9,704 research outputs found

    Characteristics of the motions, turbulence intensity, diffusivity, flux of momentum and sensible heat in the upper atmosphere

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    Analyses of the meteorological rocket data obtained from an experiment conducted at 3-hour intervals at 8 western meridional rocket stations are presented. Large variations in the meridional wind contribute substantially to overall turbulence in the tropical stratosphere. The solar semidiurnal component of wind oscillations in the tropics was observed to be much higher than predicted by theory, often exceeding the magnitude of the diurnal amplitude throughout the stratosphere. The observed value of the solar diurnal amplitude in the stratosphere was in line with theoretical prediction. The solar terdiurnal amplitudes for temperature, meridional and zonal winds were non-negligible and must be considered in any harmonic analysis. Phase angle variation with height was rapid for all harmonics; however, there was general agreement between predicted and observed phase angles. Because of large changes in the mean winds in the mesosphere with season, harmonic determinations are difficult. There appear to be large zonal wind changes even within the same season as mentioned previously. Turbulence diffusivity in the upper stratosphere is greater near the equator than in the mid-latitudes

    QCD4_4 Glueball Masses from AdS-6 Black Hole Description

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    By using the generalized version of gauge/gravity correspondence, we study the mass spectra of several typical QCD4_4 glueballs in the framework of AdS6_6 black hole metric of Einstein gravity theory. The obtained glueball mass spectra are numerically in agreement with those from the AdS7×S47 \times S^4 black hole metric of the 11-dimensional supergravity.Comment: 10 pages, references updated and minor change

    The effects of natural, forced and thermoelectric magnetohydrodynamic convection during the solidification of thin sample alloys

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    Using a fully coupled transient 3-dimensional numerical model, the effects of convection on the microstructural evolution of a thin sample of Ga-In25%wt. was predicted. The effects of natural convection, forced convection and thermoelectric magnetohydrodynamics were investigated numerically. A comparison of the numerical results is made to experimental results for natural convection and forced convection. In the case of natural convection, density variations within the liquid cause plumes of solute to be ejected into the bulk. When forced convection is applied observed effects include the suppression of solute plumes, preferential secondary arm growth and an increase in primary arm spacing. These effects were observed both numerically and experimentally. By applying an external magnetic field inter-dendritic flow is generated by thermoelectrically induced Lorentz forces, while bulk flow experiences an electromagnetic damping force. The former causes preferential secondary growth, while the latter slows the formation of solute plumes. This work highlights that the application of external forces can be a valuable tool for tailoring the microstructure and ultimately the macroscopic material properties

    Discovering the Higgs Bosons of Minimal Supersymmetry with Muons and a Bottom Quark

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    We investigate the prospects for the discovery at the CERN Large Hadron Collider of a neutral Higgs boson produced with one bottom quark followed by Higgs decay into a muon pair. We work within the framework of the minimal supersymmetric model. The dominant physics background from the production of bμ+μb \mu^+\mu^-, jμ+μj\mu^+\mu^-, j=g,u,d,s,c, and bbˉW+Wb {\bar b} W^+W^- is calculated with realistic acceptance cuts. Promising results are found for the CP-odd pseudoscalar (A0A^0) and the heavier CP-even scalar (H0H^0) Higgs bosons with masses up to 600 GeV. This discovery channel with one energetic bottom quark greatly improves the discovery potential of the LHC beyond the inclusive channel ppϕ0μ+μ+Xpp\to \phi^0\to \mu^+\mu^- +X.Comment: Version to appear in Phys. Rev. Let

    Vibration of a circular cylindrical elastic tank, partially filled with an incompressible fluid, undergoing an axial acceleration composed of a uniform and a periodic component technical memorandum no. 102

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    Forced vibration of circular cylindrical elastic shell partially filled with incompressible liquid and initially at rest in uniform gravitational fiel

    The Chern-Simons Coefficient in Supersymmetric Non-abelian Chern-Simons Higgs Theories

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    By taking into account the effect of the would be Chern-Simons term, we calculate the quantum correction to the Chern-Simons coefficient in supersymmetric Chern-Simons Higgs theories with matter fields in the fundamental representation of SU(n). Because of supersymmetry, the corrections in the symmetric and Higgs phases are identical. In particular, the correction is vanishing for N=3 supersymmetric Chern-Simons Higgs theories. The result should be quite general, and have important implication for the more interesting case when the Higgs is in the adjoint representation.Comment: more references and explanation about rgularization dpendence are included, 13 pages, 1 figure, latex with revte

    Higgs Boson Discovery Potential of LHC in the Channel ppγγ+jetpp \to\gamma\gamma+jet

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    We discuss the SM Higgs discovery potential of LHC in the reaction ppH+jetγγ+jetpp\to H+ jet\to\gamma\gamma+jet when the jet is observed at sufficiently high EtE_t to be reliably identified. We conclude that this channel gives promising discovery possibilities for the Higgs boson mass range 100-140 GeV, during LHC operation at a low luminosity. With 30 fb1^{-1} of accumulated data and for MH=120M_H=120 GeV about 100 signal events could be observed with the number of background events larger by a factor of 2 only, showing a signal significance S/B7S/\sqrt{B}\sim 7. We use the difference of distributions in the partonic subprocess energy s^\sqrt{\hat s} for the signal and background for a better separation of the signal.Comment: 15 pages including 6 figures, LaTeX, use epsfig.sty. To appear in Phys.Lett.B. In this replacement minor LaTeX improvements are mad

    Developing and utilizing an Euler computational method for predicting the airframe/propulsion effects for an aft-mounted turboprop transport. Volume 2: User guide

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    This manual explains how to use an Euler based computational method for predicting the airframe/propulsion integration effects for an aft-mounted turboprop transport. The propeller power effects are simulated by the actuator disk concept. This method consists of global flow field analysis and the embedded flow solution for predicting the detailed flow characteristics in the local vicinity of an aft-mounted propfan engine. The computational procedure includes the use of several computer programs performing four main functions: grid generation, Euler solution, grid embedding, and streamline tracing. This user's guide provides information for these programs, including input data preparations with sample input decks, output descriptions, and sample Unix scripts for program execution in the UNICOS environment

    How Unsplittable-Flow-Covering helps Scheduling with Job-Dependent Cost Functions

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    Generalizing many well-known and natural scheduling problems, scheduling with job-specific cost functions has gained a lot of attention recently. In this setting, each job incurs a cost depending on its completion time, given by a private cost function, and one seeks to schedule the jobs to minimize the total sum of these costs. The framework captures many important scheduling objectives such as weighted flow time or weighted tardiness. Still, the general case as well as the mentioned special cases are far from being very well understood yet, even for only one machine. Aiming for better general understanding of this problem, in this paper we focus on the case of uniform job release dates on one machine for which the state of the art is a 4-approximation algorithm. This is true even for a special case that is equivalent to the covering version of the well-studied and prominent unsplittable flow on a path problem, which is interesting in its own right. For that covering problem, we present a quasi-polynomial time (1+ϵ)(1+\epsilon)-approximation algorithm that yields an (e+ϵ)(e+\epsilon)-approximation for the above scheduling problem. Moreover, for the latter we devise the best possible resource augmentation result regarding speed: a polynomial time algorithm which computes a solution with \emph{optimal }cost at 1+ϵ1+\epsilon speedup. Finally, we present an elegant QPTAS for the special case where the cost functions of the jobs fall into at most logn\log n many classes. This algorithm allows the jobs even to have up to logn\log n many distinct release dates.Comment: 2 pages, 1 figur
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