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MERCURY Scientific Inc

 

Overview

Applications

Mechanics

Analysis

 

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This section summarizes the measurements of the REVOLUTION Powder Analyzer.  These measurements are completed during the following four testing methods:

Flowability

Granulation

Fluidization

Caking

Power Average

Building of Power

Peak Power

Change of Power

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.

Power Average and Power Slope

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.

Avalanche Median

The avalanche median is avalanche time at the power median (50% point) of all of the measured avalanches.   

Avalanche Power

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.

Avalanche Time

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.

Avalanche Hurst Exponent

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. 

Avalanche Angle

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.

Rest Angle

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.

Sample Volume

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.   

Surface Fractal

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

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.

Fluidized Volume

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.  

Fluidized Height

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.  

Fluidized Rate

This is a graphical analysis of the fluidized volume versus angular velocity of the sample during the fluidization testing.

Settling Rate

This is the amount of time required for the powder to return to reach a stable volume after the powder has been fluidized.

 

Copyright of Mercury Scientific Inc      Revised March 2008     All rights reserved.