Study of the efflux velocity induced by two propellers

Present analysis is related with seabed erosion caused during docking and undocking maneuvering. Twin propellers without rudder were studied using a physical model with a fixed clearance distance and three different rotating velocities. Experimental results were compared to theoretical expressions of the efflux velocity, axial velocity and finally maximum bed velocity. Efflux velocity equations overestimate the experimental results, whereas axial velocity computed using the Dutch method fits reasonably well the experimental data. However, when maximum bed velocity expressions are compared to experimental results, German method behaves better with an over estimation if a quadratic superposition of the single jets is used.Postprint (published version

Plan de marketing para posicionamiento de la bomba post-cosecha en el sector bananero

El presente Plan de Marketing para el Posicionamiento de la Bomba Postcosecha en el sector Bananero, se realizó en el cantón El Guabo, Ubicado en el Noroccidente de la provincia de El Oro, al sur de la costa ecuatoriana, con una extensión de 61.847,95 hectáreas. Se planteó como objetivos: realizar una investigación de mercado, para determinar las características de la demanda y oferta del producto; realizar un análisis FODA para identificar los factores internos y externos que intervienen en la comercialización del producto; y, diseñar estrategias que permitan posicionar la bomba postcosecha en el sector bananero. Para el respectivo análisis del mercado se consideró tomar como población a los productores de banano del cantón El Guabo, que se encuentran registrados en la Dirección Provincial del Ministerio de Agricultura y Ganadería de El Oro. Además, se procedió a realizar entrevistas a los diferentes representantes de instituciones públicas y privadas para recolectar información que permita un planteamiento de datos a la presente investigación. Se concluye que existe una creciente demanda por los equipos de fumigación, debido que las bombas de fumigación post-cosecha son uno de los equipos de mayor uso en las operaciones agrícolas. Gran parte de los productores estarían dispuestos a emplear la bomba de VPC, ya que la bomba de mochila es la más utilizada y no cumple las expectativas en cuanto a productividad y eficiencia. Los productores esperan que los equipos de fumigación les proporcionen beneficios, mejor cobertura, disminución de daños en los accesorios. Se realizó el análisis FODA para la comercialización del equipo de fumigación post-cosecha con VPC, en la cual se pudo identificar las fortalezas, debilidades, oportunidades y las posibles amenazas que pueda enfrentar la comercialización de la bomba de fumigación post-cosecha con VPC. La empresa dispone de una amplia cartera de clientes, es líder en el mercado de la venta de insumos, maquinarias y demás equipos agrícolas. Se cuenta con una estructura organizativa, técnica y logística, con la disponibilidad de diferentes agencias a nivel nacional. Existen ciertos factores que pueden incidir negativamente en la comercialización de la cual la empresaThe present Marketing Plan for the positioning of the post-harvest pump in the banana sector, was conducted in the canton El Guabo, located in the northwest in El Oro province, in the south of the Ecuadorian coast, with an extension of 61.847,95 hectares. The objectives proposed were: Undertake a market research, to determine the characteristics of the demand and supply of the product; carry out a SWOT analysis to identify the internal and external factors that are involved in the marketing of the product; and design strategies that allow us to position the pump post-harvest in the banana sector. For the respective market analysis it was considered to take as population the banana farmers of the canton El Guabo, who are registered at the Provincial Directorate of the Board of Agriculture and Livestock of the province El Oro. In addition, some interviews were conducted to the different delegates of public and private institutions to collect information that facilitates an approach of data to the present investigation. It is concluded that there is a growing demand of fumigation equipment, because the post-harvest fumigation pumps are one of the equipment of greater use in farming operations. A large number of the farmers would be willing to use the pump of VPC, since the backpack pump is the most used and therefore it does not meet the expectations in terms of productivity and efficiency. The farmers hope that fumigation equipment provide them with benefits, better coverage, and reduction of damages in the accessories. The SWOT analysis was conducted for the marketing of the postharvest fumigation equipment with VPC, in which it could be identified the strengths, weaknesses, opportunities and the potential threats that the marketing of the pump of post-harvest fumigation with VPC could confront. The company has a wide portfolio of clients, it is the market leader in the sale of consumables, machinery and other agricultural equipment. There is an organizational, technical and logistics structure, with the availability of different agencies at the national level. There are some factors that can adversely affect the marketing of which the company will take the respective previsions in order to minimize the possible impact that it may cause. Strategies that will positio

