1. New Approach for Fertiliser Size Assessment Using Contactless ScanningAndrius Laucka, Darius Andriukaitis, Algimantas Valinevicius, Mindaugas Zilys, Dangirutis Navikas, Leonas Balasevicius, Audrius Merfeldas, Roman Sotner, Jan Jerabek, Zhixiong Li, Jožef Ritonja, 2023, izvirni znanstveni članek Ključne besede: camera, particle, measurement, silhuette, volume, position Objavljeno v DKUM: 22.05.2024; Ogledov: 157; Prenosov: 8 Celotno besedilo (3,99 MB) Gradivo ima več datotek! Več... |
2. Coupling of nematic in-plane orientational ordering and equilibrium shapes of closed flexible nematic shellsLuka Mesarec, Wojciech Góźdź, Veronika Kralj-Iglič, Samo Kralj, Aleš Iglič, 2023, izvirni znanstveni članek Opis: The impact of the intrinsic curvature of in-plane orientationally ordered curved flexible nematic molecules attached to closed 3D flexible shells was studied numerically. A Helfrich-Landau-de Gennes-type mesoscopic approach was adopted where the flexible shell’s curvature field and in-plane nematic field are coupled and concomitantly determined in the process of free energy minimisation. We demonstrate that this coupling has the potential to generate a rich diversity of qualitatively new shapes of closed 3D nematic shells and the corresponding specific in-plane orientational ordering textures, which strongly depend on the shell’s volume-to-surface area ratio, so far not predicted in mesoscopic-type numerical studies of 3D shapes of closed flexible nematic shells. Ključne besede: orientational ordering, curved nematic molecules, flexible nematic shells, equilibrium shapes, relative volume Objavljeno v DKUM: 25.03.2024; Ogledov: 280; Prenosov: 11 Celotno besedilo (2,66 MB) Gradivo ima več datotek! Več... |
3. Post-liquefaction volume change in micaceous sandy of Old Gediz River DeltaEnder Basari, Gurkan Ozden, 2013, izvirni znanstveni članek Opis: Post-liquefaction settlement characteristics of micaceous sands are not well investigated topic. Currently available charts relating post-liquefaction volumetric strain to relative density were developed for clean sand. Estimation of post-liquefaction settlement of micaceous sands, therefore, may stay on the unsafe side, since there is evidence indicating that mica grains could increase volume change tendency. Influence of mica content on post-liquefaction volumetric strain of sand-mica mixtures is studied in this article. Soil samples were prepared at various relative densities. Influence of fine content that could be present in the field was also investigated on tamped natural field samples recovered from boreholes drilled in a highly populated alluvial site known as the Old Gediz River Delta of Izmir. It was found that increasing mica content at a certain relative density resulted in higher volumetric strains as compared with the data on clean sands. It is deduced that influence of mica grains on sand behavior depends on initial void ratio of sand. Effects of mica grains decrease with increasing of relative density. Simple empirical relationships were derived relating mica content and relative density to volumetric strain. It was also noticed that fine content accelerated and increased post-liquefaction volumetric strains. Ključne besede: sand, mica, non-plastic fines, post-liquefaction volume change Objavljeno v DKUM: 14.06.2018; Ogledov: 900; Prenosov: 95 Celotno besedilo (434,60 KB) Gradivo ima več datotek! Več... |
4. Innovative solution principles of wave problems in horizontaly layered mediasAndrej Štrukelj, Andrej Umek, Tomaž Pliberšek, 2006, izvirni znanstveni članek Opis: The paper presents engineeringly reasonable transformation of surface displacements of horizontally layered half-space. The latter shows in the half-space present types of waves. It is shown that surface waves are expressed through residuums in poles of the integrand and the volume waves are expressed as integrals along corresponding branch cuts. The singularity which always appears in the basic singular solution in elastodynamics is in this case exactly excluded. In the second part of the paper the behaviour of Stonely waves is investigated in greater detail. It is shown that in the case of layers of finite thickness their appearance and velocities depends not onlyon the material characteristics of neighbouring layers but also on their thickness. Ključne besede: geomechanics, horizontally layered halfspace, volume waves, surface waves, Green`s function, Stonely waves Objavljeno v DKUM: 17.05.2018; Ogledov: 1523; Prenosov: 154 Celotno besedilo (613,03 KB) Gradivo ima več datotek! Več... |
