Selection of Descriptors for Particle Shape Characterization

2003 ◽  
Vol 20 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Mark L. Hentschel ◽  
Neil W. Page
Keyword(s):  
Particle Shape ◽  
Shape Characterization ◽  
Selection Of Descriptors ◽  
Selection Of

scholarly journals Selection of Descriptors in a Morphological Characteristics Considered In Cassava Accessions By Means Of Multivariate Techniques

2014 ◽  
Vol 7 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Sandra Domingos João Afonso ◽  
◽  
Carlos Alberto da Silva Ledo ◽  
Ricardo Franco Cunha Moreira ◽  
Sebastião de Oliveira e Silva ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Multivariate Techniques ◽  
Selection Of Descriptors ◽  
Selection Of

scholarly journals On the microwave optical properties of randomly oriented ice hydrometeors

2014 ◽  
Vol 7 (12) ◽  
pp. 12873-12927
Author(s):  
P. Eriksson ◽  
M. Jamali ◽  
J. Mendrok ◽  
S. A. Buehler
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Particle Shape ◽  
Reference Data ◽  
Microwave Remote Sensing ◽  
Particle Orientation ◽  
Maximum Dimension ◽  
Single Observation ◽  
Single Temperature ◽  
Selection Of

Abstract. Microwave remote sensing is important for observing the mass of ice hydrometeors. One of the main error sources of microwave ice mass retrievals is that approximations around the shape of the particles are unavoidable. One common approach to represent particles of irregular shape is the soft particle approximation (SPA). We show that it is possible to define a SPA that mimics mean optical particles of available reference data over narrow frequency ranges, considering a single observation technique at the time, but SPA does not work in a broader context. Most critically, the required air fraction varies with frequency and application, as well as with particle size. In addition, the air fraction matching established density parameterisations results in far too soft particles, at least for frequencies above 90 GHz. That is, alternatives to SPA must be found. One alternative was recently presented by Geer and Baordo (2014). They used a sub-set of the same reference data and simply selected as "shape model" the particle type giving the best overall agreement with observations. We present a way to perform the same selection of a representative particle shape, but without involving assumptions on particle size distribution and actual ice mass contents. Only an assumption on the occurrence frequency of different particle shapes is still required. Our analysis leads to the same selection of representative shape as found by Geer and Baordo (2014). In addition, we show that the selected particle shape has the desired properties also at higher frequencies as well as for radar applications. Finally, we demonstrate that in this context the assumption on particle shape is likely less critical when using mass equivalent diameter to characterise particle size, compared to using maximum dimension, but a better understanding of the variability of size distributions is required to fully characterise the advantage. Further advancements on these subjects are presently difficult to achieve due to a lack of reference data. One main problem is that most available databases of precalculated optical properties assume completely random particle orientation, while for certain conditions a horizontal alignment is expected. In addition, the only database covering frequencies above 340 GHz has a poor representation of absorption as it is based on outdated refractive index data, as well as only covering particles having a maximum dimension below 2 mm and a single temperature.

Particle Shape Characterization from Packing Density

2018 ◽  
pp. 15-22
Author(s):  
Keishi Gotoh ◽  
Mitsuyoshi Kumamoto ◽  
T. P. Meloy
Keyword(s):  
Packing Density ◽  
Particle Shape ◽  
Shape Characterization
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