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We report theoretically and experimentally a passive bidirectional current–voltage ( $I$ – $V$ ) converter, capable of converting input currents into output voltages, and conversely, input voltages into output currents, based on a multiphase heterostructured magnetoelectric (ME) ring. The ME ring has a coil-wound, intermagnetically biased magnetostrictive–piezoelectric (MS–PE) heterostructure, in which an axially polarized PZT PE ceramic ring is bonded between two circumferentially magnetized, intermagnetically biased Terfenol-D short-fiber/NdFeB magnet/epoxy three-phase MS composite rings. In $I$ – $V$ conversion, a current applied to the coil induces a vortex magnetic field to the ME ring, resulting in an open-circuit voltage from the ME ring because of the direct ME effect. In voltage–current ( $V$ – $I$ ) conversion, a voltage applied to the ME ring produces a circumferential magnetic induction due to the converse ME effect, leading to a short-circuit current from the coil. The converter exhibits simultaneously large $I$ – $V$ and $V$ – $I$ conversion factors of $\sim 0.3$ V/A and $\sim 0.2$ mA/V in a broad non-resonance frequency range up to 80 kHz as well as enhanced conversion factors of $\sim 7$ and $\sim 25$ times at the resonance frequency of 122 kHz, respectively. [ABSTRACT FROM PUBLISHER]

This paper proposes a three-phase five legged wound transformer core constructed of two high permeability Si-Fe wound cores and two conventional Si-Fe wound cores. The two large internal wound cores are manufactured of high permeability, grain-oriented electrical steel. The two small outer wound cores are manufactured of conventional, grain-oriented electrical steel. The specific arrangement is based on experimental evidence concerning the peak flux density non-uniformity of the typical three-phase five legged wound transformer core, constructed of the high magnetization grain-oriented steel. Since the peak flux density of the two outer cores is lower than the two internal cores, low cost, low permeability, conventional grain-oriented electrical steel can be used for the outer cores. Losses, excitation currents, flux waveforms, and their harmonics contents are presented in this paper. A comparison of the mixed three-phase transformer core and the typical one is also carried out. [ABSTRACT FROM PUBLISHER]

A human-size magnetic shield of cylindrical structure (inner diameter: 92 cm, length: 220 cm) has been constructed with magnetic shaking enhancement. The weights of the magnetic materials used are 69 kg for Metglas 2705M amorphous tapes and 40 kg for Permalloy tapes and the total weight was about 250 kg. The shielding factor at the center was 4000 for a transverse magnetic field of 10 /spl mu/T, 1 Hz and residual dc magnetic field was as small as 1-2 nT when compensation for open ends was applied. The noise level of the shield measured, when open end compensation was off, by a SQUID magnetometer at the center of the shield was 54 fT//spl radic/Hz at 1 Hz and 23 fT//spl radic/Hz at 10 Hz. [ABSTRACT FROM PUBLISHER]