Family Dependence in SU(3)_C X SU(3)_L X U(1)_X models

Using experimental results at the Z-pole and atomic parity violation, we perform a chi-squared fit at 95% CL to obtain family-dependent bounds to Z_2 mass and Z-Z' mixing angle in the framework of SU(3)_C X SU(3)_L X U(1)_X models. The allowed regions depend on the assignment of the quark families in mass eigenstates into the three different families in weak eigenstates that cancel anomaliesComment: 14 pages, 2 figures, LaTeX2e; added references, added equations with electroweak corrections for section 4. Version to appear in Phys. Rev.

Quark mass hierarchy in 3-3-1 models

We study the mass spectrum of the quark sector in an special type I-like model with gauge symmetry $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$. By considering couplings with scalar triplets at large ($\sim TeV$) and small ($\sim GeV$) scales, we obtain specific zero-texture mass matrices for the quarks which predict three massless quarks ($u,d,s$) and three massive quarks ($c,b,t$) at the electroweak scale ($\sim$ GeV). Taking into account mixing couplings with three heavy quarks at large scales predicted by the model, the three massless quarks obtain masses at small order that depends on the inverse of the large scale. Thus, masses of the form $m_u \lesssim m_d < m_s \sim MeV$ and $m_{c,b,t} \sim GeV$ can be obtained naturally from the gauge structure of the model

A Simplified Electro-Mechanical Model of a DFIG-based Wind Turbine for Primary Frequency Control Studies

In recent years, world-wide power systems are experiencing a steadily growth of wind power penetration. A common concern in the operation of such systems is related to the frequency stability. Modern variable speed wind turbines have a limited capacity in providing ancillary services, such as fast-frequency response and primary frequency regulation. Recent developments in wind plant controllers allow performing active power control from all its units to respond to system frequency deviations. It is thus important to study the effects of the presence of these plants in the system frequency response. Existing detailed models of wind turbines are not suitable to this goal because their complexity makes them impractical for system-wide studies. This paper presents a simplified model of a wind turbine with Doubly-Fed Induction Generator specifically conceived for such studies, along with its validation with a detailed mode

Concepciones de práctica pedagógica de estudiantes con bajos desempeños, en la licenciatura en Pedagogía Infantil de la Universidad Tecnológica de Pereira

La presente investigación se centra en el estudio de las Concepciones de Práctica Pedagógica de las estudiantes con bajo desempeño, de Licenciatura en Pedagogía Infantil de la Universidad Tecnológica de Pereira. Se propone una investigación cualitativa de corte interpretativo, que permita identificar los discursos y las actuaciones de las estudiantes, a través de instrumentos como la entrevista semiestructurada, observación no participante y la historia de vida, desde las categorías de análisis: identidad, conceptualización y quehacer. Los resultados de la investigación permitieron describir las concepciones de las estudiantes de bajo desempeño, y así develar cuales son las dificultades en la transformación de sus prácticas, lo que podría servir de insumo para plantear propuestas de formación de docentes, en el programa de Licenciatura en Pedagogía infantil y en general a todos los programas de formación de licenciados, de tal manera que se puedan forman docentes reflexivos e innovadores.This research focuses on the study of the conceptions of teaching practice of students Children Pedagogy Education Degree from the University of Pereira poor performers in their teaching practice. We propose a cutting interpretive qualitative research to identify the speeches and actions of the students, through instruments such as semi-structured interviews, participant observation and life history, from the categories called identity, conceptualization and teaching work. The research results reveal conceptions allow the students and thus understand what are the difficulties in processing, which could serve as an input to make proposals for teacher training

Contribution of DFIG wind turbines to Primary Frequency Control

In recent years, worldwide power systems are experiencing a steadily growth in wind power penetration. A common concern in the operation of such systems is related to the frequency stability. Modern variable speed wind turbines have a limited capacity in providing ancillary services, such as: fastfrequency response and primary frequency regulation. This thesis aims at developing a new methodology for the analysis of frequency dynamics in largescale power systems with high level of wind energy share. Firstly, a simplified electromechanical model of a doubly fed induction generator (DFIG) based wind turbine has been proposed. In addition, a virtual inertia controller version of the optimized power point tracking method (OPPT) has been adapted for this kind of wind turbines. In this method, the maximum power point tracking curve (MPPT) is shifted to drive variations in the active power injection as a function of the grid frequency deviation, by exploiting the available inertial resources. The proposed methodology integrates the model in a primary frequency control scheme to assess the interaction with the rest of the plants in the power system

Planificación estratégica y mejora de la calidad en las universidades

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