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São José dos Campos, Brazil

Lopez R.H.,INSA Rouen | Lemosse D.,INSA Rouen | De Cursi J.E.S.,INSA Rouen | Rojas J.,Vale Solucoes em Energia | El-Hami A.,INSA Rouen
Engineering Optimization | Year: 2011

This article aims at optimizing laminated composite plates taking into account uncertainties in the structural dimensions. As laminated composites require a global optimization tool, the Particle Swarm Optimization (PSO) method is employed. A new Reliability Based Design Optimization (RBDO) methodology based on safety factors is presented and coupled with PSO. Such safety factors are derived from the Karush-Kuhn-Tucker optimality conditions of the reliability index approach and eliminate the need for reliability analysis in RBDO. The plate weight minimization is the objective function of the optimization process. The results show that the coupling of the evolutionary algorithm with the safety-factor method proposed in this article successfully performs the RBDO of laminated composite structures. © 2011 Taylor & Francis. Source

Rojas J.E.,Vale Solucoes em Energia | Bendaou O.,National Institute for Applied Sciences, Strasbourg | El Hami A.,National Institute for Applied Sciences, Strasbourg | Rade D.,Federal University of Uberlandia
Multidiscipline Modeling in Materials and Structures | Year: 2010

Purpose - The purpose of this paper is to present a deterministic, stochastic and reliability analysis through numerical simulations in 2D and 3D dynamic fluid-structure interaction problems. Design/methodology/approach - The perturbation methods allied to reliability analysis are applied to fluid-structure finite element models. Reliability analysis couples finite element analysis with first and second order reliability methods and ant colony optimization in a modified first order reliability method. Findings - Results obtained show the potentialities of the proposed methodology and encourage improvement of this procedure for use in complex coupled fluid-structure systems. Originality/value - The understanding of the mechanical interaction between a fluid and an elastic solid has a capital importance in several industrial applications. In order to couple the behaviour of two different media, deterministic models have been proposed. However, stochastic analysis has been developed to deal with the statistical nature of fluid-structure interaction parameters. Moreover, probabilistic-based reliability analysis intends to find safe and cost-effective projects. © Emerald Group Publishing Limited. Source

Takahashi H.,National Institute for Space Research | Shiokawa K.,Nagoya University | Egito F.,National Institute for Space Research | Murayama Y.,Japan National Institute of Information and Communications Technology | And 2 more authors.
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2013

Upper mesosphere airglow emissions and temperature observed at Rikubetsu (43.5°N,143.8°E) and mesospheric winds observed at Wakkanai (45.4°N,141.8°E), Japan, from January to December 2005 were used to analyze periodic oscillations of 2-16 days. During the January to March period and after September, both winds and airglow demonstrated clear 8-, 10- and 16-day oscillations. Downward phase progressions observed in the oscillations indicate that these are a signature of Rossby mode planetary waves. The 16-day wave was more evident in the zonal wind than the meridional. The 10-day wave was observed in January and March, on the basis of only a few cycles superposed on the 16-day wave. Airglow OI 557.7nm, O2 and OH(6,2) band emissions and O2 rotational temperature also showed significant amplitude of oscillation induced by the wave passages. For the 10-day wave, OI557.7nm showed an amplitude of oscillation equals to or more than 50% of the mean intensity level, O2 ~45% and OH ~25%. Large amplitudes of oscillation of the airglow during the passage of planetary waves suggest the possible vertical transport of atomic oxygen in addition to the density and temperature variations intrinsic to the wave events. © 2013 Elsevier Ltd. Source

Paulino I.,National Institute for Space Research | Takahashi H.,National Institute for Space Research | Vadas S.L.,Colorado Research Associates | Wrasse C.M.,Vale Solucoes em Energia | And 4 more authors.
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2012

Medium-scale gravity waves (MSGWs) observed during the Conjugate Point Experiment (COPEX) at Boa Vista (2.8°N; 60.7°S, dip angle 21.7°) have been ray-traced and studied based on zero wind and model wind conditions. Wind profiles have been used from the TIE-GCM and HWM-07 models. Temperature profiles were used from the NRLMSISE-00 and TIE-GCM models, and TIMED/SABER satellite data. Doppler up-shifted MSGWs, at ~ 87 km of altitude, propagated to higher altitudes into the thermo-sphere-ionosphere domain than waves that were un-shifted. Most MSGWs propagated upwards up to ~ 140 km of altitude and were seen to be unlikely candidates to trigger equatorial plasma bubbles (EPBs) at the F layer bottom side. However, three of them propagated up to heights close to the F layer bottom side, where it could act in the EPB seeding directly. Moreover, three MSGWs, which propagated equatorward, could act on EPB seeding by field-line-integrated effects. © 2012 Elsevier Ltd. Source

Santos A.P.,Vale Solucoes em Energia | Andrade C.R.,Brazilian Technological Institute of Aeronautics
Journal of Aerospace Technology and Management | Year: 2012

For geographic regions where significant power demand and highest electricity prices occur during the warm months, a gas turbine inlet air cooling technique is a useful option for increasing output. Inlet air cooling increases the power output by taking advantage of the gas turbine's feature of higher mass flow rate, due the compressor inlet temperature decays. Industrial gas turbines that operate at constant speed are constant-volume-flow combustion machines. As the specific volume of air is directly proportional to the temperature, the increases of the air density results in a higher air mass flow rate, once the volumetric rate is constant. Consequently, the gas turbine power output enhances. Different methods are available for reducing compressor intake air temperature. There are two basic systems currently available for inlet cooling. The first and most cost-effective system is the evaporative cooling. Evaporative coolers make use of the evaporation of water to reduce the gas turbine inlet air temperature. The second system employs two ways to cool the inlet air: mechanical compression and absorption. In this method, the cooling medium flows through a heat exchanger located in the inlet duct to remove heat from the inlet air. In the present study, a thermodynamic analysis of gas turbine performance is carried out to calculate heat rate, power output and thermal efficiency at different inlet air temperature and relative humidity conditions. The results obtained with this model are compared with the values of the condition without cooling herein named of Base-Case. Then, the three cooling techniques are computationally implemented and solved for different inlet conditions (inlet temperature and relative humidity). In addition, the gas turbine was tested under different cooling methods for two Brazilian sites, and comparison between chiller systems (mechanical and absorption) showed that the absorption chiller provides the highest increment in annual energy generation with lower unit energy costs. On the other hand, evaporative cooler offered the lowest unit energy cost but associated with a limited cooling potential. Source

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