Browsing by Author "Vargas, Yolanda"

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    Elastic tensor stiffness coefficients for SLS Nylon 12 under different degrees of densification as measured by ultrasonic technique
    (EMERALD GROUP PUBLISHING LTD, 2008) Ramos Grez, Jorge; Amado Becker, Antonio; Yanez, Maria Jose; Vargas, Yolanda; Gaete, Luis
    Purpose - The purpose of this paper is to present results of an investigation, where the elastic tensor based on the engineering constants of sinterized Nylon 12 is characterized and is modeled considering a transversely isotropic behavior as a function of apparent density (relative mass density).
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    Ultrasound based measurements of sugar and ethanol concentrations in hydroalcoholic solutions
    (ELSEVIER SCI LTD, 2008) Sint Jan, Michael Van; Guarini, Marcelo; Guesalaga, Andrs; Perez Correa, J. Ricardo; Vargas, Yolanda
    Industrial automation is useful to reduce production costs and improve product quality. The wine industry has been increasingly adopting industrial automation seeking these objectives. In Chile, wineries have been lagging behind in embracing new technologies to control the fermentation process. In most cases, enologists decide control actions (cooling, heating, pumping over) based on off line periodic measurements. In this work we explore the applicability of ultrasound to measure the sugar and alcohol concentrations of hydroalcoholic solutions mimicking fermenting musts. Additionally, implementation issues such as the attenuation effect of bubbles and tank curvature are analyzed. We show that working at two sufficiently distinct frequencies, we can measure sugar and alcohol content simultaneously. Measurement resolution achieved for the wave time of travel translates to a better than 0.02% for both concentrations, depending on the container size. (c) 2007 Elsevier Ltd. All rights reserved,