Now showing 1 - 10 of 55
  • Publication
    LASER ABLATION OF PAINT COATINGS IN INDUSTRY
    A comparison is made between the laser and sandblasting methods for removing paint from industrial facilities. The advantages of laser ablation are discussed. The possibilities of laser paint removal systems - stationary and moving - are shown. The main factors influencing the laser ablation process and the indicators that determine the quality of the obtained surface are systematized. Researchers' publications on this technological process are analyzed.
  • Publication
    Finite element modeling of laser aluminum marking
    (2021) ;
    N Angelov
    ;
    I Draganov
    ;
    A Atanasov
    ;
    A Lengerov
    ;
    ;
    I Balchev
    This work makes use of the finite element model, whose results are validated by experiments. The effect is discussed of the speed on the laser marking process. Numerical experiments are performed to determine the temperature fields produced by laser pulses on samples of aluminum, a material with wide industrial uses. The numerical calculations are performed for the cases of a fiber laser and a CuBr laser. Plots are drawn of the temperature dependence on the speed for two power densities for both lasers. Preliminary working speed intervals are determined for the power densities used.
    Scopus© Citations 1
  • Publication
    Investigation of Surface Structure in the Laser Marking Process as a Function of Speed and Raster Step
    In this research, an experiment was conducted to change the technological properties of the surface by laser marking. The influence of the speed v of 50 mm/s, 75 mm/s and 100 mm/s and the raster step Δx from 20 µm to 80 µm at a constant average power P = 19.2 W and pulse duration τ = 4 ns was investigated. These parameters during the laser marking of AISI 304L steel have a significant change in microhardness and surface roughness. High hardness was found to be achieved at higher powers and small pitch. Analysis of the results showed that as the raster step increases, the roughness of the marked sample decreases. The effect of linear energy density and overlap factor on the process was also investigated. The microhardness of the machined surfaces increases with an increase in the linear energy density and the overlap coefficient, in the first case the dependence is almost linear, and in the second - nonlinear. Varying the marking speed and raster pitch in laser surface texturing of AISI 304L steel has a significant effect on the surface hardness and roughness, changing HV from 260 HV to 766.5 HV and Ra from 1.75 µm to 4.3 µm, respectively, which are the subject of the present analysis. research.
  • Publication
    Artificial Neural Networks: What Can They Learn about Color Laser Marking?
    (2018)
    Pavels Cacivkins
    ;
    ; ;
    Martins Sperga
    ;
    Ingus Dilevka
    ;
    Artis Vitins
    Scopus© Citations 1
  • Publication
    Antibacterial and anti-viral effects of silver nanoparticles in medicine against COVID-19—a review
    (2020) ;
    Ivaylo Balchev
    ;
    Risham Singh Ghalot
    ;
    The article reviews the research on disinfecting the air through air filters and ventilation systems using silver nanoparticles (Ag NPs) (encouraged from the present situation of COVID-19) focusing on stopping the spreading of deadly viruses. The primary goal of the research is to demonstrate possible antiviral Ag NP formulations to be delivered by inhalation, to minimize the worsening of respiratory system infections. The basic design of the study includes a bibliometric analysis of the study of the effect of Ag NPs on the disinfection of viral infections. The research will discuss the idea of the use of laser ablation with Ag NPs for antiviral and antibacterial effects. The research article results in compelling evidence for the use of Ag NPs for medicinal purposes for infectious diseases/viruses and will contribute to the progress of medical science to protect healthcare workers from dangerous viruses at medical institutions. Practically, the research will generate a sterile system, which might be employed by every public or private institution economically with Ag NPs (because of their antimicrobial properties).
    Scopus© Citations 25
  • Publication
    Investigations of Properties of Powdered Ferromagnetic Sorbents
    (2015)
    J. Treijs
    ;
    ;
    V. Mironovs
    ;
    V. Lapkovskis
    ;
    A. Shishkin
    The paper examines possible application of certain disperse materials based on iron powders as ferromagnetic sorbents for collecting the oil products spilled on the water surface. Sorption ability is defined for the investigated ferromagnetic sorbents.
    Scopus© Citations 2
  • Publication
    EAST LATGALE SAA PROJECT
    (2016-12-10) ;
    Aigars Metlāns
    East - Latgale Region including Rezekne city and district and Ludza City and disrtict. East - Latgale region occupies 5241 km2 (about 8% o f Latvia). There are 120273 inhabitants (4,9% o f Latvia's population). Registration of waste volume in region is formal, because waste going to dumpsites as a matter of fact is not controlled exept dumpsites used by largest towns. In East - Latgale region in year 2000 was 46 dumpsites and total waste volume 64700 m3. National Municipal Solid Waste Management Strategy foreseeing establish 10-12 new solid waste landfills in Latvia. The overall strategy in searching for a location of a new landfill includes three principal aspects: 1. The environmental impact o f a landfill has to be as low as possible. 2. The waste disposal interests should not conflict with other interests. 3. The selected site should be reasonable from economic viewpoint. Taking into consideration the above aspects, the division of the land in areas suitable and non-suitable for location of a new landfill was based on the following criteria: Geological structure and hydrogeological conditions; Distance to urban areas; Location o f particularly protected nature objects; Distance to surface water bodies.
  • Publication
    Numerical modeling and simulation for laser beam welding of ultrafine-grained aluminium
    (2021) ; ;
    Ivo Draganov
    ;
    Nikolay Angelov
    Laser beam welding of aluminium offers huge potential for a wide variety of welding of different thickness parts with the method of thermal conductivity due to the relatively high difference between melting temperature and evaporation. However, due to the high melting temperature and good thermal conductivity of this light metal, the temperature gradients during the welding process are usually high, causing residual stresses in the weld, which can lead to undesirable deterioration of the weld pool properties and the quality of the process. Physical modelling and simulations of the laser welding process are powerful tools for gaining a fundamental understanding of the technological process. They are also a suitable tool for preliminary assessment of the intervals in which the real preliminary experiments for process optimization should take place. This work is devoted to the numerical modelling of the process of welding ultrafine-grained aluminium using a fibre laser. A three-dimensional model of the welding process was created, using the finite element method implemented in the program ABAQUS. The temperature fields at depth z and on the surface x, y in the welded samples is determined. The temperature change as a function of time for different coordinates of the weld is also analysed. During numerical calculations, the power, machining speed and diameter of the workplace are variable. The obtained results are compared with real experiments conducted in the laboratory by other researchers.
    Scopus© Citations 2
  • Publication
    Laser marking and engraving of household and industrial plastic products
    (2021) ;
    A Snikeris
    ;
    I Balchev
    ;
    Laser marking and engraving has developed in many ways into an attractive process for identifications of consumer goods made of plastic. It is a quick and inexpensive process that offers a variety of flexible options for designing identification products (barcodes, security information, codes). This report examines the possibility of marking PVC products used in the electronics industry with different colors using a CO2 laser technological system. The functional dependences of the width and depth of the marking lines on the main technological parameters – average power and processing speed, are analyzed. The analysis aims to help determine the optimal working intervals for marking and engraving by the bar coding method, as well as for the coding and reading of information on household PVC products used by visually impaired people. The analysis further aims to help determine the optimal operating intervals of speed and power when choosing a given geometry of the ablation zone in marking and engraving products for different users.
    Scopus© Citations 1