diff --git a/build/lib/opstool/__about__.py b/build/lib/opstool/__about__.py
index 3d18726..906d362 100644
--- a/build/lib/opstool/__about__.py
+++ b/build/lib/opstool/__about__.py
@@ -1 +1 @@
-__version__ = "0.5.0"
+__version__ = "0.6.0"
diff --git a/build/lib/opstool/preprocessing/__init__.py b/build/lib/opstool/preprocessing/__init__.py
index 691f530..7b1ffca 100644
--- a/build/lib/opstool/preprocessing/__init__.py
+++ b/build/lib/opstool/preprocessing/__init__.py
@@ -1,10 +1,12 @@
 from .load import gen_grav_load
 from .tcl2py import tcl2py
+from .unit_system import UnitSystem
 from .section import (Rebars, SecMesh, add_circle, add_material,
                       add_polygon, offset, var_line_string, vis_var_sec)
 
 __all__ = ["gen_grav_load",
            "tcl2py",
+           "UnitSystem",
            # -----------
            "SecMesh",
            "Rebars",
diff --git a/build/lib/opstool/preprocessing/tcl2py.py b/build/lib/opstool/preprocessing/tcl2py.py
index dd580f2..ba9a0ce 100644
--- a/build/lib/opstool/preprocessing/tcl2py.py
+++ b/build/lib/opstool/preprocessing/tcl2py.py
@@ -1,9 +1,12 @@
 import tkinter
 
+from rich import print
+
 
 def tcl2py(input_file: str,
            output_file: str,
-           prefix: str = "ops"):
+           prefix: str = "ops",
+           encoding: str = "utf-8"):
     """Convert tcl code of opensees to openseespy code.
 
     .. tip::
@@ -29,6 +32,8 @@ def tcl2py(input_file: str,
         i.e., ``import openseespy.opensees as ops``.
         If None or void str '', the prefix is not used.
         i.e., ``from openseespy.opensees import *``.
+    encoding: str, optional
+        file encoding format, by default "utf-8".
     """
     if not input_file.endswith(".tcl"):
         input_file += ".tcl"
@@ -40,18 +45,19 @@ def tcl2py(input_file: str,
     else:
         import_txt = "from openseespy.opensees import *\n\n"
         prefix = ''
-
-    with open(input_file, 'r', encoding="utf-8") as f:
+    with open(input_file, 'r', encoding=encoding) as f:
         tcl_src = f.read()
     tcl_src = tcl_src.replace("{", " { ")
     tcl_src = tcl_src.replace("}", " } ")
     interp, contents = _TclInterp(prefix)
-    interp.eval(tcl_src)
 
-    with open(output_file, mode='w', encoding="utf-8") as fw:
-        fw.write(import_txt)
-        for line in contents:
-            fw.write(line + "\n")
+    try:
+        interp.eval(tcl_src)
+    finally:
+        with open(output_file, mode='w', encoding=encoding) as fw:
+            fw.write(import_txt)
+            for line in contents:
+                fw.write(line + "\n")
 
 
 def _TclInterp(prefix):
@@ -135,8 +141,14 @@ def _beamIntegration(*args):
     def _section(*args):
         args = _remove_commit(args)
         args = tuple([_type_convert(i) for i in args])
-        if args[0] in ('NDFiber', 'Fiber'):
-            contents.append(f"{prefix}section{args[:-1]}")
+        if args[0].lower() in ('ndfiber', 'fiber'):
+            if args[0].lower() == "fiber" and ('-GJ' not in args or '-torsion' not in args):
+                print("[bold #d20962]Warning[/bold #d20962]: "
+                      "-GJ or -torsion not used for fiber section, GJ=10000 is assumed!")
+                new_args = (args[0], args[1], '-GJ', 1.E4)
+            else:
+                new_args = args[:-1]
+            contents.append(f"{prefix}section{new_args}")
             txt = args[-1]
             txt.replace("\\n", '')
             interp.eval(txt)
@@ -232,26 +244,33 @@ def _timeSeries(*args):
                 txt = f"{prefix}timeSeries('Path', {args[1]}, *{args[2:]})"
                 contents.append(txt)
             else:
-                args = tuple([_type_convert(i) for i in args])
-                contents.append(f"{prefix}timeSeries{args}")
+                contents.append(f"{prefix}timeSeries{tuple(args)}")
         else:
-            args = tuple([_type_convert(i) for i in args])
-            contents.append(f"{prefix}timeSeries{args}")
+            contents.append(f"{prefix}timeSeries{tuple(args)}")
 
