Análise da relação entre intensidade da actividade física realiada com a sensação subjectiva de esforço na população com idade igual ou superior a 75 anos

RESUMO: Objectivo: O objectivo geral do estudo é analisar a relação entre intensidade da actividade física (AF) realizada pela população idosa com 75 anos ou mais, com a respectiva sensação subjectiva de esforço (SSE). Introdução: Em Portugal, e de acordo o Instituto Nacional de Estatística, em 2011 cerca de 19% da população tem mais de 65 anos. Em 2050, as estimativas apontam que esta percentagem seja de 25%, ou seja, um quarto do país. O envelhecimento propicía um declínio físico e funcional, e para o retardar estão recomendados 150 minutos por semana de AF moderada. A forma como tem sido avaliada a AF tem por base um pressuposto de comparação com valores de gasto energético de uma população com uma média de 40 anos. É fundamental a realização de estudos que analisem a associação entre o nível de intensidade de AF com a SSE, para aferir se esta comparação é transponível para esta faixa etária. Metodologia: Trata-se de um estudo observacional analítico transversal, com uma amostra constituída por 39 participantes, com uma mediana 77,0 anos de idade (percentil 25: 76,0; percentil 75: 80,0), sendo a mínima 75 e a máxima 86 anos. As variáveis são a SSE e a intensidade de cada actividade realizada. O protocolo de avaliação foi constituído pelo questionário de caracterização sóciodemográfica, Diário de AF e a Escala de Borg RPE 6-20. Resultados: Existe uma associação negativa significativa entre a idade e o gasto energético total (rs = -0,365, p=0,022) e uma associação negativa, moderada e significativa entre a idade e a SSE reportada média (rs = -0,521, p=0,001) e máxima (rs = -0,465, p=0,003). Observou-se uma associação positiva e significativa entre a SSE máxima diária e o tempo total dedicado a actividades físicas (r=0,367 e p=0,022) e o gasto energético total (r=0,569, p<0,001). Verificou-se igualmente que quanto maior o gasto energético total diário, maior a média da SSE (r=0,411; p=0,009). Existe uma concordância moderada e significativa (Kappa=0,475; p<0,001) entre a sensação reportada pelo participante e a classificação atribuída em cada actividade pelo Compêndio de Actividades Físicas (Ainsworth et al, 1993). No entanto, com uma tendência para a subestimação dos MET’s atribuídos a cada actividade Conclusão: Os resultados do estudo sugerem que existe uma associação positiva e significativa entre intensidade da AF realizada e a SSE, aquando da realização da mesma actividade. Apesar desta associação ser moderada, este estudo sugere que a classificação que o Compêndio utiliza não é directamente aplicável à população idosa com 75 anos ou mais.-------------ABSTRACT: Purpose: The overall objective of the study is to analyze the relationship between intensity of physical activity performed by the elderly population with 75 years or more with their subjective feeling of effort. Background: In Portugal, according with data from Instituto Português de Estatística, in 2011 aproximately 19% of the population has more than 65 years old. In 2050, estimates suggest that this percentage will be 25%, which means a quarter of the country. The way in which physical activity has been evaluated is based on a comparing assumption with values of energy expenditure in a population with an average of 40 years. It is critical to conduct studies to examine the association between the level of intensity of physical activity with the subjective feeling of effort, to assess whether this comparison is applied to this age group. Methods: This is a cross sectional observational study with a sample of 39 participants, with a median age of 77.0 years (25th percentile: 76.0; 75th percentile: 80.0), with the minimum age 75 years and maximum age 86 years. The variables are the subjective feeling of physical effort and intensity of each activity. It was applied one protocol evaluation consisting of a questionnaire of sociodemographic characteristics, A journal of physical activities and Borg RPE 6-20 scale. Results: There is a significant negative association between age and total energy expenditure (rs = -0.365, p = 0.022) and a negative, moderate and significant association between age and average (rs = -0.521, p = 0.001) and maximum subjective feeling of exertion reported (rs = -0.465, p = 0.003). There was a significant positive association between the subjective feeling of daily maximum effort and total time spent on physical activity (r = 0.367 and p = 0.022) and total energy expenditure (r = 0.569, p <0.001). It was also found that the higher the total daily energy expenditure, the higher the average of the subjective sense of effort (r = 0.411, p = 0.009). There is a moderate and significant correlation (kappa = 0.475, p <0.001) between the sensation reported by the participant and the rank assigned to each activity by Compendium of Physical Activities (Ainsworth et al, 1993). However, there is a tendency to over-estimate the subjective feeling of effort, or underestimation of METs assigned to each activity Conclusion: Study results suggest a positive and significant association between the level of intensity of physical activity and the subjective feeling of exertion, within the same activity. Even though this association is moderated, this study suggests that the Compendium of Physical Activities rating doesn’t suit for individuals with 75 years old or more.

