diff --git a/crates/applications/stacked_cores/scripts/inverter_characteristics.py b/crates/applications/stacked_cores/scripts/inverter_characteristics.py
index 8b95b56..e74a946 100755
--- a/crates/applications/stacked_cores/scripts/inverter_characteristics.py
+++ b/crates/applications/stacked_cores/scripts/inverter_characteristics.py
@@ -90,6 +90,39 @@ class Piecewise:
     def plot_equilibrium(self, from_: float = 0.0, to: float = 1.0, title: str = "Piecewise"):
         self.plot_for(from_, to, title, self.get_repeated)
 
+fwd_17_4_0_8e10 = Piecewise(
+    [
+        [ -16381,   6688 ],
+        [ -15885,   6778 ],
+        [ -14831,   6878 ],
+        [ -13622,   7004 ],
+        [   -883,   8528 ],
+        [   6252,   9496 ],
+        [   7846,   9703 ],
+        [   8148,   9766 ],
+        [   8425,   9831 ],
+        [   8705,   9892 ],
+        [   8988,   9916 ],
+        [   9866,  10114 ],
+        [  11179,  10234 ],
+        [  12033,  10382 ],
+        [  12491,  10422 ],
+        [  13135,  10494 ],
+        [  14363,  10649 ],
+    ]
+).normalized(17000)
+
+fwd_18 = Piecewise(
+    [
+        [ -16206, -1131 ],
+        [ -15192,  -746 ],
+        [ -12827,    33 ],
+        [   -642,  4990 ],
+        [  13082,  9652 ],
+        [  16696, 10600 ],
+    ]
+).normalized(17000)
+
 
 fwd_24 = Piecewise(
     [
@@ -375,6 +408,7 @@ inv_39_2_0_15e10 = Piecewise(
 ).normalized(17000)
 
 for (name, curve) in [
+    ("18", fwd_18.logically_inverted()),
     # ("24", fwd_24.logically_inverted()),
     # ("26", fwd_26.logically_inverted()),
     # ("38 1:0 (2e10 I)", fwd_38_1_0.logically_inverted()),
@@ -393,4 +427,4 @@ for (name, curve) in [
 ]:
     curve.plot(title = f"{name} mapping")
     curve.logically_inverted().plot_slope(title = f"{name} slope")
-    # curve.plot_equilibrium(title = f"{name} equilibrium")
+    curve.plot_equilibrium(title = f"{name} equilibrium")
diff --git a/crates/applications/stacked_cores/scripts/stacked_cores_39xx.py b/crates/applications/stacked_cores/scripts/stacked_cores_39xx.py
index c9601a3..9612167 100755
--- a/crates/applications/stacked_cores/scripts/stacked_cores_39xx.py
+++ b/crates/applications/stacked_cores/scripts/stacked_cores_39xx.py
@@ -8,23 +8,23 @@ import sys
 
 from stacked_cores import load_csv, labeled_rows, last_row_before_t, extract_m
 
-def extract_one(path: str):
+def extract_one(path: str, t_first: float, t_last: float):
     header, raw_rows = load_csv(path)
     rows = labeled_rows(header, raw_rows)
 
-    tx_init = last_row_before_t(rows, 2e-9)
-    tx_fini = last_row_before_t(rows, 3e-9)
+    tx_init = last_row_before_t(rows, t_first)
+    tx_fini = last_row_before_t(rows, t_last)
     m_init = extract_m(tx_init)
     m_fini = extract_m(tx_fini)
 
     return m_init[0], m_fini[-1]
 
-def extract_39xx(base_path: str):
+def extract_39xx(base_path: str, t_first: str = "2e-9", t_last: str = "3e-9"):
     base_dir, prefix = os.path.split(base_path)
     mappings = []
     for entry in os.listdir(base_dir):
         if entry.startswith(prefix):
-            (input_, output) = extract_one(os.path.join(base_dir, entry, "meas.csv"))
+            (input_, output) = extract_one(os.path.join(base_dir, entry, "meas.csv"), float(t_first), float(t_last))
             mappings.append((input_, output))
 
     print("Piecewise(")
@@ -36,4 +36,4 @@ def extract_39xx(base_path: str):
 
 
 if __name__ == '__main__':
-    extract_39xx(sys.argv[1])
+    extract_39xx(*sys.argv[1:])