INSTITUTIONAL REPOSITORY OF

RĒZEKNE ACADEMY OF TECHNOLOGIES

The repository aims to uphold the principles of open science, compile the outcomes of scientific endeavors and research data, provide online access to the results of RTA's scientific activities, facilitate the dissemination of RTA's scientific achievements, and support the development of scientific activities while ensuring compliance with the FAIR data principles for research data management.

 
Research outputs
754
Projects
1
People
27
Recent Additions
  • Publication
    Apstrādes rūpniecības mazo un vidējo uzņēmumu snieguma novērtēšana Latvijā. Promocijas darba kopsavilkums
    (2023)
    Kotāne, Inta
    ;
    Mietule, Iveta
    Mūsdienās Latvijas uzņēmumu ekonomisko situāciju un darbību kopumā būtiski ietekmē pasaules un Eiropas ekonomiskā vide, ekonomisko procesu globalizācija un ārējās vides pastāvīgas izmaiņas. Vieni no aktīvākajiem pārmaiņu virzītājiem Latvijas ekonomikā ir mazie un vidējie uzņēmumi (MVU), turklāt tieši MVU ir visneaizsargātākie no ārējās vides pastāvīgajām pārmaiņām. Tirgus konkurences saasināšanās apstākļos vitāli būtiski ir spēt laikus reaģēt uz tirgus izmaiņām, tādējādi MVU meklē iespējas minimizēt iespējamos zaudējumus un pievērš arvien lielāku uzmanību savu uzņēmumu darbības novērtējumam. Promocijas darba aktualitāti noteica nepieciešamība pilnveidot Latvijas apstrādes rūpniecības MVU snieguma novērtēšanu, izstrādājot pētniecībā balstītu apstrādes rūpniecības MVU snieguma novērtēšanas indeksa metodoloģiju.
  • Publication
    Determination of the optimal mode of laser surface marking of aluminium composite panels with CO2 laser
    (2022)
    Emil Yankov
    ;
    Roussi Minev
    ;
    Nikolay Tonchev
    ;
    Lyubomir Lazov
    This research examines an approach for finding the optimal modes of laser treatment with CO2 laser on advertisement boards made of aluminium composite panels. To achieve the optimal area of the processing mode, an experimental methodology has been developed and an experiment has been planned for finding the limits at the given parameters of the speed and power to obtain an optimisation model. The optimal results are obtained at speeds from 100 to 200 mm/s along the x and y operative axes, as well as the power limits from 5 to 7.5 W to obtain a clear and well-defined image. The defined theoretical mode, obtained because of multicriteria optimisation, is implemented in practice. It is defined as having the relatively best quality image obtained in the shortest time.
  • Publication
    APPLICATION OF A FINITE ELEMENT MODEL TO OBTAIN THE INFLUENCE OF THE TREATMENT’S POWER, REFLECION AND FOCAL DIAMETER IN LASER TEXTURING OF ALUMINUM
    (2023)
    Lyubomir Lazov
    ;
    Ivo Draganov
    In this work, a numerical model of laser texturing is considered. A finite element model of a representative sample of pure aluminum was created. The impact of a laser pulse was simulated, assuming a Gaussian volume distribution of the heat flux. Material properties are assumed to be constant and latent heat is accounted for. Results are obtained for the thermal field and the width of the vaporized zone, assuming that the crater is characterized by its maximum width. The numerical model was used to study the influence of pulse power density, reflection, focal diameter and pulse duration. The ablation threshold at different laser pulse durations was determinate.
  • Publication
    Investigation of the influence of the processing speed and the linear pulse density of the laser surface texturing process
    (2023)
    I Adijāns
    ;
    L Lazov
    ;
    M Ilieva
    ;
    M P Nikolova
    Fine-tuning laser parameters is necessary to achieve the desired quality of the process of laser surface texturing. This requires a set of experiments to assess the influence of the main process parameters on the quality of the surface of a treated alloy. By varying the laser parameters, different laser-material interactions, such as heating, melting, or evaporation can be observed. This study analyzes the influence of two interrelated processing parameters in laser surface texturing – the speed of beam motion on the surface on the one hand, and, on the other, the linear pulse density. They ultimately have a direct impact on the resulting microstructure, hydrophilicity, and electrochemical properties of austenitic steel (AISI 304). By adjusting the pulse repetition rate of a 1064-nm fiber laser from 500 kHz to 1000 kHz at a constant speed of 100 mm/s, the surface wettability changes from hydrophobicity to hydrophilicity. All surfaces treated with laser scanning speeds varying from 20 mm/s to 200 mm/s at a constant rate of 500 kHz are hydrophobic. As a result, the changed ability to repel liquids alters the corrosion properties of the steel in a 0.5 M H2SO4 solution. The results allow one to distinguish ranges of laser-beam parameters that could be useful in selecting certain properties of the stainless-steel surface layer.
  • Publication
    Estimation of the most influential factors on the laser cutting process heat affected zone (HAZ) by adaptive neuro-fuzzy technique
    (2016)
    Dalibor Petković
    ;
    Vlastimir Nikolić
    ;
    Miloš Milovančević
    ;
    Lyubomir Lazov
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