6,916 research outputs found
Design optimization of high-performance electrodynamic actuators for use in a cryogenically cooled telescope
An analysis and optimization of a mirror-actuator system for large excursion/high-frequency chopping is developed. The results of this analysis, combined with laboratory measurements of a prototype actuator operating at cryogenic temperatures, allow performance predictions to be made for a real system utilizing this technology
O aleitamento interrompido como prática para antecipar o aparecimento do estro em porcas.
bitstream/item/59090/1/CUsersPiazzonDocuments105.pd
Anisotropic elastic theory of preloaded granular media
A macroscopic elastic description of stresses in static, preloaded granular
media is derived systematically from the microscopic elasticity of individual
inter-grain contacts. The assumed preloaded state and friction at contacts
ensure that the network of inter-grain contacts is not altered by small
perturbations. The texture of this network, set by the preparation of the
system, is encoded in second and fourth order fabric tensors. A small
perturbation generates both normal and tangential inter-grain forces, the
latter causing grains to reorient. This reorientation response and the
incremental stress are expressed in terms of the macroscopic strain.Comment: 7 pages, 2 figures. Accepted version. [email protected]
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Influência da adubação follar a base de água de xisto e combinada com cálcio e boro na produção de morangos cvs camarosa e camino real.
Teores de compostos fitoquímicos em morangueiro cultivados com adubações complementares sólida e foliar.
Low field hysteresis in disordered ferromagnets
We analyze low field hysteresis close to the demagnetized state in disordered
ferromagnets using the zero temperature random-field Ising model. We solve the
demagnetization process exactly in one dimension and derive the Rayleigh law of
hysteresis. The initial susceptibility a and the hysteretic coefficient b
display a peak as a function of the disorder width. This behavior is confirmed
by numerical simulations d=2,3 showing that in limit of weak disorder
demagnetization is not possible and the Rayleigh law is not defined. These
results are in agreement with experimental observations on nanocrystalline
magnetic materials.Comment: Extended version, 18 pages, 5 figures, to appear in Phys. Rev.
Curvature Corrections to Dynamics of Domain Walls
The most usual procedure for deriving curvature corrections to effective
actions for topological defects is subjected to a critical reappraisal. A
logically unjustified step (leading to overdetermination) is identified and
rectified, taking the standard domain wall case as an illustrative example.
Using the appropriately corrected procedure, we obtain a new exact (analytic)
expression for the corresponding effective action contribution of quadratic
order in the wall width, in terms of the intrinsic Ricci scalar and the
extrinsic curvature scalar . The result is proportional to with the
coefficient given by . The resulting form of the ensuing dynamical
equations is obtained in terms of the second fundamental form and the
Dalembertian of its trace, K. It is argued that this does not invalidate the
physical conclusions obtained from the "zero rigidity" ansatz used in
previous work.Comment: 19 pages plain TeX, 2 figures include
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