Flow measurement data analysis

This standalone software is installed with the control software and allows analysis of flow measurement data recorded with the flow measurement workflow.

The software tries to fit the increase of fluorescent intensity measured in the workflow for each pressure greater than 0mbar with a simple linear regression model and then plots the calculated slopes to allow for a qualitative assessment of the flow through a probe over time.

When the software is started, it directly prompts you to open a file saved during a flow measurement.

Software overview

The software is split into three main areas:

Data plot

The data plot displays the intensity of the whole duration of the measurement, segmented into phases where pressure was idle (white background) and phases where the pressure was greater than 0mbar (green background, pressure indicated at the top). In case color saturation was reached during a non-idle phase, it is shaded red instead to indicate that the intensity values measured may not be meaningful.
The green line drawn above the data in each pressure segment shows the fitted regression line.

If you are not satisfied with the automatic fitting, this green line can be adjusted by moving the mouse over the pressure segment and then dragging either square appearing at each of the line’s end points.

The slope and intercept corresponding to the corrected regression line will automatically be updated in the flow rate analysis table. Right-click anywhere within the same pressure segment to reset the line to automatic fitting.

Zooming

Use the and buttons or hold down the Ctrl key while scrolling with the mouse wheel to zoom the plot in or out.

Flow rate analysis

The table in the bottom left area contains the result of each fitting. The diagram to the right of the table contains an entry (displayed as a point) for each calculated slope (flow rate) of a fitted line, grouped by the name given to the pressure pulse. Individual points can be excluded from the slope computation by unchecking the checkbox in the Include column.
Data points from different repetitions of the measurement are plotted with different colors.

The data in the table can be selected and copied to the clipboard:

• Shift- or Ctrl-click to select multiple lines
• Ctrl+A selects all
• Ctrl+C copies the entries

Change of flow rate over time

The calculated flow rate per pressure is fitted again with a simple linear regression model for each repetition of the measurement. The result is shown in the table and plot in the bottom right.
The table contains the fitted slope, intercept and the standard error (±) of the slope and the data can be copied in the same way as the flow rate per pressure table.

Adjusting fitting parameters

The software assumes that each pressure pulse starts with a linear increase of fluorescent intensity up to a certain point where dispersion prevents further concentration of fluorescent liquid in the area of the flow measurement. To find this point, the software iteratively fits data as long as the coefficient of determination r² remains above a certain threshold. This threshold is called min r² and can be adjusted individually for each pressure segment either below the data plot or in the bottom left table.