diff --git a/opensbt/algorithm/nsga2dt_optimizer.py b/opensbt/algorithm/nsga2dt_optimizer.py
index bd34ab4..fc897de 100644
--- a/opensbt/algorithm/nsga2dt_optimizer.py
+++ b/opensbt/algorithm/nsga2dt_optimizer.py
@@ -128,8 +128,8 @@ def run(self) -> SimulationResult:
             pop_size=None,
             n_offsprings=None,
             sampling = select_operator("init", config),
-            crossover = select_operator( "cx", config),
-            mutation = select_operator( "mut", config),
+            crossover = select_operator( "cx", config, **{"eta" : eta_crossover, "prob" : prob_crossover}),
+            mutation = select_operator( "mut", config, **{"eta" : eta_mutation, "prob" : prob_mutation}),
             eliminate_duplicates = select_operator( "dup", config),
             archive=MemoryArchive()
         )
@@ -157,12 +157,12 @@ def run(self) -> SimulationResult:
                     pop_size=pop_size,
                     n_offsprings=num_offsprings,
                     sampling=initial_population,
-                    crossover = select_operator("cx",config),
-                    mutation = select_operator("mut", config),
+                    crossover = select_operator( "cx", config, **{"eta" : eta_crossover, "prob" : prob_crossover}),
+                    mutation = select_operator( "mut", config, **{"eta" : eta_mutation, "prob" : prob_mutation}),
                     eliminate_duplicates = select_operator( "dup", config),
                     archive=MemoryArchive()
                  )
-
+                print(select_operator("mut", config))
 
                 termination = get_termination("n_gen", inner_num_gen)
 
diff --git a/opensbt/algorithm/pso_optimizer.py b/opensbt/algorithm/pso_optimizer.py
index 3649d9d..edb3a68 100644
--- a/opensbt/algorithm/pso_optimizer.py
+++ b/opensbt/algorithm/pso_optimizer.py
@@ -41,8 +41,6 @@ def __init__(self,
 
         # initialize algorithm
         self.algorithm = PSO(
-            pop_size=config.population_size,
-            archive = MemoryArchive(),
             pop_size = config.population_size,
             sampling = select_operator("init",config),
             archive = MemoryArchive()
diff --git a/opensbt/utils/operators.py b/opensbt/utils/operators.py
index bd35a9e..f074900 100644
--- a/opensbt/utils/operators.py
+++ b/opensbt/utils/operators.py
@@ -8,9 +8,6 @@ def select_operator(operation,
     """
     Selects either the default operator or a custom operator based on the condition.
     """
-    if kwargs is not None:
-        kwargs = {}
-        
     if config.operators[operation] is None:
         if operation == "mut":
             operator = PM