oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 257 )

2018 ( 310 )

2017 ( 294 )

2016 ( 439 )

Custom range...

Search Results: 1 - 10 of 200880 matches for " I. V. Grigorieva "
All listed articles are free for downloading (OA Articles)
Page 1 /200880
Display every page Item
Van der Waals heterostructures
A. K. Geim,I. V. Grigorieva
Physics , 2013, DOI: 10.1038/nature12385
Abstract: Research on graphene and other two-dimensional atomic crystals is intense and likely to remain one of the hottest topics in condensed matter physics and materials science for many years. Looking beyond this field, isolated atomic planes can also be reassembled into designer heterostructures made layer by layer in a precisely chosen sequence. The first - already remarkably complex - such heterostructures (referred to as 'van der Waals') have recently been fabricated and investigated revealing unusual properties and new phenomena. Here we review this emerging research area and attempt to identify future directions. With steady improvement in fabrication techniques, van der Waals heterostructures promise a new gold rush, rather than a graphene aftershock.
Optimal control of pollution stock through ecological interaction of the manufacturer and the state
Grigorieva,Ellina V; Khailov,Evgenii N; Kharitonova,E.I;
Revista de Matemática Teoría y Aplicaciones , 2011,
Abstract: a model of an interaction between a manufacturer and the state where the manufacturer produces a single product and the state controls the level of pollution is created and investigated. a local economy with a stock pollution problem that must choose between productive and environmental investments (control functions) is considered. the model is described by a nonlinear system of two differential equations with two bounded controls. the best optimal strategy is found analytically with the use of the pontryagin maximum principle and green’s theorem.
Optimal control of pollution stock through ecological interaction of the manufacturer and the state Control óptimo de contaminación almacenada a través de interacción ecológica entre el fabricante y el estado
Ellina V Grigorieva,Evgenii N Khailov,E.I Kharitonova
Revista de Matemática Teoría y Aplicaciones , 2011,
Abstract: A model of an interaction between a manufacturer and the state where the manufacturer produces a single product and the state controls the level of pollution is created and investigated. A local economy with a stock pollution problem that must choose between productive and environmental investments (control functions) is considered. The model is described by a nonlinear system of two differential equations with two bounded controls. The best optimal strategy is found analytically with the use of the Pontryagin Maximum Principle and Green’s Theorem. Se ha creado e investigado un modelo de interaccin entre un fabricante y el estado donde el fabricante produce un solo producto y el estado controla el nivel de contaminación. Se considera una economía local con un problema de contaminación almacenada, que debe escoger entre inversiones en producción y medio ambiente (funciones de control). El modelo es descrito por un sistema de dos ecuaciones diferenciales con dos controles acotados. La mejor estrategia de control se encuentra analíticamente usando el Principio del Máximo de Pontryagin y el Teorema de Green.
On astrophysical solution to ultra high energy cosmic rays
V. Berezinsky,A. Z. Gazizov,S. I. Grigorieva
Physics , 2002, DOI: 10.1103/PhysRevD.74.043005
Abstract: We argue that an astrophysical solution to UHECR problem is viable. The pectral features of extragalactic protons interacting with CMB are calculated in model-independent way. Using the power-law generation spectrum $\propto E^{-\gamma_g}$ as the only assumption, we analyze four features of the proton spectrum: the GZK cutoff, dip, bump and the second dip. We found the dip, induced by electron-positron production on CMB, as the most robust feature, existing in energy range $1\times 10^{18} - 4\times 10^{19}$ eV. Its shape is stable relative to various phenomena included in calculations. The dip is well confirmed by observations of AGASA, HiRes, Fly's Eye and Yakutsk detectors. The best fit is reached at $\gamma_g =2.7$, with the allowed range 2.55 - 2.75. The dip is used for energy calibration of the detectors. After the energy calibration the fluxes and spectra of all three detectors agree perfectly, with discrepancy between AGASA and HiRes at $E> 1\times 10^{20}$ eV being not statistically significant. The agreement of the dip with observations should be considered as confirmation of UHE proton interaction with CMB. The dip has two flattenings. The high energy flattening at $E \approx 1\times 10^{19}$ eV automatically explains ankle. The low-energy flattening at $E \approx 1\times 10^{18}$ eV provides the transition to galactic cosmic rays. This transition is studied quantitatively. The UHECR sources, AGN and GRBs, are studied in a model-dependent way, and acceleration is discussed. Based on the agreement of the dip with existing data, we make the robust prediction for the spectrum at $1\times 10^{18} - 1\times 10^{20}$ eV to be measured in the nearest future by Auger detector.
