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V. 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.

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M. 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.

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M. 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.

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N. 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

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M. 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.

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S. 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.

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V. 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.

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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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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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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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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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M. 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.

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G. 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.

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E. 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.

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N. 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.

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R. Vladova, E. Kirilova, N. Vaklieva-Bancheva. Method for Overcoming Uncertainties and Increasing Resilience through Heat Integration of Flows in Batch Production Systems

Key Words: Heat integration; batch processes; stochastic optimization; flexibility index.

Abstract. By definition, sustainable development is a way of using natural resources that aims to meet human needs while maintaining the natural balance with the environment, so that these needs can be met both now and for future generations. The creation of highly efficient technological processes, energy efficiency in every sphere of the economy and society, the production of energy from renewable energy sources, the economy of materials, the use of renewable natural resources, the development of green and eco-technologies, prevention of harmful waste; effective governance of the economy, society and the environment are part of the most important policies underlying the European Union’s (EU) Sustainable Development Strategy. Creating energy efficient production systems involves less impact on the environment. One of the most powerful tools for creating this type of system is the integration of energy and mass processes. Process integration covers a wide range of system-oriented methods and approaches that are used in the design and reconstruction of industrial processes to obtain optimal use of resources. In recent years, the focus on energy integration of processes has shifted from the integration of processes in continuous systems to the integration in systems with batch processes. From the conducted researches it is clear that the production systems with batch processes have sufficient energy potential, which can be used to improve their energy efficiency. The recovery and use of this heat is complicated by the batch nature of the processes, and the task is further complicated by the impact of stochastically changing flow parameters such as temperature, volume, etc., overcoming which is a serious challenge to the sustainability of batch production systems. The aim of the present study is to propose a method for dealing with uncertainties and increasing resilience through heat integration of flows in periodic production systems. The method includes three main stages: 1. Uncertainty analysis and selection of a suitable scheme for energy integration of processes and its mathematical description; 2. Defining the problem of optimal redesign of an energy-integrated batch production system by incorporating the integration model within a stochastic optimization problem and its solution; 3. Assessment and decision making to choose the most appropriate solution, whereby the production system is sustainable of the impact of the uncertain parameters in the widest borders, by defining the flexibility index.

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M. Hadjiski, N. Deliiski. Intelligent Control of the Wood Thermal Treatment Process under Variable Scheduling. Part 2. Intelligent Control of the Operational Management

Кey Words: Case-Base Reasoning (CBR); mathematical modeling; operational conditions; scheduling; suboptimal control; Thermal Treatment Process (TTP).

Abstract. An intelligent system for control of the thermal treatment process (TTP) of wood materials addressed toward manufacturing with necessity of often rescheduling is proposed via combination of model-based and data-driven approaches. Using First-principle mathematical model of TTP presented by Partial Differential Equations in 2D space with suboptimal model-based control algorithm and Case-Based Reasoning (CBR) approach an explicit suboptimal control system is investigated in different operational conditions. A set of virtual subspaces for feasible operational situations for variety of objective criteria of value assessment is created using traditional problem-decision representation. As the search spaces are well structured, the search procedure based on traditional K–NN algorithm is strongly simplified. In this way the complicated computer simulation of the TTP at each time step due to the plant’s parameter distribution, nonlinearity and operational or environmental disturbances are fulfilled off-line. On-line are accomplished relatively small part of the calculations connected with the traditional R4–operations in CBR, objective functions estimation, some databased and rule-based control parameter corrections and possible adaptation from charge to charge. Some results of the simulation experiments are presented and analyzed.

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I. Petrov. Hierarchy of the Structure of Energy Balances

Key Words: Information theory; entropy; hierarchy; energy mix; renewable energies.

Abstract. The dynamics of development and distribution of resources are key questions for characterizing the complexity of systems in a large number of areas. Traditionally, the natural sciences (physics, chemistry, computer science, telecommunications, and others) have used Shannon’s information theory and the concept of entropy to assess diversity, uncertainty, and chaos. Social sciences (economics, competition law, etc.) prefer to consider these issues from the opposite point of view – the concentration of resources, reflecting the dominance and hierarchy in competition interactions. Energy systems are a typical example of complex and dynamic systems and their study is of particular interest in theoretical and practical terms. Becoming the engine of innovation in energy technologies, renewable energy sources play an important role in the evolution and dynamics of energy balances at the international, national and local levels. The article presents the possibilities of the original method developed by the author for estimating the hierarchy of information, its advantages in comparison with the traditional methods of Shannon’s entropy and Herfindahl concentration and its application for improving the analysis of energy balances and the role of renewable energy sources.

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Intelligent Control of the Wood Thermal Treatment Process under Variable Scheduling. Part 1. Problem Statement and Approaches

Кey Words: Case-Base Reasoning (CBR); mathematical modeling; operational conditions; scheduling; suboptimal control; Thermal Treatment Process (TTP).

Abstract. An intelligent system for control of the thermal treatment process (TTP) of wood materials addressed toward manufacturing with necessity of often rescheduling is proposed via combination of model-based and data-driven approaches. Using First-principle mathematical model of TTP presented by Partial Differential Equations in 2D space with suboptimal model-based control algorithm and Case-Based Reasoning (CBR) approach an explicit suboptimal control system is investigated in different operational conditions. A set of virtual subspaces for feasible operational situations for variety of objective criteria of value assessment is created using traditional problem-decision representation. As the search spaces are well structured, the search procedure based on traditional K–NN algorithm is strongly simplified. In this way the complicated computer simulation of the TTP at each time step due to the plant’s parameter distribution, nonlinearity and operational or environmental disturbances are fulfilled off-line. On-line are accomplished relatively small part of the calculations connected with the traditional R4–operations in CBR, objective functions estimation, some databased and rule-based control parameter corrections and possible adaptation from charge to charge. Some results of the simulation experiments are presented and analyzed.

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K. Boshnakov, D. Slavcheva, D. Petkova. Empirical MIMO Model of Biological Wastewater Treatment

Key Words: Empirical MIMO model; biological wastewater treatment; Wiener model structure; Principal Component Analysis; polynomial approximation; neural networks.

Abstract. The aim of the present work is to develop data based MIMO mathematical model for biological wastewater treatment, designed for real-time work, and a procedure for creating mathematical models of this class. An analysis of the processes of biological wastewater treatment for the purposes of their mathematical modelling is made. The study includes variables that are known to have sensors worldwide or to have software sensors developed. In conducting the research published in the present work, a combination of real and synthetic data is used. The constructive parameters of the considered installation correspond to settlements with an average number of equivalent inhabitants for the country. To develop a MIMO nonlinear dynamic mathematical model, the structure of Wiener model was chosen – series-connected linear dynamic and nonlinear static parts. The procedure for creating the mathematical model includes: processing of incoming data by the principal components method (PCA); to form the nonlinear static part of the model and to compare the predictive abilities, polynomial dependences for each of the intermediate and target variables are derived as a function of the normalized values of the three principal components and two types of neural networks for each variable are trained. In one case the independent variables are the normalized values of the principal components and in the other – the natural values of principal components. In some cases, higher accuracy of approximation is obtained in polynomial dependencies, in others in neural networks. In neural networks, the same approximation accuracy with polynomial models is obtained with a larger number of parameters. Based on simulation studies, the dynamic characteristics of an installation for biological wastewater treatment are derived. A block diagram of the mathematical model for is presented. The created mathematical model can be used on a modular basis with respect to the target variables of interest, regardless of the other target variables.

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