Erosion caused by propeller jets in a low energy harbour basin

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Journal of Hydraulic Research on January, 2017, available online at: http://www.tandfonline.com/10.1080/00221686.2016.1252801Field data of a harbour basin are compared with analytical formulations for predicting maximum scouring depth due to propeller jets. Spatial data analysis of seven-year biannual bathymetries quantifies the evolution of the scouring hole along with the sedimentation process within a harbour basin. The maximum scouring depth is found to be of the order of the propeller diameter with a maximum scouring rate within the first six months of docking manoeuvring. Three of the analysed expressions yielded realistic results while observed discrepancies between the theoretical predictions and field data are related to scaling factors. The outcomes of this analysis can be extrapolated to other harbours to improve their management. The obtained results highlight the importance of field data in developing combined physical and numerical models.Peer ReviewedPostprint (author's final draft

Retribuciones económicas y adopción de tecnología en maíz con crédito ordinario y crédito compartiendo riesgo

Problema de gran Importancia para los paises menos desarrollados es el de la agricultura de subsistencia. A esta actividad se dedica en Colombia aproximadamente unos 700 000 personas de escasos recursos económicos, comúnmente denominadas "pequeños productores", quienes se caracterizan fundamentalmente por poseer pocos recursos de tierra y capital.Maíz-Zea may

Experimental set-up and calibration errors for mapping wave-breaking pressures on marine structures

Capturing the detailed spatial variation of pressures induced by breaking waves on physical model structures has become possible using a high resolution mapping system. It can provide data with 4 measuring points/cm2, whereas the denser pressure measurements reported so far, for wave-structure interaction experiments, were limited to 0.4 pressure transducers/cm2. The paper explores the main parameters affecting the accuracy and errors of pressure data induced by laboratory set-up and system calibration. The quality of pressure maps deteriorates due to cushioning effects associated to air trapped in the sensor during manufacturing. The sensor's response is also shown to depend on the loading conditions. Non-calibrated outputs returned for impact pressures induced by impinging water-jets are more than three times smaller than the outputs recorded for static pressures, and/or for pressures developed when a material less compliant than water comes forcibly in contact with the sensor. Therefore, the calibration settings must be similar to the conditions anticipated in the experiments. To this end, a set-up and calibration methodology, designed specifically for hydraulic model tests with waves breaking on structures, are proposed and discussed in the paper.Peer ReviewedPostprint (author's final draft

Study of the bed velocity induced by twin propellers

Twin propellers without a rudder were studied using a physical model with a fixed clearance distance and three different rotating velocities. Experimental results were compared with results from theoretical expressions developed over the past 50 years for the efflux velocity, axial velocity, and maximum bed velocity. It was found that the efflux velocity equations overestimated the experimental results, whereas the computed axial velocities matched the experimental data reasonably well. However, when maximum bed velocity expressions were compared with experimental results, only one method was found to behave better; overestimation resulted if a quadratic superposition of single jets was used.Peer ReviewedPostprint (published version

Impulsive wave loads on rigid structure, an experimental approach

Within the European project ‘Hydralab IV’, HyRes we aim to improve the characterization of wave loads on rigid structures and the associated response by carrying out some laboratory experiments. Wave loads on rigid structures are divided into quasi static loads and impact loads. If the physics of quasi-static loads due to waves is well known, this cannot be said the same for wave impact loads. A comprehensive method to design maritime rigid structures under impact loads does not exist yet and the actual design method suggests avoiding scenarios where impact loads can take place. In the last decade, some laboratory experiments have been carried out; however some questions remain still unanswered. The use of different sensors can lead to significant changes in the results and an “exhaustive comparison” between dissimilar types of sensors has not been done yet. Even the magnitude of these forces can be underestimated during a laboratory test just for the choice of sample frequencies which are too low. This paper describes the experiments performed on a small scale flume at UPC on a scaled vertical breakwater in order to compare the results of pressure transducers and force load cells. Moreover, a high frequency sampler (up to 20 KHz) was used in order to understand the importance of sample frequency on the magnitude of the results. A simplified scenario has been set up in order to make the data analysis easier.Postprint (published version

El papel de la educación para la salud en la prevención del VIH/sida : una aproximación desde la educación para el desarrollo en Centroamérica

