50 research outputs found

    Orbital forcings of the Earth?s climate in wavelet domain

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    International audienceWe examine two paleoclimate proxy records ? the temperature differences from the Antarctic Vostok ice core and the composite ?18O record from three sites (V19-30, ODP 677, and ODP 846) ? in order to search for indications of orbital forcings. We demonstrate that the non-decimated wavelet transform is an appropriate tool for investigating temporarily changing spectral properties of records. Our results indicate that abrupt climate warmings with cyclicity of ~100 kiloyears during the last 400 kiloyears were caused by the combined unidirectional influences of three orbital parameters and the eccentricity can be considered as a modulator defining transitions from the Ice Ages to the periods of comparative warmings. Non-decimated wavelet transform avails discovering the possible part played in climate change by the eccentricity-forced variations. Up to approximately 1.7 million years BP, the influence of this variations of eccentricity appears in increasing for almost all local maxima of ?18O. Since the ~1.7 million years BP, minor and significant maxima alternated and this not affected as much the variations of ?18O

    Fukushima plutonium effect and blow-up regimes in neutron-multiplying media

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    It is shown that the capture and fission cross-sections of 238U and 239Pu increase with temperature within 1000-3000 K range, in contrast to those of 235U, that under certain conditions may lead to the so-called blow-up modes, stimulating the anomalous neutron flux and nuclear fuel temperature growth. Some features of the blow-up regimes in neutron-multiplying media are discussed.Comment: 15 pages, 8 figures. (v2: numerous corrections and style improvements). arXiv admin note: substantial text overlap with arXiv:1207.369

    On some fundamental peculiarities of the traveling wave reactor

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    On the basis of the condition for nuclear burning wave existence in the neutron-multiplicating media (U-Pu and Th-U cycles) we show the possibility of surmounting the so-called dpa-parameter problem, and suggest an algorithm of the optimal nuclear burning wave mode adjustment, which is supposed to yield the wave parameters (fluence/neutron flux, width and speed of nuclear burning wave) that satisfy the dpa-condition associated with the tolerable level of the reactor materials radioactive stability, in particular that of the cladding materials. It is shown for the first time that the capture and fission cross-sections of 238^{238}U and 239^{239}Pu increase with temperature within 1000-3000K range, which under certain conditions may lead to a global loss of the nuclear burning wave stability. Some variants of the possible stability loss due to the so-called blow-up modes (anomalous nuclear fuel temperature and neutron flow evolution) are discussed and are found to possibly become a reason for a trivial violation of the traveling wave reactor internal safety.Comment: 44 pages, 19 figures, 2 table

    Mechanism of Deep-focus Earthquakes Anomalous Statistics

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    Analyzing the NEIC-data we have shown that the spatial deep-focus earthquake distribution in the Earth interior over the 1993-2006 is characterized by the clearly defined periodical fine discrete structure with period L=50 km, which is solely generated by earthquakes with magnitude M 3.9 to 5.3 and only on the convergent boundary of plates. To describe the formation of this structure we used the model of complex systems by A. Volynskii and S. Bazhenov. The key property of this model consists in the presence of a rigid coating on a soft substratum. It is shown that in subduction processes the role of a rigid coating plays the slab substance (lithosphere) and the upper mantle acts as a soft substratum. Within the framework of this model we have obtained the estimation of average values of stress in the upper mantle and Young's modulus for the oceanic slab (lithosphere) and upper mantle.Comment: 9 pages, 7 figure

    Damage to extreme-ultraviolet Sc/Si multilayer mirrors exposed to intense 46.9-nm laser pulses

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    Includes bibliographical references (page 622).The damage threshold and damage mechanism of extreme-ultraviolet Sc/Si multilayer mirror coatings are investigated with focused nanosecond pulses at 46.9-nm radiation from a compact capillary-discharge laser. Damage threshold fluences of ~0.08 J/cm2 are measured for coatings deposited on both borosilicate glass and Si substrates. The use of scanning and transmission electron microscopy and small-angle x-ray diffraction techniques reveals the thermal nature of the damage mechanism. The results are relevant to the use of newly developed high-flux extreme-ultraviolet sources in applications

