Toshiya Morisue

Analysis of a coupled problem: the FELIX cantilevered beam

A coupling between the eddy currents and beam deflection of the FELIX cantilevered beam is analyzed using the stream function, Biot-Savarts law and eigenfunction-expansion method. Computed results agree well with experimental results obtained at the Argonne National Laboratory as well with results obtained using the network mesh method. The problem considered is one of the benchmark problems defined by the TEAM Workshop. >

Adaptive on-line optimizing control for lactic acid fermentation

Abstract The adaptive on-line optimization strategy was applied for continuous lactic acid fermentation. The control objective was to maximize the lactate production rate while keeping the lactate concentration at a specified value. The control task was divided into two. The task of the upper layer in the hierarchical control scheme was to search for the optimal operating point for cell concentration, while the task of the lower layer was to make the cell and lactate concentrations follow the respective set points which were either specified or given from the upper layer. The cell and lactate concentrations were either measured on-line or estimated every 2 min. The bioreactor was equipped with a hollow-fiber module, and control was implemented by manipulating the draw-off rate through the filter and the bleed stream flow rate in an on-off manner. It was experimentally shown that productivity as high as 20 kg/m 3 ·h could be attained and maintained for about 40–50 h when the lactate concentration was kept at either 20 kg/m 3 or 30 kg/m 3 .

Electric charges induced in an eddy current field

In almost every eddy current problem, there exist induced electric charges due to the spatial change of conductivity. Therefore, the algorithm of calculating eddy currents should at the same time calculate the induced electric charges because the eddy current field is not only a magnetic field but also an electric field. In this paper, a Lorentz-Coulomb gauge magnetic vector potential formulation is presented, which calculates both eddy currents and induced electric charges. >

3-D magnetostatic field calculation for a magnetic circuit with no (a narrow) air gap

Noting that 3-D magnetostatic field calculations for gapless magnetic circuits are strongly affected by the discretization, the author analyzes this effect for an iron torus using a boundary integral equation based on the surface magnetization current method. The main cause of computational error is the imperfect cancellation of the permeability-free terms in the boundary integral equation due to the improper size of the analytical integration region containing a singular point. A method of reducing the computational error is presented and verified to be valid. >

Analysis of electrically induced flows in DC electric arc furnace

Limitations of natural resources and environmental pollution problems have forced people to consider seriously about recycling of materials. As a means of recycling, DC arc furnaces can be used to recycle scrap materials and already some industries have started to use them in small scale production. An in depth understanding of the process involved is essential for optimal design and efficient control. Therefore, in order to have a better understanding of the process, the authors developed a mathematical model and the model equations are numerically solved. Volume of fluid method is used to treat the free surface. Numerical results show that a single vortical region is generated within the melt when the bottom electrode diameter is large. When the bottom electrode diameter is small, two vortical regions are found with opposite rotation. It is also found that the volume of fluid method can give a more detailed picture of the flow near the surface below the top electrode.

The Lorentz gauge vector potential formulation for the boundary integral equation method

The boundary integral equation method is based on either the Poisson equation (for static problems) or the Helmholtz equation (for dynamic problems). For 3D eddy current calculations using the BIEM, the Lorentz gauge is most suitable since the Maxwell equations reduce to the Helmholtz equations under the Lorentz gauge. In this paper, the Lorentz gauge magnetic vector potential formulation, which yields a unique solution to the problem considered, is presented and numerically tested. It may be concluded from the computed results that the Lorentz gauge formulation and the Coulomb gauge formulation give almost the same computational accuracy, and the former is superior to the latter in terms of computation time and easiness of computer coding. >

A consideration on thecomputational error of the boundary integral equation method for magnetostatic field problems

The computational error has been investigated for three mathematically equivalent methods: (1) the magnetic vector potential method based on the scalar Greens theorem, (2) the magnetic vector potential method based on the vector Greens theorem, and (3) the surface magnetization current method. The application is the magnetostatic field problem of a gapless magnetic circuit like in a transformer in which a large computational error is anticipated. It is found that the numerical error varies from method to method even when the same number and type of boundary elements and the same numerical integration method are used, and is generated mainly by the imperfect cancellation of the permeability-free terms in the boundary integral equation. Two methods for reducing the computational error are presented. >