4,261 research outputs found
La eficiencia terminal en programas de licenciatura y su relación con la calidad educativa
Aún cuando la equidad sigue siendo el mayor reto del sistema educativo mexicano y que durante el siglo pasado el gobierno federal dedicó gran parte de sus esfuerzos a la expansión de dicho sistema, lo cierto es que la calidad de los servicios educativos no ha sido atendida con la misma intensidad. La calidad educativa abarca conceptos como el de pertinencia, cobertura, niveles de desempeño, eficacia y eficiencia y bajo este concepto, resulta fácilmente discernible concebir los problemas de baja eficiencia terminal, rezago académico y deserción como manifestaciones de una falta de calidad del proceso educativo. Se presentan los resultados de un estudio relacionado con dichos parámetros efectuado en una muestra conformada por cinco generaciones dentro del programa de Ingeniería Civil en la Universidad Autónoma de San Luis Potosí, a fin de identificar las causas relacionadas con la baja eficiencia terminal que de manera general afecta a nuestros programas. Se propone una serie de alternativas a fin de abatir dichos índices e incrementar la eficacia de los planes académicos, alternativas que se traducen en acciones tendientes a una mayor promoción de las carreras de ingeniería, modificaciones en los planes curriculares e incrementos en la efectividad de las tutorías individualizadas
Thermal and electrohydrodynamic plumes: a compartive study
This paper deals with self similar thermal and electrohydrodynamic (EHD) plumes. The former
arises from hot lines or points, whereas the latter arises when sharp metallic contours submerged in
non conducting liquids support high electrostatic potential, resulting in charge injection. Although
the motive force is buoyancy in one case and Coulomb force in the other, it is shown that the
solution for EHD plumes is the same as for thermal plumes in the limit of large Prandtl numbers.
We present the analysis of axisymmetric plumes for large values of Prandtl number, and this analysis
is subsequently applied to EHD plumes. The validity of the approximations for EHD plumes is
discussed in the light of experimental data.Ministerio de ciencia y tecnología PB93-118
Hypnos: a Hardware and Software Toolkit for Energy-Aware Sensing in Low-Cost IoT Nodes
Through the Internet of Things, autonomous sensing
devices can be deployed to regularly capture environmental and
other sensor measurements for a variety of usage scenarios.
However, for the market segment of stand-alone, self-sustaining
small IoT nodes, long term deployment remains problematic
due to the energy-constrained nature of these devices, requiring
frequent maintenance. This article introduces Hypnos, an open
hardware and software toolkit that aims to balance energy intake
and usage through adaptive sensing rate for low-cost Internetconnected IoT nodes. We describe the hardware architecture of
the IoT node, an open hardware board based on the Arduino
Uno form-factor packing the energy measurement circuitry, and
the associated open source software library, that interfaces with
the sensing node’s microcontroller and provides access to the
low-level energy measurements. Hypnos comes equipped with a
built-in, configurable, modified sigmoid function to regulate duty
cycle frequency based on energy intake and usage, yet developers
may also plug in their custom duty/sleep balancing function.
An experiment was set up, whereby two identical boards ran
for two months: one with the Hypnos software framework and
built-in energy balancing function to regulate sensing rate and
the other with fixed sensing rate. The experiment showed that
Hypnos is able to successfully balance energy usage and sensing
frequency within configurable energy ranges. Hereby, it increases
reliability by avoiding complete shutdown, while at the same time
optimizing performance in terms of average amount of sensor
measurements
On two-dimensional finite amplitude electro-convection in a dielectric liquid induced by a strong unipolar injection
The hydrodynamic stability of a dielectric liquid subjected to strong unipolar injection is numerically investigated. We determined the linear criterion Tc (T being the electric Rayleigh number) and finite amplitude one Tf over a wide range of the mobility parameter M. A noticeable discrepancy is shown for Tf between our numerical prediction and the value predicted by stability analysis, which is due to the velocity field used in stability analysis. Recent studies revealed a transition of the flow structure from one cell to two with an increase in T. We demonstrate that this transition results in a new subcritical bifurcationMinisterio de Ciencia y Tecnología FIS2011-25161Junta de Andalucía P10-FQM-5735Junta de Andalucía P09-FQM-458
Complex flow patterns at the onset of annular electroconvection in a dielectric liquid subjected to an arbitrary unipolar injection
We numerically investigated the annular electroconvection that takes place in a dielectric liquid lying between two concentric cylinder electrodes. A uniform injection of arbitrary strengths either from the inner or outer cylinder introduces free charge carriers into the system, and the resulting Coulomb force induces electroconvection. The problem is characterized by a linear instability that corresponds to the onset of flow motion. The linear stability criteria were determined from direct numerical results and by linear stability analysis, and the results obtained with the two approaches show an excellent agreement. We focused on the fully developed flow pattern in the finite amplitude regime. We observed very different flow motions that were highly dependent on the injection strength.Ministerio de Ciencia y Tecnología FIS2011-25161Junta de Andalucía P10-FQM-5735Junta de Andalucía P09-FQM-458
