AVTOMATICA & INFORMATICA

 
 

1998

 

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1/1998

Some Tendencies in Development of Theory and Applications of Variable Structure Control

T. Pencheva, Tz. Georgiev, S. Tzonkov

Key Words: Variable structure systems; sliding mode; fuzzy controller; genetic algorithm; distributed parameter systems.

Abstract. In few last years there is a big interest in the field of theory and application of variable structure systems (VSS). Development of theory and applications of VSS supply quasiinvariety to outside and parameter unstationarity, using of boundary gain coefficients in close loops and practical application. In last years the theory of VSS is updated with methods of theory of fuzzy sets (fuzzy logical controllers), genetic algorithms and theory of distributed parameter systems.

 

Modification of the Evolution Strategy Method with Uses One Dimentional Interpolation Seek

I. Iliev

Key Words: Optimisation; random nonlinear adaptable direct search; revine-shaped objective function of several variables; evolution strategy; mini-max function.

Abstract. The most mini-max task for optimisation has revine-shaped objective functions. In the work is presented new modification of a stochastic multidimensional method ”Evolution Strategy”. That modification uses undimentional interpolation algorithm and has a good convergence speed in optimisation of multidimensional ravine-shaped objective functions.

 

A Procedure for Robust Design of PID Controllers

G. Elenkov

Key Words: Control system design; robustness; PID controller.

Abstract. A procedure for a robust design of PID controllers is proposed. It is based on the internal model structure approach of M. Morari. A special attention is paid to the influence of the function, which determines the place of the performance bound of the band “permitted” for the magnitude of the open loop. The idea is to determine precisely the value of the time constant of this function in accordance with the desired accuracy of the control system and plant parameters.

 

Iterative Modeling in Nonrecursive Digital Filter Synthesis

G. Iliev, I. Shishmanov, M. Momchedjikov

Key Words: Digital filters; iterative modeling; synthesis of digital filters.

Abstract. In this work an algorithm for design of nonrecursive digital filters is presented. The algorithm is based on the iterative modeling and Wiener-Hopf equation for optimal weight vector of the linear combiner. The main advantage of the algorithm is the possibility for synthesis of filters with gain magnitude characteristics different from the classic low-pass, high-pass and bandpass designs. The designed filters have linear phase characteristic.

 

Program System for Processing of Data in Information-measurement Systems

Z. Nenova, S. Manev

Key Words: Information-measurement systems; pattern recognition; digital processing; program system.

Abstract.In this work program system OBSERVER is proposed, realising processing and visualization of data designed for IBM/PC/XT/AT computers. This system includes program modules for pattern recognition, fast Fourier transformation (FFT), correlation function computation, digital filtration, interpolation, approximation and solving of systems of linear equations. These methods can be successfully used in systems for measurement and control as well as in solving research problems.

 

Problems in Using Information Systems in Bulgaria

E. Radev

Key Words: Management information systems; information utilizing.

Abstract. The statistics used in the article is extracted from a preliminary research for the country, based on a random sample, structured by regions for branch and territorial principles, by company size (list of employees) and kind of property. The purpose of the research was to asses the current state of the hardware/software base of the information supply for the needs of the decision-making process.

2/1998

Integration of Neural Networks in Automatic Control Systems

T. Atanasova

Key Words: Neural networks; control systems; adaptive control.

Abstract. Neural networks techniques have been found to be useful for controlling highly uncertain, non-linear and complex systems. The possibility of applying neural networks modeling of unknown functions in dynamic environments has been demonstrated by several empirical studies. Allowing unknown non-linearities in the system to be controlled extends the class of uncertain systems that adaptive control techniques can be applied to. In the paper an integration of neural networks in control systems is considered. Neural network application schemes are described. Some advantages and problems of neural modelling and control are presented.

 

Adaptive Multiple Model Algorithms for Estimation and Control of Stochastic Systems

N. Madjarov, L. Mihaylova

Key Words: Multiple model estimation and control; adaptive filtering; adaptive control; noise and parameter uncertainty.

Abstract. Multiple model algorithms for Kalman filtering and state regulation of stochastic systems are described in the presence of parametric model and noise uncertainty. The multiple model filter and regulator are designed as weighted sums of filters and regulators, synthesised for each model that takes part into the algorithm. The weighting coefficients are being computed on-line on the basis of measurable information. Results from simulation experiments are given.

