3,940 research outputs found

    Data analysis study and performance evaluation of the scanning laser Doppler system

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    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 132^{132}Sn studied with JYFLTRAP

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    The double Penning trap mass spectrometer JYFLTRAP has been employed to measure masses and excitation energies for 11/2−11/2^- isomers in 121^{121}Cd, 123^{123}Cd, 125^{125}Cd and 133^{133}Te, for 1/2−1/2^- isomers in 129^{129}In and 131^{131}In, and for 7−7^- isomers in 130^{130}Sn and 134^{134}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 132^{132}Sn. A new excitation energy of 144(4) keV has been determined for 123^{123}Cdm^m. A good agreement with the precisely known excitation energies of 121^{121}Cdm^m, 130^{130}Snm^m, and 134^{134}Sbm^m has been found.Comment: 10 pages, 6 figures, submitted to Phys. Rev.

    Networks of noisy oscillators with correlated degree and frequency dispersion

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    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

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    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

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    We obtain the exact beta function for N=2N=2 SUSY SU(2)SU(2) Yang-Mills theory and prove the nonperturbative Renormalization Group Equation ∂ΛF(a,Λ)=ΛΛ0∂Λ0F(a0,Λ0)e−2∫τ0τdxÎČ−1(x). \partial_\Lambda{\cal F}(a,\Lambda)= {\Lambda\over \Lambda_0}\partial_{\Lambda_0}{\cal F}(a_0,\Lambda_0) e^{-2\int_{\tau_0}^\tau {dx \beta^{-1}(x)}}. Comment: LaTex, 10 pg. Expanded introduction, references added, to appear in Phys. Rev. Let

    Nekrasov Functions and Exact Bohr-Sommerfeld Integrals

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    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

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    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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