CHAPTER 2
SIMPROCESS Basics

A SIMPROCESS model contains the following components:

· Processes

· Activities

· Entities

· Resources

· Connectors

· Pads

Processes and Activities represent business operations in a SIMPROCESS model. SIMPROCESS models can be arranged in a hierarchy, with Processes encompassing other Processes and Activities.

SIMPROCESS Components

Processes

A set of Processes can represent the operation of a business at a very high level. This level represents only an outline of the business Process.

Activities represent the details of business operations. For example, in a mail order fulfillment operation, when a customer order is received, processing steps might include:

1. Identifying the customer.

2. Creating or accessing a customer profile.

3. Verifying the customer profile against information contained in the customer's order.

Each of these steps can be modeled as an Activity. Collectively, they comprise a single Process that might be called "Access/Create Customer Profile."

The Process construct allows a business Process to be broken down into successively more detailed layers.

A Process can be (and usually is) composed of other Processes and Activities. Activities cannot be decomposed.

Activities

SIMPROCESS contains a suite of Activities, each reflecting a different type of action. Actions can be physical or logical.

Entities

Entities are objects that circulate through the model. They represent things (e.g., parts, deliveries, people) and information (orders, service requests, etc.) that flow from Activity to Activity. The customer order is an Entity in the order fulfillment process.

Unlike Processes and Activities, which appear as icons in the model layout, Entities aren't visible until a simulation is run. During the simulation, they emerge as icons flowing through the model, if animation is turned on.

Resources

Resources are the agents that add value to Entities or perform work at Activities. Examples include:

· A customer calls in an order, which requires a clerk to handle it. Order entry is the Activity, the order is an Entity, and the clerk is a Resource.

· A truck is required to deliver merchandise to the customer; the truck is a Resource.

The way to minimize cycle time and Activity costs is by experimenting with different levels of Resources and different costs.

The availability of a Resource affects the amount of time it takes an Entity to flow through the Process. Lack of Resources can be a cause of bottlenecks in a business Process. A customer order might arrive while two clerks are busy handling other tasks. Order fulfillment is delayed until a clerk becomes available. The amount of time the customer order spends waiting for an available clerk is shown in the Entity Cycle Time by State output report as Wait for Resource. Another way to describe this situation is that the order waited in a queue for the available Resource.

Knowing how Resources are used is a key factor in understanding and improving upon the way a business operates.

Connectors

Connectors link Activities and Processes together and are the paths used by Entities to flow through the model. Connectors can have delay times.

Connector Names

A default Connector name, e.g., Conn44 is assigned. To change the Connector Name, edit the Name field in the Connector properties.

Displaying Connector Names

The Edit Preferences option, on the Edit menu, determines if names of new Connectors are displayed in the model. However, individual Connector dialogs have Show Name check boxes that will override the model default.

The Name field is displayed across the middle of the Connector if Show Name is selected.

Display Properties

The Line Width and Line Style properties control the appearance of the Connector. Defaults for Line Width and Line Style can be set in the Preferences. See "Preferences" on page 30.

Duration

A Connector defaults to no Duration. Duration can be specified by setting a Travel Time or by Distance Divided By Rate. If using Distance Divided By Rate, a value must be set for Distance and Rate, and Rate must not be zero. No units are assumed for Distance or Rate. The Units field applies to the value that results from Distance being divided by Rate.

Note that a Connector Duration affects Entity animation. When no Connectors on a layout have a Duration, one Entity moves at a time. This is because the Entity movement occurs in zero simulation time. However, when Connectors on a layout have a Duration, multiple Entities can be moving at the same time since the movement represents the passing of time. If some Connectors on a layout have a Duration and some do not, the movement of Entities on Connectors with a Duration will stop while Entities cross Connectors with no Duration. The Units set for Travel Time or Distance Divided By Rate also affect the animation of Entity movement. It is recommended (for animation purposes only) that the Units of the Connector Duration match the Simulation Time Unit on the Run Settings dialog. (See "Setting the Simulation Time Unit" on page 89.) If the Simulation Time Unit is different from the Units of a Connector Duration, then it is possible that either the Entities will move very slowly across the Connector no matter what Animation Speed (page 57) is set or the Entities will never show up (again, no matter what Animation Speed is set). If animation is not a consideration, then any value for Units is valid.

