126 research outputs found

    Credibility of economic reform and foreign direct investment in the former Soviet Union region

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    Economic transition from socialist to market-based economy has been the subject of intense economic research in the last two decades. However, there are very few publications that address the transitional issues from the traditional microeconomics theory prospective. This dissertation focuses on several transitional issues. The first topic is: what is the economic nature and major characteristics of economic reform? Secondly, the dissertation focuses on the relationship between the government and private sector in the reform environment. In the end, the focus of the dissertation shifts to the question of economic reform credibility and of finding the most efficient ways to support the economic reform objectives;To find the answers to the above questions this dissertation develops two models of economic reform: a pre-commitment model and a time consistent model to show that besides the traditional reasons that effect the speed and intensity of economic reform, the sequence and timing of decisions is critical to the outcomes of the reform. We show that because private agents correctly anticipate that the government has the ability to change its previously announced policy, private sector support of the government\u27s reform efforts may be much weaker relative to what it could be if the pre-commitment mechanism existed. We also show that the absence of the pre-commitment mechanism not only effect the speed and intensity of economic reform in the future but also may effect the level of reform activity in the initial stages of economic reform. For example, we show that if there is no pre-commitment mechanism it is possible that the government could be interested in increasing the level of reform efforts during the initial stages of reform. This can increase the probability of political reversal which is of a great concern of all private investors;We show that a pre-commitment solution is more desirable comparing to the time consistent solution and that a pre-commitment mechanism is required to enhance the credibility of the pre-commitment solution. And we propose such a mechanism that together with other pre-commitment mechanism can be applied in transition economies, especially in the initial stages of the reform

    Onset of chaotic dynamics in a ball mill: attractors merging and crisis induced intermittency

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    In mechanical treatment carried out by ball milling, powder particles are subjected to repeated high-energy mechanical loads which induce heavy plastic deformations together with fracturing and cold-welding events. Owing to the continuous defect accumulation and interface renewal, both structural and chemical transformations occur. The nature and the rate of such transformations have been shown to depend on variables, such as impact velocity and collision frequency that depend, in turn, on the whole dynamics of the system. The characterization of the ball dynamics under different impact conditions is then to be considered a necessary step in order to gain a satisfactory control of the experimental set up. In this paper we investigate the motion of a ball in a milling device. Since the ball motion is governed by impulsive forces acting during each collision, no analytical expression for the complete ball trajectory can be obtained. In addition, mechanical systems exhibiting impacts are strongly nonlinear due to sudden changes of velocities at the instant of impact. Many different types of periodic and chaotic impact motions exist indeed even for simple systems with external periodic excitation forces. We present results of the analysis on the ball trajectory, obtained from a suitable numerical model, under growing degree of impact elasticity. A route to high dimensional chaos is obtained. Crisis and attractors merging are also found

    Unconventional magnetism of non-uniform distribution of Co in TiO2 nanoparticles

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    High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) analysis, electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), magnetic methods, and density-functional theory (DFT) calculations were applied for the investigations of Co-doped anatase TiO2 nanoparticles (∼20 nm). It was found that high-spin Co2+ ions prefer to occupy the interstitial positions in the TiO2 lattice which are the most energetically favourable in compare to the substitutional those. A quantum mechanical model which operates mainly on two types of Co2+ – Co2+ dimers with different negative exchange interactions and the non-interacting paramagnetic Co2+ ions provides a satisfactorily description of magnetic properties for the TiO2:Co system. © 2020 Elsevier B.V.Russian Foundation for Basic Research. Ministry of Science and Higher Education of the Russian Federatio

    Magnetic properties and structure of TiO2-Mn (0.73 %) nanopowders: The effects of electron irradiation and vacuum annealing

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    Nanopowder TiO2-0.73 % Mn was synthesized by the sol-gel method. Thermal treatment of the samples was carried out in vacuum at a temperature of 500°C. Magnetic properties were studied in the temperature range from 2 to 850 K. The effects of electron irradiation and vacuum annealing on the EPR spectra and magnetic properties of TiO2-Mn powder are discussed. It was established that a part of manganese ions in the anatase crystal lattice interacts antiferromagnetically, which causes a decrease in magnetization as compared to the result of the calculation for non-interacting ions. Vacuum annealing leads to the formation of oxygen vacancies and, at the same time, to a noticeable increase in the ferromagnetic contribution to magnetization, especially, after preliminary electron irradiation. We assume that the ferromagnetic contribution to the magnetization appears either due to incomplete compensation of antiferromagnetically directed moments of manganese ions, or due to positive exchange interactions of Mn ions via defects in the TiO2 lattice. It is shown that the temperature of magnetic disordering in samples with a spontaneous magnetic moment exceeds 600°C. © 2019, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved

    Carbon States in Carbon-Encapsulated Nickel Nanoparticles Studied by Means of X-Ray Absorption, Emission, and Photoelectron Spectroscopies

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    Electronic structure of nickel nanoparticles encapsulated in carbon was characterized by photoelectron, X-ray absorption, and X-ray emission spectroscopies. Experimental spectra are compared with the density of states calculated in the frame of the density functional theory. The carbon shell of Ni nanoparticles has been found to be multilayer graphene with significant (about 6%) amount of Stone--Wales defects. Results of the experiments evidence protection of the metallic nanoparticles from the environmental degradation by providing a barrier against oxidation at least for two years. Exposure in air for 2 years leads to oxidation only of the carbon shell of Ni@C nanoparticles with coverage of functional groups.Comment: 16 pages, 6 figures, accepted in J. Phys. Chem.
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