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Acta polytechnica HungaricaVolume 17, Issue No. 3. (2020.)

Tartalom

  • Monika Bolińska ,
    Paweł Dykas ,
    Grzegorz Mentel ,
    Tomasz Misiak :

    Abstract: The goal of this paper is to develop the neo-classical Solow growth model, in which, the authors repeal an assumption of a constant rate of growth of technological progress. Herein, the authors assume an alternative trajectory of an increase in scientific and technical knowledge A(t), and on that basis, they accept the following assumptions. First, the rate of growth of technological progress is not constant, but changes over time. Second, the path of the growth of the scientific and technological knowledge tends toward a certain level in the long term, which can be equated with the equivalent of the technological boundary. Such a modification of the assumptions regarding the technological progress rates, allows leading growth paths for both capital and product per unit of effective labor. Next, based on the solution of the presented growth model, the authors calibrated the parameters and carried out numerical simulations. Numerical simulations, conducted for the Polish economy in a 100-year horizon, allowed an inclusion of scenarios regarding both the rate of technological progress and investment rates. In the simulations, two variants of the annualized rates of technological progress were adopted (optimistic, g=1.7% and realistic, g=1.5%). The adopted levels of technological progress rates were used to determine the horizontal asymptote for the scientific and technological knowledge A(t) that will be shaped in accordance with geometric progress. In the considered variants the following investment rates were adopted: 15, 20 and 25%. This allowed determining the trajectories of labor productivity growth in the Polish economy taking into account different combinations of changes in the rates of technological progress and investment rates.

    Keywords: trajectories of labor productivity; variable rates of technological progress; gamma function; numerical simulations

  • József Dombi ,
    Edit Tóth-Laufer :

    Abstract: Fuzzy-based control systems are popular in practical applications where imprecision, subjectivity, and uncertainty can arise in the data and in the evaluation process, and it needs to be addressed. One possible solution is the fuzzy approach. However, computational requirements of these models can be extremely high, mainly defuzzification part of the Mamdani-type control. Whatever great advantages the Mamdani model has, it is closer to the human way of thinking compared to the Sugeno model, which is another popular controller. In the case where a short reaction time is required, the computational needs should be reduced. Here, we propose modified Mamdani models for this purpose. This new model is much faster while all the advantageous properties of the original Mamdani model are retained, and in some ways, it is better.

    Keywords: fuzzy control; Mamdani control; arithmetic-based control

  • Zoran Bobar ,
    Darko Božanić ,
    Ksenija Djurić ,
    Dragan Pamučar :

    Abstract: Methods of ranking and evaluation of the effectiveness of Social Media (SM) given and applied in this paper are the basis for the selection of online media that the public administration uses when communicating with citizens. The methodology presented is based on multicircular decision-making using the Fuzzy Analytical Hierarchical Process (fuzzy AHP) - Z number model - Fuzzy Multi-Attributive Border Approximation Area Comparison (fuzzy MABAC), which eliminates the traditional intuitive ratings of PR services. This resulted in poor use of available channels of communication or ineffective communication. Positive results of the application of presented methods are especially evident in increasing the number of channels of communication on the Internet and the realization of communication goals for greater participation of citizens in public administration.

    Keywords: Internet; Social Media; Fuzzy Analytical Hierarchical Process (fuzzy AHP); Fuzzy Multi-Attributive Border Approximation Area Comparison (fuzzy MABAC); Z-number

  • Csaba Kárász ,
    József Kopják :

    Abstract: The aim of this study is to highlight the correlations among the main parameters of lighting systems, for the agricultural industry. With these data, engineers could enhance the efficiency of their light source, in regards to different plant types. Statistical analysis has been conducted on the results of several experiments to find out if there is any correlation among different LED driver settings, which could affect light source design. The experiments have been re-grouped according to plant types and used variables. Two major groups have been examined: the experiments made with lettuce and with microalgae (in which most studies were made in the topic of photo-bioreactor enhancement). Smaller, sub-groups, have been clustered together with similar test variables as well. Significant correlations have been found between the variables of: light intensity (photosynthetic photon flux density) and photoperiod, light intensity and frequency, and light intensity and light spectrum as well. The results are in congruence with other studies and the summary of the analysis could be used to optimize light source design.

    Keywords: Indoor Plant Cultivation; PPFD; Photosynthesis; Pulse Width Modulation, LED light source driver

  • Zdzisław Chłopek ,
    Jakub Lasocki :

    Abstract: The heat release characteristics of the combustion process in a four-stroke compression-ignition engines depend strongly on the fuel injection strategy. In the case of multiple fuel injection, deviations from the classic heat release model applicable to a single injection are observed. This paper presents the results of empirical tests and their analysis for a single-cylinder compression-ignition research engine with double injection of fuel. The influence of fuel injection pattern on the indicated pressure has been analyzed, in particular the derivative of indicated pressure in respect of the crank angle. The processes of fuel supply and heat release have been investigated in time domain. A correlation analysis of voltage controlling the opening of injector and unit heat release rate have been presented. The delay angle and delay time of unit heat-release rate in respect of the voltage controlling the opening of the injector have been determined. The heat release for each injected fuel dose has been analyzed.