Connector Statistics

Collect Connector Statistics and Collect Connector by Entity Statistics are used to request statistics for the specified Connector. See "Connector Statistics," beginning on page 198 for more information.

Pads

Pads are small triangular objects attached to Activities and Processes which serve as attachment points for Connectors. A single Pad can connect one or (possibly) more Connectors. Entities flow in one direction, entering nodes at input Pads and exiting at output Pads. Three sizes of Pads are available: small, medium, and large. The Pad size can be changed on the Pad properties dialog, or by right clicking on the Pad and choosing Pad Size. The size of all the Pads on an Activity or selected Activities can be changed by right clicking on a selected Activity and choosing Pad Size.

Pads also connect one level of a Process hierarchy to another. Pads can be queueing areas for Entities waiting for a Resource or condition.

Putting it Together

A SIMPROCESS model shows a business Process as a set of Nodes (Processes and Activities) connected by Connectors. Entities are generated from one or more Generate Activities, traverse the model, and finally proceed to a Dispose Activity, where they are disposed. Entities pass through other Activities, such as Delays and Branches.

A model is built by supplying numeric and symbolic attributes to the various Activities and the Entities that are processed at these Activities. The Resources needed to process the Entities are also defined.

The end result is a dynamic model of the business Process. Bottlenecks can be seen as they occur when simulations are run on this model. Reports and statistics may be generated describing the flow of people, materials, and information and quantifying how Resources are used. The model may continue to be modified in order to experiment with different scenarios.

A simple model can be built with just three Activity objects: Generate, Delay, and Dispose.

All models require a Generate Activity to generate Entities and a Dispose Activity to end the processing of Entities. Delay Activities are used to represent actions.

There are some things that are common to most Activities, such as the Activity name and Resources required by the Activity. This chapter begins with a discussion of the input fields and command buttons used to define these items. The remainder of the chapter describes the core SIMPROCESS Activities in detail, with particular attention devoted to the Generate Activity and the Entities.

The remaining SIMPROCESS Activities are described in Chapter 4-Activity Modeling Constructs, beginning on page 118, and in "Explicitly Getting and Freeing Resources" on page 155.

Using the Layout Toolbar to Create Activities

The Layout Toolbar is the two columns of buttons running down the left margin of the SIMPROCESS window. These buttons are used to place model building blocks on the SIMPROCESS layout - the central region of the SIMPROCESS window.

Begin by adding a Generate Activity to the model. Click once on the Generate Activity button.

Next, point and click on the SIMPROCESS layout. A Generate Activity icon is added at that location.

Press and hold the Shift key while clicking on the layout to add several activities of the same type, i.e., Generate. Each time the layout is clicked, a Generate icon is added to the layout. Release the Shift key before dropping the last icon or click once on the Select tool to deactivate the Generate button.

Removing Objects from the Layout

Select an object such as an Activity icon from the layout and press the Delete key. Several items may be removed at one time by drawing a rectangle around the objects and pressing Delete or selecting Edit/Clear from the menu or the popup menu.

Common Activity Input Fields

Activity Properties dialogs have the following common input fields:

· Name is the name chosen to identify the Activity. This name appears below the Activity, and it can be moved on the layout.

· Icon identifies the graphic icon representing the Activity.

· Comment is a one-line comment about the Activity. This comment appears in the status bar when the Activity is selected.

· Documentation tab contains a Document... button that opens an edit window for adding descriptive text about the Activity. See "document Subdirectory" on page 474 for information on customizing headings. Next to the Document... button is the Metadata... button. The Metadata... button opens a dialog for entering metadata. See Chapter 4 of the SIMPROCESS Metadata Manual for a full discussion of entering SIMPROCESS metadata. This tab also contains a field for adding a link to a URL or another document. (See "Export" on page 23.) The View button launches the preferred web browser if Is URL is selected. If Is URL is not selected, SIMPROCESS assumes the URL is a file and will attempt to open the file with whatever program is designated to open that type of file. For Windows, the View button enables when Is URL is selected and the URL/File field is not empty, or Is URL is not selected and the URL/File field indicates a path (contains backslashes or begins with ./). The same conditions apply on Linux systems. In addition, on Linux, the view.properties file must be in the SPUser directory, and the view.properties file must contain valid url.view and file.view properties. Due to other applications being required, the View button is not guaranteed to work in every case.

