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ECN Analysis Software - Quick Start Guide

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2.0 ECN Analysis Software - Quick Start Guide

 

ECN analysis 1.0 calculates the time evolution  of noise resistance, low-frequency noise impedance, charge and frequency of corrosion events based on the user selected parameters (see "Selection of processing parameters"). In this section, the algorithms used in the software are described. ECN Analysis 1.0 requires an input file of suitable format. In order to generate the input file from your data file you must use ECN Converter 1.0. See "ECN Converter Software" >> "Quick Start Guide" for instructions on how to generate a suitable input file for ECN Analysis 1.0.

 

2.1 Processing Your first file

 

 

Open a standard ECN file containing corrosion potential and corrosion current data.

 

Use File-> Open or press the Speed Button   openbutton

 

 

 

The software responds with a file open dialog , Select your ECN file.

 

openfile

 

Figure 23.0  ECN file open dialog box, ECN Analysis Version 1.0 .

 

A typical ECN file  is shown below. The first column must contain time values, the second column the corrosion current in (amperes) and the third column the corrosion potential ( in millivolts).

 

typical ECN file

 

Figure 24.0 A typical Electrochemical Noise (ECN) File.

 

 

If the file read is successful, the software displays the following messages with the size of allocated memory and record length.

   

 

The time record window for Both Potential and Current are updated with the newly read content from the ECN file.

 

potandcurrent

 

Figure 25.0 The time record  tab  of ECN analysis version 1.0

 

 

Setting the processing parameters.

 

Go to  Preference Menu' -> Processing Preference.

 

The software responds with a separate dialog Box and prompts the user to enter the processing parameters.The user enter the various parameters like length of FFT, the type of FFT window to be used etc.

 

pref1

 

 

Figure 26.0  The Preferences window of ECN Analysis version 1.0

 

 

Sampling Interval / s

 

The sampling rate originally used in your experiment needs to entered on the sampling rate box, the time column of the input file will be ignored.

 

Spectra  average

 

The software calculates noise impedance from power spectral densities of potential and current. The noise impedance spectrum is usually noisy and to improve readability a number of impedance spectra from adjacent segments can be used to obtain an averaged impedance spectrum.The number of spectra for the calculation can be entered here.

 

Points Average for Low-Frequency Limit

 

Low-frequency impedance and low-frequency limits of potential and current power spectral densities (required to estimate charge and frequency of corrosion events) are calculated by averaging some points in the low frequency regions of the impedance spectrum. The number of points (and therefore the frequency range) used to extract low-frequency limits can be entered here.

 

Stern Geary Coefficient / V

 

The Stern-Geary coefficient is required to obtain accurate estimation of charge and frequency of corrosion events. Make sure that you enter the appropriate Stern-Geary coefficient for the material/environment combination that you are studying.

 

Skip Iterations Between Saved Spectra

 

 

This software allows you to save complete Potential and Current power spectral density  spectra periodically. This parameters indicates how often complete spectra are saved can be entered here. The lower the number, the higher the number of spectra saved.  The software gives asks the user, prior to starting the processing, if spectra need to be saved. If 'NO 'is selected, the Skip Interactions Between Saved Spectra parameter has no effect. Generally, it is not required to save the spectra periodically and a  'NO' should be selected prior to starting  the processing.

 

Segments Overlap %

 

The distance between the first point of one segment and the first point of the following segment is specified in Segment Overlap %. The default value is 95%. High overlap produce more accurate results and enables to use more heavy time-averaging without compromising time resolution, but increases the processing time. For very long dataset it is suggested to  use a smaller  overlap percentage.

 

To Process your file either go to  the menu item ' Processing -> Start '  or use the speed button processbutton

 

 

The software starts to process the file and the processing your selected file. The progress can be monitored on the Time Record tab. The time associated to the segment that is being currently processed is highlighted with a  diamond shape on the potential and current time records. The Progress is also visible on th the Progress bar.

 

 

What all I can explore during and after Processing ?

 

The software allows you to visualize  the potential and current segments that are currently being processed in the ' Processing ' tab. In the top part the current segment and the potential segment are shown. The software  removes any  DC drift ( or trend )  in the time record by linear curve fitting and displays the result in the central graphs.  The bottom graphs shows the Power Spectral densities calculated using FFT method, which is obtained from the potential and current segments.

 

 

process1

 

Figure 27.0 The Processing tab of ECN analysis 1.0. This tab shows a segment of potential, current before and after trend removal. The two bottom two graphs are the power spectral densities of current and potential respectively.

 

 

The  third tab (PSD) shows the noise impedance calculated from these 2 PSD's. The graph on the bottom is the Average impedance obtained after averaging few impedance spectra specified by ' No of spectra to average' in the preference window. The fourth tab ( Resistance / Charge / Frequency ) shows Noise impedance , Noise resistance, Charge and the Frequency of events.

 

process3

 

 

Figure 28.0 The Results tab of ECN Analysis version 1.0. It provides low-frequency Noise impedance , Noise Resistance ,Average charge and Frequency of corrosion events.

 

Saving your first result ( ECN / Other )

 

This software allows you to save the results and specifically the Low-Frequency Impedance , Noise Resistance , Charge and frequency of Events as a function of experimental time. It uses two formats.

 

To Save your results go to Save Menu item and use  any of the 2 options or use the speed buttons provided.

 

 

savebutton

 

 

(a). ECN format

 

This format is used by this software for comparison purpose. If you want to compare different results obtained with ECN Analysis 1.0, you must save the results using this method. The comparison can be carried out by going into  'Comparison menu'. Upto 3 files can be compared .

