Análise de métodos para detecção de mudanças estruturais em séries temporais climáticas

The time series analysis has played an increasingly important role in weather and climate studies. The success of these studies depends crucially on the knowledge of the quality of climate data such as, for instance, air temperature and rainfall data. For this reason, one of the main challenges for the researchers in this field is to obtain homogeneous series. A time series of climate data is considered homogeneous when the values of the observed data can change only due to climatic factors, i.e., without any interference from external non-climatic factors. Such non-climatic factors may produce undesirable effects in the time series, as unrealistic homogeneity breaks, trends and jumps. In the present work it was investigated climatic time series for the city of Natal, RN, namely air temperature and rainfall time series, for the period spanning from 1961 to 2012. The main purpose was to carry out an analysis in order to check the occurrence of homogeneity breaks or trends in the series under investigation. To this purpose, it was applied some basic statistical procedures, such as normality and independence tests. The occurrence of trends was investigated by linear regression analysis, as well as by the Spearman and Mann-Kendall tests. The homogeneity was investigated by the SNHT, as well as by the Easterling-Peterson and Mann-Whitney-Pettit tests. Analyzes with respect to normality showed divergence in their results. The von Neumann ratio test showed that in the case of the air temperature series the data are not independent and identically distributed (iid), whereas for the rainfall series the data are iid. According to the applied testings, both series display trends. The mean air temperature series displays an increasing trend, whereas the rainfall series shows an decreasing trend. Finally, the homogeneity tests revealed that all series under investigations present inhomogeneities, although they breaks depend on the applied test. In summary, the results showed that the chosen techniques may be applied in order to verify how well the studied time series are characterized. Therefore, these results should be used as a guide for further investigations about the statistical climatology of Natal or even of any other place.

Influência das condições ambientais no verdor da vegetação da caatinga frente às mudanças climáticas

The Caatinga biome, a semi-arid climate ecosystem found in northeast Brazil, presents low rainfall regime and strong seasonality. It has the most alarming climate change projections within the country, with air temperature rising and rainfall reduction with stronger trends than the global average predictions. Climate change can present detrimental results in this biome, reducing vegetation cover and changing its distribution, as well as altering all ecosystem functioning and finally influencing species diversity. In this context, the purpose of this study is to model the environmental conditions (rainfall and temperature) that influence the Caatinga biome productivity and to predict the consequences of environmental conditions in the vegetation dynamics under future climate change scenarios. Enhanced Vegetation Index (EVI) was used to estimate vegetation greenness (presence and density) in the area. Considering the strong spatial and temporal autocorrelation as well as the heterogeneity of the data, various GLS models were developed and compared to obtain the best model that would reflect rainfall and temperature influence on vegetation greenness. Applying new climate change scenarios in the model, environmental determinants modification, rainfall and temperature, negatively influenced vegetation greenness in the Caatinga biome. This model was used to create potential vegetation maps for current and future of Caatinga cover considering 20% decrease in precipitation and 1 °C increase in temperature until 2040, 35% decrease in precipitation and 2.5 °C increase in temperature in the period 2041-2070 and 50% decrease in precipitation and 4.5 °C increase in temperature in the period 2071-2100. The results suggest that the ecosystem functioning will be affected on the future scenario of climate change with a decrease of 5.9% of the vegetation greenness until 2040, 14.2% until 2070 and 24.3% by the end of the century. The Caatinga vegetation in lower altitude areas (most of the biome) will be more affected by climatic changes.

Cálculo das incertezas climáticas sobre América do Sul utilizando modelos do CMIP5: aferição através das redes neurais artificiais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Criação de zonas de alta permeabilidade em fraturas: modelagem numérica do Lajedo de Soledade, Formação Jandaíra, Bacia Potiguar

