53 research outputs found
Can disorder induce a finite thermal conductivity in 1D lattices?
We study heat conduction in one dimensional mass disordered harmonic and
anharmonic lattices. It is found that the thermal conductivity of the
disordered anharmonic lattice is finite at low temperature, whereas it diverges
as 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
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
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
, and 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
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
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 model: Boundary Jumps, Fourier's Law and Scaling
We examine the interplay of surface and volume effects in systems undergoing
heat flow. In particular, we compute the thermal conductivity in the FPU
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
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 (x ≤ 0.1)
Magnetic field dependences of the Hall coefficient and resistivity have been studied in detail for dilute magnetic compounds (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 ≈ 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 properties is developed on the basis of spin-polaron approach, Pauli paramagnetism and the density of states renormalization effects at low temperatures
- …