Estudo da recuperação de óleo por drenagem gravitacional assistida por injeção de vapor

Steam assisted gravity drainage process (SAGD) involves two parallel horizontal wells located in a same vertical plane, where the top well is used as steam injector and the bottom well as producer. The dominant force in this process is gravitational. This improved oil recovery method has been demonstrated to be economically viable in commercial projects of oil recovery for heavy and extra heavy oil, but it is not yet implemented in Brazil. The study of this technology in reservoirs with characteristics of regional basins is necessary in order to analyze if this process can be used, minimizing the steam rate demand and improving the process profitability. In this study, a homogeneous reservoir was modeled with characteristics of Brazilian Northeast reservoirs. Simulations were accomplished with STARS , a commercial software from Computer Modelling Group, which is used to simulate improved oil recovery process in oil reservoirs. In this work, a steam optimization was accomplished in reservoirs with different physical characteristics and in different cases, through a technical-economic analysis. It was also studied a semi-continuous steam injection or with injection stops. Results showed that it is possible to use a simplified equation of the net present value, which incorporates earnings and expenses on oil production and expenses in steam requirement, in order to optimize steam rate and obtaining a higher net present value in the process. It was observed that SAGD process can be or not profitable depending on reservoirs characteristics. It was also obtained that steam demand can still be reduced injecting in a non continuous form, alternating steam injection with stops at several time intervals. The optimization of these intervals allowed to minimize heat losses and to improve oil recovery

Ver, lembrar e narrar: a conformação das memórias sobre a ditadura militar na recepção assistida do audiovisual

Subjective and socially constructed instance, the memory is not a natural phenomenon, but an area of contention between various social organizations for control and legitimation of a past. With the development of writing and the advent of new technical devices, it creates new ways to store and transport information. The memory is no longer restricted to the limits of the here and now of the subject and undergoes transformations. In this scenario, the media start to play an important role in publicizing and construction of embodiments of memory. This study aims to analyze the conformation of the memory of political groups during the process of receiving audiovisual fiction. For this purpose, a corpus of four chapters of the soap opera Love and Revolution was used as a cognitive device for remembering. The television series, broadcast by SBT between April 2011 and January 2012, went back to the beginning and development of the military dictatorship in Brazil, in the cities of Rio de Janeiro and São Paulo. Three militants of various affiliations Communists who acted against the regime in Rio Grande do Norte and neighboring states, were participants in this study. Using the method of oral history, the research was divided into two stages: in-depth interviews, which dealt with the history of life of employees with the militancy in the Communist parties and other social movements, and the assistance of a drive dramatic soap opera Love and Revolution. Comparing these two phases of the study, we analyze the flow of mediations that crossed memories of militancy and media framework; shifts the narrative of remembrance during reception, and the opposition between memory and represented the experiences of the receivers

Atividade antibacteriana do óleo essencial de Melampodium divaricatum (Rich.) DC., Asteraceae

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Caracterização magnética e estrutural de filmes depositados por gaiola catódica

Iron nitrite films, with hundred of nanometers thick, were deposited using the Cathodic cage plasma nitriding method, with a N2/H2 plasma, over a common glass substract. The structure, surface morphology and magnetic properties were investigated using X-ray diffractometry (XRD), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM). XRD shows the formation of γ FeN phase and a combination of ζFe2N + ɛFe3N phases. The film s saturation magnetization and coercivity depends on morphology, composition, grain size and treatment temperature. Temperature raising from 250 ºC to 350 ºC were followed by an increase in saturation magnetization and film s surface coercivity on the parallel direction in relative proportion. This fact can be attributed to the grain sizes and to the different phases formed, since iron rich fases, like the ɛFe3N phase, emerges more frequently on more elevated treatment s temperature. Using this new and reasonably low cost method, it was possible to deposit films with both good adhesion and good magnetic properties, with wide application in magnetic devices

Crescimento de filmes nanométricos monocristalinos de Fe/MgO(100) por "SPUTTERING" DC

