1,904 research outputs found

    Rise of Kp Total Cross Section and Universality

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    The increase of the measured hadronic total cross sections at the highest energies is empirically described by squared log of center-of-mass energy sqrt s as sigma(tot)= B (log s)2, consistent with the energy dependence of the Froissart unitarity bound. The coefficient B is argued to have a universal value, but this is not proved directly from QCD. In the previous tests of this universality, the p(pbar)p, pi p, and K p forward scatterings were analyzed independently and found to be consistent with B(pp) = B(pip) = B(Kp), although the determined value of B(Kp) had large uncertainty. In the present work, we have further analyzed forward Kp scattering to obtain a more exact value of B(Kp). Making use of continuous moment sum rules(CMSR) we have fully exploited the information of low-energy scattering data to predict the high-energy behavior of the amplitude hrough duality. The estimation of B(Kp) is improved remarkably, and our result strongly supports the universality of B.Comment: 12 pages, 3 figure

    Some path-following techniques for solution of nonlinear equations and comparison with parametric differentiation

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    Some path-following techniques are described and compared with other methods. Use of multipurpose techniques that can be used at more than one stage of the path-following computation results in a system that is relatively simple to understand, program, and use. Comparison of path-following methods with the method of parametric differentiation reveals definite advantages for the path-following methods. The fact that parametric differentiation has found a broader range of applications indicates that path-following methods have been underutilized

    A streamline curvature method for design of supercritical and subcritical airfoils

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    An airfoil design procedure, applicable to both subcritical and supercritical airfoils, is described. The method is based on the streamline curvature velocity equation. Several examples illustrating this method are presented and discussed

    Continuously operating induction plasma accelerator Patent

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    Continuous operation, single phased, induction plasma accelerator producing supersonic speed

    Estimation of attainable leading-edge thrust for wings at subsonic and supersonic speeds

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    The factors which place limits on the theoretical leading edge thrust are identified. An empirical method for the estimation of attainable thrust is presented. The method is based on the use of simple sweep theory to permit a two dimensional analysis, the use of theoretical airfoil programs to define thrust dependence on local geometric characteristics, and the examination of experimental two dimensional airfoil data to define limitations imposed by local Mach numbers and Reynolds numbers. Comparisons of theoretical and experimental aerodynamic characteristics for a series of wing body configurations are examined

    Laboratory investigation of diffraction and reflection of sonic booms by buildings

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    Laboratory investigation of diffraction and reflection of sonic booms by building

    The MicroJansky Radio Galaxy Population

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    We use highly spectroscopically complete observations of the radio sources from the VLA 1.4 GHz survey of the HDF-N region to study the faint radio galaxy population and its evolution. We spectrally classify the sources into four spectral types: absorbers, star formers, Seyfert galaxies, and broad-line AGNs, and we analyze their properties by type. We supplement the spectroscopic redshifts with photometric redshifts measured from the rest-frame UV to MIR spectral energy distributions. Using deep X-ray observations of the field, we do not confirm the existence of an X-ray-radio correlation for star-forming galaxies. We also do not observe any correlations between 1.4 GHz flux and R magnitude or redshift. We find that the radio powers of the host galaxies rise dramatically with increasing redshift, while the optical properties of the host galaxies show at most small changes. Assuming that the locally determined FIR-radio correlation holds at high redshifts, we estimate total FIR luminosities for the radio sources. We note that the FIR luminosity estimates for any radio-loud AGNs will be overestimates. Considering only the radio sources with quasar-like bolometric luminosities, we find a maximum ratio of candidate highly-obscured AGNs to X-ray-luminous (>10^42 ergs/s) sources of about 1.9. We use source-stacking analyses to measure the X-ray surface brightnesses of various X-ray and radio populations. We find the contributions to the 4-8 keV light from our candidate highly-obscured AGNs to be very small, and hence these sources are unable to account for the light that has been suggested may be missing at these energies.Comment: 20 pages, Accepted by The Astrophysical Journal (scheduled for 1 Jan 2007), color figures 2 and 3 can be found at http://www.astro.wisc.edu/~barger/radiopaper.htm

    An Extremely Deep Wide-Field Near-Infrared Survey: Bright Galaxy Counts and Local Large Scale Structure

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    We present a deep, wide-field near-infrared (NIR) survey over five widely separated fields at high Galactic latitude covering a total of ~ 3 deg^2 in J, H, and Ks. The deepest areas of the data (~ 0.25 deg^2) extend to a 5 sigma limiting magnitude of JHKs > 24 in the AB magnitude system. Although depth and area vary from field to field, the overall depth and large area of this dataset make it one of the deepest wide-field NIR imaging surveys to date. This paper discusses the observations, data reduction, and bright galaxy counts in these fields. We compare the slope of the bright galaxy counts with the Two Micron All Sky Survey (2MASS) and other counts from the literature and explore the relationship between slope and supergalactic latitude. The slope near the supergalactic equator is sub- Euclidean on average pointing to the possibility of a decreasing average space density of galaxies by ~ 10-15% over scales of ~ 250-350 Mpc. On the contrary, the slope at high supergalactic latitudes is strongly super-Euclidean on average suggesting an increase in the space density of galaxies as one moves from the voids just above and below the supergalactic plane out to distances of ~ 250-350 Mpc. These results suggest that local large scale structure could be responsible for large discrepancies in the measured slope between different studies in the past. In addition, the local universe away from the supergalactic plane appears to be underdense by ~ 25-100% relative to the space densities of a few hundred megaparsecs distant. Subject headings: cosmology: observations and large scale structure of universe-galaxies: fundamental parameters (counts)-infrared: galaxiesComment: Accepted to ApJS, 18 Pages, 14 Figures, 8 Table

    Investigation of flow characteristics over missile bodies at supersonic speeds

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    Three missile body shapes tested at Mach numbers of 1.50, 2.16, and 2.86 with angles of attack up to 30 degrees are described. The flow characteristics for each body shape are examined. The measured aerodynamic forces and moments are presented. The use of flow visualization techniques are described and the results such as vortex effects are discussed
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