Amâncio Carvalho

A soft-switching DC/DC converter to improve performance of a PEM fuel cell system

This paper presents a soft-switching dc/dc converter with ZCS to improve the performance of a PEM fuel cell as a power generation system. The first part of the paper presents an appropriate model for the fuel cell behavior based on analytical formulation of chemical processes behind fuel cell operation and the design of an equivalent and analogue electrical circuit describing the fuel cell operation. A method to extract the set of parameters needed for modeling and to optimize their values is also presented. For the validation of this approach experimental tests are performed with a commercial fuel cell system. The dynamics of the fuel cell model and the dependency on operation point are analyzed. In fact, the dynamics of the fuel cell must be taken in account for an accurate characterization of the fuel cell as a power generation unit. As a power generation unit the fuel cell must be integrated with a dc/dc converter able of controlling the system operating as a dc regulated Voltage source and controlling the fuel cell MPPT, maximizing the generated energy. Authors purpose in the second part of the paper a topology this dc/dc converter based on resonant operation, which allows a soft-switching commutation, and consequently a high efficiency operation. Analysis on selected topology choice, the control and design of the converter are performed. Carried out results show that the controller needs to have a dynamic derivative component in order to ensure a good regulation of output voltage for different load conditions and disturbances on them. The overall system is validated using Matlab/Simulink models.

DYNAMIC MODELING AND SIMULATION OF AN OPTIMIZED PROTON EXCHANGE MEMBRANE FUEL CELL SYSTEM

Hydrogen and fuel cells are widely regarded as the key to energy solutions for the 21st century. These technologies will contribute significantly to a reduction in environmental impact, enhanced energy security and development of new energy industries. Fuel cells operating with hydrogen have the potential to contribute to the transition for a future sustainable energy system with low-CO2 emissions. In this paper a dynamic PEM fuel cell model, implemented in Matlab/Simulink, is presented. In order to estimate the PEM fuel cell model parameters, an optimization based approach is used. The optimization is carried out using the Simulated Annealing (SA) algorithm. This optimization process evolves converging to a minimum of the objective function. The flexibility and robustness of SA as a global search method are extremely important advantages of this method. A good agreement between experimental and simulated results is observed. This optimized PEM fuel cell model can significantly help designers of fuel cell systems by providing a tool to perform accurate design and consequently to improve system efficiency.Copyright

In-motion wireless power transfer: Technology, infrastructure, challenges and market scenario

In-motion Wireless Power Transfer (IM-WPT) is the ability of charging the battery of an EV while it is in motion. This paper introduces a review of IM-WPT charging. The main issuses relatted to; the technology associated, infrastructure and current challenges faced in research and the market scenario are addressed along the paper.

Percepção sobre o apoio social do homem colostomizado na região Norte de Portugal

Objective: To evaluate the perceptions of colostomized men concerning the social support received and to verify the relationship between perceived social support and socio-demographic variables, the information provided, the support they actually received, and educational sessions at the hospital. Methods: This is a descriptive-correlational, cross-sectional study, a quantitative approach with a sample of 112 men who had a colostomy for over a year, in three health units of northern Portugal. Results: The average age of participants was 59.9 years, 67.9% were inactive in terms of work, 49.5% perceive support as sufficient, insufficient support 36.2% and 14.3% neutral support. The perception of support is lower in older subjects (r = -0.166; p = 0.018). Conclusion: This study showed that the spouse is very important in the life of a colostomised man, particularly in times of difficulties inherent to the disease, representing his main support network.

Efeito da formação nas concepções de saúde e de Promoção da Saúde de estudantes do ensino superior

Resumo Introducao As concepcoes dos alunos sao muito complexas e dependem da historia de vida de cada pessoa, da sua cultura e das suas representacoes sociais, sendo funcao dos conhecimentos, dos sistemas de valores e das praticas sociais 1 . Por sua vez, as praticas de Educacao para a Saude expressam as concepcoes de quem as desenvolve e sao por elas influenciadas. Daqui se conclui que as concepcoes de saude e Promocao da Saude/Educacao para a Saude sao muito importantes. Material e metodos Assim, o objectivo geral do presente estudo foi de comparar o sistema de valores em promocao e educacao para a saude veiculados em cursos na area da saude, ensino pre-escolar, ensino basico e servico social, a fim de compreender a relacao entre as concepcoes a ensinar e as concepcoes ensinadas. Para tal desenvolvemos um estudo descritivo, comparativo e transversal, cuja amostra foi constituida por 709 alunos (63% do universo dos alunos) de sete cursos do ensino superior, sendo quatro cursos no âmbito da saude (Medicina, Enfermagem de Braga, do Porto e de Vila Real), dois no âmbito da educacao (Educadores de Infância e Professores do 1° Ciclo do Ensino Basico) e um no âmbito do Servico Social. Aplicou-se um questionario de auto-preenchimento aos alunos do 1° e do 4° ano dos referidos cursos. Resultados As cinco palavras-chave mais utilizadas pelo total da amostra para referir o conceito de saude foram as seguintes (por ordem decrescente): “Bem-estar”, “Hospital”, “Doenca”, “Medicos” e “Enfermeiros”, tendo a primeira sido utilizada por 77,4% dos alunos. A predominância destas palavras-chave podera estar ligada a uma visao reducionista dos determinantes de saude, centrada nas unidades de saude, deixando de fora os outros determinantes de saude. Foi no curso de Enfermagem de Braga (E-BR) que se verificaram mais descidas das palavras-chave ligadas a visao reducionista do termo Saude, entre o 1° e o 4° ano; da mesma forma, o curso de Professores do Ensino Basico (PEB) foi aquele que mostrou mais aumentos ligados ao conceito abrangente da Saude, entre o 1° e o 4° ano. Pelo contrario, no curso de E-VR, nao se notaram alteracoes significativas na perspectiva de Saude entre o 1° e o 4° ano, tendo ambos uma visao tecnico-centrica da saude. Do total da amostra, 86% dos alunos atribuem mais importância a perspectiva positiva de Saude, 91% e 65% elegem a perspectiva abrangente, respectivamente, de Saude Escolar e de Promocao da Saude. A maioria dos alunos considera que os termos Promocao da Saude e Educacao para a Saude sao diferentes, embora nao os consigam distinguir verbalmente. Conclusoes Dos resultados obtidos emergiu um conjunto de conclusoes e recomendacoes que constituem o desfecho do presente artigo.

