2018 (vol. 28) - Number 4

*T. Kaczorek:*

A new method for computation of positive realizations of fractional linear continuous-time systems

*A. Biswas, A. Sarkar:*

Development of dual hesitant fuzzy prioritized operators based on Einstein operations with their application to multi-criteria group decision making

*L. Li, R. Zhang, J. Wang, X. Shang:*

Some q-orthopair linguistic Heronian mean operators with their application to multi-attribute group decision making

*J. Duda:*

Lyapunov matrices approach to the parametric optimization of a system with two delays and a PD controller

*M. Lhous, M. Rachik, El M. Magri:*

Ideal observability for bilinear discrete-time systems with and without delays in observation

*P.T. Anh, A. Babiarz, A. Czornik, M. Niezabitowski:*

Variation of constant formulas for fractional difference equations

*K. Bingi, R. Ibrahim, M. Noh Karsiti, S. Miya Hassan, V. Rajah Harindran:*

A comparative study of 2DOF PID and 2DOF fractional order PID controllers on a class of unstable systems

ACS Abstract:

**2013 (Volume 23)**

Number 4

Investigation of probability density functions in modeling sample distribution of surface electromyographic (sEMG) signals

I.G. Rosa, M.A.C. Garcia, M.N. Souza(Universidade Federal do Rio de Janeiro, Brazil) |

The surface electromyography signal (sEMG) has been typically modeled as a Gaussian random process. However, some authors have reported that the probability density functions (pdfs) associated with the sample distribution of sEMG signal exhibits a more peaked shape than one could expected for a Gaussian pdf. This work aimed to reinvestigate the profile of the sEMG pdfs during five different load levels of isometric contractions of biceps brachii muscle, and compared the adequacy of four different pdfs (Gaussian, Logistic, Cauchy, and Laplacian) in describing the sample distribution of such signal. Experimental pdfs were estimated for each subject and load condition. The comparison between experimental pdfs obtained from sEMG data of forty volunteers and four theoretical pdfs was performed by fitting these functions to its experimental counterpart, and using a mean absolute errors in the assessment of the best fit. On average, the Logistic pdf seemed to be the best one to describe the sample distribution of sEMG signal, although the probabilistic results, considering binomial trials, were significant for both Gaussian and Logistic pdfs.

**keywords:** electromyography, EMG, surface EMG, sEMG, EMG onset detection

Evolutionary computing approaches to optimum design of fuzzy logic controller for a flexible robot system

B. Subudhi, S. Ranasingh(National Institute of Technology, Rourkela, India) |

This paper presents the design of a Fuzzy Logic Controller (FLC) whose parameters are optimized by using Genetic Algorithm (GA) and Bacteria Foraging Optimization (BFO) for tip position control of a single link flexible manipulator. The proposed FLC is designed by minimizing the fitness function, which is defined as a function of tip position error, through GA and BFO optimization algorithms achieving perfect tip position tracking of the single link flexible manipulator. Then the tip position responses obtained by using both the above controllers are compared to suggest the best controller for the tip position tracking.

**keywords:** flexible manipulator, fuzzy logic, genetic algorithm, bacteria foraging optimization, tip position tracking

On adhesive binding optimization of elastic homogeneous rod to a fixed rigid base as a control problem by coefficient

S.H. Jilavyan, A.Zh. Khurshudyan, A.S. Sarkisyan(Yerevan State University, Yerevan, Armenia) |

The problem of finite, partially glued to a fixed rigid base rod longitudinal vibrations damping by optimizing adhesive structural topology is investigated. Vibrations of the rod are caused by external load, concentrated on free end of the rod, the other end of which is elastically clamped. The problem is mathematically formulated as a boundary-value problem for one-dimensional wave equation with attenuation and variable controlled coefficient. The intensity of adhesion distribution function is taken as optimality criterion to be minimized. Structure of adhesion layer, optimal in that sense, is obtained as a piecewise-constant function. Using Fourier real generalized integral transform, the problem of unknown function determination is reduced to determination of certain switching points from a system of nonlinear, in general, complex equations. Some particular cases are considered.

