Estudo da corrosão no aço carbono 1020 protegido com óleo de coco saponificado: análise físico-química do comportamento químico do tensoativo

Corrosion inhibitors in solution are utilized to minimize processes from corrosion in steel. Of the present dissertation was evaluated the efficiency by inhibition from the surfactant saponified coconut oil (OCS) in the carbon steel 1020 through in linear polarization electrochemistry technique, well as, studied the process from adsorption through from the isotherms from Langmuir, Frumkin and Temkin. The corrosion current was determined through in Tafel extrapolation from the curves in the polarization, and then, was calculated the efficiency in the inhibitor to each concentration and temperature. Were studied four concentrations (12,5 ppm, 25 ppm, 50 ppm, and 75 ppm) in the inhibitor OCS and one in the NaCl salt (10.000 ppm) in six temperatures (301 K, 308 K, 313 K, 318 K, 323 K, and 328 K) in triplicate. By the results obtained observed that the technique applied can evaluated with rapidity and efficiency corrosion inhibitors. In relation to the isotherms, the than best appropriated was the in Langmuir and in the concentrations studied, the that obtained the best efficiency was the concentration of 75 ppm

Caracterização química e toxicológica da água produzida descartada em plataformas de óleo e gás na costa brasileira e seu comportamento dispersivo no mar

The production of oil and gas is usually accompanied by the production of water, also known as produced water. Studies were conducted in platforms that discharge produced water in the Atlantic Ocean due to oil and gas production by Petrobras from 1996 to 2006 in the following basins: Santos (Brazilian south region), Campos (Brazilian southeast region) and Ceara (Brazilian northeast region). This study encompasses chemical composition, toxicological effects, discharge volumes, and produced water behavior after releasing in the ocean, including dispersion plumes modeling and monitoring data of the marine environment. The concentration medians for a sampling of 50 samples were: ammonia (70 mg L-1), boron (1.3 mg L1), iron (7.4 mg L-1), BTEX (4.6 mg L-1), PAH (0.53 mg L-1), TPH (28 mg L-1); phenols (1.3 mg L-1) and radioisotopes (0.15 Bq L-1 for 226Ra and 0.09 Bq L-1 for 228Ra). The concentrations of the organic and inorganic parameters observed for the Brazilian platforms were similar to the international reference data for the produced water in the North Sea and in other regions of the world. It was found significant differences in concentrations of the following parameters: BTEX (p<0.0001), phenols (p=0.0212), boron (p<0.0001), iron (p<0.0001) and toxicological response in sea urchin Lytechinus variegatus (p<0.0001) when considering two distinguished groups, platforms from southeast and northeast Region (PCR-1). Significant differences were not observed among the other parameters. In platforms with large gas production, the monoaromatic concentrations (BTEX from 15.8 to 21.6 mg L-1) and phenols (from 2 to 83 mg L-1) were higher than in oil plataforms (median concentrations of BTEX were 4.6 mg L-1 for n=53, and of phenols were 1.3 mg L-1 for n=46). It was also conducted a study about the influence of dispersion plumes of produced water in the vicinity of six platforms of oil and gas production (P-26, PPG-1, PCR-1, P-32, SS-06), and in a hypothetical critical scenario using the chemical characteristics of each effluent. Through this study, using CORMIX and CHEMMAP models for dispersion plumes simulation of the produced water discharges, it was possible to obtain the dilution dimension in the ocean after those discharges. The dispersion plumes of the produced water modelling in field vicinity showed dilutions of 700 to 900 times for the first 30-40 meters from the platform PCR-1 discharge point; 100 times for the platform P-32, with 30 meters of distance; 150 times for the platform P-26, with 40 meters of distance; 100 times for the platform PPG-1, with 130 meters of distance; 280 to 350 times for the platform SS-06, with 130 meters of distance, 100 times for the hypothetical critical scenario, with the 130 meters of distance. The dilutions continue in the far field, and with the results of the simulations, it was possible to verify that all the parameters presented concentrations bellow the maximum values established by Brazilian legislation for seawater (CONAMA 357/05 - Class 1), before the 500 meters distance of the discharge point. These results were in agreement with the field measurements. Although, in general results for the Brazilian produced water presented toxicological effects for marine organisms, it was verified that dilutions of 100 times were sufficient for not causing toxicological responses. Field monitoring data of the seawater around the Pargo, Pampo and PCR-1 platforms did not demonstrate toxicity in the seawater close to these platforms. The results of environmental monitoring in seawater and sediments proved that alterations were not detected for environmental quality in areas under direct influence of the oil production activities in the Campos and Ceara Basin, as according to results obtained in the dispersion plume modelling for the produced water discharge

Caracterização química e toxicológica da água produzida descartada em plataformas de óleo e gás na costa brasileira e seu comportamento dispersivo no mar

