American Association for Aerosol Research - Abstract Submission

AAAR 39th Annual Conference
October 18 - October 22, 2021

Virtual Conference

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Comparing Multiple Types of Machine Learning for Characterizing TEM Images of Soot

TIMOTHY SIPKENS, Hamed Nikookar, Max Frei, Frank Einar Kruis, Steven Rogak, University of British Columbia

     Abstract Number: 452
     Working Group: Instrumentation and Methods

Abstract
TEM imaging is a mainstay in the characterization of aerosols, like soot. One of the largest barriers to population-wide statistics is the often-labor-intensive manual approach to image analysis. This work examines a series of machine learning approaches to distinguishing soot from the background in TEM images, including (1) unsupervised k-means clustering, (2) a convolutional neural network, and (3) trainable Weka segmentation, via the Fiji image analysis package. Classifications are compared to a largely-manual, in-house method where a user-specified threshold is applied in local regions of the image. Methods show a marked improvement over existing classifiers across a range of images, with over 99% classified pixel accuracy and only a small number of falsely identified aggregates. We also present sensitivities of a range of automated primary particle sizing techniques to the chosen classifier, which is a step towards fully automated analysis of soot TEM images. We conclude by examining the relationship between primary particle size and projected-area equivalent diameter of soot.