Valorization of agroindustrial waste

The main objective of this work is the valorization of residues from agro-industry giving them an added value. The valorization was performed by using a "green" and sustainable solvent - supercritical fluid, in this case carbon dioxide. Two residues and one biomass were used to produce two different final products, thereby emphasizing the versatility of the waste recovery - spent coffee grounds and microalgae Chlorella protothecoides to produce biodiesel, and tomato pomace to extract carotenoids. In the first part of this work it was demonstrated the possibility to obtain a conversion of coffee spent grounds oil into biodiesel, through an enzymatic transesterification reaction, of 98.01% with the following operating conditions: molar ratio oil:methanol 1:24, residence time 0.8 min, pressure 25 MPa, temperature 313,15K. In this first phase, it was also used the microalgae Chlorella protothecoides, a biomass, to produce biodiesel and favorable results were obtained with this green process compared with a traditional process - basic catalysis / acid. In the second part of this work, by an extraction with supercritical CO2 it was obtained 3.38% oil from tomato pomace under the following conditions: pressure 35.1 MPa, temperature 313,15K. It was found that this oil contains various carotenoids: β-carotene, lutein and lycopene. The latter is present in larger amount.

Analysis and implementation of a multi-ratio switched capacitor DC-DC converter for a supercapacitor power supply

An energy harvesting system requires an energy storing device to store the energy retrieved from the surrounding environment. This can either be a rechargeable battery or a supercapcitor. Due to the limited lifetime of rechargeable batteries, they need to be periodically replaced. Therefore, a supercapacitor, which has ideally a limitless number of charge/discharge cycles can be used to store the energy; however, a voltage regulator is required to obtain a constant output voltage as the supercapacitor discharges. This can be implemented by a Switched-Capacitor DC-DC converter which allows a complete integration in CMOS technology, although it requires several topologies in order to obtain a high efficiency. This thesis presents the complete analysis of four different topologies in order to determine expressions that allow to design and determine the optimum input voltage ranges for each topology. To better understand the parasitic effects, the implementation of the capacitors and the non-ideal effect of the switches, in 130 nm technology, were carefully studied. With these two analysis a multi-ratio SC DC-DC converter was designed with an output power of 2 mW, maximum efficiency of 77%, and a maximum output ripple, in the steady state, of 23 mV; for an input voltage swing of 2.3 V to 0.85 V. This proposed converter has four operation states that perform the conversion ratios of 1/2, 2/3, 1/1 and 3/2 and its clock frequency is automatically adjusted to produce a stable output voltage of 1 V. These features are implemented through two distinct controller circuits that use asynchronous time machines (ASM) to dynamically adjust the clock frequency and to select the active state of the converter. All the theoretical expressions as well as the behaviour of the whole system was verified using electrical simulations.

