En Memoria Arturo Velasco Negueruela

Sin resume

Repetitive Movements in Melon Cultivation Workers under Greenhouses

Musculoskeletal disorders cause serious problems that affect workers in many sectors. The objective of this study is the ergonomic analysis of melon cultivation farmers in Almeria-type greenhouses. For this, the rapid upper limb assessment (RULA) method has been applied after carrying out a detailed process of observing the farmers’ tasks. The study shows that 65% of the postures have a very-high-risk level, 26% high, 9% average, and no posture is found with a low risk. They also show that in 69.57% of the postures, the upper limbs are less affected than the others such as the neck, trunk, and lower limbs. Measures are proposed to improve the working conditions for workers

Labor demand and information technologies: evidence for Spain, 1980-2005

Utilizando la base de datos EU KLEMS, se contrasta la hipótesis de complementariedad entre habilidad y capital en los distintos sectores productivos en España en el periodo 1980-2005. Se analizan tres tipos de trabajadores clasificados según su nivel de habilidad sea alto, medio o bajo. Los activos de capital se van a clasificar entre activos TIC (tecnologías de la información y la comunicación) y activos no-TIC. La adquisición y el uso de activos TIC son costosos pero ha ido disminuyendo en el periodo en consideración en términos relativos a otros activos y al factor trabajo. El principal resultado que se obtiene es que existe un grado de sustituibilidad entre los trabajadores y los activos TIC a medida que la habilidad del trabajador va aumentando. De hecho, los activos TIC son muy complementarios con los trabajadores de alta habilidad. A lo largo del periodo analizado, la fracción de trabajadores con habilidad media y alta ha crecido un 21% y un 12%, respectivamente, en detrimento de los trabajadores de baja habilidad. Después de descomponer estos cambios, se descubre que existe un ajuste dentro de los sectores más que un ajuste del trabajo entre sectores.capital-skill complementarity, ICT, translog cost function, elasticity of substitution.

Portable low profile antenna at X-band

An antenna which has been conceived as a portable system for satellite communications based on the recommendations ITU-R S.580-6 and ITU-R S.465-5 for small antennas, i.e., with a diameter lower than 50 wavelengths, is introduced. It is a planar and a compact structure with a size of 40×40×2 cm. The antenna is formed by an array of 256 printed elements covering a large bandwidth (14.7%) at X-Band with a VSWR of 1.4:1. The specification includes transmission (Tx) and reception (Rx) bands simultaneously. The printed antenna has a radiation pattern with a 3dB beamwidth of 5°, over a 31dBi gain, and a dual and an interchangeable circular polarization

Diagnóstico Técnico y Análisis de Costos para la Rehabilitación de la Red Ferroviaria en la Sección Cartago-Páez-Yas

Proyecto de Graduación (Licenciatura en Ingeniería en Construcción) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería en Construcción, 2012.El proyecto titulado “Diagnóstico Técnico y Análisis de Costos para la Rehabilitación de la red ferroviaria en la sección Cartago-Páez-Yas”, pretende formar parte de la iniciativa de rescate de la red ferroviaria nacional. Tiene como objetivo realizar el diagnóstico técnico del estado actual y análisis presupuestario para una posible rehabilitación de la sección Cartago-El Yas. Para ello, se analizaron los componentes relacionados con la vía férrea, a saber, secciones transversales y sus elementos, requerimientos de diseño, métodos y materiales constructivos, amenazas naturales, metodologías de mantenimiento y aspectos legales que en conjunto determinan el espacio físico de una vía férrea. Se procedió a investigar rehabilitaciones anteriores y los trabajos actuales en la ruta Curridabat-Cartago, con el fin de detectar las actividades que se realizan, su rendimiento y su costo, y así proponer una solución integral realista al presupuesto nacional destinado para este tema. El tramo en estudio tiene una extensión de 14.4 km, desde la estación de Cartago (1466 msnm) hasta el apartadero de El Yas (1222 msnm); para mayor claridad de análisis, se dividió en cinco secciones claramente definidas. Se determinó que el 19% del recorrido presenta condiciones aceptables para pre-rehabilitación; con fines de transporte público, el 100% del tramo no es apto para su uso y requiere de intervención. Con respecto a la superestructura, el 4% de los rieles, el 100% de los durmientes y sujeciones, el 12% de las eclisas y el 100% del balastro, debe ser reemplazado. El costo para la rehabilitación es de ¢2.418.132.651,26 millones de colones, dando un costo de ¢168.714.053.03 1millones por kilómetro. Adicionalmente se incluyeron propuestas de monitoreo y de electrificación y sus respectivos presupuestos.Instituto Tecnológico de Costa Rica. Escuela de Ingeniería en Construcción

Modelling and Terrestrial Laser Scanning Methodology (2009–2018) on Debris Cones in Temperate High Mountains

