#LyX 1.4.1 created this file. For more info see http://www.lyx.org/
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\begin_document
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\textclass book
\language english
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\end_header
\begin_body
\begin_layout Chapter
Preparing a model for reuse
\begin_inset LatexCommand \index{reuse}
\end_inset
\begin_inset LatexCommand \label{cha:model2}
\end_inset
\end_layout
\begin_layout Standard
There are four major ways to prepare a model for reuse.
First, you should add comments to a model.
Second, you should add methods to a model definition to pass to a future
user your experience in creating an instance of this type which is well-posed.
Third, you should parameterize the model type definition to alert a future
user as to which parts of this model you deem to be the most likely to
be shared.
And fourth, you should prepare a script that a future user can run to solve
a sample problem involving an instance of the model.
We shall consider each of these items in turn in what follows.
\end_layout
\begin_layout Section
Adding comments
\begin_inset LatexCommand \index{comments}
\end_inset
and notes
\begin_inset LatexCommand \index{notes}
\end_inset
\end_layout
\begin_layout Standard
In ASCEND we can create traditional comments for a model -- i.e., add text
to the code that aids anyone looking at the code to understand what is
there.
We do this by enclosing text with the delimiters
\family typewriter
(*
\family default
\begin_inset LatexCommand \index{(*}
\end_inset
and
\family typewriter
*)
\family default
\begin_inset LatexCommand \index{*)}
\end_inset
.
Thus the line
\end_layout
\begin_layout LyX-Code
(* This is a comment *)
\end_layout
\begin_layout Standard
is a comment in ASCEND.
Traditional comments are only visible when we display the code using the
Display code tool
\begin_inset LatexCommand \index{Display code tool}
\end_inset
\begin_inset LatexCommand \index{tool, Display code}
\end_inset
in the Library window or when we view the code in the text editor we used
to create it.
\end_layout
\begin_layout Standard
We suggest we can do more for the modeler with the concept of Notes, a form
of "active" comments available in ASCEND.
ASCEND has tools to extract notes and display them in searchable form.
\end_layout
\begin_layout Standard
\begin_inset Marginal
status collapsed
\begin_layout Standard
notes are active comments
\begin_inset LatexCommand \index{comments, active}
\end_inset
\end_layout
\end_inset
In Figure
\begin_inset LatexCommand \ref{fig:model2.vesselWithNotes}
\end_inset
\noun off
we show two types of notes the modeler can add.
Longer notes are set off in block style starting with the keyword
\family typewriter
\noun default
NOTES
\family default
\noun off
and ending with
\family typewriter
\noun default
END NOTES
\family default
\noun off
.
In this model, we declare two notes in this manner: (1) to indicate who
the author is and (2) to indicate the creation date for this model.
Note that the notes are director to documenting SELF, which is the model
itself -- i.e., the vessel model as a whole object.
The object one documents can be any instance in the model -- any variable,
equation or part.
The tools for handling notes can sort on the terms enclosed in single quotes
so one could, for example, isolate the author notes for all the models.
\end_layout
\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open
\begin_layout LyX-Code
REQUIRE "atoms.a4l";
\end_layout
\begin_layout LyX-Code
MODEL vessel;
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'author'SELF {Arthur W.
Westerberg}
\end_layout
\begin_layout LyX-Code
'creation date' SELF {May, 1998}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
(* variables *)
\end_layout
\begin_layout LyX-Code
side_area "the area of the cylindrical side wall of the vessel",
\end_layout
\begin_layout LyX-Code
end_area "the area of the flat ends of the vessel"
\end_layout
\begin_layout LyX-Code
IS_A area;
\end_layout
\begin_layout LyX-Code
vessel_vol "the volume contained within the cylindrical vessel",
\end_layout
\begin_layout LyX-Code
wall_vol "the volume of the walls for the vessel"
\end_layout
\begin_layout LyX-Code
IS_A volume;
\end_layout
\begin_layout LyX-Code
wall_thickness "the thickness of all of the vessel walls",
\end_layout
\begin_layout LyX-Code
H "the vessel height (of the cylindrical side walls)",
\end_layout
\begin_layout LyX-Code
D "the vessel diameter"
\end_layout
\begin_layout LyX-Code
IS_A distance;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio "the ratio of vessel height to diameter"
\end_layout
\begin_layout LyX-Code
IS_A factor;
\end_layout
\begin_layout LyX-Code
metal_density "density of the metal from which the vessel
\end_layout
\begin_layout LyX-Code
is constructed"
\end_layout
\begin_layout LyX-Code
IS_A mass_density;
\end_layout
\begin_layout LyX-Code
metal_mass "the mass of the metal in the walls of the vessel"
\end_layout
\begin_layout LyX-Code
IS_A mass;
\end_layout
\begin_layout LyX-Code
(* equations *)
\end_layout
\begin_layout LyX-Code
FlatEnds:end_area = 1{PI} * D^2 / 4;
\end_layout
\begin_layout LyX-Code
Sides:side_area = 1{PI} * D * H;
\end_layout
\begin_layout LyX-Code
Cylinder:vessel_vol = end_area * H;
\end_layout
\begin_layout LyX-Code
Metal_volume:(side_area + 2 * end_area) * wall_thickness = wall_vol;
\end_layout
\begin_layout LyX-Code
HD_definition:D * H_to_D_ratio = H;
\end_layout
\begin_layout LyX-Code
VesselMass:metal_mass = metal_density * wall_vol;
\end_layout
\begin_layout LyX-Code
END vessel;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
ADD NOTES IN vessel;
\end_layout
\begin_layout LyX-Code
'description' SELF {This model relates the dimensions of a
\end_layout
\begin_layout LyX-Code
cylindrical vessel -- e.g., diameter,
\end_layout
\begin_layout LyX-Code
height and wall thicknes to the volume of metal
\end_layout
\begin_layout LyX-Code
in the walls.
It uses a thin wall assumption
\end_layout
\begin_layout LyX-Code
-- i.e., that the volume of metal is the area of
\end_layout
\begin_layout LyX-Code
the vessel times the wall thickness.}
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to illustrate the insertion of notes into a model}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout Caption
Vessel model with Notes added (model vesselNotes.a4c
\begin_inset LatexCommand \index{vesselNotes.a4c}
\end_inset
)
\begin_inset LatexCommand \label{fig:model2.vesselWithNotes}
\end_inset
\end_layout
\end_inset
\end_layout
\begin_layout Standard
A user may use any term desired in the single quotes.