    KamLAND-experiment and Soliton-like Nuclear Georeactor. Part 1. Comparison of Theory with Experiment

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    We give an alternative description of the data produced in the KamLAND experiment, assuming the existence of a natural nuclear reactor on the boundary of the liquid and solid phases of the Earth's core. Analyzing the uncertainty of antineutrino spectrum of georeactor origin, we show that the theoretical (which takes into account the soliton-like nuclear georeactor) total reactor antineutrino spectra describe with good accuracy the experimental KamLAND-data over the years of 2002-2007 and 2002-2009, respectively. At the same time the parameters of mixing ({\Delta}(m21)^2=2.5\cdot 10^-5 eV^2, tan^2{\theta}12=0.437) calculated within the framework of georeactor hypothesis substantially differ from the parameters of mixing ({\Delta}(m21)^2=7.49\cdot 10^-5 eV^2, tan^2{\theta}12=0.436) obtained in KamLAND-experiment for total exposure over the period of 2002-2009. By traingulation of KamLAND and Borexino data we have constructed the coordinate location of soliton-like nuclear georeactors on the boundary of the liquid and solid phases of the Earth core. Based on the necessary condition of full synchronization of geological (magnetic) time scale and time evolution of heat power of nuclear georeactor, which plays the role of energy source of the Earth magnetic field, and also the strong negative correlation between magnetic field of the solar tachocline zone and magnetic field of the Earth liquid core (Y-component) we have obtain the estimation of nuclear georeactor average heat power ~30 TW over the years 2002-2009.Comment: 50 pages; 17 figures; 1 table. A substantially revised, corrected and enhanced editio

    Air plasma sprayed coatings of self-fluxing powder materials

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    © Published under licence by IOP Publishing Ltd. The article discusses the structural features of self-fluxing coatings obtained by plasma spraying air from entering the hub ring and the gas-dynamic focusing powder. It was shown that, unlike the unilateral spot powder inlet into the plasma jet, the use of the annular input node allows to increase heating efficiency and to accelerate the particles in the plasma stream. By optical and scanning electron microscopy that most of the particles forming the coating, in the plasma jet is in a molten or plasticized condition. Transmission electron microscopy revealed that high cooling rates of such particles contribute to the formation of γ-SMC supersaturated solid solution Ni-based average grain size of 80 nm

    The peculiarities of cross-correlation between two secondary precursors - radon and magnetic field variations, induced by stress transfer changes

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    A model of precursor manifestation mechanisms, stimulated by tectonic activity and some peculiarities of observer strategy, whose main task is the effective measurement of precursors in the spatial area of their occurrence on the Earth's daylight, are considered. In particular, the applicability of Dobrovolsky's approximation is analyzed, when an unperturbed medium (characterized by the simple shear state) and the area of tectonic activity (local inhomogeneity caused by the change only of shear modulus) are linearly elastic, and perturbation, in particular, surface displacement is calculated as a difference of the solutions of two independent static problems of the theory of elasticity with the same boundary condition on the surface. Within the framework of this approximation a formula for the spatial distribution (of first component) of magnetic field variations caused by piezomagnetic effect in the case of perturbed regular medium, which is in simple shear state is derived. Cogent arguments in favor of linear dependence between the radon spatial distribution and conditional deformation are obtained. Changes in magnetic field strength and radon concentrations were measured along a tectonomagnetic profile of the total length of 11 km in the surroundings of the "Academician Vernadsky" Station on the Antarctic Peninsula (W 64{\deg}16', S 65{\deg}15'). Results showed a positive correlation between the annual surface radon concentration and annual changes of magnetic field relative to a base point, and also the good coincidence with theoretical calculation.Comment: 27 pages, 11 figures, 3 tables (a substantially revised and extended edition; v3 -- some analysis of recent publications added
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