The research behind this master dissertation started with the installation of a DC sputtering system, from its first stage, the adaptation of a refrigerating system, passing by the introduction of a heating system for the chamber using a thermal belt, until the deposition of a series of Fe/MgO(100) single crystal nanometric film samples. The deposition rates of some materials such as Fe, Py and Cu were investigated through an Atomic Force Microscope (AFM). For the single crystal samples, five of them have the same growth parameters and a thickness of 250Å, except for the temperature, which varies from fifty degrees from one to another, from 100ºC to 300ºC. Three other samples also have the same deposition parameters and a temperature of 300ºC, but with thickness of 62,5Å, 150Å, and 250Å. Magneto-optical Kerr Effect (MOKE) of the magnetic curves measurements and Ferromagnetic Resonance (FMR) were made to in order to study the influence of the temperature and thickness on the sample s magnetic properties. In the present dissertation we discuss such techniques, and the experimental results are interpreted using phenomenological models, by simulation, and discussed from a physical point of view, taking into account the system s free magnetic energy terms. The results show the growth of the cubic anisotropy field (Hac) as the sample s deposition temperature increases, presenting an asymptotic behavior, similar to the characteristic charging curve of a capacitor in a RC circuit. A similar behavior was also observed for the Hac due to the increase in the samples thicknesses. The 250˚A sample, growth at 300°C, presented a Hac field close to the Fe bulk value

Resolvendo problemas de fluxo de potência ótimo DC através de uma rede de hopfield modificada

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Analysis of the E-J Curve of HTS Tapes Under DC and AC Magnetic Fields at 77 K

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

DC and AC side harmonics in CCC converters

The capacitor-commutated converter (CCC) has frequently been used in the conception of HVDC systems connected to busbars with low short circuit level. This alternative arrangement, in substitution to the conventional ones, guarantees less sensitive operational conditions to problems related with the commutation failure in the inverters besides supplying part of the reactive energy to be compensated. Studies related with its performance in steady and transient states have been presented in several works, however its behavior as harmonic source is still little explored. This work presents preliminary studies focusing the generation of characteristic harmonics by this type of converter. Subjects related with the amplification of the harmonic magnitudes are investigated and compared considering similar arrangements of conventional static converters (LCC) and CCC schemes. It is also analyzed the harmonic generation on the dc side of the installation and its influence on the ac side harmonics. The results are obtained from simulations in the time domain in PSpice environment and they clearly illustrate the operational differences between the L CC and the CCC schemes with regard to characteristic harmonic generation.

Variable-Structure Control Design of Switched Systems With an Application to a DC-DC Power Converter

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

DCM Boost interleaved converter for operation in AC and DC to trolleybus application

This paper is based on the development and experimental analysis of a DCM Boost interleaved converter suitable for application in traction systems of electrical vehicles pulled by electrical motors (Trolleybus), which are powered by urban DC or AC distribution networks. This front-end structure is capable of providing significant improvements in trolleybuses systems and in the urban distribution network costs, and efficiency. The architecture of proposed converter is composed by five boost power cells in interleaving connection, operating in discontinuous conduction mode. Furthermore, the converter can operate as AC-DC converter, or as DC-DC converter providing the proper DC output voltage range required by DC or AC adjustable speed drivers. Therefore, when supplied by single-phase AC distribution networks, and operating as AC-DC converter, it is capable to provide high power factor, reduced harmonic distortion in the input current, complying with the restrictions imposed by the IEC 61000-3-4 standards. The digital controller has been implemented using a low cost FPGA and developed totally using a hardware description language VHDL and fixed point arithmetic. Thus, two control strategies are evaluated considering the compliance with input current restrictions imposed by IEC 61000-3-4 standards, the regular PWM modulation and a current correction PWM modulation. In order to verify the feasibility and performance of the proposed system, experimental results from a 15 kW low power scale prototype are presented, operating in DC and AC conditions.

Simulation Tools of DC-DC Converters for Power Electronics Education

This paper presents interactive simulation tools to support the enhancement of power electronics education considering DC to DC converters. These interactive tools make use of the benefits of Java language to provide a dynamic and interactive visualization of simulations in steady-state for idealized non-isolated DC to DC converters. Additionally, this paper discusses the features and the usage of the interactive educational tools to serve as a first design tool for the laboratory experiments in the power electronics courses. In this way, some results were confronted with a well-known simulator package and with experimental results in order to validate the developed interactive simulation tools.

