Iskanje po repozitoriju

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Objavljeno v RUNG: 05.10.2021; Ogledov: 1341; Prenosov: 0
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Opis: 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.
Ključne besede: ognjenik, izbruh, astrofizika, gama žarki visokih energij, atmosfera, lidar
Objavljeno v RUNG: 04.10.2021; Ogledov: 2163; Prenosov: 0
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Opis: 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.
Ključne besede: oskrba z energijo, trajnostna energija, Mercator
Objavljeno v RUNG: 04.10.2021; Ogledov: 1667; Prenosov: 0
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Opis: 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.
Ključne besede: Avgust Černigoj, slovenski konstruktivizem, Tržaški konstruktivistični ambient, revija Tank, El Lissitzky, Edvard Stepančič, instalacija v umetnosti, abstraktni ambient, zenitizem, dadaizem
Objavljeno v RUNG: 04.10.2021; Ogledov: 1733; Prenosov: 0
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Opis: 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.
Ključne besede: black carbon, aerosol absorption, filter photometer, artifact
Objavljeno v RUNG: 01.10.2021; Ogledov: 1945; Prenosov: 0
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