a borítólapra  Súgó epa Copyright 
Acta polytechnica HungaricaVolume 18., Issue No. 4. (2021.)

Tartalom

  • Svetlana Grigoryeva ,
    Alexander Baklanov ,
    Aslima Alimkhanova ,
    Alexander Dmitriev ,
    György Györök :

    Abstract: A new control system via light-emitting diode (LED), lighting devices, is reviewed in this article. In order to transmit data, Visible Light Communication technology was used. Function block diagrams and schematic diagrams, of transmitting and receiving optical channels were used for the temperature control. Implementation of the developed system has been accomplished by the regulation of the onsite temperature control. Serial interface of data transmission has been applied in order to provide stable and reliable link via physical channels with the usage of LED lighting devices. According to the protocol of this interface, the transmitted data transforms into consecutive impulses in the accordance with the UART standard. The present work shows that asynchronous data transmission has been carried out via microcontrollers. In order to conduct the experiment presenting controlling possibilities via white LED lighting, a breadboard prototype with two modules - transmitter and receiver - has been created. The conducted measurements have shown that optical channel of data transmission has high reliability, while the illumination level does not change. There is no flickering and a comfortable lighting regime is provided.

    Keywords: control system; data transmission; lighting devices; LED; Visible Light Communication; temperature

  • Yuan Sun ,
    Chih-Min Lin :

    Abstract: This study presents a multidimensional classifier design using a fuzzy brain emotional learning model, combined with a particle swarm optimization (PSO) algorithm that allows a network to automatically determine the optimum values for the weights of the reward signal. The multidimensional fuzzy brain emotional learning classifier(MFBELC) is first described with corresponding fuzzy inference rules; then the PSO algorithm is applied for the optimum parameter choice. This PSO-MFBELC is evaluated for the Wine dataset and Iris dataset, which are publicly available from the UCI machine learning database. A comparison of simulations using the proposed PSO-MFBELC shows that this classifier is superior to other algorithms in the recognition accuracy aspect.

    Keywords: brain emotional learning model; fuzzy inference system; particle swarm optimization algorithm; multidimensional classifier

  • Miroslav Spodniak ,
    Ladislav Főző ,
    Rudolf Andoga ,
    Karol Semrád ,
    Károly Beneda :

    Abstract: Jet engines are nowadays one of the most popular ways of propulsion for aircraft. This type of propulsion is widely used also in other sectors of industry. The main challenging task for designers is to design reliable and also powerful propulsion units. There are many manners for increasing the thrust of the particular jet engine and one of them is water injection into the compressor. In order to design such a system, it is necessary to have information about the flow parameters in the compressor. The proposed article deals with the CFD modeling of the radial compressor in order to estimate flow parameters for further research in the field of increasing thrust. One of the aims of the article is to develop a numerical model of the compressor and carry out the numerical analysis using CFD software ANSYS CFX. The analysis can be in further research performed multiple times for multiple regimes and results can be compared with the experimental measurements of thermodynamical values if the proper CFD model is developed. The main target of the paper is to establish the methodology for the amount of water estimation for particular engines. The methodology is introduced in the third chapter of the paper. Following the CFD model presented in the article and the methodology for water amount estimation, further research is presented in the fourth chapter of the article.

    Keywords: temperature model; pressure model; CFD simulation; water injection system; centrifugal compressor

  • Nikolett Fecser ,
    István Lakatos :
    Cavitation Measurement in a Centrifugal Pump63-77en [734.32 kB - PDF]EPA-02461-00109-0040

    Abstract: One of the causes of centrifugal pump instability lies in the phenomenon of cavitation. Cavitation in the centrifugal pump can produce undesirable effects such as deterioration in hydraulic performance. In order to prevent the emergence of cavitation, it is required to know the onset point of the cavitation, in the pump. Our study presents the process and result of the cavitation measurement performed on a centrifugal pump in a closed loop test system. In this study, we applied CFD analysis, which serves as a means of measuring flow in the impeller of the centrifugal pump. The results gained from CFD analysis correspond, approximately, to the measured results.

