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1.
Behaviour of coarse grain heat affected zone (HAZ) during cycle loading
Tomaž Vuherer, P. O. Maruščak, Ivan Samardžić, 2012, izvirni znanstveni članek

Opis: This paper presents results of a study on martensitic coarse grain heat affected zone that can appear in welded joints. Mechanical properties of martensitic coarse grain heat affected zone and its microstructure were investigated. Special attention was given to its behaviour during the cycle loading under stress concentration. Stress concentration was similar to the one in real welds. The S-N curve and the fatigue limit were determined. The Paris curve and the threshold for crack propagating were also determined.
Ključne besede: welded joints, coarse grain HAZ, microstructure, fatigue limit, Paris curve
Objavljeno: 01.06.2012; Ogledov: 893; Prenosov: 53
.pdf Celotno besedilo (359,02 KB)
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2.
A novel approach for assuring and following inoculum activity during kefir grains growth studies : application of dynamic pH profiles
Marko Tramšek, Andreja Goršek, 2007, izvirni znanstveni članek

Opis: The profiles of kefir grains growth curves strongly depend on bioprocess conditions and inoculum viability. Therefore, accurate growth curve studies require the use of optimally active kefir grains as inoculum. Accordingly, the main objective of our study was experimental optimization of classic kefir grains activation procedure and afterwards, comparison among growth curves of differently activated kefir grains. For this purpose some experiments were initially performed in computer-controlled RC1 reactor provided data of dynamic pH profiles during batch propagation of differently activated grains. Experimental data were mathematically analyzed and using the special methodology of minimizing the absolute deviation of pH(t) profiles the minimal time for grains activation was determined. We established that optimal inoculum activity could be ensured only by the kefir grains, which were previously activated at least over eleven successive days. In the second part of research the growth curve of optimally activated kefir grains was constructed using experimental measurements and fitted with Gompertz model. The present results were compared with the results obtained by our previous study, where classically activated grains were used. We established that, inspite of equal daily kefir grain mass increase, considerable difference in growth curves of differently activated kefir grains exist.
Ključne besede: chemical processing, kefir grains, growth curve, minimal activation time, dynamic pH profiles, Gompertz model
Objavljeno: 31.05.2012; Ogledov: 1092; Prenosov: 43
.pdf Celotno besedilo (384,93 KB)
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3.
Lie groups hierarchy in connection with the derivation of the inverse electromagnetic fine structure constant from the number of particle-like states 548, 576 and 672
Leila Marek-Crnjac, 2008, izvirni znanstveni članek

Opis: In this work we present different mathematical derivations of the inverse electromagnetic fine structure constant from the dimension of the compactified Klein modular curve, the dimension of the exceptional Lie group E8 E8 and from the number of states 548, 576 and 672. We show the close connection of the number of particle-like states 548, 576 and 672 with the dimensions of Lie groups, specially with E71/2 and other exceptional Lie groups.
Ključne besede: Lie groups, Klein-modular curve, particles
Objavljeno: 31.05.2012; Ogledov: 1455; Prenosov: 35
URL Povezava na celotno besedilo

4.
Genetic programming approach for the material flow curve determination of copper alloy - CuCrZr
Leo Gusel, Miran Brezočnik, Rebeka Rudolf, Ivan Anžel, Z. Lazarević, Nebojša Romčević, 2010, izvirni znanstveni članek

Opis: For the control of the forming process it is necessary to know as precisely as possible the flow curve of the formed material. The paper presents the determination of the equation for the flow curve of cooper alloy (CuCrZr) with artificial intelligence approach. The genetic programming method (GP) was used. It is an evolutionary optimization technique based on the Darwinist principles of the evolution of species and the survival of the fittest organisms. The main characteristic of GP is its non- deterministic way of computing. It is probably the most general approach out of evolutionary computation methods. The comparison between the experimental results, analytical solution and the solution obtained genetically clearly shows that the genetic programming method is a very promising approach.
Ključne besede: forming, flow curve, copper alloys, genetic programming
Objavljeno: 01.06.2012; Ogledov: 835; Prenosov: 10
URL Povezava na celotno besedilo

5.
An efficient approximation of arbitrary curves and surfaces using intersecting polylines and meshes
Yong Kui Liu, Jian Yun, Xiao Niu Li, Borut Žalik, 2008, izvirni znanstveni članek

