4,762 research outputs found
Isochoric thermal conductivity of solid nitrogen
The isochoric thermal conductivity of solid nitrogen has been investigated on
four samples of different densities in the temperature interval from 20 K to
the onset of melting. In alfa-N2 the isochoric thermal conductivity exhibits a
dependence weaker than 1/T; in beta-N2 it increases slightly with temperature.
The experimental results are discussed within a model in which the heat is
transported by low-frequency phonons or by "diffusive" modes above the mobility
boundary. The growth of the thermal conductivity in beta-N2 is attributed to
the decreasing "rotational" component of the total thermal resistance, which
occurs as the rotational correlations between the neighboring molecules become
weaker.Comment: Postscript 12 pages, 3 figures, 1 table. To be published in 200
Simulation of the software-defined network for a high-performance computing cluster
The study considers the issues of using the software-defined networks, the current state of the research trends in this area and the most significant projects. The simulation of a high-performance computer network for increase in the performance of the university computing cluster due to the optimization of topology and network traffic between the computational nodes is describe
On Possible Measurement of Gravitational Interaction Parameters on Board a Satellite
The recently suggested SEE (Satellite Energy Exchange) method of measuring
the gravitational constant , possible equivalence principle violation
(measured by the E\"{o}tv\"{o}s parameter ) and the hypothetic 5th force
parameters and on board a drag-free Earth's satellite is
discussed and further developed. Various particle trajectories near a heavy
ball are numerically simulated. Some basic sources of error are analysed. The
measurement procedure is modelled by noise insertion to a ``true''
trajectory. It is concluded that the present knowledge of (for
m) and can be improved by at least two orders of
magnitude.Comment: (only two misprints on title page) 7 page
Analogue of the Kubo Formula for Conductivity of Spatially Inhomogeneous Systems and Electric Fields
The average of densities of currents and charges, induced by a weak
electromagnetic field in spatially inhomogeneous are calculated at final
temperatures. The Kubo formula for a conductivity tensor is generalized for
spatially inhomogeneous systems and fields. The contributions containing
electric fields and derivative from fields on coordinates are allocated. The
Semiconductor quantum wells, wires and dots may be considered as spatially
inhomogeneous systems.Comment: 10 page
Measurement of the status of complex systems in multidimensional phase spaces
A method for complex measurement of the state of objects in relation to the reference state and the reference process has been developed, based on obtaining state equations in the form of phenomenological relationships and using multidimensional scaling methods. As examples, the equations of states are obtained and measuring scales for two complex systems are constructed. The first example is related to the study of the similarity of biological species in the three-dimensional phase space of state variables. The second example uses statistical data on the state and development of Russian citie
Tunneling-assisted impact ionization fronts in semiconductors
We propose a novel type of ionization front in layered semiconductor
structures. The propagation is due to the interplay of band-to-band tunneling
and impact ionization. Our numerical simulations show that the front can be
triggered when an extremely sharp voltage ramp () is
applied in reverse direction to a Si structure that is connected in
series with an external load. The triggering occurs after a delay of 0.7 to 0.8
ns. The maximal electrical field at the front edge exceeds .
The front velocity is 40 times faster than the saturated drift velocity
. The front passes through the base with a thickness of
within approximately 30 ps, filling it with dense electron-hole plasma. This
passage is accompanied by a voltage drop from 8 kV to dozens of volts. In this
way a voltage pulse with a ramp up to can be applied to the
load. The possibility to form a kilovolt pulse with such a voltage rise rate
sets new frontiers in pulse power electronics.Comment: 12 pages, 6 figure
On Quantitative Information Measures For State Spaces of Complex Systems
An approach to the study of the information phenomenon is proposed on the basis of the use of information measures in creating models for describing temporal data characterizing complex systems. A theoretical and experimental substantiation for the validity of the conservation law for an information quantity measure has been carried out on the basis of using the existing natural-science concepts on the continuity of the state spaces of systems. System-wide provisions related to the principles of the existence of entropy and potential in state spaces were formulated. As an example, the possibilities of using the proposed method in the description of experimental data characterizing the physical and biological systems are presented
Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector
The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV
for the direct photon emission in the K- --> pi- pi0 gamma decay has been
measured using in-flight decays detected with the ISTRA+ setup operating in the
25 GeV/c negative secondary beam of the U-70 PS. The value
Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930
completely reconstructed events is consistent with the average value of two
stopped-kaon experiments, but it differs by 2.5 standard deviations from the
average value of three in-flight-kaon experiments. The result is also compared
with recent theoretical predictions.Comment: 13 pages, 8 figure
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