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1.
Experimental Investigations of Flow and Mixing in Taylor-Couette Reactor using PIV and LIF Methods
Anna Racina, Matej Požarnik, Matthias Kind, 2005, izvirni znanstveni članek

Opis: Modern laser-optical methods (Particle Image Velocimetry and Laser Induced Fluorescence) for flow characterization are implemented to study the mixing behavior in Taylor-Couette Reactor without axial flow. In this study, cylinders with a radius-ratio equal to 0.63 are taken into account, which results in a direct transition from laminar fluid flow regime to a turbulent one. During PIV measurements special attention is paid to the system settings at which the error vector fraction is minimized. Energy dissipation rate and the distribution of local micromixing times are calculated from PN data. The average dissipation rate has values in the order of magnitude of 1▫$^{-3}$▫- 1▫$0^{-1}$▫ W/kg depending on the rotation rate of inner cylinder. The corresponding micromixing times are from 50 down to 5 ms. For LIF experiments the calibration procedure and the image processing sequence are presented. LIF data are used to study macro- and mesomixing. Macromixing in axial direction is approximated using a one-parameter model of mixing (cascade of stirred vessels). The value of diffusion coefficient (3 1▫$0^{-5}$▫) m2/s) agrees well with values published in literature. The methodology of determining the segregation index and the local mesomixing times in the flow is introduced, followed by the presentation of selected results.
Ključne besede: fluid mechanics, mixing, laser induced flourescence method
Objavljeno: 01.06.2012; Ogledov: 859; Prenosov: 33
URL Povezava na celotno besedilo

2.
Weakly coupled analysis of a blade in multiphase mixing vessel
Matej Vesenjak, Zoran Ren, Matjaž Hriberšek, 2004, kratki znanstveni prispevek

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: 01.06.2012; Ogledov: 921; Prenosov: 60
URL Povezava na celotno besedilo

3.
Estimation of solid solubilities in supercritical carbon dioxide: Peng-Robinson adjustable binary parameters in the near critical region
Mojca Škerget, Zorka Novak-Pintarič, Željko Knez, Zdravko Kravanja, 2002, izvirni znanstveni članek

Opis: The density dependence of the binary parameters of the Peng-Robinson equation of state in near the critical region was examined. Published solubility data of eight compounds in pure CO2 have been fitted to the Peng-Robinson equation in combination with one and two parameters van der Waals mixing rules and in combination with the three parameter density dependent mixing rule of Mohamed and Holder. A systematic study has been done to determine the influence of different terms in the mixing rules. In order to obtain density dependence, binary parameters were calculated for each isotherm at particular experimental point separately in the way to equalise experimental and calculated solubility data. The system was formulated as an equation-oriented model and solved by means of a nonlinear programming optimisation algorithm. For all compounds the binary interaction parameters thus obtained were found to vary strongly with pressure in the range from 75 bar to approximately 150 bar, i.e. near the critical end point (CEP) of the low temperature branch of the three phase solid-liquid-gas (SLG) curve. At higher pressures, the parameter is practically independent on pressure. In general, for the systems investigated, kij increases linearly with increasing density and reaches a constant value at higher densities in the range from 700 to 800 kg/m3, depending on the system under investigation.
Ključne besede: solid liquid equilibria, equation of state, mixing rules, binary parameters, near critical region, nonlinear programming, thermodynamic model, supercritical fluids, CO2, solubility
Objavljeno: 01.06.2012; Ogledov: 1421; Prenosov: 74
URL Povezava na celotno besedilo

4.
Influence of a random field on particle fractionation and solidification in liquid-crystal colloid mixtures
Vlad Popa-Nita, Paul van der Schoot, Samo Kralj, 2006, izvirni znanstveni članek

Opis: The influence of a random-anisotropy (RA) type disorder on the phase separation of nematogen-colloid mixtures is studied theoretically by combiningthe phenomenological Landau-de Gennes, Carnahan-Starling, and hard-sphere crystal theories. We assume that the colloids enforce the RA disorder on the surrounding thermotropic liquid-crystal (LC) molecules. We adopt the Imry-Ma argument according to which the lower-temperature phase exhibits a domain-type pattern. The colloids impose a finite degree of orientational ordering even in the isotropic (paranematic) phase. In the ordered phase they give rise to a domain-type structure, resulting in the distorted nematic (speronematic) phase. The RA field opposes the phase separation tendency. With increasing disorder the difference between the paranematic and speronematic ordering decreases. Consequently there is a critical disorder, above which both phases become identical from the orientation point of view, but have different concentrations of colloids. We have also estimated another characteristic value of disorder above which the isotropic phase can exist only in a liquid state, the crystal phase being suppressed completely.
Ključne besede: liquid crystals, transitions, segregation, mixing, random fields, solidification, complex fluids
Objavljeno: 07.06.2012; Ogledov: 758; Prenosov: 59
URL Povezava na celotno besedilo

