992 research outputs found

    Regional population expenditure for foodstuffs in the Russian Federation: componential and cluster analyses

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    The article describes the solving of the problem of conducting the component and cluster analyses of population expenditure on food as one of the most important components of the standard of living. The purpose of the analysis is to develop the regional clusters of the Russian Federation, which vary in the structure of household expenditure for foodstuffs. The foodstuffs are presented in absolute units taking into integral account the standard of living index. The methods of intellectual analysis such as component and cluster analyses are applied as the research methods. The procedure for the data intellectual analysis based on the interconnected performance of component and cluster analyses is proposed. The procedure of the data intellectual analysis considers the interrelation between the results received by different methods, and also the possibility to return to the previous method for the purpose of repeating the analysis to specify consistently the clusters composition. Few clusters of the wealthy regions characterized by the high and average levels of expenditure for foodstuffs are revealed as well as the quite many clusters of not enough wealthy and not wealthy regions characterized by the low level of expenditure for foodstuffs. It is shown that the growth of standard of living characterized by the size of a gross regional product per capita is followed by the growth of the Gini coefficient, which indicates both the inequality of income distribution and reduction in expenditure for low-value foodstuffs. The results of the analysis can be applied to the development of the decision-making support system intended for the analysis of the scenarios of macroeconomic regulation in the eld of income policy for the purpose of increasing the standard of living of population. The analysis of the population expenditure for foodstuffs has allowed to reveal the cluster structure of the regions of the Russian Federation, to show it according to the generalized indications, to formulate the specific characteristics of the clusters of the regions and important management decisions

    Spin-transfer mechanism of ferromagnetism in polymerized fullerenes: AbinitioAb initio calculations

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    A mechanism of the high temperature ferromagnetism in polymerized fullerenes is suggested. It is assumed that some of the C60_{60} molecules in the crystal become magnetically active due to spin and charge transfer from the paramagnetic impurities (atoms or groups), such as hydrogen, fluorine, hydroxyl group OH, amino group NH2_2, or methyl group CH3_3, dispersed in the fullerene matrix. The exchange interaction between the spins localized on the magnetically active fullerenes is evaluated using \textit{ab initio} calculations. The nearest neighbour and next nearest neighbour exchange interaction is found to be in the range 0.1÷0.30.1\div 0.3 eV, that is, high enough to account for the room temperature ferromagnetism.Comment: typos corrected, 8 pages, 3 figures, LaTe

    Kramers-Kronig constrained variational analysis of optical spectra

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    A universal method of extraction of the complex dielectric function ϵ(ω)=ϵ1(ω)+iϵ2(ω)\epsilon(\omega)=\epsilon_{1}(\omega)+i\epsilon_{2}(\omega) from experimentally accessible optical quantities is developed. The central idea is that ϵ2(ω)\epsilon_{2}(\omega) is parameterized independently at each node of a properly chosen anchor frequency mesh, while ϵ1(ω)\epsilon_{1}(\omega) is dynamically coupled to ϵ2(ω)\epsilon_{2}(\omega) by the Kramers-Kronig (KK) transformation. This approach can be regarded as a limiting case of the multi-oscillator fitting of spectra, when the number of oscillators is of the order of the number of experimental points. In the case of the normal-incidence reflectivity from a semi-infinite isotropic sample the new method gives essentially the same result as the conventional KK transformation of reflectivity. In contrast to the conventional approaches, the proposed technique is applicable, without readaptation, to virtually all types of linear-response optical measurements, or arbitrary combinations of measurements, such as reflectivity, transmission, ellipsometry {\it etc.}, done on different types of samples, including thin films and anisotropic crystals.Comment: 10 pages, 7 figure

    Determination of the sustainability of the project portfolio of the oil and gas sector of the economy to external factors

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    The oil and gas sector of the economy in many states remains the main source of foreign exchange and tax revenues to the budget. Moreover, its share, for example, in Russia, accounts for about 12 % of all industrial production. However, this sector, as the practice of world oil prices shows, is experiencing not only a rise, but also a decline. Consequently, the problem of forming a balanced portfolio of oil and gas assets is an object of close attention on the part of national oil and gas companies. The issues of choosing the optimal combination of oil and gas assets in the portfolio are no less urgent, especially among the tasks that all oil and gas companies face, both in Russia and abroad. An investment portfolio or a portfolio of oil and gas assets, which includes new projects for the commissioning of fields, as well as measures to enhance oil recovery, and exploration are objects of real investment. The high volatility of the oil and gas industry is influenced by various factors, including: macroeconomic, innovation risks and a number of others. These circumstances stimulate the sector to increase the resilience of its project portfolios in order to respond flexibly to changes. In an increasingly challenging and uncertain environment, oil and gas companies around the world face constant pressures as difficult strategic decisions and building long-term plans lead to a sustainable portfolio. In order to achieve their goals and maximize profitability, companies should apply certain algorithms in their practice. The article substantiates the role and importance of project portfolio management in achieving the goals of the state and companies in the oil and gas sector. The main goal of the article is to build an algorithm that is aimed both at determining the stability of the portfolio and the ability to flexibly respond to changes in the environment. The scientific novelty of the research lies in the determination of an algorithm for assessing the sustainability of a portfolio of projects of oil and gas companies. Application of this algorithm will allow oil and gas companies to take into account the influence of external factors. The research methodology is based on such methods as analysis of internal regulations and reporting of companies for project portfolio management, risk analysis, project ranking; grouping and classification method

