1. Temperature and pressure dependence of volumetric properties for binary mixtures of n-heptane and n-octaneDarja Pečar, Valter Doleček, 2007, izvirni znanstveni članek Opis: The densities of n-heptane, n-octane and their binary mixtures were measured at 298.15, 323.15 and 348.15 K and within the pressure range 0.1 to 40 MPa using a vibrating tube densimeter. The reliability of this technique has been verified in our previous works. The partial molar volumes, excess molar volumes, isothermal compressibilities, isobaric thermal expansivities and internal pressures were calculated from the obtained densities. This study presents the dependence of densities, partial molar volumes, excess molar volumes, isothermal compressibilities, isobaric thermal expansivities and internal pressures on composition, temperature and pressure.
Ključne besede: density measurements, partial molar volume, excess molar volume, isothermal compressibility, isobaric thermal expansivity, internal pressure, n-heptane, n-octane
Objavljeno v DKUM: 10.07.2015; Ogledov: 1689; Prenosov: 128
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2. Thermodynamic properties of coenzyme Q10 in supercritical carbon dioxideDarja Pečar, Valter Doleček, 2007, izvirni znanstveni članek Opis: The densities of coenzyme Q10 in supercritical carbon dioxide were measured at 308.15, 313.15, 323.15 and 333.15 K and in the pressure range from 10 to 40 MPa with the vibrating tube densimeter. The reliability of the technique has been verified in our previous works and in the present work it was checked comparing our experimental densities of pure carbon dioxide with literature data. The partial molar volumes, isothermal compressibilities, isobaric thermal expansivities, internal pressures and cluster sizes were calculated from obtained densities.
Ključne besede: koenzim Q10, density measurements, partial molar volume, isothermal compressibility, isobaric thermal expansivity, internal pressure, supercritical carbon dioxide
Objavljeno v DKUM: 01.06.2012; Ogledov: 1927; Prenosov: 147
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3. Modelling of surface crack growth under lubricated rolling-sliding contact loadingBoštjan Zafošnik, Zoran Ren, Jože Flašker, Gennady Mishuris, 2005, izvirni znanstveni članek Opis: The paper describes modelling approach to computational simulation of surface crack growth subjected to lubricated rolling-sliding contact conditions. The model considers the size and orientation of the initial crack, normal and tangential loading due to rolling-sliding contact and the influence of fluid trapped inside the crack by a hydraulic pressure mechanism. The motion of the contact sliding load is simulated with different load cases. The strain energy density (SED) and maximum tangential stress (MTS) crack propagation criteria are modified to account for the influence of internal pressure along the crack surfaces due to trapped fluid. The developed model is used to simulate surface crack growth on a gear tooth flank, which has been also experimentally tested. It is shown that the crack growth path, determined with modified crack propagation criteria, is more accurately predicted than by using the criteria in its classical form.
Ključne besede: fracture mechanics, numerical methods, contact loading, finite element analysis, internal pressure, maximum tangential stress, strain energy density, surface crack growth
Objavljeno v DKUM: 01.06.2012; Ogledov: 2689; Prenosov: 97
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4. Volumetric properties of ethanol-water mixtures under high temperatures and pressuresDarja Pečar, Valter Doleček, 2005, izvirni znanstveni članek Opis: The densities of ethanol and ethanol-water mixtures were measured with a vibrating tube densimeter at 25.0, 50.0 and 75.0°C in the pressure range from 0.10 to 40.00 MPa. Densities were correlated using an empirical model. Partial molar volumes, excess molar volumes, isothermal compressibilities, cubic expansion coefficients and internal pressures were calculated from obtained densities. This study reports the dependence of densities, partial molar volumes, excess molar volumes, isothermal compressibilities, cubic expansion coefficients and internal pressures on composition, temperature and pressure.
Ključne besede: ethanol, ethanol-water mixtures, density measurements, vibrating U tube densimeter, partial molar volumes, isothermal compressibility, isobaric expansibility, cubic expansion coefficient, internal pressure
Objavljeno v DKUM: 01.06.2012; Ogledov: 2656; Prenosov: 146
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