19,442 research outputs found

    Properties of phase transitions of higher order

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    There is only limited experimental evidence for the existence in nature of phase transitions of Ehrenfest order greater than two. However, there is no physical reason for their non-existence, and such transitions certainly exist in a number of theoretical models in statistical physics and lattice field theory. Here, higher-order transitions are analysed through the medium of partition function zeros. Results concerning the distributions of zeros are derived as are scaling relations between some of the critical exponents.Comment: 6 pages, poster presented at Lattice 2005 (Spin and Higgs), Trinity College Dubli

    Comparison of flight data and analysis for hingeless rotor regressive inplane mode stability

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    Analytical and experimental data obtained during the development of the AH-56A covering stability of the regressive inplane mode, including coupling with other modes such as body and rotor plunge are reported. Data were obtained on two distinctly different control systems; both gyro controlled, but one with feathering moment feedback and the other with direct flapping feedback. A review was made of analytical procedures employed in investigating the stability of this mode and a comparison was made of the analytical and experimental data. The effect of certain parameters including blade droop, sweep, delta 3, alpha 1, vehicle roll inertia, inplane frequency, and rpm and forward speed on the mode were also reviewed. It was shown that the stability of this mode is treatable by analysis and that adequate stability is achievable without recourse to auxiliary inplane damping devices

    A numerical solution of the Navier-Stokes equations for chemically nonequilibrium, merged stagnation shock layers on spheres and two-dimensional cylinders in air

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    Results of solving the Navier-Stokes equations for chemically nonequilibrium, merged stagnation shock layers on spheres and two-dimensional cylinders are presented. The effects of wall catalysis and slip are also examined. The thin shock layer assumption is not made, and the thick viscous shock is allowed to develop within the computational domain. The results show good comparison with existing data. Due to the more pronounced merging of shock layer and boundary layer for the sphere, the heating rates for spheres become higher than those for cylinders as the altitude is increased

    Feasibility of conventional control techniques for large highly coupled elastic boost vehicles Final report

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    Control techniques for large highly-coupled elastic boost vehicles with elastic and fuel slosh mode frequencies close to desired control frequencies - motion equation

    Experimental rate coefficients for collisional excitation of lithium-like ions

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    Collisional excitation rates for lithium-like ions derived from diagnosed plasma produced in theta pinch device and line intensities emitted by these ion

    The 2000 Periastron Passage of PSR B1259-63

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    We report here on a sequence of 28 observations of the binary pulsar system PSR B1259-63/SS2883 at four radio frequencies made with the Australia Telescope Compact Array around the time of the 2000 periastron passage. Observations made on 2000 Sep 1 show that the pulsar's apparent rotation measure (RM) reached a maximum of −14800±1800-14800 \pm 1800 rad m−2^{-2}, some 700 times the value measured away from periastron, and is the largest astrophysical RM measured. This value, combined with the dispersion measure implies a magnetic field in the Be star's wind of 6 mG. We find that the light curve of the unpulsed emission is similar to that obtained during the 1997 periastron but that differences in detail imply that the emission disc of the Be star is thicker and/or of higher density. The behaviour of the light curve at late times is best modelled by the adiabatic expansion of a synchrotron bubble formed in the pulsar/disc interaction. The expansion rate of the bubble ∼12\sim 12 km s−1^{-1} is surprisingly low but the derived magnetic field of 1.6 G close to that expected.Comment: 8 pages, 6 figures, 3 tables, LaTeX (mn.sty). Accepted for publication in the Monthly Notices of the Royal Astronomical Society. Also available at http://astronomy.swin.edu.au/staff/tconnors/publications.htm
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