**keywords:** topology optimization, optimal design, control by coefficient, nonlinear moments problem, adhesive binding

MULTI-EDIP - an intelligent software package for computer-aided multivariate signal and system identification

J. Kasprzyk, J. Figwer(Silesian University of Technology, Gliwice, Poland) |

In the paper an intelligent software package MULTI-EDIP for computer-aided identification of multivariate signals and systems is presented. Purposes and main requirements for computer-aided identification are discussed. A summary of the most important MULTI-EDIP services with a focus on expert advice is described. An example of using the package in electro-acoustic plant identification for active noise control system development is presented.

**keywords:** computer-aided system identification, parametric model identification, nonparametric model identification, digital signal processing

Levy flights in binary optimization

M. Klimt, J. Kukal, M. Mojzes(Czech Technical University, Prague, Czech Republic) |

There are many optimization heuristics which involves mutation operator. Reducing them to binary optimization allows to study properties of binary mutation operator. Modern heuristics yield from Levy flights behavior, which is a bridge between local search and random shooting in binary space. The paper is oriented to statistical analysis of binary mutation with Levy flight inside and Quantum Tunneling heuristics.

**keywords:** binary optimization, mutation operator, Levy flights, Bernoulli trials, Quantum Tunneling

Comparison of state feedback and PID control of pressurizer water level in nuclear power plant

M. Czaplinski, P. Sokolski, K. Duzinkiewicz, R. Piotrowski, T. Rutkowski(Gdansk University of Technology, Gdansk, Poland) |

The pressurizer water level control system in nuclear power plant with pressurized water reactor (PWR) is responsible for coolant mass balance. The main control goal is to stabilize the water level at a reference value and to suppress the effect of time-varying disturbances (e.g. coolant leakage in primary circuit pipeline system). In the process of PWR power plant operation incorrect water level may disturb pressure control or may cause damage to electric heaters which could threaten plant security and stability. In modern reactors standard PID controllers are used to control water level in a pressurizer. This paper describes the performance of state feedback integral controller (SFIC) with reduced-order Luenberger state observer designed for water level control in a pressurizer and compares it to the standard PID controller. All steps from modeling of a pressurizer through control design to implementation and simulation testing in Matlab/Simulink environment are detailed in the paper.

**keywords:** nuclear power plant, pressurizer, state feedback, water level control, integral control, reduced-order Luenberger state observer, PID control

Feedback saddle point equilibria for soft-constrained zero-sum linear quadratic descriptor differential game

M.W. Musthofa, Salmah, A. Suparwanto(Universitas Gadjah Mada, Indonesia) | J.C. Engwerda(Tilburg University, Tilburg, The Netherlands) |

In this paper the feedback saddle point equilibria of soft-constrained zero-sum linear quadratic differential games for descriptor systems that have index one will be studied for a finite and infinite planning horizon. Both necessary and sufficient conditions for the existence of a feedback saddle point equilibrium are considered.

**keywords:** soft-constrained zero-sum linear quadratic differential game, feedback information structure, descriptor systems

Control methods for PWM rectifier cooperating with variable speed PM generator

W. Mazgaj, Z. Szular, T. Wegiel(Cracow University of Technology, Cracow, Poland) |

The paper deals with cooperation between pulse width modulation (PWM) rectifier and variable speed synchronous generator which is applied especially in small water or wind plants. In such applications, the synchronous generator, which is usually permanent magnet (PM) generator, rotates at a variable speed which depends on water or wind energy. Therefore, this energy should be converted to the parameters of the three-phase power grid with the use of a power electronic unit. The main aim of the control strategy is to transfer a maximum possible amount of energy produced by the water turbine or the wind turbine connected to a synchronous generator. The second purpose of the control method is to decrease the amount of higher harmonics of generator currents. The paper describes two basic methods which are used in control systems of the PWM rectifiers. The first one is the sinusoidal PWM method, and the second method relates to the hysteresis switching of the PWM rectifier transistors. A significant part of the paper is devoted to control principles of the PWM rectifier which cooperates with a variable speed PM synchronous generator. Special attention is paid to higher harmonics of PM generator currents with respect to individual methods.

**keywords:** PM synchronous generator, PWM rectifier, sinusoidal PWM method, hysteresis control method, higher harmonics

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