Browsing by Department "Mehatronikas un mašīnbūves tehnoloģiju laboratorija / Mechatronics and Mechanical Engineering Technology Lab"
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- Publication3D MATHEMATICAL MODEL CHARACTERIZING THE DYNAMICS OF THE TEMPERATURE FIELD OF A WALL STRUCTURE WITH A DOUBLE-SIDED FACING FROM A SAPROPEL-HEMP COMPOSITE MATERIAL(2021)
;Sharif E. Guseynov ;Janis Rimshans ;Jekaterina V. Aleksejeva ;Aleksandrs BereznojsIn this paper, a 3D mathematical model is proposed to determine the dynamics of the temperature field in a three-layer composite sapropel-hemp slab. The proposed model consists of a system of three initial-boundary value problems with respect to the temperature function for each layer, respectively, and one initial-boundary value problem with respect to the unknown velocity of heat propagation along the thickness dimension of the composite sapropel-hemp slab. - Publication3D SCANNERS. DIVERSITY AND OPERATING PRINCIPLES(2017)
;Aksjonovs, Artēmijs; Martinovs, AndrisThe 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. - PublicationA Method For Determination Of Specific Electrical Resistance Of Steel And Nano-Coating Sputtered On It(2015)
; ;Josef Timmerberg ;Konstantins Savkovs ;Aleksandrs UrbahsPaul BeckmannThe paper describes methods developed to determine specific electrical conductivity and relative magnetic permeability of cylindrical steel items and nano-coatings deposited on them by sputtering. Research enables development of a new method for determination of thickness of vacuum deposited nano- coating that is based on application of skin effect. - PublicationADHESION TEST ON DIFFERENT WORK SURFACES(2023)
;Justs Batņa ;Rihards MisjunsŠī publikācija parāda adhēzijas rezultātus, veicot to uz vairākām darba virsmām. Tika izmantotas 6 darba virsmas un veikti 18 adhēzijas testi, uz katras darba virsmas - 3 testi. Testu veikšanai uz darba virsmām tika printēti 20x20x10mm četrstūri no PETG plastmasas, izmantojot 3D printeri Ender 3 Pro. Adhēzijas testi veikti ar Zwick/Roell Z150 elektromehāniskās stiepes un kompresijas pārbaudes iekārtu. - PublicationAGING, FATIGUE AND DURABILITY OF RUBBER VIBRATION ISOLATION ELEMENTS(2017)
;Svetlana Polukoshko; Svetlana SokolovaThis paper deal with shock and vibration insulators, which usually are performed from the elastomeric (rubber-like) materials. Elastomeric materials give many engineering advantages due to their capability of absorbing input energy much better than engineering materials, high elasticity, good dynamic properties, low volume compressibility, a linear relationship between stress and strain up to strain of 15% ÷ 20%, resistance to aggressive environmental factors. Elastomeric materials are widely used in machine building, shipbuilding, civil engineering, aviation and aerospace as compensation devices, vibration dampers, shock absorbers. Laminated elastomers, consisting of interleaved thin layers of elastomer and rigid reinforcing layers are also successfully used as bearing, joints, dampers, compensating devices, shock-absorbers. Such structures have many advantages: ability to endure high stress (>200 MPa), ease of maintenance, non- necessity for lubrication, vibration and noise reduction, ability to work in a very dirty, dusty, abrasive environment. The disadvantage of elastomeric material are aging, i.e. changing its properties over time. In this paper the influence of aging of elastomeric materials on the damping properties of shock absorbers is considered based on the mechanical models of elastomers - Maxwell and Burgers modes. Fatigue endurance, i.e. the ability to withstand mechanical actions for a long time is studied based on experiments on dynamic shear with laminated rubber-metal structures. The experiments show that such structures have a very high fatigue life - up to 100 million cycles.Scopus© Citations 5 - PublicationAir ionizer and indoor plants interaction impact on ion concentration(2017)
;Natalija SiņicinaThe plants emit different types of volatile organic compounds (Bio VOC’s) and can improve air quality: they effectively remove organic pollutions and reduce the number of microorganisms in the air by releasing phytoncides. The lack of negative ions in the air can cause deterioration of the health of humans breathing it. At the same time, an air saturated with negative ions can improve the state of health and provide a comfortable environment. In this article, the influence of the plants (Cupressus macrocarpa) on the number of ions is proved, based on a series of experiments performed with applying high-voltage pulses (air ionizer). This work is devoted to the elaboration of the mathematical relationship between the air ions concentration and the factors influencing it. For this purpose an experimental stand was made, consisting of two equal compartments: one contained the plants while another one was used as a control without plants. It was concluded that the plants, in general, are able to stabilize the ion concentration and to reduce its fluctuations. The plants help to increase the concentration of negative ions and to decrease the concentration of positive ones. - PublicationAmount of Air Ions Depending on Indoor Plant Activity(2015)