We have not decided yet what the better set of terms should be so we do
not as yet suggest any.
With time we expect the terms used to settle down to just a few that are
repeated for all the models in a library.
\end_layout
\begin_layout Standard
\begin_inset Marginal
status collapsed
\begin_layout Standard
there are short notes, long notes and separate notes
\end_layout
\end_inset
There are also short notes we can attach to every variable in the model.
A "one liner
\begin_inset LatexCommand \index{notes, one liner}
\end_inset
\begin_inset LatexCommand \index{one liner}
\end_inset
" in double quotes just following the variable name allows the automatic
annotation of variables in reports.
\end_layout
\begin_layout Standard
The last few lines of Figure
\begin_inset LatexCommand \ref{fig:model2.vesselWithNotes}
\end_inset
\noun off
shows adding notes we write in a separate ADD NOTES IN object
\begin_inset LatexCommand \index{ADD NOTES IN object}
\end_inset
.
This object can appear before or after or in a different file from the
object it describes.
This style of note writing is useful as it allows another person to add
notes to a model without changing the code for a model.
Thus it allows several different sets of notes to exist for a single model,
with the choice of which to use being up to the person maintaining the
model library.
Finally, it allows one to eliminate the "clutter" the documentation often
adds to the code.
\end_layout
\begin_layout Section
Adding methods
\begin_inset LatexCommand \index{methods, adding}
\end_inset
\begin_inset LatexCommand \index{adding methods}
\end_inset
\end_layout
\begin_layout Standard
We would next like to pass along our experiences in getting this model to
be well-posed -- i.e., we would like to tell future users which variables
we decided to fix and which we decided to calculate.
We would also like to provide some typical values for the variables we
decided to fix.
ASCEND allows us to attach any number of methods to a type definition.
Methods are procedural code that we can request be run through the interface
while browsing a model instance.
We shall include methods as described in Table
\begin_inset LatexCommand \ref{tab:model2.reqdMethods}
\end_inset
\noun off
to set just the right fixed flags and variable values for an instance of
our vessel model to be well-posed.
\end_layout
\begin_layout Standard
The system has defaults definitions for all these methods.
You already saw that to be true if you went through the process of setting
all the fixed flags to FALSE in the previous chapter.
In case you did not, load and compile the vesselPlain.a4c model in ASCEND.
Export the compiled instance to the Browser.
Then in the Browser, under the Edit button, select Run method.
You will see a list containing these and other methods we shall be describing
shortly.
Select specify and hit the OK button.
Then look in the Console window.
A message similar to the following will appear, with all but the first
line being in red to signify you should pay attention to the message:
\end_layout
\begin_layout LyX-Code
Running method specify in v
\end_layout
\begin_layout LyX-Code
Found STOP
\begin_inset LatexCommand \index{STOP}
\end_inset
statement in METHOD
\end_layout
\begin_layout LyX-Code
C:
\backslash
PROGRAM FILES
\backslash
ASCEND
\backslash
ASCEND4
\backslash
models
\backslash
basemodel.a4l:307
\end_layout
\begin_layout LyX-Code
STOP {Error
\begin_inset LatexCommand \index{error}
\end_inset
! Standard method "specify" called but not
\end_layout
\begin_layout LyX-Code
written in MODEL.};
\end_layout
\begin_layout Standard
This message is telling you that you have just run the default specify method
\begin_inset LatexCommand \index{specify method, default}
\end_inset
.
We have to hand-craft every specify method so the default method is not
appropriate.
This message is alerting us to the fact that we did not yet write a special
specify method for this model type.
\end_layout
\begin_layout Standard
Try running the ClearAll
\begin_inset LatexCommand \index{ClearAll}
\end_inset
method.
The default ClearAll method is always the one you will want so it does
not put out a message to alert you that it is the default.
\end_layout
\begin_layout Standard
\begin_inset Float table
wide false
sideways false
status open
\begin_layout Caption
\begin_inset LatexCommand \label{tab:model2.reqdMethods}
\end_inset
Some of the methods
\begin_inset LatexCommand \index{methods, required}
\end_inset
we require for putting a model into an ASCEND library
\end_layout
\begin_layout Standard
\begin_inset Tabular
|
\begin_inset Text
\begin_layout Standard
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
\end_layout
\end_inset
|
|
\begin_inset Text
\begin_layout Standard
\family typewriter
ClearAll
\family default
\begin_inset LatexCommand \index{ClearAll}
\end_inset
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
a method to set all the .fixed flags for variables in the type to FALSE.
This puts these flags into a known standard state -- i.e., all are FALSE.
All models inherit this method from the base model and the need to rewrite
it is very, very rare.
\end_layout
\end_inset
|
|
\begin_inset Text
\begin_layout Standard
\family typewriter
specify
\family default
\begin_inset LatexCommand \index{specify}
\end_inset
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
a method which assumes all the fixed flags are currently FALSE and which
then sets a suitable set of fixed flags to TRUE to make an instance of
this type of model well-posed.
A well-posed model is one that is square (n equations in n unknowns) and
solvable.
\end_layout
\end_inset
|
|
\begin_inset Text
\begin_layout Standard
\family typewriter
reset
\family default
\begin_inset LatexCommand \index{reset}
\end_inset
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
a method which first runs the ClearAll method and then the specify method.
We include this method because it is very convenient.
We only have to run one method to make any simulation well-posed, no matter
how its fixed flags are currently set.
All models inherit this method from the base model, as with ClearAll .
It should only rarely have to be rewritten for a model.
\end_layout
\end_inset
|
|
\begin_inset Text
\begin_layout Standard
\family typewriter
values
\family default
\begin_inset LatexCommand \index{values}
\end_inset
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
a method to establish typical values for the variables we have fixed in
an application or test model.
We may also supply values for some of the variables we will be computing
to aid in solving a model instance of this type.
These values reflectiveness that we have tested for a simulation of this
type and found to work.
\end_layout
\end_inset
|
\end_inset
\end_layout
\end_inset
\end_layout
\begin_layout Standard
\begin_inset Marginal
status collapsed
\begin_layout Standard
writing the specify and values methods
\end_layout
\end_inset
To write the
\family typewriter
specify
\family default
and
\family typewriter
values
\family default
methods for our vessel model, we note that we have successfully solved
the vessel model in at least two different ways above.