     def _pattern(*args):
         args = _remove_commit(args)
         args = tuple([_type_convert(i) for i in args])
-        if args[0].lower() == "plain" and isinstance(args[2], str):
-            contents.append(f"{prefix}timeSeries('{args[2]}', {args[1]})")
-            args = list(args)
-            args[2] = args[1]
-            args = tuple(args)
-            contents.append(f"{prefix}pattern{args[:-1]}")
+        if args[0].lower() != "uniformexcitation":
+            if args[0].lower() == "plain" and isinstance(args[2], str):
+                print(
+                    f"[bold #d20962]Warning[/bold #d20962]: OpenSeesPy not support a str [bold #0099e5]{args[2]}[/bold #0099e5] "
+                    f"followed [bold #ff4c4c]plain[/bold #ff4c4c], "
+                    f"and a new [bold #f47721]timeSeries[/bold #f47721] is created with tag "
+                    f"[bold #34bf49]{args[1]}[/bold #34bf49], "
+                    f"please check this [bold #34bf49]pattern tag={args[1]}[/bold #34bf49]!")
+                contents.append(f"{prefix}timeSeries('{args[2]}', {args[1]})")
+                args = list(args)
+                args[2] = args[1]
+                args = tuple(args)
+                contents.append(f"{prefix}pattern{args[:-1]}")
+            else:
+                contents.append(f"{prefix}pattern{args[:-1]}")
+            txt = args[-1]
+            txt.replace("\\n", '')
+            interp.eval(txt)
         else:
-            contents.append(f"{prefix}pattern{args[:-1]}")
-        txt = args[-1]
-        txt.replace("\\n", '')
-        interp.eval(txt)
+            contents.append(f"{prefix}pattern{args}")
 
     def _load(*args):
         args = _remove_commit(args)
@@ -305,13 +324,47 @@ def _rayleigh(*args):
 
     def _block2D(*args):
         args = _remove_commit(args)
-        args = tuple([_type_convert(i) for i in args])
-        contents.append(f"{prefix}block2D{args}")
+        args = [_type_convert(i) for i in args]
+        txt = args[-1]
+        txt = txt.replace("\n", "").replace("\t", " ")
+        crds = txt.split()
+        crds = [_type_convert(i) for i in crds]
+        contents.append(f"crds = {crds}")
+        if isinstance(args[-2], str):
+            eleargs = args[-2].split()
+            eleargs = [_type_convert(i) for i in eleargs]
+            args = args[:-2] + eleargs
+            args = [f"'{i}'" if isinstance(i, str) else str(i)
+                    for i in args]
+            args.append("*crds")
+        else:
+            args = [f"'{i}'" if isinstance(i, str) else str(i)
+                    for i in args[:-1]]
+            args.append("*crds")
+        txt = f"{prefix}block2D(" + ", ".join(args) + ")"
+        contents.append(txt)
 
     def _block3D(*args):
         args = _remove_commit(args)
-        args = tuple([_type_convert(i) for i in args])
-        contents.append(f"{prefix}block3D{args}")
+        args = [_type_convert(i) for i in args]
+        txt = args[-1]
+        txt = txt.replace("\n", "").replace("\t", " ")
+        crds = txt.split()
+        crds = [_type_convert(i) for i in crds]
+        contents.append(f"crds = {crds}")
+        if isinstance(args[-2], str):
+            eleargs = args[-2].split()
+            eleargs = [_type_convert(i) for i in eleargs]
+            args = args[:-2] + eleargs
+            args = [f"'{i}'" if isinstance(i, str) else str(i)
+                    for i in args]
+            args.append("*crds")
+        else:
+            args = [f"'{i}'" if isinstance(i, str) else str(i)
+                    for i in args[:-1]]
+            args.append("*crds")
+        txt = f"{prefix}block3D(" + ", ".join(args) + ")"
+        contents.append(txt)
 
