Discontinuous resistance change and domain wall scattering in patterned NiFe wires with a nanoconstriction

A nonlinear current-voltage (I-V) characteristic was observed in patterned NiFe wires with a central "bow-tie" point contact constriction. By passing a dc current through the wire, a sharp resistance drop was obtained for current densities in the range of 1.1-1.4 x 10(7) A/cm(2). This is attributed to current-induced domain wall drag, resulting in displacement of a domain wall away from the constriction. A maximum current-induced resistance change of 0.079% was obtained for a 100-nm constriction, which is comparable with the magnetoresistance due to domain wall scattering in NiFe

Hybrid HVDC for supply of power to offshore oil platforms

A HVDC hybrid system, comprising a line commutated thyristor HVDC converter and a STATCOM, is proposed in this paper for supplying power to offshore oil platforms that do not have their own generation. The proposed system combines the robust performance, low capital cost and low power loss of a line commutated HVDC converter, with the fast dynamic performance of an equivalent VSC Transmission system. The paper describes the principles and control strategies of the proposed system. PSCAD/EMTDC simulations are presented to demonstrate the robust performance of the system using case studies of various operating conditions such as black-start, load perturbations, AC fault conditions and disturbance caused by the starting of large local induction machines