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1.
Recent Canadian advances in nuclear-based hydrogen production and the thermochemical Cu-Cl cycle
Greg F. Naterer, S. Suppiah, M. Lewis, K. Gabriel, İbrahim Dinçer, Marc A. Rosen, Michael Fowler, G. Rizvi, E. B. Easton, B. M. Ikeda, M. H. Kaye, L. Lu, I. Pioro, P. Spekkens, P. Tremaine, J. Mostaghimi, Jurij Avsec, J. Jiang, 2009, izvirni znanstveni članek

Opis: This paper presents recent Canadian advances in nuclear-based production of hydrogen by electrolysis and the thermochemical copper-chlorine (Cu-Cl) cycle. This includes individual process and reactor developments within the Cu-Cl cycle, thermochemical properties, advanced materials, controls, safety, reliability, economic analysis of electrolysis at off-peak hours, and integrating hydrogen plants with Canada's nuclear power plants. These enabling technologies are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production from the next generation of nuclear reactors.
Ključne besede: nuclear-based hydrogen production, thermochemical copper-chlorine cycle, electrolysis
Objavljeno: 31.05.2012; Ogledov: 1283; Prenosov: 72
URL Povezava na celotno besedilo

2.
Modeling of impact toughness of cold formed material by genetic programming
Leo Gusel, Miran Brezočnik, 2006, izvirni znanstveni članek

Opis: In the paper, an approach completely different from the conventional methods for determination of accurate models for the change of properties of cold formed material, is presented. This approach is genetic programming (GP) method which is based on imitation of natural evolution of living organisms. The main characteristic of GP is its non-deterministic way of computing. No assumptions about the form and size of expressions were made in advance, but they were left to the self organization and intelligence of evolutionary process. First, copper alloy rods were cold drawn under different conditions and then impact toughness of cold drawn specimens was determined by Charpy tests. The values of independent variables (effective strain, coefficient of friction) influence the value of the dependent variable, impact toughness. On the basis of training data, different prediction models for impact toughness were developed by GP. Only the best models, gained by genetic programming were presented in the paper. Accuracy of the best models was proved with the testing data set. The comparison between deviation of genetic model results and regression model results concerning the experimental results has showed that genetic models are more precise and more varied then regression models.
Ključne besede: metal forming, genetic programming, evolutionary computing, impact toughness, copper alloy, modelling
Objavljeno: 30.05.2012; Ogledov: 1522; Prenosov: 82
URL Povezava na celotno besedilo

3.
Optical properties of plastically deformed copper
J. Trajić, Rebeka Rudolf, Ivan Anžel, M. Romčević, N. Lazarević, M. Mirić, Z. Lazarević, B. Hadžić, Nebojša Romčević, 2010, objavljeni znanstveni prispevek na konferenci

Opis: Pure copper (99.99), prepared in the sample of square cross-section (10 x 10 mm2) and length about 50 mm, was extremely plastically deformed with the repeated application of Equal Channel Angular Pressing (ECAP). ECAP was applied as an effective technique for producing bulk nano-scaled structures. Optical properties of the sample were investigated using Raman spectroscopy. Two types of lines: narrow (with width of 7 cm¡1) and wide ( 40 cm¡1) are registered. Existence of two types of lines indicates that in the specimen exists nano-sized crystal structures of both Cu and CuO related with three dimensional amorphous boundary spaces, which indicates that plastic deformation of the sample did not lead to total amorphisation of the specimen.
Ključne besede: plastically deformed copper, hydrometallurgical extraction of metals
Objavljeno: 31.05.2012; Ogledov: 1287; Prenosov: 74
URL Povezava na celotno besedilo

4.
Internal oxidation of Cu-C and Ag-C composites
Gabrijela Čevnik, Gorazd Kosec, Ladislav Kosec, Rebeka Rudolf, Borut Kosec, Ivan Anžel, 2008, kratki znanstveni prispevek

