Search results for "One half"
showing 5 items of 5 documents
Extending Brauer's Height Zero Conjecture to Blocks with Nonabelian Defect Groups
2013
We propose a generalization of Brauer?s Height Zero Conjecture that considers positive heights. We give strong evidence supporting one half of the generalization and obtain some partial results regarding the other half.
Spreading dynamics of three-dimensional droplets by the lattice-Boltzmann method
2000
Abstract We have simulated spreading of small droplets on smooth and rough solid surfaces using the three-dimensional lattice-Boltzmann method. We present results for the influence of the initial distance and shape of the drop from the surface on scaling of droplet radius R as a function of time. For relatively flat initial drop shapes our observations are consistent with Tanner's law R ∼ t q , where q =1/10. For increasingly spherical initial shapes, the exponent q increases rapidly being above one half for spherical droplets initially just above the surface. As expected, surface roughness slows down spreading, decreases the final drop radius, and results in irregular droplet shape due to …
Analysis of the static and dynamic behaviour of a magnetic liquid seal
1985
A rotating shaft seal, using ferrofluid between biconical truncated magnetic poles, is analysed both in static and dynamic conditions. After solving Laplace's equation and allowing an approximate expression for the magnetic potential, the magnetic forces acting on the working fluid are obtained. It is thus possible to determine the baric field existing in static conditions and the highest tolerable pressure jump. In the case of dynamic working the flow is schematized by two interior regions, where the azimuthal velocity prevails, and four boundary layers on the walls, where meridional transport of fluid takes place. Assuming laminar motion, by means of a perturbation procedure it is possibl…
Measuring Inaccessible Residual Stresses Using Multiple Methods and Superposition
2010
The traditional contour method maps a single component of residual stress by cutting a body carefully in two and measuring the contour of the cut surface. The cut also exposes previously inaccessible regions of the body to residual stress measurement using a variety of other techniques, but the stresses have been changed by the relaxation after cutting. In this paper, it is shown that superposition of stresses measured post-cutting with results from the contour method analysis can determine the original (pre-cut) residual stresses. The general superposition theory using Bueckner’s principle is developed and limitations are discussed. The procedure is experimentally demonstrated by determini…
A linear Fe-O-Fe unit in bis(dibenzyldimethylammonium) mu-oxo-bis[tribromoferrate(III)].
2006
The title compound, (C 16 H 20 )N) 2 [Fe 2 Br 6 O], crystallizes with one dibenzyldimethylammonium cation and one half of a μ-oxo-bis[tribromoferrate(III)] anion in the asymmetric unit. The bridging oxo group is situated on an inversion centre, resulting in a linear conformation for the Fe-O-Fe unit. The iron(III) cations have tetrahedral geometry, with bond angles in the range 106.8 (1)-112.2 (1)°. The ion pairs are held together by Coulombic forces and C-H···Br hydrogen bonds. Each Br - anion forms one hydrogen bond. No C-H···O hydrogen bonds are found between the O atom in the Fe-O-Fe unit and surrounding counter-cations, consistent with the linear configuration of the Fe-O-Fe unit.