· Attributes define custom attributes that the Activity requires. This topic is covered extensively in Chapter 10, "Customizing a Model with Attributes and Expressions," beginning on page 237.

· Expressions allow customized processing for the Activity at various points during a simulation. This topic is covered in detail in Chapter 10, "Customizing a Model with Attributes and Expressions," beginning on page 237.

· Event Logs are used for defining timestamps and recorders.

· Text Block is a three-line description that appears within the Activity's icon on the layout.

· Help displays information about the Activity.

The following tabs and fields are found on most Activity Properties dialogs:

· Resources defines the Resources required to process Entities arriving at the Activity. The Entity waits in a queue until the Resource or Resources can be obtained.

· Duration/Value is the amount of time it takes the Activity to process an Entity, once the required Resources are obtained. Time can be defined as a constant, or as a statistical distribution.

· Duration/Time Units specifies the units and measure for duration time in nanoseconds, microseconds, milliseconds, seconds, minutes, hours, days, weeks, months, or years.

The following buttons are found on all Activity Properties dialogs except Background Text. These buttons allow the creation of items that are then available throughout the model.

· New Entity creates new Entity types.

· New Resource creates new Resource types.

· Entity creates new global Entity instance attributes.

· Entity Type creates new global Entity Type attributes.

· Resource creates new global Resource attributes.

· Model creates new Model attributes.

Attributes are covered extensively in Chapter 10, "Customizing a Model with Attributes and Expressions," beginning on page 237.

Naming Activities

Use the Name field to assign a name to an Activity. This name is shown below the Activity icon in the model if the Show Name checkbox is selected.

SIMPROCESS assigns new Activities a default name. It is a good idea to change this to a name that is meaningful; one that indicates what occurs at this Activity. Activities can be named just about anything, as long as the same name is not used twice in the same level of the model hierarchy.

Change the name of an existing Activity by clicking in the Name field and typing the new name.

The contents of the Text Block can be used as the Name by selecting the Use Text Block check box. The lines of text are appended together with a space between each line to create the Name. When Use Text Block is selected, the Name field is not editable. The values on the Text Block tab must be changed to change the Name.

Choosing an Icon

The Icon field identifies the graphical icon used to represent the Activity in the model layout. All Activity icons are arranged into sets. The set consists of predefined sets and user defined sets. (See "Importing Graphics Image Files" on page 168.) The Icon Set field lists the sets of icons available. The set All lists all icons regardless of set. Every Activity has several icons from which to choose. The names of the standard icons differ slightly for each Activity, because they include the name of the Activity.

Point and click on and icon's name to select it. The icon button on the right gives a reduced view of the icon. Click the icon button to see the actual size. GIF, JPG, and PNG files may be imported and used as custom icons for Activities.

Adding a Comment

Use the Comment field to add a brief comment describing the purpose of this Activity. This field is optional. Printing Process Documentation or Model Documentation will include comment in the document. The comment will appear on the status bar when an Activity is selected.

Documenting the Activity

The Document button opens an editor in which descriptive information may be added about the Activity. The editor opens with a preformatted template which is changeable. (See "document Subdirectory" on page 474.) Print Document text using the SIMPROCESS Print facility.

Labeling with Text Blocks

The Text Block tab adds up to three lines of text to the inside of the icon on the layout.

Text Block labels facilitate understanding of the Activity or Process in relation to the model.

Add descriptive labels to an icon by performing the following tasks:

1. Click on Text Block tab:

2. Fill in one to three lines of text.

3. Set the desired font attributes.

4. Make sure the Show Text Box is checked. The text entered is not displayed in the model unless this box is not checked.

5. Click on OK.

Note: The Text Block is best used with blank box icons. Icons with a picture on them will not show the Text Block properly.

Process properties include an additional option on the Text Block tab. The Add Text Label check box places a label that contains the text of the Text Block inside each alternative of the Process.

The lines of text are appended together with a space between each line to create the label. Select the Properties button to set whether the label should be displayed horizonally or vertically and to set the Font Attributes of the label.

The label will be centered across the top of the layout when Horizontal is selected, and the label will be centered along the left of the layout when Vertical is selected. Note that the labels cannot be resized or moved. Changes can only be made from the Text Block tab of the Process properties dialog. Defaults for Horizontal or Vertical and the Font Attributes can be set on the Text Label tab of the Preferences dialog (Edit/Preferences).

Getting Help

The Help button displays information about the purpose of the Activity and the fields and buttons on the General tab of the dialog. The other tabs have Help buttons that are specific to that tab.

Generate Activity

Generate Activities create Entities for a model during a SIMPROCESS simulation. Generally, the first Activity defined in the model is a Generate.

SIMPROCESS generates Entities at the rate defined in the Generate Activity. Entities can be generated at a constant number and rate, such as a specified interval of time, or according to a statistical distribution. The schedule of generation can be as simple as one constant rate, or as complex as dozens of different rates depending on the hour of the day, day of the week, season of the year, etc.

A Generate Activity can generate one or more types of Entities

Defining a Basic Generate Activity

Click on the Entity pull-down arrow to select the default type of Entity to be generated by this Generate Activity. The default Entity type can be overridden in each schedule.

Entities may be defined using the New Entity command button on this dialog.

Use the Quantity field to specify the default number of Entities to be generated each time Entities are released. A specific number or probability distribution can be entered in the Quantity field or a selection may be made from the Quantity pull-down list. The default quantity can be overridden in each schedule.

A periodic schedule is the default schedule. The periodic schedule sets the interval and the time unit. It will default to an interval of 1.0 and time unit of Hours. These defaults can be changed by selecting the schedule (Periodic1) and choosing Edit. Change the name of the schedule, override the default Entity type and quantity, and set the interval and time unit with this method.

The Interval field defines the time between Entity generation events. Enter a constant value or a statistical distribution. Entities are generated at the end of each interval:

For example, assume Customer Orders to arrive at an exponential rate, with an average of 20 arrivals per hour. Click on the Interval pull-down arrow and find the definition for Exponential Distributions. It reads:

Exp(10.0)

Select the distribution. Then, click on the details button to the right of the pull-down arrow.

This displays a dialog for defining the parameters of the distribution:

Set the Mean value to indicate an average Entity generation rate of 20 per hour.

Assume that Quantity is 1, meaning that only one Entity is produced at each Entity generation event:

· Generate an Entity every 3 minutes to get 20 Entities in an hour (60 minutes).

The View button displays a graphical representation of the distribution:

Stream identifies the random number stream used to seed the distribution.

More can be learned about statistical distributions and random number streams in Chapter 3, "Statistical Modeling Constructs," beginning on page 94.

Delay Activity

Delay Activities, common building blocks found in most models, have two functions: they represent the passage of time during simulation and define the Resources required to perform a task. The cycle time of an Entity traversing the model is the sum of the delays it encounters, i.e., the time spent at the Activities in its path plus any hold time for a condition to be met and the wait time for any Resources.

The Resources button opens a dialog for specifying the Resources required to perform an Activity. See Chapter 5, "Resource Modeling Constructs," beginning on page 147 for instructions on defining Resource requirements for an Activity.

Specifying Delay Duration

Value represents the amount of time required to perform an Activity. This delay time can be expressed as either a constant value or a statistical distribution.

Time Units determines if the Duration entered is measured as nanoseconds, microseconds, milliseconds, seconds, minutes, hours, days, weeks, months, or years.

Type the value of the delay duration directly in the field, or select a value from a pull-down list.

A Delay Activity might be defined to represent the task of processing an order. This task takes an average of 30 minutes to perform, though it may take as little as 15 minutes, or as much as 1 hour.

As shown below, a Triangular distribution is often used to represent the time required to complete a task:

1. Click on the arrow to the right of the Value field to display a list of distributions:

2. Scroll through the list to find the default definition for Triangular distributions. It reads:

Tri(0.0,5.0,10.0)

Select the distribution.

3. Click on the box to the right of the Value field. Fill in the following values:

· Minimum of 15, Mode of 30, and a Maximum of 60.

· Select Minutes from the Units field.

4. Click on View to see what the curve looks like.

5. Click on OK to accept the definition.

See Chapter 3, "Statistical Modeling Constructs," beginning on page 94 to learn more about these parameters and the topic of statistical distributions.

Dispose Activity

A Dispose Activity disposes of Entities when they are no longer needed in the simulation. The Dispose marks the end of an Entity's cycle time for the purpose of statistic collection (e.g., cycle times and counts).

Dispose Activity Properties

The Dispose Activity Properties dialog contains only one unique field: Maximum Entity Count. Use this field to set a limit to the number of Entities that can be disposed of at the Dispose during a simulation. The simulation ends if this limit is reached. End a simulation after 1,000 customer orders are processed by setting Maximum Entity Count to 1,000.

Leaving Maximum Entity Count undefined or setting a value of 0 or "none" indicates that there is no limit.

Defining an Entity

A particular type of Entity or a particular instance of an Entity may be referred to in the model. When an Entity type is referred to, all Entities of a particular type, e.g., customer orders are also referred. An Entity instance refers to an individual Entity (a single customer order).

Defining Entities in SIMPROCESS defines a type; SIMPROCESS generates instances of that Entity during a simulation run. Define Entities in the following manner:

1. Click on Define on the SIMPROCESS menu, and then select Entities... from the pull-down menu.

2. Click on Add to define a new Entity.

3. Specify the Entity Type Properties:

· Entity Name identifies the type of Entity. Name can be any unique entity name.

Double-click on the default name supplied by SIMPROCESS, and enter Customer Order as the Entity Name.

· Entity Icon is the icon which will represent this Entity during a simulation run. The icon appears during simulation if the Animation option is on.

Click on the downward-pointing arrowhead next to the Entity Icon field to get a list of different icons to choose from the currently selected Icon Set.

· Priority values range from 1 to 100. When Entities contend for the same Resource, the Entity with the highest priority gets precedence.

· Preempt Lower Priority Entities sets whether instances of this type will preempt lower priority Entities. If true, when an instance of this type reaches an Activity that uses Resources and there are no Resources available, and the Entity currently using the Resources is a lower priority Entity, this higher priority arriving entity instance will cause the lower priority Entity to release the Resources so this Entity can obtain the Resources and Process.

· Entity Attributes, Entity Type Attributes, Entity Expressions, and Entity Type Expressions are used in association with any attributes or expressions defined for this Entity. A choice can be made to create a new copy of an attribute or evaluate an expression every time an instance of an Entity is created. Alternatively, one copy of an attribute can be created or an expression evaluated once for an Entity type and have all instances refer to this value. Attributes and expressions are discussed in Chapter 10, "Customizing a Model with Attributes and Expressions," beginning on page 237.

· Document... opens an editor window into which extensive comments can be entered about the Entity and the model. This is optional. The Entity document headings can be customized. (See "document Subdirectory" on page 474.)

· Metadata... opens a dialog for metadata entry. See the SIMPROCESS Metadata Manual for information on using metadata in a SIMPROCESS model.

· Comment is used to enter brief text describing the purpose of the Entity.

4. Click on OK when data entry is completed. The defined Entity is added to the table in the Entities dialog.

5. Add another Entity and name it Shipment. Click on the pull-down arrow next to the Icon field to get a list of Entity icons.

The list may be a lot longer than it first appears. Click near the top of the scroll bar to see more list items. Select GreenDot. Then click on OK. The icon selected will appear on the button next to the icon list. Clicking the button will bring a dialog that shows the default size of the icon.

Note that the basic properties of Entities added to the model can be edited directly from the table. However, changes made in the table are direct changes to the properties of the Entity and cannot be canceled. Also, the table can be sorted by a particular column by clicking on the column header. Holding the Shift key while clicking on a column header causes the table to sort in the reverse order.

Copy the properties of an existing Entity (such as the one just defined) by selecting the Entity in the table and click on the Copy button. Enter a different Entity Name and make any other changes on the Entity Type Properties screen, and then click on OK.

Remove an existing Entity by selecting the Entity and clicking on the Remove button. The Undo button restores Entity definitions that have been removed. Click on Close when Entities are defined.

Defining Resources and Processes

Resources

The next thing to define in the model are the Resources required to process Customer Order Entities. To keep things simple, define just one Resource, the clerks needed to process customer orders.

1. Select Resources... from the Define pull-down menu.

2. Select Add to define a new Resource.

See Chapter 5, "Resource Modeling Constructs," beginning on page 147 for an explanation of the remaining options and commands, and for more details on defining Resources, including pre-defined Resource types.

Processes

A SIMPROCESS Process defines Processes hierarchically. In this example, we will define a Process that indicates how customer orders are handled

Select the Process button from the Layout Toolbar and click on the layout.

Display a dialog for defining the Process. Do this by either:

· Clicking on the Process icon to select it, and then pressing Alt+Enter

· Selecting the Process icon, and then selecting Edit from the menu bar, followed by Properties...

Alternative Sub-Processes

A Process may consist of a set of Alternative sub-processes. Each sub-process can represent an alternative implementation of the Process. This allows the creation of many variations of a Process and keeps them organized in one place.

Only one sub-process can be active at any point in time. An experiment may be run with Alternative sub-process 1 active to measure the overall performance of the model. Alternative sub-process 2 can then be run and results compared.

SIMPROCESS defines a single default sub-process when a Process is created. Renaming the sub-process to something more meaningful for the model is accomplished by:

1. Selecting it from the Alternative Sub-Processes list on the Process dialog.

2. Clicking Edit to modify the sub-process definition.

3. Highlighting the existing name and typing over it. For this example, call the sub-process Main.

4. Click on OK.

The new name appears in the Alternative Sub-Processes list and becomes the sub-process.

More sub-processes may be added to the Process by clicking on Add and naming the new sub-process. Activate a different sub-process by selecting it from the Alternative Sub-processes list.

Sub-processes may be deleted with the Remove command button and copied using the Copy button.

Click on OK when the Process is defined.

Adding Detail to a Process

Once a Process is defined, define the Activities and Processes that make up the Process.

Right-click on the Process icon and choose Descend to open the layout of the currently active sub-process

A blank layout is shown, except for two Pads: an input Pad on the left and an output Pad on the right. If the output Pad is not visible, scroll to the right.

These Pads connect any Processes and Activities at this level of the sub-process to the Activities and Processes at the next higher level. Once the input and output Pad are connected by Connectors, Entities flow from level to level.

Activities (and Processes) may be added within the sub-process to detail the tasks being performed.

NOTE: Make sure the Input and Output Pads are connected on all sub-processes. If this is not done, Entities will have no path to follow across the Process. Entities entering the Process will never emerge again.

Simulation Setup

Two steps are needed before running a simulation:

· Set the run time parameters for the simulation. This could include start and end dates or number of times to repeat the simulation.

· Set animation parameters.

Run Settings

Select Simulate from the SIMPROCESS menu and then click on Run Settings... to set run time options.

Setting the Start and End Dates

The values chosen for the Start and End fields determine how long the simulation runs, in calendar time. A simulated month of processing can be specified as:

Start: 1/1/2007 00:00:00:000:000:000

End: 2/1/2007 00:00:00:000:000:000

This indicates a starting date of January 1, 2007, at midnight, and an end date of February 1, 2007, at midnight. The simulation terminates as soon as the clock strikes midnight at the end of January 31. The calendar button next to each date field can be used to set the date for that field. The calendar button causes a graphical calendar to appear. The date selected on the graphical calendar populates the appropriate date field.

A time must be entered or the hours, minutes, seconds, nanoseconds, microseconds, and milliseconds fields default to zero.

NOTE

Run Dates and the Real Calendar

Both entity generation schedules and resource downtime schedules can be based on a day of the week. SIMPROCESS calculates the day of the week, as well as the month, year, and time of day, at any moment in a simulation. It maps the simulation dates to the real calendar. For example, in 2007 the year begins on a Monday.

Setting the Simulation Time Unit

SIMPROCESS allows the Simulation Time Unit to be set, which is the time unit of the simulation clock. The simulation clock must maintain a constant time unit. The default is Hours. Even though each individual time unit can be different, those times are converted to the time unit of the simulation clock. Also, this is important for reducing rounding errors. If the primary delays in the model are in seconds or less, the time unit of the simulation clock should be set to Seconds or less. Converting a delay in nanoseconds (or even seconds) to hours could result in rounding errors, whereas converting a delay in nanoseconds to seconds or less would not.

Animation Settings

Show Clock turns the simulation time clock on or off while the simulation is running.

Show Counts. If Show Counts is turned on, each Activity or Process will display a number above its icon.

· Generate Activities show the number of Entities generated.

· Dispose Activities show how many Entities have been disposed.

· All other Activities and Processes show how many entities are in that Process or Activity.

Show Entities turns the display of Entities on or off during the animation. Showing Entities assists with visualizing the workflow.

Update Dynamic Labels turns the display of dynamic labels on or off during the animation.

Animation Speed. Changes the Animation Speed during the simulation. The fastest value is 100, and the default is 20. A smaller value is better while debugging the model.

Running a Simulation

Start the simulation running, either by clicking the run icon on the tool bar, or selecting Simulate from the SIMPROCESS menu bar, followed by Run.

Before starting the simulation, SIMPROCESS does two things:

1. Prompts for saving the latest changes to the model

2. Checks the model for errors.

SIMPROCESS issues informational messages and aborts the simulation if errors are found.

Choose Verify Model from the Simulate menu before running to check the model for errors before running a simulation.

Running a Simulation with Model Parameters

If the model has User-defined Attributes which were selected as Model Parameters, when the simulation run is started, SIMPROCESS will prompt for initial values for those Model Parameters.

The Model Parameters are displayed in a table. The column under Parameter gives the name of the User-defined Attribute. The Value column shows the value the attribute will have at the start of the simulation run.

To change the value of a Model Parameter, select it in the table. The Description of the selected parameter will be displayed below the table along with its default value and the mode of its value (integer, real, etc.)

The next step is to enter the desired value of the Model Parameter in the Value field. If Reset is pressed, the selected Model Parameter will return to its default value. The Reset All button, under the Help button, will set the value of all the Model Parameters back to their defaults.

Creating Model Parameters from User-defined Attributes is covered in Chapter 10, "Customizing a Model with Attributes and Expressions," beginning on page 237.

Model Parameters can be changed during a simulation run by selecting Change Model Parameters from the Simulate menu.

Allowable Actions During a Simulation

While a simulation is running, a Process can be descended into to view Entity movement within the Process hierarchy. Descending into a Process is done by using Descend on the View menu, clicking the down arrow on the tool bar, right clicking on a Process and choosing Descend, or by double-clicking on a Process.

Choose Ascend on the View menu to ascend to a higher level of the model hierarchy. Click the up arrow on the tool bar, right click on blank area and choose Ascend, or double-click on any blank area of the model layout. Choose Go To Top instead of Ascend to ascend to the top level of a model.

The Simulate option on the menu bar causes the following options to occur:

· Pause the simulation

· Resume simulation after a pause

· Stop the simulation before its scheduled end

· Click on Animation Settings to change animation options. The simulation pauses while this is being done. Changing the animation options using the tool bar does not pause the simulation.

Double click on an Activity icon to bring up its properties dialog. However, any changes made will not be reflected in the running simulation.

Animation can be recorded for playback after the simulation ends. (See "Post Simulation Animation" on page 172.)

Standard Report

After the simulation run has completed, the Standard Report may be displayed to view output statistics for the model. From the Report menu bar, choose Display Standard Report.

This will open the Display Standard Report dialog. In the Report Replications list box (if the model ran for multiple replications), select an individual Replication, the Average of All Replications run, or the Sum of All Replications run. Typically, the report of interest will be the Average of All Replications report. Calculate Confidence Intervals is activated if the Average of All Replications report is selected, which allows selection of 90%, 95%, or 99% confidence intervals for each performance measure. Select to view the Standard Report with a Text Editor (Wordpad by default) or with a Spread Sheet and press the Display Report button to open the report.

See Chapter 8, "Output Reports," beginning on page 185 for more detail on the Standard Report.

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