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Search Results: 1 - 10 of 177341 matches for " de Andrade "
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Slow Plasma Dynamo Driven by Electric Current Helicity in Non-Compact Riemann Surfaces of Negative Curvature  [PDF]
Luiz Carlos Garcia de Andrade
Journal of Modern Physics (JMP) , 2010, DOI: 10.4236/jmp.2010.15046
Abstract: Boozer addressed the role of magnetic helicity in dynamos [1]. He pointed out that the magnetic helicity conservation implies that the dynamo action is more easily attainable if the electric potential varies over the surface of the dynamo. This provided motivated us to investigate dynamos in Riemannian curved surfaces [2]. Thiffeault and Boozer [3] discussed the onset of dissipation in kinematic dynamos. In this paper, when curvature is constant and negative, a simple laminar dynamo solution is obtained on the flow topology of a Poincare disk, whose Gauss curvature is K = –1. By considering a laminar plasma dynamo [4] the electric current helicity λ ≈ 2.34 m–1 for a Reynolds magnetic number of Rm ≈ 210 and a growth rate of magnetic field |γ| ≈ 0.022 are obtained. Negative constant curvature non-compact H2 manifold, has also been used in onecomponent electron 2D plasma by Fantoni and Tellez [5]. Chicone et al. (CMP (1997)) showed fast dynamos can be supported in compact H2. PACS: 47.65.Md.
Broken Symmetries in Spacetime with Torsion and Galactic Magnetic Fields without Dynamo Amplification  [PDF]
L. C. Garcia de Andrade
International Journal of Astronomy and Astrophysics (IJAA) , 2012, DOI: 10.4236/ijaa.2012.23022
Abstract: Since Kostelecky et al [Phys Rev Lett 100, 111102 (2008)], have shown that there is an intimate connection between spacetime with torsion and the possibility of constraining it to Lorentz violation, a renewed interest in torsion theories of gravity has arised. In this paper, minimal coupling between photons on a torsioned background is shown to allow us to obtain the galactic magnetic field strength μG without dynamo amplification. This agrees with recent results by Jimenez and Maroto (2011) for spiral galaxies, with galactic magnetic field constraints from Dark matter without dy- namo amplification. The approach discussed here allow us to get rid of the unpleasant photon mass by simply consider- ing the Lagrangean cut off for second order torsion terms. Therefore though the gauge and Lorentz symmetries are bro- ken here one does not have to deal with photon masses.
The Efficiency of CP-Violating α2-Dynamos from Primordial Cosmic Axion Oscillation with Torsion  [PDF]
L. C. Garcia de Andrade
International Journal of Astronomy and Astrophysics (IJAA) , 2015, DOI: 10.4236/ijaa.2015.51008
Abstract: Recently torsion fields were introduced in CP-violating cosmic axion a2-dynamos [Garcia de Andrade, Mod Phys Lett A, (2011)] in order to obtain Lorentz violating bounds for torsion. Here instead, oscillating axion solutions of the dynamo equation with torsion modes [Garcia de Andrade, Phys Lett B (2012)] are obtained taking into account dissipative torsion fields. Magnetic helicity torsion oscillatory contribution is also obtained. Note that the torsion presence guarantees dynamo efficiency when axion dynamo length is much stronger than the torsion length. Primordial axion oscillations due to torsion yield a magnetic field of 109 G at Nucleosynthesis epoch. This is obtained due to a decay of BBN magnetic field of 1015 G induced by torsion. Since torsion is taken as 10–20 s–1, the dynamo efficiency is granted over torsion damping. Of course dynamo efficiency is better in the absence of torsion. In the particular case when the torsion is obtained from anomalies it is given by the gradient of axion scalar [Duncan et al., Nuclear Phys B 87, 215] that a simpler dynamo equation is obtained and dynamo mechanism seems to be efficient when the torsion helicity, is negative while magnetic field decays when the torsion is positive. In this case an extremely huge value for the magnetic field of 1015 Gauss is obtained. This is one order of magnitude greater than the primordial magnetic fields of the domain wall. Actually if one uses tDW ~ 10-4 s one obtains BDW ~ 1022 G which is a more stringent limit to the DW magnetic primordial field.