Quality of life of ostomized person: relationship with the care provided in stomatherapy nursing consultation

Objective: To analyze the relationship between the Quality of Life (QoL) and the stomatherapy nursing consultation. Method: Descriptive-correlational study with 100 ostomized adult participants, to whom a form was applied. The data were treated with SPSS software version 20.0. Results: Most ostomized (67%) presented a positive perception of QoL. This differed significantly (p < 0.05) between the types of ostomy and previous preparation in the consultation, as the colostomy patients and the individuals who booked the appointment of the stoma previously during the consultation had a better QoL. Conclusions: There is a statistical relationship between QoL, the type of ostomy and the participation in the stomatherapy nursing consultation, demonstrating the positive influence of nursing care for the ostomized. The study reinforces the importance of consultation for the adaptation of ostomized people to the new condition and improvement of their QoL.

Linux- and FPGA-based accelerated single-phase shunt active power filter

This paper focuses on the challenges faced when developing modern power electronic converters towards the concept of tomorrows smart grids. Industrial and commercial electronic devices are nonlinear loads by nature and so they absorb non-sinusoidal currents and usually a chump of reactive energy. The presence of such loads raises power quality problems at installation sites as well as in the distribution system. Research has been focused on the electronic converters to improve electrical waveform quality, in particular, on shunt active power filters which are suitable to compensate current harmonics. In this paper, a shunt active power filter with an integrated Hardware/Software Digital Controller based on the p-q Power Theory is presented. A state-of-the-art embedded digital controller was deployed on Linux leveraging design re-use, implementation portability, scalability as well as designer flexibility. To tackle the performance limitations, to increase system determinism and the overall latency time of the controller, the operating system overhead was minimized by (1) offloading critical software components of the controller to FPGA, (2) minimizing user- and kernel-space memory crossings to a minimum, and (3) exploring FPGA-based platforms and their communication interfaces, to promote high speed control and communication concurrency.

Qualidade de vida dos utentes dos cuidados de saúde primários do distrito de Vila Real

Theoretical framework: The Quality of Life (QoL) is determined by functional status and health condition, depending largely on individual, socio-economic a...

Perceptions of the social support for colostomized men in northern Portugal

Objective: To evaluate the perceptions of colostomized men concerning the social support received and to verify the relationship between perceived social support and socio-demographic variables, the information provided, the support they actually received, and educational sessions at the hospital. Methods: This is a descriptive-correlational, cross-sectional study, a quantitative approach with a sample of 112 men who had a colostomy for over a year, in three health units of northern Portugal. Results: The average age of participants was 59.9 years, 67.9% were inactive in terms of work, 49.5% perceive support as sufficient, insufficient support 36.2% and 14.3% neutral support. The perception of support is lower in older subjects (r = -0.166; p = 0.018). Conclusion: This study showed that the spouse is very important in the life of a colostomised man, particularly in times of difficulties inherent to the disease, representing his main support network.

La percepción del apoyo social del hombre con colostomía en la región Norte de Portugal

Objective: To evaluate the perceptions of colostomized men concerning the social support received and to verify the relationship between perceived social support and socio-demographic variables, the information provided, the support they actually received, and educational sessions at the hospital. Methods: This is a descriptive-correlational, cross-sectional study, a quantitative approach with a sample of 112 men who had a colostomy for over a year, in three health units of northern Portugal. Results: The average age of participants was 59.9 years, 67.9% were inactive in terms of work, 49.5% perceive support as sufficient, insufficient support 36.2% and 14.3% neutral support. The perception of support is lower in older subjects (r = -0.166; p = 0.018). Conclusion: This study showed that the spouse is very important in the life of a colostomised man, particularly in times of difficulties inherent to the disease, representing his main support network.