;Natālija Siņicina ;Andris SkromulisLiterature sources and earlier researches state that plants may be able to produce a variety of air ions, including negative light ions. In this article, the regularity of influence of plants on the number of ions in the room is being proved, basing on a series of experiments performed with the following plants: Spathiphyllum, Scindapsus, Strobilanthes, Chlorophytum and Pinus mugo. It was concluded that plants, in general, are able to stabilize the indoor ion concentration and reduce its fluctuations. The plants help to increase the concentrations of negative ions and decrease the concentration of positive ones, however the optimal and “healthy” ion concentration was not reached. Plants without artificial illumination work more as ion reducers, not producers.</span></p>Scopus© Citations 5 - PublicationAutonomous Vehicles and Mechatronics Education(2020)
;Gilberto Marzano; Svetlana UscaAutomotive mechatronics involves the multidisciplinary integration of automotive mechanical and electronic systems. As such, automotive mechatronics education integrates knowledge and competences across automotive-specific mechanics, electronics, communication, advanced control, and modeling. Over the last few years, the subject of autonomous vehicles has been attracting significant attention from researchers, as well as interest from the media and the public at large. It encompasses a myriad of new applications, ranging from driverless cars to airborne surveillance of sensitive areas. Designing solutions for autonomous vehicles requires the integration of hardware and software components, as well as interaction with cloud-based servers. This paper focuses on autonomous/unmanned ground vehicles within the scope of a mechatronics curriculum. It has been proposes an educational model for autonomous vehicles for inclusion in the new mechatronics curriculum of NewMetro, an EU funded project that aims to develop an innovative European framework of competences for mechatronics education. - PublicationBLASTING MACHINE(2023)
;Gatis TutinsSkrotēšanas iekārtas atrodas katrā lielā metālapstrādes uzņēmumā, tās nepieciešamas, lai efektīvi varētu attīrīt tērauda detaļas, un pēc attīrīšanas kvalitatīvi veikt krāsošanas darbus. Skrotēšanas iekārta ievērojami uzlabo detaļu apstrādi un to kvalitāti. Tomēr reti kurš aizdomājas par to, kā optimizēt noskrotēto detaļu kvalitātes uzraudzību, īpaši ziemā kad kļūst vēsāks un ir nepieciešams uzraudzīt skrotēšanas telpas temperatūru, mitrumu un rasaspunktu. Tāpēc šī izpēte ir vērsta uz to, lai noskaidrotu cik liela skrotēšanas ietekme ir uz materiālu, kādi ir skrotēšanas veidi un tehnoloģijas, un kādu ietekmi uz noskrotēto materiālu atstāj temperatūras svārstības skrotēšanas iekārtas telpā. Tiks aprakstīts kādus uzlabojumus varētu veikt skrotēšanas iekārtai, kādēļ šie uzlabojumi ir nepieciešami un ar kādām komponentēm uzlabojumi tiktu panākti. - PublicationCARBON FIBER AND PLANT FIBER COMPOSITE TECHNOLOGY DEVELOPMENT IN HIGH STRENGH PARTS(2017)
; 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. - PublicationDAŽI DIELEKTRISKĀS CAURLAIDĪBAS PĒTĪJUMU ASPEKTI GUMIJAS MĀKSLĪGĀS NOVECOŠANAS PROCESOS(1999)Gumija ekspluatācijas laikā ir pakļauta ilgstošai dabiskai novecošanai, kuras rezultātā izmainās gumijas struktūra, pasliktinās elastīgās īpašības un mehāniskā izturība. Konstruktoram ir nepieciešams zināt, cik ilgi konkrētais gumijas izstrādājums dotajos apstākļos spēs kalpot. To var prognozēt uz paātrināto eksperimentu pamata. Šie eksperimenti ir saistīti ar gumijas mākslīgo novecošanu, kad pētāmajam paraugam papildus tiek pievadīta enerģija, iedarbojoties uz to ar temperatūras lauku, radiāciju, ķīmiski aktīvām vielām, vibrācijām vai kā citādi. Mākslīgajā novecošanā straujāk izmainās gumiju raksturojošie parametri un īsākā laikā sasniedz savas kritiskās vērtības, pie kurām gumijas izstrādājums vairs nav lietojams. Dotajā darbā kā viens no šādiem parametriem ir izvēlēta dielektriskā caurlaidība, mākslīgā novecošana tiek veikta paaugstinātā temperatūrā.
