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GENERATION OF MAGNETIC FIELDS IN COSMOLOGICAL SHOCKS
MEDVEDEV MIKHAIL V.,SILVA LUIS O.,FIORE MASSIMILIANO,FONSECA RICARDO A.,MORI WARREN B. The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.5
The origin of magnetic fields in the universe remains an outstanding problem in cosmology. We propose that these fields are produced by shocks during the large-scale structure formation. We discuss the mechanism of the field generation via the counter-streaming (Weibel) instability. We also show that these Weibel-generated fields are long-lived and weakly coupled to dissipation. Subsequent field amplification by the intra-cluster turbulence may also take place, thus maintaining the magnetic energy density close to equipartition.
Basic Algorithms of Adaptive Position-path Control Systems for Mobile Units
V. Pshikhopov,M. Medvedev,B. Gurenko,M. Beresnev 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
Today, mobile objects are finding increasing usage in a wide variety of applications. Robots have been put to use in the air, on the ground and under the sea. Along with this expansion in robot technology, the problem of control and autonomous decision making is an ongoing concern, especially in light of the increasing difficulty of tasks. This study is focused on the algorithms of adaptive control system for mobile objects. The authors examined the application of direct adaptive control with reference to model approaches, in particular the position-path method. Point positioning is discussed, and the authors propose a method for efficiency improvement. Parametric uncertainty and influence of immeasurable disturbances are expected. Basic algorithms for the calculation of controlling forces and moments are synthesized using the position-path control method. The authors propose a structure and algorithms of an adaptive position-path system with a reference model. The synthesis of adaptive regulator and stability analysis of closed-loop system is performed, and an example of regulator synthesis is given. Finally, the authors present simulation results for an autonomous unmanned underwater vehicle equipped with a main engine, nose and hydrodynamic rudders on the tail. Along with this, horizontal and vertical maneuvering devices are presented.
( Maurizio Bussolo ),( Denis Medvedev ) 세종대학교 경제통합연구소 (구 세종대학교 국제경제연구소) 2008 Journal of Economic Integration Vol.23 No.3
Econometric analysis established a negative relationship between labor supply and remittances in Jamaica. We incorporate this ex-post evidence in a general equilibrium model to investigate economy-wide effects of increased remittance inflows. In this model, remittances reduce labor force participation by increasing reservation wages of recipients. This exacerbates the real exchange rate appreciation, hurting Jamaica`s export base and small manufacturing importcompeting sector. Within the narrow margins of maneuver of a highly indebted government, we show that a revenue-neutral policy response of a simultaneous reduction in payroll taxes and increase in sales taxes can effectively counteract these potentially worrisome effects of remittances.
Path Planning for a Group of Vehicles in 2D Obstructed Environment
Pshikhopov V.Kh.,Medvedev M.Y.,Shevchenko, V.A. 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10
Path planning problem for a vehicle group in a two-dimensional obstructed environment is addressed. The kinematics equations of the vehicles on a plane with ideal connections are considered. Then a method is proposed for planning motion paths based on the interpretation of all the neighboring objects as repellers. The method on the basis of simple algorithms implemented in design of vehicles enables organization of the group motion without using a centralized algorithm. A new method for introduction of repellers which is based on formation of an unstable position in the vehicles phase space is proposed. Repulsive forces are generated as outputs of dynamic elements that integrate non-linear functions of the distance to the obstacles. As a result, we obtained the principles of changing speed and direction of the vehicles’ motion. The stability analysis of the obtained paths was made using the method of Lyapunov functions. We showed steady state regime of a group of vehicles and its asymptotic stability. Modification of the planning algorithm with no setting of the trajectory is being proposed. The developed algorithms are implemented within a decentralized structure of the control system. Numerical modeling of a goup of five robots in an environment with stationary obstacles was carried out. Conclusions were made about using the proposed method in practice based on this analysis and the modeling results. A modification of this path planning method is being discussed - the one that uses kinematics equations and dynamics equations; this allows to take into consideration the speed of approaching to the obstacles. Also using this method in three-dimensional environment and in an environment with nonstationary obstacles is being discussed.