Last issue
2017 (vol. 27) - Number 2


W. Bozejko, M. Wodecki:

Discrete Systems: Theory and Applications. Special issue.



G. Bocewicz, Z. Banaszak, I. Nielsen:

Delivery-flow routing and scheduling subject to constraints imposed by vehicle flows in fractal-like networks



W. Bozejko, A. Gnatowski, R. Idzikowski, M. Wodecki:

Cyclic flow shop scheduling problem with two-machine cells



W. Bozejko, M. Uchronski,, Z. Chaczko, M. Wodecki:

Parallel patterns determination in solving cyclic flow shop problem with setups



J. Brodny, S. Alszer, J. Krystek, M. Tutak:

Availability analysis of selected mining machinery



K. Chmielewska, D. Formanowicz, P. Formanowicz:

The effect of cigarette smoking on endothelial damage and atherosclerosis development - modeled and analyzed using Petri nets



A. Galuszka, J. Krystek, A. Swierniak, T. Grzejszczak, C. Lungoci:

Information management in passenger traffic supporting system design as a multi-criteria discrete optimization task



M. Kardynska, J. Smieja:

Sensitivity analysis of signaling pathway models based on discrete-time measurements



J. Kasprzyk, P. Krauze, S. Budzan, J. Rzepecki:

Vibration control in semi-active suspension of the experimental off-road vehicle using information about suspension deflection



M. Koryl, D. Mazur:

Towards emergence phenomenon in business process management



M. Koryl:

Active resources concept of computation for enterprise software



H. Krawczyk, M. Nykiel:

Mobile devices and computing cloud resources allocation for interactive applications



W. Mitkowski, W. Bauer, M. Zagórowska:

Discrete-time feedback stabilization



J. Pempera:

An exact block algorithm for no-idle RPQ problem



K. Rzosinska, D. Formanowicz, P. Formanowicz:

The study of the influence of micro-environmental signals on macrophage differentiation using a quantitative Petri net based model



K. Skrzypczyk , M. Mellado:

Vehicle navigation in populated areas using predictive control with environmental uncertainty handling



W. Bozejko, J. Pempera, M. Wodecki:

A fine-grained parallel algorithm for the cyclic flexible job shop problem




ACS Abstract:

1997 (Volume 6)
Number 3/4
1. A numerically simplified fuzzy logic controller
2. Adaptive stabilization of a class of semilinear parabolic distributed parameter systems in the case of collocated actuators and sensors
3. Optimal control of distributed stochastic systems with delays in the control
4. On the dynamics of a closed-loop system with hysteresis
5. Overshoots in 2-nd class of linear control systems
6. Floating-point roundoff errors in first-order filters of digital controllers
7. The quest for small benchmarks for the chromatic sum problem
8. Circular built-in self-test for controllers with many internal clocks
9. Robustness of fuzzy control with respect to plant parameters modifications - simulation results


A numerically simplified fuzzy logic controllerDownload full PDF article
Bogdan Kasztenny, Andrzej Wiszniewski
(Wrocław University of Technology, Poland )
Constantine Hatziadoniu
(Constantine Hatziadoniu)

This paper is concerned with the numerical optimization of a Fuzzy Logic Controller (FLC) for both its efficient simulation and easy real-time implementation. The basic concept of the FLC based on generalized T-operators approach has been presented. Several assumptions regarding the mathematical formalization of the FLC have been made leading to its numerical simplification. They include: Goguen formulas for T-operators, "Center of Gravity" method for defuzzification, and the overlapping between not more than two membership functions for fuzzy output from the controller. Under these assumptions, the paper presents the non-fuzzy output from the FLC as the ratio of two weighted sums of certain functions of the inputs, reducing significantly the computational burden of the FLC algorithm comparing with the definition-based implementation. The analysis has been performed for a two-input FLC, but extended to a multi-input FLC. The Fuzzy Logic Power System Stabilizer (PSS) has been chosen as an application example. Results of simulation studies demonstrate the efficiency of both the presented optimization method in terms of numerical simplicity and the designed PSS in terms of improving the power system stability.

keywords: Fuzzy Logic Control, T-operators, Numerical Optimization, Power System Stabilizer.

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Adaptive stabilization of a class of semilinear parabolic distributed parameter systems in the case of collocated actuators and sensorsDownload full PDF article
Toshihiro Kobayashi, Jiachun Fan
(Kyushu Institute of Technology, Japan )

In this paper we consider adaptive stabilization of a class of semilinear parabolic distributed parameter systems in the case of the input and output operators being unbounded and collocated. So boundary stabilization problems can be treated. Adaptive stabilization is realized by the concept of high-gain output feedback. In the controlled system, the convergence of the system state to zero will be guaranteed.

keywords: adaptive stabilization, semilinear distributed parameter systems, collocated input and output, boundary input and output.

