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3. Localisation and classification of gamma ray sources using neural networksChris van den Oetelaar, Saptashwa Bhattacharyya, Boris Panes, Sascha Caron, Gabrijela Zaharijas, Roberto Ruiz de Austri, Guõlaugur Jóhannesson, 2021, objavljeni znanstveni prispevek na konferenci Opis: 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.
Ključne besede: gamma-rays, deep learning, computer vision
Objavljeno v RUNG: 01.10.2021; Ogledov: 1658; Prenosov: 42
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4. Molekularna karakterizacija lebdećih čestica slobodne troposfere sa Opservatorija Pico planineKatja Džepina, Claudio Mazzoleni, Paulo Fialho, Swarup China, B. Zhang, R. Chris Owen, D. Helmig, J. Hueber, Sumit Kumar, J. A. Perlinger, 2017, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Long-range transported free tropospheric aerosol was sampled at the PMO (38°28’15’’N, 28°24’14’’W; 2225 m amsl) on Pico Island of the Azores in the North Atlantic. Filter-collected aerosol during summer 2012 was analysed for organic and elemental carbon, and inorganic ions. The average aerosol ambient concentration was 0.9 µg m-3. Organic aerosol contributed the majority of mass (57%), followed by sulphate (21%) and nitrate (17%). Filter-collected aerosol was positively correlated with on-line aerosol measurements of black carbon, light scattering and number concentration. Water-soluble organic compounds (WSOC) from 9/24 and 9/25 samples collected during a pollution event were analysed with ultrahigh-resolution FT-ICR MS. FLEXPART analysis showed the air masses were very aged (>12 days). ~4000 molecular formulas were assigned to each of the mass spectra between m/z 100-1000. The majority of the assigned molecular formulas have unsaturated structures with CHO and CHNO elemental compositions. WSOC have an average O/C of ~0.45, relatively low compared to O/C of other aged aerosol, which might be the result of evaporation and fragmentation during long-range transport. The increase in aerosol loading during 9/24 was linked to biomass burning emissions from North America by FLEXPART and MODIS fire counts. This was confirmed with WSOC biomass burning markers and with the morphology and mixing state of particles as determined by SEM. The presence of markers characteristic of aqueous-phase reactions of biomass burning phenolic species suggests that the aerosol collected at Pico had undergone cloud processing. The air masses on 9/25 were more aged (~15 days) and influenced by marine emissions, as indicated by organosulphates and species characteristic for marine aerosol (e.g. fatty acids). The change in air masses for the two samples was corroborated by the changes in ozone, ethane, propane, morphology of particles, as well as by FLEXPART. In this presentation we will presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at the PMO.
Ključne besede: Atmospheric aerosol, Free troposphere, Mass spectrometry, Pico mountain observatory
Objavljeno v RUNG: 26.05.2021; Ogledov: 2616; Prenosov: 0
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5. Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory : a case study with a long-range transported biomass burning plumeKatja Džepina, Claudio Mazzoleni, Paulo Fialho, Swarup China, Bo Zhang, R. Chris Owen, D. Helmig, J. Hueber, Sumit Kumar, J. A. Perlinger, 2015, izvirni znanstveni članek Opis: Free tropospheric aerosol was sampled at the
Pico Mountain Observatory located at 2225 m above mean
sea level on Pico Island of the Azores archipelago in the
North Atlantic. The observatory is located ∼ 3900 km east
and downwind of North America, which enables studies
of free tropospheric air transported over long distances.
Aerosol samples collected on filters from June to October
2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 µg m−3
. On average, organic aerosol components represent the largest mass fraction of the total measured aerosol (60 ± 51 %), followed by
sulfate (23 ± 28 %), nitrate (13 ± 10 %), chloride (2 ± 3 %),
and elemental carbon (2 ± 2 %). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and
9/25) collected consecutively during a pollution event were
analyzed using ultrahigh-resolution electrospray ionization
Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned
to each of the mass spectra in the range of m/z 100–1000.
The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled
air masses were very aged (average plume age > 12 days).
These aged aerosol WSOM compounds had an average O /C
ratio of ∼ 0.45, which is relatively low compared to O /C
ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to
biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM
and with the morphology and mixing state of particles as
determined by scanning electron microscopy. The presence
of markers characteristic of aqueous-phase reactions of phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses of 9/25 were
more aged and influenced by marine emissions, as indicated
by the presence of organosulfates and other species characteristic of marine aerosol. The change in the air masses for
the two samples was corroborated by the changes in ethane,
propane, and ozone, morphology of particles, as well as by
the FLEXPART retroplume simulations. This paper presents
the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere
remote location and provides evidence of low oxygenation
after long-range transport. We hypothesize this is a result of
the selective removal of highly aged and polar species during long-range transport, because the aerosol underwent a
combination of atmospheric processes during transport facilitating aqueous-phase removal (e.g., clouds processing) and
fragmentation (e.g., photolysis) of components.
