Christopher G Seaman

48140503, Mar 21, 1989

Nov 18, 1987

7/122190

William D. McGraw - Monroeville PA
Kevin G. Christian - Brookline MA
William M. Hall - Lower Burrell PA
Gene S. Miller - Maryville TN
Christopher M. Seaman - Troy NY
Robert L. Kozarek - Apollo PA

Aluminum Company of America - Pittsburgh PA

C25C 306

204 67

A method of estimating and controlling the concentration of alumina in the bath of a Hall cell. The method includes the use of an estimator that employs two sets of equations, namely, a time update algorithm that contains a dynamic model of the alumina mass balance of the cell and provides estimates of alumina concentration, and a measurement algorithm that uses a process feedback variable from the cell to modify the alumina estimate. In addition, the method includes the use of one or more tuning parameters, such as state noise variance and measurement noise variance. The measurement noise variance is modified by the process noise variance in a manner that increases measurement noise variance for high values of process noise and decreases measurement noise variance for low values of process noise. In addition, one or more of the parameters of the model are modified by the feed history of the cell.

56744161, Oct 7, 1997

Aug 28, 1995

8/520203

Edward P. Patrick - Murrysville PA
Philip J. Blakeley - Cambridge, GB
Regis J. Huth - Cabot PA
A. Victor Pajerski - New Kensington PA
Christopher M. Seaman - Jeannette PA
Donald J. Spinella - Mt. Pleasant PA
Charles B. Wolf - Irwin PA

Aluminum Company of America - Pittsburgh PA

B23K 904

219123

A method and apparatus for graining a surface having a substantial area traveling at a substantial rate of speed. The method includes directing the surface past an array of electrical arcs traveling about a plurality of loop electrodes arranged to provide overlapping arc loop paths as the surface travels past the array of arc loops. The arc loops are established between the loop electrodes and the traveling surface, and thus contact the surface to grain the same. When each arc is struck between its loop electrodes and traveling surface, it is magnetically impelled about the loop of its electrode by a magnetic field established perpendicular of the direction of arc current flow. An annular sheath of gas is provided on each side of the electrode loop and the arc struck between the electrode loop and the traveling surface.