automatica
M. Hadjiski. Model-based ot Model-free Approach in Control

Key Words: Artificial intelligence; automatic control; data driven methods; machine learning; model-based control; model-free control.

Abstract. Classical model-free control methods, which still have extremely large application in industry are considered in historical perspective and in accordance with their advantages and disadvantages. Some of the most popular model-free approaches, adopted last three decades (ultra-local model-based, rule-based, express system-based) are treated tacking into account their pros and cons, depending on the complexity of the control problem and the business aspect. A special attention is paid to contemporary very actual data-driven approaches. The most promising of them, oriented to AI-based technologies (especially machine learning) are discussed. A comparative analysis is carried out in order to clarify the advantages, disadvantages and challenges of model-based and model-free approaches implementation in control in big data era.

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automatica
V. Hristov, S. Gramatikov, G. Georgiev, E. Genchev. Virtual Tool for Improvement of a Stand for the Study of the Characteristics of a Direct Current Motor

Key Words: DC motor; virtual instrument; LabVIEW; mechanical characteristics.

Abstract. This article is an enhancement of an existing bench by creating an instrumental tool through LabVIEW for automated mechanical characteristics removal of a DC motor on a system generator-motor. By using the Arduino microcontroller for analogue-to-digital conversion from the sensor (modules) and for connection to the computer, it allows with a relatively small amount of resources to upgrade an existing stand. Voltage dividers for voltage measurement and built-in virtual instrument and graphical screen for visualizing the system’s operation processes were built.

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automatica
N. Perchemliev, A. Grancharova, K. Boshnakov. Hierarchical Control System for Gas Condensate Stripping Installation in the Ammonia Production Process

Key Words: Ammonia production; gas condensate stripping; hierarchical control system; profit loop; supervisory control.

Abstract. In this paper examines an existing industrial plant for gas condensate stripping, which is part of ammonia production. Processes and apparatuses are described. Real industrial measurements were made on the basis of which analyses were made. A conceptual architecture of a hierarchical control system for installation’s control is presented. The suggested architecture can be implemented and tested with the existing Honeywell’s Experion PKS. The main purpose of the hierarchical control system is to improve the efficiency of heat sources and the quality of the stripped gas condensate. This will improve the economic performance of the entire ammonia plant.

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automatica
A. Pavlov, N. Nikolov, M. Alexandrova. PLC-Based Process Control System for Catalytic Vacuum Pyrolysis Installation of Waste Raw Materials

Key Words: Catalytic vacuum pyrolysis; state space; state observer; state controller; MATLAB Simulink; PLC; SISO; Unity Pro XL.

Abstract. This paper discusses problem designing PLC-based process control system for catalytic vacuum pyrolysis. Paper presented PLC-based discrete state modal controller for SISO systems. It is based on observer of Luenberger. The state controller is synthesized as a functional block in programming environment Unity Pro XL for PLC series Modicon M340 of Schneider Electric.

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informatics
V. Aleksieva, A. Hulian. Crypto-token Based on Smart-contract of Ethereum Blockchain

Key Words: Ethereum; block chain; smart contract; crypto-token; crypto-currency.

Abstract. The proposed paper realized a smart contract based on Ethereum blockchain. The decentralized crypto-token is created for Initial Coin Offering (ICO) and based on ERC20 standard. A web-based interface is created for sale of these crypto-tokens. The results from experimental tests are presented.

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achievements and applications
G. Georgieva-Tsaneva, M. Gospodinov, E. Gospodinova. Analysis of Heart Rate Variability through Statistical Parameters

Key Words: Heart Rate Variability; Statistical Analysis; Atrial Fibrillation; Premature Ventricular Contraction; Normal Sinus Rhythm; Orthogonal Transforms.

Abstract. Cardiovascular diseases are among the first causes of death. The main cardiovascular diseases are myocardial ischemia, various types of arrhythmias, reduced ability to contract the left ventricle. Cardiac testing is performed non-invasively by electrocardiograph or Holter monitoring. The paper examines, through the application of orthogonal transforms, the continuous holter recordings of individuals with Atrial Fibrillation, Premature Ventricular Contraction and Normal Sinus Rhythm. The mathematical analysis is performed in the time domain. The results show characteristic differences between patients with both types of arrhythmias and in healthy individuals. The presented results can be of benefit to cardiology practice in Bulgaria and worldwide.

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