19,683 research outputs found
The use of genetic algorithms to maximize the performance of a partially lined screened room
This paper shows that it is possible to use genetic algorithms to optimize the layout of ferrite tile absorber in a partially lined screened enclosure to produce a "best" performance. The enclosure and absorber are modeled using TLM modeling techniques and the performance is determined by comparison with theoretical normalized site attenuation of free space. The results show that it is possible to cover just 80% of the surface of the enclosure with ferrite absorber and obtain a response which is within +/-4 dB of the free space response between 40 and 200 MHz
Bessel processes, the Brownian snake and super-Brownian motion
We prove that, both for the Brownian snake and for super-Brownian motion in
dimension one, the historical path corresponding to the minimal spatial
position is a Bessel process of dimension -5. We also discuss a spine
decomposition for the Brownian snake conditioned on the minimizing path.Comment: Submitted to the special volume of S\'eminaire de Probabilit\'es in
memory of Marc Yo
SUSY QCD Corrections to Higgs-b Production : Is the \Delta_b Approximation Accurate?
The associated production of a Higgs boson with a b quark is a discovery
channel for the lightest MSSM neutral Higgs boson. We consider the SUSY QCD
contributions from squarks and gluinos and discuss the decoupling properties of
these effects. A detailed comparison of our exact order(alpha_s) results with
those of a widely used effective Lagrangian approach, the \Delta_b
approximation, is presented. The \Delta_b approximation is shown to accurately
reproduce the exact one-loop SQCD result to within a few percent over a wide
range of parameter space.Comment: figures added, version to be published in Phys Rev
Supersymmetric approximations to the 3D supersymmetric O(N) model
We develop several non-perturbative approximations for studying the dynamics
of a supersymmetric O(N) model which preserve supersymmetry. We study the phase
structure of the vacuum in both the leading order in large-N approximation as
well as in the Hartree approximation, and derive the finite temperature
renormalized effective potential. We derive the exact Schwinger-Dyson equations
for the superfield Green functions and develop the machinery for going beyond
the next to leading order in large-N approximation using a truncation of these
equations which can also be derived from a two-particle irreducible effective
action.Comment: 16 pages, 3 figure
Improved Plane-Wave Illumination for TLM Method
An efficient solution to the problems associated with plane wave illumination of a scattering body in a TLM mesh is presented. The solution is equivalent to a partial implementation of the Huygens surface [1] used in the time-domain finite difference (TDFD) method, but, additionally, accounts for dispersion effects
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