 

Test Pattern Generation Using Boolean Satisfiability

E. Gizdarski

Key Words: Test pattern generation; Boolean satisfiability; stuck-at faults detection; redundancy identification.

Abstract. Herein an efficient algorithm for test pattern generation and redundancy identification for combination circuits is presented. It is based on Boolean satifiability method, 9-V composite algebra, an implication graph as well as iterative and recursive learning techniques. The resultant ATPG tool SPIRIT (Satisfiability Problem Implementation for Redundancy Identification and Testing) is able to generate a complete test set and prove all redundant faults within 30 seconds for each circuit in ISCAS’85 benchmark set and within 4 minutes for each circuit up to S15850 in ISCAS’89 benchmark set by PC-Pentium 133MHz/16MB.

 

C urrent Control of an Asynchronous Motor by a Microprocessor System

P. Manoilov, G. Georgiev

Key Words: Asynchronous motor; individual current control loops; field orientation; microprocessor system.

Abstract. In this paper a preliminary project of an asynchronous motor current control based on a microprocessor system is described. The process of control is accomplished within a coordinate system turning with the synchronous field and oriented on the rotor flux. The two components of the stator current and are controlled separately. The winding speed does not affect the operation of the controllers. Some of the phase components of the stator current can be computed by a suitable hardware.

 

A Servoloop for Coordinates-digital Control Programmes Based on Personal Computer

K. Kralev, K. Krustev

Key Words: CNC; personal computer; servoloop.

Abstract. In this paper a servoloop for digital control programmes based on personal computer is represented. The servoloop block diagrams are also given. The peculiarities of its programme and apparatus realization are characterized. The experimental results obtained by the servoloop applying for position control of DC motor are represented

 

3/1998

Parallel Computer Systems and Tools
for Monitoring, Tuning and Visualisation

D. Todorova

Key Words: Parallel architectures; monitoring; tuning, visualisation; integration of programming environments.

Abstract. The purpose of this paper is to give an overview of contemporary performance analysis tools. A measure-modify approach to performance evaluation is compared with analytical modeling and simulation. There are discussions about the three stages in the design of tuning tools: performance data collection; performance data filtering, and performance data visualisation. We illustrate several visualisation displays found in a number of tuning tools. In the last section we summarise the possibilities for integration of programming environments and performance tools suitable for parallel architectures.

 

Integral Transform of Images, Invariable about Translation, Rotation and Change of Size

O. Zhelezov

Key Words: Invariable transform; image recognition.

Abstract: In the report is offers one transform, that is invariable about translation, rotation and change of size of images. The purposes of the transform is to be used for the image recognition. The transform uses the invariabless of the Fourier Transform’s module about translation. The invariabless about rotation and change of size is attain with the transform of Fourier Transform’s module, so that the rotation and change of size of the given image are transforms to the translations in the received image. Then the Fourier Transform’s module of the received image will be invariable not only about translation, but and about rotation and change of size.

 

Robust Mimo Control of Continuous Fermentation Process

S. Stoyanov

Key Words: Fermentation process; nonlinear model; interval parameters; robust control; simulation.

Abstract. The paper deals with robust Multiple-Input-Multiple-Output (MIMO) control of continuous fermentation procesess. For the design purposes the nonlinear model of the process is transformed into linear one with interval parameters. Robust state space compensator is designed by the intenal model principle. Simulation studies with the nonlinear model were performed.

 

Network Flow Approach for Inductive Probabilistic Reasoning

V. Sgurev, V. Jotsov

Key Words: Inductive reasoning; network flow.

Abstract. The paper discusses a network flow approach for the selection of one hypothesis among a set of mutually contradicting hypotheses with the help of inductive probabilistic reasoning. The frequency probabilistic estimates of the separate hypotheses are formed by scientific teams in discrete time moments on the basis of one and the same experimental data. A network flow method is suggested for interpretation of the Inductive Probabilistic Reasoning class described, in which a network and a flow on it are constructed in an appropriate way. The selection of a hypothesis with better probabilistic indicators is realized by exact quantitative methods and reduced to a flow programming optimization problem.

