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A method to compute the number of regular reversible Rosenberg hypergroup
Ali Tavakoli, Morteza Jafarpour, Irina Cristea, 2016, izvirni znanstveni članek

Opis: The purpose of this note is the study of the hypergroups associated with binary relations. New types of matrices, called i-very good and regular reversible matrices, are introduced in order to give some properties of the Rosenberg hypergroups related to them. A program written in $MATLAB$ computes the number of these hypergroups up to isomorphism.
Najdeno v: ključnih besedah
Ključne besede: hypergroup, binary relation, regular reversible hypergroup, Boolean matrix
Objavljeno: 02.09.2016; Ogledov: 2774; Prenosov: 0
.pdf Polno besedilo (309,47 KB)

Tungsten carbide thin films for electrochemical water splitting studies
Hasan Okuyucu, Matjaz Valant, Ali Semerci, Cesur Altinkaya, Saim Emin, Abdullah Yildiz, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: We used wet-chemistry techniques to prepare colloidal tungsten (W) nanoparticles (NPs). The synthesis of W NPs was conducted using the so called hot-matrix method in 1-octadecene [1]. The sizes of obtained W NPs are in the order of 2 - 5 nm. These W NPs are coated with hydrophobic molecules which allow their dispersion in organic solvents like choloroform (CHCl3). It was found that the colloidal stability of the dispersions is exceptionally high exceeding several years. The stability of W NPs which prevents coagulation allows the preparation of thin films with uniform thicknesses by spin-coating, inkjet-printing and spray coating. We have prepared tungsten carbide (W2C, WC) thin films. The preparation of W2C and WC was achieved by spin-coating of pre-synthesized W NPs on graphite substrate and following heat treatment under Ar atmosphere at 1000 and 1450°C. The obtained W2C and WC films were used both in electrochemical water splitting studies. We also made a composite W2C-Pt films where we used only 5 at.% of Pt. The W2C-Pt composite has shown similar performance as pure Pt-C for hydrogen (H2) evolution. In conclusion, we have developed a procedure for the synthesis of W NPs which can be applied for the preparation of tungsten carbides films and their use for electrochemical water splitting.
Najdeno v: ključnih besedah
Povzetek najdenega: ...NPs was conducted using the so called hot-matrix method in 1-octadecene [1]. The sizes of...
Ključne besede: water splitting, nanoparticles, hot-matrix
Objavljeno: 09.10.2017; Ogledov: 3780; Prenosov: 0
.pdf Polno besedilo (376,30 KB)

Boundary element simulation of linear water waves in a model basin
Clemens Hofreither, Ulrich Langer, Satyendra Tomar, 2010, objavljeni znanstveni prispevek na konferenci

Najdeno v: ključnih besedah
Ključne besede: boundary element method, linear water waves, hierarchical matrix representation, data-sparse matrix approximation
Objavljeno: 13.11.2018; Ogledov: 1612; Prenosov: 19
.pdf Polno besedilo (210,55 KB)
Gradivo ima več datotek! Več...

Evaluation of recently-proposed secondary organic aerosol models for a case study in Mexico City
Katja Džepina, R. M. Volkamer, Sasha Madronich, P. Tulet, I. M. Ulbrich, Q. Zhang, C. D. Cappa, P. J. Ziemann, Jose L. Jimenez, 2009, izvirni znanstveni članek

Opis: Recent field studies have found large discrepancies in the measured vs. modeled SOA mass loadings in both urban and regional polluted atmospheres. The reasons for these large differences are unclear. Here we revisit a case study of SOA formation in Mexico City described by Volkamer et al. (2006), during a photochemically active period when the impact of regional biomass burning is minor or negligible, and show that the observed increase in OA/Delta CO is consistent with results from several groups during MILAGRO 2006. Then we use the case study to evaluate three new SOA models: 1) the update of aromatic SOA yields from recent chamber experiments (Ng et al., 2007); 2) the formation of SOA from glyoxal (Volkamer et al., 2007a); and 3) the formation of SOA from primary semivolatile and intermediate volatility species (P-S/IVOC) (Robinson et al., 2007). We also evaluate the effect of reduced partitioning of SOA into POA (Song et al., 2007). Traditional SOA precursors (mainly aromatics) by themselves still fail to produce enough SOA to match the observations by a factor of similar to similar to 7. The new low-NOx aromatic pathways with very high SOA yields make a very small contribution in this high-NOx urban environment as the RO2 center dot+NO reaction dominates the fate of the RO2 center dot radicals. Glyoxal contributes several mu g m(-3) to SOA formation, with similar timing as the measurements. P-S/IVOC are estimated from equilibrium with emitted POA, and introduce a large amount of gas-phase oxidizable carbon that was not in models before. With the formulation in Robinson et al. (2007) these species have a high SOA yield, and this mechanism can close the gap in SOA mass between measurements and models in our case study. However the volatility of SOA produced in the model is too high and the O/C ratio is somewhat lower than observations. Glyoxal SOA helps to bring the O/C ratio of predicted and observed SOA into better agreement. The sensitivities of the model to some key uncertain parameters are evaluated.
Najdeno v: ključnih besedah
Ključne besede: polycyclic aromatic-hydrocarbons, positive matrix factorization, mass-spectrometry, volatility measurements
Objavljeno: 11.04.2021; Ogledov: 355; Prenosov: 0
.pdf Polno besedilo (1,18 MB)

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