The non-ideal problem behavior using a dynamic vibration absorber with nonlinear essential stiffness and timedependent damping properties

The purpose of this study is to develop a dynamic vibration absorber using viscoelastic material with nonlinear essential stiffness and time-dependent damping properties for a non-ideal vibrating system with Sommerfeld effect, resonance capture, and jump phenomenon. The absorber is a mass-bar subsystem that consists of a viscoelastic bar with memory attached to mass, in which the internal dissipative forces depend on current, deformations, and its operational frequency varies with limited temperature. The non-ideal vibrating system consists of a linear (nonlinear) oscillator (plane frame structure) under excitation, via spring connector, of a DC-motor with limited power supply. A viscoelastic dynamic absorber modeled with elastic stiffness essentially nonlinearities was developed to further reduce the Sommerfeld effect and the response of the structure. The numerical results show the performance of the absorber on the non-ideal system response through the resonance curves, time histories, and Poincarésections. Furthermore, the structure responses using the viscoelastic damper with and without memory were studied. © IMechE 2012.

A note on non-linear phenomena in a non-ideal oscillator, with a snap-through truss absorber, including parameter uncertainties

This work considers the vibrating system that consists of a snap-through truss absorber coupled to an oscillator under excitation of an electric motor with an eccentricity and limited power, characterizing a non-ideal oscillator. It is aimed to use the non-linearity and quasi-zero stiffness of absorber (snap-through truss absorber) to obtain a significantly attenuation the jump phenomenon. There is also an interest to exhibit the reduction of Sommerfeld effect, to confirm the saturation phenomenon occurrence and show the power transfer in a non-linear structure, evidencing the pumping energy. As shown by simulations in this work, this absorber allows the energy pumping before and during the jump phenomenon, decreasing the higher amplitudes of considered system. Additionally, the occurrence of saturation phenomenon due use of snap-through truss absorber is verified. The analysis of parameter uncertainties was introduced. Sensitivity of system with parametric errors demonstrated a trustable system. © IMechE 2012.

Padrão de coordenação do pular corda: um estudo desenvolvimental

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A estabilidade do pular corda em diferentes padrões motores do saltar

Pós-graduação em Ciências da Motricidade - IBRC

Padronização do teste de corrida atada em velocistas: análise da relação entre potência e desempenho em corrida

Pós-graduação em Ciências da Motricidade - IBRC

Bainha de segurança para acondicionamento de facão canavieiro durante sua vida útil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O papel do brincar na apropriação da linguagem escrita

Pós-graduação em Educação - FFC

Dinâmica ressonante de alguns satélites artificiais terrestres no sistema Terra-Lua-Sol

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Condutividade elétrica e polarização térmica de vidros soda-cal-sílica contendo diferentes cátions tetravalentes

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

Capital flows to Latin America: third quarter 2001

Events in Argentina dominated most of the third quarter of 2001 until September 11, when the terrorist attacks against the United States prompted a sell-off of emerging markets assets, increasing uncertainty and risk aversion against a background of global economic slowdown. Emerging markets' short term prospects to tap international capital markets deteriorated significantly. In the third quarter of 2001, Latin American countries issued US$7.6 billion in bonds, following US$11.2 billion in the second quarter and US$13.2 billion in the first quarter, which had been a jump from only US$2.9 billion in the last quarter of 2000. At first, it seemed that the pace of debt issuance would slow down considerably given Argentina's troubles in July, as Argentina's bond auction at the beginning of the month was poorly received, forcing the government to shorten the maturity of the new debt and to pay rates as high as those during the Russian crisis in 1998. By August, however, emerging markets rebounded strongly on the back of a new US$8 billion IMF assistance package to Argentina, with both Mexico and Brazil successfully launching large issues. International markets displayed considerable flexibility as investors gave Mexico's US$1.5 billion 30- year bond and Brazil's JPY200 billion two-year samurai issue a warm reception. This return to capital markets was interrupted by the events of September 11, which caused debt issuance to fall sharply in September and October. Following the events of September 11, EMBI+ spreads widened above 1,000 basis points for the first time in nearly two years. According to J.P. Morgan there was a 3.7% market decline in September, which brought year-to-date returns for the EMBI+ to only 0.06%. Emerging markets debt, however, fared better than most other fixed income and equity markets in the immediate aftermath of the attacks. U.S. high-yield market suffered its worst month since August 1998, declining by 6.5%, while the S&P 500 and Nasdaq declined by 8.2% and 17%, respectively. Emerging equity markets suffered even greater declines, with losses as severe as 24% in local currency terms and 31% in U.S. dollar terms.

Uma análise da dinâmica do pêndulo eletromecânico utilizando a teoria de pertubações

Pós-graduação em Matemática - IBILCE

Cultura organizacional e avaliação em larga escala: faces e interfaces a partir da análise de escolas públicas municipais

Pós-graduação em Educação - FFC

Economic Survey of the Caribbean 2013: Improved economic performance with reduced downside risks

Includes bibliography.

Análise de assimetria dos membros inferiores por meio de salto horizontal unipodal e resistência muscular unilateral utilizando Leg Press horizontal

Pós-graduação em Engenharia Mecânica - FEG

Estudo comparativo de um salto vertical praticado por indivíduos na água e no solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)