 

saveother

 

(b). Other format

 

This format allows the user to save results in text file format. If the user want to load the results or to manipulate the data with third-part software this option must be selected

 

 

 

 

Comparing  Results

 

ECN Analysis 1.0  allows comparison of Impedance (obtained by FFT Method) , Resistance (obtained by Variance), Charge and the Frequency of corrosion events by loading multiple ECN  results files in the comparison table.  Generally, only files generated using the same processing parameters should be compared. ECN Analysis 1.0 will issue a warning message, if two files processed using different parameters are compared, but  it allows to continue with comparison. Only files stored in ECN format can be compared using this method ( Please see 'Saving your first Result ( ECN) ' ).

 

 

To compare results go to  ' Compare' menu.

 

compare1

 

 

1. Open your first file for comparison

 

If no files have been loaded , only 'Open Main'  will be  active in the menu. Once the main file  is loaded, the software allows to open another file. The software displays a file open dialog box.If the file has not been generated by ECN Analysis 1.0, an error message will appear and the file will not be loaded. If the file is loaded successfully, the  graphs of Impedance, Resistance, Charge and frequency of events are displayed.

 

 

errorecn noterror

Figure 29 : If user tries to open non ECN file the software             Figure 30: If Software finds a Signature of ECN type it shows this

                displays an Error message .                                                               message box.

 

 

fileone

 

Figure 31. The  Comparison tab of ECN Analyser 1.0  Upto 3 results can be compared using this functionality.

 

2. Open Your Second file for comparison

 

 

Once an ECN file is in memory the software allows to open the second file , this can be done using  'compare' -> file 2 .

 

 

comapre2

 

On successful loading, the software updates the graphs with the content of the second file.The various parameters can be compared at this time.

 

comparefiles

Figure 32. The  Comparison tab of ECN Analyser 1.0  Upto 3 results can be compared using this functionality.

 

3. Opening the third file for comparison

 

The third file can be loaded with a similar procedure by going into   'compare '-> file3.

 

4. Clearing the graphs

 

The content of file2 or file3 can be cleared individually. ( For this use either 'Compare'->clear2 or 'Compare'->clear3 ). To clear the main file you have to clear all the graphs. This can be done by going into 'compare' ->clear all.

 

There is a small 'print' button provided at the bottom left corner of each charts in the ECN Analysis  1.0. The user can print any of the charts at any stages of ECN analysis. When the button is  pressed a print preview screen appears and the user can select  the printer, set up the margins, eliminate the  background etc. The  complete process of previewing, setting up the printer etc... are  illustrated in the following  figures.

 

Printing

 

There is a small 'print' button provided at the bottom left corner of all the charts in the ECN Analysis  version 1.0. The user can print any of the charts in the ECN analysis version 1.0 software by using this  button.   When this button is  pressed  the user is provided with a print preview screen.

 

print1

 

 

figure 33.0 The user can print any of the graphs at any stages of processing. Margins, orientation ,background etc.. can be changed here.

 

1. Setting up the Printer

 

User can select the  set up the printer  by pressing the 'Setup' button in the chart preview window. Printer properties , paper source selection, paper size , orientation of the printing etc... can be selected in 'Print Setup' dialog box.

 

 

 

print2

 

 

Figure 34.0  Printer setup can be done by pressing the 'Setup' button in the chart preview window. Printer Properties can be selected by pressing the

'Properties' button in the Print Setup dialog box.

 

2. Changing the printer Properties

 

Print quality, Paper size, print effects, and other printer properties can be done in the Printer properties dialog box.

 

print3

 

Figure 35.0 paper source, paper size selection, Print effects etc... can be selected here (the steps to be followed are highlighted using red circles and arrows ).

 

Editing Charts

 

The charts can be edited by using the small ' Edit' button on the bottom left corner of every charts. This temporarily modifies the chart properties like  axis colour , axis type ( like 2D or 3D graphs) , axis labels graph labels ,graph legends, scale ( ex: logarithmic / linear ) etc...

 

An example is given in figure 36. Here the axis labels are removed using 'axis visible' property.

 

editchart

 

Figure 36.0 Here, the chart edit facility is used to remove both the axis of the chart by uncheking the 'axis visible' property.

 

 

 

 

Saving and Plotting the Spectra

 

The software provides an option for the user to he spectra  periodically. The option is provided to the user at the beginning of the processing. The software will ask the user  whenever  the software starts a new electrochemical noise analysis. It is not always required to save the complete spectra, doing so can result in a large spectra file. The parameter  'skip iterations between saved spectra' determines how often the complete spectra will be saved to the disk.

fig1

Fig 33.0  Whenever a new Data file is processed, the software asks the user weather if spectra must be saved.

 

menu31    

Fig 34.0 Saving the complete spectrum is not required always and can result in a large data file.

 

Table below shows how  a typical ' spectra_file'  is organized

 

'Nth' Record

  X axis ( in log)

potential PSD

Current PSD

Impedance PSD

1126

-3.01029996        

0.52261167

0.00000002

4172.30476987

1126

-2.70926996

0.29134762

0.00000001

4156.83706831

1126

-2.53317870

0.06467640

0.00000000

6102.40065220

1126

-2.40823997

0.03039187

0.00000000

6702.12785726

-

-

-

-

-

1126

-0.30103000

0.00000009

0.00000000

8180.12650179

1177        

-3.01029996

0.61943963

0.00000001

4172.30476987

1177

-2.70926996

0.30128671

0.00000001

4156.83706831

1177

-2.53317870

0.05226266

0.00000000

6102.40065220

Note :  ( Total number of values depends on FFT Length, for Ex. if FFT length is 1024 there will 1024 values for N th record)

Table 2.0 :  ECN analysis software uses the above shown format for a spectra file.