## automaticaM. Hadjiski, N. Deliiski, P. Vitchev, D. Angelski, N. Tumbarkova. Computation of Average Moisture Content in Batches of Wood Materials during Thermal Treatment

Key Words: Wood materials; average moisture content; autoclave steaming; 2D mathematical models; Table Curve 2D; veneer production.

Abstract. A method and an algorithm for computing the average moisture content of the whole quantity of wood materials in given batch subjected to thermal treatment has been suggested. This value of the average wood moisture content is needed for calculation and automatic realization of optimal energy saving regimes for such treatment of the materials. The method is based on the use of two own mathematical models: one of the 2D temperature distributions in non-frozen prismatic wood materials during their thermal treatment and another – of the heat balance of steaming autoclaves. For numerical solving of the models and practical application of the suggested method, a software program was prepared in the calculation environment of Visual FORTRAN Professional developed by Microsoft and operating under Windows. Using this program computation of the non-stationary change in the processing medium temperature in an autoclave during steaming in it of non-frozen beech prisms with different moisture content aimed at their plasticizing before cutting them into veneer have been carried out. The variables used during the simulations were equal, as follows: an initial wood temperature of 0 °C, moisture content u from 0.4 to 0.8 kg·kg−1 with an interval of 0.05 kg·kg−1, and cross-section dimensions of prisms 0.4 × 0.4 m; steaming autoclave with inner diameter of 2.4 m, length of its cylindrical part of 9.0 m, and loading level with prisms of 50%; limited heat power of 500 kW of the generator, which feeds the autoclave with saturated water steam. The calculated by the models increase of the steaming medium temperature in the beginning stage of basic regime at u = 0.6 kg·kg−1 is compared with the real increase of that temperature at different values of u, which is periodically measured with a sensor in the automatic control system. After proper processing of the obtained differences between measured and calculated temperatures with the software package Table Curve 2D, an equation for calculating the average moisture content of the wood materials in the whole batch loaded in an autoclave is derived. The good accuracy of the suggested method is proved for the cases of autoclave steaming of non-frozen beech prisms intended for production of veneer.

## automaticaN. Petkov. How Process Control Systems Development Supports Digital Transformation

Key Words: Digital transformation; digitalization; process industries; process automation; simulation.

Abstract. The remarkable evolution of technologies in the last decade enables producers of automaton products, software, and systems to goes further in their solutions. At the same time process industries are challenged by the continuously changing competitive environment, keeping new health and safety regulations, and developing environmental-friendly products. New business models are created, and producers need to fit to be successful in their markets. Digital transformation (DT) is the way how process industries could go further. Process automation systems takes significant part in that transformation using the latest developed technologies. Different studies and research in the automation control theory, especially in the last decades, provides us the available knowledge base for further technology improvement. Normally there is a timeline gap between the theory and the practice due to the complex mathematical models and algorithms which were difficult and expensive to be executed in a real production process. With the development of the new automation hardware, software technologies and edge devices, driven by Industry 4.0, the implementation of theory is more applicable, and the return of investment is more visible. Nowadays, the development of science and production processes go more and more hand in hand from the stage of conceptual design the products production. The leading role has the rapid development of artificial intelligence, supported by the availability of new computer technologies, computational algorithms, and programming languages. The aim of this paper is to show a difference in digital transformation of discrete and process industries. The focus is the DT of process automation using parallel examples from the automation control theory and currently available software and hardware solutions.

## automaticaM. Hadjiski. 30th Anniversary Symposium on Control of Energy, Industrial and Environmental Systems

Key Words: Control praxis; ecology; energy; engineering; industrial automation; innovation.

Abstract. The presented overview represents a general view of the successfully held 30th edition of the International Symposium on Control of Energy, Industrial and Environmental Systems. This was not a narrowly specialized forum, it was a search for a possible way to build a bridge between theoretical achievements and their practical implementation in industrial automation. The main automation engineering companies and the relevant organizational structures in industry and business in Bulgaria have invariably been active participants and sponsors of the symposium. The total number of reports and company presentations published in the pro- ceedings of the symposium exceeded 500. During the three decades of its existence the symposium was constantly evolving following the rapid progress of theoretical achievements, new technical devices and advanced software, emerging innovative technologies based on Big Data and Artificial Intelligence. The symposium was a place for productive discussions, exchange of experience and mutual enrichment of specialists with different profiles. It was a suitable environment for creating new contacts, which in many cases grew into long-term business cooperation. The symposium was a forum for popularizing the scientific and practical achievements of industrial automation in Bulgaria. It was often a place for first appearance and publication of young specialists from scientific circles and industry.

## automaticaM. Hadjiski. Integration of Decision Making and Control Systems

Key Words: Artificial intelligence; control systems; data-drivenprocess; Decision Making; human-machine interaction; optimization.