- PublicationDESCRIPTIVE MODEL OF SLIDING FRICTION PROCESSES(2009)
; Vladimir GoncaPaper analyses the sliding friction coefficient of rubber on concrete, timber and ceramic tile surfaces depending on the weight of the sliding object and contact surface area. It has been established that increase in the weight of the object makes sliding friction coefficient to grow. In the case of increase in size of contact area, sliding friction coefficient between rubber and concrete also increases, but it decreases between rubber- timber and rubber- tile. The mathematical model for description of sliding friction process has been developed which can be used to determine optimal surface area and a pattern as well as optimal weight of the sliding object in order to provide sufficient sliding friction. Model has five independent constants. It includes the contact surface area, the weight and the velocity of the sliding object, sliding friction coefficient, temperature and time. - PublicationDetermination constants of 4-element reological model with rebound resilience method(2017)
; ;Svetlana Polukoshko ;Elvijs ApeinansIn 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 - PublicationDoes the energy transfer from Ar(1s) atoms to N2 lead to dissociation?(2020)
;Claus‐Peter Klages; ;Lars BröckerDetlef LoffhagenDielectric‐barrier discharges (DBDs) in Ar–N2 mixtures, with N2 fractions in 0.1–1% range, would be attractive alternatives to DBDs in pure N2 if energy‐transfer reactions between Ar(1s) atoms and N2 molecules were an efficient source of N atoms. Attempts to functionalize polyolefins in flowing postdischarges fed by such DBDs, as well as the search for the First Positive System in the emission spectrum, however, failed. Evidently, the energy‐transfer reactions do not produce N atoms. For Ar(1s3) and Ar(1s5) metastable states, this fact has already been reported in the literature. For Ar(1s2) and Ar(1s4) resonant states, a quantitative argument is derived in this paper: energy transfer from Ar(1s) atoms to N2 molecules is not an efficient source of N atoms.Scopus© Citations 3 - PublicationEFFECT OF HEAT TREATMENT ON ELECTRICAL AND MECHANICAL PROPERTIES OF THE SOLID SAPROPEL(2017)
; ; ;Rene Castro ;Vladimir Solovyev ;Josef Timmerberg ;Alexander Cvetkov ;Sergey Gango ;Angelika Borkenstein ;Paul Beckmann ;Helmut Schütte ;Nikolai PuchkovSergey TrifonovIn this work changes of electrical and mechanical properties (hardness) of the solid sapropel after its heat treatment were researched. Changes of real and imaginary parts of dielectric permittivity, dielectric losses and specific electrical resistance depending on electrical field frequency in the range 0.01Hz- 1MHz were observed. Temperature dependences of AC (at 1 kHz) and DC electrical conductivity were studied. Chemical sample composition, IR spectra and structure of the solid sapropel were investigated. Heat treatment has a noticeable effect on the electrical characteristics of solid sapropel due to the strong influence of water on the charge transfer in this complex material. Charge transfer occurs predominantly due to ion migration and demonstrates strong dependence upon hydration - dehydration processes. After the heat treatment of the solid sapropel at the temperature of 1000C its hardness doesn’t change. If the sample of the solid sapropel is subjected to 20 min heat treatment at the temperature of 1500C, its hardness decreases by 5.4%, the number of C=C bonds decreases by 6.3±0.1%, the number of C=N bonds decreases by 2.2±0.1%, the number of C-C bonds decreases by 1,7±0.1%, the number of C-H bonds increases by 18.5±0.3%. It shows that in the temperature range 100-1500C destructive processes of the solid sapropel start, although visually (with optical microscope and with SEM) changes of structure are impossible to observe yet.Scopus© Citations 2 - PublicationEstimation of stress and displacement increase caused by heat generation in rubber vibration absorber(2020)
;Svetlana Polukoshko; Vladimirs GoncaRubber and rubber-like materials (elastomers) are widely used for anti-vibration mounts and shock absorbers for vehicles, machinery, building structures due to their specific properties: ability to absorb vibration and shock loads, low elastic modulus, high mechanical strength, high elongation at brake, reversible elastic deformation. Rubber is a material that is capable of recovering from large deformations quickly and forcibly, which is suitable for work under cyclic loading. During deformation elastomeric materials absorb in an irreversible way part of the energy, causing this deformation. The energy absorbed during each cycle heats the deformed rubber element and dissipates in media. Heat generation in rubber causes additional stresses and deformations which are poorly known, and they are a subject of our study. In the presented paper the work of a rubber anti-vibration