Sample records for 10.3846

  1. Numerical Solution of the Time-Dependent Navier–Stokes Equation for Variable Density–Variable Viscosity. Part I

    Axelsson, Owe; Xin, H.; Neytcheva, M.


    Roč. 20, č. 2 (2015), s. 232-260 ISSN 1392-6292 Institutional support: RVO:68145535 Keywords : variable density * phase-field model * Navier-Stokes equations * preconditioning * variable viscosity Subject RIV: BA - General Mathematics Impact factor: 0.468, year: 2015

  2. Comparison of the actual costs during removal of concrete layer by high-speed water jets

    Hela, R.; Bodnárová, L.; Novotný, M.; Sitek, Libor; Klich, Jiří; Wolf, I.; Foldyna, Josef


    Roč. 13, č. 4 (2012), s. 763-775 ISSN 1611-1699 R&D Projects: GA MŠk ED2.1.00/03.0082 Grant - others:GA TA ČR(CZ) TA01010948; GA MPO(CZ) FR-TI1/387 Institutional support: RVO:68145535 Keywords : computation model * total technological costs * total fixed costs * total variable costs * Triple helix model Subject RIV: JQ - Machines ; Tools Impact factor: 1.881, year: 2012

  3. Highway Design on the Sections Affected by Aquaplaning

    Aleksandr Reznik


    Full Text Available Pouring rain, snow melting, water condensing, fog and other natural phenomena cause the collection of water on roadway pavement, leading to the decrease of road-holding capacity of a tyre.When a car or a light truck is moving at a high speed on wet road pavement, the water under its wheels cannot be expelled in time.It results in raising of the front wheels of the vehicle above the road surface under the action of a hydrodynamic force and loss of vehicle control.The methods ensuring traffic safety on road sections, where vehicle’s aquaplaning is possible, should be developed by identifying and improving these sections at the stages of highway design, reconstruction and maintenance and by limiting traffic speed of vehicles.Keywords: vehicle, road, road-holding capacity, aquaplaning, reconstruction, maintenance, traffic safety.DOI: 10.3846/mla.2009.6.06

  4. Studies and Analysis of the Effectiveness of Stormwater Runoff Purification Equipment in Vilnius

    Egidija Jaruševičiūtė


    Full Text Available In order to protect the natural environment from pollution, pollutant reduction in the stormwater runoff of urban areas is a particularly relevant factor. Uneven surface water flow and changes in pollutant concentration complicate conventional matching techniques and processes as well as prolong the duration of time which requires a comprehensive study in this area. Therefore, experiments on inflow stormwater turbidity and impurity with suspended solids and petroleum products were carried out according to the prepared sample collecting methodology. The study evaluated the effectiveness of cleaning a stormwater treatment plant along the settlement chamber in the chosen points. The settling time of impurities found in stormwater was analyzed under the presence of ideal conditions in the laboratory. The conducted experiments established dependence between suspended solids and turbidity. Stormwater pollution by SS was reduced only to 21–35% after heavy rain or a snow melting period in treatment plants. Keywords: storm water runoff, cleaning stormwater treatment plant, pollutants, turbidity, suspended solids, petrol products.DOI: 10.3846/mla.2010.087

  5. Analysis of the Numerical Modelling of Turbulence in the Conical Reverse-Flow Cyclone

    Inga Jakštonienė


    Full Text Available The paper describes the numerical modelling of the swirling fluid flow in the Stairmand cyclone (conical reverse-flow – CRF with tangential inlet (equipment for separating solid particles from the gaseous fluid flow. A review of experimental and theoretical papers is conducted introducing three-dimen­sional differential equations for transfer processes. The numerical modelling of the Stairmand cyclone the height of which is 0.75 m, diameter – 0.17 m, the height of a cylindrical part – 0.290 m, a conical part – 0,39 m and an inlet area is 0,085×0,032 m is presented. When governing three-dimensional fluid flow, transfer equations Navje-Stokes and Reynolds are solved using the finite volume method in a body-fitted co-ordinate system using standard k– e and RNG k– e model of turbulence. Modelling is realised for inlet velocity 4.64, 9.0 and 14.8 m/s (flow rate was 0.0112, 0.0245 and 0.0388 m3/s. The results obtained from the numerical tests have demonstrated that the RNG k– e model of turbulence yields a reasonably good prediction for highly swirling flows in cyclones: the presented numerical results (tangential and radial velocity profiles are compared with numerical and experimental data obtained by other authors. The mean relative error of ± 7,5% is found. Keywords: cyclone, solid particles, numerical modelling, turbulence, one-phase flow.DOI: 10.3846/mla.2010.085

  6. Microbial activity and soil organic matter decay in roadside soils polluted with petroleum hydrocarbons

    Mykhailova, Larysa; Fischer, Thomas; Iurchenko, Valentina


    positively correlated with the carbohydrate fraction and negatively correlated with the aliphatic fraction of the soil C, while carbohydrate-C and alkyl-C increased and decreased with distance from the road, respectively. It is proposed that petroleum hydrocarbons supress soil biological activity at concentrations above 1500 mg kg-1, and that soil organic matter priming primarily affects the carbohydrate fraction of soil organic matter. It can be concluded that the abundance of solid carbohydrates (O-alkyl C) is of paramount importance for the hydrocarbon mineralization under natural conditions, compared to more recalcitrant SOM fractions (mainly aromatic and alkyl C). References Mykhailova, L., Fischer, T., Iurchenko, V. (2013) Distribution and fractional composition of petroleum hydrocarbons in roadside soils. Applied and Environmental Soil Science, vol. 2013, Article ID 938703, 6 pages, DOI 10.1155/2013/938703 Mykhailova, L., Fischer, T., Iurchenko, V. (2014) Deposition of petroleum hydrocarbons with sediment trapped in snow in roadside areas. Journal of Environmental Engineering and Landscape Management 22(3):237-244, DOI 10.3846/16486897.2014.889698 Nelson P.N. and Baldock J.A. (2005) Estimating the molecular composition of a diverse range of natural organic materials from solid-state 13C NMR and elemental analyses, 2005, Biogeochemistry (2005) 72: 1-34, DOI 10.1007/s10533-004-0076-3 Zyakun, A., Nii-Annang, S., Franke, G., Fischer, T., Buegger, F., Dilly, O. (2011) Microbial Actvity and 13C/12C Ratio as Evidence of N-Hexadecane and N-Hexadecanoic Acid Biodegradation in Agricultural and Forest Soils. Geomicrobiology Journal 28:632-647, DOI 10.1080/01490451.2010.489922