Thus both variations are examples of being âwell-posed.â We can choose which
variation we shall use when creating the
\family typewriter
specify
\family default
method for our vessel type definition.
Let us choose the alternative where we fixed
\family typewriter
vessel_volume
\family default
,
\family typewriter
H_to_D_ratio
\family default
,
\family typewriter
metal_density
\family default
and
\family typewriter
wall_thickness
\family default
and provided them with the values of 250 ft^3, 3, 5000 kg/m^3 and 5 mm
respectively to be our âstandardâ specification.
Default methods
\family typewriter
ClearAll
\family default
and
\family typewriter
reset
\family default
are appropriate
\end_layout
\begin_layout Standard
\begin_inset Marginal
status collapsed
\begin_layout Standard
default methods ClearAll and reset are appropriate
\end_layout
\end_inset
As already noted, the purpose of
\family typewriter
ClearAll
\family default
is to set all the fixed flags to FALSE, a well-defined state from which
we can start over to set these flags as we wish them set.
\family typewriter
reset
\family default
simply runs
\family typewriter
ClearAll
\family default
and then
\family typewriter
specify
\family default
for a model.
The default versions for these two methods are generally exactly what one
wants so one need not write these.
\end_layout
\begin_layout Standard
Figure
\begin_inset LatexCommand \ref{fig:model2.vesselWithMethods}
\end_inset
\noun off
illustrates our vessel model with our local versions added for
\family typewriter
\noun default
specify
\family default
\noun off
and
\family typewriter
\noun default
values
\family default
\noun off
.
Look only at these for the moment and note that they do what we described
above.
We show some other methods we shall explain in a moment.
\end_layout
\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open
\begin_layout LyX-Code
REQUIRE "atoms.a4l";
\end_layout
\begin_layout LyX-Code
MODEL vessel;
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'author' SELF {Arthur W.
Westerberg}
\end_layout
\begin_layout LyX-Code
'creation date' SELF {May, 1998}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
(* variables *)
\end_layout
\begin_layout LyX-Code
side_area "the area of the cylindrical side wall of the vessel",
\end_layout
\begin_layout LyX-Code
end_area "the area of the flat ends of the vessel"
\end_layout
\begin_layout LyX-Code
IS_A area;
\end_layout
\begin_layout LyX-Code
vessel_vol "the volume contained within the cylindrical vessel",
\end_layout
\begin_layout LyX-Code
wall_vol "the volume of the walls for the vessel"
\end_layout
\begin_layout LyX-Code
IS_A volume;
\end_layout
\begin_layout LyX-Code
wall_thickness "the thickness of all of the vessel walls",
\end_layout
\begin_layout LyX-Code
H "the vessel height (of the cylindrical side walls)",
\end_layout
\begin_layout LyX-Code
D "the vessel diameter"
\end_layout
\begin_layout LyX-Code
IS_A distance;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio "the ratio of vessel height to diameter"
\end_layout
\begin_layout LyX-Code
IS_A factor;
\end_layout
\begin_layout LyX-Code
metal_density "density of the metal from which the vessel
\end_layout
\begin_layout LyX-Code
is constructed"
\end_layout
\begin_layout LyX-Code
IS_A mass_density;
\end_layout
\begin_layout LyX-Code
metal_mass "the mass of the metal in the walls of the vessel"
\end_layout
\begin_layout LyX-Code
IS_A mass;
\end_layout
\begin_layout LyX-Code
(* equations *)
\end_layout
\begin_layout LyX-Code
FlatEnds:end_area = 1{PI} * D^2 / 4;
\end_layout
\begin_layout LyX-Code
Sides:side_area = 1{PI} * D * H;
\end_layout
\begin_layout LyX-Code
Cylinder:vessel_vol = end_area * H;
\end_layout
\begin_layout LyX-Code
Metal_volume:(side_area + 2 * end_area) * wall_thickness = wall_vol;
\end_layout
\begin_layout LyX-Code
HD_definition:D * H_to_D_ratio = H;
\end_layout
\begin_layout LyX-Code
VesselMass:metal_mass = metal_density * wall_vol;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
METHODS
\end_layout
\begin_layout LyX-Code
METHOD specify;
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to fix four variables and make the problem well-posed}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
vessel_vol.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
wall_thickness.fixed :=TRUE;
\end_layout
\begin_layout LyX-Code
metal_density.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
END specify;
\end_layout
\begin_layout LyX-Code
METHOD values;
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to set the values for the fixed variables}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio := 2;
\end_layout
\begin_layout LyX-Code
vessel_vol := 250 {ft^3};
\end_layout
\begin_layout LyX-Code
wall_thickness := 5 {mm};
\end_layout
\begin_layout LyX-Code
metal_density := 5000 {kg/m^3};
\end_layout
\begin_layout LyX-Code
END values;
\end_layout
\begin_layout LyX-Code
METHOD bound_self;
\end_layout
\begin_layout LyX-Code
END bound_self;
\end_layout
\begin_layout LyX-Code
METHOD scale_self;
\end_layout
\begin_layout LyX-Code
END scale_self;
\end_layout
\begin_layout LyX-Code
METHOD default_self;
\end_layout
\begin_layout LyX-Code
D:=1 {m};
\end_layout
\begin_layout LyX-Code
H:=1 {m};
\end_layout
\begin_layout LyX-Code
H_to_D_ratio :=1;
\end_layout
\begin_layout LyX-Code
vessel_vol := 1 {m^3};
\end_layout
\begin_layout LyX-Code
wall_thickness :=5 {mm};
\end_layout
\begin_layout LyX-Code
metal_density :=5000 {kg/m^3};
\end_layout
\begin_layout LyX-Code
END default_self;
\end_layout
\begin_layout LyX-Code
END vessel;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
ADD NOTES IN vessel;
\end_layout
\begin_layout LyX-Code
'description' SELF {This model relates the dimensions of a
\end_layout
\begin_layout LyX-Code
cylindrical vessel -- e.g., diameter, height and wall thickness
\end_layout
\begin_layout LyX-Code
to the volume of metal in the walls.