The fracturing in carbonate rocks has been attracting increasingly attention due to new oil discoveries in carbonate reservoirs. This study investigates how the fractures (faults and joints) behave when subjected to different stress fields and how their behavior may be associated with the generation of karst and consequently to increased secondary porosity in these rocks. In this study I used satellite imagery and unmanned aerial vehicle UAV images and field data to identify and map faults and joints in a carbonate outcrop, which I consider a good analogue of carbonate reservoir. The outcrop comprises rocks of the Jandaíra Formation, Potiguar Basin. Field data were modeled using the TECTOS software, which uses finite element analysis for 2D fracture modeling. I identified three sets of fractures were identified: NS, EW and NW-SE. They correspond to faults that reactivate joint sets. The Ratio of Failure by Stress (RFS) represents stress concentration and how close the rock is to failure and reach the Mohr-Coulomb envelopment. The results indicate that the tectonic stresses are concentrated in preferred structural zones, which are ideal places for carbonate dissolution. Dissolution was observed along sedimentary bedding and fractures throughout the outcrop. However, I observed that the highest values of RFS occur in fracture intersections and terminations. These are site of karst concentration. I finally suggest that there is a relationship between stress concentration and location of karst dissolution in carbonate rocks.

Criação de zonas de alta permeabilidade em fraturas: modelagem numérica do Lajedo de Soledade, Formação Jandaíra, Bacia Potiguar

The fracturing in carbonate rocks has been attracting increasingly attention due to new oil discoveries in carbonate reservoirs. This study investigates how the fractures (faults and joints) behave when subjected to different stress fields and how their behavior may be associated with the generation of karst and consequently to increased secondary porosity in these rocks. In this study I used satellite imagery and unmanned aerial vehicle UAV images and field data to identify and map faults and joints in a carbonate outcrop, which I consider a good analogue of carbonate reservoir. The outcrop comprises rocks of the Jandaíra Formation, Potiguar Basin. Field data were modeled using the TECTOS software, which uses finite element analysis for 2D fracture modeling. I identified three sets of fractures were identified: NS, EW and NW-SE. They correspond to faults that reactivate joint sets. The Ratio of Failure by Stress (RFS) represents stress concentration and how close the rock is to failure and reach the Mohr-Coulomb envelopment. The results indicate that the tectonic stresses are concentrated in preferred structural zones, which are ideal places for carbonate dissolution. Dissolution was observed along sedimentary bedding and fractures throughout the outcrop. However, I observed that the highest values of RFS occur in fracture intersections and terminations. These are site of karst concentration. I finally suggest that there is a relationship between stress concentration and location of karst dissolution in carbonate rocks.

Determinação de recomendações bioclimáticas para habitação de interesse social de quatro climas do Rio Grande do Norte

Recomendações projetuais baseadas no clima são fontes importantes de diretrizes para os arquitetos. Uma das formas de obtenção dessas recomendações é por meio de normas, como a NBR 15220 (ABNT, 2005), que agrupa as cidades em zonas homogêneas quanto as estratégias sugeridas. O zoneamento bioclimático brasileiro divide o território do Rio Grande do Norte em duas zonas, a ZB 7 e ZB 8, que possuem algumas recomendações distintas, como aberturas grandes e vedações leves para a região litorânea contra aberturas pequenas e vedações pesadas para a região semiárida. Entretanto, outras configurações climáticas estão presentes no RN e não possuem clara recomendação. Este é o caso das regiões serranas e das regiões intermediárias entre o litoral e a região semiárida. Em virtude disso, este estudo visa encontrar recomendações bioclimáticas para habitações de interesse social nessas quatro condições climáticas. Para tanto, utilizou-se ferramenta computacional para realização de simulações das condições térmicas de três tipos de habitações populares - alongada, ramificada e compacta - e das seguintes estratégias: presença ou ausência de ventilação natural e sombreamento, massa térmica leve ou pesada, e Fator de Calor Solar alto ou baixo. Essas simulações foram realizadas para quatro condições climáticas do estado. Foram analisados os desempenhos de cada caso para identificar as estratégias e tipos de habitação recomendados para cada clima. De maneira geral, nos climas deNatal, Mossoró e Caicó viu-se que habitações com FCS baixo e com presença de ventilação natural possuem os melhores desempenhos. No clima de Areia, a ausência de ventilação aliada ao baixo FCS é que produziu os melhores desempenhos. O sombreamento melhora o desempenho nas cidades de clima quente, mas aumenta as horas com desconforto ao frio em Areia. A massa térmica varia de acordo com as demais estratégias, tendo casos em que habitações com massa térmica alta possuem melhores desempenhos que outros casos com massa térmica baixa. Por fim, viu-se que as estratégias para Natal, Caicó e Mossoró são bem semelhantes, com a recomendação de ventilação natural, FCS baixo nas vedações e sombreamento. Para Areia, a recomendação é não ventilar, ter FCS baixo e massa térmica alta.

