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SN 2024acyl light curves
No full textWe present a photometric and spectroscopic analysis of the Type Ibn
supernova (SN) 2024acyl. It rises to an absolute magnitude peak of
M_o=-17.58±0.15mag in 10.6 days, and displays a rapid linear
post-peak light-curve decline in all bands (e.g.,
gamma0-60(V)=0.097±0.002mag/d), similar to most SNe Ibn. The
optical pseudobolometric light curve peaks at (3.5±0.8)x1042erg/s,
with a total radiated energy of (5.0±0.4)x1048erg. The spectra are
dominated by a blue continuum at early stages, with narrow P-Cygni HeI
lines and flash-ionisation emission lines of CIII, NIII, and HeII. The
P-Cygni HeI features gradually evolve and become emission-dominated
in late-time spectra. The H-alpha line is detected throughout the
entire spectral evolution, which indicates that the circumstellar
material (CSM) is helium-rich with some residual amount of hydrogen.
Our multiband light-curve modelling yields estimates of the ejecta
mass of Mej=0.49+0.11-0.09M☉, with a kinetic energy of
Ek=0.06+0.01-0.01x1051erg, and a 56Ni mass of
MNi=0.018M☉. The inferred CSM properties are characterised by
a mass of MCSM= 0.51 (+0.05/-0.04) M_sun, an inner radius of
R0=17.8+3.6-3.0AU, and a density
rhoCSM=(8.3+2.7-1.2)x10-12g/cm3. The multi-epoch spectra are
well reproduced by the CMFGEN/he4p0 model, corresponding to a He-ZAMS
mass of 4M☉ (H-ZAMS mass 18.11M☉, pre-SN mass
3.16M☉). These findings are consistent with a scenario of an SN
powered by ejecta-CSM interaction, originating from a low-mass helium
star that evolved within an interacting binary system where the CSM
with some residual hydrogen may originate from the mass-transfer
process. We also discuss an extreme scenario involving the possible
merger of a helium white dwarf. In addition, a channel of
core-collapse (CC) explosion of a late-type Wolf-Rayet (WR) star with
hydrogen (WNH), or a transitional star between an Of and a WR type
(e.g., an Ofpe/WN9 star) with fallback accretion, cannot be entirely
ruled out
Lakota
No full textThe thesis explores the theme of an apocalyptic future for civilization, questioning the nature and availability of food in the times to come. It provides a reflection on fundamental and higher human needs, identifying greed as the primary cause of disorder, imbalance, and chaos in the world. The work examines issues of food and hunger throughout history and humanity’s relationship with one of its most basic physiological needs. The current state of humanity is marked by two opposing conditions: global hunger on one side and excessive food consumption and overeating on the other. Insatiable demand and unethical fulfillment of human needs lead to a destructive future for both people and nature. The topic of food and hunger is analyzed through selected examples from visual and film art. A connection is established between the concept of the short film StarVation and the Biblical symbol of Famine, one of the Four Horsemen of the Apocalypse. The thesis follows the film’s development from initial concept, pre-production, and filming to production and editing across all stages of post-production.Delo raziskuje temo apokaliptične prihodnosti civilizacije in postavlja pod vprašaj hrano prihodnosti: kakšna in koliko je bo na voljo? Ponuja razmislek o osnovnih in višjih človekovih potrebah. Pohlep izpostavi kot glavni vzrok in krivca za nered, neravnovesje in kaos v svetu. Delo raziskuje vprašanje hrane in lakote skozi zgodovino in človekov odnos do ene od njegovih osnovnih fizioloških potreb. Trenutno stanje človeštva zaznamujeta dve nasprotji : svetovna lakota ter prekomerna poraba hrane in prenajedanje. Nenasitnost in neetično zadovoljevanje človekovih potreb vodita v uničujočo prihodnost za ljudi in naravo. Temo hrane in lakote analiziramo na izbranih primerih iz likovne in filmske umetnosti. Vzpostavimo povezavo med idejo kratkega filma “StarVation in svetopisemskim simbolom Lakote, enim od štirih jezdecev apokalipse. Sledimo nastajanju filma od razvoja ideje, predprodukcije, snemanja in produkcije ter oblikovanju filma v postprodukciji v vseh fazah
Multi-composition-exponential-modulo chaotification model
No full textThis work explores a chaotification technique that consists of the composition of exponential functions with offset boosting, in which the exponential term includes a seed function in its exponent. This architecture offers a high degree of design freedom, as several different map families can be designed, considering the number of compositions, the values of the control parameters, and the type of seed function. Based on this general family of maps, three different map examples are designed. Several analytical results are provided regarding the Lyapunov exponent expression and the existence of fixed points. The maps are then also studied numerically, through computation of cobweb, fixed point, bifurcation, and Lyapunov exponent diagrams. Interesting behaviors are observed, like the absence of fixed points and thus hidden attractors, as well as robust chaos. The maps are then successfully applied to the problem of pseudorandom bit generation. Overall, this family of maps gives very promising results for further studies
Photothermally triggered ▫▫ regeneration from monolithic silica-iron oxide sorbents
No full textElevated atmospheric CO2 disrupts the Earth’s carbon cycle, creating an urgent need for sustainable management strategies. Carbon Capture, Utilisation, and Storage (CCUS) technology can be seen as a potential solution but remains underutilised due to the high energy demand, particularly in desorption process. Conventional thermal and pressure swing methods require bulk heating or depressurisation of the sorbent chamber, leading to excessive energy consumption (1). Localised photothermal (PT) heating, with light that matches PT active material’s absorption maxima, can present a low-energy alternative for desorption (2). We prepared PT-active SiO2-Fe3O4 hybrid monoliths, where silica acts as the CO2 sorbent and Fe3O4 nanoparticles (IONPs) as the PT-active component. Silica monoliths were coated with different layer thickness of IONP, which was confirmed by SEM-EDXS and EDXS line profile analysis. N2 isotherms (BET analysis) showed that all the samples are hierarchically porous and that the hybrid monoliths samples display increased surface area compared to pristine silica. A similar trend is also observed in CO2 uptake where the CO2 capacity of the hybrid monoliths ≈1.77 mmol/g at 0°C and ≈0.96 mmol/g at 25°C. Additionally, thermally programmed desorption showed that for total CO2 regeneration, ≈100 °C needs to be reached. To evaluate the PT properties of the hybrid monoliths, PT experiments were conducted using different laser sources, i.e., 808nm (peak-off) and 447nm (peak-on). Surface temperatures were monitored by HD-IR camera and core temperatures by optical-fibre thermocouple. (Figure 1). We observed that illumination using the peak-on light leads to a higher surface temperature, compared to when using peak-off light. However, no notable difference in core temperatures was observed between peak-off and peak-on light conditions. This observation confirms a better energy efficiency when using peak-on light than peak-off at equal light powers. We also observed a non-linearity in the surface temperature with increasing layer in the case of peak-on illumination. This non-linearity revealed us that the PT effect in the case of monoliths is not only dependent on the layer thickness and light power but also on the concentration of PT nanoparticles in the layer and the penetration depth of the light. Moreover, further evidence for the effectiveness of peak-on illumination was provided by in-situ PT-triggered desorption, which achieved a 20% higher CO2 release during regeneration. This highlights the potential of peak targeted PT desorption approach for low-energy CCUS
