Using Time Series Elements

Time Series elements are a type of input element that provide a very flexible and powerful way to input external time histories of data into GoldSim (i.e., a table showing how a variable changes as a function of time).

You can use a Time Series element to input the predefined histories of things like interest rates, commodity prices, temperature, rainfall rates, sales rates, cash flows, or the condition (reliability, strength) of a machine or a material. A Time Series element represents an exogenous (external) “driver” that can directly or indirectly influence the dynamic behavior of the system being modeled.

Note: Time Series elements are for time series that are known in advance of the simulation. If you want to generate random (stochastic) histories during your simulation, you should use a History Generator element instead.

To define a Time Series element, you input a set of time series records (i.e., a table of times and values) and specify what the data represent (e.g., instantaneously measured values at specified times). Note that the time values in the input time series do not have to coincide with the model’s timesteps.

You then specify what the output of the element should be (e.g., the average value of the variable over each timestep). GoldSim then carries out the appropriate calculations in order to convert the input data into the specified output.

For example, if the input data is specified as a series of instantaneous values, GoldSim interpolates between the time series records to produce the output time series.

Note: A number of advanced options are initially hidden by the More button.

1. Define the type (scalar, vector, or matrix; value or discrete change) and units for the time series;

2. Specify the source for the input data (e.g., defined directly, imported from spreadsheet);

3. Specify what the time series input represents (e.g., instantaneous values at specific times, constant values over specified intervals);

4. Define the time series itself (if specified directly) or the location of the data source (if imported); and

5. Specify the output types to be computed for the element (e.g., instantaneous values at each timestep, average values over a timestep).

Each of these steps, as well as some example files and advanced options, are described in the topics below.

Note: In addition to inputting pre-defined histories, one of the advanced options for a Time Series element is to use it to record (and subsequently play back) a history computed by another GoldSim element.

Several files are provided within the TimeSeries subfolder of the General Examples folder of your GoldSim directory (accessed by selecting File | Open Example... from the main menu) that include examples on the use of Time Series elements.