Scientific papers (IF)

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3D SCANNERS. DIVERSITY AND OPERATING PRINCIPLES
(2017)
Aksjonovs, Artēmijs
;
Zaicevs, Edgars
;
Martinovs, Andris
The paper deals with existing 3D scanners classification and types. Each 3D scanner given the principle of operation. It examines the scope of application of different type scanners advantages and disadvantages. The aim was based on this data to create a 3D scanner prototype, by means of which an ordinary user can conveniently and easily scan a small, straightforward form objects.
A Review of Methods for Reduction of Polycyclic Aromatic Hydrocarbons from Waste Water and Flue Gases
(2015-08-06)
Teirumnieks, Edmunds
;
I. Semjonova
This review describes methods which can be used for the reduction of the polycyclic aromatic hydrocarbon (PAH) emissions from wastewater and flue gases including principles of operation of the methods and studies of their effectiveness. There are discussed both methods, which nowadays are already used industrially, and their improvement opportunities as well as recent technological trends in this field. The methods have been classified into two main categories: flue gas treatment and wastewater treatment.
Scopus© Citations 1
ANALYSING THE INFLUENCE OF TECHNOLOGICAL PARAMETERS ON THE PROCESS OF LASER MARKING OF SURFACE OF ANODISED ALUMINIUM SAMPLES
(2023)
Ļubova Denisova
;
Antons, Pacejs
;
Emil Yankov
;
Lazov, Lyubomir
The requirements for marking in terms of contrast and durability are constantly increasing. In order to meet all these challenges, it is necessary to carry out research leading to the optimisation and increase in efficiency of the technological process of laser marking. In the case of aluminium, the contrast and durability of the marking depend on the values of the laser marking parameters. In order to determine the optimal laser marking method, experimental studies have been carried out, controlling the power, speed, frequency, pulse duration and line raster step for a specific anodised aluminium. The studies carried out were analysed and subsequently optimized to obtain a contrast marking. A Rofin PowerLine F 20 Varia fiber laser system and aluminium alloy 1050 with anodised surface were used for the research. The surface changes after the laser treatment were analysed using a laser scanning microscope and contrast determination method. The dependence of contrast and roughness on speed, power, frequency and raster step was analysed. Comparative plots of contrast and roughness variations versus laser marking technological parameters were constructed.
ANALYSIS OF LASER PROCESSING OF ARTIFICIAL LEATHER
(2019)
Pāvels Narica
;
Ruta Laizāne
;
Antons, Pacejs
;
Mežinska, Silvija
With the development of laser technologies, the field of application of lasers is developing as well. They are capable of processing numerous materials and are still finding their application in unexpected areas. In this case, lasers are studied as a system with which black and white color artificial leather can be processed. This modern material allows you to combine comfort, practicality and reasonable price in a finished product. The manufacturer of artificial leather provides wide possibilities of design. In this study laser beam was used for dark and light laser markings on black and white color artificial leather and in this work, it could be observed how CO2 and fiber laser processing influence this specific material.
Scopus© Citations 1
Analyze of Leachate Composition in the Dumpsites of East-Latgale Region
(2003)
Teirumnieks, Edmunds
;
Teirumnieka, Ērika
There are are 28 working or closed but not recultivated municipal solid waste dumpsites in East-Latgale now. A number of these dumpsites are situated near lakes, rivers, in old mineral quarries etc [3, 6]. All these dumpsites pollute groundwater, soil and present danger for human health. One of the dangerous factors is leachate which is generated in these dumpsites and which pollutes groundwate, soil and drinking water. The analysis of leachate sample chemical content in the biggest East-Latgale dumpsites “Ritini”, “Zvirgzdene”, “Zelceva” and “Mostovaja” has been done in 2002. The content of leachate depends on content of waste, dumpsite management etc. The most polluted leachate is in the biggest dumpsites of region – “Ritini” and “Zvirgzdene”. These are city dumpsites (Rezekne and Ludza). Significantly less polluted leachate is found in the dumpsites “Zelceva” and “Mostovaja”. This is valid for all analyzed parameters – COD, conductivity, Ntot., NH4 + and Cl.
Antibacterial and anti-viral effects of silver nanoparticles in medicine against COVID-19—a review
(2020)
Teirumnieks, Edmunds
;
Ivaylo Balchev
;
Risham Singh Ghalot
;
Lazov, Lyubomir
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
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)
Lazov, Lyubomir
;
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.
Artificial Neural Networks: What Can They Learn about Color Laser Marking?
(2018)
Pavels Cacivkins
;
Lazov, Lyubomir
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Teirumnieks, Edmunds
;
Martins Sperga
;
Ingus Dilevka
;
Artis Vitins
Color laser marking paves the way for many useful applications in modern industry - traceability, anticounterfeiting, etc. Laser marking of materials is an inherently difficult problem with no clear functional relationship between many technological parameters on the input and the results of processing on the output. Some processes cannot be well defined without the use of examples. In this paper we discuss the novel method of training artificial neural networks using real experimental color laser marking data for prediction of results. We conclude the paper by discussing the other potential applications of proposed solution in the field of laser materials processing.
