Cloud Of Spherical Particles Research Articles

PMD Distribution Measurement by an OTDR With Polarimetry Considering Depolarization of Backscattered Waves

In previous studies of polarization-mode-dispersion (PMD) distribution measurement by an optical time-domain reflectometer with polarimetry (p-OTDR), scatterers were assumed to be clouds of nonspherical particles in a fiber. However, the pulsewidth dependence of the degree of polarization (DOP) could not be explained by the assumption of nonspherical backscattering alone. In this paper, it is reported that the p-OTDR waveforms were fitted well by modified Mueller matrices under the assumptions of scattering by cloud of spherical particles and a reduction in the DOP due to the interference of the backscattered waves with the phase fluctuation. A PMD distribution measurement is demonstrated based on the p-OTDR Jones matrix eigenvalue method with the assumption of slowly varying PMD along the fiber length, and the regeneration of the PMD distribution of test fibers fabricated by splicing constituent fibers with known PMDs was successful. Surprisingly, the regenerated PMD distribution along the fiber length shows a linear accumulation of constituent fiber PMD in the short range of 6 km. The reverse-direction measurements show a reasonable regeneration of what is assumed to be a linear accumulation along the fiber length, which strongly suggests that the PMD distribution along the fiber shows a linear accumulation rather than a root-length accumulation in relatively short fibers with smaller PMD

Radiative Transfer With Dependent Scattering by Particles: Part 1—Theoretical Investigation

Dependent radiation scattering for which the independent scattering theory fails to predict the scattering properties is important in analyzing radiative transfer in packed and fluidized beds. In this paper the dependent scattering properties have been derived assuming the Rayleigh–Debye scattering approximation for two cases: two identical spheres and a cloud of spherical particles. The two-sphere calculated results compare well with the exact solutions in the literature, giving confidence in the present analytical approach. The gas model and packed-sphere model have been employed to calculate dependent scattering properties for a cloud of particles of small and large particle volume fraction, respectively. The calculated dependent scattering efficiencies for a cloud of particles are smaller than the independent scattering efficiencies and decrease with increasing particle volume fraction. A regime map for independent and dependent scattering has been constructed and compared with existing empirical criteria.