Suppression of vibrations in a nonlinear half-car model using a magneto-rheological damper

The present work investigates the nonlinear response of a half-car model. The disturbances of the road are assumed to be sinusoidal. After constructing the bifurcation diagram, we use the 0-1 test to identify chaotic motions. The main objective of this study is to eliminate chaotic behavior of the chassis and reduce its vibrations. To accomplish this, a semi-active vehicle suspension control system, using magneto-rheological dampers, is proposed. The proposed semi-active control strategy consists of two nonlinear control laws: a feedforward control, and a feedback control. They are obtained by considering the SDRE (State Dependent Riccati Equation) control, where the control parameter is the voltage applied to the coils of the magneto-rheological dampers. Numerical results show that the proposed control method is effective in significantly reducing of the chassis vibration, increasing, therefore, passenger comfort.

Chaos control and sensitivity analysis of a double pendulum arm excited by an RLC circuit based nonlinear shaker

In this paper the dynamical interactions of a double pendulum arm and an electromechanical shaker is investigated. The double pendulum is a three degree of freedom system coupled to an RLC circuit based nonlinear shaker through a magnetic field, and the capacitor voltage is a nonlinear function of the instantaneous electric charge. Numerical simulations show the existence of chaotic behavior for some regions in the parameter space and this behaviour is characterized by power spectral density and Lyapunov exponents. The bifurcation diagram is constructed to explore the qualitative behaviour of the system. This kind of electromechanical system is frequently found in robotic systems, and in order to suppress the chaotic motion, the State-Dependent Riccati Equation (SDRE) control and the Nonlinear Saturation control (NSC) techniques are analyzed. The robustness of these two controllers is tested by a sensitivity analysis to parametric uncertainties.

Teores e quantidade de alguns elementos no córrego Lavapés, sub-bacia do rio Sorocaba, São Paulo, Brasil

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

Cálculo em elementos finitos das frequências naturais dos modos de flexão de uma linha de eixo de unidade geradora hidráulica em escala

Pós-graduação em Engenharia Mecânica - FEG

Fabricação e caracterização elétrica de filmes nanoestruturados de derivados do politiofeno

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

O processo de liderança na perspectiva de enfermeiros da estratégia de saúde da família de Botucatu: uma pesquisa-ação

Pós-graduação em Enfermagem - FMB

A geometria presente em alguns livros didáticos dos anos finais do ensino fundamental

Pós-graduação em Educação Matemática - IGCE

Indicadores de bibliotecas universitárias: criação de índice de desenvolvimento baseado em redes de conhecimento compartilhado

Pós-graduação em Ciência da Informação - FFC

Células-combustível a etanol direto embarcadas em aeronaves: estudo de utilização e recuperação de calor residual

Pós-graduação em Engenharia Mecânica - FEG

Análise de junta aparafusada de biela automotiva

Pós-graduação em Engenharia Mecânica - FEG

Buracos sônicos em superfícies esféricas

Pós-graduação em Física - IFT

Governamentalidades neoliberais e dispositivos de segurança

Este artigo visa a realizar um debate teórico por meio das análises de Michel Foucault e de Robert Castel, entre outros, a respeito dos mecanismos de segurança e das estratégias de governamentalidade neoliberal, na sociedade contemporânea. Os cursos Em defesa da sociedade, Segurança, território e população e Nascimento da Biopolítica, de Foucault, inauguraram uma discussão relevante a respeito dos racismos de Estado e de sociedade, de seus paradoxos, nas democracias, e de seus efeitos a partir da emergência do neoliberalismo norte-americano e alemão, após a II Guerra Mundial, que foram difundidos em outros países, sobretudo na década de noventa do século XX, com especificidades em cada país, mas com pontos de conexão que nos permitem traçar um diagrama da sociedade de segurança e de como ela opera por táticas de governo das condutas, também denominadas governamentalidades, por Foucault.

CIRCULATION AND SUSPENDED PARTICULATE MATTER TRANSPORT IN A TIDALLY DOMINATED ESTUARY: CARAVELAS ESTUARY, BAHIA, BRAZIL

The circulation and transport of suspended particulate matter in the Caravelas Estuary are assessed. Nearly-synoptic hourly hydrographic, current (ADCP velocity and volume transport) and suspended particulate matter data were collected during a full semidiurnal spring tide, on the two transects Boca do Tomba and Barra Velha and on longitudinal sections at low and high tide. On the first transect the peak ebb currents (-1.5 ms(-1)) were almost twice as strong as those of the wider and shallow Barra Velha inlet (-0.80 ms(-1)) and the peak flood currents were 0.75 and 0.60 ms(-1), respectively. Due to the strong tidal currents both inlets had weak vertical salinity stratification and were classified with the Stratification-circulation Diagram as Type 2a (partially mixed-weakly stratified) and Type 1a (well mixed). Volume transports were very close, ranging from -3,500 to 3,100 m(3)s(-1) at the ebb and flood, respectively, with a residual -630 m(3)s(-1). The concentration of the suspended particulate matter was closely related to the tidal variation and decreased landwards from 50 mg. L(-1) at the estuary mouth, to 10 mg.L(-1) at distances of 9 and 16 km for the low and high tide experiments, respectively. The total residual SPM transport was out of the estuary at rates of -18 tons per tidal cycle.

A two-layer approximation to the Brazil Current-Intermediate Western Boundary Current System between 20 degrees S and 28 degrees S

It has been shown that the vertical structure of the Brazil Current (BC)-Intermediate Western Boundary Current (IWBC) System is dominated by the first baroclinic mode at 22 degrees S-23 degrees S. In this work, we employed the Miami Isopycnic Coordinate Ocean Model to investigate whether the rich mesoscale activity of this current system, between 20 degrees S and 28 degrees S, is reproduced by a two-layer approximation of its vertical structure. The model results showed cyclonic and anticyclonic meanders propagating southwestward along the current axis, resembling the dynamical pattern of Rossby waves superposed on a mean flow. Analysis of the upper layer zonal velocity component, using a space-time diagram, revealed a dominant wavelength of about 450 km and phase velocity of about 0.20 ms(-1) southwestward. The results also showed that the eddy-like structures slowly grew in amplitude as they moved downstream. Despite the simplified design of the numerical experiments conducted here, these results compared favorably with observations and seem to indicate that weakly unstable long baroclinic waves are responsible for most of the variability observed in the BC-IWBC system. (C) 2009 Elsevier Ltd. All rights reserved.

Tecidos gráficos da cultura e a expansão dos sistemas de escritas

Ensaio argumentativo sobre a concepção de escrita fora da perspectiva etnocêntrica que considera o sistema verbal alfabético ocidental como pólo da formulação conceitual e teórica. A hipótese fundamental em estudo encaminha a abordagem sistêmica a partir da qual a escrita é sistema ambiental de constituição semiótico-cognitiva fundado em possibilidades combinatórias e interpretativas de leitura. Examina-se, então, a perspectiva semiocêntrica fundada pela temporalidade da cultura e não apenas pela dominante espacial.