Production of polyhydroxyalkanoates from oil-containing substrates

Different oil-containing substrates, namely, used cooking oil (UCO), fatty acids-byproduct from biodiesel production (FAB) and olive oil deodorizer distillate (OODD) were tested as inexpensive carbon sources for the production of polyhydroxyalkanoates (PHA) using twelve bacterial strains, in batch experiments. The OODD and FAB were exploited for the first time as alternative substrates for PHA production. Among the tested bacterial strains, Cupriavidus necator and Pseudomonas resinovorans exhibited the most promising results, producing poly-3-hydroxybutyrate, P(3HB), form UCO and OODD and mcl-PHA mainly composed of 3-hydroxyoctanoate (3HO) and 3-hydroxydecanoate (3HD) monomers from OODD, respectively. Afterwards, these bacterial strains were cultivated in bioreactor. C. necator were cultivated in bioreactor using UCO as carbon source. Different feeding strategies were tested for the bioreactor cultivation of C. necator, namely, batch, exponential feeding and DO-stat mode. The highest overall PHA productivity (12.6±0.78 g L-1 day-1) was obtained using DO-stat mode. Apparently, the different feeding regimes had no impact on polymer thermal properties. However, differences in polymer‟s molecular mass distribution were observed. C. necator was also tested in batch and fed-batch modes using a different type of oil-containing substrate, extracted from spent coffee grounds (SCG) by super critical carbon dioxide (sc-CO2). Under fed-batch mode (DO-stat), the overall PHA productivity were 4.7 g L-1 day-1 with a storage yield of 0.77 g g-1. Results showed that SCG can be a bioresource for production of PHA with interesting properties. Furthermore, P. resinovorans was cultivated using OODD as substrate in bioreactor under fed-batch mode (pulse feeding regime). The polymer was highly amorphous, as shown by its low crystallinity of 6±0.2%, with low melting and glass transition temperatures of 36±1.2 and -16±0.8 ºC, respectively. Due to its sticky behavior at room temperature, adhesiveness and mechanical properties were also studied. Its shear bond strength for wood (67±9.4 kPa) and glass (65±7.3 kPa) suggests it may be used for the development of biobased glues. Bioreactor operation and monitoring with oil-containing substrates is very challenging, since this substrate is water immiscible. Thus, near-infrared spectroscopy (NIR) was implemented for online monitoring of the C. necator cultivation with UCO, using a transflectance probe. Partial least squares (PLS) regression was applied to relate NIR spectra with biomass, UCO and PHA concentrations in the broth. The NIR predictions were compared with values obtained by offline reference methods. Prediction errors to these parameters were 1.18 g L-1, 2.37 g L-1 and 1.58 g L-1 for biomass, UCO and PHA, respectively, which indicates the suitability of the NIR spectroscopy method for online monitoring and as a method to assist bioreactor control. UCO and OODD are low cost substrates with potential to be used in PHA batch and fed-batch production. The use of NIR in this bioprocess also opened an opportunity for optimization and control of PHA production process.

The use of bone bridges in transtibial amputations

We sought to describe the bone bridge technique in adults, and present a variation for use in children, as well as to present its applicability as an option in elective transtibial amputations. This paper presents a prospective study of 15 transtibial amputations performed between 1992 and 1995 in which the bone bridge technique was employed. The patients' ages ranged from 8 to 48 years, with an average of 22.5 years. This technique consisted of the preparation of a cylinder of periosteum extracted from the tibia and with cortical bone fragments attached to it to promote a tibiofibular synostosis on the distal extremity of the amputation stump. We noted that the cortical bone fragments were dispensable when the technique was employed in children, due to the increased osteogenic capacity of the periosteum. This led to a variation of the original technique, a bone bridge without the use of the cortical bone fragments. RESULTS: The average time spent with this procedure, without any significant variation between adults and children, was 171 minutes. The adaptation to the definitive prosthesis was accomplished between 20 and 576 days, with an average of 180 days. Revision of the procedure was necessary in 3 amputations. CONCLUSIONS: This technique may be employed in transtibial amputations in which the final length of the stump lies next to the musculotendinous transition of the gastrocnemius muscle, as well as in the revision of amputation stumps in children, where the procedure has been shown to be effective in the prevention of lesions due to excessive bone growth.

