Time-domain analysis of piezoelectric impedance-based structural health monitoring using multilevel wavelet decomposition

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The effect of acoustic mode on time-resolved temperature measurements in a Rijke-tube pulse combustor

Radial profiles are reported of average and rms temperature in a propane flame for the first, second, and third acoustic modes at four different axial positions above the burner in a Rijke-tube combustor. Selected plots of the power spectral density (PSD) of temperature fluctuations are also reported. These radial profiles are then compared to similar ones made in the same flame, but in the absence of the acoustic field. Visual observations and photographs of the flame showed a remarkable change in flame height and structure with the onset of acoustic oscillations. This reduction in flame length, caused by the enhanced mixing due to the acoustic velocity fluctuations, gave rise to higher and lower average and rms temperatures near or well above the burner, respectively. In general, the PSD plots had a broad frequency content. The general trend was a decrease in magnitude with an increase in frequency. All cases presented broad-band peaks at around 5 Hz related to the flame flickering phenomenon. Preferred frequencies were observed in the oscillating PSD plots related to the fundamental frequency as well as subharmonics in the tube. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Continuously deformable topological structure

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Continuous-time and discrete-time sliding mode control accomplished using a computer

A computer-based sliding mode control (SMC) is analysed. The control law is accomplished using a computer and A/D and D/A converters. Two SMC designs are presented. The first one is a continuous-time conventional SMC design, with a variable structure law, which does not take into consideration the sampling period. The second one is a discrete-time SMC design, with a smooth sliding law, which does not have a structure variable and takes into consideration the sampling period. Both techniques are applied to control an inverted pendulum system. The performance of both the continuous-time and discrete-time controllers are compared. Simulations and experimental results are shown and the effectiveness of the proposed techniques is analysed.

Variable-Structure Control Design of Switched Systems With an Application to a DC-DC Power Converter

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

Real-time multi-sensors measurement system with temperature effects compensation for impedance-based structural health monitoring

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modeling the dielectric response of lanthanum modified lead zirconate titanate ferroelectric ceramics-an approach to the phase transitions in relaxor ferroelectrics

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

Dielectric response features and oxygen migration on rare earth modified lead titanate ferroelectric ceramics

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

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

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

Crystal structures of BnSP-7 and BnSP-6, two Lys49-phospholipases A(2): quaternary structure and inhibition mechanism insights

Phospholipases A(2) are components of Bothrops venoms responsible for disruption of cell membrane integrity via hydrolysis of its phospholipids. A class of PLA(2)-like proteins has been described which despite PLA(2) activity on artificial substrate, due to a D49K mutation, is still highly myonecrotic. This work reports the X-ray structure determination of two Lys49-PLA(2)s from Bothrops neuwiedi pauloensis (BnSP-7 and BnSP-6) and, for the first time, the comparison of eight dimeric Lys49-PLA2s. This comparison reveals that there are not just two (open and closed) but at least six different conformations. The binding of fatty acid observed in three recent Lys49-PLA(2) structures seems to be independent of their quaternary conformation. Cys29 polarization by Lys122 is not significant for BnSP-7 and BnSP-6 or other structures not bound by fatty acids. These structures may be in an active state when nothing is bound to them and the Lys122/Cys29 interactions are weak or absent. (C) 2003 Elsevier B.V. All rights reserved.

Crystal structure of a phospholipase A(2) homolog complexed with p-bromophenacyl bromide reveals important structural changes associated with the inhibition of myotoxic activity

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

Anti-poliovirus activity of Baccharis dracunculifolia and propolis by cell viability determination and real-time PCR

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Determination of lead in the absence of supporting electrolyte using carbon fiber ultramicroelectrode without mercury film

The determination of lead ions directly in water, for application in analysis of samples of environmental interest, was studied by electroanalytical techniques. Linear sweep anodic stripping voltammetry with a carbon fiber disk ultramicroelectrode (7.0 mu m in diameter), without mercury film, has been used for lead determination, by standard addition, in purified water in the absence of supporting electrolyte. The response was linear in the range from 10.0 to 50.0 mu g L-1, with a detection limit of 0.8 mu g L-1, for 300 s preconcentration time, at -1.2 V and 1.0 V s(-1) scan rate. The reliability of the analytical procedure was evaluated by precision using relative standard deviations (5.6%, for three repetitive stripping current measurements of solution with 10.0 mu g L-1 lead ions) and by the accuracy with recovery experiments (mean of 110.8%) for the same concentration.

In situ evaluation of anticancer drug methotrexate-DNA interaction using a DNA-electrochemical biosensor and AFM characterization

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Quantitative comparisons and models of time-averaging in bivalve and brachiopod shell accumulations

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