Opis: This paper presents an efficient method for approximating curves and surfaces. An idea is introduced using a circle, where an arc-intersecting polyline is used instead of the traditional inner-arc polyline. The approach is then generalized to arbitrary 2D curves. The method is extended into 3D, where the approximation of spherical surface is developed based on surface-intersecting facets. Finally, a method is described for approximating the general curved surface. Theoretical analysis and the experimental results showed that the new algorithm requires considerably less geometric data at the same approximation error than the traditional one.
Ključne besede: curve, surface, approximation, engineering software
Objavljeno: 01.06.2012; Ogledov: 791; Prenosov: 50
URL Povezava na celotno besedilo

6.
The pointed version of Lipscomb's embedding theorem
Ivan Ivanšić, Uroš Milutinović, 2002

Opis: Naj bo ▫$Sigma(tau)$▫ posplošena krivulja Sierpińskega. Le-ta se lahko na naraven način identificira z Lipscombovim prostorom ▫${cal J}(tau)$▫. Tedaj za poljuben ▫$n$▫-dimenzionalni metrični prostor ▫$X$▫ s težo ▫$tau$▫ obstaja vložitev prostora ▫$X$▫ v ▫$L_n(tau) subseteq Sigma(tau)^{n+1}$▫, kjer je ▫$L_n(tau)$▫ množica vseh točk z vsaj eno iracionalno koordinato. Tu dokažemo, da to vložitev lahko izberemo tako, da v določeni točki zavzema vnaprej podano vrednost. Pravzaprav je dokazan močnejši izrek, da so vrednosti vložitve lahko vnaprej podane v točkah poljubne končne množice.
Ključne besede: matematika, topologija, dimenzija pokrivanja, posplošena krivulja Sierpińskega, univerzalni prostor, Lipscombov univerzalni prostor, vložitev, razširitev, mathematics, topology, covering dimension, generalized Sierpiński curve, universal space, Lipscomb universal space, embedding, extension
Objavljeno: 10.07.2015; Ogledov: 275; Prenosov: 23
URL Povezava na celotno besedilo

7.
Closed embeddings into Lipscomb's universal space
Ivan Ivanšić, Uroš Milutinović, 2006

Opis: Naj bo ▫${mathcal{J}}(tau)$▫ Lipscombov enodimenzionalni prostor in ▫$L_n(tau) = {x in {mathcal{J}}(tau)^{n+1}|$▫ vsaj ena koordinata od ▫{sl x}▫ je iracionalna ▫$} subseteq {mathcal{J}}(tau)^{n+1}$▫ Lipscombov ▫$n$▫-dimenzionalni univerzalni prostor s težo ▫$tau ge aleph_0$▫. V tem članku dokazujemo, da če je ▫$X$▫ poln metrizabilni prostor in velja ▫$dim X le n$▫, ▫$wX le tau$▫, tedaj obstaja zaprta vložitev prostora ▫$X$▫ v ▫$L_n(tau)$▫. Še več, vsako zvezno funkcijo ▫$f: X to {mathcal{J}}(tau)^{n+1}$▫ lahko poljubno natančno aproksimiramo z zaprto vložitvijo ▫$psi: X to L_n(tau)$▫. Razen tega sta dokazani relativna verzija in punktirana verzija. V primeru separabilnosti je dokazan analogni rezultat, v katerem je klasična trikotna krivulja Sierpińskega (ki je homeomorfna ▫${mathcal{J}}(3)$▫) nadomestila ▫${mathcal{J}(aleph_0)}$▫.
Ključne besede: matematika, topologija, dimenzija pokrivanja, posplošena krivulja Sierpińskega, univerzalni prostor, Lipscombov univerzalni prostor, vložitev, razširitev, poln metrični prostor, zaprta vložitev, mathematics, topology, covering dimension, embedding, closed embedding, generalized Sierpiński curve, universal space, Lipscomb universal space, complete metric space, extension
Objavljeno: 10.07.2015; Ogledov: 352; Prenosov: 50
URL Povezava na celotno besedilo

8.
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: 552; Prenosov: 7
URL Povezava na celotno besedilo

9.
10.
Reconstructing 3D curves with euclidean minimal spanning trees
Simon Kolmanič, Nikola Guid, 2006, izvirni znanstveni članek

Opis: In this paper, we present a new efficient algorithm for reconstruction of nonintersecting 3D curves from a sufficiently den se sample. We use the Euclidean minimal spanning trees to identify line segments reconstructing curve shapes. To deal with more than one curve in a sample and to eliminate noisy data, we introduce chains of connected line segments. With the incremental growth based on heuristics, the chains contain finally curve shapes. The method is robust and fast for both 2D and 3D curves.
Ključne besede: oblaki točk, rekonstrukcija krivulj, evklidska minimalna vpeta drevesa, point cloud, curve reconstruction, euclidean minimal spanning trees
Objavljeno: 10.07.2015; Ogledov: 647; Prenosov: 14
URL Povezava na celotno besedilo

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