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Digital in-line holography is a versatile method to obtain lens-less images of small particles, such as aerosol particles, ranging from several to over one hundred microns in size. It has been shown theoretically, and verified by measurement, that a particle’s extinction cross section can also be obtained from a digital hologram. The process involves a straightforward integration, but if noise is present it fails to give accurate results. Here we present a method to reduce the noise in measured holograms of single particles for the purpose of rendering the cross-section estimation more effective. The method involves masking the complex-valued particle image-amplitude obtained from a noisy hologram followed by a Fresnel transformation to generate a new noise-reduced hologram. Examples are given at two wavelengths, 440 nm and 1040 nm, where the cross section is obtained for a micro-sphere particle and several non-spherical particles approximately 50 microns in size.
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SOOT MASS ESTIMATION FROM ELECTRICAL CAPACITANCE TOMOGRAPHY IMAGING FOR A DIESEL PARTICULATE FILTER
The Electrical capacitance tomography (ECT) method has recently been adapted to obtain tomographic images of the cross section of a diesel particulate filter (DPF). However, a soot mass estimation algorithm is still needed to translate the ECT image pixel data to obtain soot load in the DPF. In this paper, we propose an estimation method to quantify the soot load in a DPF through an inverse algorithm that uses the ECT images commonly generated by a back-projection algorithm. The grayscale pixel data generated from ECT is used in a matrix equation to estimate the permittivity distribution of the cross section of the DPF. Since these permittivity data has direct correlation with the soot mass present inside the DPF, a permittivity to soot mass distribution relationship is established first. A numerical estimation algorithm is then developed to compute the soot mass accounting for the mass distribution across the cross-section of the DPF as well as the dimension of the DPF along the exhaust flow direction. Experimental data has been used to validate the proposed soot estimation algorithm which compared the estimated values with the actual measured soot mass. The estimated soot mass for various soot load amounts were found to correlate reasonably well with the measured soot masses in those cases.
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- Award ID(s):
- 1633426
- PAR ID:
- 10196679
- Date Published:
- Journal Name:
- Proceedings of the ASME International Mechanical Engineering Congress and Exposition
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/IMECE2019-11295
