166 research outputs found
Influence of overload on low-frequency instability of working process in the combustion chamber of the solid propellant rocket engine
In the paper the real oscillatory process is reproduced by statement of direct numerical experiment and the mechanism of occurrence and refill of low-frequency acoustic instability in the combustion chamber of the solid propellant rocket engine with the account of flight overload is investigated for the first time. The direct numerical modeling of low-frequency acoustic instability is carried out by means of Davydov’s method (method of large particles), which is well-suited for the solutions of many problems of mechanics of the continuous media. The results of numerical modeling are presented here. The hydrodynamic highly nonlinear nature of low-frequency fluctuations connected to structure and character of current in the combustion chamber of the rocket engine on firm fuel are proved to be tru
New types of stable nonlinear whistler waveguides
International audienceThe stationary self-focusing of whistler waves with frequencies near half of the electron-cyclotron frequency in the ionospheric plasma is considered in the framework of a two-dimensional generalized nonlinear Schrödinger equation including fourth-order dispersion effects and nonlinearity saturation. New types of soliton-like (with zero topological charge) and vortex-like nonlinear waveguides are found, and their stability confirmed both analytically and numerically
Fast recognition of marine particles in underwater digital holography
The issue of fast recognition of marine particles in situ by digital holography methods is considered. An algorithm for the classification of marine particles by morphological features is proposed. Preliminary results and estimation of accuracy of the proposed algorithm are presented
Mathematical model for analyzing the interrelation between monetary circulation and economic growth in developing countries
Objective to develop a basic mathematical model to assess the impact of foreign trade on the national economy and the impact of the national currency on economic growth in relation to developing countries.
Methods methods of mathematical dynamic modeling are used in the development of the model.
Results one of the most acute and unresolved problems for the Russian economy is the development of such currencymonetary policy that would provide opportunities for economic growth. One of the reasons for the ongoing disputes is the lack of a qualitative mathematical model that allows assessing its impact on economic processes. Mathematical models proposed by representatives of different economic scientifc schools and describing the impact of monetization on the economy are considered. It is determined that the previously developed models are not applicable to the economies of developing countries. The characteristic is given of the dynamic mathematical model earlier developed by the authors describing cash flows in the Russian economy. The importance of models for developing economies is analyzed in terms of growth of the money supply and changes in the exchange rate of the national currency. As a result it is determined that the constructed model which is an aggregate version of the model of switching reproduction takes into account the openness of the national economy and inflation processes. The model is tested on the example of currencymonetary policy of the USA and Russia.
Scientific novelty the model differs from analogues in that it is based on the modeling of cash flows in accordance with the methodology of modeling of switching reproduction which allows analyzing the interaction of fnancial and real sectors of economy in developing countries.
Practical significance the model allows estimating the consequences of decisions in the feld of currencymonetary policy in developing countries
Digital holographic camera for plankton monitoring
A submersible digital holographic camera for measuring plankton and other particles is described. The camera provides underwater recording of digital holograms of water volume containing plankton followed by automatic restoration of holographic images of plankton species, determination of their sizes, shapes, and concentrations, and their recognition and classification. Particles with sizes of 200 μm and larger are analyzed. The water volume registered per exposure is about 1 L. The special features of the software for automatic information retrieval from digital holograms are discussed. Examples of application of the camera as an integral part of the hardware-software complex for field measurements are given. Prospects for application of this complex for ecological monitoring are discussed. The recognition criterion of the digital holographic camera and the data volume and the averaging time required for obtaining statistically reliable data on plankton species are also given
Stable multiple-charged localized optical vortices in cubic-quintic nonlinear media
The stability of two-dimensional bright vortex solitons in a media with
focusing cubic and defocusing quintic nonlinearities is investigated
analytically and numerically. It is proved that above some critical beam powers
not only one- and two-charged but also multiple-charged stable vortex solitons
do exist. A vortex soliton occurs robust with respect to symmetry-breaking
modulational instability in the self-defocusing regime provided that its radial
profile becomes flattened, so that a self-trapped wave beam gets a pronounced
surface. It is demonstrated that the dynamics of a slightly perturbed stable
vortex soliton resembles an oscillation of a liquid stream having a surface
tension. Using the idea of sustaining effective surface tension for spatial
vortex soliton in a media with competing nonlinearities the explanation of a
suppression of the modulational instability is proposed.Comment: 4 pages, 3 figures. Submitted to Journal of Optics A. The proceedings
of the workshop NATO ARW, Kiev 2003 Singular Optics 200
Influence of overload on low-frequency instability of working process in the combustion chamber of the solid propellant rocket engine
In the paper the real oscillatory process is reproduced by statement of direct numerical experiment and the mechanism of occurrence and refill of low-frequency acoustic instability in the combustion chamber of the solid propellant rocket engine with the account of flight overload is investigated for the first time. The direct numerical modeling of low-frequency acoustic instability is carried out by means of Davydov’s method (method of large particles), which is well-suited for the solutions of many problems of mechanics of the continuous media. The results of numerical modeling are presented here. The hydrodynamic highly nonlinear nature of low-frequency fluctuations connected to structure and character of current in the combustion chamber of the rocket engine on firm fuel are proved to be tru
Influence of overload on low-frequency instability of working process in the combustion chamber of the solid propellant rocket engine
In the paper the real oscillatory process is reproduced by statement of direct numerical experiment and the mechanism of occurrence and refill of low-frequency acoustic instability in the combustion chamber of the solid propellant rocket engine with the account of flight overload is investigated for the first time. The direct numerical modeling of low-frequency acoustic instability is carried out by means of Davydov’s method (method of large particles), which is well-suited for the solutions of many problems of mechanics of the continuous media. The results of numerical modeling are presented here. The hydrodynamic highly nonlinear nature of low-frequency fluctuations connected to structure and character of current in the combustion chamber of the rocket engine on firm fuel are proved to be tru
Forecast of the dynamics of world import by commodity groups
Objective to forecast the structure and volume of world imports by commodity groups.
Methods statistical processing of global trade data with Big Data methods regression and correlation analysis.
Results the Russian economy needs to restructure exports. To solve this problem it is important to assess and forecast the global demand for certain goods. The article presents the results of the analysis of the main trends and forecasts of the development of individual industries as well as their place in the global trade. It is shown that in accordance with the forecasts of analysts there are significant prospects in the coming years in the fields of pharmaceutics automotive industry aircraft production telecommunications etc. UNCTAD data with a sample of product groups for each country were used to model the forecast demand for product groups. As a result of the trends modeling the article identifies the main product categories that will have the greatest growth in the global trade. It is established that the constructed forecasts correspond to the data of economic research and forecasts of analytical companies. The article also determines the relationship between imports of goods by country and various indicators. The indicators that are characterized by the highest level of correlation with the studied product categories are revealed. On the basis of the obtained results the conclusions are formulated about the most promising sectors for Russian exports in order to transit to a nonresource economy.
Scientific novelty the technique is developed which enables to make longterm forecasts of trade dynamics of large volumes of data.
Practical significance the results of the forecast should be used to determine the priorities of Russiarsquos industrial policy aimed at accelerated transition to a nonresource economy
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