Inclusão do efeito corona em modelos de linhas de transmissão bifásica utilizando a técnica de variáveis de estado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comportamento reológico de gomas guar e xantana na presença de polióis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito do manejo alimentar nos Parâmetros nutricionais e comportamento ingestivo em cabras leiteiras

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Propiedades Eléctricas en Membranas de Complejos Electrolitos Poliméricos PVA-OH/LI2SO4/PEG400

Lithium ion conducting polymer electrolytes based on polyvinyl Alcohol (PVA-OH) complexed with salt Li2SO4 and different weight percent ratios of PEG(400) plasticizer have been prepared by solution cast technique using deionized water as solvent. The thermogravimetric analysis (TGA) showed that the thermal stability of the materials depended on the plasticizer content. The FTIR study confirmed the polymer salt complex formation. The modulus spectra indicated the non-Debye nature of the material; a dominant relaxation process is visible being associated with the dynamic glass transition, relaxation-a. The maximum of each peak is shifted to higher frequencies as the plasticizer increases due to an enhancement of dipolar mobility in the origin of cooperative motions. A power law frequency dependence of the real part of the electrical conductivity is observed, which is characteristic of the effects of ion-ion and/or ion-chain correlations in ion motion. This variation is well fitted to a Jonscher's expression.

Reconstruction of the gravitational wave signal h(t) during the Virgo science runs and independent validation with a photon calibrator

The Virgo detector is a kilometer-scale interferometer for gravitational wave detection located near Pisa (Italy). About 13 months of data were accumulated during four science runs (VSR1, VSR2, VSR3 and VSR4) between May 2007 and September 2011, with increasing sensitivity. In this paper, the method used to reconstruct, in the range 10 Hz-10 kHz, the gravitational wave strain time series h(t) from the detector signals is described. The standard consistency checks of the reconstruction are discussed and used to estimate the systematic uncertainties of the h(t) signal as a function of frequency. Finally, an independent setup, the photon calibrator, is described and used to validate the reconstructed h(t) signal and the associated uncertainties. The systematic uncertainties of the h(t) time series are estimated to be 8% in amplitude. The uncertainty of the phase of h(t) is 50 mrad at 10 Hz with a frequency dependence following a delay of 8 mu s at high frequency. A bias lower than 4 mu s and depending on the sky direction of the GW is also present.

EMG amplitude and frequency parameters of muscular activity: Effect of resistance training based on electromyographic fatigue threshold

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Optical transition probabilities and compositional dependence of Judd-Ofelt parameters of Er3+ ions in fluoroindate glass

Fluoroindate glasses containing 1, 2, 3, and 4 mol% ErF3 were prepared in a dry box under an argon atmosphere. Absorption spectra of these glasses at room temperature were obtained. The Judd-Ofelt parameters Ωλ (λ = 2, 4, 6) for f-f transitions of Er3+ ions as well as transition probabilities, branching ratios, radiative lifetimes, and peak cross-sections for stimulated emission of each band were determined. The concentration effect on the intensities is analyzed. The optical properties of the fluoroindate glasses doped with Er3+ ions are compared with those of other glasses described in the literature. © 1995.

A simplified method for determining the high frequency induction motor equivalent electrical circuit parameters to be used in EMI effect

The aim of this paper is to present a simple method for determining the high frequency parameters of a three-phase induction motor to be used in studies involving variable speed drives with PWM three-phase inverters, in which it is necessary to check the effects caused to the motor by the electromagnetic interference, (EMI) in the differential mode, as well as in the common mode. The motor parameters determination is generally performed in adequate laboratories using accurate instruments, such as very expensive RLC bridges. The method proposed here consists in the identification of the motor equivalent electrical circuit parameters in rated frequency and in high frequency through characteristic tests in the laboratory, together with the use of characteristic equations and curves, shown in the references to be mentioned for determining the motor high frequency parasite capacitances and also through system simulations using dedicated software, like Pspice, determining the characteristic waveforms involved in the differential and common mode phenomena, comparing and validating the procedure through published papers [01].

