This
section summarizes the measurements of the REVOLUTION
Powder Analyzer. These measurements are
completed during the following four testing methods:
As
seen above, the digital camera captures
images of the powder in the rotating drum at the
desired speed.The
software then calculates the potential energy (power)
of the powder for every image.This power average is the average
potential energy of the powder
during the specified test run.
The three images displayed above represent an avalanche cycle from the initial
powder image, peak and the completed avalanche.
The
power slope is the slope of the line from the
accumulated individual powers of each
avalanche. The Red
line represents the power slope in this graph.
For
the avalanche median and power calculations, the
software calculates the change (or delta)
from the beginning height of the avalanche to
the ending height of the avalanche. The sum of a
list of these avalanche values, divided by the
total number of avalanches in the test. In
addition, the software provides the standard
deviation of this measurement. Standard
deviation is the measure of the variability of
the normal distribution of this avalanche power
graph. This variance is calculated as the
average squared deviation of each number from
its calculated avalanche power average.
The
sum of the time of each of these avalanches,
divided by the total number of avalanches in the
test. In addition, the software provides the standard deviation of this
measurement. Standard
deviation is the measure of the variability of
the normal distribution of this avalanche time
measurement. This variance is calculated
as the average squared deviation of each number
from its calculated avalanche time average.
Estimating
the Hurst exponent for this avalanche power set
provides a measure of whether the analysis is a
purely random or has underlying trends.
Processes such as avalanche size that we might
initially assume are purely random sometimes
turn out to exhibit long memory processes.
If the avalanche Hurst exponent is
0.5 < H < 1.0, the avalanches
have a long memory process or persistent
behavior. In other words, the avalanche
power is exhibiting a long term trend by either
continually increasing or decreasing. If the avalanche Hurst exponent
is 0.5, the avalanches exhibit
completely random behavior. If the
avalanche Hurst exponent is 0 < H < 0.5,
the avalanches exhibit anti-persistent behavior. In other words,
the avalanche with a larger avalanche power will
most likely be followed by an avalanche with a
smaller avalanche power.
The
software collects the angle of the powder at the
maximum power prior to the start
of the power avalanche occurrence. This
measurement is the average value for all the
avalanche angles. In our avalanche cycle
example displayed above, the avalanche angle
would be calculated at the peak cycle.
The
software collects the angle of the powder at the
minimum power of the powder at the end of the avalanche occurrence. This
measurement is the average value for of all the
rest angles. In our avalanche cycle example
displayed above, the rest angle would be
calculated at the change of power cycle.
The volume for the initial powder sample is
measured. For every digital image
taken, the software measures the volume of the sample.
The software then calculates the average volume of the powder
during the test. During the fluidization
test, the software measures the change of the sample
volume during the test.
The
surface fractal is the fractal dimension of the
surface of the powder and provides an indication of how
rough the powder surface is. The
measurement is made after each avalanche to
determine how the powder reorganizes itself. If
the powder forms a smooth even surface, the
surface fractal will be near one. If the
surface is rough and jagged, the surface fractal
will be greater than one. For applications
requiring an even distribution of powders, such as
die filling, the closer the surface fractal is
to one the better the powder will perform.
Surface
Linearity is the linear correlation value for
the surface of the powder after an avalanche. This measurement is an indication of
how linear the surface of the powder is after an
avalanche. For applications requiring even
distribution of powders, such as die filling, the
more linear the surface of the powder is the
better the powder will perform.
The volume for the initial powder sample
is
measured. For every digital image
taken, the software measures the volume of the
sample while the sample is being fluidized. The
software calculates the average volume of the
powder during the fluidization test.
The
height for the initial powder sample is
measured. For every digital image
taken, the software measures the height of the
sample while the sample is being fluidized. The
software calculates the average height of the
powder during the fluidization test.
