order to allow pre-surgical conditions evaluation in a pa-tient who has lost bone tissue and needs dental implants. In this process, three-dimensional reconstruction has been made from a bi-dimensional image file, obtained by Computerized Tomography (CT) and a set of partial and total biomedical models have been manufactured to allow maxilla analysis. Rapid Prototyping technique used has been three-dimensional printing (TDP or 3DP) which allows a good reality simulation.
- Mechanical caracterisation of polyester and sunflower natural fiber compositePublication . Rocha, João; Queijo, LuisThe use of natural fibers as reinforcement in polymer matrix composites is gaining popularity in the development of renewable products. Although glass and other synthetic fiber-reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. This work deals with the characteristics of natural fiber composites that can offer several advantages, like low cost, weight savings and relatively good mechanical properties. It focuses on the effects of sunflower fibers as reinforcement agents in composites. Mechanical testing of Sunflower natural fibers composite was performed to qualify and quantify the reinforcement properties. At same time, Glass fiber composite sample tests have been produced and characterized and both results have been compared. From results comparison we can affirm that the produced polymeric sunflower fiber composite has adequate mechanical properties for lots of industrial applications even, as expected, these are lower than glass fiber composites. Using this natural fiber content this product become a more ecological substitute and environment friendly that the traditional polymeric glass fiber composites. For other way, once stems from sunflower plants are wastes that traditionally are left in the field, shredded and incorporated in to the soil, acting like natural low cost substrate, by collecting them and giving them some commercial value will make crops more profitable.
- A surgical training model manufacture using rapid prototyping technologyPublication . Queijo, Luis; Rocha, João; Barreira, Luísa; Barbosa, Tiago M.; Pereira, Paulo Miguel; San Juan, ManuelThe use of rapid prototyping has increasingly begun to reveal itself as a tool of great value in supporting medical activity. From two-dimensional medical images from computed tomography (CT) or magnetic resonance imaging (MRI) it is possible to obtain three-dimensional models. The models produced by rapid prototyping technologies are useful both in educational and medical-surgical environments. It can simplify the diagnosis of certain diseases, the development of complex surgical procedures, the prostheses and medical devices manufacture and the visualization of anatomical structures in educational environment.
- Estudo da marcha de crianças em idade escolar que transportam mochilas às costas usando cinemáticaPublication . Rocha, Daniela; Rocha, João; Barbosa, Tiago M.; Queijo, Luis; San Juan, ManuelEste estudo teve como objectivo analisar a cinemática do ciclo da marcha de crianças em idade escolar, transportando mochilas às costas. Foram estudadas 4 crianças (3 do sexo masculino e 1 do sexo feminino) do 3º ano do primeiro ciclo do ensino básico (8 anos idade). Cada criança caminhou num tapete rolante a velocidades incrementais (1.11 m.s-1, 1.38 m.s -1e 1.67 m.s -1) e com diferentes cargas relativas à massa corporal (0 %, 10 % e 20 %) numa mochila escolar. Todos os procedimentos foram filmados no plano sagital e frontal e tratados com software específico para análise cinemática do movimento humano. Foi efectuada a análise cinemática de um ciclo completo, para cada carga e velocidade. Foram avaliados os parâmetros gerais do ciclo da marcha, parâmetros de cinemática angular, assim como, parâmetros de cinemática linear. Como principais conclusões deste estudo pode-se afirmar que de 0 % para 10 % de carga os parâmetros seguem uma tendência e para cargas superiores a 10 % e com marcha mais rápida essa tendência não se mantém. Será portanto espectável que o valor de carga máxima a transportar na mochila esteja entre 10 e 20 % da massa corporal.
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