29,139 research outputs found
Pressure-control purge panel for automatic butt welding
Modification of a purge panel for use in an automatic butt weld reduces the drop in pressure between the regulators and the weld head and tube purge fitting. The invention affects air regulators for plants, regulating circuits for pneumatic valves, and automatic welding machines
Isospin-projected nuclear level densities by the shell model Monte Carlo method
We have developed an efficient isospin projection method in the shell model
Monte Carlo approach for isospin-conserving Hamiltonians. For isoscalar
observables this projection method has the advantage of being exact sample by
sample. The isospin projection method allows us to take into account the proper
isospin dependence of the nuclear interaction, thus avoiding a sign problem
that such an interaction introduces in unprojected calculations. We apply our
method in the calculation of the isospin dependence of level densities in the
complete shell. We find that isospin-dependent corrections to the
total level density are particularly important for nuclei.Comment: 5 pages including 4 figure
Bayesian Geoadditive Seemingly Unrelated Regression
Parametric seemingly unrelated regression (SUR) models are a common tool for multivariate regression analysis when error variables are reasonably correlated, so that separate univariate analysis may result in inefficient estimates of covariate effects. A weakness of parametric models is that they require strong assumptions on the functional form of possibly nonlinear effects of metrical covariates. In this paper, we develop a Bayesian semiparametric SUR model, where the usual linear predictors are replaced by more flexible additive predictors allowing for simultaneous nonparametric estimation of such covariate effects and of spatial effects. The approach is based on appropriate smoothness priors which allow different forms and degrees of smoothness in a general framework. Inference is fully Bayesian and uses recent Markov chain Monte Carlo techniques
Effective chiral restoration in the rho'-meson in lattice QCD
In simulations with dynamical quarks it has been established that the ground
state rho in the infrared is a strong mixture of the two chiral representations
(0,1)+(1,0) and (1/2,1/2)_b. Its angular momentum content is approximately the
3S1 partial wave which is consistent with the quark model. Effective chiral
restoration in an excited rho-meson would require that in the infrared this
meson couples predominantly to one of the two representations. The variational
method allows one to study the mixing of interpolators with different chiral
transformation properties in the non-perturbatively determined excited state at
different resolution scales. We present results for the first excited state of
the rho-meson using simulations with n_f=2 dynamical quarks. We point out, that
in the infrared a leading contribution to rho'= rho(1450) comes from
(1/2,1/2)_b, in contrast to the rho. Its approximate chiral partner would be a
h_1(1380) state. The rho' wave function contains a significant contribution of
the 3D1 wave which is not consistent with the quark model prediction.Comment: 4 pp, a few short remarks have been added, a reference updated. To
appear in PR
FormCalc 8: Better Algebra and Vectorization
We present Version 8 of the Feynman-diagram calculator FormCalc. New features
include in particular significantly improved algebraic simplification as well
as vectorization of the generated code. The Cuba Library, used in FormCalc,
features checkpointing to disk for all integration algorithms.Comment: 7 pages, LaTeX, proceedings contribution to ACAT 2013, Beijing,
China, 16-21 May 201
Measurements in the Turbulent Boundary Layer at Constant Pressure in Subsonic and Supersonic Flow. Part 2: Laser-Doppler Velocity Measurements
A description of both the mean and the fluctuating components of the flow, and of the Reynolds stress as observed using a dual forward scattering laser-Doppler velocimeter is presented. A detailed description of the instrument and of the data analysis techniques were included in order to fully document the data. A detailed comparison was made between the laser-Doppler results and those presented in Part 1, and an assessment was made of the ability of the laser-Doppler velocimeter to measure the details of the flows involved
Non-Gaussian fixed point in four-dimensional pure compact U(1) gauge theory on the lattice
The line of phase transitions, separating the confinement and the Coulomb
phases in the four-dimensional pure compact U(1) gauge theory with extended
Wilson action, is reconsidered. We present new numerical evidence that a part
of this line, including the original Wilson action, is of second order. By
means of a high precision simulation on homogeneous lattices on a sphere we
find that along this line the scaling behavior is determined by one fixed point
with distinctly non-Gaussian critical exponent nu = 0.365(8). This makes the
existence of a nontrivial and nonasymptotically free four-dimensional pure U(1)
gauge theory in the continuum very probable. The universality and duality
arguments suggest that this conclusion holds also for the monopole loop gas,
for the noncompact abelian Higgs model at large negative squared bare mass, and
for the corresponding effective string theory.Comment: 11 pages, LaTeX, 2 figure
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