Modeling of Electric Arc Furnaces ( EAF ) with electromagnetic stirring
Electromagnetic stirring can play an important role in modern Electric Arc Furnaces (EAF), as they often operate far from equilibrium conditions, with tap-to-tap times of 45 minutes or less, high electric power input and significant energy additions from fuel and oxygen. Numerical modeling is used extensively in ABB’s current efforts to optimize the EAF process with electromagnetic stirring. The modeling approach uses a Finite-Element method (FEM) for computing the forces generated by the electromagnetic stirrer, whereas the resulting flow properties, heat and mass transfer in the system is computed using a Finite-Volume (FVM) flow solver. The paper presents the numerical model in greater detail and discusses some important results. We show that electromagnetic stirring gives a more than ten-fold increase of flow velocities and circulation, compared with a flow driven by natural convection alone. The global circulation created by electromagnetic stirring dramatically reduces temperature differences in the melt, thus reducing super-heating of the melt surface and risks for cold regions. Efficient mixing of chemical species, together with even temperatures, is beneficial for efficiency and controllability of the chemical reactions in the slag-metal interface.
LES-STUDY OF MELT FLOW DRIVEN BY COMBINED INDUCTIVE AND CONDUCTIVE POWER SUPPLY IN METALLURGICAL MHD DEVICES
The computations of electromagnetic (EM) and hydrodynamic (HD) fields based on developed 3D model are performed for: i) almost axis-symmetrical MHD-device with bottom and submerged top electrodes with single phase alternating current (AC) and cylindrical coil around the melt; ii) MHD-device with three-phases current supplied over three submerged top electrodes as well as with EM stirrer in form of side non-symmetrical inductor, which produces “travelling” magnetic field. Obtained flow patterns are the results of competition of electro-vortex convection (EVC) and electromagnetic convection (EMC), which appear due to conductive and inductive current supply accordingly. For axissymmetrical MHD-device the melt rotation appears as the effect of intercoupling of inductive or conductive current with magnetic fields, produced by other type of power supply.
Endodontic regeneration: hard shell, soft core
A loss of organs or the destruction of tissue leaves wounds to which organisms and living things react differently. Their response depends on the extent of damage, the functional impairment and the biological potential of the organism. Some can completely regenerate lost body parts or tissues, whereas others react by forming scars in the sense of a tissue repair. Overall, the regenerative capacities of the human body are limited and only a few tissues are fully restored when injured. Dental tissues may suffer severe damage due to various influences such as caries or trauma; however, dental care aims at preserving unharmed structures and, thus, the functionality of the teeth. The dentin–pulp complex, a vital compound tissue that is enclosed by enamel, holds many important functions and is particularly worth protecting. It reacts physiologically to deleterious impacts with an interplay of regenerative and reparative processes to ensure its functionality and facilitate healing. While there were initially no biological treatment options available for the irreversible destruction of dentin or pulp, many promising approaches for endodontic regeneration based on the principles of tissue engineering have been developed in recent years. This review describes the regenerative and reparative processes of the dentin–pulp complex as well as the morphological criteria of possible healing results. Furthermore, it summarizes the current knowledge on tissue engineering of dentin and pulp, and potential future developments in this thriving field.