Determinação de recomendações bioclimáticas para habitação de interesse social de quatro climas do Rio Grande do Norte

Recomendações projetuais baseadas no clima são fontes importantes de diretrizes para os arquitetos. Uma das formas de obtenção dessas recomendações é por meio de normas, como a NBR 15220 (ABNT, 2005), que agrupa as cidades em zonas homogêneas quanto as estratégias sugeridas. O zoneamento bioclimático brasileiro divide o território do Rio Grande do Norte em duas zonas, a ZB 7 e ZB 8, que possuem algumas recomendações distintas, como aberturas grandes e vedações leves para a região litorânea contra aberturas pequenas e vedações pesadas para a região semiárida. Entretanto, outras configurações climáticas estão presentes no RN e não possuem clara recomendação. Este é o caso das regiões serranas e das regiões intermediárias entre o litoral e a região semiárida. Em virtude disso, este estudo visa encontrar recomendações bioclimáticas para habitações de interesse social nessas quatro condições climáticas. Para tanto, utilizou-se ferramenta computacional para realização de simulações das condições térmicas de três tipos de habitações populares - alongada, ramificada e compacta - e das seguintes estratégias: presença ou ausência de ventilação natural e sombreamento, massa térmica leve ou pesada, e Fator de Calor Solar alto ou baixo. Essas simulações foram realizadas para quatro condições climáticas do estado. Foram analisados os desempenhos de cada caso para identificar as estratégias e tipos de habitação recomendados para cada clima. De maneira geral, nos climas deNatal, Mossoró e Caicó viu-se que habitações com FCS baixo e com presença de ventilação natural possuem os melhores desempenhos. No clima de Areia, a ausência de ventilação aliada ao baixo FCS é que produziu os melhores desempenhos. O sombreamento melhora o desempenho nas cidades de clima quente, mas aumenta as horas com desconforto ao frio em Areia. A massa térmica varia de acordo com as demais estratégias, tendo casos em que habitações com massa térmica alta possuem melhores desempenhos que outros casos com massa térmica baixa. Por fim, viu-se que as estratégias para Natal, Caicó e Mossoró são bem semelhantes, com a recomendação de ventilação natural, FCS baixo nas vedações e sombreamento. Para Areia, a recomendação é não ventilar, ter FCS baixo e massa térmica alta.

Análise bioclimática como ferramenta para implementação do plano diretor do campus central da UFRN

This research investigates the microclimate and the morphology features of the central campus of the UFRN, in Natal-RN, through the use of bioclimatic tools of analysis in order to assist the implementation of the campus´ Master Plan. It develops a diagnosis of the evolution and growth of the urban space surveyed by analyzing its initial plan and the basic urban conception behind it, as well as the morphology and typologies utilized. The study makes a qualitative analysis of the local microclimate by using Katzschner (1997) methodology, with land-use and topography maps, building heights, vegetation and soil covering. It also makes use of the methodology proposed by Oliveira (1993), which examines, from the bioclimatic standpoint, the human environment as related to the urban form (site and built mass). It identifies zones whose climatic characteristics are representative of the local microclimate and classifies them into areas to be strictly preserved, areas to be protected and areas to be improved. By means of the methodology for spatial and environmental assessment developed by Bustos Romero (2001), the survey selects characteristic points of each area in order to register the environmental data relative to the two basic seasons found in the region where the campus is located, that is, the dry and the rainy season, so that it can evaluate changes in the environment which might have been caused by urban density growth, by arborization or by the influence of the urban form. It then proceeds to a quantitative and statistical survey of the collected data with the purpose of evaluating the degree of influence of the identified features over the environmental variables along the different scales of approach. The study shows the existence of different microclimates and emphasizes the relevance of the bioclimatic analysis of the built environment as a tool for the decision-making process along the development of the Master Plan for UFRN Central Campus