Abstract. The work examines the main aspects of the integration of decision making (DM) processes and the control of systems (Control Systems, CS) in modern objects with great complexity and complexity from the perspective of effective application of artificial intelligence methods using data flow. The DM procedure is treated in the light of modern settings and requirements for successful functioning under difficult to overcome conditions such as great uncertainty, scarcity and low quality of data, multicriteria, stochasticity, significant limitations, variability of structures and parameters. Particular attention is paid to the need to increasingly involve machine methods in hybrid Decision Making (DM). The solution of the DM task is treated as an optimization problem that can be solved by different formal, heuristic and hybrid methods depending on the context, existing experience and knowledge, available resources – cost, time, qualification. Special attention is paid to DM and CS approaches in centralized, decentralized and distributed site structures. The wide range of possibilities for the application of technologies based on artificial intelligence and the perspective of their application are indicated.

## automaticaN. Deliiski, D. Angelski, P. Vitchev, N. Tumbarkova. Computation of Energy Consumption and Efficiency of Autoclaves during Steaming of Wooden Prisms by Regimes with Dispatching Intervention in them

Кey Words: Non-frozen wooden prisms; unsteady models; autoclave steaming; energy consumption; energy efficiency; dispatching interference; veneer production.

Abstract. An approach for computing the energy consumption and energy efficiency of autoclaves for intensive steaming of non-frozen wooden prisms at limited heat power of the steam generator in cases of dispatching intervention into the temperature-time parameters of steaming regimes in order to obtain a duration that is suitable for the subsequent cutting of the veneer from the heated plasticized prisms has been presented. The approach is based on the use of two personal mathematical models: 2D non-linear model of the unsteady distribution of the temperature in the cross-section of non-frozen prismatic wood materials subjected to heating at conductive boundary conditions and consequent conditioning in an air environment, and model of the non-stationary thermal balance of autoclaves for steaming wood materials. For numerical solving of the models and practical application of the suggested approach, a software package was prepared in the calculation environment of Visual FORTRAN Professional developed by Microsoft and operating under Windows. Using this package computations and research of the change in the energy consumption and energy efficiency of steaming autoclaves for plasticizing of non-frozen beech prisms before cutting them into veneer have been carried out. The variables used during the simulations were equal, as follows: an initial wood temperature of 0 °C, moisture content of 0.6 kg·kg−1, and cross-section dimensions of the beech prisms 0.4 × 0.4 m; steaming autoclave with inner diameter of 2.4 m, length of its cylindrical part of 9.0 m, and loading level with prisms of 50%; limited heat power of 500 kW of the generator, which feeds the autoclave with saturated water steam. The calculations were carried out for the cases of reducing by the dispatcher the maximum temperature of the basic steaming regime from 130 °C to 120, 110, and 100 °C in the 3rd , 7th , and 11th hour of this regime. The suggested approach can be applied for creation of software for systems used for computing and model-based automatic realization of energy-efficient regimes for autoclave steaming of non-frozen wood materials with desired duration set by the dispatcher.

## automaticaV. Ruykova. Generalized Predictive Control with Disturbance Compensation for Time-delay Processes

Key Words: Generalized predictive controller; disturbance compensation; time-delay; Diophantine equation.

Abstract. The aim of this paper is to design predictive algorithm for control of time-delayed systems with the possibility of measurable disturbance compensation. A new approach to extended Generalized Predictive Control (GPC) has been proposed. Three Diophantine equations are solved non recursively. The cost function and the control law of the GPC are derived. Simulation examples are presented to show results of the design. Two cases are considered – in case of delay between the input and the output of the process, less than the delay, between the disturbance and the output of the process, and in case of delay between the input and the output of the process, greater than the delay between the disturbance and the output of the process. In both cases, comparisons were made between a standard GPC, a compensator with future interference values included in the GPC, a compensator without future interference values included in the GPC and a classic compensator for one case. The results show that the GPC cannot completely eliminate the disturbances, even when the future disturbances values are included in the control. Complete elimination of the disturbances is possible only when the weighting factor, that distributes the energy of the controller, is zero.

## automaticaM. Petrov. Multiple Objective Optimisation for the Ethanol Production from Strain Saccharomyces sereviciae

Key Words: Multiple objective optimisation; ethanol production; Saccharomyces sereviciae; general multiple objective optimisation; fuzzy optimisation; fuzzy multiple-objective optimisation.

