نتایج جستجو برای: grains

تعداد نتایج: 27038  

2005
M. C. Wyatt

This paper considers the distribution of dust which originates in the break-up of planetesimals that are trapped in resonance with a planet. The effect of radiation pressure on small dust grains causes their orbits and so their spatial distribution to be significantly different to that of the parent planetesimals which previous work has shown to be clumpy. It is shown that there are three disti...

1999
Eberhard Grün Markus Landgraf

Identification by the Ulysses spacecraft of interstellar grains inside the planetary system provides a new window for the study of diffuse interstellar matter. Dust particles observed by Ulysses and confirmed by Galileo are more massive (≥ 10−13 g) than the ’classical’ interstellar grains. Even bigger grains (≈ 10−7 g) were observed in form of interstellar meteors. We analyze the consequences o...

Journal: :Physical review letters 2011
F Pacheco-Vázquez J C Ruiz-Suárez

Impact experiments in granular media are usually performed with solid projectiles that do not fragment at all. Contrastingly, we study here the morphology produced by the impact of spherical granular projectiles whose structure is utterly lost after collision. Simple and complex craters are observed, depending on the packing fraction of the balls. Their diameters D and depths z are analyzed as ...

2008
Larry L. Berger

Nutrient composition of commercial corn grain appears to have changed little in the last 10 to 15 years. Although the data for sorghum grain and barley are more limited, no dramatic changes in nutrient composition were apparent. Flaking corn appears to reduce the crude protein concentrations, perhaps because water used for starch gelatinization is not released during drying. Harvesting and stor...

2002
H. R. Piehler A. D. Rollett

Meso-scale surface roughening evolution in 6022-T4 Al sheets was investigated using plane-strain tension. Formation of grain-scale hills and valleys and their relation to the morphologies and corresponding orientations of surface grains after deformation were examined experimentally. These observations were analyzed using various approaches based on the Schmid and Taylor crystal plasticity mode...

2017
Jia En Neo Iain A. Brownlee

Previous epidemiological evidence suggests that habitual consumption of whole grains is associated with reduction of disease risk. While wholegrain food consumption appears to be increasing in Singapore, it is still low, with more infrequent consumption noted in younger Singaporeans. Therefore, the primary objective of this study is to determine the knowledge of whole grains and barriers to con...

1998
H. A. Makse H. J. Herrmann

– We study segregation and stratification of mixtures of grains differing in size, shape and material properties poured into two-dimensional silos using a microscopic lattice model for surface flows of grains. The model incorporates the dissipation of energy in collisions between rolling and static grains and an energy barrier describing the geometrical asperities of the grains. We study the ph...

2001
David E. Harker Steven J. Desch

Silicate dust grains in the interstellar medium are known to be mostly amorphous, yet crystalline silicate grains have been observed in many long-period comets and in protoplanetary disks. Annealing of amorphous silicate grains into crystalline grains requires temperatures > ∼ 1000K, but exposure of dust grains in comets to such high temperatures is incompatible with the generally low temperatu...

1998
Anja C. Andersen

We present here the first infrared spectra of meteoritic SiC grains. The mid-infrared transmission spectra of meteoritic SiC grains isolated from the Murchison meteorite were measured in the wavelength range 2.5–16.5 μm, in order to make available the optical properties of presolar SiC grains. These grains are most likely stellar condensates with an origin predominately in carbon stars. Measure...

2003
Huirong Yan

Interstellar dust grains exhibit complex dynamics which is essential for understanding many key interstellar processes that involve dust, including grain alignment, grain growth, grain shattering etc. Grain rotational and translational motions are affected not only by gaseous collisions, but also by interactions with ions, photons, magnetic fields etc. Some of those interactions, e.g. interacti...

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