AVTOMATICA & INFORMATICA

 
 

2000

 

1

2-3

4

5-6

1/2000

Invariant Symbol Recognition Features Extraction about Size and Thickness

A. Popova, D. Mishev

Key Words: Handwritten isolated symbol recognition; self-learning neural network; symbol thickness normalization; tree structure searching optimization.

Abstract. The paper discusses a new approach for symbol thickness and size normalization, algorithm and program for processing and handwritten symbol recognition using self-organizing neural network. During scaling it takes place automatically additional symbols thickening and thinning. Aiming to increase the speed of recognition an optimization tree structure method of "winner" searching between neural network nodes is developed.

 

Non Integer Order Disturbances Absorbing Systems

E. Nikolov

Key Words: Robast control; disturbances absorbing; non integer differentiation; vertical largest size on U-contour; robast analysis; non integer order disturbance absorbing systems.

Abstract. The novelty in this working is the suggested class of astatic control systems under uncertainty. The article proposes: DASCRONE structure; DASCRONE synthesis algorithm; analysis of the convergence of the synthesis algorithm; wave disturbances classification; robast analysis and demonstration of DASCRONE robast stability and performance; DASCRONE estimation in comparative analysis by a parallel simulation of different control systems at identical conditions. DASCRONE synthesis is based on the wave disturbances absorbing principle; non integer differentiation; parametric and structure independence of the stability margin; vertical largest size criterion on U-contour and frequency correction method using wave models and disturbed characteristic models of the uncertainty. The applying of the disturbances absorbing principle extends the possibilities for the independent vertical largest size designing, increases the robast margin in comparison with DAS and CRONE-systems, guarantees an astatatism of the system in the integer multitude of the uncertainty.

 

Adaptive Smoothing Contours Method

O. Zhelezov

Key Words: Smoothing, adaptive filter.

Abstract. The report offers one method, that gives the possibility to smooth the contour lines in rastered contour images. The method uses the following of contour lines, that gives as the result the parametrical functions, that described the contour lines. The LF digital filter is used for linear transformation of contour functions. The adaptive change of filter's parameters gives the possibility to receive the contour, that have a given maximal distance between it and the given contour.

 

The Potentialities of the Method "Scanning Area" in Problems with Restricted Area

N. Nikolov

Key Words: Placement of objects; optimization.

Abstract. The method "scanning area" is used in optimizing the placement of interconnected objects. In the paper presented, the potentialities of the method for obtaining exact solutions in problems with restricted area are investigated. Such problems could be formulated beforehand or be solved, using high productive computing systems. On experiments with 12 elements the probability for obtaining exact solution from the optimization of a random one is 60%. The potentialities of the method for the real problems are above the limit of 12 elements.

2-3/2000

The Trends of network technology

O. Martikainen K. Boyanov

Abstract. . In the paper are present the future development of telecom sservices. The global telecom investments and telecom services in Europe are discussed. The penetration of Internet applications in Europe is considered as important tool for technology transfer. Three waves of service development are described as well as traffic based on TCP/IP The new service Platform Networks applications and new service management are treated too. Major trends in technology as they affect new ways of working and doing business and its links with progress in Europe's information society are described. The role of a new tool for academy cooperation is briefly treated.

 

Information Opposition ≠ Possibilities and Risk Estimation

E. Radev, S. Ohrimenko, G. Cherney

Key Words: : Information terrorism; hacker; computer crime; threat to information.

Abstract. . Information opposition is considered as an activity, aiming at obtaining of information superiority by destroying information in the enemy's computer system and at the same time ensuring the safety of one's own information system. A method for estimation of the created threat to information destroying is suggested.

 

Main Design Problems of Intelligent Systems for Training in Dynamic Systems

I. Zhelyazkova, G. Georgiev

Key Words: Inteligent systems for modeling and simulation; dynamic systems; knowledge representation; task presentation strategy; teaching strategy.

Abstract. An overview has been made of the contemporary status of problems pertaining to the design of intelligent systems for training in dynamic systems. They are described in the following order: modelling and simulation of dynamic systems, architectures of intelligent systems for training in dynamic systems, user interface, management and representation of subject area knowledge, task accomplishment strategies, teaching strategies, modelling and evaluation of trainee's knowledge. The conclusions at the end of the paper outline the tendencies in the above listed key problems.

 

Inspired from Immunology Behaviour Arbitration Mechanism for an Autonomous Mobile Robot

D. Tsankova

Key Words: Behaviour arbitration mechanism; immune network; genetic algorithm; autonomous mobile robot.

