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21دورية أكاديمية
المؤلفون: Wang, Yong, Wang, Xiaolin, Zhang, Zilong, Li, Yu, Liu, Houlin, Zhang, Xiang, Hočevar, Marko
المصدر: Strojniški vestnik, vol. 67, no. 3, pp. 75-87, 2021. ; ISSN: 0039-2480
مصطلحات موضوعية: multiphase flow, impact force, cleaning performance, optimization, pulsed jet, večfazni tok, udarna sila, curek, učinek čiščenja, optimizacija, metoda odzivnih ploskev, info:eu-repo/classification/udc/532.5:519.61(045)
الوصف: A self-excited pulsed air-water jet (SEPAWJ) offers many advantages over other jets and has a large number of practical and industrial applications. In order to take better advantage of the SEPAWJ, response surface methodology (RSM) models were established with the experimental impact force characteristics as the dependent variable and three key nozzle parameters as the independent variable. Single and coupling factor effects of these three parameters (oscillation chamber length, oscillation chamber height, and diameter of the downstream nozzle) on performance of nozzle are analysed, and the structural parameters of optimum performance are calculated using RSM models. The external flow field, impact force and cleaning performance of SEPAWJ before and after optimization are analysed and compared experimentally. It is found that the significance levels of established average impact force and impact force amplitude RSM models are lower than 0.05, and their error ratios between calculation and experiment under the optimum construction are both less than 5 %, which confirms their considerable reliability. Meanwhile, the final large water mass of optimized SEPAWJ is formed much earlier, and is more intensive and more concentrated. Compared with the original SEPAWJ nozzle, the impact force and impact force amplitude of optimized SEPAWJ nozzle are increased by 52.00 % and 38.26 %, respectively. In addition, the cleaned area ratio of nozzle before and after optimization is 76 % and 100 % at 50 seconds, respectively, with an increase of 22.4 %.
وصف الملف: application/pdf; text/url
العلاقة: info:eu-repo/grantAgreement/Drugi/National Natural Science Foundation of China/51779106; info:eu-repo/grantAgreement/Drugi/National Natural Science Foundation of China/51979126; info:eu-repo/grantAgreement/Drugi/Priority Academic Programme Development of Jiangsu Higher Education Institutions, Ministry of Education Xihua University/szjj2016-068; info:eu-repo/grantAgreement/ARRS//P2-0401; https://repozitorij.uni-lj.si/IzpisGradiva.php?id=127809Test; https://repozitorij.uni-lj.si/Dokument.php?id=144352&dnTest=; https://repozitorij.uni-lj.si/Dokument.php?id=144350&dnTest=; https://plus.si.cobiss.net/opac7/bib/58616323?lang=slTest
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22دورية أكاديمية
المؤلفون: Rak, Gašper, Hočevar, Marko, Steinman, Franci
المصدر: Journal of Hydrology and Hydromechanics, vol. 67, no. 2, pp. 163-170, 2019. ; ISSN: 0042-790X
مصطلحات موضوعية: junction, hydraulic experimentation, standing wave, supercritical flow, flow patterns, gradbeništvo, vodarstvo, hidrotehnika, sotočje, hidravlične raziskave, stoječe valovanje, deroči tok, vzorci vodnega toka, info:eu-repo/classification/udc/621.22-821:626/627
الوصف: The complexity of flow conditions at junctions amplifies significantly with supercritical flow. It is a pronounced three-dimensional two-phased flow phenomenon, where standing waves with non-stationary water surface are formed. To analyse the hydrodynamic conditions at an asymmetric right-angled junction with incoming supercritical flows at Froude numbers between 2 and 12, an experimental approach was used. For a phenomenological determination of the relations between the integral parameters of incoming flows and the characteristics of standing waves at the junction area, water surface topographies for 168 scenarios at the junction were measured using non-intrusive measurement techniques. The new, phenomenologically derived equations allow for determination of location, height and extent of the main standing waves at the junction. Research results give important information on the processes and their magnitude for engineering applications.