Scopus© Citations 1
CARBON DIOXIDE (CO2) LASER MARKING PROCESS PARAMETER IMPACT ON MARK QUALITY OF POLIVINILCHLORIDE (PVC) MATERIAL
(2017-04-19)
Riekstiņš, Jānis
;
Sivenkovs, Artūrs
;
Lazov, Lyubomir
;
Narica, Pāvels
Laser technologies nowadays are widely used in material processing. CO2 laser systems in most cases are used in metallic material manufacturing and processing, taking not so big part in processing of plastic materials. This research is dedicated to find advantages or disadvantages and ways to use CO2 laser systems in plastic material processing, by taking PVC material as sample for experiments. PVC plastics is widely used in manufacturing of electrical installation details and devices, it is durable, relatively light, and cheap material. To provide application of various symbols, on the surface of plastic materials, can be used laser systems, which in long term can be more efficient than conventional marking methods. The aim of this work is to find if CO2 laser is appropriate for marking PVC material and to relate the mark quality parameters and the marking process parameters. The research was conducted in the period of time from March 2017 till April 2017, in the Rēzekne Academy of Technology, Physical process and laser technology research center.
CARBON FIBER AND PLANT FIBER COMPOSITE TECHNOLOGY DEVELOPMENT IN HIGH STRENGH PARTS
(2017)
Pīgožnis, Kārlis
;
Teirumnieks, Edmunds
Natural abundance, low density, high strength per unit weight, and biodegradability of natural materials, specifically natural fibres, render them attractive for other reinforcements. In order to clarify the effect of natural fibers as reinforcments upon the tensile strength of polyacrylonitrile (PAN)-based carbon fibres, experimental as well as theoretical studies have been performed. A new material developing has been made in combining different fiber materials and testing them for strengh.
CLEANED WATER QUALITY IN THE EXPERIMENTAL CIRCUIT LABORATORY
(2016)
Grisone, Agnese
;
Teirumnieks, Edmunds
For the moment there is no problem, because the clean water complies with the following requirements. But it is the nature of the mechanical problems, where technical and cleaned water in the production process increased conductivity indicators and the pH value is less than the soft water after legislative dossier. Materials and methods are described in the clean water sampling physical – chemical testing, as well as describes the methods used. And you are prompted to create the electricity supply system, which, in addition to the accidental or unplanned power off position. It will depend on the results of a number of indicators. You can view a version of the technology, if not improving, the ability to create an automatic power supply system.
COLOR MARKING OF STAINLESS STEEL AND TITANIUM WITH THE LASER OXIDATION METHOD
(2023)
Petar Tsvyatkov
;
Emil Yankov
;
Lazov, Lyubomir
;
Teirumnieks, Edmunds
;
Teirumnieka, Ērika
Marking of metal products is essential in many industrial processes. It is mandatory for the finished products according to regulations of the European and world legislation. Traditional marking usually creates contrasting symbols that can easily be erased and forged.In recent years, a new method for product identification has appeared - color marking. One of the advantages of this method is that it is difficult to counterfeit. This article aims to present the progress of color marking technology on two types of materials. Three groups of factors have been analyzed: the laser source; the technological process; material properties. Their role in obtaining a specific color marking on Ti and AISI 304 is shown. The results are presented in tables. Each color can be repeated only with strict observance of the three groups of factors.
COMPUTER CONTROL THE ACCURACY OF THE PARTS PROCESSED ON CNC MACHINE TOOLS BASED ON STATISTICAL PROCESS CONTROL
(2017)
Angel Lengerov
;
Galina Nikolcheva
;
Julieta Kaleycheva
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Lazov, Lyubomir
Statistical process control (SPC) can help manufacturers improve the quality of their products. This paper describes a relatively simple and effective method and algorithm to adjust the accuracy of parts produced on CNC machine tools using the methods of statistical process control. Examined the possibilities of the proposed method by computer simulation of the process. By using the proposed algorithm scattering of size is placed in the middle of the tolerance zone. Various variants carrying out the method are proposed adequate on the machining time during processing details in the sample. This can optimize the total time for processing of the batch.
COMSOL SIMULATION OF LASER WELDING OF ALUMINUM
(2021)
Ivaylo Balchev
;
Lazov, Lyubomir
;
Nikolaj Angelov
;
Teirumnieka, Ērika
This research includes a Comsol Mutiphysics model describing the temperature distribution on aluminum during the laser conductivity welding process. The influence of laser power and speed on the welding process is discussed and compared with experiments. Numerical simulations of laser welding process have been performed to determine the temperature fields of laser impact to samples of aluminum. Numerical calculations are made for fiber laser. The plots of the temperature dependence on the surface and in the depth of aluminum samples on the velocity are analyzed for several power densities for this laser.