The production of oil and gas is usually accompanied by the production of water, also known as produced water. Studies were conducted in platforms that discharge produced water in the Atlantic Ocean due to oil and gas production by Petrobras from 1996 to 2006 in the following basins: Santos (Brazilian south region), Campos (Brazilian southeast region) and Ceara (Brazilian northeast region). This study encompasses chemical composition, toxicological effects, discharge volumes, and produced water behavior after releasing in the ocean, including dispersion plumes modeling and monitoring data of the marine environment. The concentration medians for a sampling of 50 samples were: ammonia (70 mg L-1), boron (1.3 mg L1), iron (7.4 mg L-1), BTEX (4.6 mg L-1), PAH (0.53 mg L-1), TPH (28 mg L-1); phenols (1.3 mg L-1) and radioisotopes (0.15 Bq L-1 for 226Ra and 0.09 Bq L-1 for 228Ra). The concentrations of the organic and inorganic parameters observed for the Brazilian platforms were similar to the international reference data for the produced water in the North Sea and in other regions of the world. It was found significant differences in concentrations of the following parameters: BTEX (p<0.0001), phenols (p=0.0212), boron (p<0.0001), iron (p<0.0001) and toxicological response in sea urchin Lytechinus variegatus (p<0.0001) when considering two distinguished groups, platforms from southeast and northeast Region (PCR-1). Significant differences were not observed among the other parameters. In platforms with large gas production, the monoaromatic concentrations (BTEX from 15.8 to 21.6 mg L-1) and phenols (from 2 to 83 mg L-1) were higher than in oil plataforms (median concentrations of BTEX were 4.6 mg L-1 for n=53, and of phenols were 1.3 mg L-1 for n=46). It was also conducted a study about the influence of dispersion plumes of produced water in the vicinity of six platforms of oil and gas production (P-26, PPG-1, PCR-1, P-32, SS-06), and in a hypothetical critical scenario using the chemical characteristics of each effluent. Through this study, using CORMIX and CHEMMAP models for dispersion plumes simulation of the produced water discharges, it was possible to obtain the dilution dimension in the ocean after those discharges. The dispersion plumes of the produced water modelling in field vicinity showed dilutions of 700 to 900 times for the first 30-40 meters from the platform PCR-1 discharge point; 100 times for the platform P-32, with 30 meters of distance; 150 times for the platform P-26, with 40 meters of distance; 100 times for the platform PPG-1, with 130 meters of distance; 280 to 350 times for the platform SS-06, with 130 meters of distance, 100 times for the hypothetical critical scenario, with the 130 meters of distance. The dilutions continue in the far field, and with the results of the simulations, it was possible to verify that all the parameters presented concentrations bellow the maximum values established by Brazilian legislation for seawater (CONAMA 357/05 - Class 1), before the 500 meters distance of the discharge point. These results were in agreement with the field measurements. Although, in general results for the Brazilian produced water presented toxicological effects for marine organisms, it was verified that dilutions of 100 times were sufficient for not causing toxicological responses. Field monitoring data of the seawater around the Pargo, Pampo and PCR-1 platforms did not demonstrate toxicity in the seawater close to these platforms. The results of environmental monitoring in seawater and sediments proved that alterations were not detected for environmental quality in areas under direct influence of the oil production activities in the Campos and Ceara Basin, as according to results obtained in the dispersion plume modelling for the produced water discharge

Uma abordagem para a verificação do comportamento excepcional a partir de regras de designe e testes

Checking the conformity between implementation and design rules in a system is an important activity to try to ensure that no degradation occurs between architectural patterns defined for the system and what is actually implemented in the source code. Especially in the case of systems which require a high level of reliability is important to define specific design rules for exceptional behavior. Such rules describe how exceptions should flow through the system by defining what elements are responsible for catching exceptions thrown by other system elements. However, current approaches to automatically check design rules do not provide suitable mechanisms to define and verify design rules related to the exception handling policy of applications. This paper proposes a practical approach to preserve the exceptional behavior of an application or family of applications, based on the definition and runtime automatic checking of design rules for exception handling of systems developed in Java or AspectJ. To support this approach was developed, in the context of this work, a tool called VITTAE (Verification and Information Tool to Analyze Exceptions) that extends the JUnit framework and allows automating test activities to exceptional design rules. We conducted a case study with the primary objective of evaluating the effectiveness of the proposed approach on a software product line. Besides this, an experiment was conducted that aimed to realize a comparative analysis between the proposed approach and an approach based on a tool called JUnitE, which also proposes to test the exception handling code using JUnit tests. The results showed how the exception handling design rules evolve along different versions of a system and that VITTAE can aid in the detection of defects in exception handling code

Avaliando a robustez e manutenibilidade do comportamento excepcional de aplicações C#

