Abstract: A method for using ferromagnetic shims to reduce the inhomogeneity of the magnetic field in a Diameter Spherical Volume (DSV) in the bore of a Magnetic Resonance Imaging (MRI) device is provided. More specifically, a magnetic field is established within the bore of the MRI device. An operator defines the DSV. The strength of the magnetic field is measured at the surface of the DSV. A Legendre polynomial is derived to model the inhomogeneity in the magnetic field in the DSV. A set of coefficients for the harmonic terms of the polynomial is calculated from the field strength measurements and segregated into three separate groups for evaluation. Each group of terms expresses field inhomogeneity in a unique set of spatial dimensions.

Abstract: A switch comprises a length of superconductive wire having a plurality of normally conductive stabilizing segments thereon.

Abstract: An interdigital electrode transducer mounted on an acoustic surface wave propagating medium having an output proportional to an Nth order derivative of the surface acoustic waves propagating in the medium. The Nth order derivative, where N is any real, positive number, is obtained by using a finite difference approximation. The transducer finger pairs are biphase coded and amplitude weighted in order to detect the proper combination of signal differences for the approximation and thereby indicate the desired derivative.