The present work is aimed to simulate the Friction Stir Welding process as a three-dimensional thermally coupled viscoplastic flow. A Finite Element technique is employed, within the context of a general purpose FEM framework, to provide the temperature distributions and the patterns of plastic flow for the material involved in the welded joints. The computational tool presented here may be of great relevance for technologist seeking to set the process control variables, as they are intended to obtain suitable material properties that yield the adequate on service response of the structural components
This paper proposes a PD-like controller applied to the delayed bilateral teleoperation of wheeled robots with force feedback in face of asymmetric and varyingtime delays. In contrast to bilateral teleoperation of manipulator robots, in these systems there is a mismatch between the models of the master and slave (mobile robot), problem that is approached in this work, where the system stability is analyzed. From this study, it is possible to infer the control parameters, depending on the time delay, necessary to assure stability. Finally, the performance of the delayed teleoperation system is evaluated through tests where a human operator drives a 3D simulator as well as a mobile robot for pushing objects.
This paper proposes a control scheme for a stable teleoperation of non‐holonomic mobile manipulator robots. This configuration presents high‐coupled dynamics and motion redundancy. The problem approached in this work is the teleoperation of the end effector velocity of the Mobile Manipulator, while system redundancy is used to achieve secondary control objectives. We considered variable asymmetric time delays as well as non‐passive models of operator and environment. From this study, it is possible to infer the control parameters, depending on the time delay, in order to assure stability. Finally, the performance of the delayed teleoperation system is evaluated through simulations of human‐in‐the‐loop internet teleoperation.
The influence of BaTiO 3 content on the composite dielectric properties was investigated by finite element method (FEM). This method is attractive because of its technological applications such as those in electromagnetic shields, since it allows to determine the dielectric constant of heterogeneous mediums and show or display the electric field into the material in order to understand the interfacial behaviours. The dielectric response of an anisotropic and periodic heterostructure, was evaluated and quantified by means of a quasistatic approximation using Laplace's equation which was solved by 3D FEM.The numerical calculations were confronted with experimental data. Measurements of the effective permittivity were carried out in samples prepared by dipping technique.
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