     def _ShallowFoundationGen(*args):
         args = _remove_commit(args)
@@ -1104,6 +1157,7 @@ def _domainCommitTag(*args):
     interp.createcommand('rigidLink', _rigidLink)
     interp.createcommand('element', _element)
     interp.createcommand('timeSeries', _timeSeries)
+    # interp.createcommand('Series', _timeSeries)
     interp.createcommand('pattern', _pattern)
     interp.createcommand('load', _load)
     interp.createcommand('eleLoad', _eleLoad)
diff --git a/build/lib/opstool/preprocessing/unit_system.py b/build/lib/opstool/preprocessing/unit_system.py
new file mode 100644
index 0000000..259cf41
--- /dev/null
+++ b/build/lib/opstool/preprocessing/unit_system.py
@@ -0,0 +1,126 @@
+import re
+import rich
+
+ratio_length = dict(inch2m=0.0254, inch2dm=0.254, inch2cm=2.54, inch2mm=25.4,
+                    inch2km=2.54e-5, inch2ft=0.0833333333,
+                    ft2mm=304.8, ft2cm=30.48, ft2dm=3.048, ft2m=0.3048, ft2km=3.048e-4,
+                    mm2cm=0.1, mm2dm=0.01, mm2m=0.001, mm2km=1e-6,
+                    cm2dm=0.1, cm2m=0.01, cm2km=1e-5, m2km=1e-3)
+ratio_force = dict(lb2lbf=1, lb2kip=0.001, lb2n=4.4482216282509,
+                   lb2kn=4.4482216282509e-3, lb2mn=4.448e-6,
+                   lb2kgf=0.45359236844386, lb2tonf=0.0004535923699994,
+                   lbf2kip=0.001, lbf2n=4.4482216282509,
+                   lbf2kn=4.4482216282509e-3, lbf2mn=4.448e-6,
+                   lbf2kgf=0.45359236844386, lbf2tonf=0.0004535923699994,
+                   kip2n=4448.2216, kip2kn=4448.2216e-3, kip2mn=4448.2216e-6,
+                   kip2kgf=453.59236844386, kip2tonf=0.4535923699994,
+                   n2kn=1e-3, n2mn=1e-6, n2kgf=0.10197162129779283,
+                   n2tonf=0.0001019716212978, kn2mn=1e-3, kn2kgf=101.9716212978,
+                   kn2tonf=0.1019716212978, mn2kgf=101971.6212978,
+                   mn2tonf=101.9716212978, kgf2tonf=0.001)
+ratio_time = dict(sec2msec=0.001)
+
+
+def ratio_update(ratio_dict):
+    temp_dict = dict()
+    for key, value in ratio_dict.items():
+        idx = key.index("2")
+        new_key = key[idx+1:] + "2" + key[:idx]
+        temp_dict[new_key] = 1 / value
+        new_key = key[:idx] + "2" + key[:idx]
+        temp_dict[new_key] = 1
+    ratio_dict.update(temp_dict)
+
+
+ratio_update(ratio_length)
+ratio_update(ratio_force)
+ratio_update(ratio_time)
+
+unit_length = ["inch", "ft", "mm", "cm", "m"]
+unit_force = ["lb", "lbf", "kip", "n", "kn", "mn", "kgf", "tonf"]
+unit_time = ["sec", "msec"]
+unit_mass = ["mg", "g", "kg", "ton", "t", "slug"]
+unit_stress = ["pa", "kpa", "mpa", "gpa", "bar", "psi", "ksi", "psf", "ksf"]
+
+
+class UnitSystem:
+    """A class for unit conversion.
+
+    Parameters
+    -----------
+    length: str, default="m"
+        Length unit base. Optional ["inch", "ft", "mm", "cm", "m"].
+    force: str, default="kN"
+        Force unit base. Optional ["lb"("lbf"), "kip", "n", "kn", "mn", "kgf", "tonf"].
+    time: str, default="sec"
+        Time unit base. Optional ["sec", "msec"].
+
+    .. note::
+        * `Mass` and `stress` units can be automatically determined based on `length` and `force` units,
+          optional mass units include ["mg", "g", "kg", "ton"("t"), "slug"],
+          and optional stress units include ["pa", "kpa", "mpa", "gpa", "bar", "psi", "ksi", "psf", "ksf"].
+
+        * You can enter any uppercase and lowercase forms, such as ``kn`` and ``kN``, ``mpa`` and ``MPa`` are equivalent.
+
