Abstract A microstrip leaf-shaped printed monopole antenna bioinspired on the Inga marginata leaves is presented in this paper for UWB applications. A parametric study of the proposed antenna bioinspired geometry was conducted in order to verify their resonant properties. The antenna was designed with a rectangular slitted ground plane for impedance matching and fabricated on inexpensive glass fiber substrate and fed by a 50 Ω microstrip line. Numerical and experimental results were obtained. The results show an impedance bandwidth superior to 10.26 GHz, greater than the bandwidth considered UWB (7.5 GHz). Antenna dimensions were optimized with the computer program Ansys Designer® used to simulate the electromagnetic behavior of the antennas by the method of moments.

Abstract Introduction The present work aims to develop statistical models for the psychoacoustic behavior of human beings in lateralization judgments of binaural acoustic stimuli, as a function of Interaural Time Delay (ITD) and Interaural Amplitude Difference (IAD) for several Sensation Levels (SL). Such models intend to contribute to a deep comprehension of the perception or recognition mechanism which permits listeners to decide whether a source of a sound is located on the right or on the left side of their medial plane. Methods Numerous lateralization judgments are accomplished through a computer controlled experiment set-up in order to investigate the transduction mechanism beneath them. The statistical treatment of the psychoacoustic data obtained has been performed by Two and Three Factors – Probit (Probability Unit) Analysis. Results The Probit Analysis makes it possible to obtain the model coefficients and to fit ‘Probit Planes and Surfaces’ to the experimental data in order to study and predict the simultaneous effects produced by ITD and IAD in the listeners’ psychoacoustic perceptions at several Sensation Levels (SL). Conclusion The approach used here is appropriate for the analysis of this kind of binary response and it also offers a simple way to obtain psychophysical responses that can be related to neurophysiological phenomena. It is argued that this fact may lead to another way to access neural information through psychoacoustic experiments, without needing invasive methods.

INTRODUCTION: The aim of this work is to present a physical implementation of a noninvasive methodology to analyze the directional sensitivity of human auditory system. A computer controlled experiment set-up has been designed and developed to study the behavior of human subjects under the presentation of interaural time delays and interaural amplitude differences for several sensation levels. METHODS: The proposed methodology comprises: the application of trains of low-pass filtered narrow pulses as acoustic binaural stimuli; the automatic, simultaneous and random variation of interaural time delays and interaural amplitude differences; the absence of human interference along the experimental sessions, except for the decision of the listener under test; the minimization of adaptation effects. RESULTS: Numerous lateralization judgments have been accomplished in order to investigate the transduction mechanism which allows deciding which side of subjects medial plane the source of binaural acoustic stimuli is located in. The behavior of decision time with the order of judgment, the sensation levels and the interaural differences in time and amplitudes has been analyzed. CONCLUSION: The noninvasive, reliable and automatic approach here presented allows obtaining psychophysical responses associated to the neuro-physiological phenomena underneath lateralization capability.

In this paper are presented some considerations about the performance of single wire earth return amorphous alloy core transformers in comparison with conventional silicon steel sheets cores transformers used in rural electric energy distribution network. It has been recognized that amorphous metal core transformers improve electrical power distribution efficiency by reducing transformer core losses. This reduction is due to some electromagnetic properties of the amorphous alloys such as: high magnetic permeability, high resistivity, and low coercivity. Experimental results obtained with some single-phase, 60 Hz, 5 kVA amorphous core transformers installed in a rural area electric distribution system in Northern Brazil have been confirming their superior performance in comparison to identical nominal rated transformers built with conventional silicon steel cores, particularly with regard to the excitation power and to the no-load losses.

In this paper are presented theoretical analysis and experimental results concerning the performance of toroidal cores used in current transformers. For most problems concerning transformers design, analytical methods are useful, but numerical methods provide a better understanding of the transformers electromagnetic behaviour. Numerical field solutions may be used to determine the electrical equivalent circuit parameters of toroidal core current transformers. Since the exciting current of current transformers alters the ratio and phase angle of primary and secondary currents, it is made as small as possible though the use of high permeability and low loss magnetic material in the construction of the core. According to experimental results presented in this work, in comparison with others soft magnetic materials, nanocrystalline alloys appear as the best material to be used in toroidal core for current transformers.