Overview

The purpose of this technote is to briefly review the features and use of the Post Calculation Processor available in WaterGEMS and WaterCAD. Additional information can be found in the Help section for WaterGEMS or WaterCAD.

Background

The Post Calculation Processor is a tool that allows you to run simple statistical analyses on results obtained from computing an extended period simulation (EPS). These results can be displayed in the element properties or FlexTables as User Data Extensions.

Post Calculation Processor Properties

The Post Calculation Processor is a simple dialog consisting of a few fields, including the start and stop times, the statistic you wish to compute, the WaterGEMS property field the analysis will be run off of, the output property (or User Data Extension), and the operation type.

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There are also Delete and Select From Drawing icons, as well as the Calculate button that will run the statistical analysis.

Opening Post Calculation Properties

The Post Calculation Processor can be accessed by going to the Analysis pulldown and selecting Post Calculation Processor. It can also be open from the Post Calculation Processor icon in the toolbar.

After selection this, a small Select dialog will open.

This common tool in WaterGEMS that allows you to choose the elements that will be included in the analysis. The default setting for the dialog is that the Add icon is selected. With this, you can click on any element in the model for inclusion in the analysis. It will highlight in red on the drawing pane. Conversely, you can also remove selections by choosing the Remove icon. The Select dialog also allows for you to choose a selection based on a polygon or query. Unless you are selecting only a few elements, the Query icon may be the most efficient as it allows you to select an already-created Selection Set of elements.

Note: For more information on Selection Sets, please review the Help topic on that subject.

Once you have selected the elements in the drawing, choose the green checkmark icon. The Post Calculation Processor dialog will then open.

Note: You can select the elements for analysis later if you wish. To do this, choose the green checkmark icon without making a selection on the drawing pane. The Post Calculation Processor will then open. You can then select the “Select from Drawing” icon in the Post Calculation Processor, which will open the Select dialog described above.

User Data Extensions

As mentioned earlier, the Post Calculation Processor requires the analysis results to be saved into an existing User Data Extension (UDX). The UDX can either be created ahead of time or from the Post Calculation Processor. The UDX dialog can be accessed directly by going to Tools > User Data Extensions.

Note: You can also open the UDX dialog directly from the Post Calculation Processor dialog by select the ellipsis (…) button next to the Output Property field.

To create a UDX, highlight the element and select the New icon. The section on the right will fill in with default data. More than likely the results of the statistical analysis of the Post Calculation Processor will be a “real” number, or a non-integer. Because of this, change the Data Type to “Real”. When this is completed, the Units section will appear. Enter the appropriate Dimension, Storage Unit, and Numeric Formatter for analysis you will be conducting. You should also change the label to something recognizable for the analysis. Once you have done, select Okay.

Note: Once you select Okay, some fields such as Data Type, Dimension, and Storage Unit cannot be changed or edited.

Running a Statistical Analysis

Once the User Data Extension is created, you are ready to run a statistical analysis. The Post Calculation Processor is capable of simple statistical analyses, such as means, standard deviations, and sums. A complete list is available by selecting the Statistical Type dropdown menu.

Note: For more complicated calculations, the latest release of WaterGEMS and WaterCAD has the capability of creating formula-based User Data Extensions. For more information on this, see the Help menu or the Creating Formula-Based User Data Extensions technote.

To run the analysis, first make sure that you have selected elements in the model. A list will appear in the bottom window of the Post Calculation Processor. Next, choose the start and stop time for the analysis. Then, select the Statistic Type.

Next, select the Result Property. This is the element property you analyzing. The dropdown will contain all of the Results properties for the element type selected. After making this selection, choose the UDX you created from the Output Property dropdown. Lastly, select the Operation. The most common will be “Set”, though you can also choose to add, subtract, multiply, or divide.

Finally, click the Calculate button. The program will run the calculation and a dialog will appear stating that it is complete and display the number of elements affected.

Viewing Results

Since the results are saved into a user data extension, you can view the results in either the element properties or the FlexTables.

To see the results in the properties, doubleclick on one of the elements that were analyzed to open the Properties dialog. You will find the name of your UDX under the section “User Defined”.

To see the results in the FlexTables, open the element FlexTable (through View > FlexTables, for instance). With the FlexTable open, select the Edit icon. Scroll through the list on the left to find the UDX field. The list is in alphabetical order. Select the Add button and it now appear in the list on the right. Click Okay to return to the FlexTable. The statistical analysis results should now be available.

This data is also available for results presentation in graphs and data tables.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Water and Wastewater Forum

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

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