Customized Acoustical-Analysis Programs continued...

New Approach Speeds Analysis
To speed this process, the company hired On-line Digital Technologies, Inc. to write a custom AE analysis program. Rather than writing an entire program from scratch, On-line Digital opted to build the application on Origin 5.0, a Windows-based technical graphics and data analysis software package from Microcal Software, Inc., located in Northampton, Massachusetts. This software package provided several crucial advantages that made it ideally suited for this application. For example, Origin utilizes an extremely powerful programming language, called LabTalk, which provides access to virtually every function in the program. In addition, Origin provides an extensive range of graphing capabilities, allowing the user to adjust virtually any parameter of the graph simply by clicking on it with a mouse.

Figure 3- Event Rate contour plot of extracted data for events in cluster at location 2674.

Working with Origin application programmers, On-line Digital researchers developed a LabTalk program that largely automates the AE analysis process. Custom Origin templates and tools provide the user interface and manage the process. A user starts the process by filling out a customer worksheet. This window asks for basic information about the project such as the customer's name, the date, the unit being tested, temperature ranges, and what pre-filtering was done to the data.

Figure 4- Event Rate contour plot, Location vs Time, with Plant Parameters overplotted. Shows entire pipe section under test. (Note high activity indication near location 2300 Inches resulting from small pressure excursion at ~ 1100 minutes.)

The user then proceeds through the analysis process by pushing buttons within the software to select the next step. When the program is given the command to import the raw data, it performs the necessary scaling of temperature and pressure data automatically. The first analysis screen the user selects is a three-part display of events plotted against location, the exact location of the waveguides, and amplitude versus location. Next, the user activates the cluster analysis graphic display, then with Origin's enlarger tool, the user can expand those areas on the screen dynamically. A click of another button extracts the data of interest to a separate cluster worksheet and allows the user to perform a cluster analysis on it. The graphic presentation includes the minimum, maximum, average, and standard deviation of signal features, such as rise times, amplitudes, frequencies, which the user can then evaluate against the criteria mentioned above. The entire process now only takes but a few minutes.