El trabajo describe una experiencia de educación para el desarrollo, en materia de salud y calidad de vida, implementada en el marco de una actuación continuada de cooperación universitaria en Centroamérica. La creación de un espacio de discusión sobre temas de desarrollo, calidad de vida y salud sirve de soporte e impulso a la aplicación de políticas locales; a la prestación de apoyo técnico en el diseño, la preparación y la ejecución de investigaciones socioeducativas; a la capacitación de personas mediadoras en salud, y al propiciamiento del intercambio de experiencias entre profesionales e instituciones. Metodológicamente, el trabajo se aborda en tres fases: análisis de la realidad mediante investigación aplicada enfocada fundamentalmente a la problemática del VIH/sida, realización de un diagnóstico participativo sobre la situación real de los grupos de riesgo para la toma de decisiones en la construcción de un discurso preventivo adaptado a la realidad contextual y, finalmente, impulso coordinado de las acciones de educación para el desarrollo que conforman la experiencia. La consolidación de esta alianza interinstitucional, que actúa sobre necesidades reales y demandadas en este contexto, está generando cambios sustanciales y tangibles en los hábitos y en la calidad de vida de la población local.El treball descriu una experiència d'educació per al desenvolupament en matèria de salut i qualitat de vida implementada en el marc d'una actuació continuada de cooperació universitària a l'Amèrica Central. La creació d'un espai de discussió sobre temes de desenvolupament, qualitat de vida i salut serveix de suport i d'impuls a l'aplicació de polítiques locals; a la prestació de suport tècnic en el disseny, la preparació i l'execució d'investigacions socioeducatives; a la capacitació de persones mediadores en salut, i al propíciament de l'intercanvi d'experiències entre professionals i institucions. Metodològicament, el treball s'aborda en tres fases: anàlisi de la realitat mitjançant investigació aplicada enfocada fonamentalment a la problemàtica del VIH/sida, realització d'un diagnòstic participatiu sobre la situació real dels grups de risc per prendre decisions sobre la construcció d'un discurs preventiu adaptat a la realitat contextual i, finalment, impuls coordinat de les accions d'educació per al desenvolupament que conformen l'experiència. La consolidació d'aquesta aliança interinstitucional, que actua sobre necessitats reals i sol·licitades en aquest context, està generant canvis substancials i tangibles en els hàbits i en la qualitat de vida de la població local.This study describes an education for development experience related to health and quality of life implemented in the framework of an on-going university cooperation action in Central America. A space for debate on these issues was created to support and promote the implementation of local policies; provide technical support for the design, preparation and implementation of socio-educational research; train health mediators; and foster the exchange of experiences among professionals and institutions. Methodologically, the work comprises three phases: an analysis of the problem of HIV/AIDS using an applied research approach, a participatory diagnosis of the actual situation of risk groups in order to make decisions to construct a health prevention discourse adapted to the contextual reality and, finally, the coordinated promotion of educational actions for development. The consolidation of this inter-institutional alliance, which acts on real needs in this context, is producing substantial, tangible changes in the habits and quality of life of the local community

El Uso de las Redes Sociales en la Educación y Promoción de la Salud. Una Experiencia de Empoderamiento Social en Nicaragua

Resumen:En este trabajo se presenta una experiencia de Educación para la Salud basada en el empoderamiento social y orientada a la mejora de las condiciones generales de salud de la población. Estuvo apoyada en redes sociales telemáticas y desarrollada, desde la Universidad, en la región de Chontales (Nicaragua). Para la investigación se han desarrollado grupos de discusión con docentes, estudiantes y líderes de opinión locales, que han colaborado activamente en diversas actividades propuestas de educación y promoción de la salud. Para el análisis de los datos se ha empleado el programa de análisis cualitativo Atlas.ti, creando previamente el sistema de categorías y posteriormente los diferentes códigos de análisis. El conjunto de conclusiones del estudio pone de manifiesto el consenso de los actores implicados sobre la utilidad y potencialidad de las redes sociales en la Educación para la Salud y el empoderamiento social, así como la necesidad y demanda explícita de una mayor formación específica y acceso a los recursos para poder conseguir un impacto social real. Abstract:This paper presents a Health Education experience based on social empowerment and aimed at improving the general health conditions of the population. It was supported in telematics social networks and developed, from the University, in the region of Chontales (Nicaragua). For the research, discussion groups have been developed with local teachers, students and opinion leaders, who have actively collaborated in various proposed education and health promotion activities. After creating the system of categories and the different codes of analysis, the qualitative analysis program Atlas.ti was used for the analysis of the data. The set of conclusions of the study shows the consensus of the actors involved on the utility and potential of social networks in Health Education and social empowerment, as well as the need and explicit demand for greater specific training and access to the required resources to achieve a real social impact

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