[Fix] Fix gpu occupying when running with cpu

ppsci/arch/activation.py

@@ -146,7 +146,7 @@ def init_for_hidden_layer(layer: nn.Linear, w0: float = 30):
     "silu": Silu(),
     "sin": Sin(),
     "cos": Cos(),
-    "swish": Swish(),
+    "swish": Swish,
     "tanh": nn.Tanh(),
     "identity": nn.Identity(),
     "siren": Siren(),
@@ -166,4 +166,9 @@ def get_activation(act_name: str) -> Callable:
     if act_name.lower() not in act_func_dict:
         raise ValueError(f"act_name({act_name}) not found in act_func_dict")
 
-    return act_func_dict[act_name.lower()]
+    act_layer = act_func_dict[act_name.lower()]
+    if isinstance(act_layer, type) and act_name != "stan":
+        # Is a activation class but not a instance of it, instantiate manually(except for 'Stan')
+        return act_layer()
+
+    return act_layer

ppsci/utils/symbolic.py

@@ -97,7 +97,7 @@
     sp.Max: paddle.maximum,
     sp.Min: paddle.minimum,
     sp.Abs: paddle.abs,
-    sp.Heaviside: functools.partial(paddle.heaviside, y=paddle.zeros([])),
+    sp.Heaviside: paddle.heaviside,
     sp.sign: paddle.sign,
     sp.ceiling: paddle.ceil,
     sp.floor: paddle.floor,
@@ -214,6 +214,9 @@ def __init__(
         elif self.expr.func == sp.Heaviside:
             self._apply_func = self._heaviside_operator_func
             self._auxiliary_func = SYMPY_TO_PADDLE[sp.Heaviside]
+            self._auxiliary_func = functools.partial(
+                self._auxiliary_func, y=paddle.zeros([])
+            )
         elif self.expr.func == sp.Min:
             self._apply_func = self._minimum_operator_func
         elif self.expr.func == sp.Max: