User's guide chapter 3 section 5 & 6

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3.5 – Entity Arrivals

Arrival connections define how entities enter the system to begin processing. Entity arrivals are defined by connecting an entity object to an activity or storage object and then entering any defining information in the properties dialog for the connection. Multiple arrival connections can be created from an entity to one or more activities or storages.

Entity Arrivals

Common Tabs

There are two common tabs on the properties dialog for arrivals: Action and Name. These tabs are explained in this section first followed by a description of each type of arrival.

Action

Assign custom behavior to a model when entities arrive in the model. In addition to the arrival information set in the General tab of the arrival properties dialog, assignment statements and IF…THEN statements can reference user-defined entity attributes as well as predefined attributes and variables.

Properties dialog entity arrivals action tab ProcessModel software

Action logic is processed at the instant the entity is created but before entering any activity. To learn more about Action Logic, see Section 3.11, Action Logic.

Name

The Name tab (shown below) allows you to define route names when you are linking hierarchical models. All arrival connections have a Name tab in their properties dialog. For more information, see Chapter 7, Hierarchical Modeling.

Properties dialog entity arrivals name tab ProcessModel software

Connection name This name is used when mapping connections between different charts (main model and submodel). For hierarchical modeling only. See “Connection Naming” in Chapter 7.3.3.

Entity Arrival Types

Following is a description of each type of arrival that can be defined. To change the arrival type, select the desired type from the Type option under the General tab of the Arrival properties dialog. The following types are available:

• Continuous
• Daily Pattern
• Ordered
• Periodic
• Scheduled

3.5.1 – Continuous

A continuous arrival causes entities to continuously feed the connected activity whenever processing capacity is available at the activity; any activity input queue is ignored. This type of an arrival should only connect to activities and requires no other information to be defined.

Properties dialog entity arrivals continuous ProcessModel software

Important information to be aware of You should be aware of the following operating constraints when using the Continuous arrival:

• DO NOT bring other arrivals into the same activity or storage to which the Continuous arrival is attached.
• Since the input queue is ignored when using the Continuous arrival, any batching activity set to occur before the activity will be ignored as well.

3.5.2 – Daily Pattern

A daily pattern arrival shows the rate at which entities arrive for different time periods during the day. Arrivals are assumed to occur randomly within each period. The pattern for each day of the week can be different from the others.

Daily pattern arrivals graph

Important information to be aware of If a shift file has been defined for the activity where entities arrive, it is a good idea to synchronize the arrival periods with the activity schedule.

Properties dialog entity arrivals daily pattern ProcessModel software

Properties dialog entity arrivals daily pattern ProcessModel software

As displayed after the pattern for Monday has been defined

Day The list of days of the week. A pattern may be defined for each day.

Start – End, Quantity The list of period entries showing the start time, end time, and quantity of entities to arrive during that period for the day currently selected.

Copy day Button to copy a day’s pattern in order to paste it later on another day. Prevents tedium of entering the same periods for each day of the week that has the same arrival pattern.

Paste day Once a day has been copied, the Paste button becomes active and lists the name of the day that will be copied in the button itself. Select another day in the Day list and press the button to paste the pattern into the new day.

New Creates a new period entry in the Start – End, Quantity list with default times and quantity. The order of the new entry in the list will automatically be adjusted to maintain a chronological list.

Delete Removes an arrival period from the list.

Start time The start time edit field for the currently selected period.

End time The end time edit field for the currently selected period.

Quantity The quantity edit field for the currently selected period. Any valid expression may be used.

Important information to be aware of Time entries for a Daily Pattern many not overlap (Correct example: Monday 8:00-9:00, 9:00-10:00. Incorrect example: Monday 8:00-9:00, 8:30-9:30 — these time slots overlap).

How To – Define a daily pattern

1. Click on the Define Pattern button to display the Daily Pattern dialog.

2. Click the New button to create a new entry in the pattern dialog. This creates the Monday 8:00am – 9:00am, 1 default entry. (The quantity and times may be changed as desired.)

3. Repeat step 2 for each time period to be defined in which arrivals occur.

4. Once a particular day’s pattern has been defined, you can copy the pattern to another day by selecting the defined day, clicking on the Copy day button, then selecting the day to which the pattern will be copied and clicking the Paste button. (The name of the weekday appears on the Paste button, so you will know which day is being copied.)

A Note About Time

When you use the Daily Pattern arrival or Scheduled Arrival, you must understand that statistics, especially resource statistics, may be affected due to the way the clock works in ProcessModel. Each ProcessModel simulation begins at 12:00 a.m. (midnight) on Monday morning of the first week. Therefore, Daily Pattern or Scheduled arrivals may skew statistical results, especially with regard to resource and input and output queue utilization. The solution is the use of Shifts in conjunction with your Daily Pattern or Scheduled arrivals. For more information see Schedules—Shifts & Breaks.

3.5.3 – Ordered

An ordered arrival is used in connection with an order signal connection to place an order for more entities to arrive (see Section 3.8, Order Signals).

Properties dialog entity arrivals ordered ProcessModel software

Properties dialog entity arrivals ordered ProcessModel software

Lead Time This is the time required for the entities to arrive once an order is placed. Any expression excluding attributes is valid.

3.5.4 – Periodic

A periodic arrival causes entities to arrive at repeating time intervals. It is also useful for initializing inventory levels at the beginning of the simulation. This is done by entering a time of zero (0) in the Repeat Every field.

Properties dialog entity arrivals periodic ProcessModel software

Repeat every The time between arrivals. Any expression excluding attributes is valid. A time value of zero (0) will cause only one entry for this arrival.

Quantity per arrival The number of entities that arrive after each time interval. Any expression excluding attributes is valid.

First time The time (relative to the beginning of the simulation) that the first arrival should occur. Use a time of zero (0) to initialize the model with entities at the beginning of the simulation.

 The maximum amount of time that can be entered in the First Time field of a Periodic arrival is 35,791 hours. If a larger value is entered, the arrival will occur as the simulation starts rather than at the designated time.

3.5.5 – Scheduled

A scheduled arrival causes a quantity of entities to arrive at a storage or activity at set times such as appointments or incoming shipments. Multiple scheduled arrivals for the same time occur in the order in which they are defined.

Properties dialog entity arrivals scheduled ProcessModel software