+        * You can add a number after the unit to indicate a power, such as ``m3`` for ``m*m*m``.
+    """
+
+    def __init__(self,
+                 length: str = "m",
+                 force: str = "kn",
+                 time: str = "sec") -> None:
+        for unit in unit_length:
+            setattr(self, unit, ratio_length[unit + "2" + length.lower()])
+        for unit in unit_force:
+            setattr(self, unit, ratio_force[unit + "2" + force.lower()])
+        for unit in unit_time:
+            setattr(self, unit, ratio_time[unit + "2" + time.lower()])
+        # mass
+        self.kg = self.n * self.sec**2 / self.m
+        self.mg, self.g, self.ton = 1e-6 * self.kg, 1e-3 * self.kg, 1e3 * self.kg
+        self.t, self.slug = 1e3 * self.kg, 14.593902937 * self.kg
+        # stress
+        self.pa = self.n / (self.m * self.m)
+        self.kpa, self.mpa, self.gpa = 1000 * self.pa, 1e6 * self.pa, 1e9 * self.pa
+        self.bar = 1e5 * self.pa
+        self.psi, self.ksi = 6894.7572932 * self.pa, 6894757.2932 * self.pa
+        self.psf, self.ksf = 47.880208 * self.pa, 47880.2468616010 * self.pa
+
+    def __getattr__(self, item):
+        v = re.findall(r'-?\d+\.?\d*e?E?-?\d*?', item)
+        if v:
+            v = float(v[0])
+        else:
+            return getattr(self, item.lower())
+        s = ''.join([x for x in item if x.isalpha()])
+        base = getattr(self, s)
+        return base ** v
+
+    def __repr__(self):
+        txt = "\n[bold #d20962]Length unit:[/bold #d20962]\n"
+        for i, unit in enumerate(unit_length):
+            txt += f"{unit}={getattr(self, unit)}; "
+            if i > 1 and (i + 1) % 5 == 0:
+                txt += "\n"
+        txt += "\n\n[bold #f47721]Force unit:[/bold #f47721]\n"
+        for i, unit in enumerate(unit_force):
+            txt += f"{unit}={getattr(self, unit)}; "
+            if i > 1 and (i + 1) % 5 == 0:
+                txt += "\n"
+        txt += "\n\n[bold #7ac143]Time unit:[/bold #7ac143]\n"
+        for i, unit in enumerate(unit_time):
+            txt += f"{unit}={getattr(self, unit)}; "
+            if i > 1 and (i + 1) % 5 == 0:
+                txt += "\n"
+        txt += "\n\n[bold #00bce4]Mass unit:[/bold #00bce4]\n"
+        for i, unit in enumerate(unit_mass):
+            txt += f"{unit}={getattr(self, unit)}; "
+            if i > 1 and (i + 1) % 5 == 0:
+                txt += "\n"
+        txt += "\n\n[bold #7d3f98]Pressure unit:[/bold #7d3f98]\n"
+        for i, unit in enumerate(unit_stress):
+            txt += f"{unit}={getattr(self, unit)}; "
+            if i > 1 and (i + 1) % 5 == 0:
+                txt += "\n"
+        rich.print(txt)
+        return ""
diff --git a/build/lib/opstool/vis/_plotly_base.py b/build/lib/opstool/vis/_plotly_base.py
index 13cc0a5..c7164ea 100644
--- a/build/lib/opstool/vis/_plotly_base.py
+++ b/build/lib/opstool/vis/_plotly_base.py
@@ -122,6 +122,7 @@ def _model_vis(
         show_ele_label: bool = False,
         show_local_crd: bool = False,
         show_fix_node: bool = True,
+        show_constrain_dof: bool = False,
         label_size: float = 8,
         show_outline: bool = True,
         opacity: float = 1.0,
@@ -359,7 +360,7 @@ def _model_vis(
                 hovertemplate='<b>z</b>')
             plotter.extend([plotter1, plotter2, plotter3])
     # mp constraint lines
-    plotter = _show_mp_constraint(obj, plotter, model_info)
+    _show_mp_constraint(obj, plotter, model_info, show_constrain_dof)
 
