Projeto e desenvolvimento de equipamentos mecânicos na empresa Matechnics

No âmbito do Mestrado em Engenharia Mecânica, área de especialização em Construção e Manutenção de Equipamentos e Sistemas Mecânicos, do Instituto Superior de Engenharia de Coimbra, realizou-se um estágio curricular na empresa Matechnics. Esta empresa dedica-se ao projeto e construção de soluções na área de automação, robótica e à prestação de serviços de manutenção industrial e eletricidade. O estágio realizado inseriu-se no departamento técnico, nomeadamente na área de projeto mecânico dos equipamentos que desenvolve. O presente relatório de estágio apresenta a descrição de alguns processos de fabrico utilizados no estágio, nomeadamente o torneamento no torno convencional e a fresagem em centros de maquinagem, alguns projetos desenvolvidos na empresa, tais como, uma flange de ligação entre uma bomba hidráulica e um motor, um dispositivo elevatório de tampa de um reservatório cilíndrico e bomba hidráulica, uma garra manipuladora para transporte de válvulas, uma maquete 3D de uma estufa de alívio de tensões residuais bem como, descrição da tecnologia utilizada e um desgasificador de resina. Este relatório visa, essencialmente, a descrição do projeto, o desenho e o desenvolvimento de todos os componentes desenvolvidos associados ao estágio curricular realizado. Também faz alusão a estudos numéricos realizados, dos esforços exercidos em alguns dos componentes elaborados. Os estudos numéricos realizaram-se através da ferramenta de simulação por elementos finitos do software Solidworks®. A partir destes estudos podem ser calculadas as tensões máximas exercidas e os deslocamentos a que os componentes estão sujeitos

Waist circumference as a mediator of biological maturation effect on the motor coordination in children

AbstractObjectiveThe present study aimed to: 1) examine the association of biological maturation effect on performance at a motor coordination battery and 2) to assess whether the association between biological maturation and scores obtained in motor coordination tests is mediated by some anthropometric measurement.MethodsThe convenience sample consisted of 73 male children aged 8 years old. Anthropometric data considered the height, body mass, sitting height, waist circumference, body mass index, fat mass and fat-free mass estimates. Biological maturation was assessed by the percentage of the predicted mature stature. Motor coordination was tested by the Körperkoordinationstest für Kinder. A partial correlation between anthropometric measurements, z-score of maturation and the motor coordination tests were performed, controlling for chronological age. Finally, causal mediation analysis was performed.ResultsHeight, body mass, waist circumference and fat mass showed a slight to moderate inverse correlation with motor coordination. Biological maturation was significantly associated with the balance test with backward walking (r=−0.34). Total mediation of the waist circumference was identified in the association between biological maturation and balance test with backward walking (77%).ConclusionsWe identified an association between biological maturation and KTK test performance in male children and also verified that there is mediation of waist circumference. It is recommended that studies be carried out with female individuals and at other age ranges

Longitudinal study of repeated sprint performance in youth soccer players of contrasting skeletal maturity status

The purpose of the study was to evaluate the developmental changes in performance in a repeated-sprint ability (RSA) test in young soccer players of contrasting maturity status. A total of 83 regional level Portuguese youth soccer players, aged 11-13 years at baseline was assessed annually. Stature, body mass, 7x34.2-m sprint protocol (25-s active recovery), 20-m multi-stage continuous shuttle endurance run and counter-movement jump (CMJ) without the use of the arms were measured. Fat-free mass (FFM) was determined by age and gender-specific formulas. Developmental changes in total sprint time across ages were predicted using multilevel modeling. Corresponding measurements were performed on an independent cross-sectional sub-sample of 52 youth soccer players 11-17 years to evaluate the predictive model. CA, CA(2), maturational status (SA-CA), body size (mass and stature), FFM, aerobic endurance, lower limb explosive strength and annual volume training significantly improved the statistical fit of the RSA multilevel model. In 'late' maturing athletes, the best model for predicting change in RSA was expressed by the following equation: 86.54 - 2.87 x CA + 0.05 x CA(2) - 0.25 x FFM + 0.15 x body mass + 0.05 x stature - 0.05 x aerobic endurance - 0.09 x lower limb explosive strength - 0.01 x annual volume training. The best fitting models for players who were 'on time' and 'early' maturing were identical to the best model for late maturing players, less 0.64 seconds and 1.74 seconds, respectively. Multilevel modeling provided performance curves that permitted the prediction of individual RSA performance across adolescent years in regional level soccer players

Multivariate relationships among morphology, fitness and motor coordination in prepubertal girls

Motor coordination and physical fitness are multidimensional concepts which cannot be reduced to a single variable. This study evaluated multivariate relationships among morphology, physical fitness and motor coordination in 74 pre-pubertal girls 8.0-8.9 years of age. Data included body dimensions, eight fitness items and four motor coordination tasks (KTK battery). Maturity status was estimated as percentage of predicted mature stature attained at the time of observation. Canonical correlation analysis was used to examine the relationships between multivariate domains. Significant pairs of linear functions between indicators of morphology and fitness (r(c) = 0.778, Wilks' Lambda = 0.175), and between fitness and motor coordination (r(c) = 0.765, Wilks' Lambda = 0.289) were identified. Girls who were lighter and had a lower waist-to-stature ratio and % fat mass attained better scores in the endurance run, sit-ups and standing long jump tests, but poorer performances in hand grip strength and 2-kg ball throw. Better fitness test scores were also associated with better motor coordination scores. Relationships between body size and estimated fatness with motor fitness suggested an inverse relationship that was particularly evident in performance items that required the displacement of the body through space, while motor coordination was more closely related with fitness than with somatic variables