Analysis of localized muscle fatigue in elderly women with and without a history of falls using electromyographic signal frequency parameters

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

Dielectric properties of Sr0.75Ba0.25Nb 2O6 thin films: Bias field, frequency and temperature dependence

Ferroelectric strontium barium niobate solid solutions had received great attention due to their excellent pyroelectric, electrooptic and photorefractive properties. Furthermore, they usually also present very interesting phase transition characteristics. In this work, polycrystalline single phase Sr 0.75 Ba 0.25 Nb 2 O 6 thin films were prepared by a hybrid chemical method and deposited on Pt/Ti/SiO 2 /Si substrates. The temperature dependence of dielectric constant was measured at different frequencies and bias field levels. The presence of two dielectric dispersion regions with relaxor characteristics was observed at distinct temperature ranges, corresponding to the ferro-paraelectric and to a structural phase transition at low temperatures, respectively. A specific dielectric dispersion region, associated with an incommensurate superstructure frequently observed in bulk samples, was not observed in this films probably due to their small grain sizes. © 2002 Taylor & Francis.

Characterization of the patellofemoral pain syndrome by frequency parameters of EMG signal

Patellofemoral pain syndrome (PFPS) is the most frequent complaint in orthopedic clinics; although, its etiology remains unclear [Bolgla, 2010; Felicio, 2011]. Trying to understand its causes has been used time analysis of electromyography (EMG), but this method shows controversies. The aim of this study was to apply a method of processing the EMG signal in the frequency domain of the vastus lateralis (VL) and vastus medialis (VM) muscles for the characterization of PFPS.

Source populations in coastal crabs: parameters affecting egg production

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

On determining spectral parameters, tracking jitter, and GPS positioning improvement by scintillation mitigation

A method of determining spectral parameters p (slope of the phase PSD) and T (phase PSD at 1 Hz) and hence tracking error variance in a GPS receiver PLL from just amplitude and phase scintillation indices and an estimated value of the Fresnel frequency has been previously presented. Here this method is validated using 50 Hz GPS phase and amplitude data from high latitude receivers in northern Norway and Svalbard. This has been done both using (1) a Fresnel frequency estimated using the amplitude PSD (in order to check the accuracy of the method) and (2) a constant assumed value of Fresnel frequency for the data set, convenient for the situation when contemporaneous phase PSDs are not available. Both of the spectral parameters (p, T) calculated using this method are in quite good agreement with those obtained by direct measurements of the phase spectrum as are tracking jitter variances determined for GPS receiver PLLs using these values. For the Svalbard data set, a significant difference in the scintillation level observed on the paths from different satellites received simultaneously was noted. Then, it is shown that the accuracy of relative GPS positioning can be improved by use of the tracking jitter variance in weighting the measurements from each satellite used in the positioning estimation. This has significant advantages for scintillation mitigation, particularly since the method can be accomplished utilizing only time domain measurements thus obviating the need for the phase PSDs in order to extract the spectral parameters required for tracking jitter determination.

Influence of design parameters on linear induction motor end effect

In this paper, a factor referred to as k(f) for linear induction motor end effect analysis is presented. The mathematical model takes into account the longitudinal entry end effect. The entry end effect produces considerable distortion in magnetic field distribution. It is shown how this influence is derived from the machine-developed force that is calculated through the application of the I-D theory. The k(f) factor establishes the relationship between the longitudinal end effect and machine parameters, mainly the number of magnetic poles, secondary resistivity, and frequency.

Photopyroelectric spectroscopy of polyaniline films

Photopyroelectric spectroscopy (PPES), in the 400 < lambda < 900 nm wavelength range, was used to study thermal properties of differently doped polyaniline (PAN) films. The photopyroelectric intensity signal V-n(lambda) and its phase F-n(lambda) were independently measured, as well as the intensity V-n(f) and the phase F-n(f) (f being the chopping frequency) for a given A of the saturation part of the PPES spectrum. Equations of both the intensity and the phase of the PPES signal, taking into account the thermal and the optical characteristics of the PAN films and the pyroelectric detector, were used to fit the experimental results. From the fittings we obtained, with great accuracy, the values of thermal conductivity k and thermal diffusivity coefficient a of PAN films of different doping degrees. It was observed that, in contrast with the strong doping-dependence of the electrical conductivity, the thermal parameters of PAN films remained practically unchanged under doping. This apparent discrepancy is explained by the granular metal model of doped PAN. (C) 2000 John Wiley & Sons, Inc.