On the continuity of the magnetizing current density in 3-D magnetic field analysis with edge element

The effects of the continuity of the magnetizing current density on the convergence of the incomplete Cholesky conjugate gradient method and the accuracy of the calculated flux densities are investigated by imposing different continuity conditions for both nodal and edge elements. It is shown that the continuity condition should be imposed precisely in the case of edge elements </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

Investigation of simulated annealing method and its application to optimal design of die mold for orientation of magnetic powder

Factors affecting the convergence characteristics and results obtained by the optimal design method using the finite element method and simulated annealing are investigated systematically, and the optimal parameters for simulated annealing method are obtained. The optimal shape of the die mold for orientation of the magnetic powder (nonlinear magnetostatic problem) is obtained using finite elements and simulated annealing. The experimental verification is also carried out </p

Effects of residual magnetism due to minor loop on magnetic property of permanent magnet type of MRI

Summary form only given. The flux distribution of a permanent magnet type of MRI shown in Fig.1 is affected by the hysteresis (minor loop) and eddy currents in the pole piece and yoke due to the pulse current (Fig.2) of the gradient coil. In this paper, the effects of the hysteresis and the eddy current in the yoke on the residual flux density of the probe coil are investigated. It can be assumed that the eddy current does not flow in the pole piece because it is divided into pieces. The eddy current flows in the yoke. Fig.3 shows the change of residual flux density /spl Delta/B/sub z/ at the point S(0,0) in Fig.1. /spl Delta/B/sub z/ is given by /spl Delta/B/sub z/=B/sub z1/-B/sub z0/ (1), where B/sub z0/ is the flux density at the instant t=0(I=0A). B/sub z1/ is the flux density at the instant t=i(I=0A). The instant of 1,2,3,... in Fig.2 corresponds to 1,2,3,... in Fig.3. Fig.3 shows that the hysteresis in the pole piece and yoke should be taken into account. The effect of eddy current in the yoke on the residual flux density /spl Delta/B/sub z/ is not negligible. These results suggests that the reduction of the amplitudes of minor loop and eddy current is important in order to improve the operating characteristics of the permanent magnet type of MRI.</p

Effect of minor loop on magnetic characteristics of permanent magnet type of MRI

A modeling technique of the minor loop using typical hysteresis loops is shown. The effect of the minor loop and eddy current in the pole piece of a permanent magnet type of MRI on the residual flux density of the probe coil is examined. It is illustrated that the change &#916;B of residual flux density occurs due to the minor loop of the pole piece. It is also pointed out that the choice of time interval &#916;t is important in a nonlinear analysis considering the minor loop</p

Analysis of the magnetic property of a permanent-magnet-type MRI - Behavior of residual magnetization

The minor loops of B and H of steel due to pulse excitation and eddy currents induced in steel affect the magnetic characteristics of a permanent-magnet-type MRI. In this paper, the magnetic properties of a permanent magnet assembly is examined by using the finite-element method taking into account minor loop. The distribution of residual magnetization in the yoke is illustrated, and the effect of residual magnetization on the behavior of residual flux density is examined. It is shown that the behavior of B and H in minor loops is affected by the eddy currents in the yoke and pole piece.</p

Analysis of students’ mathematical achievement in grades 3 and 6 in Uganda: Factors affecting test scores and curriculum performance

This study aims at determining factors affecting students’ mathematical achievement based on the curriculum, and finding out common errors and the reasons for them. Tests and questionnaires were conducted on grade 3 and grade 6 students. The results revealed: (1) the number of meals, living with mother, and socio-economic status (radio, table and kerosene lamp) positively affected scores in grade 3 and living with younger sisters negatively affected scores in grade 6, (2) student achievement was different in the contents of the curriculum, and (3) students were not able to solve applied questions without acquiring cognitive skills.3rd World Conference on Learning, Teaching and Educational Leadership (WCLTA-2012

Octacosanol Attenuates Disrupted Hepatic Reactive Oxygen Species Metabolism Associated with Acute Liver Injury Progression in Rats Intoxicated with Carbon Tetrachloride

We examined whether octacosanol, the main component of policosanol, attenuates disrupted hepatic reactive oxygen species metabolism associated with acute liver injury progression in rats intoxicated with carbon tetrachloride (CCl4). In rats intoxicated with CCl4 (1 ml/kg, i.p.), the activities of serum transaminases increased 6 h after intoxication and further increased at 24 h. In the liver of CCl4-intoxicated rats, increases in lipid peroxide (LPO) concentration and myeloperoxidase activity and decreases in superoxixde dismutase activity and reduced glutathione (GSH) concentration occurred 6 h after intoxication and these changes were enhanced with an increase in xanthine oxidase activity and a decrease in catalase activity at 24 h. Octacosanol (10, 50 or 100 mg/kg) administered orally to CCl4-intoxicated rats at 6 h after intoxication attenuated the increased activities of serum transaminases and the increased hepatic myeloperoxidase and xanthine oxidase activities and LPO concentration and the decreased hepatic superoxide dismutase and catalase activities and GSH concentration found at 24 h after intoxication dose-dependently. Octacosanol (50 or 100 mg/kg) administered to untreated rats decreased the hepatic LPO concentration and increased the hepatic GSH concentration. These results indicate that octacosanol attenuates disrupted hepatic reactive oxygen species metabolism associated with acute liver injury progression in CCl4-intoxicated rats

Improvement of convergence characteristic of ICCG method for the A-&#966; method using edge elements

The effect of the scalar potential &#966; in the A-&#966; method on the convergence characteristic of the incomplete Cholesky conjugate gradient (ICCG) method using the edge element is investigated. Several 3-D eddy current models are analyzed both by taking into account &#966; and neglecting &#966; to compare the convergence characteristics. It is illustrated that the CPU time using &#966; is less than ½ of that neglecting &#966;, and there are some models in which the use of &#966; enables us to obtain convergent solutions </p