Algunos aspectos del habla del barranco de las Cinco Villas

En número dedicado a: Avila: Valle del Tiéta

Control de fuerza en actuadores hidráulicos mediante válvula de alivio proporcional

El control de fuerza tratado en el presente trabajo es aplicado en actuadores hidráulicos mediante una válvula de alivio proporcional. Inicia con una revisión bibliográfica sobre algunas aplicaciones industriales y artículos de carácter investigativo. De acuerdo con ciertas necesidades académicas y los elementos disponibles en el Laboratorio de Sistemas Dinámicos, se optó por el modelo de control de fuerza por medio de una válvula proporcional de alivio. Dada la importancia de las válvulas proporcionales se hizo necesario realizar la caracterización y verificación del comportamiento de este componente, con el fin de evaluar su condición de funcionamiento. Posteriormente se adicionaron los demás elementos necesarios para completar el sistema y se estableció la comunicación e interacción de las señales presentes, obtenidas mediante un módulo de adquisición de datos (NI-USB 6008). El tratamiento de las señales y el control sobre la válvula proporcional de alivio se efectuó mediante el software LabVIEW, previa simulación del sistema en Matlab y la retroalimentación de la planta fue implementada mediante una celda de carga que registra la fuerza ejercida por el actuador; concluyendo con ello la implementación del control de fuerza en cilindros hidráulicos

On the onset of surface wind drift at short fetches as observed in a wind wave flume

International audienceOcean surface drift is of great relevance to properly model wind waves and specially the early stages of surfacewaves development and ocean-atmosphere fluxes during incipient wind events and storms. In particular, wavemodels are not so accurate predicting wave behaviour at short fetches, where wind drift onset might be veryimportant. The onset of surface drift induced by wind and waves is being studied through detailed laboratorymeasurements in a large wind-wave flume. Wind stress over the water surface, waves and surface drift aremeasured in the 40m long wind-wave tank at IRPHE, Marseille. While momentum fluxes are estimated directlythrough the eddy correlation method in a station about the middle of the tank, they provide reference informationto the corresponding surface drift onset recorded at rather short non-dimensional fetches. At each experimentalrun very low wind was on (about 1m/s) for a certain period and suddenly it was constantly accelerated to reachabout 13 m/s (as well as 8 and 5 m/s during different runs) in about 15 sec to as long as 600 sec. The windwas kept constant at that high speed for 2 to 10 min, and then suddenly and constantly decelerate to 0. Surfacedrift values were up to 0.5 cm/s for the highest wind while very distinctive shear was detected in the upper 1.5cm. Rather linear variation of surface drift was observed with depth. Evolution of the surface drift velocity isanalysed and onset behaviour is addressed with particular emphasis in accelerated winds. This work representsa RugDiSMar Project (CONACYT 155793) contribution. The support from ANUIES-ECOS M09-U01 project,CONACYT-187112 Estancia Sabática, and Institute Carnot, is greatly acknowledged

A reduced-order model for real-time NMPC of ethanol steam reformers

One of the approaches to green energy of interest in recent years is through the use of hydrogen technologies in which the waste product of combustion is water rather than carbon dioxide, nitrous oxides, and other pollutants generated by the burning of hydrocarbon fuels. Ethanol steam reformers is one of the primary technologies with the potential to generate hydrogen efficiently and reliably. This article investigates the design of nonlinear optimal feedback control systems for ethanol steam reformers based on mechanistic models described by a system of nonlinear partial differential-algebraic equations, aka singular/descriptor systems. The mechanistic models are too complicated to simulate in real-time using the standard numerical discretization methods, much less to directly incorporate such models as nonlinear constraints into mechanistic model-based nonlinear model predictive control formulations. This article employs a rather sophisticated multivariate form of the method of characteristics to reformulate the nonlinear constraints into a much simpler form amenable to real-time control implementations.Peer ReviewedPostprint (author's final draft

