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APPLICATION OF NEURAL NETWORKS TO THE OPTIMIZATION OF THE THERMAL TREATMENT PROCESS OF WOOD MATERIALS M. Hadjiski, N. Deliiski, A. Grancharova Key Words Wood thermal treatment process; optimization; neural networks. Abstract In this paper, a software system for 2-dimensional and 3-dimensional modeling of frozen and not frozen logs and prismatic wood materials is used as a basis for optimization of the thermal treatment process of such materials. Then, the dependence of the optimal heating time on various parameters is approximated by means of neural networks. This would allow a fast real-time computation of the optimal heating time instead of performing extensive numerical simulations of the model comprised of partial differential equations. Article PDF Download article (PDF)

SYNTHESIS OF FUZZY CONTROLLER FOR CROSS-FLOW WATER TURBINE K. Ormandzhiev, S. Yordanov, S. Stoyanov Key Words Automatic system; cross-flow turbine; transient processes; fuzzy controller. Abstract The paper deals with a developed mathematical model describing the operation of automatic system for controlling of cross-flow water turbine in laboratory conditions. Fuzzy governor is synthesized and the transient processes in the system are compared toward these ones during utilization of classical PD controller. The results from numerical experiment are presented in graphical form. Article PDF Download article (PDF)

GLOBAL OPTIMIZATION ALGORITHM BASED ON ONE-DIMENSIONAL CHAOTIC MAPS AND GRADIENT DESCENT TECHNIQUE D. Tsankova, S. Lekova Key Words Global optimum; multimodal function; chaos; gradient descent method. Abstract A hybrid algorithm for searching the global minimum of a multimodal function is proposed in the paper. It is a two stages search technique, the first stage is the twice carrier wave based chaotic optimization algorithm (COA) for global searching, and the second stage is the gradient descent algorithm (GDA) for accurate local searching. The chaotic dynamics is realized through one-dimensional map in three variants: logistic, cubic and sine map. Three testing functions are used. A hundred simulations (each starting from different initial point generated randomly) were carried out for each of the test functions using two optimization algorithms: the proposed hybrid algorithm and the GDA working alone. The success and accuracy of locating the extremum, as well as the convergence of the algorithms using the three different chaotic maps were discussed Article PDF Download article (PDF)

ARCHITECTURE EVOLUTION THROUGH DYNAMIC RECONFIGURATION IN JADL A. Papapostolu, D. Birov Key Words Software architecture; component-and-connector view; software evolution; dynamic reconfiguration; ADL; context-oriented software development Abstract In software architecture the dynamic structure of a software system can be described in terms of components and connectors and expressed through the use of Architectural Description Languages (ADLs). We present jADL, a new ADL, designed for the creation and validation of dynamic and mobile architectures. It, also, aims to help towards the process of “unifying” the definition and implementation of an architecture in a way that the final result is consistent with the architecture in terms of both functional requirements and quality attributes. In this paper, we examine into details the definition and expression of jADL’s architectural elements; components, connectors, ports, roles and behaviour describing statements – attach, detach, config, bind. The attributes of synchronicity and multiplicity concerning the connections between architectural elements are presented. A special case of connections is presented – the bind statement and the construction of composite architectural elements. Also, a case study of the client-server dynamic model in jADL is presented and the possibilities of jADL for dynamic reconfiguration are explored. Article PDF Download article (PDF)

NETWORK SIMULATOR FOR BOTNET DOS ATTACKS Y. Aleksieva, H. Valchanov Key Words Botnet; DoS attacks; network security; network attacks simulator. Abstract The most serious appearance of modern malware is Botnet. Botnet is a fast growing problem that is still not well understood and studied. One widely spreading variant of the botnet attacks is an IRC botnet. There are a number of techniques to detect botnet attacks and infections, but they do not have the functionality to prevent malicious botnet activity. The development of a quality equipment to detect and remove botnet infection needs a good simulation environment that is safe and fully meets the functionality of botnet DoS attacks. The paper presents the features of the implementation of network simulator for DoS attacks. The simulator allows creating different attacks with various parameters. Some performance experiences are performed and the obtained results are shown. Article PDF Download article (PDF)