    Keywords: heat release; compression-ignition engine; multiple fuel injection; ignition delay

  • Zsolt Mitrik ,
    Péter Kádár :

    Abstract: During the development tests of high voltagecircuit-breakers (HVCB), the manufacturers obtain a large amount of information regarding the behavior and parameters of the equipment. Such valuable conclusions can be deduced from processing, analyzing and evaluating them by scientific methods that are appropriate for developing a new decision-supporting model. The Author describes the methodology of the development process of such part of the new decision-supporting model (Circuit Breaker Design algorithm CBDa) which systematizes and evaluates the information from tests as results and illustrates the possible ways of usage.

    Keywords: HVCB; 3rdgeneration SF6 circuit-breaker; CBDa model

  • Judith Jakob ,
    József Tick :
    Camera-based On-Road Detections for the Visually Impaired125-146en [699.40 kB - PDF]EPA-02461-00098-0070

    Abstract: Herein, we research the possibilities of assisting visually impaired pedestrians moving in traffic situations by using camera-based detection of relevant objects in their immediate surroundings. Therefore, we use and adapt algorithms from the field of driver assistance. We present a road background segmentation based on watersheds, whose results are used as input for the presented crosswalk and lane detection algorithms. The crosswalk detection is based on the application of two 1D mean filters and the lane detection on local computations of the EDF (Edge Distribution Function). In our evaluation, the described algorithms achieved good hit rates of 99.87% (road segmentation), 98.64% (crosswalk detection), and 97.89% (lane detection).

    Keywords: ADAS; Driver Assistance; Visually Impaired; Road Segmentation; Crosswalk Detection; Lane Detection; Computer Vision

  • Mustafa Tekin ,
    Mustafa Sekkeli :

    Abstract: One of the most studied and funded renewable energy sources is solar energy, all over the world. Solar panels are used to obtain electrical energy from the sun. They should be used effectively due to their expensive structure and challenging installation. However, as the sun light only reaches to the earth during daylight hours, solar systems cannot generate active power during the night, or in cases where daylight is not enough, the whole power capacity of the solar inverters have not been used. In this study; it was shown that in addition to the active power generation during the daytime hours, the solar systems were able to generate reactive power with the remaining capacity of the inverter. Thereby adjusting the grid voltage was provided by the solar system’s reactive power control. Designed solar system generates completely reactive power at nights. Thus, the efficiency of the solar systems has been increased by ensuring that the solar systems have used to keep the grid voltage within the values, which stated in the standards, by producing reactive power as well as active power. Matlab/Simulink was used to model the system when using hysteresis band method for system control.

    Keywords: power grids; reactive power control; renewable energy sources; solar system; voltage control

  • István Bodnár ,
    Dániel Koós ,
    Patrik Iski ,
    Ádám Skribanek :

    Abstract: The current study is dedicated to the realization and development of an ASTM E972 standardized, class C sunlight simulator. Sunlight simulators or sun simulators are laboratory devices used to study solar cells. Our sun simulator is suitable for the examination and qualification of solar cells, with an area of 150 mm x 150 mm. It consists of 4 LED blocks of different colors and a halogen reflector. The completed sun simulator is validated; the design and realized parameters display good matching.

    Keywords: sun simulator; solar simulator; solar cell tester; halogen; LED

  • Paul Arévalo Cordero ,
    Juan Lata García ,
    Francisco Jurado :

    Abstract: Distributed generation represents an optimal solution for energy problems in remote sites, where access to energy distribution companies is difficult. This article therefore presents the modeling and optimization of an electric power system based on hybrid renewable energy (photovoltaic/hydrokinetic/diesel), combined with a Lithium Ion battery storage system. The analysis is performed using two methods. The first is a computational model based on mathematical equations using the Simulink Design Optimization (SDO) tool in Matlab. The second is a simulation of the hybrid system using the HOMER Software. The results show that the highest annual energy contribution corresponds to the hydrokinetic generation system (78.87%), the photovoltaic generation with a percentage of 19.59% and the penetration of the diesel generator is the lowest with 1.53%. In addition, the Nelder-Mead algorithm (SDO) shows a lower number of diesel generator starts, increasing the capacity of the batteries.

    Keywords: Hydrokinetic turbine; Solar panels; Renewable energy; Hybrid System

  • Róbert Pethes ,
    Levente Kovács :
    Voting to the Link: a Static Network Formation Model207-228en [675.97 kB - PDF]EPA-02461-00098-0110

    Abstract: It is well known that the structure of social, organization and economic networks have a huge effect on the behaviour of the underlying system. This structure is often considered as a network, and modelling the formation of these networks is an active research area of complex systems. In this paper we present a simple network generation model: there is a closed population of agents, and the agents are voting to the connections according to their fixed preferences. These preferences are denoted by real numbers, and can be considered as simply the desired number of connections or social capital.

    Keywords: static random graph model;inhomogeneous random graphs; social networks

  • Kristína Machová ,
    Marian Mach ,
    Miroslava Hrešková :

    Abstract: The paper is from the field of anti-social behavior recognition in online discussions. It focuses on the extraction of knowledge about special web reviewers as authorities or trolls, and trying to distinguish one from the other, based on their opinions and credibility. This paper presents a statistical application of supervised learning for creating a prediction model applied to find authorities (or trolls) among authors of online comments. The model can be used for differentiating between authoritative and non-authoritative reviewers. Standard methods, such as linear and logistic regression and genetic programming were applied. The objective of designed approach is to model dependency of the reviewer variable on independent predictors representing special reviewing. Values of those independent predictors (variables) are extracted from the data about structure as well as text content of online discussions. The model can offer important information for social web users, who search for truthful and reliable information, while in the process of developing their own opinions.

    Keywords: reviewers classification; authority; troll; linear regression; logistic regression; genetic programming