Chilean EFL teachers`perceptions of their working condition in the private, semi -private and public school systems
Tesis (Profesor de Inglés para la Enseñanza Básica y Media y al grado académico de Licenciado en Educación)This study followed a quantitative survey research design. The main purpose of the research was to explore Chilean English teachers’ perceptions of their working conditions, and compare the perceptions of teachers from the public, semi-private and private school systems. The data was collected by applying a questionnaire, a technique used in quantitative research. Sixty three teachers from forty six schools of the three educational sectors polled, answered the questionnaire using a 5-point Likert scale in order to express their perceptions regarding their working conditions. In the analysis process, the information collected was presented descriptively. In general, the participants showed positive perceptions concerning school environment and school support from their school authorities, but negative perceptions regarding salary, workload, time for non-instructional activities and society perceptions toward their profession.El presente estudio utilizó el diseño de encuesta cuantitativa. El propósito principal de nuestra investigación fue explorar las percepciones de los profesores de inglés chilenos acerca de sus condiciones laborales, y comparar estas percepciones de los profesores del sistema público, subvencionado y privado de la educación. La información fue recopilada a través de la aplicación de un cuestionario; técnica usada en el método cuantitativo de investigación. Sesenta y tres profesores de cuarenta y seis colegios de los tres sectores educacionales: público, subvencionado y privado, contestaron la encuesta usando la escala Likert del 1 al 5, de manera de obtener sus percepciones acerca de sus condiciones laborales. En el proceso de análisis, la información recolectada fue presentada descriptivamente. De manera general, los participantes demostraron percepciones positivas de acuerdo al clima laboral y el apoyo de las autoridades de los colegios; sin embargo, las percepciones fueron negativas acerca de su salario, carga laboral, tiempo para actividades extra curriculares y las percepciones de la sociedad acerca de la profesión docente
Electroconvection in a dielectric liquid between two concentric half-cylinders with rigid walls: Linear and nonlinear analysis
We study the linear stability and nonlinear behavior of the electroconvection between two concentric halfcylinders
with no-slip conditions on all boundaries. The no-slip condition makes impossible to apply the standard
modal approach. Hence, we apply a finite element technique similar to the one we have used in a previous
paper about the electroconvection in a rectangular enclosed domain. When compared to the classical problem of
electroconvection between two full concentric cylinders, the linear criterion is higher, due to the viscous shear
introduced by the lateral walls. As a consequence, the structure of the eigenmodes is very different. There is a
repulsion between modeswith the same symmetry, forcing pairs of modes to cross each other repeatedly. For inner
injection and small value of the ratio between the inner and outer radii the no-slip condition changes the nature
of the bifurcation from subcritical to supercritical, while it is always subcritical for outer injection. To understand
this behavior, we perform a modal analysis using the eigenfunctions obtained from the linear stability analysis
as modal basis. We show that the supercritical branch is originated by the nonorthogonality of the modes when
no-slip boundary conditions are imposed. These mechanism explains the previously unexplained appearance of
the supercritical branch in the enclosed rectangular configuration.Ministerio de Economía y Competitividad FIS2014-54539-
Onset of convection in a finite two-dimensional container due to unipolar injection of ions
This work addresses the stability of a two-dimensional plane layer of a dielectric liquid enclosed in wall
bounded cavities of different aspect ratios and subjected to unipolar injection of ions. Numerical simulations
have been conducted to investigate the effect of lateralwalls, especially in the development of the electroconvective
instability. It is found that an unexpected change of the bifurcation nature occurs for certain cavity aspect ratios.
We showthat above the linear stability threshold for the rest state a supercritical bifurcation arises. This bifurcation
takes place at a given value Tc1 of the parameter T (the electric Rayleigh number). Then, a second subcritical
bifurcation occurs at a second threshold Tc2, featuring a typical hysteresis loop with an associated nonlinear
criterion Tf , which is very characteristic of the Coulomb-driven convection. This behavior has been confirmed
by different numerical codes based on different numerical methods. The physical mechanism which leads to this
situation is analyzed and discussed. The evolution of the bifurcation diagrams with the aspect ratio of the cavity
is also provided and analyzed.Ministerio de ciencia y tecnología FIS2011-25161Junta de Andalucía P10-FQM-5735Junta de Andalucía P09-FQM-458
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