Control in distribution networks with demand side management

The way in which electricity networks operate is going through a period of significant change. Renewable generation technologies are having a growing presence and increasing penetrations of generation that are being connected at distribution level. Unfortunately, a renewable energy source is most of the time intermittent and needs to be forecasted. Current trends in Smart grids foresee the accommodation of a variety of distributed generation sources including intermittent renewable sources. It is also expected that smart grids will include demand management resources, widespread communications and control technologies required to use demand response are needed to help the maintenance in supply-demand balance in electricity systems. Consequently, smart household appliances with controllable loads will be likely a common presence in our homes. Thus, new control techniques are requested to manage the loads and achieve all the potential energy present in intermittent energy sources. This thesis is focused on the development of a demand side management control method in a distributed network, aiming the creation of greater flexibility in demand and better ease the integration of renewable technologies. In particular, this work presents a novel multi-agent model-based predictive control method to manage distributed energy systems from the demand side, in presence of limited energy sources with fluctuating output and with energy storage in house-hold or car batteries. Specifically, here is presented a solution for thermal comfort which manages a limited shared energy resource via a demand side management perspective, using an integrated approach which also involves a power price auction and an appliance loads allocation scheme. The control is applied individually to a set of Thermal Control Areas, demand units, where the objective is to minimize the energy usage and not exceed the limited and shared energy resource, while simultaneously indoor temperatures are maintained within a comfort frame. Thermal Control Areas are overall thermodynamically connected in the distributed environment and also coupled by energy related constraints. The energy split is performed based on a fixed sequential order established from a previous completed auction wherein the bids are made by each Thermal Control Area, acting as demand side management agents, based on the daily energy price. The developed solutions are explained with algorithms and are applied to different scenarios, being the results explanatory of the benefits of the proposed approaches.

Optimization of wastewater quality in the Sines refinery

In order to address and resolve the wastewater contamination problem of the Sines refinery with the main objective of optimizing the quality of this stream and reducing the costs charged to the refinery, a dynamic mass balance was developed nd implemented for ammonia and polar oil and grease (O&G) contamination in the wastewater circuit. The inadequate routing of sour gas from the sour water stripping unit and the kerosene caustic washing unit, were identified respectively as the major source of ammonia and polar substances present in the industrial wastewater effluent. For the O&G content, a predictive model was developed for the kerosene caustic washing unit, following the Projection to Latent Structures (PLS) approach. Comparison between analytical data for ammonia and polar O&G concentrations in refinery wastewater originating from the Dissolved Air Flotation (DAF) effluent and the model predictions of the dynamic mass balance calculations are in a very good agreement and highlights the dominant impact of the identified streams for the wastewater contamination levels. The ammonia contamination problem was solved by rerouting the sour gas through an existing clogged line with ammonia salts due to a non-insulated line section, while for the O&G a dynamic mass balance was implemented as an online tool, which allows for prevision of possible contamination situations and taking the required preventive actions, and can also serve as a basis for establishing relationships between the O&G contamination in the refinery wastewater with the properties of the refined crude oils and the process operating conditions. The PLS model developed could be of great asset in both optimizing the existing and designing new refinery wastewater treatment units or reuse schemes. In order to find a possible treatment solution for the spent caustic problem, an on-site pilot plant experiments for NaOH recovery from the refinery kerosene caustic washing unit effluent using an alkaline-resistant nanofiltration (NF) polymeric membrane were performed in order to evaluate its applicability for treating these highly alkaline and contaminated streams. For a constant operating pressure and temperature and adequate operating conditions, 99.9% of oil and grease rejection and 97.7% of chemical oxygen demand (COD) rejection were observed. No noticeable membrane fouling or flux decrease were registered until a volume concentration factor of 3. These results allow for NF permeate reuse instead of fresh caustic and for significant reduction of the wastewater contamination, which can result in savings of 1.5 M€ per year at the current prices for the largest Portuguese oil refinery. The capital investments needed for implementation of the required NF membrane system are less than 10% of those associated with the traditional wet air oxidation solution of the spent caustic problem. The operating costs are very similar, but can be less than half if reusing the NF concentrate in refinery pH control applications. The payback period was estimated to be 1.1 years. Overall, the pilot plant experimental results obtained and the process economic evaluation data indicate a very competitive solution through the proposed NF treatment process, which represents a highly promising alternative to conventional and existing spent caustic treatment units.