Determination constants of 4-element reological model with rebound resilience method
(2017)
Martinovs, Andris
;
Svetlana Polukoshko
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Elvijs Apeinans
;
Zaicevs, Edgars
In this paper an express-method and equipment for experimental determination of the 4-element rheological model constants (2 elastic modulus, 2 viscosity coefficients) for elastomers are developed. The method is based on rebound of falling hammer against an elastomer material. A mathematical model for describing this collision is elaborated and an algorithm for determination of the constants of the model was developed and realized in Matlab software. Time necessary for determination of the constants is until 5 minutes. It gives an opportunity to significantly accelerate the design and production process of elastomer-metal vibration isolator prototypes with defined parameters of stiffness and damping. The method allows to trace displacement, velocity and acceleration of the metal parts of the shock absorber throughout the collision; this may be realized with Matlab or an analogical program of numerical integration. For forecasting of the mechanical properties of the shock absorber during a long period (considering the aging of elastomer) it is necessary to know the rheological model parameter dependence on time, temperature, energy input and other factors; the proposed method allows to significantly accelerate these experimental studies.
Scopus© Citations 2
Distribution of iron and iron compounds in the Kemeri - Jaunkemeri occurence of sulphide water
(2015)
Janis Prols
;
Teirumnieka, Ērika
;
Teirumnieks, Edmunds
Iron concentrations, distribution and migration forms, depending on pH and oxidation – reduction potential, were analyzed in case of the Kemeri-Jaunkemeri occurrence (area about 240 km2) of sulphide containing water (maximal sulphides concentration – 74 mg/l), located in Latvia. Iron content was investigated in 457 wells located within all area of occurrence. Those wells were installed to two aquifers: the Quarternary multi-aquifer and Salaspils aquifer, where occurrence of sulphide containing groundwater is distributed. All groundwater of occurrence is classified in four types depending on oxygen, sulphides and organic matter content in the groundwater. Modeling of groundwater migration forms was carried out, and it is stated that iron migrates basically as Fe2 in oxygen and suphides non-containing water. Migration forms are influenced by concentration of organic matter in the aquifer. The portion of Fe2 migrating in a form of free decreases due to formation of complexes with fulvic and humic acids, which can reach 36.5% of all migration forms. Iron migrates as Fe(OH)3 in oxygen containing water (more than 99% of determined forms). Presence of iron is ascertained also in sulphides containing water, where iron migrates basically as (98.8% of determined forms). This occurs due to formation of complexes with sulphydes – FeHS- and Fe(HS)2o.
EAST LATGALE SAA PROJECT
(2001)
Teirumnieks, Edmunds
;
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.
Effect of Atmospheric Pollution on Air Ion Concentration
(2017)
Andris Skromulis
;
Juris Breidaks
;
Teirumnieks, Edmunds
In the article, the possible impact of atmospheric pollution on air ions of various classes were analysed by the method of statistical analysis. The raw data summarized and analysed in the article were obtained within one year period in a monitoring station, by measuring CO, NO, NO2, SO2, O3, PM10, temperature, relative humidity, wind speed and direction, as well as spectrum of air ion concentrations, where ion size varied between 0.75 to 36.6 nm. With a help of stepwise regression, the significant parameters were selected and mathematic equations were obtained in order to explain concentrations of positive and negative small, intermediate and heavy air ions with the selected parameters.
Scopus© Citations 11
Effect of Laser Marking Speed, Power and Pitch on Hardness and Roughness of Aisi 304l
(2023)
Lazov, Lyubomir
;
Teirumnieks, Edmunds
;
Emil Yankov
;
Nikolay Angelov
;
Adijāns, Imants
;
Antons, Pacejs
In this study, an experiment was conducted to change the technological properties of the surface by infra-red laser marking. The influence of power, speed and raster step was investigated. These parameters during laser marking of AISI 304L steel have a significant change on the microhardness and surface roughness. It was found that high stiffness is achieved at higher powers and small pitch. An analysis of the results showed that as the raster step increases, the roughness of the marked sample decreases. The influence of linear energy density and overlap factor on the process was also investigated. The microhardness of the treated surfaces increases with an increase in the linear energy density and the overlap coefficient, and in the first case the dependence is almost linear, and in the second - non-linear.
Environment Pollution With Oil Products and Review of Possibilities for Collection Thereof
(2011)
Viktors Mironovs
;
Teirumnieks, Edmunds
;
Juris Treijs
The largest global pollution nowadays gives oil and oil products. This contamination poses a danger to the environment and aquatic eco-systems. Not only seas but also small water bodies and watercourses, as well as coastal areas, soil and groundwater are contaminated with oil products. Contamination results in destruction of some plants or animals, but in events of high oil contamination also of the entire ecosystem. Latvia has inherited the oil pollution from both the Soviet Union large-scale industry and its military facilities, as well as at present the oil products are getting into environment from petrol stations, accidents, and from the cross-border pollution. In many cases of oil spills, people are trying to collect them in order to have no impact on the environment, but unfortunately very often, even in most cases this does not occur. Financial resources, as well as the lack of appropriate technologies or restricted possibilities for their application are the limiting factors. The article deals with the traditional methods of oil collection in water and also describes options for decontamination of polluted soil from the oil products. A brief insight is provided into application of ferromagnetic sorbents, which is a new method for collection of oil and oil products.
Scopus© Citations 2

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