Avaliação da influência do nacl em pastas de cimento portland para cimentação de poços de petróleo em zonas evaporíticas

One of the major current challenges for oilwell companies is the extraction of oil from evaporitic zones, also known as pre-salt basins. Deep reservoirs are found under thick salt layers formed from the evaporation of sea water. Salt layers seal the flow of oil from underneath rock formations, which store hydrocarbons and increase the probability of success in oil and gas exploration. Oilwells are cemented using Portland-based slurries to promote mechanical stability and zonal isolation. For pre-salt oilwells, NaCl must be added to saturate the cement slurries, however, the presence of salt in the composition of slurries affects their overall behavior. Therefore, the objective of the present study was to evaluate the effect of the addition of 5 to 25% NaCl on selected properties of Portland-based slurries. A series of tests were carried out to assess the rheological behavior, thickening time, free water and ultrassonic compressive strength. In addition, the slurries were also characterized by thermal analysis, X ray diffraction and scanning electron microscopy. The results showed that the addition of NaCl affected the thickening time of the slurries. NaCl contents up to 10% shortened the thickening time of the slurries. On the other hand, concentrations in excess of 20% not only extended the thickening time, but also reduced the strength of hardened slurries. The addition of NaCl resulted in the formation of a different crystalline phase called Friedel´s salt, where free chlorine is bonded to tricalcium aluminate

Influência da adição do NaCl e KCl em sistemas de pastas contendo sílica para poços de petróleo em zonas evaporíticas e carbonáticas

One of the major challenges faced nowadays by oil companies is the exploration of pre-salt basins. Thick salt layers were formed in remote ages as a consequence of the evaporation of sea water containing high concentrations of NaCl and KCl. Deep reservoirs can be found below salt formations that prevent the outflow of oil, thus improving the success in oil prospection. The slurries used in the cement operations of salt layers must be adequate to the properties of those specific formations. At the same time, their resulting properties are highly affected by the contamination of salt in the fresh state. It is t herefore important to address the effects of the presence of salt in the cement slurries in order to assure that the well sheath is able to fulfill its main role to provide zonal isolation and mechanical stability. In this scenario, the objective of the present thesis work was to evaluate the effect of the presence of NaCl and KCl premixed with cement and 40% silica flour on the behavior of cement slurries. Their effect in the presence of CO2 was also investigated. The rheological behavior of slurries containing NaCl and KCl was evaluated along with their mechanical strength. Thermal and microstructural tests were also carried out. The results revealed that the presence of NaCl and KCl affected the pozzolanic activity of silica flour, reducing the strength of the hardened slurries containing salt. Friedel´s salt was formed as a result of the bonding between free Cl- and tricalcium aluminate. The presence of CO2 also contributed to the degradation of the slurries as a result of a process of carbonation/bicarbonataion

Metodologia de utilização de dados de sensoriamento remoto em zonas costeiras sob influência da indústria petrolífera

Oil spills in marine environments represent immediate environmental impacts of large magnitude. For that reason the Environmental Sensitivity to Oil Maps constitute a major instrument for planning actions of containment and cleanup. For both the Environmental Sensitivity Maps always need to be updated, to have an appropriate scale and to represent accurately the coastal areas. In this context, this thesis presents a methodology for collecting and processing remote sensing data for the purpose of updating the territorial basis of thematic maps of Environmental Sensitivity to Oil. To ensure greater applicability of the methodology, sensors with complementary characteristics, which provide their data at a low financial cost, were selected and tested. To test the methodology, an area located on the northern coast of the Northeast of Brazil was chosen. The results showed that the products of ASTER data and image hybrid sensor PALSAR + CCD and HRC + CCD, have a great potential to be used as a source of cartographic information on projects that seek to update the Environmental Sensitivity Maps of Oil