Ultra high energy cosmic rays from extragalactic astrophysical sources: energy losses and spectra
V. Berezinsky,A. Z. Gazizov,S. I. Grigorieva
Physics , 2001,
Abstract: The energy losses and spectra of Ultra High Energy Cosmic Rays (UHECR) are calculated for protons as primary particles. The attention is given to the energy losses due to electron-positron production in collisions with the microwave 2.73 K photons. The energy spectra are calculated for several models, which differ by production spectra and by source distribution, namely: (i) Uniform distribution of the sources with steep generation spectra with indices 2.4 - 2.7, with cosmological evolution and without it. In this case it is possible to fit the shape of the observed spectrum up to 8.10^{19} eV, but the required CR emissivity is too high and the GZK cutoff is present. (ii) Uniform distribution of the sources with flat generation spectrum dE/E^2 which is relevant to GRBs. The calculated spectrum is in disagreement with the observed one. The agreement at E\lesssim 8.10^{19} eV can be reached using a complex generation spectrum, but the required CR emissivity is three orders of magnitude higher than that of GRBs, and the predicted spectrum has the GZK cutoff. (iii) The case of local enhancement within region of size 10 - 30 Mpc with overdensity given by factor 3- 30. The overdensity larger than 10 is needed to eliminate the GZK cutoff.
Signatures of AGN model for UHECR
V. Berezinsky,A. Z. Gazizov,S. I. Grigorieva
Physics , 2002,
Abstract: We demonstrate that the energy spectra of Ultra High Energy Cosmic rays (UHECR) as observed by AGASA, Fly's Eye, HiRes and Yakutsk detectors, have the imprints of UHE proton interaction with the CMB radiation in the form of the dip at $E\sim 1\times 10^{19}$~ eV, of the beginning of the GZK cutoff, and of very good agreement with calculated spectrum shape. We argue that these data, combined with small-angle clustering and correlation with AGN (BL Lacs), point to the AGN model of UHECR origin at energies $E \lsim 1\times 10^{20}$ eV. The excess of the events at $E \gsim 1\times 10^{20}$ eV, which is observed by AGASA (but absent in HiRes data) can be explained by another component of UHECR, e.g. by UHECR from superheavy dark matter.
Reply to Comment by D. Spemann et al [EPL 98 (2012) 57006, arXiv:1204.2992]
M. Sepioni,R. R. Nair,I. -Ling Tsai,A. K. Geim,I. V. Grigorieva
Physics , 2012, DOI: 10.1209/0295-5075/98/57007
Abstract: This article is a reply to the Comment by D. Spemann et al (arXiv:1204.2992) in response to our paper 'Revealing common artifacts due to ferromagnetic inclusions in highly oriented pyrolytic graphite' (EPL, 97 (2012) 47001).
Revealing common artifacts due to ferromagnetic inclusions in highly-oriented pyrolytic graphite
M. Sepioni,R. R. Nair,I-Ling Tsai,A. K. Geim,I. V. Grigorieva
Physics , 2012, DOI: 10.1209/0295-5075/97/47001
Abstract: We report on an extensive investigation to figure out the origin of room-temperature ferromagnetism that is commonly observed by SQUID magnetometry in highly-oriented pyrolytic graphite (HOPG). Electron backscattering and X-ray microanalysis revealed the presence of micron-size magnetic clusters (predominantly Fe) that are rare and would be difficult to detect without careful search in a scanning electron microscope in the backscattering mode. The clusters pin to crystal boundaries and their quantities match the amplitude of typical ferromagnetic signals. No ferromagnetic response is detected in samples where we could not find such magnetic inclusions. Our experiments show that the frequently reported ferromagnetism in pristine HOPG is most likely to originate from contamination with Fe-rich inclusions introduced presumably during crystal growth.
Ionospheric effects during first 2 hours after the Chelyabinsk meteorite impact
O. I. Berngardt,V. I. Kurkin,G. A. Zherebtsov,O. A. Kusonski,S. A. Grigorieva
Physics , 2013,
Abstract: This paper presents the analysis of ionospheric effects in the region close to the Chelyabinsk meteorite explosion at 03:20UT 2013 February 15 from the Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences (ISTP SB RAS) EKB radar data, and from the Institute of Geophysics of Ural Branch of Russian Academy of Sciences (IG UB RAS) PARUS ionosonde data. Both instruments are located within the IG UB RAS Arti Observatory approximately 200 km northward from the estimated explosion site. According to the data obtained, the ionospheric disturbance caused by the meteorite flyby, explosion, and impact had high dynamics and amplitude. However, it obviously did not lead to a variation in the ionosphere mean parameters in the region above the disturbance center during the first 2 hours. Essential effects, however, were observed at more than 100-200 km from the explosion site and farther up to 1500 km.
Chemical Tuning of Adsorption Properties of Titanate Nanotubes
Anastasia V. Grigorieva,Valentina V. Yuschenko,Irina I. Ivanova,Eugene A. Goodilin
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/920483
Abstract:
Page 1 /200880
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.