Control of Structure in Conventional Friction Stir Welds through a Kinematic Theory of Metal Flow

In friction stir welding (FSW), a rotating pin is translated along a weld seam so as to stir the sides of the seam together. Metal is prevented from flowing up the pin, which would result in plowing/cutting instead of welding, by a shoulder on the pin. In conventional FSW, the weld metal rests on an "anvil", which supports the heavy "plunge" load on the tool. In this study, both embedded tungsten wires along and copper plating on the faying surfaces were used to trace the flow of AA2219 weld metal around the C-FSW tool. The effect of tool rotational speed, travel speed, plunge load, and pin thread pitch on the resulting weld metal flow was evaluated. Plan, longitudinal, and transverse section x-ray radiographs were examined to trace the metal flow paths. The results are interpreted in terms of a kinematic theory of metal flow in FSW

INFLUENCE OF CELL WALL CALCIUM CONTENT IN FRUIT FIRMNESS DURING THE RIPENING OF PLUMS (PRUNUS DOMESTICA L.).

‘Rainha Claudia Verde’ is a regional cultivar of Prunus domestica L. well adapted to a specific region in the south of Portugal. In order to understand the postharvest behavior of this cultivar produced in different orchards, cell wall poly-saccharides and cell wall calcium fruit content were studied during ripening in two consecutive years. During harvest period pectic fractions soluble in water, carbonate and KOH were prepared from alcohol-insoluble residue (AIR) of plums. Galacturonic and neutral sugars contents were measured during fruit ripening and fruit firmness was also evaluated. The calcium fruit level was determined in the AIR during harvest season as well as in dry matter. Fruit firmness was significantly higher in the second year and was probably related with calcium fruit content and pectic polysaccharides. There was a significant difference in calcium fruit content between orchards, and this might influence the overall fruit texture during the postharvest period. During fruit ripening water soluble pectic polysaccharides did not change significantly, which corresponded with the small decrease in tissue firmness. The occurrence in the supernatant of the cellulosic residue of highly branched polysaccharides might be the consequence of matrix material associated with microfibrilar phase. Depolymerization of the hemicellulosic fraction was not evident during plum ripening. The loss of fruit firmness is a consequence of many cellular events which are influenced by external factors. The knowledge of calcium content in the cell wall and the pectic poly¬saccharides could be of great importance to local farmers to predict fruit texture

Green space influence on thermal confort: structured studies in the city of Bragança (Portugal)

Green Spaces are regarded as elements that can provide thermal comfort in cities. A research on green spaces contribution to thermal comfort was carried out, with the purpose of identifying essential principles that can help urban designers to enhance the social use of open spaces. These studies were developed in summer and early fall conditions, by means of structured experiments. These experiments took place in three occasions between June 2008 and September 2009, in a total of 432 thermal sensations questionnaires. The methodology consisted in placing different individuals, organized in uniform age groups and equal numbered in gender, under different thermal environments (shadow versus sun exposure, wind versus wind shield, grass versus artificial pavement) and asking them to express their thermal sensations (using a seven levels scale), while collecting meteorological data. A multinomial logistic regression was used to study the influence of both meteorological variables and personal attributes in thermal sensations. Significant results were found relating differences in thermal comfort with the radiation, air temperature and wind speed. Gender was also found to have a significant influence in human thermal sensations. Results show that differences in green spaces layout can significantly change the thermal environment, thus influencing thermal perceptions

Benefits of urban green spaces in noise, air quality and thermal comfort: the case study of Bragança

Urban green areas provide multiple environmental services, contributing to high‐quality environments in our cities. With the purpose of evaluating the influence of urban green spaces in air quality, noise and thermal comfort, a research was developed throughout the last 4 years in the city of Bragança, Portugal. All these aspects were approached from physical and social perspectives. The physical approach involved several studies at urban and green space scales. Field experiments covered such areas as measurements of air pollutants concentrations (ozone, nitrogen dioxide, volatile organic compounds and PM10), sound pressure levels, meteorological and other parameters related to thermal comfort. The social approach consisted in assessing perceptions of citizens over green spaces and their influence on the environment, alongside with the assessment of their attitudes towards those spaces, by means of specific questionnaires applied to a representative sample of local inhabitants. Results showed the relevance of the green spaces in contributing to ameliorate air quality, create more pleasant soundscapes and provide better thermal comfort conditions, especially in spring and summer. Relations between benefits of green spaces and their size, their physical and biological diversity, and their location were found. These characteristics were also identified by respondents as key factors in a moment of selecting a green space to pass the time and to enjoy part or all services it can provide. In the opinion of the respondents, those factors are crucial in maximizing many environmental and social functions of urban green spaces

Green space influence on thermal comfort contrasting approaches in the assessment of conditions in Bragança (Portugal)

Green Spaces are regarded as elements that can help to provide thermal comfort inside cities. To evaluate this influence both climate and personal variables must be investigated and evaluated taking into account different spatial layouts. Trying to address this complex reality, two different approaches were developed, using green spaces at the city of Bragança (Portugal) as case studies: green spaces surveys, addressing users, and structured experiments, controlling both individual and climatic variables. Field surveys proven to identify a narrow range of thermal sensations, thus limiting the analysis. Data from a structured experiment, conducted in early fall conditions, show the influence of different green space locations on both meteorological variables and thermal sensations. Amongst the evaluated variables, global radiation proves to be the most relevant variable influencing the perceived thermal sensations.POCTI - FC