<b> Longitudinal data and hierarchical modeling. A tutorial for sport sciences researchers </b>

This paper was prepared to be a tutorial on ways of approaching longitudinal data. The main aim is to help researchers to use Hierarchical or Multilevel Modelling (HMM) to extract all the information their data contain. In the first part, we present the fundamental ideas of HMM applied to longitudinal data. The following part shows a complex example illustrating all steps in HMM as well as the analyses of all statistics given by the HLM 6.0 software package. <p> <b> RESUMO </b> Este texto pretende ser um auxiliar didáctico sobre modos de olhar informação de natureza longitudinal. O seu propósito fundamental é auxiliar os investigadores a recorrerem à Modelação Hierárquica ou Multinível (MHMN) para extraírem dos dados toda a sua riqueza. Na primeira parte apresentaremos as ideias fundamentais da MHMN aplicadas a dados longitudinais. De seguida recorreremos a um exemplo complexo para apresentar todos os passos da MHMN, interpretando de modo substantivo as principais estatísticas produzidas pelo software HLM 6.0

<b> Analysis and interpretation of physical activity levels in children: a tutorial based on hierarchical or multilevel modelling </b>

Este tutorial pretende apresentar, de modo didáctico, uma forma alternativa de análise de dados sobre os níveisde actividade física de crianças a partir da modelação hierárquica ou multinível. São mencionadas as diferentes etapas damodelação, os resultados são interpretados com base nos output´s do software utilizado – o HLM 6.02. Em cada etapa dopercurso são lançadas as hipóteses mais importantes em grau de complexidade crescente. A sua importância é referidaa partir dos resultados disponíveis. ABSTRACT This tutorial aims at a didactical presentation of an alternative approach to analyse physical activity data of childrenbased on hierarchical or multilevel modelling. We present the basic steps of the data analysis, interpreting all relevant outputfrom the chosen software – HLM 6.02. Each step is duly presented and explained, going from simple hypothesis to morecomplex ones. Their relevancy is presented in terms of the available results

Maduración biológica y fuerza muscular: Análisis de mediación en niñas prepúberes

Introduction: Biological maturation has been related to the level of physical activity and motor competence of children. Objectives: This study aimed to: 1) analyze the association between biological maturation and performance in muscular strength tests and 2) examine whether the relationship between maturation and performance in physical tests is mediated by anthropometric variables. Method: The sample was composed of 71 eight-year-old Brazilian girls. Anthropometry considered stature, body mass, waist circumference, estimated fat mass and fat-free mass. Biological maturation was assessed based on the percentage of predicted adult stature. The physical tests consisted of 2-kg medicine ball throw, handgrip strength, sit-ups and standing long jump. Pearson’s correlation test was conducted between the study variables and the last stage consisted of a causal mediation analysis. Results: Biological maturation was significantly associated with the 2-kg medicine ball throw (r=0.52) and handgrip strength (r=0.42) tests. In the 2-kg medicine ball throw, the relationship with maturation was mediated by body mass (total mediation, Sobel’s Test = 2.214, p<0.05) and by estimated lean mass (total mediation; Sobel’s Test = 3.146, p<0.001). In the handgrip strength test, body mass was the only mediating variable (total mediation; Sobel’s Test = 2.251, p<0.05). Conclusions: Advanced maturational status appears to contribute to the performance of prepubescent girls in muscular strength tests in which there is no translocation of total or partial body mass. It is recommended that studies be conducted in other age groups. Level of Evidence III; Study of nonconsecutive patients; without consistently applied reference ‘‘gold’’ standard.Introdução: A maturação biológica tem sido relacionada com o nível de atividades físicas e a competência motora das crianças. Objetivos: O presente estudo teve como objetivos: 1) analisar a associação da maturação biológica com o desempenho em testes de força muscular e 2) examinar se a relação entre o estado maturacional e o desempenho nos testes físicos é mediada por variáveis antropométricas. Método: A amostra foi composta por 71 meninas brasileiras com oito anos de idade. A antropometria considerou estatura, massa corporal, perímetro da cintura, estimativas de massa gorda e massa magra. A maturação biológica foi avaliada através do percentual da estatura matura predita. Os testes físicos aplicados consistiam em lançamento-2kg, preensão manual, abdominais e salto horizontal. A correlação de Pearson foi realizada entre as variáveis do estudo e, por último, a análise de mediação causal. Resultados: A maturação biológica associou-se significativamente à prova de lançamento-2kg (r=0,52) e preensão manual (r=0,42). No teste de lançamento-2kg, a relação com o estado maturacional foi mediada pela massa corporal (mediação total; Teste de Sobel=2,214, p<0,05) e pela estimativa de massa magra (mediação total; Teste de Sobel=3,146, p<0,001). Já no teste de preensão manual, a massa corporal foi a única variável mediadora (mediação total; Teste de Sobel=2,251, p<0,05). Conclusões: O estado maturacional avançado parece contribuir com o desempenho de meninas pré-púberes em testes de força muscular em que não há translocação da massa corporal total ou parcial. Recomenda-se que sejam realizados estudos em outras faixas etárias. Nível de Evidência III; Estudo de pacientes não consecutivos; sem padrão de referência “ouro” aplicado uniformemente.Introducción: La maduración biológica ha sido relacionada con el nivel de actividades físicas y la competencia motora de los niños. Objetivos: El presente estudio tuvo como objetivos: 1) analizar la asociación de la maduración biológica con el desempeño en tests de fuerza muscular y 2) examinar si la relación entre el estado de maduración y el desempeño en los tests físicos es mediada por variables antropométricas. Métodos: La muestra fue compuesta por 71 niñas brasileñas con ocho años de edad. La antropometría consideró estatura, masa corporal, perímetro de cintura, estimaciones de masa grasa y masa magra. La maduración biológica fue evaluada a través del porcentual de la estatura madura predicha. Los tests físicos aplicados consistían en lanzamiento-2kg, prensión manual, abdominales y salto horizontal. La correlación de Pearson fue realizada entre las variables del estudio y, por último, el análisis de mediación causal. Resultados: La maduración biológica se asoció significativamente al test de lanzamiento-2kg (r = 0,52) y prensión manual (r = 0,42). En el test de lanzamiento-2kg, la relación con el estado de maduración fue mediada por la masa corporal (mediación total, Test de Sobel = 2,214, p<0,05) y por la estimativa de masa magra (mediación total, Test de Sobel = 3,146, P<0,001). Ya en el test de prensión manual, la masa corporal fue la única variable mediadora (mediación total, Test de Sobel = 2,251, p<0,05). Conclusiones: El estado de maduración avanzado parece contribuir con el desempeño de niñas prepúberes en tests de fuerza muscular en los que no hay translocación de la masa corporal total o parcial. Se recomienda que sean realizados estudios en otros grupos de edad. Nivel de Evidencia III; Estudio de pacientes no consecutivos; sin estándar de referencia “oro” aplicado uniformement

