El cuello de botella de Pepe

Pepe Botellas. Gustavo Álvarez Gardeazábal. Editorial Plaza y Janés. Bogotá, 1984

Razones y condiciones para el tránsito de la confrontación armada a la contienda democrática en Colombia

La lectura de los resultados de algunas encuestas sobre la opinión de los colombianos respecto al conflicto armado y al proceso de negociación con la guerrilla pone en evidencia que existen posiciones, que sometidas a un juicio más cuidadoso, son contradictorias desde el punto de vista ético y político

Redesigning engineering courses by introducing digital ink technology

© 2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.We applied the How People Learn framework (HPLf) in two different higher education contexts. On one hand, a first-year core course on Computer Technology, taught at the Computer Engineering Degree Program at Universitat Politècnica de València, Spain. On the other hand, two Food Chemistry related courses, taught at Universidad de las Américas Puebla, Mexico, as part of food engineering undergraduate and food science graduate programs. The goal of these works was to redesign studied courses at both universities from a lecture-based format to a "challenge-based" format by using Tablet PCs and digital ink. In order to support the studied approach, different inkenabled software tools were utilized. Class sessions were enhanced through the usage of Classroom Presenter, a penbased interaction system that supports the sharing of digital ink on slides between instructors and students. InkSurvey also allowed teachers to pose questions, receive instantly digital ink responses, and provide real-time formative feedback. Some other tools such as PDF Annotator and Ardesia helped instructors to review coursework and assignments and provide formative feedback as well. We studied our approach over the two last academic years by observing classes at both universities, obtaining selected student achievement indicators and conducting surveys with students and instructors.We acknowledge financial support from HEWLETT-PACKARD (HP), through the HP Technology for Teaching Higher Education Grant Initiative for Latin America for the project "High-Quality Learning Environments for Engineering Design: Using Tablet PCs and Guidelines from Research on How People Learn" as well as through the HP Catalyst Grant Initiative for the project “Critical Support Systems to Enhance the Development of 21st Century Expertise in Engineering Students: Using Tablet PCs and Associated Technologies, the Framework for 21st Century Learning, and Guidelines from Research on How People Learn”. Similarly, UPV group received an HP Technology for Teaching High Education Grant Program for Europe, Middle East and Africa in 2008: “Improving effective learning in a first-year Computer Engineering course by using mobile Tablet PC technology”.Benlloch-Dualde, J.; Buendía García, F.; Lemus Zúñiga, LG.; Cano Escribá, JC.; Gutiérrez Cuba, JV.; López-Malo, A.; Palou, E. (2013). Redesigning engineering courses by introducing digital ink technology. IEEE. https://doi.org/10.1109/FIE.2013.6684786

Influence of atmospheric conditions on the power production of utility-scale wind turbines in yaw misalignment

The intentional yaw misalignment of leading, upwind turbines in a wind farm, termed wake steering, has demonstrated potential as a collective control approach for wind farm power maximization. The optimal control strategy and the resulting effect of wake steering on wind farm power production are in part dictated by the power degradation of the upwind yaw misaligned wind turbines. In the atmospheric boundary layer, the wind speed and direction may vary significantly over the wind turbine rotor area, depending on atmospheric conditions and stability, resulting in freestream turbine power production which is asymmetric as a function of the direction of yaw misalignment and which varies during the diurnal cycle. In this study, we propose a model for the power production of a wind turbine in yaw misalignment based on aerodynamic blade elements, which incorporates the effects of wind speed and direction changes over the turbine rotor area in yaw misalignment. The proposed model can be used for the modeling of the angular velocity, aerodynamic torque, and power production of an arbitrary yaw misaligned wind turbine based on the incident velocity profile, wind turbine aerodynamic properties, and turbine control system. A field experiment is performed using multiple utility-scale wind turbines to characterize the power production of yawed freestream operating turbines depending on the wind conditions, and the model is validated using the experimental data. The resulting power production of a yaw misaligned variable speed wind turbine depends on a nonlinear interaction between the yaw misalignment, the atmospheric conditions, and the wind turbine control system

