Air quality in Oporto área: comparative analysis

A partir de 1986-1987, on observe une tendance irrégulière de l'augmentation des concentrations moyennes mensuelles d'acidité forte et fumées noires. Les concentrations correspondant aux jours de la semaine sont supérieures à celles obtenues les week-ends et jours fériés, lesquelles mettent en évidence l'apport de l'activité industrielle et du trafic. Aucune corrélation mathématique significative traduisant l'évolution croissante des concentrations moyennes annuelles n'a été mise en évidence. Dans les stations les plus représentatives, les valeurs guides ont été dépassées, les concentrations étant proches de la limite. Bien que nous n'ayons pas enregistré d'épisodes aigus de pollution, l'évolution vérifiée durant la période prise en compte traduit un aggravement de la qualité de l'air. Cette tendance à la hausse est contraire à celle observée dans d'autres pays, où les niveaux d'acidité forte et fumées noires tendent à baisser grâce aux mesures de protection de l'environnement mises en pratique. Les niveaux de monoxyde de carbone, d'oxydes d'azote et d'ozone, observés en 1992 sont plus bas que dans d'autres régions.It was recorded an irregular trend upward for strong acidity and black smoke average monthly concentrations since 1986-1987. Levels in the working days are higher than those monitored in the week-end and days off, which proves the effect of traffic and industrial activities on air quality. It was not possible to establish any overall correlation fiable to express the increase in annual average concentrations. At the most representative stations, the exceedance of guideline values was recorded and concentrations reached values close to the limit. No acute episodes of air pollution were recorded, although the trend patterns monitored show an aggravation of air quality during this period of time. This trend is contrary to the one derived in foreign networks, where strong acidity and black smoke levels have been decreasing in consequence of environmental protection measures put into practice. Carbon monoxyde, nitrogen oxydes and ozone levels measured in 1992 are lower when compared with those monitored in other regions

Viabilidade de implantacao de aveia em pastagens estabelecidas de capim-elefante.

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Simplification of State Transition Diagrams in Average Unavailability Analysis by Using Generalized Perturbation Theory

Safety analysis studies in nuclear engineering, more specifically system reliability, usually handle a great number of components, so that computational difficulties may arise. To face the problem of many component systems a method for simplifying the state transition diagram in Markovian reliability analyses has been proposed, using the edges which can be cut, since these latter have a smaller influence on system failure probability. In order to extend the application of GPT (Generalized Perturbation Theory), this work uses GPT formalism to reduce the number of states in a transition diagram, not considering the state probability as the integral quantity of interest, but the mean system unavailability instead. Therefore, after simplifying the original diagram, the mean unavailability for the new system was calculated and the results were very close to those of the original diagram integral quantity (giving a relative error of about 2%), showing that the proposed simplification is quite reasonable and simple to apply

Generalized differential privacy: regions of priors that admit robust optimal mechanisms

International audienceDifferential privacy is a notion of privacy that was initially designed for statistical databases, and has been recently extended to a more general class of domains. Both differential privacy and its generalized version can be achieved by adding random noise to the reported data. Thus, privacy is obtained at the cost of reducing the data's accuracy, and therefore their utility. In this paper we consider the problem of identifying optimal mechanisms for gen- eralized differential privacy, i.e. mechanisms that maximize the utility for a given level of privacy. The utility usually depends on a prior distribution of the data, and naturally it would be desirable to design mechanisms that are universally optimal, i.e., optimal for all priors. However it is already known that such mechanisms do not exist in general. We then characterize maximal classes of priors for which a mechanism which is optimal for all the priors of the class does exist. We show that such classes can be defined as convex polytopes in the priors space. As an application, we consider the problem of privacy that arises when using, for instance, location-based services, and we show how to define mechanisms that maximize the quality of service while preserving the desired level of geo- indistinguishability

Sustainability improvement of a composite materials' industry through recycling re-engineering process approaches