It uses a thin wall
\end_layout
\begin_layout LyX-Code
assumption -- i.e., that the volume of metal is the area of
\end_layout
\begin_layout LyX-Code
the vessel times the wall thickness.}
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to illustrate the insertion of notes into a model}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout Caption
Version of vessel with methods added (vesselMethods.a4c
\begin_inset LatexCommand \index{vesselMethods.a4c}
\end_inset
)
\begin_inset LatexCommand \label{fig:model2.vesselWithMethods}
\end_inset
\end_layout
\end_inset
\end_layout
\begin_layout Standard
In Table
\begin_inset LatexCommand \ref{tab:model2.addedReqdMethods}
\end_inset
\noun off
we describe additional methods we require before we will put a model into
one of our libraries.
Each of these had two versions, both of which we require.
The designation _self
\begin_inset LatexCommand \index{\_self}
\end_inset
is for a method to do something for all the variables and/or parts we have
defined locally within the current model with an IS_A statement.
The designation _all
\begin_inset LatexCommand \index{\_all}
\end_inset
is for a method to do something for parts that are defined within an "outer"
model that has an instance of this model as a part.
The "outer" model is at a higher scope
\begin_inset LatexCommand \index{scope}
\end_inset
.
It can share its parts with this model by passing them in as parameters,
a topic we cover shortly in
\noun default
Section
\noun off
\begin_inset LatexCommand \ref{sec:model2.parameterizingVessel}
\end_inset
.
\noun default
\noun off
Only the _self versions of these methods are relevant here and are in
\noun default
Figure
\noun off
\begin_inset LatexCommand \ref{fig:model2.vesselWithMethods}
\end_inset
.
\end_layout
\begin_layout Standard
\begin_inset Float table
wide false
sideways false
status open
\begin_layout Caption
Additional methods
\begin_inset LatexCommand \index{methods. required}
\end_inset
required for model in ASCEND libraries
\begin_inset LatexCommand \label{tab:model2.addedReqdMethods}
\end_inset
\end_layout
\begin_layout Standard
\begin_inset Tabular
|
\begin_inset Text
\begin_layout Standard
method
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
description
\end_layout
\end_inset
|
|
\begin_inset Text
\begin_layout Standard
\family typewriter
default_self
\begin_inset LatexCommand \index{default\_self}
\end_inset
, default_all
\family default
\begin_inset LatexCommand \index{default\_all}
\end_inset
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
a method called automatically when any simulation is compiled to provide
default values and adjust bounds for any variables which may have unsuitable
defaults in their ATOM definitions.
Usually the variables selected are those for which the model becomes ill-behave
d if given poor initial guesses or bounds (e.g., zero).
\end_layout
\end_inset
|
|
\begin_inset Text
\begin_layout Standard
\family typewriter
bound_self
\begin_inset LatexCommand \index{bound\_self}
\end_inset
, bound_all
\family default
\begin_inset LatexCommand \index{bound\_all}
\end_inset
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
a method to update the .
upper_bound and .
lower_bound value for each of the variables.
ASCEND solvers use these bound values to help solve the model equations.
\end_layout
\end_inset
|
|
\begin_inset Text
\begin_layout Standard
\family typewriter
scale_self
\begin_inset LatexCommand \index{scale\_self}
\end_inset
, scale_all
\family default
\begin_inset LatexCommand \index{scale\_all}
\end_inset
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
a method to update the .
nominal value for each of the variables.
ASCEND solvers will use these nominal values to rescale the variable to
have a value of about one in magnitude to help solve the model equations.
\end_layout
\end_inset
|
|
\begin_inset Text
\begin_layout Standard
\family typewriter
check_self
\begin_inset LatexCommand \index{check\_self}
\end_inset
, check_all
\family default
\begin_inset LatexCommand \index{check\_all}
\end_inset
\end_layout
\end_inset
|
\begin_inset Text
\begin_layout Standard
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
a method to check that the computations make sense.
At first this method may be empty, but, with experience, one can add statements
that detect answers that appear to be wrong.
As ASCEND already does bounds checking, one should not check for going
past bounds here.
However, there could be a rule of thumb available that suggests one computed
variable should be about an order of magnitude larger than another.
This check could be done in this method.
\end_layout
\end_inset
|
\end_inset
\end_layout
\end_inset
\end_layout
\begin_layout Standard
\begin_inset Marginal
status collapsed
\begin_layout Standard
standard methods to a model definition
\end_layout
\end_inset
The
\family typewriter
bound_self
\family default
and
\family typewriter
scale_self
\family default
, methods we have written are both empty.
We anticipate no difficulties with variable scaling or bounding for this
small model.
Larger models can often give difficult problems in solving if the variables
in them are not properly scaled and bounded; these issues must be taken
very seriously for such models.
\end_layout
\begin_layout Standard
We have included the variables that define the geometry of the vessel in
\family typewriter
defaults_self
\family default
method to avoid such things as negative initial values for vessel_volume.
The compiler for ASCEND runs this method as soon as the model is compiled
into an instance so the variables mentioned here start with their default
values.
\end_layout
\begin_layout Standard
\begin_inset Marginal
status open
\begin_layout Standard
using methods when solving
\end_layout
\end_inset
Exit ASCEND and repeat all the steps above to edit, load and compile this
new vessel type definition.
Then proceed as follows.
\end_layout
\begin_layout Itemize
In the Browser window, examine the values for those variables mentioned
in the default_self method.
Note they already have their default values.
\end_layout
\begin_layout Itemize
To place the new instance v in a solvable state, go to the Browser window.
Pick the command Run method under the Edit button.
Select first the method values and hit OK.
\end_layout
\begin_layout Itemize
Repeat the last step but this time select the method reset.
\end_layout
\begin_layout Standard
In the Browser, examine the values for the variables listed in the method
values in Figure
\begin_inset LatexCommand \ref{fig:model2.vesselWithMethods}
\end_inset
\noun off
.
They should be set to those stated (remember you can alter the units ASCEND
uses to report the values by using the tools in the Units window).Also examine
the fixed flags for these variables; they should all be TRUE (remember
that you can find which variables are fixed all at once by using the By
type command under the Find button).
\end_layout
\begin_layout Itemize
Finally export v to the Solver.
The Eligible window should NOT appear; rather that Solver should report
the model to be square.
\end_layout
\begin_layout Itemize
Solve by selecting Solve under the Execute button.
\end_layout
\begin_layout Standard
The inclusion of methods has made the process of making this model much
easier to get well-posed.
This approach is the one that works for really large, complex models.
