3,940 research outputs found
Data analysis study and performance evaluation of the scanning laser Doppler system
A simulation program which provided information on theoretically expected vortex spectra, evaluations of potential algorithms, and expected location accuracies for given scan patterns is presented. Field tests using an aircraft engine flow field and aircraft vortices during flyby tests were compared to the results of the simulation. From these studies, a vortex location algorithm was developed which provided vortex location for one or two vortices as a function of time. Results of this algorithm used on data from flyby tests were used to study vortex transport, to evaluate system performance, and to provide suggestions for real-time vortex location algorithms. The results of real-time analysis were compared to those which were expected based on theoretical considerations
Isomeric states close to doubly magic Sn studied with JYFLTRAP
The double Penning trap mass spectrometer JYFLTRAP has been employed to
measure masses and excitation energies for isomers in Cd,
Cd, Cd and Te, for isomers in In and
In, and for isomers in Sn and Sb. These first
direct mass measurements of the Cd and In isomers reveal deviations to the
excitation energies based on results from beta-decay experiments and yield new
information on neutron- and proton-hole states close to Sn. A new
excitation energy of 144(4) keV has been determined for Cd. A good
agreement with the precisely known excitation energies of Cd,
Sn, and Sb has been found.Comment: 10 pages, 6 figures, submitted to Phys. Rev.
Networks of noisy oscillators with correlated degree and frequency dispersion
We investigate how correlations between the diversity of the connectivity of
networks and the dynamics at their nodes affect the macroscopic behavior. In
particular, we study the synchronization transition of coupled stochastic phase
oscillators that represent the node dynamics. Crucially in our work, the
variability in the number of connections of the nodes is correlated with the
width of the frequency distribution of the oscillators. By numerical
simulations on Erd\"os-R\'enyi networks, where the frequencies of the
oscillators are Gaussian distributed, we make the counterintuitive observation
that an increase in the strength of the correlation is accompanied by an
increase in the critical coupling strength for the onset of synchronization. We
further observe that the critical coupling can solely depend on the average
number of connections or even completely lose its dependence on the network
connectivity. Only beyond this state, a weighted mean-field approximation
breaks down. If noise is present, the correlations have to be stronger to yield
similar observations.Comment: 6 pages, 2 figure
Focused laser Doppler velocimeter
A system for remotely measuring velocities present in discrete volumes of air is described. A CO2 laser beam is focused by a telescope at such a volume, a focal volume, and within the focusable range, near field, of the telescope. The back scatter, or reflected light, principally from the focal volume, passes back through the telescope and is frequency compared with the original frequency of the laser, and the difference frequency or frequencies represent particle velocities in that focal volume
Nonperturbative Renormalization Group Equation and Beta Function in N=2 SUSY Yang-Mills
We obtain the exact beta function for SUSY Yang-Mills theory
and prove the nonperturbative Renormalization Group Equation Comment: LaTex, 10 pg. Expanded introduction, references added, to appear in
Phys. Rev. Let
Nekrasov Functions and Exact Bohr-Sommerfeld Integrals
In the case of SU(2), associated by the AGT relation to the 2d Liouville
theory, the Seiberg-Witten prepotential is constructed from the Bohr-Sommerfeld
periods of 1d sine-Gordon model. If the same construction is literally applied
to monodromies of exact wave functions, the prepotential turns into the
one-parametric Nekrasov prepotential F(a,\epsilon_1) with the other epsilon
parameter vanishing, \epsilon_2=0, and \epsilon_1 playing the role of the
Planck constant in the sine-Gordon Shroedinger equation, \hbar=\epsilon_1. This
seems to be in accordance with the recent claim in arXiv:0908.4052 and poses a
problem of describing the full Nekrasov function as a seemingly straightforward
double-parametric quantization of sine-Gordon model. This also provides a new
link between the Liouville and sine-Gordon theories.Comment: 10 page
A Soluble String Theory of Hadrons
We consider Penrose limits of the Klebanov-Strassler and Maldacena-Nunez
holographic duals to N =1 supersymmetric Yang-Mills. By focusing in on the IR
region we obtain exactly solvable string theory models. These represent the
nonrelativistic motion and low-lying excitations of heavy hadrons with mass
proportional to a large global charge. We argue that these hadrons, both
physically and mathematically, take the form of heavy nonrelativistic strings;
we term them "annulons." A simple toy model of a string boosted along a compact
circle allows us considerable insight into their properties. We also calculate
the Wilson loop carrying large global charge and show the effect of confinement
is quadratic, not linear, in the string tension.Comment: 40 pages, 1 figure; v2: typos correcte
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