Volume 19, Issue 3, March 1948
Index of content:
19(1948); http://dx.doi.org/10.1063/1.1741227View Description Hide Description
Several details are described in the preparation of capillary tubes for x‐ray power specimens which greatly facilitate the synthesis of such tubes and their subsequent removal from the pilot wire. The over‐all method employed is essentially that of Fricke et al. Wires of 22‐gauge copper, after annealing in an atmosphere of helium, are cleaned and dipped into the cellulose acetate solution by means of a crank‐driven rack. The rate of withdrawal determines the wall thickness. A method is given for centering the filled specimen tubes precisely in the powdercamera by the use of a centering jig.
19(1948); http://dx.doi.org/10.1063/1.1741228View Description Hide Description
19(1948); http://dx.doi.org/10.1063/1.1741229View Description Hide Description
A feed‐back method is described which is suitable for an automatic computer solving linear simultaneous equations and secular equations. This method is more general than is the Gauss‐Siedel method. The design for an analog computer based on this feed‐back method is outlined. This design utilizes resistive voltage dividers to represent coefficients and voltages to represent the variables. The variables are automatically adjusted by the feed‐back system. The performance obtained on a 4‐equation model is given. Usually an accuracy of better than one percent is obtained.
19(1948); http://dx.doi.org/10.1063/1.1741230View Description Hide Description