    The Evolutionary Status of Isolated Dwarf Irregular Galaxies II. Star Formation Histories and Gas Depletion

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    The results of UBV and H alpha imaging of a large sample of isolated dwarf irregular galaxies are interpreted in the context of composite stellar population models. The observed optical colors are best fit by composite stellar populations which have had approximately constant star formation rates for at least 10 Gyr. The galaxies span a range of central surface brightness, from 20.5 to 25.0 mag arcsec^{-2}; there is no correlation between surface brightness and star formation history. Although the current star formation rates are low, it is possible to reproduce the observed luminosities without a major starburst episode. The derived gas depletion timescales are long, typically ~20 Gyr. These results indicate that dwarf irregular galaxies will be able to continue with their slow, but constant, star formation activity for at least another Hubble time. The sample of isolated dIs is compared to a sample of star bursting dwarf galaxies taken from the literature. The star bursting dwarf galaxies have many similar properties; the main difference between these two types of gas-rich dwarf galaxies is that the current star formation is concentrated in the center of the star bursting systems while it is much more distributed in the quiescent dIs. This results in pronounced color gradients for the starbursting dwarf galaxies, while the majority of the quiescent dwarf irregular galaxies have minor or non-existent color gradients. Thus, the combination of low current star formation rates, blue colors, and the lack of significant color gradients indicates that star formation percolates slowly across the disk of normal dwarf galaxies in a quasi-continuous manner.Comment: 16 pages, uses emulateapj, to appear in The Astronomical Journal (April 2001

    An imaging and spectroscopic study of the very metal-deficient blue compact dwarf galaxy Tol 1214--277

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    We present a spectrophotometric study based on VLT/FORS I observations of one of the most metal-deficient blue compact dwarf (BCD) galaxies known, Tol 1214-277 (Z ~ Zsun/25). The data show that roughly half of the total luminosity of the BCD originates from a bright and compact starburst region located at the northeastern tip of a faint dwarf galaxy with cometary appearance. The starburst has ignited less than 4 Myr ago and its emission is powered by several thousands O7V stars and ~ 170 late-type nitrogen Wolf-Rayet stars located within a compact region with < 500 pc in diameter. For the first time in a BCD, a relatively strong [Fe V] 4227 emission line is seen which together with intense He II 4686 emission indicates the presence of a very hard radiation field in Tol 1214-277. We argue that this extraordinarily hard radiation originates from both Wolf--Rayet stars and radiative shocks in the starburst region. The structural properties of the low-surface-brightness (LSB) component underlying the starburst have been investigated by means of surface photometry down to 28 B mag/sq.arcsec. We find that, for a surface brightness level fainter than ~ 24.5 B mag/sq.arcsec, an exponential fitting law provides an adequate approximation to its radial intensity distribution. The broad-band colors in the outskirts of the LSB component of Tol 1214-277 are nearly constant and are consistent with an age below one Gyr. This conclusion is supported by the comparison of the observed spectral energy distribution (SED) of the LSB host with theoretical SEDs.Comment: 17 pages, 11 Postscript figures, uses emulateapj.sty, to appear in Astronomical Journa

    High-temperature ferromagnetism of spsp electrons in narrow impurity bands: Application to CaB6_6

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    Ferromagnetism with high Curie temperature TcT_c, well above room temperature, and very small saturation moment has been reported in various carbon and boron systems. It is argued that the magnetization must be very inhomogeneous with only a small fraction of the sample ferromagnetically ordered. It is shown that a possible source of high TcT_c within the ferromagnetic regions is itinerant electrons occupying a narrow impurity band. Correlation effects do not reduce the effective interaction which enters the Stoner criterion in the same way as in a bulk band. It is also shown how, in the impurity band case, spin wave excitations may not be effective in lowering TcT_c below its value given by Stoner theory. These ideas are applied to CaB6_6 and a thorough review of the experimental situation in this material is given. It is suggested that the intrinsic magnetism of the B2_2 and O2_2 dimers might be exploited in suitable structures containing these elements.Comment: 26 pages, 2 figure

    Effect of Distributed Photovoltaic Generation on the Voltage Magnitude in a Self-Contained Power Supply System

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    A promising way to increase the technical and economic characteristics of standalone power supply systems is to incorporate renewable energy installations in their structure. This saves fuel and extends the operational life of diesel power stations. The most common option is a hybrid system with photovoltaic power stations incorporated into the local network of the diesel power station. This paper deals with the dependence of the deflection voltage and power losses in the electric power transmission line on the graphs of electrical loads, the parameters of elements of the power supply system, connection points and the capacity of distributed photovoltaic power stations. Research has been carried out on the common low-voltage power supply systems of the radial type (0.4 kV) with an installed capacity of up to 100 kW. The studies have been conducted by simulating the operating modes of hybrid power systems of various configurations. As a result of these studies recommendations to reduce losses and voltage variations in the network by selecting the power and photovoltaic power connection points have been put forward
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