Thursday, October 13, 2005

GTViewer's Gas Valve Isolation Application

The Gas Valve Isolation Application has always been used as demonstration of GTViewer’s Network Tracing capabilities. This application allows the user to select a piece of gas main (where a leak has occurred), then the application traces the gas network in all directions looking for valves that would need to be closed to isolate the leak from the rest of the network. Also, the application determines which customers will be affected by closing the valve.

Early versions of this application simply searched for the valves that bounded the leak. While this was a flashy demo, it did not look beyond the immediate bounding valves to see if the network on the other side dead-ends (in which case, the valve doesn’t need to be closed and the customers on the other side of the valve also need to be included in the affected list). The current version of the Gas Valve Isolation Application does check the network on the other side of the bounding value until it finds a source; thus, a more useful result is provided.

The screenshot below shows the Gas Valve Isolation Application:

Once activated, the application waits for the users to select a gas main segment to start the analysis from. Once selected, the network is traced (using the GT/Trace components). The user can optionally fit the trace results while the trace runs (using the Fit while Tracing option); this option causes the trace to run slower, but shows exactly how the trace is progressing. The Gas Valve Isolation Application looks not only for valves that must be closed to isolate the leak, but it also gathers a list of all customers who will be affected by the isolation. The customer list is shown at the top of the form (by address) and the valve list is shown at the bottom. Clicking on either a customer or a valve will locate on that item in the view. The trace results are persistent, so locating on the customer or valve does not clear the results. The Fit Results button will always take you back to the overall view of the results. A Copy Customer Window button is provided to copy the list of customers to the Windows clipboard. These results can then be pasted in Excel or any other application. A Copy Valve Window is also provided to copy the Valve results to the Windows clipboard.

Another feature of the Gas Valve Isolation Application is that it takes into account that a user’s data might not model the source for the gas network. In this case, you can set a limit as to how far it should trace until it assumes that a source is at the other end. The Limit options allow the user to set various lengths or the Next Valve.

The screenshot below shows the isolated main in Red and the Green traces back to the source. The two valves that need to be closed in this example are pointed to with the Magenta Arrows. The Arrows are also Data Monitor items and show additional information as a tooltip when the cursor hovers over them.

The Gas Valve Isolation Application has evolved from a flashy demo to show off GTViewer’s tracing to a very useful analysis tool capable of proving important information in the field and on demand. It also shows off one more example of GTViewer’s success as a GIS application development platform.

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