1,062 research outputs found

    ON THE LONGITUDINAL CHARGE RESPONSE IN THE QUASI ELASTIC PEAK REGION

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    We generalise our theory for the linear response function in the quasi elastic peak region to the case N ≠ Z and apply it to the recently measured e,e' cross-section of 238U. We find that the problem of the missing charge persists

    Some comments on nˉp\bar n p-annihilation branching ratios into ππ\pi \pi-, KˉK\bar K K- and πη\pi \eta-channels

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    We give some remarks on the nˉp\bar n p-partial branching ratios in flight at low momenta of antineutron, measured by OBELIX collaboration. The comparison is made to the known branching ratios from the ppˉp \bar p-atomic states. The branching ratio for the reaction nˉpπ+π0\bar n p \to \pi^+\pi^0 is found to be suppressed in comparison to what follows from the ppˉ p \bar p-data. It is also shown, that there is no so called dynamic I=0-amplitude suppression for the process NNˉKKˉN\bar N \to K\bar K.Comment: 8 pages, LaTeX, no figure

    Mapping the aerosol over Eurasia from the Zotino Tall Tower

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    The present study covers more than 5 yr corresponding to more than 40 000 hours of particle and gas data measured at the Siberian tall tower Zotino Tall Tower (ZOTTO) (60.8%26deg%3BN; 89.35%26deg%3BE). Extrapolated along 10-d back trajectories, the ZOTTO measurements cover large parts of the Eurasian land mass. Mapping the extrapolated ZOTTO data points to major anthropogenic source regions and Siberian fire regions, consistent with emission data for CO and vegetation fires. Middle East mid-latitude sources stand out strongly and possibly emissions from Northern China may be seen at times from ZOTTO. The maps of measured light scattering and absorption characteristics support the interpretation of different source types. Three clusters of substantially different submicrometer particle size distributions were found, the maps of which also could be related to major aerosol source regions

    Асинхронный электропривод механизма передвижения козлового крана

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    Объектом исследования является электропривод двухдвигательный механизма козлового крана его передвижения. В процессе работы провели исследования электропривода двухдвигательного частотно-регулируемого. По результатам исследования была обоснована адекватность имитационных моделей, так же получены параметры настройки данной системы которая обеспечивает синхронизации скоростей при работе вращения двух приводов и при изменении нагрузки.Object of investigation is electric drive of two-motor mechanism of goat crane of its movement. In the process of operation, studies of electric drive of two-engine frequency-controlled were carried out. Based on the results of the study, the adequacy of simulation models was justified, as well as settings of this system were obtained, which provides synchronization of speeds during operation of rotation of two drives and at change of loa

    Momentum-Dependent Mean Field Based Upon the Dirac-Brueckner Approach for Nuclear Matter

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    A momentum-dependent mean field potential, suitable for application in the transport-model description of nucleus-nucleus collisions, is derived in a microscopic way. The derivation is based upon the Bonn meson-exchange model for the nucleon-nucleon interaction and the Dirac-Brueckner approach for nuclear matter. The properties of the microscopic mean field are examined and compared with phenomenological parametrizations which are commonly used in transport-model calculations.Comment: 15 pages text (RevTex) and 4 figures (postscript in a separate uuencoded file), UI-NTH-930

    Turbulent thermal diffusion in a multi-fan turbulence generator with the imposed mean temperature gradient

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    We studied experimentally the effect of turbulent thermal diffusion in a multi-fan turbulence generator which produces a nearly homogeneous and isotropic flow with a small mean velocity. Using Particle Image Velocimetry and Image Processing techniques we showed that in a turbulent flow with an imposed mean vertical temperature gradient (stably stratified flow) particles accumulate in the regions with the mean temperature minimum. These experiments detected the effect of turbulent thermal diffusion in a multi-fan turbulence generator for relatively high Reynolds numbers. The experimental results are in compliance with the results of the previous experimental studies of turbulent thermal diffusion in oscillating grids turbulence (Buchholz et al. 2004; Eidelman et al. 2004). We demonstrated that turbulent thermal diffusion is an universal phenomenon. It occurs independently of the method of turbulence generation, and the qualitative behavior of particle spatial distribution in these very different turbulent flows is similar. Competition between turbulent fluxes caused by turbulent thermal diffusion and turbulent diffusion determines the formation of particle inhomogeneities.Comment: 9 pages, 9 figure, REVTEX4, Experiments in Fluids, in pres

    On the Divergence of Perturbation Theory. Steps Towards a Convergent Series

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    The mechanism underlying the divergence of perturbation theory is exposed. This is done through a detailed study of the violation of the hypothesis of the Dominated Convergence Theorem of Lebesgue using familiar techniques of Quantum Field Theory. That theorem governs the validity (or lack of it) of the formal manipulations done to generate the perturbative series in the functional integral formalism. The aspects of the perturbative series that need to be modified to obtain a convergent series are presented. Useful tools for a practical implementation of these modifications are developed. Some resummation methods are analyzed in the light of the above mentioned mechanism.Comment: 42 pages, Latex, 4 figure
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