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This paper presents a method for controlling torsional vibrations in rotating machines with nonlinear dynamics. The work is motivated by rotating machines with cam or crankshaft mechanisms that generate harmonic signal components in the angular speed with respect to the rotation angle. In the system description, the torsional vibrations are modeled as disturbances acting upon a linear plant. Thus,...
The realization of adaptive-based controllers in many industrial control applications may exhibit the parametric drift behavior acquiring the well known bursting phenomenon. In this work, an original and novel technique is proposed to eliminate this phenomenon. It is based on a modification of the discrete-time delta modulator into its continuous-time domain and then by adding hysteresis. To verify...
A novel approach to simulation of communication channel in the presence of intersymbol interference is introduced in the paper. The distinctive feature of the approach is accurate defining of information parameter at the output of communication channel. A new model for additive white Gaussian noise is presented.
Coherent hemodynamics spectroscopy (CHS) is a novel method based on the frequency-resolved study of induced hemodynamic oscillations in living tissues. Approaches to induce hemodynamic oscillations in human subjects include paced breathing and cyclic thigh cuff inflation. Such induced hemodynamic oscillations result in coherent oscillations of oxy-, deoxy-, and total hemoglobin concentrations in tissue,...
An efficient perturbation projection vector (PPV) modeling for a memristor-based oscillator is proposed and then applied to the simulation of the oscillatory neural network (ONN) for pattern recognition. Compared with the existing model, which is very time consuming, this novel modeling method features a fast and accurate simulation of a large-scale network with many oscillators. The proposed modeling...
Intra-annual and multi-decadal variations in the Earth's climate are to a large extent driven by periodic oscillations in the coupled state of atmosphere and ocean. Because changes in climate impact terrestrial ecosystems, these ocean-atmospheric oscillations are expected to influence land evaporation as well. In this study, we investigate the control of ocean-atmospheric oscillations over global...
The results of the test of numerical methods for solving systems of differential equations describing the system with a complex and chaotic dynamics are discussed. Discusses the results of numerical solution of differential equations based on microwave oscillator equivalent circuit in various dynamic modes. The quantitative evaluation of the actual, global and the mean square error of the numerical...
This paper exploits Duffing equation and discusses some numerical methods to solve it. Numerical calculation's errors of the amplitude and the period of free oscillations of a large time interval of codes TR, BDF, and RADAU5 are computed. Publications describe a plurality of stiff test problems. The highly oscillating problems is known much less. Duffing equation can serve as test concurrently stiff...
Generally in power system the vibrant power and current constraint will vary by the subject of generators and it addresses the deviations by rearrangement process. The major aspire of the development is to sort out the requirement of vibrant power load. The generator excitation loop will tune the dynamic power trigger by the maximum value of electricity over the network. By the link of stabilizer...
Mechanisms of spatiotemporal localization of femtosecond powerful pulses, the problems and conditions of light bullets (LB) stability, being key issues for many applications, nowadays remain challenging and largely unresolved tasks. Therefore these questions attract much attention of scientists. As is known, in Kerr media the filamentation makes possible the generation of spatially and temporally...
We consider a mechanical system with mixed spectrum of natural oscillations. This is an infinite string on the Winkler elastic foundation with point inhomogeneity (the spring with negative stiffness). The discrete part of the spectrum contains a unique positive eigenvalue that corresponds to a trapped mode of oscillation. The aim of the paper is to describe evolution of the amplitude of the trapped...
A new simple two-transistor four-dimensional (4D) chaotic oscillator is proposed using two sub-circuits, i.e. a modified single-transistor Colpitts oscillator, and another singletransistor sub-circuit for the fourth dimension. The circuit is much simpler than two existing two-transistor 4D chaotic circuits, as it has only nine electronic components, and only eleven algebraic terms in the state equation...
Paper deals with digital generating quadrature wave, their measurement and monitoring using Lab View virtual instrumentation system. Beside classical triangular digital quadrature oscillator there are investigated rectangular- and meander-type waveforms and also three-phase Clarke transformed orthogonal waveforms. There is shown — using digital computation of total harmonic distortion — that meander-type...
This paper presents further development of the cascaded gradient extremum seeking control loop design. Such closed loop consists of two cascades. The inner cascade includes the dynamical part of a plant, while the outer cascade works with an extremum characteristic. The frequently used synchronous detector method is applied as gradient evaluation mechanism, but its technical realization is nonstandard...
The heliocentric motion of the solar sail spacecraft (SSS) is described in classical Keplerian elements. The solar sail with an ideal reflection coefficient is considered. The spacecraft performs a non-coplanar motion with the sun gravity and the light pressure. Disturbances of other celestial bodies gravity are not considered. To confirm the results correctness, we simulated the motion of solar sail...
Virtual synchronous generator (VSG) has been developed recent years as a promising grid-tied inverter control strategy because it can improve the penetration of the renewable energy. Due to introducing virtual inertia, the active power loop of VSG behaves as a typical second-order system, which may cause active power oscillation. It is a key issue that designing the parameters of active power control...
Exact linearization is often applied to nonlinear processes. This method requires not only the knowledge of the model structure but also the accurate parameter values. If the real parameter values of the controlled process are different from the nominal values used for the exact linearization, the resulting system may not be linear or may have different gains and time constants as expected. A simple...
This paper presents two approaches to model the startup behavior of cross-coupled oscillators for regenerative sampling applications. The first approach closely models the building blocks and connections of the circuit at the device level, whereas the second approach uses an equivalent model based on the analysis of the differential currents in the circuit to simplify the calculation and obtain a...
Power system stabilizers (PSSs) are generally used to damp low frequency oscillations. Usually, a classical PSS uses a fixed, second-order model, for which a mere tuning of its parameters is required. These controllers have been implemented successfully for many years. However, conventional PSSs may become inadequate when the operating conditions of the system are changing widely, because of the lack...
The aim of this research work is to analyse sub-synchronous control interaction (SSCI) in doubly-fed induction generators (DFIGs) and to design a supplementary control technique for the mitigation of SSCI. A mathematical model of the DFIG is derived and linearized in order to perform an eigenvalue analysis. This analysis pinpoints the parameters of the system which are sensitive in making sub-synchronous...
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