Petar PRVULOVIĆ, Nemanja RADOSAVLJEVIĆ, Djordje BABIĆ
Wireless sensor network applications are numerous and range from monitoring traffic and production facilities to monitoring the health condition of patients. Their main task is to collect and send the read values from the monitored area to the base station. As decisions are made based on the collected data, it is necessary to pay attention to the aspect of communication security, so that the collected data can be safely transferred through the network, from nodes to base station. Sensor nodes typically have limited power. Cipher algorithms should be chosen so that the required level of security is achieved with the minimum possible energy consumption for communication encryption. For these purposes, the category of lightweight cipher algorithms has been recognized. In this paper, we compare block cipher algorithms that, due to their low hardware and energy requirements, find their application, especially in wireless sensor networks. The main focus of this paper is an overview of block cipher algorithms based on a substitution-permutation network.
Nedžmija DEMIROVIĆ, Zlatan IBRIŠIMOVIĆ, Izudin SOFTIĆ, Nerdina MEHINOVIĆ
In order to achieve maximum efficiency of photovoltaic systems, maximum power point (MPPT) monitoring is needed. Algorithms implemented in photovoltaic systems take into account changing operation conditions, load values and they regulate the voltage thus allowing operation at the maximum power point. The aim of this paper is to evaluate the performance of the three most common algorithms for maximum power point tracking: perturb and observation P&O, incremental conductance and fractional open-circuit voltage algorithm.
In the simulation model of a PV system, the influence of the maximum power algorithms on the output characteristics in the case of a significant change in external parameters is shown.
Pavle STEPANIC, Radomir RADISA, Aleksandar RAKIC, Jelena VIDAKOVIC, Srecko MANASIJEVIC
Sustainability, one of the most important aspects of every production plant, can be enhanced through retrofitting. In this paper, retrofitting of two furnaces for metal heat treatment, namely vacuum furnace and conveyor belt furnace with protective atmosphere, are presented. The goal of the revitalization of the furnaces is modernization through the digital transformation of technological process variables as a new form of data availability in the context of Industry 4.0. The application of a modern control system based on a programmable logic controller ensures optimal control of the technological process which significantly extends the useful life of the machine. For the vacuum furnace, the replacement of a dilapidated vacuum system is also performed.
Radomir ĐOKIĆ, Jovan VLADIĆ, Tanasije JOJIĆ, Dragan ŽIVANIĆ
During the exploitation, one can encounter different types of vertical transport machines, from mining and contemporary passenger elevators with extreme heights and lifting velocities to the classic elevators with relatively small parameter values which leads to the usage of different dynamic models and mathematical methods for their solving. Analysis of the vertical transport systems and machines means that we must form mathematical models with systems of differential and algebraic equations. The paper presents the issues with mechanical models of the vertical transport systems (elevators and the mining elevators) and numerical methods for formed mathematical models solving according to basic parameters of exploitation facilities in mines.