5. Impact of curvature on nematic topological defectsLuka Mesarec, 2018, doktorska disertacija Opis: Topological defects (TDs) appear almost unavoidably in continuous symmetry breaking phase transitions. The topological origin makes their key features independent of systems' microscopic details; therefore TDs display many universalities. Because of their strong impact on numerous material properties and their significant role in several technological applications it is of strong interest to find simple and robust mechanisms controlling the positioning and local number of TDs. There are strong evidences that in physics the fields are fundamental entities of nature and not particles. If this is the case then topological defects (TDs) might play the role of fundamental particles. An adequate testing ground to study and gain fundamental understanding of TDs are nematic liquid crystals. We present a numerical study of TDs within effectively two dimensional closed soft films exhibiting in-plane orientational ordering. Popular examples of such class of systems are liquid crystalline shells and various biological membranes.
We analyze the impact of extrinsic and intrinsic curvature on positions of topological defects (TDs) in two-dimensional (2D) nematic films. We demonstrate that both these curvature contributions are commonly present and are expected to be weighted by comparable elastic constants. A simple Landau-de Gennes approach in terms of tensor nematic order parameter is used to numerically demonstrate impact of the curvatures on position of TDs on 2D ellipsoidal nematic shells. We introduce the Effective Topological Charge Cancellation mechanism controlling localised positional assembling tendency of TDs and the formation of pairs (defect,antidefect) on curved surfaces. Furthermore, we estimate a critical depinning threshold to form pairs (defect,antidefect) using the electrostatic analogy. Finally, we show how one could efficiently switch among qualitatively different structures by using a relative volume of ordered shells, which represents a relatively simple naturally accessible control parameter.
In doctoral thesis, we developed theoretical model of erythrocyte membrane by using a hybrid Helfrich-Landau type mesoscopic approach, taking into account in-plane membrane ordering. We demonstrate that the derived extrinsic membrane energy term, which strongly depends on the local orientations of the molecules, is essential for the predicted broadening of the range of the relative volumes corresponding to the stable discocyte shapes, which is otherwise very narrow if only intrinsic curvature energy term dominates. Ključne besede: Topological defects, Continuum fields, Nematic liquid crystals, Biological membranes, Nematic shells, Landau-de Gennes formalism, Topological charge, Nanoparticles, Gaussian curvature, Electrostatic analogy, Intrinsic curvature, Extrinsic curvature, Crystal growth nucleation, Relative
volume Objavljeno v DKUM: 09.03.2018; Ogledov: 2391; Prenosov: 241 Celotno besedilo (23,66 MB) |
6. Računalniško simuliranje postopka kovanjaJanez Stupan, Iztok Potrč, 2000, strokovni članek Opis: V prispevku je obravnavano tridimenzionalno računalniško simuliranje procesa kovanja z računalniškim programom MSC/SuperForge. Kovanje je izrazit proces tridimenzionalne deformacije, med katerim se stalno spreminjajo robni pogoji. Začetna oblika je v večini primerov preprosta, končna oblika pa je lahko zelo zahtevna in se doseže s preoblikovanjem v več stopnjah. Rezultati simuliranja so: deformirana oblika, temperaturno polje, polje toka materiala, tlaka, dejanske napetosti, dejanskih plastičnih deformacij itn. Ključne besede: forging, deformation, finite volume method, material flow Objavljeno v DKUM: 10.07.2015; Ogledov: 1463; Prenosov: 69 Povezava na celotno besedilo |