Opis: The internal oxidation in copper-carbon and silver-carbon composites occurs when they are exposed to air or oxygen at high temperature. Solubility of carbon in copper or in silver is very low. The kinetics of oxidation at high temperature and activation energy were determined and the mechanism of internal oxidation was analysed. The kinetics of internal oxidation was determined for both cases and it is depended from the diffusion of oxygen following parabolic time dependence according to Wagner's theory. The activation energy for Cu-C composite is 70.5 kJ/mol, and for Ag-C composite is 50.1 kJ/mol, what is in both cases close to the activation energy for the volume diffusion of oxygen in copper or in silver. In both cases gas products are formed during the internal oxidation of composites. In the internal oxidation zone pores, bubbles occur. The carbon oxidates directly with the oxygen from solid solution as long there is a contact, which breaks down with the presence of gas products. Then the oxidation occurs over the gas mixture of CO and CO2.Pri visokih temperaturah kompoziti bakra in srebra z ogljikom na zraku ali v kisiku reagirajo po mehanizmu notranje oksidacije. Topnost ogljika v trdnem bakru in trdnem srebru je zelo majhna. Analizirali smo kinetiko oksidacije kompozitov, določili aktivacijsko energijo in mehanizem notranje oksidacije. Kinetika oksidacije je pri obeh skupinah materialov odvisna od difuzije kisika in sledi parabolični odvisnosti od časa v skladu z Wagnerjevo teorijo. Aktivacijska energija procesa je za kompozit Cu-C enaka 70,5 kJ/mol, za kompozit Ag-C pa 50,1 kJ/mol, kar je blizu aktivacijski energiji za volumsko difuzijo kisika v trdnem bakru oziroma srebru. Pri oksidaciji kompozita nastajajo plinski produkti. Oksidacija ogljika poteka neposredno s kisikom iz trdne raztopine, ko pa se zaradi nastanka plinske faze stik prekine, pa preko plinske zmesi CO in CO2.
Ključne besede: internal oxidation, internal oxidation zone, composite, copper, silver, diffusion, kinetics
Objavljeno: 31.05.2012; Ogledov: 1323; Prenosov: 20
URL Povezava na celotno besedilo

5.
Ellipsometric measurements of plastically deformed copper
M. Mirić, Rebeka Rudolf, Ivan Anžel, B. Hadžić, M. Romčević, J. Trajić, Nebojša Romčević, 2009, objavljeni znanstveni prispevek na konferenci

Opis: Chemically pure copper (99.99) prepared in the sample of square cross-section (10 x 10 mm2) and length about 50 mm was extremely plastically deformed with the repeated application of equal channel angular pressing. Equal channel angular pressing was applied as an effective technique for producing bulk nanoscaled structures. It is well known that severe plastic deformation of metallic materials often leads to microstructure with ultrafine grains and cross-sections which remain about equal before and after deformation. Optical properties of the sample were studied using spectroscopic ellipsometry in UV-VIS range. The parameters of the sample like copper oxide and surface roughness overlayer were calculated using two-film model together with the Bruggeman effective medium approximation.
Ključne besede: hydrometallurgical extraction of metals, copper
Objavljeno: 31.05.2012; Ogledov: 1113; Prenosov: 94
URL Povezava na celotno besedilo

6.
Dependence of material characteristics on lubrication in bulk forming process
Leo Gusel, 2009, objavljeni znanstveni prispevek na konferenci

Opis: In the paper the influence of coefficient of friction (lubricant) on different properties of cold formed material has been examined. Tensile tests, hardness measurements and electrical conductivity measurements were performed.In the frame of the experimental work the process of cold forward extrusion of a cylinder made from copper alloy was investigated. The specimens were extruded at four different lubricants coefficients of friction. The results have shown that use of different lubricators with different coefficients of friction can have effects on the material properties during and after cold forming process.
Ključne besede: lubrication, cold forming, copper alloy, mechanical properties
Objavljeno: 31.05.2012; Ogledov: 1044; Prenosov: 13
URL Povezava na celotno besedilo

7.
8.
Optical properties of plastically deformed copper : an ellipsometric study
Nebojša Romčević, Rebeka Rudolf, J. Trajić, M. Romčević, B. Hadžić, Dana Vasiljević-Radović, Ivan Anžel, 2011, izvirni znanstveni članek

Opis: In this paper the results of optical properties investigations on plastically deformed copper are presented. The optical properties of the plastically deformed copper were studied using spectroscopic ellipsometry in the ultraviolet-visible (UV-VIS) range. Chemically pure copper was deformed by applying the Equal Channel Angular Pressing (ECAP) technique. During the last decade, equal-channel angular pressing procedure was used for the fabrication of ultrafine-grained metals and alloys. The plastic deformation of metallic materials leads to the production of bulk nano-scale structures with ultrafine grains and cross-sections, which remain about equal before and after deformation. The parameters of the sample were calculated using a two-film model together with the Bruggeman effective medium approximation.
Ključne besede: ellipsometric spectroscopy, atomic force microscopy, copper, amorphisation
Objavljeno: 01.06.2012; Ogledov: 1350; Prenosov: 52
.pdf Celotno besedilo (354,12 KB)
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9.
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: 964; Prenosov: 14
URL Povezava na celotno besedilo

10.
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