75,830 research outputs found
Recursive integral method for transmission eigenvalues
Recently, a new eigenvalue problem, called the transmission eigenvalue
problem, has attracted many researchers. The problem arose in inverse
scattering theory for inhomogeneous media and has important applications in a
variety of inverse problems for target identification and nondestructive
testing. The problem is numerically challenging because it is non-selfadjoint
and nonlinear. In this paper, we propose a recursive integral method for
computing transmission eigenvalues from a finite element discretization of the
continuous problem. The method, which overcomes some difficulties of existing
methods, is based on eigenprojectors of compact operators. It is
self-correcting, can separate nearby eigenvalues, and does not require an
initial approximation based on some a priori spectral information. These
features make the method well suited for the transmission eigenvalue problem
whose spectrum is complicated. Numerical examples show that the method is
effective and robust.Comment: 18 pages, 8 figure
A systematic algorithm development for image processing feature extraction in automatic visual inspection : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in the Department of Production Technology, Massey University
Image processing techniques applied to modern quality control are described together with the development of feature extraction algorithms for automatic visual inspection. A real-time image processing hardware system already available in the Department of Production Technology is described and has been tested systematically for establishing an optimal threshold function. This systematic testing has been concerned with edge strength and system noise information. With the a priori information of system signal and noise, non-linear threshold functions have been established for real time edge detection. The performance of adaptive thresholding is described and the usefulness of this nonlinear approach is demonstrated from results using machined test samples. Examination and comparisons of thresholding techniques applied to several edge detection operators are presented. It is concluded that, the Roberts' operator with a non-linear thresholding function has the advantages of being simple, fast, accurate and cost effective in automatic visual inspection
Global Power Counting Analysis On Probing Electroweak Symmetry Breaking Mechanism At High Energy Colliders
We develop a precise power counting rule (a generalization of Weinberg's
counting method for the nonlinear sigma model) for the electroweak theories
formulated by chiral Lagrangians. Then we estimate the contributions of ``all''
next-to-leading order (NLO) bosonic operators to the amplitudes of the relevant
scattering processes which can be measured at high energy colliders, such as
the LHC and future Linear Colliders. Based upon these results, we globally
classify the sensitivities of testing all NLO bosonic operators for probing the
electroweak symmetry breaking mechanism at high energy colliders.Comment: Version Published in Physics Letters B. Latex, 12 pages, minor typos
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Universal Relations in Composite Higgs Models
We initiate a phenomenological study of `universal relations' in composite
Higgs models, which are dictated by nonlinear shift symmetries acting on the
125 GeV Higgs boson. These are relations among one Higgs couplings with two
electroweak gauge bosons (HVV), two Higgses couplings with two electroweak
gauge bosons (HHVV), one Higgs couplings with three electroweak gauge bosons
(HVVV), as well as triple gauge boson couplings (TGC), which are all controlled
by a single input parameter: the decay constant of the
pseudo-Nambu-Goldstone Higgs boson. Assuming custodial invariance in strong
sector, the relation is independent of the symmetry breaking pattern in the UV,
for an arbitrary symmetric coset . The complete list of corrections to
HVV, HHVV, HVVV and TGC couplings in composite Higgs models is presented to all
orders in , and up to four-derivative level, without referring to a
particular . We then present several examples of universal relations in
ratios of coefficients which could be extracted experimentally. Measuring the
universal relation requires a precision sensitive to effects of dimension-8
operators in the effective Lagrangian and highlights the importance of
verifying the tensor structure of HHVV interactions in the standard model,
which remains untested to date.Comment: 31 pages, 6 figure
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