BSA Flow Software Installation and User's Guide - CSI

5.14 Moments
5.14.1 Data from the Moments object
The Moments object is used to compute time averages of measured
quantities (One-Time statistics), such as mean and RMS on the basis of
velocity samples, particle diameter or analog input data. Parent objects are
Import velocity files, BSA Application, Coincidence and Transform. If
Transform is the parent object, moments are calculated on the basis of
orthogonal velocities u, v and w, and otherwise calculations are performed
on the basis of velocities from LDA1, LDA2 and LDA3.
The possible output parameters from the Moments object are:
• Position
• Date_Time
• Count
• Data rate
• Validation
• Mean
• RMS
• MeanConf
• RMSConf
• Skewness
• Flatness
• Cross moments
• Anode current
• Analog Monitor
• AD Mean
• AD RMS
These parameters are explained below.
Position: the x, y and z co-ordinates of the measurement position
Date_Time: the date and time of the start of data acquisition in that position
Count: the number of samples in that position
Data rate: the data rate of data in that position. The data rate is calculated as
numSamples/(endAT - startAT).
Validation: the mean validation rate in that position based on the BSA’s
validation readings
For the parameters Mean, RMS, skewness, flatness and cross moments,
the formulas used are shown in Table 5-4, using u and v as inputs. The
inputs may also be analog data or particle diameter. Skewness is sometimes
referred to as Kurtosis.
5-72 BSA Flow Software: Project explorer objects