وصف الملف: application/pdf; text/url
العلاقة: https://repozitorij.uni-lj.si/IzpisGradiva.php?id=126365Test; https://repozitorij.uni-lj.si/Dokument.php?id=142288&dnTest=; https://repozitorij.uni-lj.si/Dokument.php?id=142287&dnTest=; https://plus.si.cobiss.net/opac7/bib/8671841?lang=slTest
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23دورية أكاديمية
المؤلفون: Pipp, Peter, Hočevar, Marko, Dular, Matevž
المصدر: Applied sciences, vol. 11, no. 6, pp. 1-12, 2021. ; ISSN: 2076-3417
مصطلحات موضوعية: cavitation, Kelvin-Helmholtz instability, microchannel, numerical simulation, kavitacija, Kelvin-Helmholtzova nestabilnost, mikro kanali, numerične simulacije, info:eu-repo/classification/udc/519.876.5:532.528(045)
الوصف: Recently the development of Kelvin-Helmholtz instability in cavitating flow in Venturi microchannels was discovered. Its importance is not negligible, as it destabilizes the shear layer and promotes instabilities and turbulent eddies formation in the vapor region, having low density and momentum. In the present paper, we give a very brief summary of the experimental findings and in the following, we use a computational fluid dynamics (CFD) study to peek deeper into the onset of the Kelvin-Helmholtz instability and its effect on the dynamics of the cavitation cloud shedding. Finally, it is shown that Kelvin-Helmholtz instability is beside the re-entrant jet and the condensation shock wave the third mechanism of cavitation cloud shedding in Venturi microchannels. The shedding process is quasi-periodic.
وصف الملف: application/pdf; text/url
العلاقة: info:eu-repo/grantAgreement/EC/H2020/771567; info:eu-repo/grantAgreement/ARRS//P2-0401; https://repozitorij.uni-lj.si/IzpisGradiva.php?id=125677Test; https://repozitorij.uni-lj.si/Dokument.php?id=141507&dnTest=; https://repozitorij.uni-lj.si/Dokument.php?id=141506&dnTest=; https://plus.si.cobiss.net/opac7/bib/56979971?lang=slTest
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24دورية أكاديمية
المؤلفون: Podnar, Andrej, Hočevar, Marko, Novak, Lovrenc, Dular, Matevž
المصدر: Applied sciences, vol. 11, no. 6, pp. 1-18, 2021. ; ISSN: 2076-3417
مصطلحات موضوعية: hydrofoil, bulb turbine, bulb turbine runner, cavitation, flow visualization, cavitation tunnel, regression model, hidrodinamski profil, cevna turbina s hruško, kavitacija, vizualizacija toka, kavitacijski model, regresijski model, info:eu-repo/classification/udc/519.8:532.528(045)
الوصف: The influence of a bulb runner blade hydrofoil shape on flow characteristics around the blade was studied. Experimental work was performed on a bulb turbine measuring station and a single hydrofoil in a cavitating tunnel. In the cavitation tunnel, flow visualization was performed on the hydrofoil's suction side. Cavitation structures were observed for several cavitation numbers. Cavitation was less intense on the modified hydrofoil than on the original hydrofoil, delaying the cavitation onset by several tenths in cavitation number. The results of the visualization in the cavitation tunnel show that modifying the existing hydrofoil design parameters played a key role in reducing the cavitation inception and development, as well as the size of the cavitation structures. A regression model was produced for cavitation cloud length. The results of the regression model show that cavitation length is dependent on Reynolds's number and the cavitation number. The coefficients of determination for both the existing and modified hydrofoils were reasonably high, with R2 values above 0.95. The results of the cavitation length regression model also confirm that the modified hydrofoil exhibits improved the cavitation properties.