Digital Image Processing Applied to Optical Measurements

Digital image processing is a useful tool that improves pictorial information for human interpretation and is mainly used for storage, transmission, and representation of different data. In this chapter, we want to introduce an optical technique which couples physical analysis with image processing for a measurement system. Optical methods were used to obtain the stress-strain relation by different invasive and noninvasive methods. This chapter talks about a novel noninvasive methodology to measure stress-strain evolution; this technique is based upon a single laser beam reflected on the cross section of ductile materials (steel and aluminum) while they are under a compression load. The way we measure one laser beam is by using the Gaussian beam propagation equations; we propose that the reflection area of the laser is going to change as the material surface area is compressed and we analyze these differences by using digital image processing. With this technique we are able to construct a stress-strain diagram

Genetic and morpho-physiological differentiation in a limpet population across an intertidal gradient

Marine organism adaptive capacity to different environmental conditions is a research priority to understand what conditions are important in structuring the spatial distribution of natural populations. In this context, this study evaluates whether potential differences in Siphonaria lessonii morphology (size and shell shape) and physiology (water loss regulation) at different shore heights are linked to genetically distinguishable individuals. To achieve this goal, we compared size-frequency distribution, morphometric, and genetic data (ISSR-PCR technique) of S. lessonii from the upper, middle and lower shore. We complemented these field samplings with laboratory experiments on water loss and mortality. Genetic analysis showed different genetic composition for individuals from the upper and lower shore. This pattern was accompanied by morpho-physiological variations: the upper shore had fewer small limpets, lower shell shape dispersion (with a morphotype characterized by a higher shell), and less water loss and mortality related to air exposure than the lower shore. The results reported herein support the idea that the extreme and unpredictable conditions of the upper shore may impose strong selection pressure on its inhabitants, leading to considerable morpho-physiological differentiation consistent with different genetic composition. This probably plays an important role in structuring the spatial distribution of natural S. lessonii populations with a possible effect on size-structure distribution.Fil: Nuñez, Jesus Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Fernandez Iriarte, Pedro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Ocampo, Emiliano Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Madrid, Enrique. Universidad Nacional de Mar del Plata; ArgentinaFil: Cledón, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

LA NECESIDAD DE FOMENTAR LA EMPRESA SOCIAL Y SU PRÁCTICA EN LA CARRERA DE ADMINISTRACIÓN DE EMPRESAS (UNP).

Esta revisión tiene por objeto dar a conocer una nueva perspectiva del sector empresarial denominada Empresa Social y la necesidad fomentarlo en la carrera de Administración de Empresas (UNP), limitándose a las teorías de varios autores que realizaron investigaciones relacionados al tema en los últimos diez años y relacionándolo con los documentos institucionales de la Facultad de Ciencias Contables, Administrativas y Económicas, como ser resultado de cuestionarios y encuestas aplicadas a estudiantes y egresados, realizado por el comité de resultado e impacto de la mencionada institución, considerando que esta actividad empresarial tiene como principal fin buscar beneficios para la comunidad, por tanto, es oportuno que la Institución Educadora de futuros empresarios, permita producir proyectos sociales, investigaciones de posibles soluciones a los problemas actuales, que de esta manera se genere emprendimientos y se desarrolle las habilidades, finalmente no solo se adquiere beneficios comunitarios, sino que además el estudiante se prepara para los nuevos desafíos, razón por la cual se concluye la necesidad de realizar una combinación de teorías con prácticas a través de programas de desarrollo de proyectos con acompañamiento de la Facultad.The aim of this review is to present a new perspective of the business sector called Social Enterprise and the need to promote it in the career of Business Administration (UNP), limited in the theories of several authors who did research related to the subject in the last ten years and relating it to the institutional documents of the Facultad de Ciencias Contables Administrativas y Económicas, considering that this business activity has as its main goal to seek benefits for the community, therefore, it is opportune that the Educating Institution of future entrepreneurs, allows to produce social projects, investigations of possible solutions to the current problems, which in this way generates ventures and skills are developed, finally not only community benefits are acquired, but also the student is prepared for new challenges, which is why the need to combine theories with practices through project development programs is concluded with accompaniment of the Faculty

