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211 - 220 / 4631
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211.
Kanarski otoki v plamenih
Uroš Slak, Samo Stanič, Natalija Švab, radio or television event

Abstract: Intervju o izbruhu ognjenika Cumbre Vieja na La Palmi, Kanarski otoki, Španjia, ter o raziskavah v okviru projekta Polje Čerenkovih teleskopov (CTA), ki potekajo na observatoriju Roque de los Muchachos.
Keywords: ognjenik, izbruh, astrofizika, gama žarki visokih energij, atmosfera, lidar
Published: 04.10.2021; Views: 277; Downloads: 0
.pdf Fulltext (189,76 KB)

212.
Komunikacija eholokacija
Andreea Oarga-Mulec, 2021, artistic performance

Published: 04.10.2021; Views: 243; Downloads: 1
.pdf Fulltext (1,97 MB)
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213.
Pregled, analiza in predlog alternativne oskrbe z energijo - LDC Letališka
Henrik Gjerkeš, 2021, treatise, preliminary study, study

Abstract: Osnovna varianta temelji na podatkih, dimenzijah in ocenah v že izdelani projektni dokumentaciji, razen v tistih delih, kjer smo lahko podali natančnejše ocene na osnovi namensko pridobljenih podatkov in ocen v času izdelave te analize od dobavitelja toplotne energije Energetika Ljubljana, Statističnega urada RS in renomiranega slovenskega proizvajalca in projektanta sistemov na osnovi vrhunskih toplotnih črpalk Kronoterm. V predlagani varianti 1 se ogrevanje prostorov izvede s toplotnimi črpalkami voda/voda in priklop na sistem daljinskega ogrevanja v določenem obsegu. Hlajenje prostorov je izvedeno z istimi toplotnimi črpalkami voda/voda, ta varianta pa omogoča tudi pasivno hlajenje s podtalnico. Varianta 1 poleg okoljskih (gretje in hlajenje prostorov LDC Mercator z 68,5 % obnovljivih virov energije) kaže tudi izrazite ekonomske prednosti pred osnovno varianto: • za 280.000 EUR ali za 47 % nižja investicija; • za 76.504 EUR ali za 54 % nižji letni vseživljenjski stroški; • v 15 letih 1.469.270 EUR prihranka pri oskrbi z energijo. Posebej opozarjamo na dvigovanje cene EU-ETS emisijskih kuponov, ki bodo glede na napovedi tudi v bodoče imeli pomembnejši vpliv na ceno toplote iz sistema daljinskega ogrevanja Energetika Ljubljana. Investicija v sončno elektrarno izboljša finančni tok oskrbe z energijo LDC Mercator v vseh variantah in kljub visoki investiciji v 15 letih investitorju prinese občutne finančne koristi ter dvigne delež obnovljivih virov na 76,9 %. Prodaja odpadne toplote izboljša finančno bilanco oskrbe z energijo LDC Mercator, vendar zahteva dodatno investicijo in je občutljiva na odkupno ceno odpadne toplote. Rast cene emisijskih kuponov kljub vsemu daje nezanemarljivi potencial tej varianti in je po preliminarnih informacijah zanimiva za Energetiko Ljubljana, še posebej v kombinaciji z aktualnim razpisom Norveškega mehanizma, ki izkoriščanja podtalnice uvršča med upravičene namene. Analiza občutljivosti pokaže, da ima zvišanje cene toplote iz SDO ali električne energije manjši vpliv na predlagano varianto 1 v vseh kombinacijah, kot na osnovno varianto. Pri variantah s sončno elektrarno je NSV bolj občutljiva na višino investicije, vendar podražitev električne energije pri vseh variantah prinese zmanjšanje vseživljenjskih stroškov. Zvišanje cene toplote iz SDO ima zanemarljiv vpliv na vseživljenjske stroške predlagane variante 1, kar zmanjšuje tveganje zvišanja stroškov za ogrevanje zaradi nepredvidljive, a hitro naraščajoče cene emisijskih kuponov, ki jih z administrativnimi ukrepi ne moremo kompenzirati. Visok delež obnovljivih virov energije pri predlagani varianti 1 v vseh oblikah omogoča, da na ne-administrativen način LDC Mercator izpolni standarde skoraj nič-energijskih stavb (sNES) in s tem stopi med vodilne primere dobre prakse trajnostne gradnje.
Keywords: oskrba z energijo, trajnostna energija, Mercator
Published: 04.10.2021; Views: 257; Downloads: 0
.pdf Fulltext (306,82 KB)