mount in the form of a straight circular cylinder under action of cyclic loading is studied. Poisson’s ratio of the rubber material is μ = 0.5, the weight of the mount is not taken into account. Temperature field is assumed known based on the previous work (it depends on the frequency and amplitude of vibration, heat conductivity and heat capacity of the material, etc.). The stress-strain state analysis was carried out based on the Reissner variational principle. Analytical dependences for temperature additions to stresses and displacements are derived that allows estimating stiffness of the anti-vibration mount and its increase as a result of self-heating. Obtained results may be useful for proper design of anti-vibration mounts allowing changing geometrical dimensions in order to reach the required temperature field. - PublicationExperimental justification for sapropel and hemp shives use as thermal insulations in Latvia(2015)
; ;Maris SinkaGenadijs SahmenkoFossil energy resources in Latvia are imported from other countries, but at the same time, our country is rich in renewable energy resources and other raw materials, which are used very little. In the study it is proposed to create a thermal insulation material from hemp shives grown in Latvia as a filler material and lake sediment - sapropel as a binding agent. Both of the following materials are organic, renewable and locally available. Laboratory experiments show that ecological and complying with modern requirements thermal insulation material can be obtained from local, renewable raw materials: sapropel and hemp shives.Scopus© Citations 8 - PublicationEXPERIMENTAL STUDYING OF MECHANICAL-AND- PHYSICAL PROPERTIES OF RUBBER DURING AGEING(2019)
;Svetlana Polukoshko; Elastomeric materials, both natural rubber and synthetic, are widely used in industry and civil engineering, due to their unique properties: high elasticity, low volume compressibility, capability to absorb and dissipate input energy, a linear relationship between stress and strain up to strain of 15% ÷ 20%, resistance to aggressive environmental factors. Different kind of compensation devices, vibration dampers, shock absorbers are fabricated from rubber materials.At the same time the elastomeric materials nonreversible change their properties over time, this disadvantage is called ageing.In given paper the results of experimental studying of the influence of aging on the physical-and-mechanical properties of polyurethane rubber is presented. The samples of cylindrical form were prepared from soft flexible polyurethane rubber Xenias PX30 and subjected to the artificial ageing. Accelerated aging of samples was fulfilled in accordance with European standard ISO 188:2011 (Rubber, vulcanized or thermoplastic - Accelerated ageing and heat resistance tests).The changing of volume, Shore A hardness, elastic rebound coefficient and static elasticity modulus under compression were investigated. Experiments showed the volume decrease, hardness shore increasing, elastic rebound increase and compression modulus under static loading increasing. This data are necessary for correct designing of the compensation devices to provide their working properties during all service life. - PublicationIMPACT OF LASER ON MICROORGANISMS IN THE DIGESTATE(2017)
; ; ; Samanta Marija MisiņaAt the biogas plant total of 40 digestate samples have been collected and investigated. The microbiological composition of digestate has been analysed before and after laser processing with wavelength λ 445 nm with power 2 - 4 W. Salmonella spp. has not been stated in any of the samples, Escherichia coli and Enterococcus spp. amount does not correspond Eiropean Union regulation R142/2011 requirements in any of the investigated samples; Staphylococcus aureus has been stated in 24 samples out of 40. By decreasing laser scanning speed and increasing power, the total number of microorganism colonies in digestate has decreased. - PublicationImpact of Microclimate and Indoor Plants on Air Ion Concentration(2013)
;Natalia Sinicina ;Andris SkromulisSaturation of air ions is essentially important for all living beings, especially for human health. Existing sanitary norms provide that concentration of small ions has to be in range of 400-50000 ions cm-3 and unipolarity coefficient 0.4 ≤ K ≤ 1.0. Many species of indoor plants emit organic volatile compounds and air ions, therefore they could be used for improving the quality of indoor air. The results show that ionization level of indoor air is significantly insufficient and selected species of indoor plants are not able to improve it. They serve rather as supplementary surfaces for ion absorption. Possible interaction between microclimate, ion concentration and indoor plants in different times of the day is analyzed.Scopus© Citations 6
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