The influence of task design on upper limb muscles fatigue during low-load repetitive work: A systematic review

Ergonomic interventions such as increased scheduled breaks or job rotation have been proposed to reduce upper limb muscle fatigue in repetitive low-load work. This review was performed to summarize and analyze the studies investigating the effect of job rotation and work-rest schemes, as well as, work pace, cycle time and duty cycle, on upper limb muscle fatigue. The effects of these work organization factors on subjective fatigue or discomfort were also analyzed. This review was based on relevant articles published in PubMed, Scopus and Web of Science. The studies included in this review were performed in humans and assessed muscle fatigue in upper limbs. 14 articles were included in the systematic review. Few studies were performed in a real work environment and the most common methods used to assess muscle fatigue were surface electromyography (EMG). No consistent results were found related to the effects of job rotation on muscle activity and subjective measurements of fatigue. Rest breaks had some positive effects, particularly in perceived discomfort. The increase in work pace reveals a higher muscular load in specific muscles. The duration of experiments and characteristics of participants appear to be the factors that most have influenced the results. Future research should be focused on the improvement of the experimental protocols and instrumentation, in order to the outcomes represent adequately the actual working conditions. Relevance to industry: Introducing more physical workload variation in low-load repetitive work is considered an effective ergonomic intervention against muscle fatigue and musculoskeletal disorders in industry. Results will be useful to identify the need of future research, which will eventually lead to the adoption of best industrial work practices according to the workers capabilities.

Immediate effects of hip mobilization with movement in patients with hip osteoarthritis: A randomised controlled trial

Background Mobilization with movement (MWM) has been shown to reduce pain, increase range of motion (ROM) and physical function in a range of different musculoskeletal disorders. Despite this evidence, there is a lack of studies evaluating the effects of MWM for hip osteoarthritis (OA). Objectives To determine the immediate effects of MWM on pain, ROM and functional performance in patients with hip OA. Design Randomized controlled trial with immediate follow-up. Method Forty consenting patients (mean age 78 ± 6 years; 54% female) satisfied the eligibility criteria. All participants completed the study. Two forms of MWM techniques (n = 20) or a simulated MWM (sham) (n = 20) were applied. Primary outcomes: pain recorded by numerical rating scale (NRS). Secondary outcomes: hip flexion and internal rotation ROM, and physical performance (timed up and go, sit to stand, and 40 m self placed walk test) were assessed before and after the intervention. Results For the MWM group, pain decreased by 2 points on the NRS, hip flexion increased by 12.2°, internal rotation by 4.4°, and functional tests were also improved with clinically relevant effects following the MWM. There were no significant changes in the sham group for any outcome variable. Conclusions Pain, hip flexion ROM and physical performance immediately improved after the application of MWM in elderly patients suffering hip OA. The observed immediate changes were of clinical relevance. Future studies are required to determine the long-term effects of this intervention.

Adhesive thickness effects of a ductile adhesive by optical measurement techniques

Adhesive bonding is an excellent alternative to traditional joining techniques such as welding, mechanical fastening or riveting. However, there are many factors that have to be accounted for during joint design to accurately predict the joint strength. One of these is the adhesive layer thickness (tA). Most of the results are for epoxy structural adhesives, tailored to perform best with small values of tA, and these show that the lap joint strength decreases with increase of tA (the optimum joint strength is usually obtained with tA values between 0.1 and 0.2 mm). Recently, polyurethane adhesives were made available in the market, designed to perform with larger tA values, and whose fracture behaviour is still not studied. In this work, the effect of tA on the tensile fracture toughness (View the MathML source) of a bonded joint is studied, considering a novel high strength and ductile polyurethane adhesive for the automotive industry. This work consists on the fracture characterization of the bond by a conventional and the J-integral techniques, which accurately account for root rotation effects. An optical measurement method is used for the evaluation of crack tip opening (δn) and adherends rotation at the crack tip (θo) during the test, supported by a Matlab® sub-routine for the automated extraction of these parameters. As output of this work, fracture data is provided in traction for the selected adhesive, enabling the subsequent strength prediction of bonded joints.

Tensile fracture characterization of adhesive joints by standard and optical techniques

The use of adhesive joints has increased in recent decades due to its competitive features compared with traditional methods. This work aims to estimate the tensile critical strain energy release rate (GIC) of adhesive joints by the Double-Cantilever Beam (DCB) test. The J-integral is used since it enables obtaining the tensile Cohesive Zone Model (CZM) law. An optical measuring method was developed for assessing the crack tip opening (δn) and adherends rotation (θo). The proposed CZM laws were best approximated by a triangular shape for the brittle adhesive and a trapezoidal shape for the two ductile adhesives.