Amazonian Fruits: An Overview of Nutrients, Calories and Use in Metabolic Disorders  [PDF]
Moacir Couto de Andrade Júnior, Jerusa Souza Andrade
Food and Nutrition Sciences (FNS) , 2014, DOI: 10.4236/fns.2014.517182
Abstract: Amazonian fruits are outstanding in quality. They are consumed as true delicacies of nature by the Brazilian population. Besides their attractive attributes, i.e. appearance, different textures and distinctive flavors, their nutritional value is diversified in the type of calories and the functional food ingredients. In addition to being very palatable, Amazonian fruits provide energy-rich macronutrients (lipids, proteins and carbohydrates), micronutrients (minerals, water-soluble vitamins and fat-soluble vitamins), prebiotics (dietary fibers, especially pectin), bioactive substances (carotenoids and polyphenols), variety in the diet and improvement in the organoleptic properties and digestibility of (mixed) foods. This study first aimed to review concepts applicable to nutritional constituents and caloric contents of Amazonian fruits. It also attempted to clarify the potential use of these fruits in metabolic disorders (i.e. diabetes mellitus and/or obesity). To fulfill these purposes, 12 fruits were chosen for their dietetic significance in the Brazilian Amazonia.
Technological Perspectives for Propulsion on Nuclear Attack Submarines  [PDF]
Luciano Ondir Freire, Delvonei Alves de Andrade
World Journal of Nuclear Science and Technology (WJNST) , 2016, DOI: 10.4236/wjnst.2016.64028
Abstract: This work aimed at proposing a new combination of technologies to improve military performances and reduce costs of nuclear attack submarines, without overlooking safety constraints. The last generation of nuclear attack submarines increased size to meet safety and operational requirements, imposing huge burden on costs side, reducing fleet size. The limitations of current Technologies employed were qualitatively discussed, explaining their limitations. There are new technologies (plate and shell heat exchangers) and architectural choices, like passive safety, and segregation of safety and normal systems, which may lead to reduction of costs and size of submarines. A qualitative analysis was provided on this combination of technologies, stressing their commercial nature and maturity, which reduced risks. The qualitative analysis showed the strong and weak points of this proposal, which adopted the concept of strength in numbers. Concluding, new Technologies enabled the existence of 3800 t nuclear attack submarines with powerful propulsion systems and good acoustic discretion.
The Role of Nuclear Power from a System Engineering Standpoint  [PDF]
Luciano Ondir Freire, Delvonei Alves de Andrade
World Journal of Nuclear Science and Technology (WJNST) , 2017, DOI: 10.4236/wjnst.2017.73015
Abstract: This work proposed the application of system engineering methods to identify organizations vital for society, seeking development and well-being. System engineering requires the identification of blocks (or systems), identification of their service functions, identification of states, identification of required quality and identification of constraints. Analyzing modern societies, vital functions were identified and countries behavior was modeled, identifying their states. In this context, nuclear power was found to be fundamental for development and defense because of its inherent advantages for military naval purposes at war. Another striking conclusion is that nuclear power is the best solution for country energy security, more than to avoid climate changes, but to help the nation to resist climate changes. A solution to mitigate the high overnight costs of nuclear power was also proposed. It was demonstrated qualitatively that the adoption of dual purpose mobile nuclear power plants military performances, economic development and risks management.
Technological Perspectives for Propulsion on Nuclear Attack Submarines  [PDF]
Rafael Radé Pacheco, Delvonei Alves de Andrade
World Journal of Nuclear Science and Technology (WJNST) , 2018, DOI: 10.4236/wjnst.2018.81001
Abstract: This work aims to present the historical context in which the current understanding of the phenomenon of the direct contact condensation started to call the scientific society attention. The development of nuclear power plants Light Water Reactors demanded a safe way to collect and treat the water used to cool the reactor. Some characteristics of this water in a high energetic thermodynamic state made it unsuitable to be directly discharged in the atmosphere. Small room relieves tanks were developed to contain this discharge. These tanks were partially fulfilled with water, and the vapor injection created a vapor plume. In the interface of liquid and vapor, the thermal exchange would be increased by the characteristic turbulence of this region.