Significados de família para adolescentes em liberdade assistida

Guided by the social-historical perspective, this research aimed to understand how the adolescents in Assisted Freedom measure have meaning the family institution. The Pastoral Minor, located in the city of Natal, was chosen as space of investigation, whose social-educative program is the source of our concerns about the attendance of adolescents in conflict with law. The corpus was accomplished, mainly, through the individual semi- structured interview with four adolescents and seven of their relatives that participated of the research. We use another instruments to constitute the corpus, like the documental research of the technical reports on the participants of program files, and the registered notes in the field diary. As resource to data treatment, we use the Thematic Content Analysis. The data discussion was focused on the three thematic units that emerged: Family, Social-Educational Measure, Family and Social-Educational Measure. On the adolescents perspective, the family configures as a group based on the existence of affective bonds. Despite of the vulnerability of their familiar reality and their wish for freedom with their peers, the affective bonds revealed it as being important in their lives. This study, glimpse possibilities to contribute for the construction of public politics and attendance programs, that can be closer of the social-familiar reality of the adolescents who are in conflict with the law and, in this case, to promote their access to the statute of subjects of rights

Influência do cálcio na calda de pulverização sobre a eficácia do carfentrazone-ethyl no controle de Euphorbia heterophylla

Alguns herbicidas podem ter sua eficácia de controle das plantas daninhas diminuída quando o cálcio encontra-se presente na calda de pulverização. Sendo assim, o presente trabalho foi desenvolvido com o objetivo de estudar a influência do cálcio na eficácia do herbicida carfentrazone-ethyl aplicado em pós-emergência sobre plantas adultas de Euphorbia heterophylla. Foram conduzidos dois experimentos com as concentrações de cálcio variando de 30 a 240 ppm e de 0 a 1.000 ppm respectivamente em cada experimento. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições. Observou-se que a eficácia do herbicida carfentrazone-ethyl não é afetada pela presença de cálcio em concentrações na calda de pulverização de até 1.000 ppm e que, na dose de 30 g i.a.ha-1 o herbicida é eficiente no controle de plantas adultas de E. heterophylla.

Síntese e caracterização de carreadores de oxigênio para combustão com recirculação química obtidos via reação de combustão assistida por microondas

Perovskites oxides win importance by its properties and commercials applications, they have a high thermal stability, have conductive properties, electrical, catalytic, electro catalytic, optical and magnetic, and are thermally stable. Because of these properties, are being widely studied as carriers of oxygen in the process of power generation with CO2 capture. In this work, the base carrier system La1-xMexNiO3 (Me = Ca and Sr) were synthesized by the method via the combustion reaction assisted by microwave. were synthesized from the combustion reaction method by microwave process. This method control the synthesi`s conditions to obtain materials with specific characteristics. The carriers calcined at 800 ° C/2h were analyzed by thermal analysis (TG-DTA), to verify its thermal stability, X-ray diffraction (XRD) to verify the phase formation, with subsequent refinement by the Rietveld method, to quantify the percentage of phases formed, the surface area by BET method was determined, scanning electron microscopy (SEM) was obtained to evaluate the material morphology and temperature programmed reduction (TPR) was done to observe the metallic phase of the nickel. After all proposed characterization and analysis of their results can be inferred to these oxides, key features so that they can be applied as carriers for combustion reactions in chemical cycles. The final products showed perovskite-type structures K2NiF4 (main) and ABO3.

DC Electric Field Dependence of the Dielectric Constant of Pzt Thin Films Prepared by Polymeric Precursor Method

This work reports dielectric measurements performed on Pb(Zr0.53Ti0.47)O3 (PZT) thin films prepared by a polymeric precursor method. The -E curves obtained for the PZT film measured at 100 kHz, under a small ac 0.2 kV/cm signal-test and a dc scan featured a typical butterfly curve. However, the -E curves obtained for PZT film under a dc scan, with a scan rate of 0.003 V/s, shows a pronounced asymmetry. The absence of a symmetric secondary peak in -E curves could be an indication of essentially 180 domain switching.