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Automated landmark points detection by using a mixture of approaches
Božidar Potočnik, 2015, izvirni znanstveni članek

Opis: This paper deals with the automated detection of a closed curvećs dominant points. We treat a curve as a 1-D function of the arc length. The problem of detecting dominant points is translated into seeking the extrema of the corresponding 1-D function. Three approaches for automated dominant points detection are presented: (1) an approach based on fitting polynomial, (2) an approach using 1-D computer registration and (3) an innovative approach based on a multi-resolution scheme, zero-crossing and hierarchical clustering. Afterwards, two methods are introduced based on the linearly and non-linearly mixing the results from the three approaches. We then mix the results in a mean-square error sense by using the linear and non-linear fittings, respectively. We experimentally demonstrate the problem of detecting 21 landmarks on 38 vole-teeth that by mixing, the detection accuracy is improved by up to 41.47 % with respect to the results for individual approaches, as applied within the mixture.
Ključne besede: closed curve, dominant point, landmark, automated detection, mixing model fitting, vole-tooth
Objavljeno: 10.07.2015; Ogledov: 574; Prenosov: 7
URL Povezava na celotno besedilo

7.
Measurement of D0–D‾0 mixing and search for CP violation in D0 → K+K−,π+π− decays with the full Belle data set
Marko Starič, Jyoti Prakash Biswal, Marko Bračko, Boštjan Golob, Samo Korpar, Peter Križan, Tara Nanut, Rok Pestotnik, Marko Petrič, Eva Ribežl, Samo Stanič, Anže Zupanc, 2016, izvirni znanstveni članek

Opis: We report an improved measurement of $D^0–{\overline{D}}^0$ mixing and a search for $CP$ violation in $D^0$ decays to $CP$ -even final states $K^+K^−$ and $\pi^+\pi^-$. The measurement is based on the final Belle data sample of $976 fb^{−1}$. The results are $y_CP=(1.11±0.22±0.09)%$ and $A_Γ=(−0.03±0.20±0.07)%$, where the first uncertainty is statistical and the second is systematic.
Ključne besede: charm mesons, mixing, CP violation
Objavljeno: 17.07.2017; Ogledov: 343; Prenosov: 203
.pdf Celotno besedilo (577,27 KB)
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8.
First model-independent Dalitz analysis of $B^0 \to D^0K^{\ast 0}$, $D\to K_S^0\pi ^+\pi ^-$ decay
K. Negishi, Jyoti Prakash Biswal, Marko Bračko, Boštjan Golob, Samo Korpar, Peter Križan, Tara Nanut, Rok Pestotnik, Marko Petrič, Eva Ribežl, Samo Stanič, Marko Starič, Luka Šantelj, Anže Zupanc, 2016, izvirni znanstveni članek

Opis: We report a measurement of the amplitude ratio $r_S$ of $B^0 \to D^0K^{\ast 0}$ and $B^0 \to \bar {D^0}K^{\ast 0}$ decays with a Dalitz analysis of $D\to K_S^0\pi ^+\pi ^-$ decays, for the first time using a model-independent method. We set an upper limit $r_S < 0.87$ at the 68% confidence level, using the full data sample of $711\,{\rm fb}^{-1}$ corresponding to $772\times 10^6$ $B\bar {B}$ pairs collected at the $\Upsilon (4S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. This result is obtained from observables $x_- = +0.4 ^{+1.0 +0.0}_{-0.6 -0.1} \pm 0.0$, $y_- = -0.6 ^{+0.8 +0.1}_{-1.0 -0.0} \pm 0.1$, $x_+ = +0.1 ^{+0.7 +0.0}_{-0.4 -0.1} \pm 0.1$, and $y_+ = +0.3 ^{+0.5 +0.0}_{-0.8 -0.1} \pm 0.1$, where $x_\pm = r_S \cos (\delta _S \pm \phi _3)$, $y_\pm = r_S \sin (\delta _S \pm \phi _3)$, and $\phi _3\ (\delta _S)$ is the weak (strong) phase difference between $B^0 \to D^0K^{\ast 0}$ and $B^0 \to \bar {D^0}K^{\ast 0}$.
Ključne besede: CO2, CO3, Cabibbo-Kobayashi-Maskawa quark-mixing matrix, CP violation, experimental particle physics
Objavljeno: 21.07.2017; Ogledov: 370; Prenosov: 65
.pdf Celotno besedilo (555,01 KB)
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