Forces of rails for electromagnetic railguns

In this paper, using electromagnetic theory, the equations for the total magnetic force on the rails are deduced. Besides this, the equations for the changes of the magnetic force along with time and the running position of the armature under jointed pulse operating current are presented. Then, the equations for changes of the bending stress and shear stress in the rail along with time and the running position of the armature are given. Changes of the magnetic force distribution between the two rails along with the running position of the armature and other parameters are investigated. The total electromagnetic forces on the rail under jointed pulse operating current are analyzed. Distribution and changes of the bending stresses in the rail are studied. A number of results are obtained. The results are useful for design and application of the railgun system.     

Design and analysis of a novel inset permanent magnet synchronous motor

This paper presents the design of a permanent magnet (PM) synchronous motor with the magnets laid flush in slots let into the rotor surface, called inset magnet rotor. The finite element field analysis coupled with the drive circuit equations are briefly discussed for obtaining the motor performance. Experimental results obtained are in good agreement with the finite element analysis.     

Power-Central Elements in Tensor Products of Symbol Algebras

Let A be a central simple algebra over a field F. Let k₁,…, k_r be cyclic extensions of F such that k₁ ?_F… ?_Fk_r is a field. We investigate conditions under which A is a tensor product of symbol algebras where each field k_i lies in a symbol F-algebra factor of the same degree as k_i over F. As an application, we give an example of an indecomposable algebra of degree 8 and exponent 2 over a field of 2-cohomological dimension 4.