Sistema de Adquisición de Señales SEMG para la Detección de Fatiga Muscular / SEMG Signal Acquisition System for Muscle Fatigue Detection

Resumen Este trabajo presenta el desarrollo de un sistema de adquisición y procesamiento de señales mioeléctricas superficiales o SEMG. El sistema propuesto adquiere las señales SEMG de la superficie de la piel utilizando electrodos superficiales de AgCl. El sistema tiene una etapa de amplificación y de filtrado por hardware para eficientar el tiempo de proceso. Se desarrolló un software para procesar por transformada de Fourier la señal SEMG amplificada y filtrada. A diferencia de otros sistemas de adquisición de señales biológicas que son desarrollados para terapia o rehabilitación, este sistema está pensado para ser usado para el control de brazos robóticos, por ello el software desarrollado mide la fatiga utilizando parámetros como el corrimiento de la frecuencia media instantánea y la densidad espectral de potencia de la señal SEMG.

Abstract This paper presents the development of a system for acquiring and processing of surface myoelectric signals or SEMG. The proposed system acquires signals SEMG skin surface using AgCl surface electrodes. The system has an amplification step and hardware filtering to streamline the processing time. Developed software for processing the Fourier transform SEMG amplified and filtered signal. Unlike other systems for acquisition of biological signals, which are developed for therapy or rehabilitation, this system is intended to be used for the control of robotic arms, so the software performs the measurement of fatigue using parameters like bleed average frequency and instantaneous power spectral density of the signal SEMG.

Oil oxidation in corn flour from grains processed with alkaline cooking by use of peroxide value, UV and FTIR.

The objective of this work was to evaluate the effect of alkaline cooking on the oxidative stability of oil in corn flour. A central composite design was used to study the combined effect of lime concentration (%) and steep time (h) on peroxide value (PV); specific extinction coefficients at 232 and 270 nm (K232 and K270); and FTIR absorbance at 3009 cm(-1), 3444 cm(-1), and 3530 cm(-1) in oils from corn flour obtained by alkaline cooking. The results indicate that lime concentration and steep time affected the PV, K232, and K270. A decrease of 2.56 % was observed in the IR absorption bands, corresponding to the polyunsaturated fatty acids. The FTIR spectra also showed absorption bands related to the secondary oil oxidation products.