Fix bug in MGA code

Normalized sector MGA algorithm did not work previously because the instance name was incorrect. Now fixed. Also updated the comment related to the integer weighting method.

Author: jdecarolis

Diff for: temoa_model/temoa_mga.py

@@ -44,9 +44,7 @@ def SlackedObjective_rule ( M, prev_cost, mga_slack ):
 def PreviousAct_rule ( instance, mga_weight, prev_activity_t ):
 	#   The version below weights each technology by its previous cumulative
 	#   activity. However, different sectors may be tracked in different units and 
-	#   have activities of very different magnitudes. Can also modify the code 
-	#   changing 'val' to 1 to implement a integer-based weight to address this non-uniform
-	#   weighting issue.
+	#   have activities of very different magnitudes. 
 
 	epsilon=1e-6
 
@@ -55,7 +53,7 @@ def PreviousAct_rule ( instance, mga_weight, prev_activity_t ):
 			if t in instance.tech_mga:
 				val = value( instance.V_ActivityByTech[t] )
 				if abs(val) < epsilon: continue
-				prev_activity_t[ t ] += 1.0   #val
+				prev_activity_t[ t ] += 1.0
                	return prev_activity_t
 
 	#   The version below calculates activity by sector and normalized technology-
@@ -76,7 +74,7 @@ def PreviousAct_rule ( instance, mga_weight, prev_activity_t ):
 		  		for S_t in techs[s]
 				)
 
-		for t in instance_1.V_ActivityByTech:
+		for t in instance.V_ActivityByTech:
 			for s in sectors:
 				if t in techs[s]:
 					val = value( instance.V_ActivityByTech[t] )