4,554 research outputs found
Two Globally Convergent Adaptive Speed Observers for Mechanical Systems
A globally exponentially stable speed observer for mechanical systems was
recently reported in the literature, under the assumptions of known (or no)
Coulomb friction and no disturbances. In this note we propose and adaptive
version of this observer, which is robust vis--a--vis constant disturbances.
Moreover, we propose a new globally convergent speed observer that, besides
rejecting the disturbances, estimates some unknown friction coefficients for a
class of mechanical systems that contains several practical examples
Avances y desafiÌos de la formacioÌn investigativa en la carrera de PedagogiÌa de la Universidad PoliteÌcnica Salesiana de Ecuador
El presente ensayo es una aproximacioÌn inicial a la formacioÌn investigativa de la Carrera de PedagogiÌa de la Universidad PoliteÌcnica Salesiana de Ecuador (UPS) y fue elaborado como una exigencia del curso âProblemas sociales de la ciencia y la tecnologiÌaâ impartido en la ciudad de la Habana como parte del doctorado en Ciencias PedagoÌgicas que el autor se encuentra cursando. El enfoque teoÌrico utilizado es el del campo Ciencia, TecnologiÌa y Sociedad (CTS) a traveÌs del cual se procura evidenciar las interrelaciones entre la investigacioÌn, la ciencia, la tecnologiÌa y el contexto histoÌrico-social que configuran este complejo entramado
La Universidad PoliteÌcnica Salesiana en el proceso de redisenÌo curricular del consejo de educacioÌn superior del Ecuador
La sociedad ecuatoriana sigue con marcado intereÌs el proceso de transformacioÌn de la matriz productiva auspiciada por el Gobierno actual. El Plan Nacional de Desarrollo ha senÌalado la pauta para ello y se espera que en el mediano plazo se vean los efectos de esta iniciativa. Un sector estrateÌgico para este cambio lo constituye la educacioÌn superior, la misma que bajo las directrices del Consejo de EducacioÌn Superior (CES) empezoÌ, desde hace alguÌn tiempo atraÌs, el redisenÌo curricular de sus ofertas educativas. La Universidad PoliteÌcnica Salesiana (UPS) asumioÌ de manera entusiasta y ciÌvica este reto, pero en el camino se ha encontrado con algunos escollos que rebasan las dificultades normales que se pueden presentar en este tipo de esfuerzos y que por sus repercusiones generan un cierto nivel de preocupacioÌn e incertidumbre y que deben ser analizados con el filtro de la teoriÌa pedagoÌgica y los valores que guiÌan la praÌctica educativa de nuestra institucioÌn
The Legal Implications of Anti-LGBTQ+ Curriculum Laws
Last March 2022, Floridaâs Governor Ron DeSantis passed and enacted the Parental Rights in Education Act, which then became known as the infamous âDon\u27t Say Gayâ bill. The bill bans instruction on sexual orientation and gender identity âbefore the 4th grade and requires such instruction to be âage-appropriate or developmentally appropriate.â The language of the bill itself is vague and broad and doesnât provide clarity about the lawâs compliance with non-discrimination and first amendment rights. Critics argue that the statute doesnât define the meaning of âclassroom instructionâ or what constitutes âage-appropriateâ or âdevelopmentally appropriateâ instruction, which leaves questions regarding the scope of the law. The âDon\u27t Say Gayâ bill was based on the idea that parents have the fundamental right to make decisions regarding when and how their children should be introduced to certain topics, specially LGBTQ+ rights and history. The law, by default, stigmatizes the identities of LQGBTQ+ students, teachers and administrators and encourages them to hide who they are out of fear of retaliation by intolerant parents. Furthermore, the âDon\u27t Say Gayâ bill inherently prevents teachers from educating children productively and introducing them to topics that are essential to their development.
This post was originally published on the Cardozo Journal of Equal Rights and Social Justice website on April 3, 2023. The original post can be accessed via the Archived Link button above
Improving the Performance of Low Voltage Networks by an Optimized Unbalance Operation of Three-Phase Distributed Generators
This work focuses on using the full potential of PV inverters in order to improve the efficiency of low voltage networks. More specifically, the independent per-phase control capability of PV three-phase four-wire inverters, which are able to inject different active and reactive powers in each phase, in order to reduce the system phase unbalance is considered. This new operational procedure is analyzed by raising an optimization problem which uses a very accurate modelling of European low voltage networks. The paper includes a comprehensive quantitative comparison of the proposed strategy with two state-of-the-art methodologies to highlight the obtained benefits. The achieved results evidence that the proposed independent per-phase control of three-phase PV inverters improves considerably the network performance contributing to increase the penetration of renewable energy sources.Ministerio de EconomĂa y Competitividad ENE2017-84813-R, ENE2014-54115-
Yielding of rockfill in relative humidity-controlled triaxial experiments
The final publication is available at Springer via http://dx.doi.org/10.1007/s11440-016-0437-9The paper reports the results of suction controlled triaxial tests performed on compacted samples of two well graded granular materials in the range of coarse sand-medium gravel particle sizes: a quartzitic slate and a hard limestone. The evolution of grain size distributions is discussed. Dilatancy rules were investigated. Dilatancy could be described in terms of stress ratio, plastic work input and average confining stress. The shape of the yield locus in a triaxial plane was established by different experimental techniques. Yielding loci in both types of lithology is well represented by approximate elliptic shapes whose major axis follows approximately the Ko line. Relative humidity was found to affect in a significant way the evolution of grain size distribution, the deviatoric stress-strain response and the dilatancy rules.Peer ReviewedPostprint (author's final draft
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