Fluorescence polarization measurements were used to study changes in the orientation and order of different sites on actin monomers within muscle thin filaments during weak or strong binding states with myosin subfragment-1. Ghost muscle fibers were supplemented with actin monomers specifically labeled with different fluorescent probes at Cys-10, Gln-41, Lys-61, Lys-373, Cys-374, and the nucleotide binding site. We also used fluorescent phalloidin as a probe near the filament axis. Changes in the orientation of the fluorophores depend not only on the state of acto-myosin binding but also on the location of the fluorescent probes. We observed changes in polarization (i.e., orientation) for those fluorophores attached at the sites directly involved in myosin binding (and located at high radii from the filament axis) that were contrary to the fluorophores located at the sites close to the axis of thin filament. These altered probe orientations suggest that myosin binding alters the conformation of F-actin. Strong binding by myosin heads produces changes in probe orientation that are opposite to those observed during weak binding.

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An article discusses achievements in the field of real time hybrid simulation of electrical power systems and their application for smart grid tasks solution. The developed real time hybrid simulation concept and tools are introduced as an alternative to digital simulation systems that are currently widely spread. To substantiate this, the article proposes some factors determining the preference of hybrid simulation approach to numerical methods used in digital simulators. A number of accomplished projects and problems solved in the context of these projects are given to confirm the relevancy, efficiency and viability of the introduced approach of real time hybrid simulation.

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Polarized fluorimetry was used to study in ghost muscle fibers the influence of a 40-kDa protein from the thin filaments of the mussel Crenomytilus grayanus on conformational changes of F-actin modified by the fluorescent probes 1,5-IAEDANS and FITC-phalloidin during myosin subfragment (S1) binding in the absence of nucleotides and in the presence of MgADP or MgATP. The fluorescence probes were rigidly bound with actin, which made the absorption and emission dipoles of the probes sensitive to changes in the orientation and mobility of both actin monomer and its subdomain-1 in thin filaments of the muscle fiber. On modeling different intermediate states of actomyosin, the orientation and mobility of oscillators of the dyes were changed discretely, which suggests multistep changes in the actin conformation during the cycle of ATP hydrolysis. The 40-kDa protein influenced the orientation and mobility of the fluorescent probes markedly, suppressing changes in their orientation and mobility in the absence of nucleotides and in the presence of MgADP, but enhancing these changes in the presence of MgATP. The calponin-like 40-kDa protein is supposed to prevent formation of the strong binding state of actomyosin in the absence of nucleotides and in the presence of MgADP but to activate formation of this state in the presence of MgATP.

Abstract. The motivation of the presented research is based on the need for development of new methods and tools for adequate real time simulation of automation control frequency and power regulators of generator played an important role in the planning, design and operation of electric power system. This paper proposes a Hybrid real time simulator of electric power system for simulation of automation control frequency and power regulators of generator. The obtained results of experimental researches of turbine emergency control of generator demonstrate high accuracy of the simulator and possibility of real-time simulation of all the processes in the electric power system without any decomposition and limitation on their duration, and the effectiveness of the proposed simulator in solving of the design, operational and research tasks of electric power system. IntroductionAccording to the well-known reasons, the simulation of electric power system (EPS) is the only effective tool for research of processes in EPS as a whole and solving of the design, operational and research tasks, including adequate settings of relay protection and automation system (RPA) of EPS [1,2]. Therefore, accurate modeling of RPA is one of the conditions for achieving a high adequacy of simulation EPS. At the same time simulation of RPA is quite complex problem that has significant practical value and can to solve a number of tasks. There are most urgent tasks [2,3]: The analysis and optimization of calculated settings of RPA;  The formation of methods and means of adequate settings of RPA (including automatic voltage regulator (ARV), Automatic frequency and power control (known as automatic generation control (AGC)), and others;  The development of new emergency control systems of EPS, including multi-agent systems; In particular, the simulation of AGC of generator is one of the most urgent tasks [4,5]. Especially important from a researcher's viewpoint is the depth of the simulation, as well as impact of the simulation depth to adequate modeling of the processes in EPS. The main criterion for the solution of this task is ability of realization of the AGC model in the particular simulated EPS with the maximum possibility of simulation depth of AGC model. Several approaches to solving the task of adequate simulation of AGC model have been implemented during the development of Hybrid real time simulator (HRTSim) of EPS, based on the concept of hybrid simulation and developed in Tomsk Polytechnic University [6,7]. The first version of AGC model created in 1988 was developed at analog simulation level via operational amplifiers and analog multipliers. In the current version, the AGC model has been realized at digital simulation level via microcontroller, which is a coprocessor of specialized hybrid processor (SHP) of electric

Abstract. The motivation of the presented research is based on the needs for development of new methods and tools for adequate simulation of intelligent electric power systems with active-adaptive electric networks (IES) including Flexible Alternating Current Transmission System (FACTS) devices. The key requirements for the simulation were formed. The presented analysis of simulation results of IES confirms the need to use a hybrid modelling approach.

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