53 research outputs found

    Can disorder induce a finite thermal conductivity in 1D lattices?

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    We study heat conduction in one dimensional mass disordered harmonic and anharmonic lattices. It is found that the thermal conductivity κ\kappa of the disordered anharmonic lattice is finite at low temperature, whereas it diverges as κN0.43\kappa \sim N^{0.43} at high temperature. Moreover, we demonstrate that a unique nonequilibrium stationary state in the disordered harmonic lattice does not exist at all.Comment: 4 pages with 4 eps figure

    Continuous selections of multivalued mappings

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    This survey covers in our opinion the most important results in the theory of continuous selections of multivalued mappings (approximately) from 2002 through 2012. It extends and continues our previous such survey which appeared in Recent Progress in General Topology, II, which was published in 2002. In comparison, our present survey considers more restricted and specific areas of mathematics. Note that we do not consider the theory of selectors (i.e. continuous choices of elements from subsets of topological spaces) since this topics is covered by another survey in this volume

    Wave transmission, phonon localization and heat conduction of 1D Frenkel-Kontorova chain

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    We study the transmission coefficient of a plane wave through a 1D finite quasi-periodic system -- the Frenkel-Kontorova (FK) model -- embedding in an infinite uniform harmonic chain. By varying the mass of atoms in the infinite uniform chain, we obtain the transmission coefficients for {\it all} eigenfrequencies. The phonon localization of the incommensurated FK chain is also studied in terms of the transmission coefficients and the Thouless exponents. Moreover, the heat conduction of Rubin-Greer-like model for FK chain at low temperature is calculated. It is found that the stationary heat flux J(N)NαJ(N)\sim N^{\alpha}, and α\alpha depends on the strength of the external potential.Comment: 15 pages in Revtex, 8 EPS figure

    Recent Developments of NEMO: Detection of Solar Eruptions Characteristics

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    The recent developments in space instrumentation for solar observations and telemetry have caused the necessity of advanced pattern recognition tools for the different classes of solar events. The Extreme ultraviolet Imaging Telescope (EIT) of solar corona on-board SOHO spacecraft has uncovered a new class of eruptive events which are often identified as signatures of Coronal Mass Ejection (CME) initiations on solar disk. It is evident that a crucial task is the development of an automatic detection tool of CMEs precursors. The Novel EIT wave Machine Observing (NEMO) (http://sidc.be/nemo) code is an operational tool that detects automatically solar eruptions using EIT image sequences. NEMO applies techniques based on the general statistical properties of the underlying physical mechanisms of eruptive events on the solar disc. In this work, the most recent updates of NEMO code - that have resulted to the increase of the recognition efficiency of solar eruptions linked to CMEs - are presented. These updates provide calculations of the surface of the dimming region, implement novel clustering technique for the dimmings and set new criteria to flag the eruptive dimmings based on their complex characteristics. The efficiency of NEMO has been increased significantly resulting to the extraction of dimmings observed near the solar limb and to the detection of small-scale events as well. As a consequence, the detection efficiency of CMEs precursors and the forecasts of CMEs have been drastically improved. Furthermore, the catalogues of solar eruptive events that can be constructed by NEMO may include larger number of physical parameters associated to the dimming regions.Comment: 12 Pages, 5 figures, submitted to Solar Physic

    Fractional Variations for Dynamical Systems: Hamilton and Lagrange Approaches

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    Fractional generalization of an exterior derivative for calculus of variations is defined. The Hamilton and Lagrange approaches are considered. Fractional Hamilton and Euler-Lagrange equations are derived. Fractional equations of motion are obtained by fractional variation of Lagrangian and Hamiltonian that have only integer derivatives.Comment: 21 pages, LaTe