Mainstream programming languages provide built-in exception handling mechanisms to support robust and maintainable implementation of exception handling in software systems. Most of these modern languages, such as C#, Ruby, Python and many others, are often claimed to have more appropriated exception handling mechanisms. They reduce programming constraints on exception handling to favor agile changes in the source code. These languages provide what we call maintenance-driven exception handling mechanisms. It is expected that the adoption of these mechanisms improve software maintainability without hindering software robustness. However, there is still little empirical knowledge about the impact that adopting these mechanisms have on software robustness. This work addresses this gap by conducting an empirical study aimed at understanding the relationship between changes in C# programs and their robustness. In particular, we evaluated how changes in the normal and exceptional code were related to exception handling faults. We applied a change impact analysis and a control flow analysis in 100 versions of 16 C# programs. The results showed that: (i) most of the problems hindering software robustness in those programs are caused by changes in the normal code, (ii) many potential faults were introduced even when improving exception handling in C# code, and (iii) faults are often facilitated by the maintenance-driven flexibility of the exception handling mechanism. Moreover, we present a series of change scenarios that decrease the program robustness

Estudo do comportamento mecânico de estruturas de solo-cimento reforçado com fibras de coco e hastes de bambu

In this work the use of coconut fiber (coir) and bamboo shafts as reinforcement of soil-cement was studied, in order to obtain an alternative material to make stakes for fences in rural properties. The main objective was to study the effect of the addition of reinforcement to the soil-cement matrix. The effect of humidity on the mechanical properties was also analyzed. The soil-cement mortar was composed by a mixture, in equal parts, of soil and river sand, 14% in weight of cement and 10 % in weight of water. As reinforcement, different combinations of (a) coconut fiber with 15 mm mean length (0,3 %, 0,6 % and 1,2 % in weight) and (b) bamboo shafts, also in crescent quantities (2, 4 and 8 shafts per specimen) were used. For each combination 6 specimens were made and these were submitted to three point flexural test after 28 days of cure. In order to evaluate the effect of humidity, 1 specimen from each of the coconut fiber reinforced combination was immersed in water 24 hours prior to flexural test. The results of the tests carried out indicated that the addition of the reinforcement affected negatively the mechanical resistance and, on the other hand, increased the tenacity and the ductility of the material.

Atividade cromosférica induzida por planetas extrasolares gigantes

In the present work, we have analyzed the behavior of the chromospheric activity of stars with planets, as a function of different planetary parameters, searching for possible effects of planets on the chromosphere of the hosting star. For this study we have selected a sample of 73 main sequence stars with planets, of spectral types F, G and K. Our analysis shows that among stars with planets presenting semi-major axis smaller than 0.15 AU, a few ones present enhanced CaII emission flux, paralleling recent results found in the literature for coronal X-ray flux. Nevertheless, in contrast to Kashyap et al. (2008), who claim that enhanced X-ray flux in stars with planets is associated to massive close-in planetary companions, we suggest that such an aspect, at least in the context of CaII emission flux, is rather an effect of stellar sample selection. We have also studied the behavior of the CaII emission as a function of orbital parameters such as orbital period and eccentricity, and no clear trend was found, reinforcing our present suggestion that enhanced chromospheric activity in stars with planets is an intrinsic stellar phenomenon

Parâmetros físico-químicos de estrelas com planetas na missão CoRoT

In the present study we compute the atmospheric parameters (Teff , log g and vmic, [Fe/H]) and chemical abundance of 16 ions (Fe I, Fe II, O I, Si I, Na I, Mg I, Al I, Ca I, Ti I, Co I, Ni I, Rb I, Zr I, Ba II, La II and Cr I) for 16 solar-like stars with masses between 0:8 and 1:2 Mfi aproximatedly, including 10 planet-host stars detected by the CoRoT Space Mission. For this study, we use data from the ESO public archive: (i) high resolution spectra (R 47000) from the UVES spectrograph on the VLT/UT2-ESO (for 7 stars, covering the wavelength range 3450-4515 Å and 5500-9400 Å) and (ii) high resolution spectra from HARPS spectrograph on the La Silla-ESO 3.60 m telescope (for 9 stars, covering the wavelength range 4200-6865 Å). Our spectral analysis is based on MARCS models of atmosphere and Turbospectrum spectroscopic tools. On the base of the computed parameters, the referred abundances appears to follow the same behavior of the solar curve abundances. Further, one observes a signifficant correlation between the abundance ratio [m/Fe] and condensation temperature (Tc) of refractory elements (Tc > 900 K). The behavior of the projected rotational velocity (v sin i) versus the computed abundances [m/Fe] is also analyzed, presenting no clear trends. This study oers additional constraints to trace the evolutive history of solar-like stars with planets, including the search for chemical dierences between stars with and without transit planets and anomalies in the studied abundances