Accession Number : ADB392010


Title :   Radiative Transfer Model for Contaminated Rough Surfaces


Descriptive Note : Final technical rept. Jan-Sep 2012


Corporate Author : ARMY EDGEWOOD CHEMICAL BIOLOGICAL CENTER APG MD


Personal Author(s) : Ben-David, Avishai ; Davidson, Charles E


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/b392010.pdf


Report Date : Feb 2013


Pagination or Media Count : 64


Abstract : We studied the radiative transfer and reflectance of potassium chlorate and ammonium nitrate contaminated surfaces in mid-wavelength and long-wavelength infrared for detection. Our framework is a combination of theoretical-based radiative transfer (conservation of energy), an empirical approximation for reflectance of rough surfaces, and empirical modifications of the target absorption coefficients to account for effects of deposition morphology. Our model is formulated such that two-way attenuation (by absorption) through the target material is the primary source for spectral features to appear in the observed radiance. We obtained excellent or good results for lab measurements of potassium chlorate on most aluminum surfaces; however, ammonium nitrate on painted aluminum was more complicated due to spectral correlation between compound and surface. Most of the signal energy came from the specular direction, hence, the ability of the model to explain off-specular reflection is of lower importance. Good specificity was demonstrated against lab data (low probability to misidentify potassium chlorate as ammonium nitrate and vice versa). We also observed moderate success on field data.


Descriptors :   *CONTAMINATION , *RADIATIVE TRANSFER , *SURFACE ROUGHNESS , ABSORPTION COEFFICIENTS , AMMONIUM NITRATE , CHLORATES , INFRARED RADIATION , LONG WAVELENGTHS , POTASSIUM , REFLECTANCE , SCATTERING


Subject Categories : Physical Chemistry
      Mechanics
      Thermodynamics


Distribution Statement : APPROVED FOR PUBLIC RELEASE