Analysis of the velocity field of granular hopper flow

We report the analysis of radial characteristics of the flow of granular material through a conical hopper. The discharge is simulated for various orifice sizes and hopper opening angles. Velocity profiles are measured along two radial lines from the hopper cone vertex: along the main axis of the cone and along its wall. An approximate power law dependence on the distance from the orifice is observed for both profiles, although differences between them can be noted. In order to quantify these differences, we propose a Local Mass Flow index that is a promising tool in the direction of a more reliable classification of the flow regimes in hoppers

On the origin of unusual transport properties observed in densely packed polycrystalline CaAl_{2}

A possible origin of unusual temperature behavior of transport coefficients observed in densely packed polycrystalline CaAl_{2} compound [M. Ausloos et al., J. Appl. Phys. 96, 7338 (2004)] is discussed, including a power-like dependence of resistivity with $\rho \propto T^{-3/4}$ and N-like form of the thermopower. All these features are found to be in good agreement with the Shklovskii-Efros localization scenario assuming polaron-mediated hopping processes controlled by the Debye energy

Produtividade de forragem de gramíneas e leguminosas em pastagens puras e consorciadas no Acre.

A formação de ecossistemas homogêneos de pastagens cultivadas na Amazônia, com a predominância de uma espécie de gramínea forrageira, tem favorecido a ocorrência de pragas e doenças que afetam a produtividade e a sustentabilidade dos sistemas de produção pecuários tradicionais. Este estudo teve o objetivo de avaliar a produtividade e a taxa de acúmulo de forragem de gramíneas e leguminosas em pastagens formadas com as gramíneas Panicum maximum cv. Colonião, Tobiatã, Massai e BRA-006670 e as leguminosas amnedoim forrageiro (Arachis pintoiu BRA-031143 e Arachis glabrata cv. Arbrook) e puerária (Pueraria phaseoloides) em estandes puros e consorciados.bitstream/item/76387/1/CPAF-AC-BOL.-PESQ.-33-01.pd

Irreversibility line and low-field grain-boundary pinning in electron-doped superconducting thin films

AC magnetic susceptibilities of electron-doped Pr_{1.85}Ce_{0.15}CuO_4 (PCCO) and Sm_{1.85}Ce_{0.15}CuO_4 (SCCO) granular thin films have been measured as a function of temperature and magnetic-field strength. Depending on the level of homogeneity of our films, two different types of the irreversibility line (IL) defined as the intergrain-loss peak temperature in the imaginary part of susceptibility have been found. The obtained results are described via the critical-state model taking into account the low-field grain-boundary pinning. The extracted pinning-force densities in more granular SCCO films turn out to be four times larger than their counterparts in less granular PCCO films