وصف الملف: application/pdf; text/url
العلاقة: info:eu-repo/grantAgreement/ARRS//P2-0401; https://repozitorij.uni-lj.si/IzpisGradiva.php?id=125678Test; https://repozitorij.uni-lj.si/Dokument.php?id=141509&dnTest=; https://repozitorij.uni-lj.si/Dokument.php?id=141508&dnTest=; https://plus.si.cobiss.net/opac7/bib/56988419?lang=slTest
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25دورية أكاديمية
المؤلفون: Hočevar, Marko, Novak, Lovrenc, Rak, Gašper
المصدر: Acta hydrotechnica, vol. 32, no. 56, pp. 35-43, 2019. ; ISSN: 1581-0267
مصطلحات موضوعية: energy storage, EUSALP region, photovoltaics, wind, pumped storage hydropower plants, shranjevanje energije, EUSALP, fotovoltaika, veter, črpalno akumulacijske hidroelektrarne, info:eu-repo/classification/udc/621.311.243:627.8.09(234.3)(4)
الوصف: In this paper we discuss energy storage requirements for EUSALP region in Europe. EUSALP is an Alpine region that includes the entirety Switzerland, Austria, Slovenia, and Lichtenstein, as well as parts of France, Germany, and Italy. A model is presented that facilitates the estimation of the required technical amounts of energy storage and installed power of pumped storage hydropower plants. The aim of the model is to estimate the requirements of energy storage to assist in setting guidelines for stable and reliable future electric energy supply in the EUSALP region. The model is based on currently known patterns of energy consumption and generation and available information on the future increase of renewable electric generation capacity, energy consumption, and the introduction of electromobility within all EUSALP regions. The hourly balance of generation, demand, and storage within a selected future year is assumed. The results are presented such that a mix of scenarios is addressed. Among them are installed generation capacity, installed pumped hydro storage power, selection of photovoltaic and wind electric energy generation ratio, the charging of a selected percentage of electric cars, flexible run-of-river hydro electric energy generation, import/export, generation by nuclear and backup fossil fuel sources, and a selection of disturbances. Results show that energy storage capacities must be increased by a large margin regardless of the choice of demand site management strategies or flexible electric car charging. Around a requisite 10-fold increase in pumped storage hydropower capacity is estimated, while the estimated increase in required energy storage is even higher. Daily and seasonal variations are also discussed. Further, the amount of surplus electric energy generation is presented and discussed. ; Članek prikazuje potrebe po shranjevanju električne energije za območje regije EUSALP v Evropi. EUSALP je alpska regija, ki vključuje celotno Švico, Avstrijo, Slovenijo, Lihtenštajn in dele Francije, ...
وصف الملف: application/pdf; text/url
العلاقة: info:eu-repo/semantics/altIdentifier/urn/URN:NBN:SI:doc-3DEKSBUK; https://repozitorij.uni-lj.si/IzpisGradiva.php?id=125687Test; https://repozitorij.uni-lj.si/Dokument.php?id=141534&dnTest=; https://repozitorij.uni-lj.si/Dokument.php?id=141533&dnTest=; https://plus.si.cobiss.net/opac7/bib/8908897?lang=slTest
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26دورية أكاديمية
المؤلفون: Munih, Jernej, Hočevar, Marko, Petrič, Klemen, Dular, Matevž
المصدر: Engineering applications of computational fluid mechanics, vol. 14, no. 1, pp. 1023-1034, 2020. ; ISSN: 1994-2060
مصطلحات موضوعية: volumetric pump, computation fluid dynamics, volumetric efficiency, tumbling multi-chamber, gear pump, CFD, volumetric, experimental, volumetrična črpalka, numerično modeliranje tekočin, volumetrični izkoristek, zobniške črpalke, volumetrično, eksperimentalno, info:eu-repo/classification/udc/519.876.5:621.6(045)
الوصف: Tumbling Multi-Chamber (TMC) gear pump is a generally unknown type of hydraulic device, which features a unique three-dimensional shape of the gears. The main benefits of such design over the conventional gear pumps are self-adapting tightness of the pump parts, the possibility to mold the parts from a polymer material and high volumetric efficiency, considering the simplicity of the design. The specific working principle of TMC pumps requires a slightly different approach to the numeric modeling and analysis process compared to the conventional gear pump types (e.g. external gear and gerotor pumps). One of the main contributions of the work is the development of an analysis procedure, which allows studying flow and pressure conditions in the TMC pump. This includes the influence of the positioning of the pump parts on spatial and temporal variations in sealing regions and the influence of pressure field propagation in relation to the valve plate position.
