128 research outputs found

    Can a Soil Mineralization Test Improve Wheat and Corn Nitrogen Diagnosis?

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    A network of field studies determined that the traditional method for predicting soil N availability …a pre-plant nitrate test … can be combined with an indicator of soil N mineralization capacity to significantly improve the diagnosis for soil N availability for both wheat and corn.Fil: Reussi Calvo, Nahuel Ignacio. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Laboratiorio de Suelos. Fertilab; ArgentinaFil: Echeverría, Hector E.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Sainz Rozas, Hernan Rene. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Berardo, Angel. Laboratiorio de Suelos. Fertilab; ArgentinaFil: Diovisalvi, Natalia. Laboratiorio de Suelos. Fertilab; Argentin

    Proyecto de Recuperación Escombreras en 12 municipios de la provincia de Valladolid

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    Resumen no disponibleGrado en Ingeniería Forestal y del Medio Natura

    Noise in Electric Motors: A Comprehensive Review

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    Electric machines are important devices that convert electrical energy into mechanical energy and are extensively used in a wide range of applications. Recent years have seen an increase in applications where electric motors are used. The frequent use of electric motors in noise-sensitive environments increases the requirements placed on electric motors intended for these applications, especially when compared to electric motors commonly used in industrial applications. This paper provides a comprehensive review of electric motor noise. Firstly, a brief introduction to noise is given. Then, the sources of electromagnetic noise and vibration in electric machines, including mechanical, aerodynamic and electromagnetic factors, are presented. Different methods such as analytical, numerical and semi-analytical for calculating electromagnetic force, natural frequencies and noise are also analyzed. Various methods for noise reduction are presented, including skewing, stator and rotor notching and slot opening width. Finally, noise measurement standards and procedures are described.This work received financial support from the Basque Government through the Bikaintek program (Grant no. 016-B2/2021)

    Magnetic field-based arc stability sensor for electric arc furnaces

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    During the last decades the strategy to define the optimal Electric Arc Furnaces (EAF) electrical operational parameters has been constantly evolving. Foaming slag practice is currently used to allow high power factors that ensures higher energy efficiency. However, this performance depends on strict electric arc stability control. Control strategies for these are normally defined for alternating current furnaces (AC EAF) and are based on intrusive and highly expensive systems. In this work we analyze the variation of the magnetic field vector around the direct current EAF (DC EAF) and its relationship with arc stability. We propose a cheap stability control system with no installation or integration requirements and thus, easily implementable to both AC and DC EAFs. To this end we have built a non-intrusive and low-cost 3-axis Hall-effect sensor that can be mounted neighboring the furnace’s electrical bars. The sensor allows acquiring the magnetic field magnitude and orientation that provides a newly defined arc stability factor metric. This proposed Arc Stability Index has been compared with three different alternative well established and more expensive measurement methodologies obtaining with similar results. The proposed index serves as a closed loop signal to the electrical regulation for controlling the arc voltage, ensuring the most convenient arc length that guaranties non-instabilities. The new system was developed and industrially validated at two different DC EAF’s in ArcelorMittal demonstrating an improvement of 6.7 kWh per Liquid steel ton during the evaluated period and a time reduction of 1.1 min per heat over the current standard procedure. Additional validation tests were also carried out also in ArcelorMittal AC EAF proving the capability of this technology for both AC and DC of furnaces.Partial financial support of this work by the Basque Govern-ment (Hazitek AURRERAB ZE-2017/00009 and FASIN ZE-2016/0016 Projects) is gratefully acknowledged

    Sag-tension evaluation of high-temperature gap-type conductor in operation

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    [EN] Low-sag conductors are characterised by their ability to operate above the "knee-point temperature" (KPT). Sag-tension performance must be calculated while designing a new overhead line. The ampacity limit of the conductor is influenced by the sag and the temperature of the conductor. The maximum sag must be limited to a certain value to ensure a safe clearance between the conductor and ground. In this study, a gap-type conductor in operation was monitored to evaluate the actual KPT. The KPT in low-sag conductors is a crucial factor since it affects the sag of the conductor, which must be limited for safety reasons. The KPT was detected based on the change in the coefficient of thermal expansion value of the conductor. To perform this detection, the conductor tension and temperature were monitored. This study proposes a procedure to estimate the coefficient of thermal expansion (CTE) value. The results showed a gradual displacement in CTE. This procedure was used to perform measurements in a pilot line.This work is financially supported by the Ministerio deEconomía, Industria y Competitividad, under the project DPI2016-77215-R (AEI/FEDER, UE) and by the Universityof the Basque Country UPV/EHU (ELEKTRIKER researchgroup GIU20/034)

    Uncertainties in the Testing of the Coefficient of Thermal Expansion of Overhead Conductors