 

A System for Machine-Aided Translation NAS 2.0

N. Serguiev

KeyWords: Machine translation; machine-ided translation.

Abstract. An environment is described for the translation from English into Bulgarian, of the Machine-Aided Human Translation type. The environment allows parallel work with a set of dictionaries, which can be hierarchically connected (the language kernel being of lowest priority ­ dictionaries for specific object areas having higher priority). The existing model for performing the translation procedure is as follows: Buffer of the text to be translated -> Modules for morphological and partial syntactic analysis (used to arrive at the NECESSARY TRANSLATION INFORMATION, to be offered later to the human translator) -> Buffer for in-between results from the search of translation equivalents -> Buffer of the already translated text. Included sources for information extraction are ordinary and specialized monolingual and bilingual dictionaries, general dictionaries, additional information following affix processing and information derived from the grammar base, used for processing grammatical structures.

 

Integrated Software Environment: an Approach for Interactive Training on Electronics and Electrotechnics

D. M. Diab

Key Words: Computer in education; computer aided learning.

Abstract. The objective of the present paper is to design an integrated interactive invironment. To design an interface between EWB, ORCAD/SDT, PCB,which represent an excellent aid to obtain printed circuit board for any electronic circuit.

 

4/1998

Using Information Technology in the Cultural Heritage Domain

Florin-Gheorghe Filip, Dan Alexandru Dociulescu,Carmen Sauer

Key words business processes, cultural heritage, information technology, library, museum, social impact, simulation.

Abstract. Recent developments in the applications of the modern ITs to the cultural heritage domain apparently indicate a synergetic interaction between the technology push and market pull (which is stimulated by governmental actions and citizen’s aspirations). This paper proposes a vision for a transition to complex systems combining IT organisations and cultural institutions. It describes the impact and limits and proposes a preliminary mathematical model to study the relationship between the organisations implied. The paper also presents specific example concerning the Romanian situation.

 

Network Flow Interpretation of Lucasevic Logic System

M. Nikolova

Key Words: Many-valued logic; network flows; graph theory.

Abstract. A method for network flow interpretation of Lucasevic many-valued logic is represented in the paper. A linear flow model of the logical negation and nonlinear flow models of the implication, the disjunction and the conjunction in Lucasevic logic are suggested. The results obtained give the possibility to define the truth of these logical operations with the help of exact qualitative methods of the operational research.

 

Basis of Reflexive Behaviors for Mobile Robot Control

O. Manolov, S. Noikov, G. Georgiev, D. Janglova, L. Uher, S. Vagner

Key Words: Hierarchical control; autonomous robot; robot navigation; path planning; robot sensors.

Abstract. In this paper one approach to the local control of tricycle mobile robots is described. AURO (AUtonomous mobile RObot) and LAMOR (Laboratory Autonomous MObile Robot ) construction and architecture of control system which combines a low level reflexive behavior with a high level path planner for the motion of mobile robot in an partially known environment are presented. The technique and the working principle of the reflexive module will be explained and an example illustrating reflexive behavior is presented too.

 

Fast Selection of Objects in Monochrome 2D Images for Image Pattern Recognition

P. Rashev, M. Lazarov, Y. Asenov

Key Words: Image processing; image pattern recognition; structural image recognition.

Abstract. The presented method allows fast selection of objects in monochrome 2D-images using basic estimations and dynamic calculation of edges over x and y axis. This method is more efficient than classic methods using digital filters. The precision of object definition herein is higher than that of methods using binary image representation. The method is suitable for images with small object area compared to background. It is invariant with changes of the scenery lighting and translation of objects.

 

Transforming an Object-Oriented Data Model into a Relational Database

M. Marinov

Key Words: Object-oriented data model; relational data model; relational database.

Abstract. Transforming the object-oriented conceptual data model into a relational database was caused by the limitations of the relational model and the imperfection of object-oriented databases. A comparative analysis of the relational and object models has been presented and the main alterations for transforming the object-oriented data model into a relational database have been suggested.

 

Fuzzy Process Control by Neural Network Surface

S. Yordanova, V. Stanchev

Key Words: Fuzzy control surface; two-layer non-linear neural network; boiler pressure control; simulation.