Abstract. This paper deals with a decentralized behaviour arbitration mechanism inspired from Immunology. The autonomous mobile robot navigation is realized by this approach. Two variants of the arbitration mechanism are proposed: the first of them uses heuristic immune network, and the second one - immune network tuned by genetic algorithm. The second variant is a trial to automatic constructing a suitable immune network for adequate action selection.

 

One Possibility for Practical Application of Cartesian Product

D. Budakova

Key Words: Cartesian product; relational model; MS Access uery subsystem; query; Structured Query Language.

Abstract. The paper deals with a type of problems in which solving, the application of Cartesian Product is relevant. It treats a method for solving such problems by finding a subset of Cartesian Product, that can be described and performed with a Query through MS Access tools. An example is given which is solely realized by the MS Access Query subsystem tools.

 

Using of an Mobile Robot for Exploration of Environments Comprising Unknown Objects

O. Manolov, S. Noikov, G. Georgiev

Key Words: Mobile robot; robot sensors; ultrasonic range finder; environment map.

Abstract. In the paper an algorithm of a mobile robot guidance for exploration of the environment is described. The vehicle is equipped with a rotating ultrasonic range sensor. Ultrasonic sensors are known as robust and cheap distance sensors suitable for this application. The data collected by range finder from any fixed point are limited by physical properties of ultrasound waves. Only those parts of surfaces are detected for which the impact wave direction appers to right angles. Therefore the sensor data from different positions must be combined to obtain complete representation of the environment.

4 - 2000

Procedural Dataflow Control of the Computations in Distributed Systems

B. Bonchev, V. Georgiev, K. Boyanov

Key Words: Distributed computing, dataflow control, load balancing, granularity, performance evaluation.

Abstract. The paper presents a hybrid model and architecture for distributed information processing. The model applies dataflow control principles on procedural level aiming to reduce the communication and synchronisation delays generated by the existing dataflow models on instruction level. The main characteristics of the model are parallel interpretation of the procedural code, application of complex machine operations and dataflow networks of nodes for multiple tokens. Performance results prove the linearity and extendibility of proposed architecture for distributed processing.

 

Evolution of Subroutine Concept in Procedure-based Programming (C/C++, Pascal, Java)

S. Bonev

Key Words: Programming languages; subroutines; functions; procedures.

Abstract. The article covers a survey on the subroutine concept applied to procedure-based programming. Different kinds of subroutines (procedures, functions, methods, co-routines) are under discussion. The evolution of the subroutine idea developed in contemporary programming languages from user point of view is being presented: overloaded routines, virtual functions and overriding methods, default-arguments routines, template routines.

 

Simulation Model for Evaluation of Robotized Complexí Operation

D. Tchakarski

Key Words: Simulation; simulation model; robotized complexes.

Abstract. . The task of the work is a simulation model for evaluation of the operation of robotized complexes (RC). Robotized complexes are complex production systems. Simulation modeling allows to disclose random factors, having in mind their effect on the operation of the automatic complex. Limits are ste to the conditions of the structural units of the RC. Markovís chains and Petriís nets are used to develop the simulation model. Different situations for serving of RC are input. The simulation model is realized as a program system IMAK for simulation and animation of the operation of RC and is implemented in production.

 

The Őodeling of robotized technological process of assembly

J. Zurek, P. Knast

Key Words: Modeling; assembly; Petri net.

Abstract. The paper concerns the modelling of technological processes of assembly. The aim of the paper is developing the methodology of modelling in case of technological processes of assembly. The aim of the paper is developing the methodology of modelling in case of technological processes of assembly. The principle of constructing models of technological processes of assembly are presented. A diagram was prepared describing the accuracy of the modelling process. Design procedures in accordance with the scheme ensure good elaboration of the model of technological process of assembly. The paper contains moreover the example of the modelling of robotized technological processes of assembly using Petri net. This methodology resulted in the preparation of computer software which aids the evaluation of technological processes of assembly.

 

A Controler for the Movements and Technological Operations of Coor-dinating Digital Control rogrammes

K. Kralev, K. Kristev

Key Words: CNC; personal computer; servoloop.

Abstract. In this paper a controler ensuring the movements and technology realization of decentralized digital-programming control is represented. The basic functions and structural sheme of the controler are given. The peculiarities of the program and control realization are characterized. The experimental results obtained clearing the controler turning are represented.

5-6 2000

Software Systems and Architectures

I. Plachkov

Key Words: Software architecture; architecture style; component.

Abstract. The paper presents a survey of the software architectures and styles in the software systems. The software architecture concepts and definitions are given. The general architecture styles and their properties are presented.

