Ervin Bauer was Hungarian and Soviet scientist, who had a short, but bright and talented life. In 1935, working at the Institute of Experimental Medicine in the USSR, he published the ...book «Theoretical Biology», in which he proposed an idea of a special “non-equilibrium” state of living systems and the existence of internal machineries in the organism that work against thermodynamic equilibrium and increase the organism's capacity for work. Currently, this idea is called “the principle of sustainable non-equilibrium” or “Bauer's principle”. During the repressions of the 1930s in the USSR, Bauer was executed, the book « Theoretical Biology» was banned. Currently, his works are poorly known, especially outside the post-socialist region. We believe that his ideas could help in rethinking not only the biochemistry and bioenergetics of cells and tissues of living organisms, but also biogeochemical and civilizational processes on a planetary scale.
Problems that reduce to consistency or inconsistency of systems of linear equations or inequalities arise in many divisions of theoretical informatics. The examples are problems in linear ...programming, machine learning, multicriteria optimization, etc. There exist different stability measures for the property of consistency or inconsistency, and different information constituents are possible (all the input parameters, the coefficient matrix, the vector of constraints). In this paper, variations of all parameters are examined in combination with an additional constraint important in applications, namely, the nonnegativity of feasible points.
Solubility of biodiesel fuel components in fossil diesel fuel–methanol–rapeseed oil methyl ester, fossil diesel fuel–ethanol–rapeseed oil methyl ester and fossil diesel fuel–ethanol–rapeseed oil ...ethyl ester systems was investigated. The solubility of components in the fossil diesel fuel–ethanol–rapeseed oil methyl ester system at 20 °C was substantially higher than in the fossil diesel fuel–methanol–rapeseed oil methyl ester system. The solubility of components in the fossil diesel fuel–ethanol–rapeseed oil ethyl ester system was slightly lower than in the fossil diesel fuel–ethanol–rapeseed oil methyl ester mixture. The moisture content of ethanol had a great influence on mixture solubility. With decrease of temperature, the solubility of components in the fossil diesel fuel–ethanol–rapeseed oil methyl ester system decreased.
Cataclysmic variables (CV) and pre-cataclysmic binaries (PCB) are discussed. The main difference between them (accretion or its absence) is shown to be a consequence of the evolutionary process and ...the properties of their progenitors. Both types of system have a bimodal distribution of their periods, but the extrema are in counterphase. Luminosity-effective temperature diagrams for the primary components are used to show that both systems have approximately the same age, which conflicts with the notion of PCBs as precursors of CVs. Calculations of the maximum distance between components for which the system remains stable show that CVs have passed this limit, while PCBs maintain their stability during this evolution. It is suggested that, after ejecting a common shell, future CVs immediately become semi-detached systems. It this is so, then there must be cataclysmic variables which are the central stars of planetary nebulae.
Several now adaptive algorithms are presented for a class of model reference, control systems. They include the commonly used adaptive law as a special case, which has the form “Proportional” plus ...“Integral” plus “Higher-order integrals.” Each algorithm works as an adaptive law which gives the stability, or the asymptotic stability under Well known assumptions. Although it is not proven mathematically that the sequence of proposed adaptive algorithms converges, simulation results show the effectiveness of the algorithms not only for a deterministic environment, but also to case of white random noise in the plant output.
•A coordinated control strategy of the converter based on the constant cut-off area;•Commutation area theory and the coupling mechanism of the system;•Improvement of transient characteristics of ...UHVDC system.
The Ultra High Voltage Direct Current (UHVDC) systems under hierarchical connection, while improving the voltage support and current assimilative capacity of the receiving-end system, also bring new challenges to the security and stability of the power grid. An AC short-circuit fault at the receiving-end system can easily induce commutation failures (CFs) of the high-end and low-end converter at the same time, which seriously affects the stability of the system. Therefore, it is urgent to study the coordinated control strategy for the commutation failures of UHVDC systems under hierarchical connection. This paper analyzes the coupling mechanism and CFs characteristics of the high-end and low-end converters of a UHVDC system under hierarchical connection. Based on the commutation area theory of the three-phase full-wave bridge circuit, a coordinated control strategy is proposed to suppress CFs of the non-faulty layer converter of the UHVDC system under hierarchical connection. It can reserve enough extinction area for the non-faulty layer converter after an AC system failure occurs, thus preventing the occurrence of commutation failure. Finally, based on PSCAD/EMTDC, Zhundong-Wannan ±1100 kV UHVDC was built and the effectiveness of the proposed control strategy was simulated and verified. The simulation results show that the proposed control strategy can effectively suppress the simultaneous commutation failure of inverter station converters when symmetrical faults and asymmetrical faults of different levels occur in the receiving-end grid. This has important engineering significance for improving the stability of the DC transmission system.
The problem of forming a rotating ring-shaped tethered system consisting of three nanosatellites is considered. To analyze the dynamics of the tether system, a mathematical model is developed in the ...orbital coordinate system using the Lagrange method. Using the sliding mode control method, two control programs for the deployment of tethers are proposed, in which tether tensions and thrust forces created by low-thrust engines are used as controls. In the first control program, the control actions are directly limited by the permissible limits of tether tensions forces and thrust forces, and when designing the second control program, an auxiliary dynamic system is added into the control system, which introduces control corrections that take into account the saturation effect. The stability of motion of the tethered formation system for both control programs is investigated using the Lyapunov theory. The results of numerical simulations confirmed the possibility of using the proposed control programs for the formation of a rotating triangular tethered system in the form of a regular triangle in the presence of disturbances and with account of the given constraints.
Abstract
In power system swing equation plays a remarkable role in investigating the transient stability. Disturbances in system creates imbalance and it may lead to lose the synchronism. Solution of ...swing equation will help the operators to analyze the stability of the system during the disturbances and initiate the protective mechanism to save the system. The non linear differential swing equation is complex in nature. Commonly used numerical methods to solve swing equations like Point by Point, Modified Euler’s and Runge Kutta have explained in the paper. Along with numerical methods, two other methods, evolutionary algorithm based Particle Swarm Optimization method and analytical based Maximum Lyapunov Exponent method has also been investigated in this paper.
In this paper, we are going to study quintom dark energy cosmological model. In that case we introduce the action of gravity which is minimally couple to scalar field
ϕ
and
σ
with potential
V
(
ϕ
,
σ
...)
. First we write the Lagrangian of corresponding model in
FRW
model. Here we also introduce the non-commutative geometry and modify the above model. The deformed model leads us to obtain the equation of state. And finally we discus the present cosmological in case of phantom and quintessence. And also, we investigate the critical point and stability of system.
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