Os médicos do trabalho e a nova organização da saúde e segurança do trabalho : quais as consequências na prática profissional? António de Sousa Uv

RESUMO - Em 1994/1995 o modelo legal de organização de serviços de Medicina do Trabalho instituído na década de 1960 foi substituído por uma nova superestrutura de serviços de Segurança, Higiene e Saúde dos Trabalhadores (SHST) nos locais de trabalho. O presente estudo pretende descrever e analisar em que medida o novo enquadramento jurídico de SHST, iniciado em 1994/1995 e correspondente genericamente à fase da Nova Saúde Ocupacional, foi acompanhado de alterações: (1) na percepção do grau de satisfação dos médicos do trabalho quanto ao seu papel e estatuto profissionais e (2) nas repercussões na sua prática profissional. O presente estudo (empírico, descritivo e comparativo) abrangeu um grupo de médicos do trabalho diplomados pela Escola Nacional de Saúde Pública (n = 153), de quem se recolheu, através de um questionário aplicado em 1993 e 2000, a opinião sobre as mudanças organizacionais da SHST. O papel e funções dos médicos do trabalho e as garantias de exercício profissional não se alteraram de forma importante, tendo a prática profissional da medicina do trabalho na modalidade «medicina do trabalho de empresa» (serviços internos e externos) diminuído, apesar de continuar a ser a forma de exercício predominante dos médicos do trabalho. O tempo dedicado à sua actividade situou-se num valor médio próximo das 20 horas semanais, sem alterações importantes entre 1993 e 2000. Concluiu-se que, no essencial, a publicação da nova legislação sobre organização de cuidados de MT/SHST/SO em 1994 e 1995 não reforçou significativamente as condições gerais de exercício da medicina do trabalho.

Reinvigorating and redesigning early intervention in psychosis services for young people in Auckland