Abstract. A fuzzy procedure is applied in order to find the optimal feed policy of a fed-batch fermentation process for ethanol production using a Saccharomyces serevicieae. The policy consists in feed flow rate, feed concentration, and fermentation time. In this study biotechnological process is formulated as a general multiple objective optimisation problem. By using an assigned membership function for each of the objectives, the general multiple objective optimisation problem can be converted into a maximizing decision problem. In order to obtain a global solution, a method of fuzzy sets theory is introduced to solve the maximizing decision problem. After this multiple optimisation, the useful product quality is raised and the residual substrate concentration is decreased at the end of the process. Thus, the process productiveness is increased.

## automaticaM. Hadjiski. Мutual Penetration and Enrichment as a Bilateral Accelerating Factor for the Development of Machine Learning and Automation

Key Words: Artificial intelligence; control theory; deep learning; industrial automation; machine learning; reinforcement learning.

Abstract. The study shows that the existence of fundamental similarities between control theory and machine learning is a real basis for productive interpenetration and enrichment with new concepts, methods and tools, which are mutually beneficial for overcoming a number of serious modern challenges such as the control of complex and autonomous systems, cybersecurity, intelligent robotics, bioautomatics. The continuous development of the control theory as a result of its own progress and under the influence of the ideas of artificial intelligence will not allow the transformation of automation into a routine engineering discipline. In turn, the systems based on artificial intelligence and machine learning are enriched with well-developed methods and procedures from the control theory in order to improve and create new algorithms and to ensure a higher speed, robust stability and optimality of the learning process. Industrial automation systems will absorb the innovative results of the interpenetrating development of artificial intelligence and control theory improving both the quality and scope, safety and security of operations.

## automaticaN. Deliiski, D. Angelski. Computation of the Processing Medium Temperature during Autoclave Steaming of Non-frozen Wooden Prisms

Кey Words: Wooden prisms; veneer production; autoclave steaming; 2D model; processing medium temperature; energy consumption; heat balance; loading level of autoclave; moisture content of prisms.

Abstract. A methodology for computation of the processing medium temperature and connected with it energy consumption and heat fluxes during autoclave steaming of non-frozen ooden prisms for veneer production at limited heat power of the steam generator, depending on the dimensions of the prisms cross section, wood moisture content, and loading level of the autoclave has been suggested.
The methodology is based on the use of two personal mathematical models: 2D non-linear model of the temperature distribution in subjected to steaming non-frozen prismatic wood materials and model of the non-stationary heat balance of autoclaves for steaming wood materials. The heat balance of the autoclaves consist of following components: energy used for heating of the subjected to teaming wood materials, energy used for heating of the body of the autoclave and of the situated in it metal trolleys for positioning of the wood materials, energy used for heating of the insulating layer of the autoclave, energy used for covering of the heat emission from the autoclave in the surrounding air, energy used for filling in with steam the free (unoccupied by wood materials) part of the working volume of the autoclave and energy, which is accumulated in the gathered in the lower part of the autoclave condense water. For numerical solving of the models and practical application of the suggested methodology, a software package was prepared in the calculation environment of Visual FORTRAN Professional developed by Microsoft. Using this package computations and research of the non-stationary change of the processing medium temperature in an autoclave with a diameter of 2.4 m, length of its cylindrical part of 9.0 m and loading level of 40, 50, and 60% at a limited heat power of the steam generator, equal to 500 kW during the initial part of the steaming process in it of beech prisms with cross-section dimensions of 0.3 × 0.3 m, 0.4 × 0.4 m, and 0.5 × 0.5 m, initial temperature of 0 °C, basic density of 560 kg·m-3, moisture content of 0.4, 0.6, and 0.8 kg·kg-1 have been carried out. Simultaneously with this the heat fluxes and energy consumption required for the heating of the prisms and for the whole steaming process in the autoclave have been calculated. The suggested methodology can be used for the computation and model based automatic realization of energy efficient optimized regimes for autoclave steaming of different wood materials

## automaticaM. Hadjiski. Cyber Security of Industrial Control Systems

Key Words: Advanced control; cyber security; industrial control system; networked control; resilience; simulation.

Abstract. An overview of the problems, research efforts and recent results on cyber security of Industrial Control Systems is provided. The interaction between the basic control sub-systemsthe advanced control of the plant, the system for predictive safety maintenance and the cyber-security control system is considered. In the paper is shown that cyber security should be treated as a holistic problem and could be successfully solved if tight integration of technological, organizational and human aspects will be achieved. Several approaches for design of contra-actions via implementation simulation and Artificial Intelligence-based technologies are analyzed. Some problems of attack-resilient control of Industrial Control Systems are discussed.

## automaticaS. Yordanov, G. Mihalev. System for Automatic Reporting a Labour Productivity in Real Time Based on ESP32 Controller

Key Words: Internet of Things (IoT); Wi-Fi module ESP32; Arduino IDE development environment; LPWAN technologies; electronic accounting technologies.

