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To configure optimised ordering, begin by choosing Edit » Ordering Network Costs... or click Configure Ordering on the Ordering toolbar and choose Network Costs.... This opens the Network costs dialog (Figure 31).
Figure
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1. Network costs (summary)
Creating cost functions
By default, Source creates one default cost function for each Storage node in your model. You can add, remove or rename cost functions using a combination of the Add and Remove buttons, and the contextual menu that pops up when you right-click on the list of cost functions. A common pattern is to add cost functions that are applicable to various periods throughout the year. The finest level of granularity supported by Source is a cost function applicable to a single month.
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Use the Storage Break Points tab (Figure 42) to design cost functions. Begin by using the Storage Cost Function pop-up menu to select a cost function that you defined in the Cost Functions list in theSummary tab. Next, select the storage that should be associated with this cost function.
Figure
42. Network Costs (Storage Break Points)
| Note |
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| Although you can define storage breakpoints for storage A in terms of storage B, you should avoid doing so because it can lead to infeasible solutions. |
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The result of the design intention is shown in Figure 53. Note that, in the absence of any inflows that replenish the storages, the X-axis can also be interpreted as expressing time.
Figure
53. Carryover Arc Costs vs Storage Volume
Applying cost functions
You apply cost functions in the Storage Targets tab (Figure 64). Each storage in your model is represented by a row in this table. The remaining columns contain pop-up menus where you can connect an appropriate cost function to a selected storage for a particular month.
Figure
64. Network costs (Storage targets)
You can also import storage targets from a .CSV file. The format of the file is shown in Table 3. Note that the column ordering in the .CSV file does not match the display in Figure 6.
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You can specify the number of shortfall arcs that are generated for each of the demand nodes using the Number of Shortfall Arcs drop down menu (Figure 75). The default number is 4.
Figure
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5. Network
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costs (Demand
...
priorities)
You can control the order in which shortfalls are satisfied. The Priority column in Figure 75 shows which demand component of the model has will receive water via its shortfall arcs.
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- Select the active scenario in the Project Hierarchy (Project Explorer);
- Locate the Arc-Node Network entry in the Model Parameters list (also Project Explorer) and enable it for recording;
- Run the scenario; and
- In the Values column of the Recording Manager (Complex time series, summary), locate and open View Multiple Supply Path Setup. The window will be similar to Figure 96.
Figure 96 is a work in process so most of the labels are inaccurate. The graph provides a measure of computational complexity (iterations to solve) at each time-step. Note that the peaks are clipped to the value of the Maximum Iterations parameter in Figure 1this dialog.
Figure
96. Inspecting the generated arc-node model
Clicking any point in the time line causes a textual representation of the arc-node model for that time-step to be displayed in the upper part of the window. The text can be selected and placed on the clipboard for re-use.
Note that it is beyond the scope of this guide to explain the format of the arc-node model dump.
Inspecting an arc-node network (advanced)
It is also possible to visualise the arc-node networks that are generated by Source. However, you will first need to download and install a third-party software package called Graphviz. The home page for this application is:
Choose the current stable release in preference to any development snapshots. Consult your Windows system administrator if you need help installing Graphviz.
To enable debugging and visualisation support in Source:
- Choose Edit » Ordering Algorithm...;
- Enable Export iterations;
- If your model operates over a large number of time-steps, you may wish to restrict the date-range for which arc-node output is produced using the Start and End date controls in this dialog; and
- Click OK.
Next, run your model. Enabling Export iterations creates a folder on your Desktop with a name in the pattern:
MspNetworkOutput-yyyy-mm-dd
At the end of a run, this folder will contain three files per time-step:
- A visual representation (.DOT) of the arc-node network suitable for display in Graphviz;
- A textual representation of the arc-node network; and
- A textual representation of the test case for that time-step.
| Info | ||
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| Note: You should avoid double-clicking files with a .DOT extension. You may find that files with a .DOT extension will launch Microsoft Word rather than Graphviz. |
To visualise an arc-node network for a given time-step:
- Use the Windows Start menu to launch Gvedit, which is part of Graphviz;
- Choose File » Open and select the .DOT file of interest. Gvedit will respond by opening a textual representation of the arc-node network as shown in the central window in Figure 7; and
- Click the Run button on the Gvedit toolbar (Figure 7).
Figure 7. Gvedit (opening an arc-node network)
Graphviz always generates a graphical representation of your arc-node network in two forms. One is displayed on your screen and the other is saved as a file. By default, the version saved as a file is in .GIF format but you can change this using the Output File Type pop-up menu in Figure 8. Note that Graphviz can also generate high-resolution vector-based representations such as .SVG.
By default, the file is saved in the same folder as the original .DOT file. You can change this by clicking the ellipsis button (...) to the right of the Output File Name field in Figure 8.
Figure 8. Graphviz settings dialog
Once the settings have been configured to your requirements, click OK. Figure 9 is an excerpt from an arc-node network diagram produced by Graphviz. The elements inside the blue rectangle correspond with a Splitter node in the original Source schematic.
Figure 9. NetLP arc-node network for Splitter node