\end_layout
\begin_layout Section
Parameterizing the vessel model
\begin_inset LatexCommand \label{sec:model2.parameterizingVessel}
\end_inset
\end_layout
\begin_layout Standard
\begin_inset Marginal
status collapsed
\begin_layout Standard
let's compute metal_mass vs.
H_to_D_ratio
\end_layout
\end_inset
Reuse generally implies creating a model which will have as a part an instance
of a previously defined type.
For example, let us compute metal_mass as a function of the H_to_D_ratio
for a vessel for a fixed vessel_volume.
We would like to see if there is a value for the H_to_D_ratio for which
the metal_mass is minimum for a vessel with a given vessel_volume.
We might wonder if metal_mass goes to infinity as this ratio goes either
to zero or infinity.
\end_layout
\begin_layout Subsection
Creating a parameterized version of vessel
\end_layout
\begin_layout Standard
\begin_inset Marginal
status collapsed
\begin_layout Standard
parameters indicate likely object sharing
\end_layout
\end_inset
To use instances of our model as parts in another model, we can parameterize
it.
We use parameterization to tell a future user that the parameters are objects
he or she is likely to share among many different parts of a model.
We wish to create a table containing different values of H_to_D_ratio vs.
metal_mass.
We can accomplish this by computing simultaneously several different vessels
having the same vessel_volume, wall_thickness and metal_density.
The objects we want to see and/or share for each instance of a vessel should
include, therefore: H_to_D_ratio, metal_mass, metal_density, vessel_volume
and wall_thickness.
\end_layout
\begin_layout Standard
The code in Figure
\begin_inset LatexCommand \ref{fig:model2.parameterizedVessel}
\end_inset
\noun off
indicates the changes we make to the model declaration statement and the
statements defining the variables to parameterize our model.
\end_layout
\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open
\begin_layout LyX-Code
REQUIRE "atoms.a4l";
\end_layout
\begin_layout LyX-Code
MODEL vessel(
\end_layout
\begin_layout LyX-Code
vessel_vol "the volume contained within the cylindrical vessel"
\end_layout
\begin_layout LyX-Code
WILL_BE volume;
\end_layout
\begin_layout LyX-Code
wall_thickness "the thickness of all of the vessel walls"
\end_layout
\begin_layout LyX-Code
WILL_BE distance;
\end_layout
\begin_layout LyX-Code
metal_density "density of the metal from which the vessel
\end_layout
\begin_layout LyX-Code
is constructed"
\end_layout
\begin_layout LyX-Code
WILL_BE mass_density;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio "the ratio of vessel height to diameter"
\end_layout
\begin_layout LyX-Code
WILL_BE factor;
\end_layout
\begin_layout LyX-Code
metal_mass "the mass of the metal in the walls of the vessel"
\end_layout
\begin_layout LyX-Code
WILL_BE mass;
\end_layout
\begin_layout LyX-Code
);
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'author' SELF {Arthur W.
Westerberg}
\end_layout
\begin_layout LyX-Code
'creation date' SELF {May, 1998}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
(* variables *)
\end_layout
\begin_layout LyX-Code
side_area "the area of the cylindrical side wall of the vessel",
\end_layout
\begin_layout LyX-Code
end_area "the area of the flat ends of the vessel"
\end_layout
\begin_layout LyX-Code
IS_A area;
\end_layout
\begin_layout LyX-Code
wall_vol "the volume of the walls for the vessel"
\end_layout
\begin_layout LyX-Code
IS_A volume;
\end_layout
\begin_layout LyX-Code
H "the vessel height (of the cylindrical side walls)",
\end_layout
\begin_layout LyX-Code
D "the vessel diameter"
\end_layout
\begin_layout LyX-Code
IS_A distance;
\end_layout
\begin_layout LyX-Code
(* equations *)
\end_layout
\begin_layout LyX-Code
FlatEnds:end_area = 1{PI} * D^2 / 4;
\end_layout
\begin_layout LyX-Code
Sides:side_area = 1{PI} * D * H;
\end_layout
\begin_layout LyX-Code
Cylinder:vessel_vol = end_area * H;
\end_layout
\begin_layout LyX-Code
Metal_volume:(side_area + 2 * end_area) * wall_thickness = wall_vol;
\end_layout
\begin_layout LyX-Code
HD_definition:D * H_to_D_ratio = H;
\end_layout
\begin_layout LyX-Code
VesselMass:metal_mass = metal_density * wall_vol;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
METHODS
\end_layout
\begin_layout LyX-Code
METHOD specify;
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to fix four variables and make the problem well-posed}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
vessel_vol.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
wall_thickness.fixed :=TRUE;
\end_layout
\begin_layout LyX-Code
metal_density.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
END specify;
\end_layout
\begin_layout LyX-Code
METHOD values;
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to set the values for the fixed variables}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio:=2;
\end_layout
\begin_layout LyX-Code
vessel_vol:=250 {ft^3};
\end_layout
\begin_layout LyX-Code
wall_thickness:=5 {mm};
\end_layout
\begin_layout LyX-Code
metal_density:=5000 {kg/m^3};
\end_layout
\begin_layout LyX-Code
END values;
\end_layout
\begin_layout LyX-Code
METHOD bound_self;
\end_layout
\begin_layout LyX-Code
END bound_self;
\end_layout
\begin_layout LyX-Code
METHOD bound_all;
\end_layout
\begin_layout LyX-Code
RUN bound_self;
\end_layout
\begin_layout LyX-Code
END bound_all;
\end_layout
\begin_layout LyX-Code
METHOD scale_self;
\end_layout
\begin_layout LyX-Code
END scale_self;
\end_layout
\begin_layout LyX-Code
METHOD scale_all;
\end_layout
\begin_layout LyX-Code
RUN scale_self;
\end_layout
\begin_layout LyX-Code
END scale_all;
\end_layout
\begin_layout LyX-Code
METHOD default_self;
\end_layout
\begin_layout LyX-Code
D:=1 {m};
\end_layout
\begin_layout LyX-Code
H:=1 {m};
\end_layout
\begin_layout LyX-Code
END default_self;
\end_layout
\begin_layout LyX-Code
METHOD default_all;
\end_layout
\begin_layout LyX-Code
RUN default_self;
\end_layout
\begin_layout LyX-Code
vessel_vol:=1 {m^3};
\end_layout
\begin_layout LyX-Code
wall_thickness:=5 {mm};
\end_layout
\begin_layout LyX-Code
metal_density:=5000 {kg/m^3};
\end_layout
\begin_layout LyX-Code
H_to_D_ratio:=1;
\end_layout
\begin_layout LyX-Code
END default_all;
\end_layout
\begin_layout LyX-Code
END vessel;
\end_layout
\begin_layout LyX-Code
ADD NOTES IN vessel;
\end_layout
\begin_layout LyX-Code
'description' SELF {This model relates the dimensions of a
\end_layout
\begin_layout LyX-Code
cylindrical vessel -- e.g., diameter, height and wall thickness
\end_layout
\begin_layout LyX-Code
to the volume of metal in the walls.