وصف الملف: application/pdf; text/url
العلاقة: info:eu-repo/grantAgreement/ARRS//P2-0401; https://repozitorij.uni-lj.si/IzpisGradiva.php?id=125684Test; https://repozitorij.uni-lj.si/Dokument.php?id=141525&dnTest=; https://repozitorij.uni-lj.si/Dokument.php?id=141524&dnTest=; https://plus.si.cobiss.net/opac7/bib/27653635?lang=slTest
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27دورية أكاديمية
المؤلفون: Rak, Gašper, Hočevar, Marko, Steinman, Franci
المصدر: Acta hydrotechnica, vol. 30, no. 53, pp. 107-120, 2017. ; ISSN: 0352-3551
مصطلحات موضوعية: sotočje, deroči tok, dvofazni tok, fluktuacije vodne gladine, lasersko skeniranje, confluence, supercritical flow, two-phase flow, fluctuations of water, laser scanning, info:eu-repo/classification/udc/528.8.042:627.01
الوصف: Pri deročem toku se pogosto pojavi dvofazni tok, ki ga spremlja močno razgibana, nestacionarna vodna gladina. S klasičnimi merilnimi metodami določitev povprečnega poteka vodne gladine, posebno z večjo prostorsko ločljivostjo, praktično ni možna. Pri analizi sotočja dveh deročih tokov, kjer se oblikuje stoječe valovanje z veliko vertikalno dinamiko gladine, smo za meritve gladine uporabili lasersko skeniranje. Članek prikazuje, da je z obdelavo meritev te brezkontaktne merilne metode mogoče določiti tako srednji potek kot tudi fluktuacije vodne gladine. Rezultati širijo uporabo te merilne metode, ki prinaša pomembne informacije o lastnostih vodnega toka, na številna področja hidrotehnike. Prikazane so tokovne razmere na sotočju, kjer so bile iz izmerjene dinamike vodne gladine v merilnih prerezih za nabor 168 kombinacij dveh dotokov z visokimi vrednostmi Froudovih števil (2 < Fr ; Two-phase flow often occurs in supercritical flows, accompanied by a highly dynamic, non-stationary water surface. Determining the average water surface profile, especially with higher spatial resolution, is practically impossible using conventional measurement methods. In the analysis of supercritical confluence flow, where standing waves with high vertical dynamic of water surface are formed, laser scanning was used to measure the free-water surface. Average profile as well as fluctuations of water surface can be determined with processing of (processed) measurements of this non-contact measurement method, as presented in this paper. The results contribute to wider use of this measurement method, which provides important information on water flow properties to many fields of hydro-engineering. Flow conditions are shown at confluences, where measurements of water surface dynamics in measured cross-section for 168 combinations of two flows with high values of Froude numbers (2 < Fr
وصف الملف: application/pdf; text/url
العلاقة: info:eu-repo/semantics/altIdentifier/urn/URN:NBN:SI:DOC-C35LQXZ4; https://repozitorij.uni-lj.si/IzpisGradiva.php?id=126381Test; https://repozitorij.uni-lj.si/Dokument.php?id=142315&dnTest=; https://repozitorij.uni-lj.si/Dokument.php?id=142314&dnTest=; https://plus.si.cobiss.net/opac7/bib/8268641?lang=slTest
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28دورية أكاديمية
المؤلفون: Pipp, Peter, Hočevar, Marko, Dular, Matevž
المصدر: Ultrasonics Sonochemistry, no. 77, art 105663, pp. 1-10, 2021. ; ISSN: 1350-4177
مصطلحات موضوعية: cavitation, computational fluid dynamics, numerical simulation, venturi, microchannel, kavitacija, računska dinamika fluidov, numerična simulacija, venturijeve cevi, mikrokanal, info:eu-repo/classification/udc/532.528:519.6:004.942
الوصف: The research on the potential of cavitation exploitation is currently an extremely interesting topic. To reduce the costs and time of the cavitation reactor optimization, nowadays, experimental optimization is supplemented and even replaced using computational fluid dynamics (CFD). This is a very inviting opportunity for many developers, yet we find that all too often researchers with non-engineering background treat this "new" tool too simplistic, what leads to many misinterpretations and consequent poor engineering. The present paper serves as an example of how complex the flow features, even in the very simplest geometry, can be, and how much effort needs to be put into details of numerical simulation to set a good starting point for further optimization of cavitation reactors. Finally, it provides guidelines for the researchers, who are not experts in computational fluid dynamics, to obtain reliable and repeatable results of cavitation simulations.
