223 research outputs found
On the radiative heat exchange between spherical particles at small distances
Radiative heat exchange of spherical particles is recalculated in the
framework of fluctuation electrodynamics using the dipole approximation. We
show that correct numerical coefficient in the resulting integral expression
equals 4/pi, in contrast with that obtained by other authors.Comment: 3 page
Features of the fluctuation -electromagnetic interaction between a small conducting particle and polarizable medium
For the first time, new important features of the fluctuation electromagnetic
interaction between a small conducting particle and a smooth surface of
polarizable medium (both dielectric and metallic) are worked out. The particle
is characterized by classical electric and magnetic polarizabilities. The
temperature dependence and retardation effects are explicitly taken into
account. The resulting interaction force between a metallic particle and the
surface of metal proves to be determined to great extent by magnetic coupling
and reveals specific dependences on distance, temperature, particle radius and
material properties of contacting materials. Numerical estimations are given in
the case of a Cu particle above a smooth Cu substrate at different particle
radius and temperature of the system.Comment: 13 pages, 5 figure
Geosituational modelling of coastal marine systems
The article summarizes years of experience of geosituational modelling of coastal marine systems in the Baltic Sea region and adjacent territories. Kaliningrad universities and academic institutions have done extensive research on the diversity of approaches and models of the regional geosituations as well as on identifying the most promising coastal marine areas. Some of the models presented in the present paper are qualitative, while others are empirical and statistical ones. However, the majority of the models can be referred to as forms of graphic and image mapping. The significance of the regional models lies in their specificity, a more detailed character (compared to the generalist ones) and the possibility of using them to back up managerial decisions in critical and emergency situations in order to minimize the negative effects of natural (storms, floods, earthquakes, etc.) and anthropogenic emergency situations. The authors developed a matrix classification attributable to a particular class of models for the situations leading to uncertain outcomes. The authors suggest using numerical methods combined with the empirical and statistical models for the assessment of the impact of industrial fishing on marine environment, minimizing the consequences of storms, floods and others factors. Special attention is paid to the modelling of climate change and geo-ecological consequences, as well as to atlas mapping and landscape planning. As a result of the geosituational analysis the authors got new insights into the solar-terrestrial links, marine-terrestrial ecosystems, global and regional processes related to climate change, oceanization, the vulnerability of natural systems under the increasing pressure of anthropogenic activities, and continuously increasing risks presented by industrial agriculture and other types of land use
An Artificially Lattice Mismatched Graphene/Metal Interface: Graphene/Ni/Ir(111)
We report the structural and electronic properties of an artificial
graphene/Ni(111) system obtained by the intercalation of a monoatomic layer of
Ni in graphene/Ir(111). Upon intercalation, Ni grows epitaxially on Ir(111),
resulting in a lattice mismatched graphene/Ni system. By performing Scanning
Tunneling Microscopy (STM) measurements and Density Functional Theory (DFT)
calculations, we show that the intercalated Ni layer leads to a pronounced
buckling of the graphene film. At the same time an enhanced interaction is
measured by Angle-Resolved Photo-Emission Spectroscopy (ARPES), showing a clear
transition from a nearly-undisturbed to a strongly-hybridized graphene
-band. A comparison of the intercalation-like graphene system with flat
graphene on bulk Ni(111), and mildly corrugated graphene on Ir(111), allows to
disentangle the two key properties which lead to the observed increased
interaction, namely lattice matching and electronic interaction. Although the
latter determines the strength of the hybridization, we find an important
influence of the local carbon configuration resulting from the lattice
mismatch.Comment: 9 pages, 3 figures, Accepted for publication in Phys. Rev.
Recent denudation of the Earth's plains according to data on sediment and dissolved substance load
Quantity of mechanical and chemical denudation, estimated on the load of suspended sediments and dissolved subtance are examined. The role of zonal and non-zonal factors (relief, rocks, human activity) in spatial changes of these types of denudation is fixed. Spatial variability of denudation has a complicated structure and in different natural-anthropogenic conditions repeatedly reacts on chages of controlling it factors. Maximums, connected with highly mastered regions of temperate belt and subtropics-tropics regions are revealed. © 2005 A.P. Dedkov, V.I. Moszherin, A.N. Sharifullin, P.P. Denmukhametov
Quantitative Nanofriction Characterization of Corrugated Surfaces by Atomic Force Microscopy
Atomic Force Microscopy (AFM) is a suitable tool to perform tribological
characterization of materials down to the nanometer scale. An important aspect
in nanofriction measurements of corrugated samples is the local tilt of the
surface, which affects the lateral force maps acquired with the AFM. This is
one of the most important problems of state-of-the-art nanotribology, making
difficult a reliable and quantitative characterization of real corrugated
surfaces. A correction of topographic spurious contributions to lateral force
maps is thus needed for corrugated samples. In this paper we present a general
approach to the topographic correction of AFM lateral force maps and we apply
it in the case of multi-asperity adhesive contact. We describe a complete
protocol for the quantitative characterization of the frictional properties of
corrugated systems in the presence of surface adhesion using the AFM.Comment: 33 pages, 9 figures, RevTex 4, submitted to Journal of Applied
Physic
Melting Point and Lattice Parameter Shifts in Supported Metal Nanoclusters
The dependencies of the melting point and the lattice parameter of supported
metal nanoclusters as functions of clusters height are theoretically
investigated in the framework of the uniform approach. The vacancy mechanism
describing the melting point and the lattice parameter shifts in nanoclusters
with decrease of their size is proposed. It is shown that under the high vacuum
conditions (p<10^-7 torr) the essential role in clusters melting point and
lattice parameter shifts is played by the van der Waals forces of
cluster-substrate interation. The proposed model satisfactorily accounts for
the experimental data.Comment: 6 pages, 3 figures, 1 tabl
Crystal Undulator As A Novel Compact Source Of Radiation
A crystalline undulator (CU) with periodically deformed crystallographic
planes is capable of deflecting charged particles with the same strength as an
equivalent magnetic field of 1000 T and could provide quite a short period L in
the sub-millimeter range. We present an idea for creation of a CU and report
its first realization. One face of a silicon crystal was given periodic
micro-scratches (grooves), with a period of 1 mm, by means of a diamond blade.
The X-ray tests of the crystal deformation have shown that a sinusoidal-like
shape of crystalline planes goes through the bulk of the crystal. This opens up
the possibility for experiments with high-energy particles channeled in CU, a
novel compact source of radiation. The first experiment on photon emission in
CU has been started at LNF with 800 MeV positrons aiming to produce 50 keV
undulator photons.Comment: Presented at PAC 2003 (Portland, May 12-16
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