11,402 research outputs found

    Flat conductor cable survey

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    Design handbook contains data and illustrations concerned with commercial and Government flat-conductor-cable connecting and terminating hardware. Material was obtained from a NASA-sponsored industry-wide survey of approximately 150 companies and Government agencies

    A linearized kinetic theory of spin-1/2 particles in magnetized plasmas

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    We have considered linear kinetic theory including the electron spin properties in a magnetized plasma. The starting point is a mean field Vlasov-like equation, derived from a fully quantum mechanical treatment, where effects from the electron spin precession and the magnetic dipole force is taken into account. The general conductivity tensor is derived, including both the free current contribution, as well as the magnetization current associated with the spin contribution. We conclude the paper with an extensive discussion of the quantum-mechanical boundary where we list parameter conditions that must be satisfied for various quantum effects to be influential.Comment: 11 page

    Applications of FEM and BEM in two-dimensional fracture mechanics problems

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    A comparison of the finite element method (FEM) and boundary element method (BEM) for the solution of two-dimensional plane strain problems in fracture mechanics is presented in this paper. Stress intensity factors (SIF's) were calculated using both methods for elastic plates with either a single-edge crack or an inclined-edge crack. In particular, two currently available programs, ANSYS for finite element analysis and BEASY for boundary element analysis, were used

    Frame synchronization performance and analysis

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    The analysis used to generate the theoretical models showing the performance of the frame synchronizer is described for various frame lengths and marker lengths at various signal to noise ratios and bit error tolerances

    Conductivity in Jurkat cell suspension after ultrashort electric pulsing

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    Ultrashort electric pulses applied to similar cell lines such as Jurkat and HL-60 cells can produce markedly different results , which have been documented extensively over the last few years. We now report changes in electrical conductivity of Jurkat cells subjected to traditional electroporation pulses (50 ms pulse length) and ultrashort pulses (10 ns pulse length) using time domain dielectric spectroscopy (TDS). A single 10 ns, 150 kV/cm pulse did not noticeably alter suspension conductivity while a 50 ms, 2.12 kV/cm pulse with the same energy caused an appreciable conductivity rise. These results support the hypothesis that electroporation pulses primarily interact with the cell membrane and cause conductivity rises due to ion transport from the cell to the external media, while pulses with nanosecond duration primarily interact with the membranes of intracellular organelles. However, multiple ultrashort pulses have a cumulative effect on the plasma membrane, with five pulses causing a gradual rise in conductivity up to ten minutes post-pulsing

    Preliminary design characteristics of a subsonic business jet concept employing an aspect ratio 25 strut braced wing

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    The advantages of replacing the conventional wing on a transatlantic business jet with a larger, strut braced wing of aspect ratio 25 were evaluated. The lifting struts reduce both the induced drag and structural weight of the heavier, high aspect ratio wing. Compared to the conventional airplane, the strut braced wing design offers significantly higher lift to drag ratios achieved at higher lift coefficients and, consequently, a combination of lower speeds and higher altitudes. The strut braced wing airplane provides fuel savings with an attendant increase in construction costs

    Inflation Assisted by Heterotic Axions

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    We explore the possibility of obtaining inflation in weakly coupled heterotic string theory, where the model dependent axions are responsible for driving inflation. This model can be considered as a certain extrapolation of m2ϕ2m^{2}\phi^{2}-inflation, and is an attempt to explicitly realize the so called N-flation proposal in string theory. The instanton generated potential for the axions essentially has two parameters; a natural mass scale MM and the string coupling gsg_{s}. For isotropic compactifications leading to of order O(104)\mathcal{O} (10^4) axions in the four dimensional spectrum we find that with (M,gs)≃(MGUT,0.5)(M, g_{s})\simeq(M_{GUT}, 0.5) the observed temperature fluctuations in the CMB are correctly reproduced. We assume an initially random distribution for the vevs of the axions. The spectral index, nsn_{s}, is generically more red than for m2ϕ2m^{2}\phi^{2}-inflation. The greater the vevs, the more red the spectral index becomes. Allowing for a wide range of vevs 55 ee-foldings from the end of inflation, we find 0.946â‰Čnsâ‰Č0.9620.946\lesssim n_{s} \lesssim 0.962. The tensor-to-scalar ratio, rr, is more sensitive to the vevs, but typically smaller than in m2ϕ2m^{2}\phi^{2}-inflation. Furthermore, in the regime where the leading order theory is valid, rr is bounded by r<0.10r < 0.10. The spectral index and the tensor-to-scalar ratio are correlated. For example, ns≃0.951n_{s}\simeq 0.951 corresponds to r≃0.036r\simeq 0.036.Comment: 1+21 pages, 2 figures, v2: Typos corrected, v3: Typos, very minor corrections, reference added, to appear in JCA

    Effects of the gg-factor in semi-classical kinetic plasma theory

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    A kinetic theory for spin plasmas is put forward, generalizing those of previous authors. In the model, the ordinary phase space is extended to include the spin degrees of freedom. Together with Maxwell's equations, the system is shown to be energy conserving. Analysing the linear properties, it is found that new types of wave-particle resonances are possible, that depend directly on the anomalous magnetic moment of the electron. As a result new wave modes, not present in the absence of spin, appear. The implications of our results are discussed.Comment: 4 pages, two figures, version to appear in Physical Review Letter

    Energy management study for lunar oxygen production

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    Energy management opportunities in the process of hydrogen reduction of ilmenite for lunar oxygen production are being investigated. An optimal energy system to supply the power requirements for the process will be determined

    Circular 64

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    Treatment of Alaska-produced food products by ionizing radiation may benefit the seafood and agricultural industries and the Alaskan consumer. A feasibility study to evaluate the potential social and economic benefits and risks as well as the costs of using the process in Alaska on Alaskan products is being coordinated by the Institute of Northern Engineering. A research and development project to determine effects on the quality o f Alaskan products could be the next phase in the introduction o f a new food-preservation technique to Alaska
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