وصف الملف: application/pdf; text/url
العلاقة: info:eu-repo/grantAgreement/EC/H2020/771567; info:eu-repo/grantAgreement/ARRS//L4-9325; info:eu-repo/grantAgreement/ARRS//P2-0401; https://repozitorij.uni-lj.si/IzpisGradiva.php?id=128620Test; https://repozitorij.uni-lj.si/Dokument.php?id=145413&dnTest=; https://repozitorij.uni-lj.si/Dokument.php?id=145412&dnTest=; https://plus.si.cobiss.net/opac7/bib/70757891?lang=slTest
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29دورية أكاديمية
المؤلفون: Lacson, John Charles A., Zamani, Shawn A., Ribeiro Froes Jr., Luis Alberto, Mitra, Nandita, Qian, Lu, Doyle, Scarlet H., Azizi, Esther, Balestrini, Claudia, Bishop, D. Timothy, Bruno, William, Carlos Ortega, Blanca, Cuellar, Francisco, Cust, Anne E., Elder, David E., Gerdes, Anne Marie, Ghiorzo, Paola, Grazziotin, Thais Corsetti, Gruis, Nelleke A., Hansson, Johan, Hocevar, Marko, Höiom, Veronica, Holland, Elizabeth A., Ingvar, Christian, Landman, Gilles, Larre Borges, Alejandra, Mann, Graham J., Molgo, Montserrat, Facure Moredo, Luciana, Olsson, Håkan, Out Luiting, Jacoba J., Peric, Barbara, Pjanova, Dace, Puig i Sardà, Susana, Salas Alanis, Julio, Schmid, Helen, Wadt, Karin A.W., Newton-Bishop, Julia A., Kanetsky, Peter A., GenoMEL Study Group
المصدر: Articles publicats en revistes (Medicina)
مصطلحات موضوعية: Melanoma, Càncer de pell, Medicina familiar, Radiació solar, Factors de risc en les malalties, Conducta de risc (Psicologia), Skin cancer, Family medicine, Solar radiation, Risk factors in diseases, Risk-taking (Psychology)
الوصف: Background: Individuals from melanoma-prone families have similar or reduced sun-protective behaviors compared to the general population. Studies on trends in sun-related behaviors have been temporally and geographically limited. Methods: Individuals from an international consortium of melanoma-prone families (GenoMEL) were retrospectively asked about sunscreen use, sun exposure (time spent outside), sunburns, and sunbed use at several timepoints over their lifetime. Generalized linear mixed models were used to examine the association between these outcomes and birth cohort defined by decade spans, after adjusting for covariates. Results: A total of 2407 participants from 547 families across 17 centers were analyzed. Sunscreen use increased across subsequent birth cohorts, and although the likelihood of sunburns increased until the 1950s birth cohort, it decreased thereafter. Average sun exposure did not change across the birth cohorts, and the likelihood of sunbed use increased in more recent birth cohorts. We generally did not find any differences in sun-related behavior when comparing melanoma cases to non-cases. Melanoma cases had increased sunscreen use, decreased sun exposure, and decreased odds of sunburn and sunbed use after melanoma diagnosis compared to before diagnosis. Conclusions: Although sunscreen use has increased and the likelihood of sunburns has decreased in more recent birth cohorts, individuals in melanoma-prone families have not reduced their overall sun exposure and had an increased likelihood of sunbed use in more recent birth cohorts. These observations demonstrate partial improvements in melanoma prevention and suggest that additional intervention strategies may be needed to achieve optimal sun-protective behavior in melanoma-prone families.
وصف الملف: 16 p.; application/pdf
العلاقة: Reproducció del document publicat a: https://doi.org/10.1186/s12889-021-10424-5Test; BMC Public Health, 2021, vol. 21, num. 1, p. 692; https://doi.org/10.1186/s12889-021-10424-5Test; http://hdl.handle.net/2445/186116Test; 716613
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30دورية أكاديمية
المؤلفون: Jašarević, Ajdin, Hočevar, Marko, Rak, Gašper
المصدر: Defense and Security Studies; Vol. 2 (2021); 96-111 ; 2744-1741 ; 10.37868/dss.v2
الوصف: This paper describes the process of 3D analysis of two water currents with method of photogrammetry. Photogrammetry is used in fields such as architecture, engineering, police investigation, preserving cultural heritage, military and geology. This method can be used in military to reconstruct a site with traces of shrapnel or various projectiles. In our case we tried to measure height of turbulent flow, where two currents collided at the angle of 90°. In first section we introduce our problem and method. Second section describes method of photogrammetry and basics of torrential flows. In third section we describe our experiment. Fourth section describes the course of getting 3D model. In fifth section we analyze results and in sixth section, a conclusion is given.
وصف الملف: application/pdf
العلاقة: http://journals.ardascience.com/index.php/dss/article/view/175/40Test; http://journals.ardascience.com/index.php/dss/article/view/175Test
الإتاحة: https://doi.org/10.37868/dss.v2.id17510.37868/dss.v2Test
http://journals.ardascience.com/index.php/dss/article/view/175Test
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