Papers by Djordje Dihovicni
Communications - Scientific letters of the University of Zilina, 2011
This paper points to sufficient conditions for practical stability of linear systems with time de... more This paper points to sufficient conditions for practical stability of linear systems with time delay in state. Particularly, in control system engineering practice, despite the contribution to the contemporary control theory and system thinking, the problems of practical stability are not developed in details. Taking into account that the system can be stable in a classic way, but it can also possess inappropriate quality of dynamic behavior, and because of that, it is not applicable. For engineers it is crucial to take the system into consideration in relation to permitted states in phase space which are defined for such a problem, Dihovicni et al. (2006). Although, there are some papers covering practical stability problems, the lack of exploring it by using fundamental matrix and matrix measure was observed. Our main idea is to present definitions and conditions for practical stability, applying matrix measure approach. From a practical view point, it is crucial to find intervals on which the system is stable, and to know the function of initial state, the "prehistory" of system motion. The practical stability for a class of a distributed parameter system is also presented. The system is described in state space and a unique theory for such a problem is developed where a fundamental matrix of system and matrix measure is used. Using an efficient approach based on matrix measure and system fundamental matrix, the theorems for practical stability of distributed parameter systems are developed, and superiority of our results is illustrated with a numerical example.
Communications - Scientific letters of the University of Zilina, 2011
One of the most important tasks in the safety engineering lies in the construction of a knowledge... more One of the most important tasks in the safety engineering lies in the construction of a knowledge database of decision support for the chemical plants, and that way to ensure optimal conditions, improve quality and boost efficiency. Methods of analysis of control systems and simulation methods, which are used for observing dynamic behavior of linear systems with time delay, and distributed parameter systems, based on linear algebra, operation calculus, functional analysis, integral differential equations and linear matrix non-equations showed long ago that modern electronic components can be used to achieve more consistent quality at lower costs in safety engineering. The main idea to do so is that the quality service is maintained and controlled. Applying the Fuzzy theory in decision making has given very good results, and provided a flexible framework and over the years numerous mathematical models have been developed.
Transient in long pneumatic lines is analyzed from time delay and construction view of point. Aft... more Transient in long pneumatic lines is analyzed from time delay and construction view of point. After presented mathematical model of pneumatic system, there are shown stability issues, and it is calculated length of the pneumatic pipeline for which the system is stable. The paper's main contribution is the application of decision and fuzzy logic in determination the stability of long pipeline from construction perspective by using DB2 database approach, and proposal of possible applications of knowledge database and fuzzy logic in making diagnostics conclusions about the states of the safe operation and reliability of the system. ARTICLE HISTORY
Experimental and Computational Investigations in Engineering, 2020
In this paper the automation of cup filling machine by inserting PLC unit for educational purpose... more In this paper the automation of cup filling machine by inserting PLC unit for educational purpose is presented. Small filling machine has been constructed, and it has ability to recognize two cup sizes and sort them after filling. The machine charger works independently at 220 V, the sizes of the glasses it fills are 0.2 l and 0.1 l, and it has its own liquid tank with level sensor and compressor and bottle with pressure sensors and automatic on and off button. The conditions for starting the machine, are that the air pressure is above 2 bar, and the level of liquid in the vessel is sufficient to fill one whole glass after signaling the disappearance of liquid. The required width of the conveyor belt is 10 cm, and it is driven by a 12 V electric motor. The cups are sorted using a pneumatic piston, and the liquid circulation pump is of constant flow. In the operation of the machine, it is necessary to provide protection against incompletely filled cups due to liquid loss, and protection against incorrect sorting due to loss of air pressure, and light alarm in case of loss of conditions. The alteration of machine's control units is shown by replacing specific components with the programmable logic controller SIEMENS S7 300. A detailed description of the installation wiring and programming of PLC is described, as well as the program execution using PLC SIM software. The final phase involved program testing, and testing of particular system operations.
