14,123 research outputs found

    Improved fiberglass-to-metal joint produces lighter stronger fiberglass strut

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    Axial tension and compression are transmitted between end fittings and fiberglass tube without depending on glass-to-metal bonding, conventional fasteners or combination of these things. Joint design significantly reduces both structural weight of strut and its cross-sectional area

    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

    Hierarchical Wigner Crystal at the Edge of Quantum Hall Bar

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    We show that quasiholes persist near the edge of incompressible Quantum Hall state forming a Wigner structure. The average density of quasiholes is fixed by electrostatics and decreases slowly with increasing distance from the edge. As we see from elementary reasoning, their specific arrangement can not be a regular Wigner lattice and shows a complex hierarchical structure of dislocations.Comment: LaTEX file. Ps figures upon reques

    Systems comparison of direct and relay link data return modes for advanced planetary missions

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    Advanced planetary missions using direct and relay link data return mode

    Scaling of magnetic monopoles in the pure compact QED

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    In the pure U(1) lattice gauge theory with the Villain action we find that the monopole mass in the Coulomb phase and the monopole condensate in the confinement phase scale according to simple power laws. This holds outside the coupling region in which on finite toroidal lattices the metastability phenomena occur. A natural explanation of the observed accuracy of the scaling behaviour would be the second order of the phase transition between both phases in the general space of couplings not far away from the Villain action.Comment: LATTICE99(Topology and Confinement) - 3 pages, 4 fig

    A Study of an Inverted Wing with Endplates in Ground Effect

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    The aerodynamics of an inverted wing with endplates in ground effect has been investigated using experimental methods. A wind tunnel containing a moving belt was used to reproduce the effect of the ground on the flow field and the measurements were made using Laser Doppler Anemometry (LDA). Flow visualization showed that the implementation of an endplate on a wing yields the formation of two corotating vortices originating from the top and the bottom of the endplate. Initially the effect of the size of the endplate and the height of the wing above the ground on the vortices behaviour was studied. Then, the most relevant configuration of the wing was studied using LDA measurements

    Quasiperiodic spin-orbit motion and spin tunes in storage rings

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    We present an in-depth analysis of the concept of spin precession frequency for integrable orbital motion in storage rings. Spin motion on the periodic closed orbit of a storage ring can be analyzed in terms of the Floquet theorem for equations of motion with periodic parameters and a spin precession frequency emerges in a Floquet exponent as an additional frequency of the system. To define a spin precession frequency on nonperiodic synchro-betatron orbits we exploit the important concept of quasiperiodicity. This allows a generalization of the Floquet theorem so that a spin precession frequency can be defined in this case too. This frequency appears in a Floquet-like exponent as an additional frequency in the system in analogy with the case of motion on the closed orbit. These circumstances lead naturally to the definition of the uniform precession rate and a definition of spin tune. A spin tune is a uniform precession rate obtained when certain conditions are fulfilled. Having defined spin tune we define spin-orbit resonance on synchro--betatron orbits and examine its consequences. We give conditions for the existence of uniform precession rates and spin tunes (e.g. where small divisors are controlled by applying a Diophantine condition) and illustrate the various aspects of our description with several examples. The formalism also suggests the use of spectral analysis to ``measure'' spin tune during computer simulations of spin motion on synchro-betatron orbits.Comment: 62 pages, 1 figure. A slight extension of the published versio

    Diet-induced obesity impairs mammary development and lactogenesis in murine mammary gland

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    We have developed a mouse model of diet-induced obesity that shows numerous abnormalities relating to mammary gland function. Animals ate 40% more calories when offered a high-fat diet and gained weight at three times the rate of controls. They exhibited reduced conception rates, increased peripartum pup mortality, and impaired lactogenesis. The impairment of lactogenesis involved lipid accumulation in the secretory epithelial cells indicative of an absence of copius milk secretion. Expression of mRNAs for -casein, whey acid protein, and -lactalbumin were all decreased immediately postpartum but recovered as lactation was established over 2–3 days. Expression of acetyl-CoA carboxylase (ACC)- mRNA was also decreased at parturition as was the total enzyme activity, although there was a compensatory increase in the proportion in the active state. By day 10 of lactation, the proportion of ACC in the active state was also decreased in obese animals, indicative of suppression of de novo fatty acid synthesis resulting from the supply of preformed fatty acids in the diet. Although obese animals consumed more calories in the nonpregnant and early pregnant states, they showed a marked depression in fat intake around day 9 of pregnancy before food intake recovered in later pregnancy. Food intake increased dramatically in both lean and obese animals during lactation although total calories consumed were identical in both groups. Thus, despite access to high-energy diets, the obese animals mobilized even more adipose tissue during lactation than their lean counterparts. Obese animals also exhibited marked abnormalities in alveolar development of the mammary gland, which may partially explain the delay in differentiation evident during lactogenesis

    Critical behaviour of SU(2) lattice gauge theory. A complete analysis with the χ2\chi^2-method

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    We determine the critical point and the ratios β/ν\beta/\nu and γ/ν\gamma/\nu of critical exponents of the deconfinement transition in SU(2)SU(2) gauge theory by applying the χ2\chi^2-method to Monte Carlo data of the modulus and the square of the Polyakov loop. With the same technique we find from the Binder cumulant grg_r its universal value at the critical point in the thermodynamical limit to 1.403(16)-1.403(16) and for the next-to-leading exponent ω=1±0.1\omega=1\pm0.1. From the derivatives of the Polyakov loop dependent quantities we estimate then 1/ν1/\nu. The result from the derivative of grg_r is 1/ν=0.63±0.011/\nu=0.63\pm0.01, in complete agreement with that of the 3d3d Ising model.Comment: 11 pages, 3 Postscript figures, uses Plain Te

    Density Matrix Renormalization Group Study of the Disorder Line in the Quantum ANNNI Model

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    We apply Density Matrix Renormalization Group methods to study the phase diagram of the quantum ANNNI model in the region of low frustration where the ferromagnetic coupling is larger than the next-nearest-neighbor antiferromagnetic one. By Finite Size Scaling on lattices with up to 80 sites we locate precisely the transition line from the ferromagnetic phase to a paramagnetic phase without spatial modulation. We then measure and analyze the spin-spin correlation function in order to determine the disorder transition line where a modulation appears. We give strong numerical support to the conjecture that the Peschel-Emery one-dimensional line actually coincides with the disorder line. We also show that the critical exponent governing the vanishing of the modulation parameter at the disorder transition is βq=1/2\beta_q = 1/2.Comment: 4 pages, 5 eps figure
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