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    Overhead lines can be replaced by high temperature low sag (HTLS) conductors in order to increase their capacity. The coe cients of thermal expansion (CTE) of the HTLS conductors are lower than the CTE of conventional conductors. The utilities and conductor manufacturers usually carry out the verification of the CTE of the overhead conductors in an actual size span. The verification is based on the observation of the change of the conductor length as a result of the conductor temperature change. This process is influenced by the coe cient of thermal expansion to be verified. However, there are other factors that also a ect it. This paper analyzes the e ect of some of the uncertainty sources in the testing of the coe cient of thermal expansion of the overhead conductors. Firstly, the thermal expansion process is described and the uncertainty sources related to the conductor and the line section are identified. Then, the uncertainty sources and their e ect on the CTE testing are quantified.This research was funded by the MINISTERIO DE ECONOMÍA, INDUSTRIA Y COMPETITIVIDAD, Spain, DPI2016-77215-R (AEI/FEDER, UE)

    RIESGO DE SUBSIDENCIA POR DISOLUCIÓN DE EVAPORITAS EN LA CIUDAD DE CALATAYUD (ESPAÑA)

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    Se realiza una cartografía de sentidos de hundimiento determinados a partir de grietas y otras deformaciones, reportadas fundamentalmente por alumnos del IES Emilio Jimeno de Calatayud. La cartografía permite identificar zonas de hundimiento preferente en la ciudad, pero las limitaciones del muestreo, escaso y con distribución heterogénea, limita la validez de los resultados encontrados.Los datos de aforo y de calidad de las aguas de la Cuenca de Calatayud y su entorno, permiten determinar la existencia de procesos de disolución de evaporitas que alcanzan las 125.000 toneladas anuales.Estos procesos de disolución son responsables, en gran medida, de los problemas geotécnicos que aquejan la ciudad de Calatayud y otros núcleos de su entorno.El análisis de los datos permite definir un modelo en el que las entradas de aguas subterráneas son del orden de 175 Hm3/año, procediendo del propio río Jalón, aguas arriba de la Cuenca de Calatayud, del río Jiloca, con infiltraciones sistemáticas a lo largo de su cauce y, posiblemente, por puntos no determinados del borde sur de la Cuenca de Calatayud.Aguas abajo, en el límite norte de la cuenca, la presencia de materiales impermeables fuerza la salida de los flujos subterráneos al tiempo que marca un nivel de base para el nivel piezométrico. Considerando este nivel de base y la hidrodinámica de las aguas freáticas, el nivel de saturación, bajo la ciudad de Calatayud, se encuentra a escasos metros.<br /

    Photovoltaic Local Energy Communities—Design of New Energy Exchange Modalities—Case Study: Tolosa

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    Energy communities (ECs) can become a potential alternative to promote the fight against climate change. Technological progress and price reductions in recent years have made renewable energy-generation systems increasingly affordable and have generated economic benefits by reducing the value of electricity bills for community members, as well as reducing the growing environmental impact. In this context, the authors have taken Tolosa as a case study and conducted a technical and economic analysis of different possible structures of ECs (physical, virtual, with or without storage, participants with different types of consumption, etc.) by comparing them with each other. The generation capacity of the community and the optimal energy-management algorithms have been illustrated, from which the economic benefits for each member are extracted. A dynamic distribution factor is established as the basis of the algorithms, making the benefits fairer. The results obtained from this work, in addition to illustrating the economic benefits that each type of participant can receive, help to define the most appropriate community structure for each participant while highlighting the social and climate benefits that ECs can provide.This work is financially supported by the Basque Government under Grant IT1647-22 (ELEKTRIKER research group), and by the Ministerio de Ciencia e Innovación, the Agencia Estatal de Investigación. and the European Union under Grant TED2021-129930A-I00 funded by MCIN/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”

    A New Methodology to Manage FPGA Distributed Memory Content via Bitstream for Xilinx ZYNQ Devices

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    This paper proposes a methodology to access data and manage the content of distributed memories in FPGA designs through the configuration bitstream. Thanks to the methods proposed, it is possible to read and write the data content of registers without using the in/out ports of registers in a straightforward fashion. Hence, it offers the possibility of performing several operations, such as, to load, copy or compare the information stored in registers without the necessity of physical interconnections. This work includes two flows that simplify the designing process when using the proposed approach: while the first enables the protection or unprotection of writing on different partial regions through the bitstream, the second permits homogeneous instances of a design implemented in different reconfigurable regions to be obtained without losing efficiency. The approach is based and has been physically validated on the ZYNQ from Xilinx, and when using partially reconfigurable designs, it does not affect the hardware overhead nor the maximum operating frequency of the design.This work has been supported, within the fund for research groups of the Basque university system IT1440-22, by the Department of Education and, within PILAR ZE-2020/00022 and COMMUTE ZE-2021/00931 projects, by the Hazitek program, both of the Basque Government; the latter also by the Ministerio de Ciencia Innovación of Spain through the Centro para el Desarrollo Tecnológico Industrial (CDTI) within the projects IDI-20201264 and IDI-20220543, and through the Fondo Europeo de Desarrollo Regional 2014–2020 (FEDER funds)
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