214.
Znanstvena konferenca Kozmični anarhizem, 6.-8.april 2021, online
2021, other performed works

Published: 04.10.2021; Views: 232; Downloads: 0
.pdf Fulltext (391,53 KB)

215.
Apstraktni dinamički ambijent Avgusta Černigoja i tršćanske konstruktivističke grupe
Kristina Pranjić, 2021, independent scientific component part or a chapter in a monograph

Abstract: The article presents the Trieste Constructivist Cabinet (1927) by Slovenian avant-gardist Avgust Černigoj and his Constructivist group, as one of the significant events in the context of abstract artistic ambient of historical avant-garde. El Lissitzky’s Proun is pointed out as the greatest influence on this artwork, while at the same time presenting the thesis of its original contribution, in the sense of dynamization of the cabinet using Stepančič’s levitation constructions. The kinetic potential of these hanging constructions draws the visitor into a two-way communication, a permanent feedback loop. It is this continuum, the duration i.e. process nature that such an installation allowed, i.e. produces, that is placed in the forefront, alongside space and motion. In addition to this pinnacle of Slovenian avant-garde being placed in the context of European historical avant-garde, the work of the Slovenian constructivists is also contextualized within the framework of the Yugoslav avant-garde movements. Special attention is paid to the Tank magazine (1927), which started being published in Ljubljana after the ban on the publication of Zenit in 1926, in an attempt to maintain continuity in the publication of Yugoslav avant-garde periodicals. It is a known fact that Černigoj’s avant-garde art was based on constructivist principles, while the article also points out his concurrent use of subversive Dadaist principles: the process of destruction of old meanings using methods of isolation and relocation of artistic material, in the sense of ready made or objet trouvé; similarly, desemantization is carried out in the linguistic material (“g”, “jublj”); use of mass produced materials (fragments of slogans that the artist transposes into artistic rhetoric); the performative nature of the entire event / exhibition. Also presented are the close ties between Slovenian constructivism and Micić’s Zenitism and Dragan Aleksić’s Dadaism, as well as the shift in the sense of forming an original program and establishing an own avant-garde formation, whose most important and most representative work is precisely the Trieste Constructivist Cabinet, which represents a characteristic synthesis of the Yugoslav and the European avant-garde tendencies at the time.
Keywords: Avgust Černigoj, slovenski konstruktivizem, Tržaški konstruktivistični ambient, revija Tank, El Lissitzky, Edvard Stepančič, instalacija v umetnosti, abstraktni ambient, zenitizem, dadaizem
Published: 04.10.2021; Views: 245; Downloads: 0
.pdf Fulltext (941,08 KB)

216.
Experimental bounds on sterile-active neutrino mixing angles
Mihael Petač, 2015, master's thesis

Abstract: Despite the success of the Standard Model in the last few decades, we know it is not complete. There is strong motivation for assuming the existence of additional heavy neutral leptons, which can account for active neutrino masses and possibly also have cosmological implications. In this work I consider the Standard Model with two neutral lepton singlets (sterile neutrinos) with degenerated masses in the range 20MeV - 2GeV. The constraints on the active-sterile neutrino mixing angles are evaluated based on recent neutrino oscillations data. Using these constraints the bounds from accelerator experiments are reanalyzed for the case of the considered model. Finally, the results are compared with cosmological constraints coming from Big Bang nucleosynthesis and the nMSM resonant leptogenesis.
Keywords: Sterile neutrinos, Neutrino mixing, See-saw, High-Energy Physics - Phenomenology, High-Energy Physics - Experiments
Published: 01.10.2021; Views: 274; Downloads: 8
.pdf Fulltext (1,93 MB)