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Optimal control of distributed stochastic systems with delays in the controlDownload full PDF article
M. Rachik
(Faculté des Sciences Ben M'sik, Morocco )
J. Karrakchou
(Ecole Mohammadia d'Ingénieurs, Morocco )

In this paper we consider the quadratic control problem for stochastic infinite-dimensional systems with delays in the control. It is well known that, using the separation principle theorem, the problem can be reduced to two independant problems of control and filtering. The objective of this paper is to present a new approach for solving this problem when the state of system is completely observed. It is based on the introduction of an adequate Hilbertian topology. To illustrate this work, an example of controlled noisy equation is given.

keywords: Delayed control, Distributed stochastic systems, Hilbert uniqueness method, Optimal control, Separation principle theorem.

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On the dynamics of a closed-loop system with hysteresisDownload full PDF article
Andrzej Ossowski
(Institute of Fundamental Technological Research PAN, Poland )

A closed-loop hysteretic system of stabilization of a multidimensional stationary linear object is considered. The stability analysis of the system is performed by means of the second method of Lyapunov. Sufficient conditions of stability are provided and optimal estimate of the asymptotical region is obtained. Dynamical properties of the system in the region of hysteresis are described. The existence of a stable limit cycle in the region is proved.

keywords: Lyapunov function, feedback stabilization, bang-bang control, hysteresis.

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Overshoots in 2-nd class of linear control systemsDownload full PDF article
Mieczysław Zaczyk
(University of Mining and Metallurgy, Poland )

The relation between overshoots and the coefficients of the differential equations describing the system is one of the central problem of control systems. Analytical formulae for the determination of overshoots are known only for the second order systems. In the paper [6] there are presented such formulae for the 1-st class of the system it means for the systems with only one pair conjugate roots. In this paper the overshoots for the 2-nd class of the systems containing 2-pairs of the conjugate roots are determined.

keywords: control system analysis, 2-nd class of linear control systems, overshoots in linear systems.

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Floating-point roundoff errors in first-order filters of digital controllers Download full PDF article
Zbigniew Świder
(Technical University of Rzeszów, Poland )

Roundoff errors of floating-point arithmetic for first order unity-gain digital filters realized by means of z- and 'delta'-operators are evaluated. 'delta'-realization corresponds to classical analog scheme involving adder, multiplier, and integrator. It allows for much smaller sampling period than z-realization. White noise, sinusoid and a constant with small additive noise are considered as filter inputs. The third case may represent process variable in feedback control loop. It turns out that the 'delta'-realization provides twice smaller roundoff error than z-realization. An upper bound on filter time constant is given in case of process variable input.

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The quest for small benchmarks for the chromatic sum problemDownload full PDF article
W. Głazek, M. Kubale, K. Manuszewski
(Technical University of Gdańsk, Poland )

The chromatic sum of a graph is the minimum total of the colors on the vertices taken over all possible proper colorings using natural numbers. Because of practical applications and the fact that computing the chromatic sum is NP-hard, we are interested in the performance of heuristic algorithms. For a given approximate coloring algorithm a graph is said to be slightly HCT (resp. HCT) if some (resp. every) implementation of the algorithm gives a bigger total than the chromatic sum. In this paper we give the smallest HCT and slightly HCT graphs for the most popular vertex coloring algorithms when adapted to the chromatic sum problem. Some of them have been obtained by exhaustive computational search. Our results confirm that algorithms based on the independent sets principle are much better than those realizing a sequential coloring approach.

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Circular built-in self-test for controllers with many internal clocksDownload full PDF article
Michał Kope
(University of Silesia in Cieszyn, Poland )

The paper proposes a new extension to Circular Built-In Self-Test (named Multi-Clock Circular-BIST - MCC-BIST) suitable for testing controllers composed of many sequential blocks controlled by different clock signals generated in one block. Testing can be performed in one session and the need of clock line switches between normal and BIST mode is minimised. As a result both logic overhead is reduced and no additional faults in the switching circuitry are inserted. The properties are examined and simulation results of a sample controller are provided. They verify that this technique guarantees high test quality provided that the test time is increased. MCC-BIST is feasible for incorporating into IEEE1149.1 standard.

keywords: Built-In Self-Test, Pseudorandom Test, Sequential Circuit Testing

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Robustness of fuzzy control with respect to plant parameters modifications - simulation resultsDownload full PDF article
Jacek Kluska
(Rzeszow University of Technology, Poland)

A comparative study on robustness and performance of different controllers is presented. Simulation results on dependence between four basic performance indices and the plant parameters are given. The linear second order plant with time delay and the following controllers: PID, three-dimensional multilevel relay, Mamdani's fuzzy controller, fuzzy controller with G?del's implication, and the "modified" fuzzy controller, which is described in work [7], are investigated.

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