It uses a thin wall
\end_layout
\begin_layout LyX-Code
assumption -- i.e., that the volume of metal is the area of
\end_layout
\begin_layout LyX-Code
the vessel times the wall thickness.}
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to illustrate the insertion of notes into a model}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout Caption
\begin_inset LatexCommand \label{fig:model2.parameterizedVessel}
\end_inset
The parameterized version of vessel model (
\begin_inset LatexCommand \index{1014608}
\end_inset
vesselParams.a4c)sss
\end_layout
\end_inset
\end_layout
\begin_layout Standard
Substitute the statements in Figure
\begin_inset LatexCommand \ref{fig:model2.parameterizedVessel}
\end_inset
\noun off
for lines 2 through 9 in
\noun default
Figure
\noun off
\begin_inset LatexCommand \ref{fig:model2.vesselWithMethods}
\end_inset
.
Save the result in the file vesselParam.a4c.
\end_layout
\begin_layout Standard
Note the use of the
\begin_inset LatexCommand \index{1014610}
\end_inset
\begin_inset LatexCommand \index{1014609}
\end_inset
WILL_BE statement in the parameter list.
By declaring that the type of a parameter will be compatible with the types
shown, the compiler can tell immediately if a user of this model is passing
the wrong type of object when defining an instance of a vessel.
\end_layout
\begin_layout Subsection
Using the parameterized vessel model
\end_layout
\begin_layout Standard
\begin_inset Marginal
status collapsed
\begin_layout Standard
Creating a
\begin_inset LatexCommand \index{1014611}
\end_inset
table of metal_mass values vs.
H_to_D_ratio
\end_layout
\end_inset
A type definition will set up our table of H_to_D_ratio values vs.
metal_mass so we can observe approximately where it attains a minimum value.
ASCEND allows us to create arrays of instances of any type.
Here we shall create an array of vessels.
The type definition is shown in Figure
\begin_inset LatexCommand \ref{fig:model2.tabulatedVessel}
\end_inset
\noun off
.
Note that the line numbers are not a part of the actual code.
We include them here only so we can reference them as needed later.
\end_layout
\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open
\begin_layout LyX-Code
REQUIRE "atoms.a4l";
\end_layout
\begin_layout LyX-Code
MODEL vessel(
\end_layout
\begin_layout LyX-Code
vessel_vol "the volume contained within the cylindrical vessel"
\end_layout
\begin_layout LyX-Code
WILL_BE volume;
\end_layout
\begin_layout LyX-Code
wall_thickness "the thickness of all of the vessel walls"
\end_layout
\begin_layout LyX-Code
WILL_BE distance;
\end_layout
\begin_layout LyX-Code
metal_density "density of the metal from which the vessel
\end_layout
\begin_layout LyX-Code
is constructed"
\end_layout
\begin_layout LyX-Code
WILL_BE mass_density;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio "the ratio of vessel height to diameter"
\end_layout
\begin_layout LyX-Code
WILL_BE factor;
\end_layout
\begin_layout LyX-Code
metal_mass "the mass of the metal in the walls of the vessel"
\end_layout
\begin_layout LyX-Code
WILL_BE mass;
\end_layout
\begin_layout LyX-Code
);
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'author' SELF {Arthur W.
Westerberg}
\end_layout
\begin_layout LyX-Code
'creation date' SELF {May, 1998}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
(* variables *)
\end_layout
\begin_layout LyX-Code
side_area "the area of the cylindrical side wall of the vessel",
\end_layout
\begin_layout LyX-Code
end_area "the area of the flat ends of the vessel"
\end_layout
\begin_layout LyX-Code
IS_A area;
\end_layout
\begin_layout LyX-Code
wall_vol "the volume of the walls for the vessel"
\end_layout
\begin_layout LyX-Code
IS_A volume;
\end_layout
\begin_layout LyX-Code
H "the vessel height (of the cylindrical side walls)",
\end_layout
\begin_layout LyX-Code
D "the vessel diameter"
\end_layout
\begin_layout LyX-Code
IS_A distance;
\end_layout
\begin_layout LyX-Code
(* equations *)
\end_layout
\begin_layout LyX-Code
FlatEnds:end_area = 1{PI} * D^2 / 4;
\end_layout
\begin_layout LyX-Code
Sides:side_area = 1{PI} * D * H;
\end_layout
\begin_layout LyX-Code
Cylinder:vessel_vol = end_area * H;
\end_layout
\begin_layout LyX-Code
Metal_volume:(side_area + 2 * end_area) * wall_thickness = wall_vol;
\end_layout
\begin_layout LyX-Code
HD_definition:D * H_to_D_ratio = H;
\end_layout
\begin_layout LyX-Code
VesselMass:metal_mass = metal_density * wall_vol;
\end_layout
\begin_layout LyX-Code
METHODS
\end_layout
\begin_layout LyX-Code
METHOD specify;
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to fix four variables and make the problem well-posed}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
vessel_vol.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
wall_thickness.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
metal_density.fixed:=TRUE;
\end_layout
\begin_layout LyX-Code
END specify;
\end_layout
\begin_layout LyX-Code
METHOD values;
\end_layout
\begin_layout LyX-Code
NOTES
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to set the values for the fixed variables}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio:=2;
\end_layout
\begin_layout LyX-Code
vessel_vol:=250 {ft^3};
\end_layout
\begin_layout LyX-Code
wall_thickness:=5 {mm};
\end_layout
\begin_layout LyX-Code
metal_density:=5000 {kg/m^3};
\end_layout
\begin_layout LyX-Code
END values;
\end_layout
\begin_layout LyX-Code
METHOD bound_self;
\end_layout
\begin_layout LyX-Code
END bound_self;
\end_layout
\begin_layout LyX-Code
METHOD bound_all;
\end_layout
\begin_layout LyX-Code
RUN bound_self;
\end_layout
\begin_layout LyX-Code
END bound_all;
\end_layout
\begin_layout LyX-Code
METHOD scale_self;
\end_layout
\begin_layout LyX-Code
END scale_self;
\end_layout
\begin_layout LyX-Code
METHOD scale_all;
\end_layout
\begin_layout LyX-Code
RUN scale_self;
\end_layout
\begin_layout LyX-Code
END scale_all;
\end_layout
\begin_layout LyX-Code
METHOD default_self;
\end_layout
\begin_layout LyX-Code
D:= 1 {m};
\end_layout
\begin_layout LyX-Code
H:=1 {m};
\end_layout
\begin_layout LyX-Code
END default_self;
\end_layout
\begin_layout LyX-Code
METHOD default_all;
\end_layout
\begin_layout LyX-Code
RUN default_self;
\end_layout
\begin_layout LyX-Code
vessel_vol:=1 {m^3};
\end_layout
\begin_layout LyX-Code
wall_thickness:=5 {mm};
\end_layout
\begin_layout LyX-Code
metal_density:=5000 {kg/m^3};
\end_layout
\begin_layout LyX-Code
H_to_D_ratio:=1;
\end_layout
\begin_layout LyX-Code
END default_all;
\end_layout
\begin_layout LyX-Code
END vessel;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
ADD NOTES IN vessel;
\end_layout
\begin_layout LyX-Code
'description' SELF {This model relates the dimensions of a
\end_layout
\begin_layout LyX-Code
cylindrical vessel -- e.g., diameter, height and wall thickness
\end_layout
\begin_layout LyX-Code
to the volume of metal in the walls.