     fig.add_traces(plotter)
 
@@ -397,7 +398,7 @@ def _model_vis(
         fig.show()
 
 
-def _show_mp_constraint(obj, plotter, model_info):
+def _show_mp_constraint(obj, plotter, model_info, show_dofs):
     points = model_info["ConstrainedCoords"]
     cells = model_info["ConstrainedCells"]
     cells = _reshape_cell(cells)
@@ -412,13 +413,13 @@ def _show_mp_constraint(obj, plotter, model_info):
                                         width=obj.line_width / 3),
                                     mode="lines", name="mp constraint",
                                     connectgaps=False, hoverinfo="skip"))
-        x, y, z = [line_mid_points[:, j] for j in range(3)]
-        txt_plot = go.Scatter3d(x=x, y=y, z=z, text=dofs,
-                                textfont=dict(color=obj.color_constraint,
-                                              size=12),
-                                mode="text", name="constraint dofs")
-        plotter.append(txt_plot)
-    return plotter
+        if show_dofs:
+            x, y, z = [line_mid_points[:, j] for j in range(3)]
+            txt_plot = go.Scatter3d(x=x, y=y, z=z, text=dofs,
+                                    textfont=dict(color=obj.color_constraint,
+                                                  size=12),
+                                    mode="text", name="constraint dofs")
+            plotter.append(txt_plot)
 
 
 def _eigen_vis(
diff --git a/build/lib/opstool/vis/_pyvista_base.py b/build/lib/opstool/vis/_pyvista_base.py
index 3018756..b4b405d 100644
--- a/build/lib/opstool/vis/_pyvista_base.py
+++ b/build/lib/opstool/vis/_pyvista_base.py
@@ -13,6 +13,7 @@ def _model_vis(
         show_ele_label: bool = False,
         show_local_crd: bool = False,
         show_fix_node: bool = True,
+        show_constrain_dof: bool = False,
         label_size: float = 8,
         show_outline: bool = True,
         opacity: float = 1.0,
@@ -30,7 +31,7 @@ def _model_vis(
             cells[name] = grp2[name][...]
 
     plotter = pv.Plotter(notebook=obj.notebook)
-    plotter = _plot_model(obj, plotter, model_info, cells, opacity)
+    _plot_model(obj, plotter, model_info, cells, opacity)
 
     txt = f"OpenSees 3D View\nNum. of Node:{model_info['num_node']}\nNum. of Ele:{model_info['num_ele']}"
     plotter.add_text(txt, position="upper_right", font_size=10, font="courier")
@@ -52,13 +53,13 @@ def _model_vis(
                                  font_size=label_size, bold=False, always_visible=True)
     # local axes
     if show_local_crd:
-        plotter = _show_beam_local_axes(plotter, model_info)
-        plotter = _show_link_local_axes(plotter, model_info)
+        _show_beam_local_axes(plotter, model_info)
+        _show_link_local_axes(plotter, model_info)
     # fix nodes
     if show_fix_node:
-        plotter = _show_fix_node(plotter, model_info)
+        _show_fix_node(plotter, model_info)
     # mp constraint lines
-    plotter = _show_mp_constraint(obj, plotter, model_info)
+    _show_mp_constraint(obj, plotter, model_info, show_constrain_dof)
     plotter.add_axes()
     plotter.view_isometric()
     if np.max(model_info["model_dims"]) <= 2:
@@ -69,7 +70,7 @@ def _model_vis(
     plotter.close()
 
 
-def _show_mp_constraint(obj, plotter, model_info):
+def _show_mp_constraint(obj, plotter, model_info, show_dofs):
     points = model_info["ConstrainedCoords"]
     cells = model_info["ConstrainedCells"]
     midcoords = model_info["ConstrainedMidCoords"]
@@ -79,10 +80,10 @@ def _show_mp_constraint(obj, plotter, model_info):
         mesh = _generate_mesh(points, cells, kind="line")
         plotter.add_mesh(mesh, color=obj.color_constraint,
                          render_lines_as_tubes=False, line_width=obj.line_width / 3)
-        plotter.add_point_labels(midcoords, dofs, text_color=obj.color_constraint,
-                                 font_size=12, bold=True, show_points=False,
-                                 always_visible=True, shape_opacity=0)
-    return plotter
+        if show_dofs:
+            plotter.add_point_labels(midcoords, dofs, text_color=obj.color_constraint,
+                                     font_size=12, bold=True, show_points=False,
+                                     always_visible=True, shape_opacity=0)
 
