trunk/doc/howto-model2.lyx

#LyX 1.4.1 created this file. For more info see http://www.lyx.org/
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\textclass book
\language english
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\output_changes true
\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
<lyxtabular version="3" rows="5" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="1.25in">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="3.5in">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\family typewriter
ClearAll
\family default

\begin_inset LatexCommand \index{ClearAll}

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\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
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\family typewriter
specify
\family default

\begin_inset LatexCommand \index{specify}

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\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
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\family typewriter
reset
\family default

\begin_inset LatexCommand \index{reset}

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\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
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\family typewriter
values
\family default

\begin_inset LatexCommand \index{values}

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\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
</cell>
</row>
</lyxtabular>

\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 �well-posed.� 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 �standard� 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
<lyxtabular version="3" rows="5" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="1.25in">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="3.5in">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
method
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
description
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\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
</cell>
<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none" width="3.5in">
\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
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\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
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\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
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\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
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\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
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\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
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\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
</cell>
</row>
</lyxtabular>

\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