217.
Determination of the multiple-scattering correction factor and its cross-sensitivity to scattering and wavelength dependence for different AE33 Aethalometer filter tapes
Andres Alastuey, Griša Močnik, Vera Bernardoni, Jesús Yus-Díez, Davide Ciniglia, Matic Ivančič, Xavier Querol, Noemí Perez, Cristina Reche, Martin Rigler, Roberta Vecchi, Sara Valentini, Marco Pandolfi, 2021, original scientific article

Abstract: Providing reliable observations of aerosol particles' absorption properties at spatial and temporal resolutions suited to climate models is of utter importance to better understand the effects that atmospheric particles have on climate. Nowadays, one of the instruments most widely used in international monitoring networks for in situ surface measurements of light absorption properties of atmospheric aerosol particles is the multi-wavelength dual-spot Aethalometer, AE33. The AE33 derives the absorption coefficients of aerosol particles at seven different wavelengths from the measurements of the optical attenuation of light through a filter where particles are continuously collected. An accurate determination of the absorption coefficients from the AE33 instrument relies on the quantification of the non-linear processes related to the sample collection on the filter. The multiple-scattering correction factor (C), which depends on the filter tape used and on the optical properties of the collected particles, is the parameter with both the greatest uncertainty and the greatest impact on the absorption coefficients derived from the AE33 measurements. Here we present an in-depth analysis of the AE33 multiple-scattering correction factor C and its wavelength dependence for two different and widely used filter tapes, namely the old, and most referenced, TFE-coated glass, or M8020, filter tape and the currently, and most widely used, M8060 filter tape. For performing this analysis, we compared the attenuation measurements from AE33 with the absorption coefficients measured with different filter-based techniques. On-line co-located multi-angle absorption photometer (MAAP) measurements and off-line PP_UniMI polar photometer measurements were employed as reference absorption measurements for this work. To this aim, we used data from three different measurement stations located in the north-east of Spain, namely an urban background station (Barcelona, BCN), a regional background station (Montseny, MSY) and a mountaintop station (Montsec d'Ares, MSA). The median C values (at 637 nm) measured at the three stations ranged between 2.29 (at BCN and MSY, lowest 5th percentile of 1.97 and highest 95th percentile of 2.68) and 2.51 (at MSA, lowest 5th percentile of 2.06 and highest 95th percentile of 3.06). The analysis of the cross-sensitivity to scattering, for the two filter tapes considered here, revealed a large increase in the C factor when the single-scattering albedo (SSA) of the collected particles was above a given threshold, up to a 3-fold increase above the average C values. The SSA threshold appeared to be site dependent and ranged between 0.90 to 0.95 for the stations considered in the study. The results of the cross-sensitivity to scattering displayed a fitted constant multiple-scattering parameter, Cf, of 2.21 and 1.96, and a cross-sensitivity factor, ms, of 1.8 % and 3.4 % for the MSY and MSA stations, respectively, for the TFE-coated glass filter tape. For the M8060 filter tape, Cf values of 2.50, 1.96 and 1.82 and ms values of 1.6 %, 3.0 % and 4.9 % for the BCN, MSY and MSA stations, respectively, were obtained. SSA variations also influenced the spectral dependence of C, which showed an increase with wavelength when SSA was above the site-dependent threshold. Below the SSA threshold, no statistically significant dependence of C on the wavelength was observed. For the measurement stations considered here, the wavelength dependence of C was to some extent driven by the presence of dust particles during Saharan dust outbreaks that had the potential to increase the SSA above the average values. At the mountaintop station, an omission of the wavelength dependence of the C factor led to an underestimation of the absorption Ångström exponent (AAE) by up to 12 %. Differences in the absorption coefficient determined from AE33 measurements at BCN, MSY and MSA of around 35 %–40 % can be expected when using the site-dependent experimentally obtained C value instead of the nominal C value. Due to the fundamental role that the SSA of the particles collected on the filter tape has in the multiple-scattering parameter C, we present a methodology that allows the recognition of the conditions upon which the use of a constant and wavelength-independent C is feasible.
Keywords: black carbon, aerosol absorption, filter photometer, artifact
Published: 01.10.2021; Views: 288; Downloads: 0
.pdf Fulltext (1,76 MB)