Influence of atmospheric conditions on the power production of utility-scale wind turbines in yaw misalignment

The intentional yaw misalignment of leading, upwind turbines in a wind farm, termed wake steering, has demonstrated potential as a collective control approach for wind farm power maximization. The optimal control strategy, and resulting effect of wake steering on wind farm power production, are in part dictated by the power degradation of the upwind yaw misaligned wind turbines. In the atmospheric boundary layer, the wind speed and direction may vary significantly over the wind turbine rotor area, depending on atmospheric conditions and stability, resulting in freestream turbine power production which is asymmetric as a function of the direction of yaw misalignment and which varies during the diurnal cycle. In this study, we propose a model for the power production of a wind turbine in yaw misalignment based on aerodynamic blade elements which incorporates the effects of wind speed and direction changes over the turbine rotor area in yaw misalignment. A field experiment is performed using multiple utility-scale wind turbines to characterize the power production of yawed freestream operating turbines depending on the wind conditions, and the model is validated using the experimental data. The resulting power production of a yaw misaligned variable speed wind turbine depends on a nonlinear interaction between the yaw misalignment, the atmospheric conditions, and the wind turbine control system.Comment: 37 pages, 15 figure

Small renal masses in Latin-American population : Characteristics and prognostic factors for survival, recurrence and metastasis - A multi-institutional study from LARCG database

To evaluate demographic, clinical and pathological characteristics of small renal masses (SRM) (≤ 4 cm) in a Latin-American population provided by LARCG (Latin-American Renal Cancer Group) and analyze predictors of survival, recurrence and metastasis. A multi-institutional retrospective cohort study of 1523 patients submitted to surgical treatment for non-metastatic SRM from 1979 to 2016. Comparisons between radical (RN) or partial nephrectomy (PN) and young or elderly patients were performed. Kaplan-Meier curves and log-rank tests estimated 10-year overall survival. Predictors of local recurrence or metastasis were analyzed by a multivariable logistic regression model. PN and RN were performed in 897 (66%) and 461 (34%) patients. A proportional increase of PN cases from 48.5% (1979-2009) to 75% (after 2009) was evidenced. Stratifying by age, elderly patients (≥ 65 years) had better 10-year OS rates when submitted to PN (83.5%), than RN (54.5%), p = 0.044. This disparity was not evidenced in younger patients. On multivariable model, bilaterality, extracapsular extension and ASA (American Society of Anesthesiologists) classification ≥3 were predictors of local recurrence. We did not identify significant predictors for distant metastasis in our series. PN is performed in Latin-America in a similar proportion to developed areas and it has been increasing in the last years. Even in elderly individuals, if good functional status, sufficiently fit to surgery, and favorable tumor characteristics, they should be encouraged to perform PN. Intending to an earlier diagnosis of recurrence or distant metastasis, SRM cases with unfavorable characteristics should have a more rigorous follow-up routine

El cultivo del caqui

En este libro se escribe del caqui en toda su amplitud, los mejores investigadores en las diferentes especialidades nos explican los resultados de la investigación y experiencias en fertirrigación, pies y variedades, sanidad vegetal, poda y postcosecha; acompañado y documentado de una amplia bibliografía de los investigadores de los principales países productores del mundo: China, Japón e Israel, e Italia, más que por su producción, por su continua y avanzada investigación. Este libro, fruto del trabajo de las diferentes líneas de investigación del producto, coordinada por el magnífico equipo de investigadores del IVIA, pone a disposición de la producción, postcosecha y comercialización todos los avances conocidos a nivel nacional e internacional

Hexágono '71 - dg

Trabajos plásticos: Edgardo Vigo. Juan Carlos García Palou. Eduardo Leonetti. Juan Carlos Romero.Centro de Arte Experimental Vig