8,885 research outputs found
Computer program determines thermal environment and temperature history of lunar orbiting space vehicles
Program computes the thermal environment of a spacecraft in a lunar orbit. The quantities determined include the incident flux /solar and lunar emitted radiation/, total radiation absorbed by a surface, and the resulting surface temperature as a function of time and orbital position
Force distributions and force chains in random stiff fiber networks
We study the elasticity of random stiff fiber networks. The elastic response
of the fibers is characterized by a central force stretching stiffness as well
as a bending stiffness that acts transverse to the fiber contour. Previous
studies have shown that this model displays an anomalous elastic regime where
the stretching mode is fully frozen out and the elastic energy is completely
dominated by the bending mode. We demonstrate by simulations and scaling
arguments that, in contrast to the bending dominated \emph{elastic energy}, the
equally important \emph{elastic forces} are to a large extent stretching
dominated. By characterizing these forces on microscopic, mesoscopic and
macroscopic scales we find two mechanisms of how forces are transmitted in the
network. While forces smaller than a threshold are effectively balanced
by a homogeneous background medium, forces larger than are found to be
heterogeneously distributed throughout the sample, giving rise to highly
localized force-chains known from granular media.Comment: 7 pages, 7 figures, final version as publishe
Rheological instability in a simple shear thickening model
We study the strain response to steady imposed stress in a spatially
homogeneous, scalar model for shear thickening, in which the local rate of
yielding \Gamma(l) of mesoscopic `elastic elements' is not monotonic in the
local strain l. Despite this, the macroscopic, steady-state flow curve (stress
vs. strain rate) is monotonic. However, for a broad class of \Gamma(l), the
response to steady stress is not in fact steady flow, but spontaneous
oscillation. We discuss this finding in relation to other theoretical and
experimental flow instabilities. Within the parameter ranges we studied, the
model does not exhibit rheo-chaos.Comment: 8 pages, 3 figs. Minor corrections made. To appear in Euro. Phys.
Let
Book review and critical dialogue about The Making of Monolingual Japan: Language Ideology and Japanese Modernity (Heinrich, 2012)
Head and Tsurii take Heinrich’s book, The Making of Monolingual Japan, as a starting point for a critical dialogue in which they make connections between language ideology, native speakerism, and learner autonomy. Heinrich focuses on the historical development of the modern Japanese language after the Meiji Restoration in the late 19th century. He highlights the link between modernist language ideology of “one nation, one language,” which originated in 18th-century Germany, and the Meiji era drive to create a unified Japanese language. Although not explicitly referring to an alternative multilingual ideology, Heinrich suggests that inequalities in modern Japan
result from the monolingual language policy and that “power-based ideologies should be replaced with ideologies based on cultural liberty and solidarity” (p. 4). In their dialogue, Tsurii and Head discuss connections between monolingual ideology and native-speakerism. Finally they explore how this awareness impacts their practices as teachers who would like to foster learner autonomy
The Dormant Foreign Affairs Power: Constitutional Implications for State and Local Investment Restrictions Impacting Foreign Countries
State and local pension funds have billions of dollars invested in global markets, and often use these assets to pressure foreign nations to change their human rights policies. Social investing practices and other non-social investment decisions impacting foreign nations may be impermissible incursions into the federal government\u27s exclusive power over foreign policy under the Dormant Foreign Affairs Power, an implied constitutional restriction on state activity. This Note argues that in this era of global markets, a blanket prohibition against criticism of foreign nations does not allow states to fulfill their investment obligations. This Note calls for a flexible test to determine the constitutionality of state action—a test that considers the federal government\u27s need for uniformity in foreign policy with the need of state governments to be global economic actors
Chemical differentiation on one-plate planets: Predictions and geologic observations for Venus
Recent studies have examined the partial melting of planetary interiors on one-plate planets and the implications for the formation and evolution of basaltic crust and the complementary residual mantle layer. In contrast to the Earth, where the crust and residual layer move laterally and are returned to the interior following subduction, one-plate planets such as Venus are characterized by vertical accretion of the crust and residual layer. The residual mantle layer is depleted and compositionally buoyant, being less dense than undepleted mantle due to its reduced Fe/Mg and dense Al-bearing minerals; its melting temperature is also increased. As the crust and depleted mantle layer grow vertically during the thermal evolution of the planet, several stages develop. As a step in the investigation and testing of these theoretical treatments of crustal development on Venus, we investigate the predictions deriving from two of these stages (a stable thick crust and depleted layer, and a thick unstable depleted layer) and compare these to geologic and geophysical observations, speculating on how these might be interpreted in the context of the vertical crustal accretion models. In each case, we conclude with an outline of further tests and observations of these models
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