Abstract. In this paper, an ESP32 application in implementing systems for automated reporting of the utilization rate of production capacities in real time is considered. A technical solution of remote control and monitoring of the production process in a textile company, through a dedicated module for sending the time spent on a remote server via Wi-Fi, Lan or Bluetooth is proposed. The obtained information is used to control the production process in real time and determination of the remuneration of workers.

## automaticaV. Boishina. Situattion Predictive Control for Energetic Systems

Key Words: Distributed diagnosis; supervisor control; case base reasoning; predictive control.

Abstract. The research is mainly focused of using of possibility to collect the historical information about the behavior of the control system. The main focus is to illustrate using of the Case Base Predictive Control, which optimizes the way of choosing the optimal way of control of the system in respect of taking the decisions according to the historical experience about system behavior and fast changing outdoor parameters. The paper described forming of cases which describing different system situations and the appropriate way of choosing of the right way of system control. The proposed research represented the possibility to aplly Case Base Reasoning (CBR), based on the previous knowledge about system behavior and possible system disturbances caused from different environment changes (climatic and economic ones). The research propose the way of optimizing the control of energetic control system based on previous known cases.

## automaticaM. 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.

## automaticaV. 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.

## automaticaN. 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.

## automaticaA. 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.

## automaticaM. Hadjiski. Does Automation Become a Routine Engineering Discipline

Key Words: Artificial intelligence; automation; control theory; knowledge.

Abstract. During the second half of the twentieth century Automation was doubtlessly one of the most dominant scientific and engineering directions. In control theory a number of original concepts with a fundamental importance received a quick and deep development – dynamic systems, feedback, stability, modeling, identification, optimization, robustness, controllability and observability. These new concepts rendered a strong interdisciplinary paradigmal impact on a variety of scientific areas of advanced activities – computer science, decision making as well as on classic sciences like neuroscience, psychology, medicine, economics, education and many others. On the other hand contemporary Automation absorbs in a natural way lots of relevant achievements in other scientific directions like the fuzzy logic, the approximation theory, the neural nets, the network approach, learning, elements of the artificial intelligence, etc. But during the last fifteen years there was an obvious decrease of the verbal attendance of the Automation problematics in societal debates about the emerging challenges in a globalizing world. In the present paper it is argued that Automation continues to be a solid reactive and proactive factor in the formation of the societal strategy and in the running advanced technological and scientific policy because: (i) Automation speeds up its internal advanced development solving new emerging problems, (ii) Automation possesses relevant tools to predict corresponding scientific challenges and to Overcome Them, (Iii) Automation Will Be Together With Artificial Intelligence The Most Powerful Action In The Social Digitalization In The Near Future.

## automaticaG. Mihalev, H. Stoycheva. Synthesis of a Linear Quadratic Controller for Vibratory Bowl Feeder

Key Words: Vibratory bowl feeder; LQR controller; robust analysis.

Abstract. In this paper, a synthesis of the LQR control unit for a vibratory feeding and orientation module is presented. The device representing the control object is considered as a two-mass resonating system. In the presence of parametric uncertainty, a linear model of the system in state space is produced. A robust closed-loop analysis has been accomplished, showing the robust quality and robust stability of the system provided by the LQR controller.

## automaticaE. Mihailov, K. Boshnakov, I. Petrova. Risk Assessment of Liguid Steel Breakout in Metallurgical Ladle

Key Words: Risk assessment; liquid steel breakout; metallurgical ladle; infrared thermography.

Abstract. In the present paper is considered the risk assessment for liquid steel breakouts from metallurgical ladle. The damages with different form are investigated. Mathematical models for geometric dimensions of damages and temperature field on metallurgical ladle are created. The temperature field is measured by infrared thermo camera.

## automaticaN. Deliiski, D. Angelski, N. Trichkov, Z. Gochev. Computation of the Average Mass Temperature of Wood Details during their One Sided Heating

Кey Words: Average mass temperature; oak details; one sided heating; plasticizing; bending.

Abstract. An approach for computing the average mass temperature of the wood and the rate of its change during one sided heating of flat wood details, has been suggested. The approach is based on the use of the solutions of own non-linear model for the calculation of the non-stationary 1D temperature distribution along the thickness of subjected to one sided conductive heating flat wood details aimed at their plasticizing in the production of curved back parts of chairs. A software program has been prepared in the calculation environment of Visual FORTRAN Professional for solving of the model. With the help of the program, the 1D non-stationary temperature field in flat oak details with an initial temperature of 20 oC, moisture content of 0.15 kg.kg-1, thickness of 12 mm, 16 mm, and 20 mm during their 30 min one sided heating at temperature of 80 oC and 120 oC of the heating metal body has been calculated. After integration of the temperature field, the average mass wood temperature and the rate of its change of the subjected to one sided heating oak details has been calculated. The obtained results are graphically presented and analyzed.