1,894 research outputs found

    Application of Semi-Empirical Ventilation Models in A Mediterranean Greenhouse with Opposing Thermal and Wind Effects. Use of Non-Constant Cd (Pressure Drop Coefficient Through the Vents) and Cw (Wind Effect Coefficient)

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    The present work analyses the natural ventilation of a multi-span greenhouse with one roof vent and two side vents by means of sonic anemometry. Opening the roof vent to windward, one side vent to leeward, and the other side vents to windward (this last vent obstructed by another greenhouse), causes opposing thermal GT (m3 s−1) and wind effects Gw (m3 s−1), as outside air entering the greenhouse through the roof vent circulates downward, contrary to natural convection due to the thermal effect. In our case, the ventilation rate RM (h−1) in a naturally ventilated greenhouse fits a second order polynomial with wind velocity uo (RM = 0.37 uo2 + 0.03 uo + 0.75; R2 = 0.99). The opposing wind and thermal effects mean that ventilation models based on Bernoulli’s equation must be modified in order to add or subtract their effects accordingly—Model 1, in which the flow is driven by the sum of two independent pressure fields GM1=√(∣∣G2T±G2w∣∣) , or Model 2, in which the flow is driven by the sum of two independent fluxes GM2=|GT±Gw| . A linear relationship has been obtained, which allows us to estimate the discharge coefficient of the side vents (CdVS) and roof vent (CdWR) as a function of uo [CdVS = 0.028 uo + 0.028 (R2 = 0.92); CdWR = 0.036 uo + 0.040 (R2 = 0.96)]. The wind effect coefficient Cw was determined by applying models M1 and M2 proved not to remain constant for the different experiments, but varied according to the ratio uo/∆Tio0.5 or δ [CwM1 = exp(−2.693 + 1.160/δ) (R2 = 0.94); CwM2 = exp(−2.128 + 1.264/δ) (R2 = 0.98)]

    Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

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    The present work has developed a methodology based on thermography and sonic anemometry for studying the microclimate in Mediterranean greenhouses equipped with air heaters and polyethylene distribution ducts to distribute the warm air. Sonic anemometry allows us to identify the airflow pattern generated by the heaters and to analyze the temperature distribution inside the greenhouse, while thermography provides accurate crop temperature data. Air distribution by means of perforated polyethylene ducts at ground level, widely used in Mediterranean-type greenhouses, can generate heterogeneous temperature distributions inside the greenhouse when the system is not correctly designed. The system analyzed in this work used a polyethylene duct with a row of hot air outlet holes (all of equal diameter) that expel warm air toward the ground to avoid plant damage. We have observed that this design (the most widely used in Almería’s greenhouses) produces stagnation of hot air in the highest part of the structure, reducing the heating of the crop zone. Using 88 kW heating power (146.7 W∙m−2) the temperature inside the greenhouse is maintained 7.2 to 11.2 °C above the outside temperature. The crop temperature (17.6 to 19.9 °C) was maintained above the minimum recommended value of 10 °C

    The palm tree in the landscape of the Bajo Segura basin irrigated area. An identity element in need of protection

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    La palmera, como aprovechamiento agrícola, ha estado estrechamente vinculada al espacio de la Huerta generado a lo largo de los siglos en la llanura aluvial del Segura. Los múltiples usos derivados de ésta han fortalecido su permanencia, a la vez que la imagen identitaria con que se asocia al territorio. Su presencia ha quedado plasmada en escritos de todo tipo desde la Ilustración hasta nuestros días, lo que permite contrastar la visión de entonces con la situación que atraviesa en la actualidad. Para ello se analizan tres ámbitos diferentes, San Isidro, una población entre palmeras tras la colonización de suelos salinos; el Palmeral de Orihuela, como pervivencia de un enclave histórico ligado a los rendimientos mixtos de la tierra; y finalmente, la dispersión generalizada de la palmera por el medio agrario.The palm tree, regarded as an agrarian resource, has been closely linked to the orchards, or spaces of "Huerta", developed over centuries in the Segura River fertile plains. The multiple uses of the palm tree have guaranteed its continuity and strengthened its association with the identity image related to this territory. Its presence has been captured in all types of written documents, from the Enlightenment to recent times, allowing us to compare ancient vision and present situation. To develop this comparison the paper analyses three different contexts: San Isidro, a town built between palms previously planted on saline soil, the Palmeral of Orihuela, a survival remain of a historic site associated with mixed cultivation of land and, finally, the generalized palm tree dispersion through the agrarian landscape

    The palm tree, an identity-defining element in the Huerta landscape of Bajo Segura (SE of Spain)

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    La palmera, por sus múltiples aprovechamientos (agrícola, constructivo, ritual e industrial), ha sido tradicionalmente un elemento identitario en el paisaje huertano del Bajo Segura. En las últimas décadas su presencia se ha restringido, al perder las funciones que antaño cumplía, a lo que se ha unido la plaga del picudo rojo y la comercialización masiva con fines ornamentales para las nuevas áreas residenciales. El artículo aborda la presencia de esta especie en el territorio desde diversas visiones y en diferentes épocas: la estética de la literatura de viajes, la productiva de los tratados científicos o la emocional de las obras de creación.The palm tree, because of its numerous uses (agricultural, constructive, ritual and industrial), has been traditionally an identity-defining element in the landscape of the Bajo Segura irrigated area (SE of Spain). In recent decades, its presence has been limited, by the loss of functions that palm tree previously carried out, currently joined to the red palm weevil pest (Rhynchophorus ferrugineus) and the massive sale with ornamental purposes in the new built-up areas emerged from residential tourism boom. This article deals with the presence of the Palm in the territory from several views and in different times: the aesthetic of travel literature, the productive of scientific reports or the emotional of artistic works