    Keywords: centrifugal pump; cavitation; NPSH; CFD

  • Sorina Gabriela Șerban ,
    Imre Kiss :

    Abstract: Maximal recovery of iron contents waste is an important problem in siderurgy, since its needed transformation into by-products, thus into valuable economic goods, can lead to a rational exploitation of raw material, thus, ensuring industrial needs, as well as environmental protection. Powder waste can be processed in the form of pellets or briquettes and then is used in the steelmaking processes. Thus, the powdery ferrous wastes resulting from the materials industry, from the point of view of granulation, corresponds to processing by pelletization. In line with the superior recovery of waste, our research has focused on identifying the possibilities for the pelletization of industry related the small and powdery iron containing waste that exists in very large quantities, in Hunedoara County area (Hunedoara and Calan) and beyond. This article presents the results relating to the possibilities of pelletization, of industrial small and powdery iron containing waste, from the steel industry (steel dust, mixed agglomerating and blast furnace dust, landfilled in siderurgical ponds, in vicinity of the former industrial areas of Hunedoara and Calan, Hunedoara County). The origin of the material is the minerals (bauxite residue / red mud, landfilled in vicinity of Oradea, Bihor County) or from metal surface treatment operations (coating anticorrosive dust, collected in Oradea) in the industry. The waste utilized in the laboratory experiments was processed using a series of installed equipped in the laboratories at the Faculty of Engineering in Hunedoara, University Politehnica Timisoara.

    Keywords: steel dust; mixed agglomeration and blast furnace dust; bauxite residue (red mud); anti-corrosive sludge; pelletizing process; experimental pellets; compression test

  • Benedek Nagy ,
    Péter Szokol :

    Abstract: This paper presents a new genetic algorithm for the minimum vertex cover problem. It uses interval-valued fitness and greedy error correction to obtain phenotypes (candidate solutions). By the interval-valued fitness the fitness of the candidate solution is measured not only for the whole graph, but for some of its disjoint subgraphs. A new candidate solution is obtained from those subgraphs that have the best performance among the subgraphs of the candidates with the same set of vertices. The interval-valued fitness accelerates the search effectively for graphs with a great deal of nodes and relatively small numbers of edges. In the presented algorithm we prefer to distinguish genotypes and phenotypes and do not use Lamarckian inheritance. Phenotypes are easily generated by greedy error correction from the genotypes and, in this way, a larger variety of genomes can be used during the process.

    Keywords: genetic algorithm; minimum vertex cover; interval-valued fitness; phenotypes; memetic algorithm

  • Zsolt Ercsey ,
    Albert Nagy ,
    József Tick ,
    Zoltán Kovács :
    Bus Transport Process Networks with Arbitrary Launching Times125-141en [697.98 kB - PDF]EPA-02461-00109-0070

    Abstract: The current paper is about a process network synthesis solution for a bus transport problem, where arbitrary launching data are given in an available timetable. Here, the bus transport problem is presented as an application of the p-graph methodology and is investigated from structural point of view. Focusing on the synthesis step, the bus transport process network is generated and detailed. Based on the maximal structure of the problem a mathematical programming model is generated which has the advantage of a smaller number of variables and constraints than the conventional mathematical models for similar problems. The solution of the mathematical programming model, results in the optimal solution of the bus transport problem. From the traffic point of view, an example of medium difficulty is solved, by a publicly available solver.

    Keywords: optimization; mathematical programming model; process network; p-graph; synthesis; bus transport

  • Réka Trencsényi ,
    László Czap :

    Abstract: One of the trends of the current generation of machine speech, is articulatory speech synthesis, that is based on the processing of visual and geometric information, related to voice production. Accurate knowledge of the static and dynamic geometric parameters of the vocal organs, plays a fundamental role in the realization of speech synthesis. Appropriate sources of visual extraction of these data can be MRI and ultrasound (US) records made during speech, which can be described by different geometries. Harmonization of the geometries of MRI and US frames is not a trivial task. In this publication, we present one possible method for the transformation between the two sources. The starting point of the transformation process is formed by tongue contours obtained by automatic algorithms. Beyond this exact method, we also follow statistical procedures, by applying machine learning to interconnect MRI and US records.

    Keywords: articulatory speech synthesis; tongue contour tracking; machine learning; dynamic MRI and US records; harmonization of MRI and US sources

  • Goran Otić ,
    Goran Jovanov ,
    ®ivoslav Adamović ,
    Nemanja Jovanov ,
    Stevo Jaćimovski :

    Abstract: The basis for proactive maintenance in thermal power plants, is the analysis of the root cause of the failure, i.e. the determination of mechanism and cause of failure occurrence from the thermal power plant system. The root causes of system failures can be eliminated in this way, and the causes of failures can gradually be eliminated using an engineering approach from any assembly of device or machine. Successful proactive maintenance programs would gradually, over time, eliminate problems of the device by project-engineering solutions, which, as a consequence, would have a significantly longer device life cycle, reduced downtime and increase production capacity.