    FPU β\beta model: Boundary Jumps, Fourier's Law and Scaling

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    We examine the interplay of surface and volume effects in systems undergoing heat flow. In particular, we compute the thermal conductivity in the FPU β\beta model as a function of temperature and lattice size, and scaling arguments are used to provide analytic guidance. From this we show that boundary temperature jumps can be quantitatively understood, and that they play an important role in determining the dynamics of the system, relating soliton dynamics, kinetic theory and Fourier transport.Comment: 5pages, 5 figure

    ЭКСПЕДИЦИОННЫЕ РАДИОЭКОЛОГИЧЕСКИЕ ИССЛЕДОВАНИЯ В ЯПОНСКОМ МОРЕ И СЕВЕРО-ЗАПАДНОЙ ЧАСТИ ТИХОГО ОКЕАНА ПОСЛЕ АВАРИИ НА ЯПОНСКОЙ АЭС «ФУКУСИМА-1»: ПРЕДВАРИТЕЛЬНЫЕ РЕЗУЛЬТАТЫ

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    In the period from April 22 until May 20, 2011, an expedition aboard the research vessel “Pavel Gordienko” (Russian Federation) was carried out to the Sea of Japan and the Kuril-Kamchatka region of the Pacific Ocean. The main aim of the expedition was to study radioactive contamination of the atmospheric air and sea water after the accident at the NPP “Fukushima-1” in Japan. This paper provides preliminary results on the activity concentration of 137Cs and 134Cs in twenty four samples of sea water. The activity concentrations of 131I, 137Cs, 134Cs, and 7Be for twenty nine samples of atmospheric aerosols, which were sampled during the expedition, are also given. Despite the preliminary character of the results of this study, a generic conclusion on a negligible radiological impact of the anthropogenic gamma-ray-emitting radionuclides for the Far-Eastern sea areas of Russia can be reached. The investigations have been supported by a grant from the Russian Geographical Society.В период с 22 апреля по 20 мая 2011 г. на научно-исследовательском судне «Павел Гордиенко» (Российская Федерация) было проведено экспедиционное обследование Японского моря и Курило-Камчатского района Тихого океана. Основной целью экспедиции являлось исследование радиоактивного загрязнения воздушной и водной среды после аварии на АЭС «Фукусима-1» в Японии. В данной статье представлены предварительные результаты оценки содержания 137Cs и 134Cs в двадцати четырех пробах морской воды. Кроме этого, даны результаты определения содержания 131I, 137Cs, 134Cs, и 7Be в двадцати девяти пробах атмосферных аэрозолей, отобранных в рейсе. Несмотря на предварительный характер полученных результатов, проведенные исследования позволяют прийти к общему заключению о пренебрежимо малом влиянии изученных техногенных гамма-излучающих радионуклидов на радиационную обстановку в районах российского побережья Дальнего Востока. Грант на проведение исследований был выделен Попечительским советом Русского географического общества

    Magnetic Field Enhancement of the Hall Effect in Dilute Magnetic System La1xCexB6La_{1 - x}Ce_{x}B_6 (x ≤ 0.1)

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    Magnetic field dependences of the Hall coefficient RHR_{H} and resistivity have been studied in detail for dilute magnetic compounds La1xCexB6La_{1-x}Ce_{x}B_6 (x ≤ 0.1) at temperatures 1.8-300 K. It was established that the regime of weak localization of charge carriers, which was observed in these heavy fermion systems below 30 K destroys gradually in magnetic field up to 8 T. Moreover, in addition to the strong negative magnetoresistance (Δρ/ρ ≈ 80%) a drastic enhancement of the negative Hall coefficient in magnetic field (Δ RH//RHR_{H}//R_{H} ≈ 50%) has been deduced at liquid helium temperatures. The results of comprehensive analysis contradict the predictions of Kondo-impurity approach for this archetypal strongly correlated electron system in the dilute impurity limit. An alternative interpretation of La1xCexB6La_{1-x}Ce_{x}B_6 properties is developed on the basis of spin-polaron approach, Pauli paramagnetism and the density of states renormalization effects at low temperatures
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