Correct spelling of Nicolson. Set beta and gamma in GeneralisedAlpha to ensure consistency.

+mafe/FeAnalysisDynamicTD.m

@@ -50,7 +50,7 @@ classdef FeAnalysisDynamicTD < mafe.FeAnalysis
             % ------------------------------------------------------------------
             % scheme identification and settings
             switch (self.scheme)
-               case mafe.TimeIntegrationType.CrankNicholson
+               case mafe.TimeIntegrationType.CrankNicolson
                   %
                   beta  = 0.25;
                   gamma = 0.50;
@@ -101,6 +101,9 @@ classdef FeAnalysisDynamicTD < mafe.FeAnalysis
                   gamma = self.params.gamma;
                   alpha_f = self.params.alpha_f;
                   alpha_m = self.params.alpha_m;
+                  % ensure stability and 2nd order accuracy for given alpha
+                  beta  = 0.25 + 0.50 * ( alpha_f - alpha_m );
+                  gamma = 0.50 + 1.00 * ( alpha_f - alpha_m );
                   %
                   self.params.theta_ = [ 1.0-alpha_f, 1.0-alpha_f, 1.0-alpha_f                 ];
                   self.params.gamma_ = [ 6.0*beta,    2.0*gamma,   (1.0-alpha_m)/(1.0-alpha_f) ];