7. 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: 123 Celotno besedilo (191,46 KB) Gradivo ima več datotek! Več... |
8. On new approach to rheological modeling of an electrostatic ash and water - quadratic lawPrimož Ternik, 2002, objavljeni znanstveni prispevek na konferenci Opis: In the paper a new rheological model for an electrostatic ash and water mixture is proposed. The fundamental equation of the rheological model was used to determine the relationship between the shear stress and the shear rate as well as the equation of a velocity profile for the flow through a straight pipe. Experimental results obtained from a capillary viscometer were used as the basis to determine the parameters for the proposed model by the non-linear regression analysis. With the Quadratic law a numerical analysis of a mixture flow through a capillary pipe with the finite volume method was performed. The derived equations for the velocity profile, shear stress and shear rate were validated through a comparison of numerically obtained and theoretical results. Finally, the compariosn between the Quadratic and the Power law is presented. Ključne besede: fluid mechanics, non-Newtonian fluids, mixture of electrofilter ash and water, flow in pipes, capillary pipes, rheological model, velocity profile, shear stress, finite volume method, numerical analysis, quadratic law, power law, mehanika fluidov Objavljeno v DKUM: 01.06.2012; Ogledov: 2434; Prenosov: 46 Povezava na celotno besedilo |
9. Pristop k vizualizaciji podatkov na osebnem računalnikuDavid Podgorelec, Marko Vinter, Borut Žalik, 2002, izvirni znanstveni članek Opis: V članku je predstavljen algoritem za senčenje prostorskih podatkov, ki je zaradi svoje enostavnosti in hitrosti primeren tudi za uporabo na osebnem računalniku. Množice podatkov, ki jih je zmožen vizualizirati, so dovolj velike za učinkovito rabo v medicinskih aplikacijah. Algoritem temelji na sekundarnem geometrijskem modelu, ki smo ga poimenovali seznam vidnih vokslov. Vizualizacijo poskuša pospešiti s predhodnim izločanjem vokslov, nezanimivih za uporabnika. Ti tako imenovani beli voksli predstavljajo zrak, notranjost objektov in dele površja objektov, ki niso vidni iz trenutnega položaja opazovalca. Delovanje in učinkovitost algoritma smo predstavili na nekaj praktičnih primerih uporabe pri vizualizaciji medicinskih podatkov. Ključne besede: računalniška grafika, prostorski podatki, senčenje prostorskih podatkov, znanstvena vizualizacija, vizualizacija prostorskih podatkov, izdelava modelov, voksli, vizualizacija medicinskih podatkov, computer graphics, volume data, volume rendering, visualisation, volume data visualisation, voxels, medical data sets Objavljeno v DKUM: 01.06.2012; Ogledov: 2123; Prenosov: 53 Povezava na celotno besedilo |
10. Weakly coupled analysis of a blade in multiphase mixing vesselMatej Vesenjak, Zoran Ren, Matjaž Hriberšek, 2004, drugi znanstveni članki Opis: Two or more physical systems frequently interact with each other, where the independent solution of one system is impossible without a simultaneous solution of the others. An obvious coupled system is that of a dynamic fluid-structure interaction. š8đ In this paper a computational analysis of thefluid-structure interaction in a mixing vessel is presented. In mixing vessels the fluid can have a significant influence on the deformation of blades during mixing, depending on speed of mixing blades and fluid viscosity.For this purpose a computational weakly coupled analysis has been performed to determine the multiphase fluid influences on the mixing vessel structure. The multiphase fluid field in the mixing vessel was first analyzed with the computational fluid dynamics (CFD) code CFX. The results in the form of pressure were then applied to the blade model, which was the analysed with the structural code MSC.visualNastran forWindows, which is based on the finiteelement method (FEM). Ključne besede: fluid mechanics, solid mechanics, coupled problems, computational analysis, two-phase fluid, mixing blade, pressure distribution, finite volume method, finite element method Objavljeno v DKUM: 01.06.2012; Ogledov: 1877; Prenosov: 93 Povezava na celotno besedilo |