Magneto-thermal-fluid analysis taking account of natural convection using semi-Lagrange coordinate system

A method for magneto-thermal-fluid analysis, taking account of natural convection using a semi-Lagrange coordinate system, is developed. The developed method is applied to a simple induction heating model in which the steel plate is heated due to an eddy current. It is shown that the result, considering the convection in air, is different from the result neglecting it</p

Investigation of effectiveness of various methods with different unknown variables for 3-D eddy current analysis

Computer codes using the A-&#966;, A-&#966;-&#937;, A*-0&#937;-E, T-&#937;, and E-&#937; methods were developed. The effects of the volume ratio of the conductor region to the whole region, the shape of the conductor, and the ratio of the hole region to the conductor region on the computer storage, the CPU time, and the accuracy of the methods are investigated systematically using a few simple models. The effect of the conductivity of the conductor is also examined. The computer storage, the CPU time, and the error are found to increase with increase of the volume ratio of the conductor region to the whole region. The computer storage and the CPU time are affected by the shape of the conductor in some methods of analysis. The error of the A*-&#937;(E-&#937;) method is larger than that of the other methods</p

Practical analysis of 3-D dynamic nonlinear magnetic field using time-periodic finite element method

A practical 3-D finite element method using edge elements for analyzing stationary nonlinear magnetic fields with eddy currents in electric apparatus, in which the flux interlinking the voltage winding is given, has been proposed. The method is applied to the analysis of magnetic fields in the Epstein frame </p

Method for determining relaxation factor for modified Newton-Raphson method

In order to reduce the CPU time for the modified Newton-Raphson method which introduces a relaxation factor, the effect of the relaxation factor on the residual of the Galerkin method is examined in detail. It is shown that a relaxation factor which always provides convergent solutions can be easily searched. Various methods of searching for the relaxation factor to be used are compared </p

Magnetostriction measurements with a laser Doppler velocimeter

A new method for measuring the magnetostriction of silicon steel sheet using a laser Doppler velocimeter has been developed. This method has the following advantages: (a) non-contact measurement, (b) better resolution (less than 4×10-8 m under the condition that the error is within 1%) than conventional methods, (c) measurement of magnetostriction in any direction of anisotropic material and (d) little operator skill required </p

Comparison of various methods of analysis and finite elements in 3-D magnetic field analysis

In order to evaluate the most suitable method of analysis (A- phi or T- Omega method) and finite element (nodal or edge element) for a given problem, the features of each method and element have been investigated. The accuracy, computer storage, and CPU time of each method and element are compared for a 3-D nonlinear magnetostatic model and a 3-D eddy current model. The flux and eddy current densities calculated are compared with those measured. It is shown that the accuracy and the CPU time of the edge element are better than those of the nodal element. The A- phi method is better than T- Omega method for nonlinear problems from the viewpoint of convergence characteristics of nonlinear iterations.</p

Rotigotine suppresses sleep-related muscle activity augmented by injection of dialysis patients’ sera in a mouse model of restless legs syndrome

Idiopathic restless legs syndrome (RLS) has a genetic basis wherein BTBD9 is associated with a higher risk of RLS. Hemodialysis patients also exhibit higher rates of RLS compared with the healthy population. However, little is known about the relationship of BTBD9 and end-stage renal disease to RLS pathophysiology. Here we evaluated sleep and leg muscle activity of Btbd9 mutant (MT) mice after administration of serum from patients with either idiopathic or RLS due to end-stage renal disease (renal RLS) and investigated the efficacy of treatment with the dopamine agonist rotigotine. At baseline, the amount of rapid eye movement (REM) sleep was decreased and leg muscle activity during non-REM (NREM) sleep was increased in MT mice compared to wild-type (WT) mice. Wake-promoting effects of rotigotine were attenuated by injection of serum from RLS patients in both WT and MT mice. Leg muscle activity during NREM sleep was increased only in MT mice injected with serum from RLS patients of ideiopatic and renal RLS. Subsequent treatment with rotigotine ameliorated this altered leg muscle activity. Together these results support previous reports showing a relationship between the Btbd9/dopamine system and RLS, and elucidate in part the pathophysiology of RLS

Effect of continuity of potential on accuracy in magnetic field analysis using nonconforming mesh

Methods of analyzing magnetic fields in rotating machines using nonconforming meshes, in which only an interpolation technique is applied, are investigated. The effect of the continuity of potentials at nonconforming surfaces on accuracy is examined, it is shown that although the flux distribution is not affected by the discontinuity of the potential, the force and torque are fairly affected by the discontinuity. Therefore, it is shown that a continuous method, or a discontinuous method using a fine mesh should be used especially in force and torque calculation. An analysis of an induction motor is also carried out using a nonconforming mesh</p