A simplified four-branch model for the analytical study of the out-of-plane performance of regular stone URM walls

During the last years, several studies have been made aiming to assess the out-of-plane seismic response of unreinforced stone masonry structures. This fact led to the development of a wide variety of models and approaches, ranging from simple kinematic based analytical models up to complex numerical simulations. Nevertheless, for the sake of simplicity, the out-of-plane seismic response of a masonry wall pier may be obtained by means of a simple single-degree-of-freedom system while still providing good results. In fact, despite the assumptions associated with such a simple formulation, it is also true that the epistemic uncertainty inherent with the selection of appropriate input parameters in more complex models may render them truly ineffective. In this framework, this paper focuses on the study of the out-of-plane bending of unreinforced stone masonry walls (cantilevers) by proposing a simplified analytical approach based on the construction of a linearized four-branch model, which is used to characterize the linear and nonlinear response of such structural elements through an overturning moment-rotation relationship. The formulation of the four-branch model is presented and described in detail and the meaningful parameters used for its construction are obtained from a set of experimental laboratory tests performed on six full-scale unreinforced regular sacco stone masonry specimens. Moreover, a parametric analysis aiming to evaluate the effect of these parameters’ variation on the final configuration of the model is presented and critically discussed. Finally, the results obtained from the application of the developed four-branch model on real unreinforced regular sacco stone masonry walls are thoroughly analysed and the main conclusions obtained from its application are summarized.

Proposta de Reconversão de linhas Ferroviárias para Linhas de Levitação Magnética Caso de Estudo Brasil

Trabalho realizado para a disciplina de Dissertação, Projeto ou Estágio do Instituto Superior Técnico de Engenharia do Porto, no ano letivo de 2014/2015, com a proposta de Dissertação no âmbito da transição das convencionais vias de ferrovia para as vias de levitação magnética, como parte dos requisitos à obtenção dos ECTS necessários à classificação final. Propõe-se nesta dissertação a aplicação de um sistema de levitação magnética que resulta da evolução dos sistemas existentes. A proposta exposta é uma melhoria que consiste numa possibilidade teórica de o trilho conseguir através do magnetismo, aplicar uma rotação ao veículo necessária em curva e ajustar essa rotação à velocidade a que se desloca. Para que este sistema funcione sugere-se a introdução de mais um campo magnético no trilho, que tem como função rodar o veículo em curva e substituir a sobrelevação ou escala do convencional trilho. Sugere-se que este sistema seja aplicado no território brasileiro em três fases distintas. Ligando numa primeira fase as três maiores cidades, seguido do litoral e por fim o interior do Brasil. A aplicação deste sistema no Brasil pode apresentar ser a solução ideal, em termos de velocidade e conforto, contudo é um sistema que necessita de estudos mais aprofundados.

Friction surfacing of aluminium alloys

Dissertação para a obtenção do grau de Mestre em Engenharia Mecânica

Estágio em Cuidados de Saúde Primários – A Opinião dos Internos de Pediatria

Introdução: O Estágio em Cuidados de Saúde Primários à Criança e ao Adolescente foi integrado no programa do Internato Complementar de Pediatria em 1996. Desde então, não foi revisto, apesar de vários aspectos relativos à sua realização suscitarem controvérsia. Objectivos: Conhecer a opinião dos internos relativamente ao estágio e, deste modo, contribuir para a revisão do programa de formação, em curso. Metodologia: Estudo transversal descritivo com aplicação de um questionário por via electrónica, aos internos de Pediatria e recém-especialistas, incidindo sobre três questões: parecer geral sobre o estágio actualmente preconizado, caracterização e opinião sobre o estágio realizado e perspectivas para o futuro. Resultados: Foram obtidas 68 respostas; 62/68 (91%) dos inquiridos concordam com a realização do estágio, mas 58/68 (85%) consideram-no demasiado longo e 18/68 (25%) pouco útil; 46/68 (68%) observaram crianças/adolescentes sem médico assistente atribuído e 36/68 (44%) consideram que o estágio foi maioritariamente não tutelado. Os aspectos positivos referidos foram a possibilidade de fazer a consulta de vigilância de forma longitudinal e de conhecer a realidade dos cuidados de saúde primários assim como o contacto com a saúde escolar e com a comunidade da criança. Os aspectos negativos incluíram a duração excessiva, a orientação inadequada, a ausência de um estágio estruturado e a má definição do papel do interno. Conclusões: O grau de insatisfação com o Estágio em Cuidados de Saúde Primários à Criança e ao Adolescente foi elevado, ficando clara a necessidade de instituir modificações relativamente à duração, programa e orientação do estágio. Com base nas opiniões dos inquiridos, é apresentado um conjunto de propostas para a reformulação do estágio.

Endoscopic Treatment of Early Gastric Obstruction After Sleeve Gastrectomy: Report of Two Cases

Morbid obesity is an epidemic and complex disease which imposes a multidisciplinary approach. Laparoscopic sleeve gastrectomy has become a frequent procedure given its effi- cacy and safety compared to other surgical options. However, it isn’t free from complications. Lax gastric fixation or incorrect positioning of the stomach during surgery can result in early gastric outlet obstruction caused by a volvulus-like mechanism by rotation of the stomach around its anatomic axes. This report refers to two cases of post sleeve gastric torsion resulting in persisting vomiting after initiating oral intake. The diagnosis was confirmed by upper gastrointestinal-contrast study and gastroscopy. In both cases, a fully covered self-expandable metallic stentwas insertedwhich prompted the gastric lumen to become permeable resulting in symptomatic resolution. The stents were removed endoscopically aftertwo and three months. Beyond more than three years offollow-up,the patients remain asymptomatic and no recurring ‘‘stenosis’’ was noticed.In these cases the use offully covered self-expandable metallic stents demonstrated to be effective and safe in the treatment of post sleeve gastric torsion.

