An experimental investigation into modeling solids friction for fluidized dense-phase pneumatic transport of powders

Results are presented of an ongoing investigation into modeling friction in fiuidized dense-phase pneumatic transport of bulk solids. Many popular modeling methods of the solids friction use the dimen- sionless solids loading ratio and Froude number. When evaluated under proper scale-up conditions of pipe diameter and length, many of these models have resulted in significant inaccuracy. A technique for modeling solids friction has been developed using a new combination of dimensionless numbers, volu- metric loading ratio and the ratio of particle free settling velocity to superficial conveying air velocity, to replace the solids loading ratio and Froude number. The models developed using the new formalism were evaluated for accuracy and stability under significant scale-up conditions for four different prod- ucts conveyed through four different test rigs （subject to diameter and length scale-up conditions）. The new model considerably improves predictions compared with those obtained using the existing model, especially in the dense-phase region. Whereas the latter yields absolute average relative errors varying between 10% and 86%, the former yielded results with errors from 4% to 20% for a wide range of scale-up conditions. This represents a more reliable and narrower range of prediction that is suitable for industrial scale-up requirements.

Compound solitons in fiber Bragg grating

Single soliton and compound solitons are described by coupled-mode equation. It is noted that three parameters, which are dimensionless group velocity, normalized frequency, and grating strength, influence formed solitons by emulation. The novel designs of parallel and serial multi-grating are advanced, and the compound solitons formed from parallel multi-grating are linear superposition; the compound solitons formed from serial multi-grating are nonlinear superposition, and finally two general formulae are obtained. Furthermore, it is theoretically shown that the compound grating solitons are prominent and flexible signals in optical communication.

Beach morphodynamic characteristics and classifications on the straight coastal sectors in the west Guangdong

Currently beach morphodynamic classification is the most important foundation to conduct associated coastal geomorphological studies.This paper carried out beach morphodynamic classifications for 12 straight beaches on headland-bay coasts based on field survey and evaluated the applicability of the most widely used dimensional fall velocity parameter(Ω)and relative tidal range parameter(RTR).One reflective,five intermediate and six non-barred dissipative beaches were visually classified and sand size seemed to be a key factor to differentiate these beaches.The studied beaches were in relatively low wave energy environments(Hs<1 m)and the absolute deep-water wave energy level of P0=3 KWm-1 was supposed to a critical threshold to characterize the applicability of theΩand RTR parameters.These two morphodynamic parameters were applicable for the beaches with P0>3 KWm-1 and MSR<2 m.It was found that the model of the traditional winter-and-summer profiles was not applicable in the study area in despite of distinct wave seasonality.The studied beaches were more possible to hover around a limited range due to relatively low background wave environments and variability without considering typhoon impacts,which needs further research on actual breaker wave conditions and beach morphodynamic type responses to typhoon events.