On the early stages of wind-wave generation under accelerated wind conditions

International audienceWhen wind starts to blow, a momentum transfer initiates through the air-water interface generating ocean wave. This transfer is usually characterized in terms of the drag coefficient, CD, but its dependency with wind speed still presents remarkable scatter in the experimental studies. Besides, Babanin and Makin (2008) found that gustiness were responsible to the most distant outliers in drag coefficient values. Also, several studies showed the influence of the sea state and wave age in the roughness and drag coefficient behavior (Smith et al. 1992; Donelan et al. 1993; Drennan 2003). Most of the past studies of wind-waves generation considered uniform and stationary wind speeds. However, in open field it is common to have conditions of wind blowing with a certain acceleration before the constant wind condition is reached. In order to study the early stages of the generation of waves under accelerated wind conditions, a total of five experiments with a characteristic wind speed acceleration were conducted in a large wind-wave facility at the Institut Pytheas (Marseille-France). Momentum fluxes were estimated from hot wire anemometry and, the free surface displacement was measured along the channel tank by resistance and capacitance wire probes. High resolution wind speed and water elevation measurements were acquired at a high resolution rate. During experiments the wind speed was increased with a constant acceleration over time, reaching a constant maximum intensity of 13 m/s. It was observed that during accelerated wind conditions, drag coefficient values depends on the degree of development of the flow regime in the air section and on wave field generation and evolution. The acceleration of wind speed has a direct influence on water surface roughness and water wave evolution in time and in space

Abono orgánico elaborado con lodo residual y estiércol equino a través de vermicomposteo: una propuesta como mejorador de suelos

Se elaboró un abono orgánico con estiercol equino y lodo residual y diferentes mezclas de estos, y la que tuvo los mejors resultados como mejorador de suelos fue la relación 70:30 estiercol equino-lodo residual, siendo medida por diferentes parametros físicos, químicos y metales pesados.Las actividades humanas producen toneladas de residuos sólidos orgánicos que causan problemas al ambiente, como la contaminación de suelo, agua y mantos freáticos. Ante esto, se han desarrollado estrategias como el vermicomposteo, proceso de estabilización de residuos sólidos orgánicos. El presente estudio tiene como objetivo probar mezclas de lodo residual y estiércol equino en diferentes porcentajes, por medio de vermicomposteo, para conocer su estabilidad y proponerlo como mejorador de suelo. Para su elaboración se utilizaron cuatro porcentajes de estiércol equino y lodo residual: E100, E85-LR15, E70-LR30 y E55-LR45 y se dio un seguimiento durante 90 días bajo condiciones de invernadero. El producto mostró disminución gradual en el porcentaje de C orgánico, relación C:N y pH. Se incrementó el contenido de N total a los 30 días y la conductividad eléctrica a los 75 días. El P aumentó para E70-LR30 (57.3 ± 8.3 mg/kg a 1369.8 ± 114.8 mg/kg) al final. A los 45 días se alcanzó la estabilidad de las vermicompostas en cuanto a la relación C:N: E100 (11.4); E85-LR15 (10.8); E70-LR30 (12.6) y E55-LR45 (11.2). La mejor relación es E70-LR30, ya que presenta un balance en el aporte de N y C, la concentración de metales pesados disminuyó para Cu, Zn, Ni y Cd, además el pH que presentó (7.24 ± 0.1) fue neutro, la concentración de P se incrementó considerablemente y el número de lombrices fue mayor (1790) con respecto a los otros tratamientos, por lo que esta relación es adecuada para su uso como abono orgánico

Performance of compliant mechanisms applied to a modified shape accelerometer of single and double layer

Accelerometers are widely used in several mechanisms of high sensitivity. They are employed for example in tilt-control in spacecraft, inertial navigation, oil exploration, seismic monitoring, etc. In order to improve the sensitivity of the measurements, implementation of Displacement-amplifying Compliant Mechanisms (DaCMs) in a capacitive accelerometer have been reported in the literature. In this paper, a system composed of two elements; capacitive accelerometer with extended beams (CAEB) and a DaCM geometry, of single and souble layer, are analysed. Three materials were considered, in the case, for the second layer. The DaCM implementation improves the operation frequency and displacement sensitivity, under different proportions, at the same time. Furthermore, three sweeps were performed: a range of thickness from 25 µm up to 30 µm (to determine the appropriate silicon mass value, using SOI technology), a range of second layer thickness (to choose the more appropriate material and its thickness) and a range of gravity values (to determine the maximum normal stress in the beams, which defines the superior value of the g operation range). The in-plane mode (y-axis) was considered in all analysed cases. This characterization was developed using the Finite Element Method. Structural and modal analysis responses were under study