It uses a thin wall
\end_layout
\begin_layout LyX-Code
assumption -- i.e., that the volume of metal is the area of
\end_layout
\begin_layout LyX-Code
the vessel times the wall thickness.}
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to illustrate the insertion of notes into a model}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
MODEL tabulated_vessel_values;
\end_layout
\begin_layout LyX-Code
vessel_volume "volume of all the tabulated vessels"
\end_layout
\begin_layout LyX-Code
IS_A volume;
\end_layout
\begin_layout LyX-Code
wall_thickness "thickness of all the walls for all the vessels"
\end_layout
\begin_layout LyX-Code
IS_A distance;
\end_layout
\begin_layout LyX-Code
metal_density "density of metal used for all vessels"
\end_layout
\begin_layout LyX-Code
IS_A mass_density;
\end_layout
\begin_layout LyX-Code
n_entries "number of vessels to simulate"
\end_layout
\begin_layout LyX-Code
IS_A integer_constant;
\end_layout
\begin_layout LyX-Code
n_entries :== 20;
\end_layout
\begin_layout LyX-Code
H_to_D_ratio[1..n_entries]"set of H to D ratios for which we are
\end_layout
\begin_layout LyX-Code
computing metal mass"
\end_layout
\begin_layout LyX-Code
IS_A factor;
\end_layout
\begin_layout LyX-Code
metal_mass[1..n_entries]"mass of metal in walls of vessels"
\end_layout
\begin_layout LyX-Code
IS_A mass;
\end_layout
\begin_layout LyX-Code
FOR i IN [1..n_entries] CREATE
\end_layout
\begin_layout LyX-Code
v[i] "the i-th vessel model"
\end_layout
\begin_layout LyX-Code
IS_A vessel(vessel_volume, wall_thickness,
\end_layout
\begin_layout LyX-Code
metal_density, H_to_D_ratio[i], metal_mass[i]);
\end_layout
\begin_layout LyX-Code
END FOR;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
METHODS
\end_layout
\begin_layout LyX-Code
METHOD default_self;
\end_layout
\begin_layout LyX-Code
END default_self;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
METHOD specify;
\end_layout
\begin_layout LyX-Code
RUN v[1..n_entries].specify;
\end_layout
\begin_layout LyX-Code
END specify;
\end_layout
\begin_layout LyX-Code
METHOD values;
\end_layout
\begin_layout LyX-Code
NOTES 'purpose' SELF {to set up 20 vessel models having H to D ratios
\end_layout
\begin_layout LyX-Code
ranging from 0.1 to 2.}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout LyX-Code
vessel_volume := 250 {ft^3};
\end_layout
\begin_layout LyX-Code
wall_thickness := 5 {mm};
\end_layout
\begin_layout LyX-Code
metal_density := 5000 {kg/m^3};
\end_layout
\begin_layout LyX-Code
FOR i IN [1..n_entries] DO
\end_layout
\begin_layout LyX-Code
H_to_D_ratio[i] := i/10.0;
\end_layout
\begin_layout LyX-Code
END FOR;
\end_layout
\begin_layout LyX-Code
END values;
\end_layout
\begin_layout LyX-Code
METHOD scale_self;
\end_layout
\begin_layout LyX-Code
END scale_self;
\end_layout
\begin_layout LyX-Code
END tabulated_vessel_values;
\end_layout
\begin_layout LyX-Code
\end_layout
\begin_layout LyX-Code
ADD NOTES IN tabulated_vessel_values;
\end_layout
\begin_layout LyX-Code
'description' SELF {This model sets up an array of vessels to
\end_layout
\begin_layout LyX-Code
compute a range of metal_mass values for different values
\end_layout
\begin_layout LyX-Code
of H_to_D_ratio.}
\end_layout
\begin_layout LyX-Code
'purpose' SELF {to illustrate the use of arrays in ASCEND}
\end_layout
\begin_layout LyX-Code
END NOTES;
\end_layout
\begin_layout Caption
tabulated_vessel_values model
\begin_inset LatexCommand \label{fig:model2.tabulatedVessel}
\end_inset
\end_layout
\end_inset
\end_layout
\begin_layout Standard
Add this model to the end of the file
\family typewriter
vesselParam.a4c
\family default
\begin_inset LatexCommand \index{vesselTabulated.a4c}
\end_inset
(after the vessel model) and save the file as
\family typewriter
vesselTabulated.a4c
\family default
.
Compile an instance of tabulated_vessel_values (call it tvv), run the values
and specify methods for it, and then solve it.