Joining copper to stainless steel by friction stir diffusion process

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Engenharia Mecânica

Range of motion measurements based on depth camera for clinical rehabilitation

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

Urban deforestation and urban development

This paper has developed a model of a single forest owner operating with perfect foresight in a dynamic open-city environment that allows for switching between alternative competing land uses (forest and urban use) at some point in the future. The model also incorporates external values of an even-aged standing forest in addition to the value of timber when it is harvested. Timber is exploited based on a multiple rotation model a la Faustmann with clear-cut harvesting. In contrast to previous models, our alternative land use to forest land is endogenous. Within this framework, we study the problem of the private owner as well as that of the social planner, when choosing the time to harvest, the time to convert land and the intensity of development. We also examine the extent to which the two-way linkage between urban development and forest management practices (timber production and provision of forest amenities) contributes to economic efficiency and improvements in non-market forest benefits. Finally, we consider policy options available to a regulator seeking to achieve improvements in efficiency including anti-sprawl policies (impact fees and density controls) and forest policies such a yield tax. Numerical simulations illustrate our analytical results.

Urban containment: An effective tool for environmental protection?

This paper examines the effectiveness of urban containment policies to protect forestland from residential conversion and to increase the provision of forest public goods in the presence of irreversible investments and policy uncertainty. We develop a model of a single landowner that allows for switching between competing land uses (forestry and residential use) at some point in the future. Our results show that urban containment policies can protect (even if temporarily) forestland from being developed but must be supplemented with policies that influence the length and number of harvesting cycles if the goal is to increase nontimber benefits. The threat of a development prohibition creates incentives for preemptive timber harvesting and land conversion. In particular, threatened regulation creates an incentive to shorten rotation cycles to avoid costly land-use restrictions. However, it has an ambiguous effect on forestland conversion as the number of rotation cycles can also be adjusted to maximize the expected returns to land. Finally, in the presence of irreversibility, forestland conversion decisions should be done using real option theory rather than net present value analysis

Hole cleaning performance monitoring during the drilling of directional wells

During drilling operation, cuttings are produced downhole and must be removed to avoid issues which can lead to Non Productive Time (NPT). Most of stuck pipe and then Bottom-Hole Assembly (BHA) lost events are hole cleaned related. There are many parameters which help determine hole cleaning conditions, but a proper selection of the key parameters will facilitate monitoring hole cleaning conditions and interventions. The aim of Hole Cleaning Monitoring is to keep track of borehole conditions including hole cleaning efficiency and wellbore stability issues during drilling operations. Adequate hole cleaning is the one of the main concerns in the underbalanced drilling operations especially for directional and horizontal wells. This dissertation addresses some hole cleaning fundamentals which will act as the basis for recommendation practice during drilling operations. Understand how parameters such as Flowrate, Rotation per Minute (RPM), Rate of Penetration (ROP) and Mud Weight are useful to improve the hole cleaning performance and how Equivalent Circulate Density (ECD), Torque & Drag (T&D) and Cuttings Volumes coming from downhole help to indicate how clean and stable the well is. For case study, hole cleaning performance or cuttings volume removal monitoring, will be based on real-time measurements of the cuttings volume removal from downhole at certain time, taking into account Flowrate, RPM, ROP and Drilling fluid or Mud properties, and then will be plotted and compared to the volume being drilled expected. ECD monitoring will dictate hole stability conditions and T&D and Cuttings Volume coming from downhole monitoring will dictate how clean the well is. T&D Modeling Software provide theoretical calculated T&D trends which will be plotted and compared to the real-time measurements. It will use the measured hookloads to perform a back-calculation of friction factors along the wellbore.

A SDK improvement towards gesture support

Human-Computer Interaction have been one of the main focus of the technological community, specially the Natural User Interfaces (NUI) field of research as, since the launch of the Kinect Sensor, the goal to achieve fully natural interfaces just got a lot closer to reality. Taking advantage of this conditions the following research work proposes to compute the hand skeleton in order to recognize Sign Language Shapes. The proposed solution uses the Kinect Sensor to achieve a good segmentation and image analysis algorithms to extend the skeleton from the extraction of high-level features. In order to recognize complex hand shapes the current research work proposes the redefinition of the hand contour making it immutable to translation, rotation and scaling operations, and a set of tools to achieve a good recognition. The validation of the proposed solution extended the Kinects Software Development Kit to allow the developer to access the new set of inferred points and created a template-matching based platform that uses the contour to define the hand shape, this prototype was tested in a set of predefined conditions and showed to have a good success ration and has proven to be eligible for real-time scenarios.