 
 def _show_beam_local_axes(plotter, model_info):
@@ -131,7 +132,6 @@ def _show_beam_local_axes(plotter, model_info):
         )
     else:
         warnings.warn("Model has no frame elements when show_local_crd=True!")
-    return plotter
 
 
 def _show_link_local_axes(plotter, model_info):
@@ -181,7 +181,6 @@ def _show_link_local_axes(plotter, model_info):
     else:
         # warnings.warn("Model has no link elements!")
         pass
-    return plotter
 
 
 def _show_fix_node(plotter, model_info):
@@ -219,7 +218,6 @@ def _show_fix_node(plotter, model_info):
                          render_lines_as_tubes=False, line_width=2)
     else:
         warnings.warn("Model has no fix nodes!")
-    return plotter
 
 
 def _eigen_vis(
@@ -1294,4 +1292,3 @@ def _plot_model(obj, plotter, model_info, cells, opacity):
         plotter.add_mesh(
             bri_plot, color=obj.color_solid, show_edges=True, opacity=opacity
         )
-    return plotter
diff --git a/build/lib/opstool/vis/ops_vis_plotly.py b/build/lib/opstool/vis/ops_vis_plotly.py
index 8d48a1d..eeaa612 100644
--- a/build/lib/opstool/vis/ops_vis_plotly.py
+++ b/build/lib/opstool/vis/ops_vis_plotly.py
@@ -90,6 +90,7 @@ def model_vis(
         show_ele_label: bool = False,
         show_local_crd: bool = False,
         show_fix_node: bool = True,
+        show_constrain_dof: bool = False,
         label_size: float = 8,
         show_outline: bool = True,
         opacity: float = 1.0,
@@ -116,6 +117,8 @@ def model_vis(
             Whether to display the local axes of beam and link elements.
         show_fix_node: bool, default=True
             Whether to display the fix nodes.
+        show_constrain_dof: bool, default=False
+            Whether to display labels for constrained degrees of freedom.
         label_size: float, default=8
             The foontsize of node and ele label.
         show_outline: bool, default=True
@@ -136,6 +139,7 @@ def model_vis(
                    show_ele_label=show_ele_label,
                    show_local_crd=show_local_crd,
                    show_fix_node=show_fix_node,
+                   show_constrain_dof=show_constrain_dof,
                    label_size=label_size,
                    show_outline=show_outline,
                    opacity=opacity,
diff --git a/build/lib/opstool/vis/ops_vis_pyvista.py b/build/lib/opstool/vis/ops_vis_pyvista.py
index f84d5f5..5e475fc 100644
--- a/build/lib/opstool/vis/ops_vis_pyvista.py
+++ b/build/lib/opstool/vis/ops_vis_pyvista.py
@@ -89,10 +89,11 @@ def model_vis(
         show_ele_label: bool = False,
         show_local_crd: bool = False,
         show_fix_node: bool = True,
+        show_constrain_dof: bool = False,
         label_size: float = 8,
         show_outline: bool = True,
         opacity: float = 1.0,
-        save_fig: str = 'ModelVis.svg'
+        save_fig: str = None
     ):
         """
         Visualize the model in the current domain.
@@ -115,6 +116,8 @@ def model_vis(
             Whether to display the local axes of beam and link elements.
         show_fix_node: bool, default=True
             Whether to display the fix nodes.
+        show_constrain_dof: bool, default=False
+            Whether to display labels for constrained degrees of freedom.
         label_size: float, default=8
             The foontsize of node and ele label.
         show_outline: bool, default=True
@@ -142,6 +145,7 @@ def model_vis(
                    show_ele_label=show_ele_label,
                    show_local_crd=show_local_crd,
                    show_fix_node=show_fix_node,
+                   show_constrain_dof=show_constrain_dof,
                    label_size=label_size,
                    show_outline=show_outline,
                    opacity=opacity,
diff --git a/dist/opstool-0.6.0-py3-none-any.whl b/dist/opstool-0.6.0-py3-none-any.whl
new file mode 100644
index 0000000..a080ce7
Binary files /dev/null and b/dist/opstool-0.6.0-py3-none-any.whl differ
diff --git a/dist/opstool-0.6.0.tar.gz b/dist/opstool-0.6.0.tar.gz
new file mode 100644
index 0000000..d7da1f5
Binary files /dev/null and b/dist/opstool-0.6.0.tar.gz differ
diff --git a/dist/opstool-0.5.0-py3-none-any.whl b/dist_old/opstool-0.5.0-py3-none-any.whl
similarity index 100%
rename from dist/opstool-0.5.0-py3-none-any.whl
rename to dist_old/opstool-0.5.0-py3-none-any.whl
diff --git a/dist/opstool-0.5.0.tar.gz b/dist_old/opstool-0.5.0.tar.gz
similarity index 100%
rename from dist/opstool-0.5.0.tar.gz
rename to dist_old/opstool-0.5.0.tar.gz
diff --git a/doc/source/CHANGELOG.rst b/doc/source/CHANGELOG.rst
index 2e5926e..0aa99c6 100644
--- a/doc/source/CHANGELOG.rst
+++ b/doc/source/CHANGELOG.rst
@@ -1,6 +1,12 @@
 Changelog
 =============
 
