3,227 research outputs found
Proyecto de innovación educativa: límite y continuidad
Se explica un proyecto sencillo de innovación educativa para introducir de manera intuitiva la caracterización épsilon-delta de límite a estudiantes de bachillerato
La renovación de la enseñanza de la geografía en la EGB (1970-1984). Nuevos proyectos y viejos problemas.
Sin resume
Manual para el mantenimiento de carreteras
Este proyecto pretende elaborar un estudio, que permita de alguna manera organizar y estandarizar las labores que se involucran en la conservación de carreteras, teniendo en cuenta los diferentes tipos de mantenimiento de acuerdo con la naturaleza de cada una de las actividades. El problema del cual se ocupa este trabajo se formula de la siguiente manera: ¿cuáles son los criterios y parámetros que determinan la necesidad de elaborar un manual de mantenimiento de carreteras teniendo en cuenta las actividades que componen los diferentes tipos de mantenimiento vial? El objetivo general se centra en el análisis de las necesidades de clasificar, para poder programar, de manera general, las diferentes actividades componentes del mantenimiento de carreteras, para presentar un manual de ejecución y control de las diferentes actividade
DCOPF Contingency Analysis Including Phase Shifting Transformers
This work deals with a new formulation for the Direct Current Optimal Power Flow (DCOPF) including the corrective actions related to the phase shifting transformers. The formulation is based on the outage of generators and/or branches modelled as fictitious injections of active power. The inclusion of the sensitivities of the phase shifting transformer with respect to the injected powers is one of the novelties of this paper. By including the fictitious injections in the optimization problem, the injections are adjusted to the post-contingency state as a consequence of the corrective actions carried out by the DCOPF to bring the system back to its normal state. Consequently, when the analysis of contingencies is performed, the classical topological analysis and the subsequent analyses are avoided with this approach. The DCOPF includes as corrective control variables the rescheduling of active power generations, phase shifting transformers and, if required, permitted load shedding. The IEEE-RTS of 24 buses is used as benchmark network to assess the properties of the proposed approach.Spanish Ministry of Science and Innovation and Cooperation (Spain) ENE2011-24137Spanish Ministry of Science and Innovation and Cooperation (Spain) ENE2011-27984Junta de Andalucía PO11-TEP741
Conventional Industrial Robotics Applied to the Process of Tomato Grafting Using the Splicing Technique
Horticultural grafting is routinely performed manually, demanding a high degree of concentration and requiring operators to withstand extreme humidity and temperature conditions. This article presents the results derived from adapting the splicing technique for tomato grafting, characterized by the coordinated work of two conventional anthropomorphic industrial robots with the support of low-cost passive auxiliary units for the transportation, handling, and conditioning of the seedlings. This work provides a new approach to improve the efficiency of tomato grafting. Six test rates were analyzed, which allowed the system to be evaluated across 900 grafted units, with gradual increases in the speed of robots work, operating from 80 grafts/hour to over 300 grafts/hour. The results obtained show that a higher number of grafts per hour than the number manually performed by skilled workers could be reached easily, with success rates of approximately 90% for working speeds around 210–240 grafts/hour
Simple analysis and design of a new leaky-wave directional coupler in hybrid dielectric-waveguide printed-circuit technology
This paper presents a new theory to analyze and design a novel leaky-wave coupler based on a hybrid dielectric-waveguide printed-circuit technology. The analysis theory is based on a combined method of moments (MoM) geometrical optics (GO) technique, which makes use of the leaky mode complex propagation constant. This MoM-GO approach allows to easily obtain the response of the coupler, and to illustratively understand the working mechanism of the proposed structure. A coupler is designed to work at 5.5 GHz. Leaky mode results are compared with three-dimensional finite-element method simulations, showing the validity and accuracy of the new theory developed. This novel directional coupler presents interesting advantages when compared to previous wave couplersThis work was supported in part under Spanish National Project ESP2001-4546-PE and Spanish National Project TEC2004-04313-C02-02-TCM and under the Regional Séneca Project 2002PB/4/FS/02
Professional Certifications of a University Master’s Degree and Employability: Impact on Students’ Perception
[Abstract]: Professional certifications represent for many university degrees, especially postgraduate degrees, a recognition of their
academic quality and the future employability of the graduates. This article contributes to the analysis of the impact of external
accreditations on students’ perception of employability and satisfaction. We offer a case of study, a Master of Science (MSc) in
Banking and Finance that became the first academic degree in Spain to obtain the two professional accreditations required for
employees in financial institutions since 2019. A survey to a sample of students who graduated two academic years before and two
years after the MSc was recognised is used to measure students' motivations for enrolment and satisfaction. The results provide
significant evidence that professional accreditation became a key motivation for students to enrol the master, is associated with a
more diverse geographical origin of students, and students highlight the higher quality and better coordination of the teaching staff.R&D+i Program Oriented to Society’s Challenges ; PID2019-106273RBI0
Sensitivity-based external equivalent for reliability assessment of subtransmission & distribution systems
It is well known that topology changes in a power system strongly influences the results of reliability assessment studies. Besides, it is obvious that the topology of an external system also affect the reliability of the internal system through changes on the power flows within the rest of the system, and hence, through changes on the tie lines. In order to properly model the interconnection between the internal network and the rest of the system, an adaptive external equivalent model, obtained from the sensitivity matrix between tie-linepower flows and injectedpowers, is proposed for reliability assessment studies.
The proposed technique has been applied to the IEEERTS, and test results show that the proposed methodology is suitable both for planning studies and for 24-hour-ahead reliability assessment studies.Spanish Ministry of Science and Innovation ENE2010-18867Spanish Ministry of Science and Innovation ENE 2007-63306Spanish Ministry of Science and Innovation ENE 2007-66072Ministry of Foreign Affairs and Cooperation A/030124/10Junta de Andalucía TEP-517
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