880 research outputs found

    Classical Oscilators in General Relativity

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    It is shown that in general relativity some static metrics are able to simulate oscillatory motions. Their form depends on two arbitrary real parameters which determine the specific oscillation modes. The conclusion is that these metrics can be used for new geometric models of closed or even open bags. Pacs: 04.02.-q and 04.02.JbComment: Latex, 10 page

    Fractional Curve Flows and Solitonic Hierarchies in Gravity and Geometric Mechanics

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    Methods from the geometry of nonholonomic manifolds and Lagrange-Finsler spaces are applied in fractional calculus with Caputo derivatives and for elaborating models of fractional gravity and fractional Lagrange mechanics. The geometric data for such models are encoded into (fractional) bi-Hamiltonian structures and associated solitonic hierarchies. The constructions yield horizontal/vertical pairs of fractional vector sine-Gordon equations and fractional vector mKdV equations when the hierarchies for corresponding curve fractional flows are described in explicit forms by fractional wave maps and analogs of Schrodinger maps.Comment: latex2e, 11pt, 21 pages; the variant accepted to J. Math. Phys.; new and up--dated reference

    Extraction of reliable information from time-domain pressure and flow signals measured by means of forced oscillation techniques

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    This paper aims to give a proof-of-concept for the possible application of the forced oscillation lung function test to assess the viscoelastic properties of the airways and tissue. In particular, a novel signal processing algorithm is employed on non-stationary, noisy, (relatively) short time series of respiratory pressure and flow signals. This novel technique is employed to filter the useful information from the signals acquired under two measurement conditions: pseudo-functional residual capacity (PFRC) and pseudo-total lung capacity (PTLC). The PFRC is the measurement performed at lowest lung volume with maximum deflation, and the PTLC is measurement performed at the maximum lung volume under maximum inflation. The results suggest that the proposed technique is able to extract information on the viscoelastic properties of the lung tissue at a macroscopic level. The conclusion of this preliminary study is that the proposed combination of signal processing method and lung function test is suited to be employed on a large database in order to deliver reference values and perform further statistical analysis

    CONSIDERATIONS REGARDING THE USE OF EQUIPMENT FOR THE ESTABLISHMENT OF WATER COLLECTION BASINS FROM PRECIPITATION AND FROM THE USE OF SPRAY IRRIGATION SYSTEMS

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    Global warming has been growing rapidly lately, which implies an increasing need for water for the good development of agricultural crops. To allow the recovery of a significant amount of water from rainfall or irrigation, reducing the amount of energy necessary for irrigation but also for soil losses caused by the phenomenon of erosion or puddling, works are introduced in crop technologies with the help of which this recovery can be achieved. This paper presents equipment used for the execution of rainwater catchment basins and the use of sprinkler irrigation systems
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