+v0.6.0
+-------
+- Added the unit conversion class :func:`opstool.preprocessing.UnitSystem`.
+- Fixed bugs in :func:`opstool.preprocessing.tcl2py`.
+- Added the arg `show_constrain_dof` in :meth:`opstool.vis.OpsVisPyvista.model_vis` and :meth:`opstool.vis.OpsVisPlotly.model_vis`.
+
 v0.5.0
 -------
 - Added the function :func:`~opstool.vis.save_tikz` to save as the ``.tex`` file using `tikz` package, which can be visualized by native ``texlive`` or web-based ``overleaf``.
@@ -8,7 +14,7 @@ v0.5.0
 
 v0.4.2
 -------
-- Fixed som bugs in ``tclpy()``.
+- Fixed som bugs in :func:`opstool.preprocessing.tcl2py`.
 - Updated the version requirements for mac.
 
 v0.4.1
diff --git a/src/opstool.egg-info/PKG-INFO b/src/opstool.egg-info/PKG-INFO
index 6053cfa..85a67b1 100644
--- a/src/opstool.egg-info/PKG-INFO
+++ b/src/opstool.egg-info/PKG-INFO
@@ -1,6 +1,6 @@
 Metadata-Version: 2.1
 Name: opstool
-Version: 0.5.0
+Version: 0.6.0
 Summary: openseespy toolbox
 Home-page: https://github.com/yexiang1992
 Author: Yexiang Yan
diff --git a/src/opstool.egg-info/SOURCES.txt b/src/opstool.egg-info/SOURCES.txt
index 461535d..899bb4b 100644
--- a/src/opstool.egg-info/SOURCES.txt
+++ b/src/opstool.egg-info/SOURCES.txt
@@ -26,6 +26,7 @@ src/opstool/examples/__init__.py
 src/opstool/preprocessing/__init__.py
 src/opstool/preprocessing/load.py
 src/opstool/preprocessing/tcl2py.py
+src/opstool/preprocessing/unit_system.py
 src/opstool/preprocessing/section/__init__.py
 src/opstool/preprocessing/section/lib_sec_mesh.py
 src/opstool/preprocessing/section/sec_mesh.py
diff --git a/src/opstool/__about__.py b/src/opstool/__about__.py
index 3d18726..906d362 100644
--- a/src/opstool/__about__.py
+++ b/src/opstool/__about__.py
@@ -1 +1 @@
-__version__ = "0.5.0"
+__version__ = "0.6.0"
diff --git a/src/opstool/__pycache__/__about__.cpython-39.pyc b/src/opstool/__pycache__/__about__.cpython-39.pyc
index 71cf23a..cb138e9 100644
Binary files a/src/opstool/__pycache__/__about__.cpython-39.pyc and b/src/opstool/__pycache__/__about__.cpython-39.pyc differ