Influence of green spaces on outdoors thermal comfort-structured experiment in a Mediterranean climate

As a growing part of the global population lives in cities, green spaces are an essential asset for improving quality of life. This study aims to address the role of green spaces in providing favorable thermal comfort conditions for the use of outdoor spaces. The research methodology consisted of a structured experiment where a defined set of individuals from different age groups was exposed to differentiated microclimate conditions. Four nearby locations were considered, ranging from a stone-paved surface without shade to high tree canopy coverage over grass. This experiment took place in three different days in summer and early autumn conditions, with a total of 432 questionnaires. Results show a wide range of thermal sensations found during this experiment, while more favorable thermal sensations were found in shaded locations. To investigate the role of prevailing meteorological and personal conditions on thermal sensations, multinomial logistic regression analysis was applied. Results show the influence of air temperature, global radiation, wind speed, and interviewees’ gender. As meteorological variables were influenced by the diverse contexts found within a close distance inside the studied green space, results from this structured experiment suggest the need for micrometeorological diversity in the local context as a means to promote greater adaptive opportunities for green spaces users.Meteorological equipment acquisition was funded by the National Scientific Foundation of Portugal (FCT) given to project GreenUrbe POCI/AMB/59174/2004.info:eu-repo/semantics/publishedVersio

Green space influence on thermal comfort: contrasting approaches in the assessment of conditions in Bragança (Portugal)

Urban greening has been widely recognised as a key factor to mitigate the adverse effects of urbanisation in a sustainable manner [1]. Green spaces characteristics include trees, soft surfaces and wind shelters that can influence thermal sensations by inducing changes in such variables as solar radiation, temperatures of surrounding surfaces, air temperature, humidity and wind speed [2,3]. As part of the ongoing research entitled GreenUrbe (PPCDT/AMB/59174/2004), both users surveys and structured experiments are being developed, trying to establish relation between green spaces characteristics and thermal comfort. The city of Bragança is located in north-eastern Portugal. Local climate is characterised by a cold rainy winter and relatively short (June to September) hot and dry summer.FCT-MCTE

Avaliação da influência dos espaços verdes

A presente comunicação é parte integrante do Projecto POCI/AMB/59174/2004 – Impacte dos Espaços Verdes na Qualidade do Ambiente Urbano, contribuindo ainda para as definições do Plano Verde da Cidade de Bragança. Durante o Verão de 2006 foram conduzidas experiências de avaliação da influência dos espaços verdes no conforto térmico, baseadas nos estudos desenvolvidos por Givoni et al. (2003), com o objectivo de testar as reacções de diversos indivíduos ao conforto climático em situações contrastantesFCT-MCTE

O papel da vegetação urbana no controlo das concentrações de PM10

O aumento dos níveis de PM10 em atmosferas urbanas constitui um grave problema de saúde pública. A utilização de vegetação pode ser uma forma sustentável de mitigar este problema. Neste contexto, foi desenvolvido um estudo, na cidade de Bragança, com vista a avaliar o papel da vegetação no controlo das concentrações de PM10. Este estudo assentou em dois tipos de experiências. Uma que consistiu na medição de PM10 em dois transectos com características contrastantes, em termos de coberto vegetal, traçados numa cintura verde urbana. O outro tipo de experiência consistiu na utilização de uma fonte de material particulado, seguindo-se a medição dos níveis de PM10 ao longo de um transecto linear que cortava perpendicularmente uma sebe. Os resultados mostram que a vegetação tende a criar atmosferas ligeiramente mais limpas em PM10 e revelam igualmente que uma sebe de pyracantha actua eficazmente na filtração de partículas

Solid catalysts obtained from wastes for FAME production using mixtures of refined palm oil and waste cooking oils

More than 95% of biodiesel production feedstocks come from edible oils, however it may cause some problems such as the competition of land use between food production and biodiesel production. The waste cooking oils (WCO) are an alternative feedstock for biodiesel production; its usage reduces significantly the cost of biodiesel production and has environmental benefits, e.g., a waste recovery instead of its elimination. This work aims to produce a low-cost efficient solid catalyst for fatty acid methyl esters (FAME) production using mixtures of refined palm oil (RPO) and WCO. Four low cost catalysts were prepared (biomass fly ashes, natural dolomite rock, chicken eggshells and polyethylene terephthalate - PET), characterized (by SEM, EDX, XRD, BET, FT-IR and Hammett indicators) and tested regarding their performance in FAME production. The maximum yield of FAME achieved was around 96%wt. for biomass fly ashes catalyst at 60 °C, 9:1 (mol/mol) of methanol to oil mixture, 10%wt. catalyst to oil mixture, over 180 min in batch reactor. The results point out for promising bifunctional catalysts able to achieve also conversion of free fatty acids up to 100% using mixtures of RPO and WCO.publishe