41,830 research outputs found

    Sensitivity design technique for optimal control, part C Final report

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    Optimal sensitivity design techniques to design feedback control system for large, flexible booste

    Slow X-ray bursts and chromospheric flares with filament disruption

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    The data from OGO-5 and OSO-7 X-ray experiments have been analyzed to study six chromospheric flares with filament disruption associated with slow thermal X-ray bursts. Filament activation accompanied by a slight X-ray enhancement precedes the first evidence of H alpha flare by a few minutes. Rapid increase of the soft X-ray flux is accompanied by a sudden brightening of the filament when viewed on-band H alpha. Thereafter the bright chromospheric strands reach their maximum brightness with maximum X-ray flux. Any plateau or slow decay phase in the X-ray flux is accompanied by a quieting in filament activity and even by filament re-appearance. The height of the disrupted prominence is proportional to the soft X-ray flux for the August 3, 1970 limb occulted event

    Dissociation energy and long-range potential of diatomic molecules from vibrational spacings - The halogens

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    Dissociation energy and long-range potential of diatomic molecules from vibrational spacings, halogen

    Shape resonances and rotationally predissociating levels - The atomic collision time delay functions and quasibound level properties of H2 /Chi /1 Sigma g plus//

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    Atomic collision time delay functions and quasibound level properties of ground state of molecular hydroge

    X-ray bursts from solar flares behind the limb

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    X-ray bursts are identified from the UCSD OSO-7 X-ray experiment data. X-ray spectroheliograms of OSO-5, H alpha activity at the limb, and the emergence and disappearance of sunspot groups at the limb were studied and 17 active centers were found as likely seats of the X-ray bursts beyond the limb. The analysis of 37 X-ray bursts and their physical parameters is presented. Results show that (1) the distributions of maximum temperature, maximum emission measure, and characteristic cooling time of the over-the-limb events do not significantly differ from those of disk events; (2) that radiation is the dominant cooling mechanism for the hot flare plasma; and (3) that the scale height for X-ray emission in the 5-10 keV range is large. Observations show that the fraction of soft X-ray bursts which have a nonthermal component is the same on and off of the disk. Hard X-ray emission over extended regions is indicated

    The pion-pion scattering amplitude. III: Improving the analysis with forward dispersion relations and Roy equations

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    We complete and improve the fits to experimental ππ\pi\pi scattering amplitudes, both at low and high energies, that we performed in the previous papers of this series. We then verify that the corresponding amplitudes satisfy analyticity requirements, in the form of partial wave analyticity at low energies, forward dispersion relations (FDR) at all energies, and Roy equations belowKˉK\bar{K}K threshold; the first by construction, the last two, inside experimental errors. Then we repeat the fits including as constraints FDR and Roy equations. The ensuing central values of the various scattering amplitudes verify very accurately FDR and, especially, Roy equations, and change very little from what we found by just fitting data, with the exception of the D2 wave phase shift, for which one parameter moves by 1.5σ1.5 \sigma. These improved parametrizations therefore provide a reliable representation of pion-pion amplitudes with which one can test various physical relations. We also present a list of low energy parameters and other observables. In particular, we find a0(0)=0.223±0.009Mπ−1a_0^{(0)}=0.223\pm0.009 M^{-1}_\pi, a0(2)=−0.0444±0.0045Mπ−1a_0^{(2)}=-0.0444\pm0.0045 M^{-1}_\pi and δ0(0)(mK2)−δ0(2)(mK2)=50.9±1.2o\delta_0^{(0)}(m^2_K)-\delta_0^{(2)}(m^2_K)=50.9\pm1.2^{\rm o}.Comment: Plain TeX. 29 figures. Version to be published in PRD, with improved P and F wave
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