    Keywords: proactive maintenance; life cycle management; life cycle costs; vibration control; reliability

  • Karolina Kaszás-Laľetić ,
    Dragan Kljajić ,
    Nikola Djurić ,
    Miroslav Prąa :

    Abstract: This paper presents the analytical and numerical calculations of the current distribution and impedance per unit length in real, multi-layer and two-layer homogeneous grounds. Realistic situations consisting of different thicknesses of ground layers were considered in these calculations. Combinations of parameters were considered at frequencies between 50 Hz and 2500 Hz (the 50th harmonic, of the basic frequency). Calculations were conducted by applying a software tool developed previously for a homogeneous ground, based on a combination of analytical and numerical mathematical procedures and modified, using boundary conditions. The problem was also solved numerically by applying the COMSOL Multiphysics software package, based on FEM. The results are validated by comparing them with the results obtained from empirical formulae applied in practical cases.

    Keywords: Stratified ground; Two-layer soil; Current distribution; Ground return impedance; Poynting vector flux

  • András Molnár ,
    István Lovas ,
    Zsolt Domozi :

    Abstract: Everyday used cheap thermal cameras can only take low-resolution images. Low-resolution images can be used as the input data of photogrammetry procedures with difficulty or cannot be used at all, as little information is stored of the actual object. Based on the little amount of information, conventional procedures are not capable of identifying a correlation between individual images. Intensity also differs between individual pixels compared to conventional RGB images, thus gradient-based solutions fail to be successful. A method has been developed, which can be used to create thermal image orthophotos from thermal images combined with RGB images. The procedure can result in several output images, from which the most important is the false color thermal image, which is within the visible light spectrum, as on it the original object and the amount of thermal radiation are both visible. Another advantage of the procedure is that not only the information of the visible light spectrum can be visualized but also the data which is invisible to the naked eye.

    Keywords: thermal photogrammetry; picture fusion; data visualization; 3D objects; low-resolution

  • Danial Mohammadzadeh S. ,
    Nader Karballaeezadeh ,
    Amirhossein Sanaei Zahed ,
    Amir Mosavi ,
    Imre Felde :

    Abstract: Urban train infrastructures are very important for reliable urban mobility. This paper proposes a three-dimensional modeling of mechanized drilling corridors. Drilling in urban areas is always a risky and complex project. One of the most important issues during the construction of subway tunnels is the investigation of the impact of drilling steps on the ground subsidence and impact on existing structures. For this purpose, different types of mechanized drilling methods are often used, resulting in a considerable reduction in the displacements caused by tunnel drilling. In this study, part of the route of an urban train tunnel, that passes under a traffic interchange, is examined. The shear strength capacity of the slab pile was calculated, using the relevant equations, and then, the modeling of the soil mass was performed, using the PLAXIS 3D finite element program. The proposed depth of the tunnel construction, by the consulting company, is 18 meters. Due to drilling problems, a depth of 14 meters has been suggested as an alternative. Analysis of both the depths of 14 and 18 meters, showed that the displacements at both depths, were approximately the same. However, the impact of the tunnel, on the capacity of the piles' tip, at a depth of 18 meters, is greater than at the depth of 14 meters. Thus, the suggested optimum depth is 14 meters, which is more suitable, than the initial suggested depth of 18 meters.

    Keywords: Tunnel; mechanized drilling; optimization; urban train lines; computational mechanics; smart cities;PLAXIS 3D; numerical simulation; finite element simulation

  • Svetlana Grigoryeva ,
    Alexander Baklanov ,
    Aslima Alimkhanova ,
    Alexander Dmitriev ,
    György Györök :

    Abstract: A new control system via light-emitting diode (LED), lighting devices, is reviewed in this article. In order to transmit data, Visible Light Communication technology was used. Function block diagrams and schematic diagrams, of transmitting and receiving optical channels were used for the temperature control. Implementation of the developed system has been accomplished by the regulation of the onsite temperature control. Serial interface of data transmission has been applied in order to provide stable and reliable link via physical channels with the usage of LED lighting devices. According to the protocol of this interface, the transmitted data transforms into consecutive impulses in the accordance with the UART standard. The present work shows that asynchronous data transmission has been carried out via microcontrollers. In order to conduct the experiment presenting controlling possibilities via white LED lighting, a breadboard prototype with two modules – transmitter and receiver – has been created. The conducted measurements have shown that optical channel of data transmission has high reliability, while the illumination level does not change. There is no flickering and a comfortable lighting regime is provided.

    Keywords: control system; data transmission; lighting devices; LED; Visible Light Communication; temperature