Propulsion Requirements for High-Speed Vehicles with Electrodynamic Suspension
The thrust force and power requirements for the propulsion of a vehicle with electrodynamic suspension (i.e., using superconducting magnets) are discussed. Acceleration thrust, magnetic drag, and aerodynamic drag are shown to lead to calculated power requirements of 8.0 MW under acceleration, and 5.2 MW for cruising at 300 mi/h. Aerodynamic and magnetic drag forces together produce acceptable passive deceleration characteristics. Propulsion requirements under normal operation and in emergency situations (i.e., unscheduled stops) are described. Propulsion systems are discussed, and it is concluded that the linear synchronous motor is most suitable for the proposed Maglev vehicle.
DESIGN, ANALYSIS AND TEST RESULTS FOR A SUPERCONDUCTING LINEAR SYNCHRONOUS MOTOR
A linear synchronous motor has been designed to propel a 480 km/h magnetically levitated passenger vehicle. The paper describes the motor and presents results of tests which have been performed on essentially full-scale components of the motor using a 7.6 m-diameter test-wheel facility. Controlled starting, acceleration, cruising, deceleration and transient operation have been demonstrated. A 6-component force balance has been used to measure the three forces and three moments acting on a single stationary superconducting magnet due to its interaction with the split 3-phase windings mounted on the rim of the test wheel and energized by a variable-frequency current-controlled inverter power supply. Measured forces and terminal characteristics over complete cycles of force angle are claimed to be in agreement with analysis based on a coupled circuit model of the machine and mutual inductance computations. Moments were measured to be small under all operating conditions. Two modes of control have been demonstrated. The alpha -scheme, proposed for a full-scale system, maintains the angle between induced voltage and phase current at a value which optimizes the motor characteristics, i.e. inverter Mva rating, etc. beta- control, which may be required for starting, uses vehicle position detectors to fire the inverter thyristors at appropriate times.
Stereoselective disposition of ibuprofen enantiomers in infants.
The pharmacokinetics of the enantiomers of ibuprofen were investigated after oral administration of a single 7.6 +/- 0.3 mg kg-1 dose of the racemate in 11 infants. Mean (+/- s.d.) half-lives were 1.6 +/- 0.5 h for S(+) and 1.5 +/- 0.5 h for R(-) and mean (+/- s.d.) AUC values were 31.5 +/- 14.3 mg l-1 h for S(+) and 36.6 +/- 13.8 mg l-1 h for R(-). Since plasma concentrations of the active S(+)-isomer were lower than those reported in adults, a higher dosage might be required in infants.