23,465 research outputs found

    Federal incentives for industrial modernization: Historical review and future opportunities

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    Concerns over the aging of the U.S. aerospace industrial base led DOD to introduce first its Technology Modernization (Tech Mod) Program, and more recently the Industrial Modernization Incentive Program (IMIP). These incentives include productivity shared savings rewards, contractor investment protection to allow for amortization of plant and equipment, and subcontractor/vendor participation. The purpose here is to review DOD IMIP and to evaluate whether a similar program is feasible for NASA and other non-DOD agencies. The IMIP methodology is of interest to industrial engineers because it provides a structured, disciplined approach to identifying productivity improvement opportunities and documenting their expected benefit. However, it is shown that more research on predicting and validating cost avoidance is needed

    Dilution jet mixing program, phase 3

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    The main objectives for the NASA Jet Mixing Phase 3 program were: extension of the data base on the mixing of single sided rows of jets in a confined cross flow to discrete slots, including streamlined, bluff, and angled injections; quantification of the effects of geometrical and flow parameters on penetration and mixing of multiple rows of jets into a confined flow; investigation of in-line, staggered, and dissimilar hole configurations; and development of empirical correlations for predicting temperature distributions for discrete slots and multiple rows of dilution holes

    Feasibility study of inlet shock stability system of YF-12

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    The feasibility of self actuating bleed valves as a shock stabilization system in the inlet of the YF-12 is considered for vortex valves, slide valves, and poppet valves. Analytical estimation of valve performance indicates that only the slide and poppet valves located in the inlet cowl can meet the desired steady state stabilizing flows, and of the two the poppet valve is substantially faster in response to dynamic disturbances. The poppet valve is, therefore, selected as the best shock stability system for the YF-12 inlet

    Reentrant violation of special relativity in the low-energy corner

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    In the effective relativistic quantum field theories the energy region, where the special relativity holds, can be sandwiched from both the high and low energies sides by domains where the special relativity is violated. An example is provided by 3He-A where the relativistic quantum field theory emerges as the effective theory. The reentrant violation of the special relativity in the ultralow energy corner is accompanied by the redistribution of the momentum-space topological charges between the fermionic flavors. At this ultralow energy an exotic massless fermion with the topological charge N3=2N_3=2 arises, whose energy spectrum mixes the classical and relativistic behavior. This effect can lead to neutrino oscillations if neutrino flavors are still massless at this energy scale.Comment: RevTeX file, 5 pages, one figure, submitted to JETP Let

    Apollo particles and fields subsatellite magnetometer experiment

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    The results of the Apollo 15 subsatellite magnetometer experiment are reported. The magnetometer is described including the operation, and specifications. Orbit plots presented are altitude versus time, selenographic longitude versus latitude, and the ecliptic projection of the earth-moon system. The lunar magnetic field, solar wind interaction with the moon, the transfer function of the moon, and the plasma sheet interaction with the moon are discussed

    Jet Modification in a Brick of QGP Matter

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    We have implemented the LPM effect into a microscopic transport model with partonic degrees of freedom by following the algorithm of Zapp & Wiedemann. The Landau-Pomeranchuk-Migdal (LPM) effect is a quantum interference process that modifies the emission of radiation in the presence of a dense medium. In QCD this results in a quadratic length dependence for radiative energy loss. This is an important effect for the modification of jets by their passage through the QGP. We verify the leading parton energy loss in the model against the leading order Baier-Dokshitzer-Mueller-Peigne-Schiff-Zakharov (BDMPS-Z) result. We apply our model to the recent observations of the modification of di-jets at the LHC.Comment: Presented at Panic 1

    The Mass Operator in the Light-Cone Representation

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    I argue that for the case of fermions with nonzero bare mass there is a term in the matter density operator in the light-cone representation which has been omitted from previous calculations. The new term provides agreement with previous results in the equal-time representation for mass perturbation theory in the massive Schwinger model. For the DLCQ case the physics of the new term can be represented by an effective operator which acts in the DLCQ subspace, but the form of the term might be hard to guess and I do not know how to determine its coefficient from symmetry considerations.Comment: Revtex, 8 page

    S-Wave Scattering of Charged Fermions by a Magnetic Black Hole

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    We argue that, classically, ss-wave electrons incident on a magnetically charged black hole are swallowed with probability one: the reflection coefficient vanishes. However, quantum effects can lead to both electromagnetic and gravitational backscattering. We show that, for the case of extremal, magnetically charged, dilatonic black holes and a single flavor of low-energy charged particles, this backscattering is described by a perturbatively computable and unitary SS-matrix, and that the Hawking radiation in these modes is suppressed near extremality. The interesting and much more difficult case of several flavors is also discussed.Comment: 9p

    Dynamical confinement in bosonized QCD2

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    In the bosonized version of two dimensional theories non trivial boundary conditions (topology) play a crucial role. They are inevitable if one wants to describe non singlet states. In abelian bosonization, color is the charge of a topological current in terms of a non-linear meson field. We show that confinement appears as the dynamical collapse of the topology associated with its non trivial boundary conditions.Comment: 11 pages, figures not included, ftuv/92-

    General Solutions for Tunneling of Scalar Fields with Quartic Potentials in de Sitter Space

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    The tunneling rates for scalar fields with quartic potentials in de Sitter space in the limit of no gravitational back reaction are calculated numerically and the results are fitted by analytic formulae.Comment: (Contours in Figure 1 corrected, two-dimensional fitting coefficient corrected, references added.), 16 pages, KUNS 124
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