Natalia Dudarenko

Method of forbidden regions in the dynamic system matrices root clustering problem

New criteria for root-clustering of the dynamic system matrices in multiply connected regions were presented. A concept of the forbidden region was introduced, and a generalization of the Lyapunov-Jury theorem onto the multiply connected regions was proposed. The necessary and sufficient conditions for root-clustering outside the forbidden region were established as a sequence of matrix inequalities. Construction of the conditions for root-clustering outside the frequency bands and robust root-clustering in multiply connected region was illustrated by way of examples.

A method for inertia tensors and centres of masses identification on symmetric precessions

A knowledge of the inertia tensors and centre of gravity locations of rigid bodies and rigid mechanical systems is required in precise control of motion and in many other applications whenever the dynamics of them is significantly determined by these inertia parameters. This paper presents a new method for identifying the inertia tensor and coordinates of the centre of mass of a rigid body or of a rigid mechanical system. The proposed method is based on the work-energy principle and provides high accuracy of identification even on devices with essential dissipation. The tensor and centre of gravity location are defined on a single spherical motion - symmetric precession. The paper gives a survey of existing inertia parameter identification methods, the theoretical fundamentals of the proposed identification method, the hybrid identification device and data processing procedure with error estimation on dissipative systems using proposed and classical methods.

Evaluation of two methods for reconfiguration of multivariable controllers in process control systems

In this paper two methods for the reconfiguration of multivariable decentralized controllers are evaluated for their feasibility in real life applications. As real-life case the air control system of a waste-to-energy plant in the pulp and paper industry is used. The first method is based on the factorization of the closed loop sensitivity transfer matrix and the second on degeneration factors of the closed loop system. The two candidate methods are evaluated by comparing their results with the results obtained from established interaction measures. Thereafter the reconfiguration of the control system is performed and subsequently re-assessed. The results show that both methods can be used to derive reasonable indications on how controllers can be reconfigured to achieve better performance of the closed loop system. It is also estimated that the performance of the air control system can be improved by 3% when a feed forward link is introduced in the current control structure.

Ranking algorithm by contacts priority for social communication systems

The paper presents the ranking algorithm by contacts priority with application for social communication services. This algorithm makes it possible to rank contacts in different social communication services by their priority for the user, and find a preferable communication tools for every contact in the social graph. It is proposed to determine priorities of the contacts using communication history. The ranking algorithm is based on the Markov chains theory and social strength calculation approach. The paper exploits the opportunities for measuring social strength for the contacts and also prioritizes communication tools for simplifying communication. The results are supported by an example.

Performance Evaluation of MIMO Discrete Dynamic Systems with Periodic Disturbances Using Degeneration Factors

Abstract Performance evaluation of multiple-input multiple-output (MIMO) systems needs to be a priori estimated. An algorithm of performance evaluation of MIMO discrete dynamic systems with periodic disturbances is proposed in the paper. It is based on degeneration factors that are constructed with singular values of criterion matrices of a MIMO system. The criterion matrices are created with the Sylvester matrix equation. The results are supported with an example.

Reconfiguration of the Air Control System of a Bark Boiler

In this paper, the problem of reconfiguration of controllers in the air control system of a bark boiler is addressed. The air control system of a bark boiler is considered as an interconnected multivariable system and the configuration of the controllers is adapted with the perspective to improve the closed-loop performance of the system. This paper proposes a generic procedure for the reconfiguration of controllers using a combination of established theories together with rather recently proposed methods. The procedure is applied to a model of the air flow system, which is derived in this paper. The results indicate that a significant performance improvement can be achieved by reconfiguring the control system instead of redesigning the process. The improvement is quantified through theoretical assessment, simulation studies, and performance assessment of pilot tests at the bark boiler at SCA Obbola AB, Sweden. It can be concluded that the proposed procedure is both efficient and easy to apply.

Algebraic Conditions of Generalized Modal Control

Abstract We search for algebraic conditions of generalized modal control feasibility. This kind of control ensures desired structures of eigenvalues and eigenvectors of the closed-loop system. Possible areas of generalized modal control application are indicated.

The use of Lyapunov differential inequalities for estimating the transients of mechanical systems

In this paper we consider an autonomous mechanical system in a finite neighborhood of the zero of the phase space of states. The system is given as a matrix differential equation in the Cauchy form with the right-hand side of the polynomial structure. We propose a method for constructing a sequence of linear inhomogeneous differential inequalities for Lyapunov functions. As a result, we obtain estimates of transient processes in the form of functional inequalities.

Poincare-Dulac method with Chebyshev economization in autonomous mechanical systems simulation problem

We consider an equation of an autonomous dynamical system with one degree of freedom. It contains the linear and cubic forms relative to phase variables. In order to simplify the mathematical model we use the modified asymptotic method of Poincare-Dulac conversion. Using Chebyshev approximations of high-degree polynomials with polynomials of smaller degrees we reduce the residual error. We consider non-oscillatory mechanical systems in the case of absence of internal Poincare resonances that leads to a linear form.

Control of degeneration of discrete multichannel systems with multiple discrete intervals

Discrete multichannel systems whose separate channels are characterized by discrete intervals of varying duration satisfying the multiplicity condition are considered for possible degeneration. The main result is based on the concept of reducibility of these channels to a model representation in the form of a discrete description with discrete intervals equal to half the minimum. A possibility of degeneration of discrete multichannel systems in the event of incorrect correspondence of the intensities of input fluxes to the original discrete intervals is studied. The problem is solved quantitatively by using degeneration functionals designed on the spectrum of singular values of criterial matrices.