You will discover that the tenth element of the metal_mass array, corresponding
to an
\family typewriter
H_to_D_ratio
\family default
of 1 has the minimum value of 510.257 kilograms.
\end_layout
\begin_layout Section
Creating a script
\begin_inset LatexCommand \index{script, creating}
\end_inset
to demonstrate this model
\begin_inset LatexCommand \label{sec:model2.creatingScript}
\end_inset
\end_layout
\begin_layout Standard
The last step to make the model reusable is to create a script that anyone
can easily run.
Running the model successfully will allow a user to demonstrate the use
of the model and to explore an instance it by browsing it.
\end_layout
\begin_layout Standard
ASCEND allows one to create such a script using either an editor or the
tools in the Script window.
\end_layout
\begin_layout Standard
Restart the ASCEND system.
You will have three windows open plus the large one which disappears by
itself in a few seconds: the Script, the Library and the Console windows.
\end_layout
\begin_layout Standard
In the
\series bold
Script
\series default
window you will see the license agreement information for ASCEND.
First delete the license agreement
\begin_inset LatexCommand \index{license agreement}
\end_inset
from this window by doing the following two steps:
\end_layout
\begin_layout Itemize
Select the Select all tool under the Edit button.
\end_layout
\begin_layout Itemize
Then select the Delete statements tool under the same button.
\end_layout
\begin_layout Standard
With the window
\series bold
clear
\series default
, select the tool Record actions under the Edit button to start recording
the steps you are about to undertake.
\end_layout
\begin_layout Itemize
In the Library window, under the Edit button, selec Delete all types.
Hit Delete all on the small window that appears.
\end_layout
\begin_layout Itemize
Load the file vesselTabulated.a4c, the file containing the model called tabulated
_vessel_values.
Do this by selecting the Read types from file tool under the File button
and browsing the file system to find it.
If you have trouble finding it, be sure to set the Files of type window
at the bottom of the file browsing window to allow all types of files to
be seen.
\end_layout
\begin_layout Itemize
Select the type tabulated_vessel_values in the right Library window and
compile an instance of it by selecting the Create simulation tool under
the Edit button.
In the small window that appears, enter the name tvv and hit OK.
\end_layout
\begin_layout Itemize
Export the instance to the Browser by selecting the Simulation to Browser
tool under the Export button.
\end_layout
\begin_layout Itemize
Initialize the variable values by running the values method.
Do this by selecting the Run method tool under the Edit button.
Select the values method and hit OK.
\end_layout
\begin_layout Itemize
Set the fixed flags to get a well-posed problem by repeating the last step
but this time select the reset method.
\end_layout
\begin_layout Itemize
Export the instance tvv to the Solver by selecting the to Solver tool under
the Export button.
\end_layout
\begin_layout Itemize
Solve tvv by selecting the Solve tool under the Execute button in the Solver
window.
\end_layout
\begin_layout Itemize
Return to the Script window and turn off the recording by selecting the
Record actions tool under the Edit button.
\end_layout
\begin_layout Itemize
Save the script you have just created by selecting the Save tool under the
File button of the Script window.
Name the file vesselTabulated.a4s (note the 's' ending) to indicate it is
the script to run an example problem for models in the vesselTabulated.a4c
(note the 'c' ending) file.
\end_layout
\begin_layout Itemize
Exit ASCEND by selecting the Exit ASCEND tool under the File button on the
Script window.
The contents of the Script window will be similar to that in Figure
\begin_inset LatexCommand \ref{fig:model2.scriptVesselTabulated}
\end_inset
\noun off
(the path to the file may differ).
\end_layout
\begin_layout Itemize
Restart ASCEND.
\end_layout
\begin_layout Itemize
Open the script you just created by selecting the Read file tool under the
File button on the Script window.
(Be sure you are allowing the system to see files with the ending a4s by
setting the Files of type window at the bottom of the file browsing window.)
\end_layout
\begin_layout Itemize
Highlight all the instructions in this script and then execute the highlighted
instructions by selecting the Statements selected tool under the Execute
button.
\end_layout
\begin_layout Standard
You will run the same sequence of instructions you ran to create the script.
\end_layout
\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open
\begin_layout LyX-Code
DELETE TYPES;
\end_layout
\begin_layout LyX-Code
READ FILE "C:/My Documents/1998/ascdata/vesselTabulated.a4c";
\end_layout
\begin_layout LyX-Code
COMPILE tv OF tabulated_vessel_values;
\end_layout
\begin_layout LyX-Code
BROWSE {tv};
\end_layout
\begin_layout LyX-Code
RUN {tv.reset};
\end_layout
\begin_layout LyX-Code
RUN {tv.values};
\end_layout
\begin_layout LyX-Code
SOLVE {tv} WITH QRSlv;
\end_layout
\begin_layout Caption
Script to run vesselTabulated.a4c (this is the contents of the file vesselTabulat
ed.a4s
\begin_inset LatexCommand \index{vesselTabultated.a4s}
\end_inset
)
\begin_inset LatexCommand \label{fig:model2.scriptVesselTabulated}
\end_inset
\end_layout
\end_inset
\end_layout
\begin_layout Section
Discussion
\end_layout
\begin_layout Standard
In this chapter we converted the vessel model into a form where you and
others in the future will have a chance to reuse it.
We did this by first adding methods to make the problem well-posed and
to provide values for the fixed variables for which we readily found a
solution when playing with our original model as we did in the previous
chapter.
We then thought of a typical use for this model and developed a parameterized
version based on that use.
If this model were in a library, a future user of it would most often simply
have to understand the parameters to create an instance of this type of
model.
We next added NOTES, a form of active comments, to the model.
We suggest that notes are much more useful than comments as we can provide
tools that can extract them and allow us to search them, for example, to
find a model with a given functionality.
Finally, we showed you how to create a script by turning on a "phone" session
where ASCEND records the actions one takes when loading, compiling and
solving a model.
One can save and play this script in the future to see a typical use of
the model.
\end_layout
\begin_layout Standard
In the next chapter, we look at how we can plot the results we created in
the model vesselTabulated.a4c.
We will have to reuse a model someone else has put into the library of
available models.
In other words, the "shoe is on the other foot," and we quickly experience
the difficulties with reuse first hand.
We will also learn how to run a case study from which we can extract the
same information with a single vessel model run multiple times.
\end_layout
\end_body
\end_document