236 research outputs found
Random Time-Scale Invariant Diffusion and Transport Coefficients
Single particle tracking of mRNA molecules and lipid granules in living cells
shows that the time averaged mean squared displacement of
individual particles remains a random variable while indicating that the
particle motion is subdiffusive. We investigate this type of ergodicity
breaking within the continuous time random walk model and show that
differs from the corresponding ensemble average. In
particular we derive the distribution for the fluctuations of the random
variable . Similarly we quantify the response to a
constant external field, revealing a generalization of the Einstein relation.
Consequences for the interpretation of single molecule tracking data are
discussed.Comment: 4 pages, 4 figures.Article accompanied by a PRL Viewpoint in
Physics1, 8 (2008
Beam-size effect and particle losses at Super factory (Italy)
In the colliders, the macroscopically large impact parameters give a
substantial contribution to the standard cross section of the process. These impact parameters may be much larger than the
transverse sizes of the colliding bunches. It means that the standard cross
section of this process has to be substantially modified. In the present paper
such a beam-size effect is calculated for bremsstrahlung at Super factory
developed in Italy. We find out that this effect reduces beam losses due to
bremsstrahlung by about 40%.Comment: 11 pages, 4 figure
The Separable Kernel of Nucleon-Nucleon Interaction in the Bethe-Salpeter Approach
The dispersion relations for nucleon-nucleon (NN) T-matrix in the framework
of Bethe-Salpeter equation for two spin one-half particle system and with
separable kernel of interaction are considered in the paper. The developed
expressions are applied for construction of the separable kernel of interaction
for S partial-waves in singlet and triplet channels. We calculate the low
energy scattering parameters and the phase shifts and also the deuteron binding
energy with the separable interaction. The approach can be easily extended to
higher partial-waves for NN-scattering and other reactions (anti N N-, pi
N-scattering).Comment: RevTex 4 style, 9 pages, 1 figur
The effect of thickness on the properties of laser-deposited NiBSi-WC coating on a Cu-Cr-Zr substrate
Ni/60WC coatings on copper substrate were placed via laser deposition (LD). A structural study was conducted using electron microscopy and a microhardness evaluation. Two body abrasive wear tests were conducted with a pin-on-plate reciprocating technique. A tool steel X12MF GOST 5960 (C-Cr-Mo-V 1.6-12-0.5-0.2) with a hardness of 63 HRC was used as a counterpart. The following results were obtained: Precipitation of the secondary carbides takes place in the thicker layers. Their hardness is lower than that of the primary carbides in the deposition (2425 HV vs. 2757 HV) because they mix with the matrix material. In the thin layers, precipitation is restricted due to a higher cooling rate. For both LD coatings, the carbide's hardness increases compared to the initial mono-tungsten carbide (WC)-containing powder (2756 HV vs. 2200 HV). Such a high level of microhardness reflects the combined influence of a low level of thermal destruction of carbides during laser deposition and the formation of a boride-strengthening phase from the matrix powder. The thicker layer showed a higher wear resistance; weight loss was 20% lower. The changes in the thickness of the laser deposited Ni-WC coating altered its structure and wear resistance. © 2019 by the authors.Acknowledgments: This work was supported by the state orders of IMP UB RAS on the subjects “Laser”, “Structure”. The authors are grateful to the collective use center “Plastometry” of the Institute of Mechanical Engineering of the Ural Branch of the Russian Academy of Sciences for their help in conducting structural studies
Nanostructuring and surface hardening of structural steels by ultrasonic impact-frictional treatment
With two structural steels (the steels 50 and 09G2S) as examples, the paper studies the effectiveness of a new method of ultrasonic impact-frictional treatment (UIFT) for the hardening and nanostructuring of the surface layer with the variation of the tilt angle of the vibrating indenter and the treatment environment. It is demonstrated that treatment with tool tilt angles different from 90° and with the absence of a contact liquid results in the formation of a nanostructured surface layer with increased microhardness. © 2018 Author(s)
Structure study of laser treated NiBSi/WC coatings on bronze substrate
Metal matrix composite layers like NiCrB-WC on the substrate of bronze C18150 were performed by laser deposition. The influence of layer thickness and operating parameters on the structural characteristics, microhardness, and crack susceptibility were analyzed. Rational technological modes were defined applied to a diode laser.Проведено сравнение металоматричных покрытий вида NiCrB-WC на основе из бронзы С18150, полученных лазерной наплавкой на основе из бронзы CuCrZr. Проанализированы зависимости изменений структурных характеристик, твердости, склонности к образованию трещин от толщины покрытий и технологических параметров. Определены рациональные режимы обработки с использованием диодного лазера
One-rank interaction kernel of the two-nucleon system for medium and high energies
A new version of the separable kernel of the nucleon-nucleon interaction in
the Bethe-Salpeter approach is presented. The phase shifts are fitted to recent
experimental data for singlet and uncoupled triplet partial waves of the
neutron-proton scattering with total angular momenta J=0,1. The results are
compared with other model calculations.Comment: 10 pages, 5 figures, 3 table
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