RESUMO: Auckland tem sido pioneira na implementação de modelos de Intervenção Precoce em Psicose. No entanto, esta organização do serviço não mudou nos últimos 19 anos. Segundo os dados obtidos da utilização do serviço, no período de 1996 -2012 foram atendidos 997 doentes, que tinham um número médio de 89 contactos (IQR: 36-184), com uma duração média de 62 horas de contactos (IQR: 24-136). Estes doentes passaram um número médio de 338 dias (IQR: 93-757) em contacto com o programa. 517 doentes (52%) não necessitaram de internamento no hospital, e os que foram internados, ficaram uma mediana de 124 dias no hospital (IQR: 40-380). Os doentes asiáticos tiveram um aumento de 50% de probabilidade de serem internados no hospital. Este relatório inclui 15 recomendações para orientar as reformas para o serviço e, nomeadamente, delinear a importância de uma visão organizacional e dos seus componentes-chave. As recomendações incluem o reforço da gestão e da liderança numa estrutura de equipe mais integrada, com recursos dedicados a melhorar a consciencialização da comunidade, a educação e deteção precoce, bem como a capacidade de receber referenciações diretas. Os Indicadores Chave de Desempenho devem ser estabelecidos, mas os Exames de Estado Mental em risco, devem ser removidos. Auckland deve manter a faixa etária alvo atual. A duração do serviço deve ser aumentada para um mínimo de três anos, com a opção de aumentá-la para cinco anos. A proporção de gestor de cuidados para os doentes deve ser preconizada em 1:15, enquanto o pessoal de apoio não-clínico deve ser aumentado. Os psiquiatras devem ter uma carga de trabalho de cerca de 80 doentes por equivalente de tempo completo. Um serviço local de prestação de cuidados deve ser desenvolvido com, nomeadamente, intervenções culturais para responder às necessidades da população multicultural de Auckland. A capacidade de investigação deve ser incorporada no Serviço de Intervenção Precoce em Psicoses. Qualquer alteração deverá envolver contacto com todas as partes interessadas, e a Administração Regional de Saúde deve comprometer-se em tempo, recursos humanos e políticos para apoiar e facilitar a mudança do sistema, investindo de forma significativa para melhor servir a comunidade Auckland.----------------------------------- ABSTRACT: Auckland has been pioneering in the adoption of Early Intervention in Psychosis models but the design of the service has not changed in 19 years. In service utilisation data from 997 patients seen from 1996 -2012, patients had a median number of 89 contacts (IQR: 36-184), with a median duration of 62 hours of contact (IQR: 24-136). Patients spent a median number of 338 days (IQR: 93-757) in contact with the program. 517 patients (52%) did not require admission to hospital, and those who did spent a median of 124 days in hospital (IQR: 40-380). Asian patients had a 50% increased chance of being admitted to hospital. This report includes 15 recommendations to guide reforms to the service, including outlining the importance of vision and key components. It recommends strengthened managerial leadership and a more integrated team structure with dedicated resources for improved community awareness, education and early detection as well as the capacity to take direct referrals. Key Performance Indicators (KPIs) should be established but At Risk Mental States should be excluded. Auckland should maintain the current target age range. The duration of service should be increased to a minimum of three years, with the option to extend this to five years. The ratio of care co-ordinator to patients should be capped at 1:15 whilst non-clinical supporting staff should be increased. Psychiatrists should have a caseload of about 80 per FTE. A local Service Delivery framework should be developed, as should cultural interventions to meet the needs of the multicultural population of Auckland. Research capacity should be incorporated into the fabric of Early Intervention in Psychosis Services. Any changes should involve consultation with all stakeholders, and the DHB should commit to investing time, human and political resources to support and facilitate meaningful system change to best serve the Auckland community.

Dynamic range prediction for an electric vehicle

Electric Vehicles (EVs) have limited energy storage capacity and the maximum autonomy range is strongly dependent of the driver's behaviour. Due to the fact of that batteries cannot be recharged quickly during a journey, it is essential that a precise range prediction is available to the driver of the EV. With this information, it is possible to check if the desirable destination is achievable without a stop to charge the batteries, or even, if to reach the destination it is necessary to perform an optimized driving (e.g., cutting the air-conditioning, among others EV parameters). The outcome of this research work is the development of an Electric Vehicle Assistant (EVA). This is an application for mobile devices that will help users to take efficient decisions about route planning, charging management and energy efficiency. Therefore, it will contribute to foster EVs adoption as a new paradigm in the transportation sector.

A case study on the conversion of an internal combustion engine vehicle into an electric vehicle

This paper presents the conversion process of a traditional Internal Combustion Engine vehicle into an Electric Vehicle. The main constitutive elements of the Electric Vehicle are presented. The developed powertrain uses a three-phase inverter with Field Oriented Control and space vector modulation. The developed on-board batteries charging system can operate in Grid-to-Vehicle and Vehicle-to-Grid modes. The implemented prototypes were tested, and experimental results are presented. The assembly of these prototypes in the vehicle was made in accordance with the Portuguese legislation about vehicles conversion, and the main adopted solutions are presented.