    Nonlinear Observability Algorithms with Known and Unknown Inputs: Analysis and Implementation

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    The observability of a dynamical system is affected by the presence of external inputs, either known (such as control actions) or unknown (disturbances). Inputs of unknown magnitude are especially detrimental for observability, and they also complicate its analysis. Hence, the availability of computational tools capable of analysing the observability of nonlinear systems with unknown inputs has been limited until lately. Two symbolic algorithms based on differential geometry, ORC-DF and FISPO, have been recently proposed for this task, but their critical analysis and comparison is still lacking. Here we perform an analytical comparison of both algorithms and evaluate their performance on a set of problems, while discussing their strengths and limitations. Additionally, we use these analyses to provide insights about certain aspects of the relationship between inputs and observability. We found that, while ORC-DF and FISPO follow a similar approach, they differ in key aspects that can have a substantial influence on their applicability and computational cost. The FISPO algorithm is more generally applicable, since it can analyse any nonlinear ODE model. The ORC-DF algorithm analyses models that are affine in the inputs, and if those models have known inputs it is sometimes more efficient. Thus, the optimal choice of a method depends on the characteristics of the problem under consideration. To facilitate the use of both algorithms, we implemented the ORC-DF condition in a new version of STRIKE-GOLDD, a MATLAB toolbox for structural identifiability and observability analysis. Since this software tool already had an implementation of the FISPO algorithm, the new release allows modellers and model users the convenience of choosing between different algorithms in a single tool, without changing the coding of their modelThis research was supported by the Spanish Ministry of Science, Innovation and Universities through the project SYNBIOCONTROL (reference DPI2017-82896-C2-2-R). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI) and by the Xunta de Galicia through grant ref. IN607B 2020-03S

    El desarrollo turístico de Orihuela y su incidencia en el poblamiento (1910-2010)

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    The century 1910-2010 represents to Orihuela municipality (SE of Spain) a momentous change that is reflected both in social aspects as in economic. Agriculture, the most determinant factor on wealth, has been pushed into the background in favour of the secondary and tertiary sectors. In this process, tourism has generated an alteration in the traditional distribution of population, which has caused the current antagonism that exists between interior lands and the coast. A group of foreign residents has been encouraged by this urban duality reaching 42,2% of total municipality population.La centuria de 1910 a 2010 representa para el municipio de Orihuela un cambio trascendental que se refleja tanto en los aspectos sociales como económicos. La agricultura, factor condicionante de la riqueza, ha quedado relegada frente a los sectores secundario y terciario. En este proceso, el turismo ha generado una alteración en la tradicional distribución del poblamiento que origina el antagonismo actual entre el interior y la costa. Esta dualidad urbana está motivada por la presencia de un colectivo de residentes extranjeros que alcanza el 42,2% de la población municipal

    Medio de carga para máquinas de musculación

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    ES2617959 A1 (20.06.2017) ES2617959 B2 (03.11.2017) P201700130 (30.01.2017)Medio de carga del tipo de los utilizados en máquinas de musculación. El medio de carga incorpora dos guías curvas (1a, 1b) colocadas de forma simétrica y cuyas caras exteriores definen sendas pistas de rodadura (11a, 11b) sobre las que pueden desplazarse sendos rodillos (3a, 3b). Los ejes (4a, 4b) de dichos rodillos (3a, 3b) están unidos entre sí mediante un resorte de extensión (5). Dos tirantes (6a, 6b) unen los ejes (4a, 4b) de sendos rodillos (3a, 3b) con un cable de carga (8). La geometría de la curva definida por las pistas de rodadura (11a, 11b) es tal que la fuerza exterior aplicada sobre el cable de carga (8) es la misma independientemente de la posición en la que se encuentren los rodillos (3a, 3b).UNIVERSIDAD DE ALMERÍ

    Creación de la identidad visual, publicidad y promoción para un proyecto musical

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    [ES] El objeto de estudio de esta tesis de fin de máster es crear una identidad original para el primer proyecto musical de un artista ficticio, con el objetivo de conseguir un proyecto dinámico, singular, llamativo y con éxito. Para ello, se procede al análisis del perfil del cantante y la fundación de su identidad artística, a la creación de una línea estética y al diseño gráfico del álbum por completo, publicidades y merchandising. La metodología usada es plurisdisciplinar y aplica un numero variado de herramientas para el análisis del artista y la creación de los productos, con el objetivo de obtener el mejor resultado posible.[EN] The object of study of this thesis is to create an original identitication for the first musical project of a fictional artist, with the aim of achieving a dynamic, singular, striking and successful project. To do this, we proceed to the analysis of the profile of the singer and the foundation of his artistic identity, the creation of an aesthetic line and the graphic design of the entire album, advertising and merchandising. The methodology used is multidisciplinary and applies a variety of tools for the analysis of the artist and the creation of products, in order to obtain the best possible result.López Martínez, A. (2020). Creación de la identidad visual, publicidad y promoción para un proyecto musical. Universitat Politècnica de València. http://hdl.handle.net/10251/152776TFG
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