Reproducibility of isokinetic strength assessment of knee muscle actions in adult athletes: Torques and antagonist-agonist ratios derived at the same angle position.

The current study aimed to examine the reliability of the conventional and functional ratios derived from peak torques (PTs) and those obtained from the combination of knee flexors torque at the angle of knee extensors PT. Twenty-six male athletes (mean of 24.0±0.7 years) from different sports completed a test-to-test variation in isokinetic strength (Biodex, System 3) within a period of one week. Anthropometry and body composition assessed by Dual Energy X-ray Absorptiometry were also measured. The proposed isokinetic strength ratio measurements appeared to be highly reliable: conventional ratio at PT angle (intra-class correlation, ICC = 0.98; 95% confidence interval; 95%CI: 0.95 to 0.99); functional extension ratio at PT angle (ICC = 0.98; 95%CI: 0.96 to 0.99); and, functional flexion ratio at PT angle (ICC = 0.95; 95%CI: 0.89 to 0.98). Technical error of measurement (TEM) and associated percentage of the coefficient of variation (%CV) were as follows: conventional ratio at PT angle (TEM = 0.02; %CV = 4.1); functional extension ratio at PT angle (TEM = 0.02; %CV = 3.8); and, functional flexion ratio at PT angle (TEM = 0.03; %CV = 3.6). The current study demonstrated that the traditional and new obtained simple and combined isokinetic indicators seem highly reliable to assess muscle strength and function in adult male athletes. A single testing session seems to be sufficiently to obtain these isokinetic strength indicators

Waist circumference as a mediator of biological maturation effect on the motor coordination in children

Abstract Objective: The present study aimed to: 1) examine the association of biological maturation effect on performance at a motor coordination battery and 2) to assess whether the association between biological maturation and scores obtained in motor coordination tests is mediated by some anthropometric measurement. Methods: The convenience sample consisted of 73 male children aged 8 years old. Anthropometric data considered the height, body mass, sitting height, waist circumference, body mass index, fat mass and fat-free mass estimates. Biological maturation was assessed by the percentage of the predicted mature stature. Motor coordination was tested by the Körperkoordinationstest für Kinder. A partial correlation between anthropometric measurements, z-score of maturation and the motor coordination tests were performed, controlling for chronological age. Finally, causal mediation analysis was performed. Results: Height, body mass, waist circumference and fat mass showed a slight to moderate inverse correlation with motor coordination. Biological maturation was significantly associated with the balance test with backward walking (r=-0.34). Total mediation of the waist circumference was identified in the association between biological maturation and balance test with backward walking (77%). Conclusions: We identified an association between biological maturation and KTK test performance in male children and also verified that there is mediation of waist circumference. It is recommended that studies be carried out with female individuals and at other age ranges