33,246 research outputs found

    Separation of gas from liquid in a two-phase flow system

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    Separation system causes jets which leave two-phase nozzles to impinge on each other, so that liquid from jets tends to coalesce in center of combined jet streams while gas phase is forced to outer periphery. Thus, because liquid coalescence is achieved without resort to separation with solid surfaces, cycle efficiency is improved

    Effect of a simulated engine jet blowing above an arrow wing at Mach 2.0

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    The effects of a gas jet simulating a turbojet engine exhaust blowing above a cambered and twisted arrow wing were investigated. Tests were conducted in the Langley 4-foot supersonic pressure tunnel at a Mach number of 2.0. Nozzle pressure ratios from 1 to 64 were tested with both helium and air used as jet gases. The tests were conducted at angles of attack from -2 deg to 8 deg at a Reynolds number of 9,840,000 per meter. Only the forces and moments on the wing were measured. Results of the investigation indicated that the jet blowing over the wing caused reductions in maximum lift-drag ratio of about 4 percent for helium and 6 percent for air at their respective design nozzle pressure ratios, relative to jet-off data. Moderate changes in the longitudinal, vertical, or angular positions of the jet relative to the wing had little effect on the wing aerodynamic characteristics

    Splitting Sensitivity of the Ground and 7.6 eV Isomeric States of 229Th

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    The lowest-known excited state in nuclei is the 7.6 eV isomer of 229Th. This energy is within the range of laser-based investigations that could allow accurate measurements of possible temporal variation of this energy splitting. This in turn could probe temporal variation of the fine-structure constant or other parameters in the nuclear Hamiltonian. We investigate the sensitivity of this transition energy to these quantities. We find that the two states are predicted to have identical deformations and thus the same Coulomb energies within the accuracy of the model (viz., within roughly 30 keV). We therefore find no enhanced sensitivity to variation of the fine-structure constant. In the case of the strong interaction the energy splitting is found to have a complicated dependence on several parameters of the interaction, which makes an accurate prediction of sensitivity to temporal changes of fundamental constants problematical. Neither the strong- nor Coulomb-interaction contributions to the energy splitting of this doublet can be constrained within an accuracy better than a few tens of keV, so that only upper limits can be set on the possible sensitivity to temporal variations of the fundamental constants.Comment: 4 pages, 2 figure

    Neighborhood school characteristics: what signals quality to homebuyers?

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    Popular wisdom and economic research suggest that the quality of the neighborhood school should be an important determinant of housing values. Many researchers have found that housing values are higher where school spending or student test scores are higher. However, few economists consider these characteristics good indicators of school quality. Meanwhile, no one has examined whether the economists' notion of school quality-the school's marginal effect on students-is a school characteristic that matters to homebuyers. ; Using a model of new home purchases and historical data on homes in the Dallas Independent School District (DISD), Kathy Hayes and Lori Taylor demonstrate that property values do reflect the characteristics of the neighborhood school. They present evidence that property values reflect student test scores but not school expenditures. Interestingly, they also find that the relationship between test scores and property values arises from an underlying relationship between property values and the marginal effects of schools. Thus, their analysis suggests that homebuyers and economists share the same definition of school quality.Education ; Property tax
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