Slag entrainment during steel teeming-drain operations from a steel ladle impacts negatively steel cleanliness and quality. In the present work water modeling and mathematical simulations using a multiphase model for momentum and heat transfer were employed to understand the mechanisms of vortex funnel drain and sink drain flows. The critical bath height for vortex development increases with steel throughput and valve gate opening. Six stages during vortex development are identified, passing from a dimple formation on the bath surface until sink drain which begins when the bath level has the same magnitude as the nozzle diameter. This later drain pattern is independent from any other teeming-draining variable being only a function of the bath height and nozzle diameter; when they are about the same the metal-interface collapses. The temperature gradients originated by the heat losses of the ladle to the surroundings provide buoyancy forces that are large enough to influence liquid motion in the ladle. At large bath levels steel observes long-vertical recirculating flows and at low bath levels these flows change to horizontalcircular recirculating flows that become a seed for later vortex development. These buoyancy forces increase the critical height for vortex development and slag entrainment.
The present work analyzes the influence of crown shape on the distribution of stresses and deformation for rolling processes. This study consists of a Finite Element Analysis considering combinations of crown shape for Back Up Roll and Work Roll, rolling forces, properties of materials and dimensions of rolls and strip. An analysis of the rolls based on a double cantilever model with the fulcrum of the beams in a centerline mill was carried out. The results show that maximum stress concentrations for all combinations of crown shape analyzed appear on both sides 787.4 mm from the mill centerline, exactly on the sides of the strip. In this area, the maximum stress for the best combination of crown shape is larger than in the centerline mill, increasing from 34.2 MPa to 163.0 MPa. This is proportional according to Hooke’s law for which strain of rolls increases from 3.4067 × 10−4 to 4.8368 × 10−4. The worst combinations of crown shapes were obtained when the shapes of the barrel are the same for the BUR and WR; for example: Combination 1 (BUR Positive–WR Positive), Combination 5 (BUR Flat–WR Flat), and Combination 9 (BUR Negative–WR Negative).
En el presente trabajo se desarrolló una interfaz mioeléctrica para controlar un prototipo de prótesis de mano impresa con tecnología 3D. Se logró adquirir y acondicionar señales electromiográficas a través de electrodos de superficie. Dicha interfaz contiene etapas de adquisición, amplificación, filtrado, rectificación y suavizado. Lo que permite obtener amplitudes de señales electromiográficas (EMG) adecuadas para su digitalización dentro de un algoritmo implementado con un microcontrolador Arduino UNO. Para las pruebas de funcionamiento se imprimió en 3D un diseño de mano mecánica (raptor hand, 2017).
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