This case study was aimed at measuring and assessing the potential improvements that couldbe made on the eco-efficiency performance of a composite materials' industry, specifically aglass fibre reinforced plastic (GFRP) pultrusion manufacturing company. For this purpose, allthe issues involved in the pultrusion process of GFRP profiles were analysed, the current ecoefficiency performance of the company was determined, all the procedures applied in theproduction process were revised, and improvement strategies were planned and investigatedwith basis on the performed analysis. The new eco-efficiency ratios were estimated takinginto account the implementation of new proceedings and procedures through re-engineeringthe manufacturing process and recycling approaches. These features lead to significantimprovements on the sequent assessed eco-efficiency ratios, yielding to a more sustainableproduct and manufacturing process of pultruded GFRP profiles

Challenging differential privacy: the case of non-interactive mechanisms

Best Student Paper AwardInternational audienceIn this paper, we consider personalized recommendation systems in which before publication, the profile of a user is sanitized by a non-interactive mechanism compliant with the concept of differential privacy. We consider two existing schemes offering a differentially private representation of profiles: BLIP (BLoom-and-flIP) and JLT (Johnson-Lindenstrauss Transform). For assessing their security levels, we play the role of an adversary aiming at reconstructing a user profile. We compare two inference attacks named single and joint decoding. The first one decides of the presence of a single item in the profile, and sequentially browses all the item set. The latter strategy decides whether a subset of items is likely to be the user profile, and browses all the possible subsets. Our contributions are a theoretical analysis and practical implementations of both attacks tested on datasets composed of real user profiles revealing that joint decoding is the most powerful attack. This also gives useful insights on the setting the differential privacy parameter $\epsilon$

Altura da planta e cobertura do solo como estimadores da produção de forragem em pastagem de capim-elefante.

O objetivo deste estudo foi determinar a extensão em que a altura da planta e da cobertura do solo poderia ser usada como indicador da produção de pastagem em capim-elefante, sob pastejo. Amostras da produção de pastagem, altura da planta e cobertura do solo foram realizadas em pastagem de capim-elefante (Pennisetum purpureum Schum.) durante os anos de 1992, 1993 e 1994. Foram usadas 30, 72 e 72 amostras para cada ano de avaliação, respectivamente. Os dados da produção de matéria seca foram submetidos à análise de regressão, em função da altura da planta e da cobertura do solo, usando vários modelos. O modelo linear foi o que apresentou o melhor ajuste dos dados, tanto para cobertura do solo quanto para o índice altura da planta vs cobertura do solo. As melhores estimativas da produção de matéria seca foram obtidas quando se combinaram medidas de altura da planta com as de cobertura do solo, analisadas por meio de regressão múltipla. Estas regressões revelaram valores de R2 mais elevados, indicando que a altura da planta e a cobertura do solo podem ser consideradas características complementares, como estimadores da produção de matéria seca em pastagem de capim-elefante

Resposta do coast-cross (Cynodon dactylon (L.) Pers.) a diferentes doses de nitrogênio e intervalos de cortes.

Este experimento foi realizado para avaliar os efeitos de quatro doses de nitrogênio (0, 250, 500 e 750 kg/(ha-ano) e seis intervalos de cortes do capim coast-cross (2, 3, 4, 5, 6 e 7 semanas, na época das chuvas, e 4, 5, 6, 7, 8 e 9 semanas, na época da seca). A adubação potássica consistiu da relação K2O/N igual a 0,8. Anualmente, foram aplicados 80 kg/ha de P2O5 . Os cortes foram realizados a 5 - 7 cm acima do nível do solo. Na época da seca, toda a área experimental foi irrigada. O delineamento experimental usado foi o de blocos ao acaso, em esquema de parcelas subdivididas e três repetições. No geral, as produções anuais e estacionais de matéria seca aumentaram com os intervalos de cortes (compotamento linear) e com as doses de nitrogênio até 500 kg/(ha?ano) (comportamento quadrático), atingindo a produção de 30,8 t/ha-ano. A dose de nitrogênio associada a 90% da produção anual máxima (26,4 t/[ha?ano] de matéria seca), nos intervalos de cortes de seis semanas, nas chuvas, e oito semanas, na seca, foi de 583 kg/(ha?ano). O teor de proteína bruta aumentou com a elevação na dose de nitrogênio aplicada e com a redução do intervalo de cortes, adequando-se ao modelo de regressão linear, tendo atingido teor máximo de 23,4%. Dependendo do intervalo de cortes, a persistência do coast-cross foi comprometida na ausência da adubação nitrogenada ou quando foram aplicados 250 kg/ha de nitrogênio