Jaime Gutierrez

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Providing a stable horizon on endoscopic images especially in non-rigid endoscopic surgery (particularly NOTES) is still an open issue. Image rectification can be realized with a tiny MEMS tri-axial inertial sensor that is placed on the tip of an endoscope. By measuring the impact of gravity on each of the three orthogonal axes the rotation angle can be(More)
Recent research in wireless power transfer (WPT) using resonant inductive coupling has demonstrated very high efficiencies (above 40%) at large distances compared to the antenna dimensions, which has exponentially increased the number of potential applications of WPT. Since resonant inductive coupling is a very multidisciplinary field, different approaches(More)
A voltage quality index (VQI) is proposed for evaluation of the voltage quality aspects (QAs) of three-phase voltage signals: instantaneous frequency-deviations, total harmonic distortion and instantaneous symmetrical components. A VQI in the range between 0 to 1 is defined and measured. Accurate measurement of these Qas and VQI are obtained with a virtual(More)
The Fourier transform usually has been used in the past for analysis of stationary and periodic signals. Its interest is the knowledge of spectral components existing in a waveform; it doesn't matter the moment where they happen. However, when the time localization of the spectral components is needed, the Wavelet Transform (WT) can be used to obtain the(More)
The non-linear nature of the human visual response to achromatic contrast is a key element to improve the performance in achromatic image coding. Expressing transform coefficients in the appropriate contrast units is relevant when some particular non-linear processing hasto be applied. In the achromatic case, the use of non-linear psychophysical models is(More)
In the past the Fourier transform usually has been used for analysis of non-stationary signals, if interested in what the spectral components exist in the signal, and not interested where they occur. However, if this information is needed, i.e., if we want to know in order to analyze the transients, which spectral component occur at what interval of time,(More)
While the common term for describing the harmonic content and the unbalanced loading of the three-phase supply is power quality, it is actually the quality of the voltage that is being addressed in most cases. The power supply system can only control the quality of the voltage; it has no control over the currents that particular loads might draw. Therefore,(More)
—— According to the target of minimal line losses and a power factor equal to one, the present work studies two concepts of instantaneous compensation of nonactive current which are generally applied to polyphase systems. The analysis is defined both on the basis of the instantaneous value concept, for arbitrary voltage and current waveforms, and on the(More)
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