International Journal of Computational Intelligence Systems, 2013
The paper describes solving problem of constructing knowledge database of a decision making in pr... more The paper describes solving problem of constructing knowledge database of a decision making in process safety. It provides analyses of the requirements as well the analyses of the system incidents caused by specification, design and the implementation of the project. Main focus of this scientific paper is highlighted on practical stability problem and conditions for optimal performance of safe fault-tolerant controllers, I/O, engineering and pressure transmitters. Algorithm of decision making in process safety is developed and the system has been realized taking into account C# approach in Windows environment.
Modeling and Simulation in Engineering, Economics, and Management, 2013
For multivariable multi-delay systems which is represented by distillation column, is applied a f... more For multivariable multi-delay systems which is represented by distillation column, is applied a frequency- domain approach to an arbitrary finite spectrum assignment for time-delay systems. By this approach the unstable open-loop systems may be stabilized and therefore controlled by means of some well- established methods for time delay open-loop stable systems. It is proved that the control law achieves arbitrary finite spectrum assignment and is physically realizable.
Current Problems in Experimental and Computational Engineering, 2021
2017 13th International Conference on Advanced Technologies, Systems and Services in Telecommunications (TELSIKS), 2017
In this paper are presented the methods for security maintaining a web application. Beside fundam... more In this paper are presented the methods for security maintaining a web application. Beside fundamental aspects of security of ASP.NET application, also are presented the actions which are necessary to achieve required security, as well as security approach of the code in NET framework. It is shown the user authentication, windows verifying authenticity, and protection by using configuration file. The analysis of the definition of the rules of identification or authorization is maintained by means of tools of WAT, and then it is shown the manner in which displays a login page.
Applied Engineering Letters : Journal of Engineering and Applied Sciences, 2020
The model of e-commerce web store is developed and analyzed from supply chain management view of ... more The model of e-commerce web store is developed and analyzed from supply chain management view of point. Main focus of this scientific paper is highlighted on fuzzy approach to crucial data about products, stored in the database of e-commerce web shop. For unit price of the product, and the probability of buying product of certain dimensions, it is calculated the fuzzy mean of the expected prize and the variance. The SWARA method is implemented and relative weight criteria is calculated in order to optimize supply chain management.
Applied Engineering Letters : Journal of Engineering and Applied Sciences, 2019
In this paper it is presented how to create a part of a dynamic website that is used to filter da... more In this paper it is presented how to create a part of a dynamic website that is used to filter data and create a user basket for online purchase of machine products. It is explained how the ASP.Net Core 2.2 MVC technology works. The difference between code first and database first access is shown as well as are different ways to implement a database into a project. This project was built gradually starting from system setup, through the creation of a database that was customized to customer needs, until the layout itself, in which are used markup and styling languages such as HTML5 and CSS.
Applied Engineering Letters : Journal of Engineering and Applied Sciences, 2019
The main objective of this paper is to show the technology to protect computer systems using fire... more The main objective of this paper is to show the technology to protect computer systems using firewall technology and through the configuration of firewall, construct defence and protection of the database of the mechanical system engaged in the auto industry which create pipe for exhaust systems on cars by using various techniques, tools, methods, and testing of the software of the firewall and anti-virus. For security reasons, it is necessary to create a script file for anti-virus system and firewall, and rules in order to handle with the database when it is updated.
Applied Engineering Letters : Journal of Engineering and Applied Sciences, 2018
In this paper it is presented creation and encryption of e-commerce database for selling mechanic... more In this paper it is presented creation and encryption of e-commerce database for selling mechanical elements. It is shown a procedure of creation a database and tables with appropriate data, which is the first step in developing stable e-commerce application. For security reason it is necessary to encrypt the database, and it is described a complete process, and as well it is given part of the code of web application for inserting data into the tables, deleting some data and updating them. In developing ecommerce application for selling mechanical parts, it is applied C# programming language by using ASP.NET, with using HTML language and XML.