Producción CientíficaDebris cones are a very common landform in temperate high mountains. They are the most representative examples of the periglacial and nival processes. This work studies the dynamic behavior of two debris cones (Cone A and Cone B) in the Picos de Europa, in the north of the Iberian Peninsula. Their evolution was measured uninterruptedly throughout each August for 10 years (2009–2018) using the Terrestrial Laser Scanning (TLS) technique. The observations and calculations of the two debris cones were treated independently, but both showed the same behavior. Therefore, if these results are extrapolated to other debris cones in similar environments (temperate high mountain), they should show behavior similar to that of the two debris cones analyzed. Material falls onto the cones from the walls, and transfer of sediments follows linear trajectories according to the maximum slope. In order to understand the linear evolution of the two debris cones, profiles were created along the maximum slope lines of the Digital Elevation Model (DEM) of 2009, and these profile lines were extrapolated to the remaining years of measurement. In order to determine volumetric surface behavior in the DEMs, each year for the period 2009–2018 was compared. In addition, the statistical predictive value for position (Z) in year 2018 was calculated for the same planimetric position (X,Y) throughout the profiles of maximum slopes. To do so, the real field data from 2009–2017 were interpolated and used to form a sample of curves. These curves are interpreted as the realization of a functional random variable that can be predicted using statistical techniques. The predictive curve obtained was compared with the 2018 field data. The results of both coordinates (Z), the real field data, and the statistical data are coherent within the margin of error of the data collection.Fondo Europeo de Desarrollo Regional - Agencia Estatal de Investigación (grant TIN2016-76843-C4-2-R)Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (grant CGL2015-68144-R

Assessment of Postural Load during Melon Cultivation in Mediterranean Greenhouses

Health and safety at work directly influence the development of sustainable agriculture. In the agricultural sector, many farm workers suffer musculoskeletal disorders caused by forced posture. The objective of this research is to assess working postures during melon cultivation in Almería-type greenhouses. The Ovako Working Posture Assessment System (OWAS) has been used with pictures of the tasks. The variables studied by multiple correspondence analysis were as follows: Subtask, Posture code, Back, Arms, Legs, Load, Risk, and Risk combination. The OWAS analysis showed that 47.57% of the postures were assessed as risk category 2, 14.32% as risk category 3, 0.47% as risk category 4, and the rest as risk category 1. Corrective measures should be implemented immediately, as soon as possible, or in the near future, depending on the risks detected

The profitability of value-added products in dairy farm diversification initiatives

A more open and competitive dairy market has encouraged certain dairy farms to adopt value-adding strategies in order to achieve a higher profitability, which may be important for farms’ survival. This paper investigated the role of some product characteristics in the profitability of value-added products in these farms. For this purpose, we used a unique database of 265 different products commercialized by 49 Spanish dairy farms that offers information on nine attributes of each product. Using hedonic models as a baseline, we examined the influence of these attributes on the margin per liter (ML) of the products. The results of the regression indicated that cheese and yogurt generated 0.688 and 1.518 € more of margin per liter than liquid milk. Similarly, we found a set of attributes that have a positive influence on ML, including possession of a certificate of protected designation of origin (PDO), the milk-type composition (proportion of sheep milk), a longer expiration period, and involvement in direct marketing strategies (DMS). However, other recognized attributes such as organic labeling, maturation period, size of the sales unit and returnable packaging did not have a significant influence on ML. Our findings also showed that firms producing more elaborated products as cheese and yogurt need a lower percentage of their production to cover the fixed costs associated to transformation and commercialization. Overall, our results revealed that the elaboration of value-added dairy products improves the profitability of dairy farms

Ultra-Broadband Directional Couplers Using Microstrip with Dielectric Overlay in Millimeter-Wave Band

Nowadays, millimeter-wave systems are being a key factor to develop wide band applications. In this paper, a directional coupler in millimeter-wave band using dielectric overlay is presented. This leads us to technology aspects, in directional coupler design, are key points to achieve the proper response of the circuit. The coupler proposed in this paper covers the 15-45 GHz band and its response has 15-dB coupling-level, 1-dB coupling-ripple and a reflection coefficient better than 10 dB

Study, design, planning process and manufacturing of a polyvalent bowsprit

The main objective of this TFG is to make a product for the naval field from the selection of an item available on the market (bowsprit for downwind sails) to make it an improvement or a modification to offer the cheaper product and accessible for all boaters. At present, this element is expensive due to use for a few years ago. According to navigation criteria and types of boats in the market, has opted for the realization of a polyvalent bowsprit because can be installed in most sailboats. It will perform a study market of such booms to acquire information and to see if we can offer this product range to other sizes of sailboats, for smaller boats, in addition to a simple and cheap product to bring production the first units to be manufactured. A prototype will be made in the workshop