Transient Cherenkov radiation from an inhomogeneous string excited by an ultrashort laser pulse at superluminal velocity

An optical response of one-dimensional string made of dipoles with a periodically varying density excited by a spot of light moving along the string at the superluminal (sub-luminal) velocity is theoretically studied. The Cherenkov radiation in such system is rather unusual, possessing both transient and resonant character. We show that under certain conditions, in addition to the resonant Cherenkov peak another Doppler-like frequency appears in the radiation spectrum. Both linear (small-signal) and nonlinear regimes as well as different string topologies are considered.Comment: accepted to Phys. Rev.

REGULATORY ASPECTS OF AGRIBUSINESS ENTITIES DEVELOPMENT

The authors presents the system representation of the process of interaction between the state and the subjects of agricultural production, supplemented by the block of regulation of the development of large, medium and small agricultural farms. The methodical approach of determination of economic eciency of measures of the state it allows to take into account and use in the right direction the factors of inuence of exogenous impacts, which are dicult controlled by business. It is proposed to improve the mechanism of state support, to orient the expenses of budget expenditures on the formation of the nal result. The criteria of the nal result is proposed to supplement the indicator of social eect - the number of jobs created and additional budget revenue

Modeling the burnout of solid polydisperse fuel under the conditions of external heat transfer

A self-similar burnout mode of solid polydisperse fuel is considered taking into consideration heat transfer between fuel particles, gases, and combustion chamber walls. A polydisperse composition of fuel is taken into account by introducing particle distribution functions by radiuses obtained for the kinetic and diffusion combustion modes. Equations for calculating the temperatures of particles and gases are presented, which are written for particles average with respect to their distribution functions by radiuses taking into account the fuel burnout ratio. The proposed equations take into consideration the influence of fuel composition, air excess factor, and gas recirculation ratio. Calculated graphs depicting the variation of particle and gas temperatures, and the fuel burnout ratio are presented for an anthracite-fired boiler. © 2013 Pleiades Publishing, Inc

Mathematical description of electromechanical processes with energy-efficient electric induction motor in transient conditions

Для энергосберегающего асинхронного электропривода с компенсационной обмоткой получена преобразованная схема замещения с эквивалентными параметрами намагничивающего контура. Показано, что при определенных значениях емкости компенсирующего конденсатора cosφ ≤ 1. Дано математическое описание динамических режимов преобразованного двигателя с использованием метода пространственных векторов. Разработанная структурная схема и модель электропривода позволяет произвести качественную и количественную оценку динамических режимов.For energy-efficient asynchronous electric drive with compensation winding get converted to the equivalent circuit equivalent parameters of the magnetizing circuit. It is shown that for certain values of the compensating capacitor capacitance cosφ ≤ 1. The mathematical description of dynamical regimes Engine converted using the space vector. The block diagram of the model and allows the drive to produce qualitative and quantitative assessment of dynamic modes

Investigation of surface adhesion produced by high-speed flame spraying

Peculiarities of surface adhesion based on nickel, produced by high-velocity spraying on steel base with different surface morphology have been analysed. It is shown that ultrasound final polishing builds up wavy submicrorelief providing the reliable adhesive connection between covering and base. Ultrasound finite polishing is suggested as a method of preparing surface for high-speed flame

THE DEVELOPMENT TRENDS OF REGIONAL AGRICULTURAL PRODUCTION

The problematic trends of the main factors of agricultural raw materials production have been considered. The high volatility of volume indicators, the lack of correlation between the profitability of business and product output have been noted. It has been concluded, that the current dynamics of cost indicators is largely determined by the market conditions of products and resources, and not by the processes of the producers themselves, the general trend of growth of profitability remains at low levels. Regional structural changes of branch production by types of products, the reasons of decrease in production of animal products have been shown. There difficulties with the production of forage crops, beef, pork, sunflower, lack of own funds, high accounts payable of producers have been noted. It has been proposed to increase the role of state participation in the creation of an effective business environment