Tom Fredman

• Åbo Akademi University

A boundary identification problem in inverse heat conduction is studied, based on data from internal measurement of temperature and heat flux. Formulated as a sideways heat conduction equation, a spatial continuation technique is applied to extend the solution to a known boundary condition at the desired boundary position. Recording the positions t...

The process of heat transfer in the steelmaking ladle refractories was investigated. Several techniques of modeling the heat loss were also discussed. Processes from continuous casting to optics were scheduled in the design of physical models. The thermal condition of the system was evaluated by thoroughly analyzing the experimental observations. H...

An analytical solution method for composite layer diffusion in cylindrical geometry is studied, relying on local analytical solutions for the single material layers combined with a numerical solution scheme for the material boundary states. The one-layer submodel was formulated for one-dimensional geometry and constant material properties. An effic...

A survey of the literature dealing with the diagnosis, modeling and control of accretions on the inner wall of the blast furnace stack is presented. Blast furnace operation is sensitive to irregularities in accretion build-up on the refractory inside the stack (or shaft as it is sometimes termed). In order to protect the refractory lining and embed...

We study boundary movement identification for a parabolic partial differential equation describing a dynamic diffusion process, on basis of internally recorded data. Formulated as a sideways diffusion equation, the problem is treated by a spatial continuation technique to extend the solution to a known boundary condition at the desired boundary pos...

We study boundary movement identification in inverse heat conduction, on the basis of data from internal measurement of temperature and heat flux. Formulated as a sideways heat conduction equation, the problem is treated by a spatial continuation technique to extend the solution to a known boundary condition at the desired boundary position. Record...

A survey of the literature dealing with factors behind the formation of accretions on the inner wall of the blast furnace stack is presented. Blast furnace operation is sensitive to irregularities in accretion build-up on the refractory inside the stack (or shaft as it is sometimes termed). In order to protect the refractory lining and embedded coo...

Formation of accretions at some point in the lining campaign of the blast furnace was investigated. A model of accretion layer thickness in the blast furnace stack was studied. A simple one-dimensional, dynamic model was formulated on basis of the sideways heat equation in the refractory region and steady state approximation in the accretion region...

The heat conduction in the multilayer lining of a steelmaking ladle is treated by a semi-analytical solution method for composite layer heat conduction in cylindrical geometry. The technique is based on local analytical solutions for the single material layers combined with a numerical solution scheme for the material boundary temperatures. Develop...

A two-dimensional mathematical model of steelmaking ladles is presented. The model can be used as a design tool, by which a number of variables such as holding time, material choice, and refractory layer thicknesses can be studied with regard to their influence on the steel temperature evolution during casting. In addition, the model can act as a d...

Modeling of the transient thermal state of metallurgical ladels is motivated by the need for estimating the drop in temperature of the liquid metal in the ladle. On-line estimation of the state is required, since the same ladle is used in a number of casting cycles with rapid changes in boundary conditions for the temperature field, and the conditi...

A two-node fully recurrent neural network producing oscillations is analysed. The network has no true inputs and the outputs from the network exhibit a circular phase portrait. The weight configuration of the network is investigated, resulting in analytical weight expressions. The theoretical predictions are compared with numerical weight estimates...

A recurrent two-node neural network producing oscillations is analyzed. The network has no true inputs and the outputs from the network exhibit a circular phase portrait. The weight configuration of the network is investigated, resulting in analytical weight expressions, which are compared with numerical weight estimates obtained by training the ne...

A mathematical model suitable as a tool for improving temperature control in the steel plant is presented. With this tool, a number of variables such as holding time, material choice and refractory layer thicknesses can be studied with regard to their influence on the steel temperature evolution during casting. In addition, the model can be used as...

Diss. -- Åbo Akademi.