202,367 research outputs found

    Electromagnetic Scattering and Statistic Analysis of Clutter from Oil Contaminated Sea Surface

    Get PDF
    In order to investigate the electromagnetic (EM) scattering characteristics of the three dimensional sea surface contaminated by oil, a rigorous numerical method multilevel fast multipole algorithm (MLFMA) is developed to preciously calculate the electromagnetic backscatter from the two-layered oil contaminated sea surface. Illumination window and resistive window are combined together to depress the edge current induced by artificial truncation of the sea surface. By using this combination, the numerical method can get a high efficiency at a less computation cost. The differences between backscatters from clean sea and oil contaminated sea are investigated with respect to various incident angles and sea states. Also, the distribution of the sea clutter is examined for the oil-spilled cases in this paper

    Effect of Dependent Scattering on Light Absorption in Highly Scattering Random Media

    Full text link
    The approximate nature of radiative transfer equation (RTE) leads to a bunch of considerations on the effect of "dependent scattering" in random media, especially particulate media composed of discrete scatterers, in the last a few decades, which usually indicates those deviations RTE (combined with ISA) lead to from experimental and exact numerical results due to electromagnetic wave interference. Here we theoretically and numerically demonstrate the effect of dependent scattering on absorption in disordered media consisting of highly scattering scatterers. By making comparison between the independent scattering approximation-radiative transfer equation (ISA-RTE) and the full-wave coupled dipole method (CDM), we find that deviations between the two methods increase as scatterer density in the media increases. The discrepancy also grows with optical thickness. To quantitatively take dependent scattering effect into account, we develop a theoretical model using quasi-crystalline approximation (QCA) to derive dependent-scattering corrected radiative properties, based on the path-integral diagrammatic technique in multiple scattering theory. The model results in a more reasonable agreement with numerical simulations. The present work has profound implications for the coherent scattering physics in random media with absorption, correctly modeling light absorptance in random media and interpreting the experimental observations in various applications for random media such as solar energy concentration, micro/nanofluids, structural color generation, etc.Comment: 30 pages, 8 figures, submitte

    Discovery and Testimony of Unretained Experts: Creating a Clear and Equitable Standard to Govern Compliance With Subpoenas

    Get PDF
    Hearing impairment is known to be one of the most frequent sensory impairments. This condition is known to be a hidden disorder which is under recognised and under treated all around the world. The World Health Organisation (WHO) estimates suggest that there are over 275 million people with hearing impairment and 80% of them living in low and middle income countries. Moreover, the estimates suggest that incidence and prevalence of hearing loss and also the number of people with hearing loss accessing services varies considerably across countries. This rises the need for health promotion (or public awareness campaigns) directed to increase awareness and education of hearing loss and hearing healthcare. This paper provides brief discussion on ‘Stories and storytelling’, ‘Cross-culture and cross-cultural communication’ and ‘Health promotion and cultural sensitivity’. The central focus of this paper is to highlight the applications of storytelling in different cultural context in health promotion, particularly to hearing loss public awareness campaigns
    corecore