 

Replications in Distributed ORACLE Database System with Hierarchical Data Structure

V. Mitev

Key Words: Client-server model; Oracle server; distributed database systems; replication.

Abstract. Basic replication (read-only and updateable snapshots), the standard Oracle distributed functionality, is not suitable for database systems with hierarchical data structure and special data-access requirements. This article describes a distributed database structure with two information flows ≠ read-only standard data (up-down) and updateable operating data (down-up). There are special data-access privileges on these information flows defined. A particular method for separate replication schemas is presented, that satisfies the security requirements.

 

A A Programming Language for Modeling Animation Knowledge, Based on Didactic Petri Nets

I. Zheliazkova, S. Stefanova

Key Words: : Knowledge; modelling; dynamic systems; programming language; animation; Didactic Petri Nets.

Abstract. In computerised teaching animation is used to demonstrate dynamic system behaviour. In case of discrete event-driven dynamic systems (for example, communication, computer, dialogue, manufacturing, etc.), animation becomes so complicated that it can not express their important features such as parallelism, synchronisation and sharing of resources. To model the knowledge for animation of dynamic systems the authors propose a new extension of Petri Nets, called Didactic Petri Nets. The formal description of Didactic Petri Nets, syntax and semantics of the developed language, based on these nets are discussed in this paper. The general structure of teacherís program in this language and an example teacherís program also are presented.

 

Fractional Stochastic Extrapolations

N. Madjarov, M. Stefanov

Key Words: Stochastic extrapolator; fractional extrapolation; discreet Kalman filter.

Abstract. In this paper is described a stochastic extrapolator with fractional extrapolation step. The extrapolator gives maximum accuracy of the plant state vector estimate under the real restriction in the control system physical (practical) realization. Some test results are given (supplied) for checking the algorithm on plant models with different levels of complexity.

 

Control of Non-linear System, Described by Lorenzís Model

R. Radev

Key Words: Chaos; system; control; observer; feed back.

Abstract. This article deals with the problem of control of the classical Lorenzís system that illustrates chaotic movement. The synthesis of observer and feedback approach has been used on the base of the linearized model. The results show convergence of the processes in the closed system. The mode of these processes strongly depends on the initial conditions. At the same time, a lot of questions concerning the quality evaluation arise.

 

Robust Stabilised Control System

N. Nikolova

Key Words: Classical feedback loop; robust systems; parametric compensated system.

Abstract. This paper presents a method for design of robust control systems with internal model. Four systems of this type with different value of filter time constant are compared. The dynamic errors of these systems are estimated and a comparison with the classical feedback loop is done.

 

Multithreads Library for UNIX

L. Nikolov

Key Words: Process; threads; concurrency; operating systems; C/C++.

Abstract. The paper presents a user-level threads library that supports concurrent execution of threads within a single user process, running under UNIX system (SunOS). The processor time slices of the process are shared between its threads according to RR algorithm. The user can also choose a non-preemptive thread scheduling. The library is realized in C and provides calls, which can be used for various purposes as multitasking, simulation, experimentation with parallel programming. The features, the implementation and the use of the library are described.

 

Computer-Based Control of an Electrical Drive System

E. Kuzmanov

Key Words: Electrical drive system; improving; stand of testing; interface module; control program.

Abstract. The existing circuits for control of electrical drive systems (for example relay-contact) often limit posibilities of productivity and quality of the production. In this paper a computer-based approach is proposed to improve the electrical drive system of a stand for testing of stopping mechanisms. The existing control is replaced by computer-based. It is oriented to heavy-trucks and agricultural machines. For this purpose an interface module and a control program are designed.

 

Automatic Speech Segmentation in High Noise Condition

R. Ivanov

Key Words: Speech Segmentation; end points detection; voice activity detection.

Abstract. The accurate segmentation of speech and end points detection in adverse condition is very important for building robust automatic speech recognition (ASR) systems. Segmentation of speech is not a trivial process ≠ in high noise conditions is very difficult to determining weak fricatives and nasals at end of words. An efficient, threshold (a priory defined) independent speech segmentation algorithm, robust to level of disturbance signals is developed. The results show a significant improvement of robustness of proposed algorithm with respect to traditional algorithms.

 

Simulation Model for Diffuse Infrared Channel

G. Spassov

Key Words: Wireless LAN; diffuse Infrared channel; computer simulation; modulation technics.

Abstract. In this paper a controler ensuring the movements and technology realization of decentralized digital-programming control is represented. The basic functions and structural sheme of the controler are given. The peculiarities of the program and control realization are characterized. The experimental results obtained clearing the controler turning are represented.