# Model 1c - Time Instants for Start Events

## Goals of the lesson

• Knowing what a recurrent time instant is and how it is being set up

## How-to

Model 1c accords with Model 1a. The only difference is that we use Recurring Time Instants to determine the start event’s inter-arrival time.

Figure 1. Model 1c - Time Instants for Start Events / IYOPRO-Link

### Approach

To setup the Recurrent Time Instant for this diagram do the following:

1. Make sure, you selected the Simulation option from the Property Set drop-down-box.

2. Click the Timer Start Event

3. Click the button right of the empty field of the Inter-arrival Time option under the Must-Have-Properties

4. The Time Editor shows up. Now select Time Instant from the drop-down-box in the top left corner of the Time Editor.

5. In the drop-down-down-box right to the caption "1. Recurrence" select Hourly, which means that every hour exactly one time instant will be scheduled (respectively the time instant will recur every hour), which will then trigger the start event.

6. Now select an end (or stop) criteria. We will leave it to Open end, which signalizes the simulation, that the time instant will recur every hour until the simulation has stopped. But we could also specify a stop criteria

1. by amount: The time instant will stop recurring after the given number

2. by time: The time instant will stop recurring after the given time is exceeded

The picture below depicts the Time Editor in Recurring Time Instant mode after we configured it.

 The Time Editor offers you a consecutive recurrence when you select one of the latter stop criteria.
Figure 2. IYOPRO’s Time Editor in Time Instant Perspective

## Report

See below for the run configuration, which we set up to receive the report statistics from below.

### Run configuration

• Stochastic Seed: 12345

• Simulation start date: 1/1/2014 12:00:00 a.m.

• Simulation stop time: 24

• Simulation stop time unit: Hours

### Report statistics

• Did you notice that this report’s are equal to Model 1a’s report? (Except for the event details).

• Though we shortened the total simulation time to 24 hours (instead of 48 hours at Model 1a), the results are the same

• This bases on the shorter inter-arrival time of Model 1c’s start event

• Model 1c’s start event has a mean inter-arrival time of exactly 1 hour

• This is the value we assigned to it by the calendar-based time instant which recurs every hour

• Therefore number of processes is the same as in Model 1a

Figure 3. Event details