70 research outputs found
An apprach to generate large and small leptonic mixing angles
We take up the point of view that Yukawa couplings can be either 0 or 1, and
the mass patterns of fermions are generated purely from the structure of the
Yukawa matrices. We utilize such neutrino as well as charged leptonic textures
which lead to (maximal) mixing angles of in each sector for relevant
transitions. The combined leptonic CKM mixing angles are
which lead to very small relevant to solar neutrino and LSND
experiments. We propose that on the other hand the absence of the charged
leptonic partner of the sterile neutrino maintains the angle from the
neutrino sector for the transition and hence
atmospheric neutrino anomaly is explained through maximal mixing
p-Branes from Generalized Yang-Mills Theory
We consider the reduced, quenched version of a generalized Yang-Mills action
in 4k-dimensional spacetime. This is a new kind of matrix theory which is
mapped through the Weyl-Wigner-Moyal correspondence into a field theory over a
non-commutative phase space. We show that the ``classical'' limit of this field
theory is encoded into the effective action of an open, (4k-1)-dimensional,
bulk brane enclosed by a dynamical, Chern-Simons type, (4k-2)-dimensional,
boundary brane. The bulk action is a pure volume term, while the boundary
action carries all the dynamical degrees of freedom.Comment: 8 pages, LaTeX 2e, no figure
Crushing singularities in spacetimes with spherical, plane and hyperbolic symmetry
It is shown that the initial singularities in spatially compact spacetimes
with spherical, plane or hyperbolic symmetry admitting a compact constant mean
curvature hypersurface are crushing singularities when the matter content of
spacetime is described by the Vlasov equation (collisionless matter) or the
wave equation (massless scalar field). In the spherically symmetric case it is
further shown that if the spacetime admits a maximal slice then there are
crushing singularities both in the past and in the future. The essential
properties of the matter models chosen are that their energy-momentum tensors
satisfy certain inequalities and that they do not develop singularities in a
given regular background spacetime.Comment: 19 page
Nonlinear hydro turbine model having a surge tank.
yesThis paper models a hydro turbine based on the dynamic description of the hydraulic system having a surge tank and elastic water hammer. The dynamic of the hydraulic system is transformed from transfer function form into the differential equation model in relative value. This model is then combined with the motion equation of the main servomotor to form the nonlinear model of the hydro turbine, in which the power of the hydro turbine is calculated using algebraic equation. A new control model is thus proposed in which the dynamic of the surge tank is taken as an additional input of control items. As such, the complex hydraulic system is decomposed into a classical one penstock and one machine model with an additional input control. Therefore, the order of the system is descended. As a result, the feasibility of the system is largely improved. The simulated results show that the additional input of the surge tank is effective and the proposed method is realizable.National Natural Science Foundation of China (50839003, 50949037, 51179079), Natural Science Foundation of Yunnan Province (No. 2008GA027
Theory and Phenomenology of Type I strings and M-theory
The physical motivations and the basic construction rules for Type I strings
and M-theory compactifications are reviewed in light of the recent
developments. The first part contains the basic theoretical ingredients needed
for building four-dimensional supersymmetric models, models with broken
supersymmetry and for computing low-energy actions and quantum corrections to
them. The second part contains some phenomenological applications to brane
world scenarios with low values of the string scale and large extra dimensions.Comment: 129 pages, 7 eps figures, LaTeX, version to appear in Class. Quantum
Gra
Mon. Not. R. Astron. Soc. 000, 1-12 (2003) Printed 13 June 2003 (MN L A T E X style
We construct stable axially symmetric models of elliptical galaxies. For these models the particle density on phase space is a function of the particle energy and the third component of the angular momentum and is decreasing in the former. They are obtained as minimizers of suitably de ned energy-Casimir functionals, and this implies their nonlinear dynamical stability against axisymmetric perturbations. Since our analysis proceeds from a rigorous but purely mathematical point of view it should be interesting to determine if any of our models match observational data in astrophysics. The main purpose of these notes is to initiate some exchange of information between the astrophysics and the mathematics communities
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