Constructal Law of Institutions within Social Organizations  [PDF]
Luciano Ondir Freire, Delvonei Alves de Andrade
Open Journal of Applied Sciences (OJAppS) , 2018, DOI: 10.4236/ojapps.2018.83009
Abstract: This work looked for a unifying theory between physical-biological domain and social sciences. Constructal law unified physical and biological domain by telling the general sense in which flow systems tend to evolve. Management theory looks for relations between institutions and human agency. Although being state of mind entities, institutions follow constructal law. This work proposed the main organization flows are information and credit. Biologic instincts derived from Darwinian natural selection are the driving or blocking forces of such flows. Once biologic instincts systematically block information and credit flows in large numbers, this work proposed every human organization must have institutions to inhibit some behaviors. Those institutions need to be present, at least partially, in formal rules of social groups. This way it is possible to predict expansion or downfall of human groups using objective and quantifiable data. Therefore, further studies may employ classical history to confirm this theory. This work analyzed some case studies to show qualitatively the application of proposed theory. Concluding, this work gave physically-biologically grounded guidance for institutional changes.
Biochemical Changes of Cubiu Fruits (Solanum sessiliflorum Dunal, Solanaceae) According to Different Tissue Portions and Ripening Stages  [PDF]
Moacir Couto de Andrade Júnior, Jerusa Souza Andrade, Suely de Souza Costa
Food and Nutrition Sciences (FNS) , 2016, DOI: 10.4236/fns.2016.712111
Abstract: Cubiu fruits (Solanum sessiliflorum Dunal, Solanaceae) are known for their high nutritional value and low caloric content. This work aimed at evaluating biochemical indices of cubiu fruits according to different tissues (peel, pulp and placenta) and ripening stages (green, turning, ripe and fully ripe). The fruits were randomly harvested to investigate sensory aspects (colorimetry, blanching effect, pigments) and biochemical indices (moisture and dry matter, Total Soluble Solids (TSS), pH, Titratable Acidity (TA), TSS/TA ratio, ascorbic acid, Alcohol-Insoluble Solids (AIS), pectinesterase activity and pectin content). The analyses were performed at the laboratory of Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus, Brazil. The blanching process preserved pulp colors at all ripening stages. Chlorophylls were higher in green peels; flavonoids and carotenoids, in fully ripe peels. Anthocyanins were entirely absent. Pulp (turning fruits) showed the highest moisture content (91.05), followed by ripe pulp (90.70) and fully ripe pulp (90.62). Pulp TSS changed little whereas placenta TSS declined and were associated with increased TA and pH reduction (fully ripe fruits). Pulp pH and TA varied little whereas placenta pH was notably low and TA was remarkably high (fully ripe fruits). Pulp TSS/TA ratio showed predominance of TSS while in placenta, there was predominance of organic acids. AIS, precursors of pectin, were stable during ripening. The statistical analysis of dietary fiber content showed one modal value in the AIS. In pulp, pectinesterase activity correlated inversely with pectin content. Cubiu fruits were significant sources of bioactive compounds, e.g. chlorophylls, flavonoids and carotenoids, predominantly in the peel and the pulp; soluble functional fibers, e.g. pectin (g/100 g fresh weight), particularly in the green peel (1.00) and the fully ripe pulp (1.12), and other versatile molecules, e.g. ascorbic acid (mg/100 g fresh weight), especially in the fully ripe peel (32.45) and placenta (24.84) and the turning placenta (21.27). Cubiu fruits are rich in ascorbic acid and should be included in the human diet.
Relation between Gamma Decomposition and Powder Formation of γ-U8Mo Nuclear Fuel Alloys via Hydrogen Embrittlement and Thermal Shock  [PDF]
Fábio Branco Vaz de Oliveira, Delvonei Alves de Andrade
World Journal of Nuclear Science and Technology (WJNST) , 2014, DOI: 10.4236/wjnst.2014.44023
Abstract: Gamma uranium-molybdenum alloys have been considered as the fuel phase in plate type fuel elements for material and test reactors (MTR), due to their acceptable performance under irradiation. Regarding their usage as a dispersion phase in aluminum matrix, it is necessary to convert the as cast structure into powder, and one of the techniques considered for this purpose is the hydration-dehydration (HDH). This paper shows that, under specific conditions of heating and cooling, γ-UMo fragmentation occurs in a non-reactive predominant mechanism, as shown by the curves of hydrogen absorption/desorption as a function of time and temperature. Our focus was on the experimental results presented by the addition of 8% weight molybdenum. Following the production by induction melting, samples of the alloys were thermally treated under a constant flow of hydrogen for temperatures varying from 500°C to 600°C and for times of 0.5 to 4 h. It was observed that, even without a massive hydration-dehydration process, the alloys fragmented under specific conditions of thermal treatment during the thermal shock phase of the experiments. Also, it was observed that there was a relation between absorption and the rate of gamma decomposition or the gamma phase stability of the alloy.
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