FRVT - Capítulos de Libros Internacionales

Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/942

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    Efecto sobre la tensión de rotura en flexión de la altura de la sección en elementos estructurales de pino ponderosa.
    (UTN FRVT., 2023) Guillaumet, Alfredo; Manavella, Roberto; Filippetti, María Cecilia; Meyer, Lía Caren; Tosco, Andrea
    La influencia de las dimensiones de la sección transversal en la resistencia a la flexión es un efecto contemplado en distintos reglamentos de estructuras de madera. En las normativas europeas y de Argentina la expresión de ajuste es común para todas las especies y procedencias, mientras que en la de Estados Unidos de Norteamérica y Chile se considera el grado estructural o la especie. Se han realizado numerosos estudios para verificar la precisión de las expresiones de ajuste para cada combinación de especie -procedencia. En este trabajo se analiza el efecto de la altura de la sección transversal, sobre la resistencia en flexión, en piezas de tamaño estructural de pino ponderosa cultivado en la región andino-patagónica norte de Argentina. Los ensayos de flexión se realizaron sobre 440 cuerpos de prueba de tamaño estructural según las normas argentinas. Los resultados indicaron una tendencia decreciente de la tensión de rotura en flexión con el aumento de la altura, el efecto de la altura resultó superior en la madera de inferior calidad. Los resultados obtenidos convalidan, para elementos estructurales de pino ponderosa, la aplicación del criterio de ajuste propuesto en la norma IRAM 9664 (2013) y el reglamento INTI-CIRSOC 601 (2016).
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    Numerical Modelling of a Cutting Arc Torch
    (Jan Awrejcewicz. INTECH, 2014-02-14) Mancinelli, Beatriz; Minotti, Fernando Oscar; Prevosto, Leandro; Kelly, Héctor
    Plasma cutting is a process of metal cutting at atmospheric pressure by an arc plasma jet, where a transferred arc is generated between a cathode and a work-piece (the metal to be cut) acting as the anode . Small nozzle bore, extremely high enthalpy and operation at relatively low arc current (≈ 10 ÷ 200) A are a few of the primary features of these torches. The physics involved in such arcs is very complicated. The conversion of electric energy into heat within small volumes causes high temperatures and steep gradients. Dissociation, ionization, large heat transfer rates (including losses by radiation), fluid turbulence and electromagnetic phenomena are involved. In addition, wide variations of physical properties, such as density, thermal conductivity, electric conductivity and viscosity have to be taken into account.
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    On the Double-Arcing Phenomenon in a Cutting Arc Torch.
    (2011) Prevosto, Leandro; Kelly, Héctor; Mancinelli, Beatriz
    Transferred arc plasma torches are widely used in industrial cutting process of metallic materials because of their ability to cut almost any metal and the very high productivity that can be achieved with this technology (Boulos et al., 1994). The plasma cutting process is characterized by a transferred electric arc that is established between a cathode, which is a part of the cutting torch, and a work-piece (the metal to be cut) acting as the anode. In order to obtain a high-quality cut, the plasma jet must be as collimated as possible and also must have a high power density. To this end, the transferred arc is constricted by a metallic tube (a nozzle) with a small inner diameter (of the order of one millimeter). Usually, a vortex-type flow with large axial and azimuthal velocity components is forced through the nozzle to provide arc stability and to protect its inner wall. In such case the hot arc is confined to the center of the nozzle, while centrifugal forces drive the colder fluid towards the nozzle walls, which are thus thermally protected. The axial component of the gas flow continuously supplies cold fluid, providing an intense convective cooling at the arc fringes. In addition, the vortex flow enhances the power dissipation per unit length of the arc column, resulting in high temperatures at the arc axis. Since the nozzle is subjected to a very high heat flux, it is made of a metal with a high thermal conductivity (copper is broadly used). The arc current is of the order of ten up to a few hundred amperes, and the gas pressure is several atmospheres. Arc axis temperatures around 15 kK are usual, but larger values, close to 25 kK or even higher, have been reached.
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    The Impact of the Use of Large Non-Linear Lighting Loads in Low-Voltage Networks.
    (IntechOpen., 2018) Milardovich, Natalio; Prevosto, Leandro; Lara, Miguel; Milardovich, Diego
    The principal numerical and experimental results obtained by the authors on the har monic power losses in low-voltage networks in the lighting area have been summarized in this review. Light-emitting diodes (LEDs) and compact fluorescent lamp (CFL) loads were considered. Four-core cables and four single-core cable arrangements were exam ined. The cables were modeled by using electromagnetic finite element analysis software. It was found that the cross section of the neutral conductor plays an important role in the derating of the cable ampacity due to the presence of a high level of triplen harmonics in the distorted current. In order to reduce the third-order harmonic currents in the neutral conductor, an experimental investigation of diversity factors for LED in combination with CFL and LED lamps was also performed. Attention was paid to the reduction of the third order harmonic current, which is mainly responsible for the strong increase in power losses in the neutral conductor of low-voltage installations. The convenience of having LED lamps designed to operate as two-phase loads is suggested for certain applications.