4,054 research outputs found

    Energy Efficient Engine exhaust mixer model technology report addendum; phase 3 test program

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    The Phase 3 exhaust mixer test program was conducted to explore the trends established during previous Phases 1 and 2. Combinations of mixer design parameters were tested. Phase 3 testing showed that the best performance achievable within tailpipe length and diameter constraints is 2.55 percent better than an optimized separate flow base line. A reduced penetration design achieved about the same overall performance level at a substantially lower level of excess pressure loss but with a small reduction in mixing. To improve reliability of the data, the hot and cold flow thrust coefficient analysis used in Phases 1 and 2 was augmented by calculating percent mixing from traverse data. Relative change in percent mixing between configurations was determined from thrust and flow coefficient increments. The calculation procedure developed was found to be a useful tool in assessing mixer performance. Detailed flow field data were obtained to facilitate calibration of computer codes

    Dipole excitation and geometry of borromean nuclei

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    We analyze the Coulomb breakup cross sections of 11^{11}Li and 6^6He nuclei using a three-body model with a density-dependent contact interaction. We show that the concentration of the B(E1) strength near the threshold can be well reproduced with this model. With the help of the calculated B(E1) value, we extract the root-mean-square (rms) distance between the core nucleus and the center of mass of two valence neutrons without resorting to the sum rule, which may suffer from unphysical Pauli forbidden transitions. Together with the empirical rms distance between the neutrons obtained from the matter radius study and also from the three-body correlation study in the break-up reaction, we convert these rms distances to the mean opening angle between the valence neutrons from the core nucleus. We find that the obtained mean opening angles in 11^{11}Li and 6^6He agree with the three-body model predictions.Comment: 4 pages, 4 eps figure

    A Simple Explanation for the X(3872) Mass Shift Observed for Decay to D^{*0} {D^0}bar

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    We propose a simple explanation for the increase of approximately 3 MeV/c^2 in the mass value of the X(3872) obtained from D^{*0} {D^0}bar decay relative to that obtained from decay to J/psi pi+ pi-. If the total width of the X(3872) is 2-3 MeV, the peak position in the D^{*0} {D^0}bar invariant mass distribution is sensitive to the final state orbital angular momentum because of the proximity of the X(3872) to D^{*0} {D^0}bar threshold. We show that for total width 3 MeV and one unit of orbital angular momentum, a mass shift ~3 MeV/c^2 is obtained; experimental mass resolution should slightly increase this value. A consequence is that spin-parity 2^- is favored for the X(3872).Comment: 3.5 pages, 4 eps figure

    Cryogenic zero-gravity prototype vent system

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    Design, fabrication, and tests of prototype cryogenic zero-gravity heat exchanger vent syste

    Low energy bounds on Poincare violation in causal set theory

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    In the causal set approach to quantum gravity, Poincar\'{e} symmetry is modified by swerving in spacetime, induced by the random lattice discretization of the space-time structure. The broken translational symmetry at short distances is argued to lead to a residual diffusion in momentum space, whereby a particle can acquire energy and momentum by drift along its mass shell and a system in equilibrium can spontaneously heat up. We consider bounds on the rate of momentum space diffusion coming from astrophysical molecular clouds, nuclear stability and cosmological neutrino background. We find that the strongest limits come from relic neutrinos, which we estimate to constrain the momentum space diffusion constant by k<1061GeV3k < 10^{-61} {\rm GeV}^3 for neutrinos with masses mν>0.01eVm_\nu > 0.01 {\rm eV}, improving the previously quoted bounds by roughly 17 orders of magnitude.Comment: Additional discussion about behavior of alpha particles in nuclei added. Version matches that accepted in PR

    Motion Tomography of a single trapped ion

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    A method for the experimental reconstruction of the quantum state of motion for a single trapped ion is proposed. It is based on the measurement of the ground state population of the trap after a sudden change of the trapping potential. In particular, we show how the Q function and the quadrature distribution can be measured directly. In an example we demonstrate the principle and analyze the sensibility of the reconstruction process to experimental uncertainties as well as to finite grid limitations. Our method is not restricted to the Lamb-Dicke Limit and works in one or more dimensions.Comment: 4 pages, Revtex format, 4 postscript figures, changed typographical error

    Turbofan forced mixer lobe flow modeling. Part 3: Application to augment engines

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    Military engines frequently need large quantities of thrust for short periods of time. The addition of an augmentor can provide such thrust increases but with a penalty of increased duct length and engine weight. The addition of a forced mixer to the augmentor improves performance and reduces the penalty, as well as providing a method for siting the required flame holders. In this report two augmentor concepts are investigated: a swirl-mixer augmentor and a mixer-flameholder augmentor. Several designs for each concept are included and an experimental assessment of one of the swirl-mixer augmentors is presented

    Symmetry energy and neutron-proton radii studies with a Wigner-Heisenberg monopole-monopole interaction

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    The symmetry energy in nuclei is studied using a monopole-monopole two boby interaction which has an isospin dependent term. A Hartree theory is developed for this interaction which has an oscillator shell model basis with corresponding shell structure. The role of shell structure on the symmetry energy is then studied. We also find that the strength of the Heisenberg interaction is very important for understanding the difference between proton and neutron radii and features associated with halo nuclei. PACS numbers: 21.10.Sf, 21.65Cd, 21.65EfComment: 1 table, i figur

    Self-Criticism, Neediness, and Distress Among Women Undergoing Treatment for Breast Cancer: A Preliminary Test of the Moderating Role of Adjustment to Illness

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    A diagnosis of cancer can be extremely stressful, and for that reason, cancer patients’ adjustment has been widely studied. Little is known, however, about how patients’ personality vulnerabilities affect their adjustment to cancer. The present study examined the moderating role of several psychological strategies of adjustment to cancer in the associations between the personality predispositions of self-criticism and neediness and distress among women diagnosed with breast cancer. Portuguese women who had been diagnosed with breast cancer for the first time (n _ 50) completed the Depressive Experiences Questionnaire, the Hospital Anxiety and Depression Scale, and the Mini-Mental Adjustment to Cancer Scale questionnaires. Both self-criticism and neediness were found to be associated with increased levels of distress, with a stronger association observed for neediness. Hierarchical regressions indicated that more adaptive adjustment to cancer (i.e., low levels of helplessness/hopelessness, low levels of anxious preoccupation, high levels of fatalism, and high levels of fighting spirit) moderates the association between neediness and distress. There was no evidence that any of the adjustment variables had any mediating effect on the relationship between the personality variables (self-criticism and neediness) and distress. Results are discussed in the context of personality vulnerability and maladaptive psychological response to the disease as a stressful life event. Implications for treatment are discussed. Though promising, the results are preliminary and more research on larger samples is warranted
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