218.
219.
Testing the predictions of axisymmetric distribution functions of galactic dark matter with hydrodynamical simulations
Emmanuel Nezri, Julien Lavalle, Arturo Núñez-Castiñeyra, Mihael Petač, 2021, original scientific article

Abstract: Signal predictions for galactic dark matter (DM) searches often rely on assumptions regarding the DM phase-space distribution function (DF) in halos. This applies to both particle (e.g. p-wave suppressed or Sommerfeld-enhanced annihilation, scattering off atoms, etc.) and macroscopic DM candidates (e.g. microlensing of primordial black holes). As experiments and observations improve in precision, better assessing theoretical uncertainties becomes pressing in the prospect of deriving reliable constraints on DM candidates or trustworthy hints for detection. Most reliable predictions of DFs in halos are based on solving the steady-state collisionless Boltzmann equation (e.g. Eddington-like inversions, action-angle methods, etc.) consistently with observational constraints. One can do so starting from maximal symmetries and a minimal set of degrees of freedom, and then increasing complexity. Key issues are then whether adding complexity, which is computationally costy, improves predictions, and if so where to stop. Clues can be obtained by making predictions for zoomed-in hydrodynamical cosmological simulations in which one can access the true (coarse-grained) phase-space information. Here, we test an axisymmetric extension of the Eddington inversion to predict the full DM DF from its density profile and the total gravitational potential of the system. This permits to go beyond spherical symmetry, and is a priori well suited for spiral galaxies. We show that axisymmetry does not necessarily improve over spherical symmetry because the (observationally unconstrained) angular momentum of the DM halo is not generically aligned with the baryonic one. Theoretical errors are similar to those of the Eddington inversion though, at the 10-20% level for velocity-dependent predictions related to particle DM searches in spiral galaxies. We extensively describe the approach and comment on the results.
Keywords: galaxy dynamics, dark matter experiments, dark matter simulations, dark matter theory, cosmology, nongalactic astrophysics, astrophysics of galaxies, high energy physics
Published: 01.10.2021; Views: 295; Downloads: 17
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220.
Localisation and classification of gamma ray sources using neural networks
Guõlaugur Jóhannesson, Roberto Ruiz de Austri, Gabrijela Zaharijas, Sascha Caron, Boris Panes, Saptashwa Bhattacharyya, Chris van den Oetelaar, 2021, published scientific conference contribution

Abstract: With limited statistics and spatial resolution of current detectors, accurately localising and separating gamma-ray point sources from the dominating interstellar emission in the GeV energy range is challenging. Motivated by the challenges of the traditional methods used for the gamma-ray source detection, here we demonstrate the application of deep learning based algorithms to automatically detect and classify point sources, which can be applied directly to the binned Fermi-LAT data and potentially be generalised to other wavelengths. For the point source detection task, we use popular deep neural network structure U-NET, together with image segmentation, for precise localisation of sources, various clustering algorithms were tested on the segmented images. The training samples are based on the source properties of AGNs and PSRs from the latest Fermi-LAT source catalog, in addition to the background interstellar emission. Finally, we have created a more complex but robust training data generation exploiting full detector potential, increasing spatial resolution at the highest energies.
Keywords: gamma-rays, deep learning, computer vision
Published: 01.10.2021; Views: 267; Downloads: 7
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