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Search Results: 1 - 10 of 594160 matches for " J. M.;Brasil "
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On non-ideal and non-linear portal frame dynamics analysis using bogoliubov averaging method
Palacios, J. L.;Balthazar, J. M.;Brasil, R. M. L. R. F.;
Journal of the Brazilian Society of Mechanical Sciences , 2002, DOI: 10.1590/S0100-73862002000400002
Abstract: we apply the bogoliubov averaging method to the study of the vibrations of an elastic foundation, forced by a non-ideal energy source. the considered model consists of a portal plane frame with quadratic nonlinearities, with internal resonance 1:2, supporting a direct current motor with limited power. the non-ideal excitation is in primary resonance in the order of one-half with the second mode frequency. the results of the averaging method, plotted in time evolution curve and phase diagrams are compared to those obtained by numerically integrating of the original differential equations. the presence of the saturation phenomenon is verified by analytical procedures.
A short note on a nonlinear system vibrations under two non-ideal excitations
Palacios, J. L.;Balthazar, J. M.;Brasil, R. M. L. R. F.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2003, DOI: 10.1590/S1678-58782003000400011
Abstract: this paper describes a nonlinear phenomenon in the dynamical behavior of a nonlinear system under two non-ideal excitations: the self-synchronization of unbalanced direct current motors. the considered model is taken as a duffing system that is excited by two unbalanced direct current motors with limited power supplies. the results obtained by using numerical simulations are discussed in details
On non-ideal and non-linear portal frame dynamics analysis using bogoliubov averaging method
Palacios J. L.,Balthazar J. M.,Brasil R. M. L. R. F.
Journal of the Brazilian Society of Mechanical Sciences , 2002,
Abstract: We apply the Bogoliubov Averaging Method to the study of the vibrations of an elastic foundation, forced by a Non-ideal energy source. The considered model consists of a portal plane frame with quadratic nonlinearities, with internal resonance 1:2, supporting a direct current motor with limited power. The non-ideal excitation is in primary resonance in the order of one-half with the second mode frequency. The results of the averaging method, plotted in time evolution curve and phase diagrams are compared to those obtained by numerically integrating of the original differential equations. The presence of the saturation phenomenon is verified by analytical procedures.
A short note on a nonlinear system vibrations under two non-ideal excitations
Palacios J. L.,Balthazar J. M.,Brasil R. M. L. R. F.
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2003,
Abstract: This paper describes a nonlinear phenomenon in the dynamical behavior of a nonlinear system under two non-ideal excitations: the self-synchronization of unbalanced direct current motors. The considered model is taken as a Duffing system that is excited by two unbalanced direct current motors with limited power supplies. The results obtained by using numerical simulations are discussed in details
Electronic and optical properties of InGaAs quantum wells with Mn-delta-doping GaAs barriers
Udson C. Mendes,M. A. G. Balanta,Maria J. S. P. Brasil,José A. Brum
Physics , 2015,
Abstract: We present here the electronic structure and optical properties of InGaAs quantum wells with barrier doped with Manganese. We calculated the electronic states and optical emission within the envelope function and effective mass approximations using the spin-density functional theory in the presence of an external magnetic field. We observe magneto-oscillations of the Landau levels at low-magnetic fields (B < 5 T) that are dominated by the magnetic interaction between holes spin and Mn spin, while at high magnetic fields the spin-polarization of the hole gas is the dominant effect. Our results also show that a gate voltage alter significantly the magneto-oscillations of the emission energy and may be an external control parameter for the magnetic properties of the system. Finally, we discuss the influence of the Landau Levels oscillations in the emission spectra and compare with available experimental.
Construction and Validation of an Educational Technology for Mammary Health Promotion  [PDF]
Izabel C. F. J. Barbosa, Ana Fátima C. Fernandes, Camila Brasil Moreira, Míria C. L. Santos, Altamira M. F. Gomes, Ivna Silva Andrade, Anna Paula Sousa da Silva
Open Journal of Nursing (OJN) , 2015, DOI: 10.4236/ojn.2015.511102
Abstract: Mammary health is issue faced by public health nurses and the science follows new ways into this thematic area of learning course wares. The purpose of this study was to construct and to validate a distance course for mammary health promotion for nurses. Methodological proposal has been composed of five stages: 1) analysis and planning, 2) modeling, 3) implementation, 4) evaluation and maintenance and 5) distribution. A total of nine experts as research population were consulted who were expert judges of nursing, pedagogy and web designer, three of each specific area, which were included in the study. The variables that had concordance index of 50% were: graphic designer pages favors learning, the user has easy navigation, the learning of the student experience, the environment provides interdisciplinary, content is built on process rather than there is a unique sequence, allows access to the available environment and holds a discussion on the subject. The distance learning course is intended to broaden and to enrich the living spaces and construct their own knowledge, favors interactivity, communication, autonomy and cooperation between the participants and provides access to educational technologies.
