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

New technique for producing a strong multi-pole magnet

A new technique for producing strong multipole magnet is developed. A cylindrical magnet oriented with its easy axis of magnetization perpendicular to the cylinder axis is magnetized by a multipole magnetizer. This procedure results in a multipole magnet with a flux density almost sixty percent greater than the flux density produced by a multi-pole magnet which is not oriented. The technique is especially effective for producing small cylindrical magnets with many poles and agreement of a theoretical analysis with experimental results is very good, with deviations of no more than a few percent.</p

An improved method for determining the DC magnetization curve using a ring specimen

When the DC magnetization curve (B-H) of nonoriented material is measured in a ring specimen, there is an intrinsic error due to the assumption that the mean magnetic path length is equal to the mean geometric path length. A novel method for determining the B-H curve accurately is proposed. The validity of the method is verified by experiments</p

Optimal design of injection mold for plastic bonded magnet

The optimal design of an injection mold for producing a stronger multipole magnet is carried out using the finite element method and the direct search method. It is shown that the maximum flux density in the cavity obtained by the optimal design is about 2.6 times higher than that of the initial shape determined empirically. 3-D analysis of the nonlinear magnetic field in the injection mold with complicated structure is also carried out. The calculated flux distribution on the cavity surface is in good agreement with the measured one</p

Off-Road Vehicular Destabilization of Hillslopes: The Major Contributing Factor to Destructive Debris Flows in Ogden, Utah, 1979

A severe rain storm on August 11 and 18, 1979, caused major flood damage in urban areas of east Ogden, Utah. At least 3.85 cm of rain fell in a 7 hour-period. The severity of damage was dramatically increased by water diverted from the Brigham-Ogden Canal, when it was clogged by a debris flow in the vicinity or Third, Taylor, and Polk Streets (Fig. 1). The purpose or this investigation is to ascertain the sequence of events that followed the storm, and to quantify the processes insofar as possible. An inspection of the area on September 21-25, 1979 , and the subsequent study, indicated that the principal cause or damage was a combination of two factors: (1) channelization or runoff and erosion of off-road vehicle (ORV) trails clogged the Brigham-Ogden Canal, and (2) the diverted canal water eroded a notch in the alluvial fan and terrace deposits below, which then combined with the debris eroding from the ORV trails to bury downslope structures

Simulating typical entanglement with many-body Hamiltonian dynamics

We study the time evolution of the amount of entanglement generated by one dimensional spin-1/2 Ising-type Hamiltonians composed of many-body interactions. We investigate sets of states randomly selected during the time evolution generated by several types of time-independent Hamiltonians by analyzing the distributions of the amount of entanglement of the sets. We compare such entanglement distributions with that of typical entanglement, entanglement of a set of states randomly selected from a Hilbert space with respect to the unitarily invariant measure. We show that the entanglement distribution obtained by a time-independent Hamiltonian can simulate the average and standard deviation of the typical entanglement, if the Hamiltonian contains suitable many-body interactions. We also show that the time required to achieve such a distribution is polynomial in the system size for certain types of Hamiltonians.Comment: Revised, 11 pages, 7 figure

Recent progress in numerical analysis for electromagnetic devices

Over the past ten years, the ability of computers has progressed rapidly, and techniques of numerical analysis have improved vastly. The 3D analysis of electrostatic and magnetostatic fields can easily be carried out on a workstation, and results obtained contribute to the design and development of new products. The main factors of progress in numerical analysis using the finite-element method are reviewed.</p

On a generalization of the global attractivity for a periodically forced Pielou's equation

In this paper, we study the global attractivity for a class of periodic difference equation with delay which has a generalized form of Pielou's difference equation. The global dynamics of the equation is characterized by using a relation between the upper limit and lower limit of the solution. There are two possible global dynamics: zero solution is globally attractive or there exists a periodic solution which is globally attractive. Recent results by Camouzis and Ladas [Periodically forced Pielou's equation, J. Math. Anal. Appl. 333 (1) (2007) 117-127] are generalized. Two examples are given to illustrate our results