Abstract. A fuzzy control strategy is developed based on a fuzzy control surface. The implementation of the fuzzy surface via trained beforehand neural network substitutes interpolation procedures. The fuzzy control strategy is applied for the control of the output pressure of a boiler and tested by simulation. The step responses to changes in reference and load are more smooth and faster compared to the responses of an ordinary system with a PI-controller and their performance is preserved when the order of the plant is increased. Besides the control action is more smooth and therefore more economic and safe for the valve.

5-6/1998

Automatic Speech Recognition Systems

R. Ivanov

Key Words: ASR; speech analysis; speech recognition.

Abstract: This survey presents uptodate trends in the field of automatic speech recognition and speech analysis: statistical, physiological, perceptual, auditory based. Application of ANN and fuzzy logic in ASR systems is shown.

 

Classification of Satellite Remote Sensing Data Using Multilayered Neural Network

G. Gotchev, M. Lazarova

Key Words: Remote sensing; neural network; image interpretation and classification

Abstract. The problem for classification of satellite images received by remote sensing of the Earth is discussed in this paper. Multilayered feed-forward neural network (NN) is proposed for image classification problem. Error backpropagation learning algorithm is used for NN training. The network is trained to recognise the ground cover type of small earth area based on the multi-spectral data for the relevant pixel from the digital satellite images. Satellite data of an Earth scene are classified by the trained NN into several ground cover categories to form a thematic map. NN training and testing are performed using remotely sensed images from Landsat TM satellite for Sofia region.

 

Generalisation of the Weibull Distribution of Bandlimited Input Data on Failure Times

A. Andonova

Key Words: Data analysis; Weibull distribution

Abstract. A modified version of Weibull distribution is presented to meet the problem of bandlimited input data on failure times. This yields a more pessimistic mean time between failure value that is more realistic in case of lack of information. The use of the distribution for lifetime modeling of a bathtub type distribution is demonstrated using experimental data.

 

An Algorithm of Manipulating Sampling Data Sequences Based on Complex Key of Searching

P. Panteleev

Key Words: Sequental searching technique; sorting algorithm; pH monitoring; data sampling; key of searching.

Abstract. A development of elementary methods for searching at management of great numeric lists of chained data-linked lists. An algorithm was built on principies of sequental searching, enabling creation of various programs that handle more complicated records and keys ­ up to four. As the conditions of sorting may be very complex, the inserting, searching and initialization are performed by a function, that is called once. The keys that build structures ­ preliminary conditions are defined in macrodefinitions, the initial values ­ the starting time and sampling step are inserted in the begining of input data. That algorithm have been used for pH monitoring in the medicine. Functioning of the algorithm have been tested on particular environment(under PC DOS). The testing takes care to provide dependence of measure step and timing characteristics of previously defined output data structures. Protocols have been received in text and graphic formats.

 

Autowave Recover of Contours

O. Zhelezov

Key Words: Autowave process; recover of images.

Abstract.. The report offers algorithm, that gives a possibility to recover the contours in images, using autowave process. A relation is shown between a form of wave front from a point source and the orientation of segments, into witch the recover will be made, using suggested algorithm. For rectangular diskreet elements this orientation is 00, 450, 900 and 1350. That’s means, that the suggested algorithm has a selectivity, witch is in relation to the form of wave front from a point source.

 

An Approach for Psycho-physiological Diagnostics of the Operator via his Speech

V. Gulabov

Key Words: Speech analysis; psychophysiology; psychoacoustics; man-machine system.

Abstract. The functioning of various systems often depends on the relevant actions of the operator, on the psychological characteristics of his interaction with people and technique. Faults and undue reactions leave heavy consequences. The basic means for the improvement of the man-machine system reliability is the incessant diagnostics of the man-operator state and consider the development of new noninvasive methods for indirect investigation of the psycho-physiological condition of the operator via analysis of his speech.

 

Computer Modeling of Track Circuits

N. Nedelchev

Key Words: Railway signalling; track circuit; computer modelling; sensitivity.

Abstract. The presentation of the rail line by the railway two-port network coefficients is considered in this paper. The analytical method for the determination of the long electrical line coefficients considering the earth is discussed. A numerical method is suggested. The method is applied to the normal mode, shunt mode and broken rail mode of operation. Some of the most important results are given, and the possibility of application of the method to each kind of track circuit is considered.