Influence of the synthesis conditions on the characteristics and metal adsorption properties of the 3-(1,4-phenylenediamine)propylsilica xerogel
Vaghetti, J. C. P;Brasil, J. L.;Costa, T. M. H;Lima, E. C.;Benvenutti, E.V;
Eclética Química , 2005, DOI: 10.1590/S0100-46702005000400006
Abstract: the hybrid 3-(1,4-phenylenediamine)propylsilica xerogel was obtained starting from two different organic precursor quantity (5 and 8 mmol) to 22 mmol of teos, in the synthesis. the xerogel samples were characterized by using chn elemental analysis, n2 adsorption-desorption isotherms, infrared thermal analysis. the xerogel was used as metal sorbent for cu2+, cd2+ and pb2+ in aqueous solution with concentration range of 10-3 to 10-5 mmol l-1. the quantity of organic precursor added in the synthesis influences the characteristics of the xerogel as morphology and thermal stability, as well as the metal adsorption capacity.
Analysis of Regular and Irregular Dynamics of a Non Ideal Gear Rattling Problem
Souza, S. L. T. de;Caldas, I. L.;Balthazar, J. M.;Brasil, R. M. L. R. F.;
Journal of the Brazilian Society of Mechanical Sciences , 2002, DOI: 10.1590/S0100-73862002000200005
Abstract: this paper presents a study on the dynamics of the rattling problem in gearboxes under non-ideal excitation. the subject has being analyzed by a number of authors such as karagiannis and pfeiffer (1991), for the ideal excitation case. an interesting model of the same problem by moon (1992) has been recently used by souza and caldas (1999) to detect chaotic behavior. we consider two spur gears with different diameters and gaps between the teeth. suppose the motion of one gear to be given while the motion of the other is governed by its dynamics. in the ideal case, the driving wheel is supposed to undergo a sinusoidal motion with given constant amplitude and frequency. in this paper, we consider the motion to be a function of the system response and a limited energy source is adopted. thus an extra degree of freedom is introduced in the problem. the equations of motion are obtained via a lagrangian approach with some assumed characteristic torque curves. next, extensive numerical integration is used to detect some interesting geometrical aspects of regular and irregular motions of the system response.
Analysis of Regular and Irregular Dynamics of a Non Ideal Gear Rattling Problem
Souza S. L. T. de,Caldas I. L.,Balthazar J. M.,Brasil R. M. L. R. F.
Journal of the Brazilian Society of Mechanical Sciences , 2002,
Abstract: This paper presents a study on the dynamics of the rattling problem in gearboxes under non-ideal excitation. The subject has being analyzed by a number of authors such as Karagiannis and Pfeiffer (1991), for the ideal excitation case. An interesting model of the same problem by Moon (1992) has been recently used by Souza and Caldas (1999) to detect chaotic behavior. We consider two spur gears with different diameters and gaps between the teeth. Suppose the motion of one gear to be given while the motion of the other is governed by its dynamics. In the ideal case, the driving wheel is supposed to undergo a sinusoidal motion with given constant amplitude and frequency. In this paper, we consider the motion to be a function of the system response and a limited energy source is adopted. Thus an extra degree of freedom is introduced in the problem. The equations of motion are obtained via a Lagrangian approach with some assumed characteristic torque curves. Next, extensive numerical integration is used to detect some interesting geometrical aspects of regular and irregular motions of the system response.
Avalia??o de genótipos de piment?o no período de inverno, em Araguari, MG
Peixoto, José Ricardo;Ramos, Rogério de Sousa;Faria Júnior, Brasil;Silva, Célio M. da;Angelis, Bruno de;
Pesquisa Agropecuária Brasileira , 1999, DOI: 10.1590/S0100-204X1999001000013
Abstract: an experimental field was carried out in the jord?o farm, located in araguari, mg, brazil, at 18o38'30" s and 48o11'18" w, during the winter season, with the purpose of evaluating the agronomic potential of sweet pepper cultivars. the experimental design was in randomized blocks with 17 treatments (17 genotypes) with four replications. the experimental plots were made up each of one line with 30 plants, with 1 m of space between lines and 0,45 m between plants. a total of ten harvestings were made starting on july 28, 1996 (77 days after transplanting) and ending on november 9, 1996. several f1 hybrids as lygia f1, magali f1, magali r f1, acuário f1, luis f1, fresco (bs 50-30) f1 and sambor f1 showed good agronomic characteristics, enabling them to be cultivated in the region, in the winter season. the lygia f1 cultivar was the highest producer (followed by acuário f1 and magali f1) and also showed the highest number of fruits. however, these fruits presented a square shape and fruit classification under the extra aa class. the acuário f1, sambor f1, fresco (bs 50-30) f1, luis f1 and all big genotypes produced a high number of fruits extra aa, while magna super, nacional ag-506, itaipu and hércules ag-672 showed a high percentage of fruits classified as extra a.
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