A novel architecture of a bidirectional bridgeless interleaved converter for EV battery chargers

This paper presents a novel architecture of a bidirectional bridgeless interleaved converter for battery chargers of electric vehicles (EVs). The proposed converter is composed by two power stages: an ac-dc converter that is used to interface the power grid and the dc-link, and a dc-dc converter that is used to interface the dc-link and the batteries. The ac-dc converter is an interleaved bridgeless bidirectional boost-type converter and the dc-dc converter is a bidirectional buck-boost-type converter. The proposed converter works with sinusoidal grid current and with high power factor for all operating power levels, and in both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operation modes. In the paper is described in detail the proposed converter for EV battery chargers: the circuit topology, the principle of operation, the power control theory, and the current control strategy. Several simulation results for both G2V and V2G operation modes are presented.

A novel concept of unidirectional bridgeless combined boost-buck converter for EV battery chargers

This paper presents a novel concept of unidirectional bridgeless combined boost-buck converter for electric vehicles (EVs) battery chargers. The proposed converter is composed by two power stages: an ac-dc front-end converter used to interface the power grid and the dc-link, and a dc-dc back-end converter used to interface the dc-link and the batteries. The ac-dc converter is a bridgeless boost-type converter and the dc-dc converter is an interleaved buck-type converter. The proposed converter operates with sinusoidal grid current and unitary power factor for all operating power levels. Along the paper is described in detail the proposed converter for EV battery chargers: the circuit topology, the different stages describing the principle of operation, the power control theory, and the current control strategy, for both converters. Along the paper are presented several simulation results for a maximum power of 3.5 kW.

Ergonomic evaluation of office workplaces with Rapid Office Strain Assessment (ROSA)

The regular use of the computer in the office contributed to the appearance of many risk factors related with work-related musculoskeletal disorders (WRMSD) such as maintaining static sitting postures for long time and awkward postures of the head, neck and upper limbs, leading to increased muscle activity in the cervical spine and shoulders. The objective of this study was to evaluate the presence of risk factors for WRMSD in an office using the Rapid Assessment Office Strain method (ROSA). Based on the results of this ergonomic evaluation, an occupational gym program was designed and implemented. Thirty-eight workplaces were evaluated using the observation of the tasks and pictures records in order to characterize those tasks in more detail. The ROSA tool was applied by an observer, who selected the appropriate score based on the worker's posture as well as the time spent in each posture. Scores were recorded for the sections of the method, specifically Chair, Monitor and Mouse and Keyboard and Telephone. The scores were recorded in a sheet developed for the method. The mean ROSA final score was 3.61 ± 0.64, for Chair section was 3.45 ± 0.55, to Monitor and Telephone section was 3.11 ± 0.61, and to Mouse and Keyboard section was 2.11 ± 0.31. The results led to understand that the analyzed tasks represent situations of risk of discomfort and, according to the methods guidelines, further research and modifications of the workplace may be necessary. It should be emphasized that these scores may not be related to the poor available equipment but with the need to optimize their use by the workers. It was noticed also that the interaction of workers with the tasks and the adopted sitting posture at the computer throughout the day have effects at a muscular level, essentially for the cervical area and shoulders. ROSA tool is an useful and easy method to assess several risk factors associated with WRMSD, also allowing the design of specific occupational gym programs.

Renewable energy system for an isolated micro grid

This paper presents the development of the power electronics needed for the interaction between the electrical generator of a wind turbine and an isolated ac micro grid. In this system there are basically two types of receptors for the energy produced by the wind turbine, which are the loads connected to the isolated micro grid and the batteries used to store energy. There are basically two states in which the system will work. One of the states is when there is enough wind power to supply the loads and the extra energy is used to charge the batteries. The other state is when there is low wind power and the batteries have to compensate the lack of power, so that the isolated micro grid has enough power to supply at least the priority loads. In this paper are presented the hardware and the control algorithm for the developed system. The topology was previously tested in computer simulations, using the software PSIM 9.0, and then validated with the implementation of a laboratory prototype.