Lecture notes in business information processing, Jun 6, 2013
Transient in long pneumatic lines is considered from distributed parameter and as well time delay... more Transient in long pneumatic lines is considered from distributed parameter and as well time delay view of point, and are presented time responses. By using Simulink module of program Matlab, efficiency is simulated pneumatic system with time delay. It is proved that the control law achieves arbitrary finite spectrum assignment and is physically realizable.
The paper describes simulation of pneumatic cylinder systems with long pneumatic pipes. Problem i... more The paper describes simulation of pneumatic cylinder systems with long pneumatic pipes. Problem is considered from parameter distribution and time delay perspective. It is applied the control for special group of distributed parameter systems, with distributed control, where control depends of one space and one time coordinate, and finite spectrum assignment method is implemented for time delay system. The stability on finite space interval is analyzed and efficient program support is developed in symbolic Maple program language.
Computational Intelligence in Business and Economics, 2010
Advances in Computer Science and Engineering, 2011
Program support, simulation and the animation of dual action pneumatic actuators controlled with ... more Program support, simulation and the animation of dual action pneumatic actuators controlled with proportional spool valves are developed. Various factors are involved, such as time delay in the pneumatic lines, leakage between chambers, and air compressibility in cylinder chambers as well as non-linear flow through the valve. Taking into account the complexity of the model, and the fact that it is described by partial different equations, it is important to develop the program support based on numerical methods for solving this kind of problems. Simulation and program support in Maple and Matlab programming languages are conducted, and it is shown the efficiency of the results, from engineering view of point. These pneumatic systems have a lot of advantages if we compare them with the same hydraulic types; they are suitable for clean environments, and much safer. In accordance with project and space conditions, valves are positioned at relatively large distance from pneumatic cylinder. Considering real pneumatic systems, it is crucial to describe them with time delay, nonlinearities, with attempt of not creating only academic model. Despite of these problems, development of fast algorithms and using the numerical methods for solving partial different equations, as well as enhanced simulation and animation techniques become the necessity. Various practical stability approaches, for solving complex partial equations, used similar algorithms, (Dihovicni, 2006). In the third part it is described special group of distributed parameter systems, with distributed control, where control depends of one space and one time coordinate. It has been presented mathematical model of pneumatic cylinder system. The stability on finite space interval is analyzed and efficient program support is developed. Solving problem of constructing knowledge database of a decision making in process safety is shown in fourth part. It is provided analyses of the requirements as well the analyses of the system incidents caused by specification, design and the implementation of the project. Main focus of this part is highlighted on practical stability problem and conditions for optimal performance of pneumatic systems. Algorithm of decision making in safety of pneumatic systems is developed, and the system has been realized taking into account C# approach in Windows environment. www.intechopen.com Advances in Computer Science and Engineering 162 2. Representation of pneumatic cylinder-valve system Deatiled mathematical model of dual action pneumatic actuator system, controlled by proportional spool valves, is shown in paper (Richer, 2000), and it is carefully considered effects of non-linear flow through the valve, leakage between chambers, time delay, attenuation and other effects. These pneumatic systems have a lot of advantages if we compare them with the same hydraulic types, they are suitable for clean environments, and much safer. In accordance with project and space conditions, valves are positioned at relatively large distance from pneumatic cylinder. Typical pneumatic system includes pneumatic cylinder, command device, force, position and pressure sensors, and as well as connecting tubes.
The question of pole placement for glass capillary tube drawing process is considered. It is used... more The question of pole placement for glass capillary tube drawing process is considered. It is used a frequency domain approach to an arbitrary finite spectrum assignment for multivariable time delay systems in order to control glass capillary tube drawing process. The Padé approximation is used for the system of third order and time delay is eliminated from the transfer function of the process. The responses are shown as well the transfer function of the closed loop after applying finite spectrum method. By choosing state variables it is obtained non degenerative transfer function of process model. The time delays in open loop remained the same as in the closed loop. The all poles are located in the left half plane and system is stable. Appropriate program support for this type of problems is developed in Maple language. ARTICLE HISTORY Received 15 August 2016 Accepted 18 September 2016 Available online 30 September 2016
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Papers by Djordje Dihovicni