Ključne besede: organic aerosol, ultrahigh-resolution FT-ICR MS, electron microscopy, remote marine atmosphere, Pico Mountain Observatory
Objavljeno v RUNG: 11.04.2021; Ogledov: 2288; Prenosov: 0
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6. Ice cloud formation potential by free tropospheric particles from long-range transport over the Northern Atlantic OceanSwarup China, Peter A. Alpert, Bo Zhang, Simeon K. Schum, Katja Džepina, Kendra Wright, R. Chris Owen, Paulo Fialho, Lynn R. Mazzoleni, Claudio Mazzoleni, 2017, izvirni znanstveni članek Opis: Long-range transported free tropospheric particles can play a significant role on heterogeneous ice nucleation. Using optical and electron microscopy we examine the physicochemical characteristics of ice nucleating particles (INPs). Particles were collected on substrates from the free troposphere at the remote Pico Mountain Observatory in the Azores Islands, after long-range transport and aging over the Atlantic Ocean. We investigate four specific events to study the ice formation potential by the collected particles with different ages and transport patterns. We use single-particle analysis, as well as bulk analysis to characterize particle populations. Both analyses show substantial differences in particle composition between samples from the four events; in addition, single-particle microscopy analysis indicates that most particles are coated
by organic material. The identified INPs contained mixtures of dust, aged sea salt and soot, and organic material acquired either at the source or during transport. The temperature and relative humidity (RH) at which ice formed, varied only by 5% between samples, despite differences in particle composition, sources, and transport patterns. We hypothesize that this small variation in the onset RH may be due to the coating material on the particles. This study underscores and motivates the need to further investigate how long-range transported and atmospherically aged free tropospheric particles impact ice cloud formation.
Ključne besede: atmospheric aerosols, ice nucleating particles, long-range transport, optical microscopy, electron microscopy, Pico Mountain Observatory
Objavljeno v RUNG: 11.04.2021; Ogledov: 2307; Prenosov: 133
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7. Innovation on European and social terms for a solidarity among disciplines2020, radijska ali televizijska oddaja, podkast, intervju, novinarska konferenca Ključne besede: innovation, solidarity, future of work, art thinking, Social Europe, workers rights, responsibility, interdisciplinary
Objavljeno v RUNG: 25.11.2020; Ogledov: 2402; Prenosov: 27
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8. A map-matching algorithm dealing with sparse cellular fingerprint observationsAndrea Dalla Torre, Paolo Gallo, Donatella Gubiani, Chris Marshall, Angelo Montanari, Federico Pittino, Andrea Viel, 2019, izvirni znanstveni članek Opis: The widespread availability of mobile communication makes mobile devices a resource for the collection of data about mobile infrastructures and user mobility. In these contexts, the problem of reconstructing the most likely trajectory of a device on the road network on the basis of the sequence of observed locations (map-matching problem) turns out to be particularly relevant. Different contributions have demonstrated that the reconstruction of the trajectory of a device with good accuracy is technically feasible even when only a sparse set of GNSS positions is available. In this paper, we face the problem of coping with sparse sequences of cellular fingerprints. Compared to GNSS positions, cellular fingerprints provide coarser spatial information, but they work even when a device is missing GNSS positions or is operating in an energy saving mode. We devise a new map-matching algorithm, that exploits the well-known Hidden Markov Model and Random Forests to successfully deal with noisy and sparse cellular observations. The performance of the proposed solution has been tested over a medium-sized Italian city urban environment by varying both the sampling of the observations and the density of the fingerprint map as well as by including some GPS positions into the sequence of fingerprint observations.
Ključne besede: Map-matching algorithm, trajectory, cellular fingerprint, Hidden Markov Model
Objavljeno v RUNG: 11.06.2019; Ogledov: 3316; Prenosov: 97
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9. Map matching with sparse cellular fingerprint observationsAndrea Viel, Donatella Gubiani, Paolo Gallo, Angelo Montanari, Andrea Dalla Torre, Federico Pittino, Chris Marshall, 2018, objavljeni znanstveni prispevek na konferenci Ključne besede: map matching, fingerprint, trajectories
Objavljeno v RUNG: 09.12.2018; Ogledov: 3615; Prenosov: 0
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10. Dealing with network changes in cellular fingerprint positioning systemsAndrea Viel, Paolo Gallo, Angelo Montanari, Donatella Gubiani, Andrea Dalla Torre, Federico Pittino, Chris Marshall, 2017, objavljeni znanstveni prispevek na konferenci Opis: Besides being a fundamental infrastructure for communication, cellular networks are exploited for positioning through signal fingerprinting. Maintaining the fingerprint database consistent and up-to-date is a challenging task in many fingerprint positioning systems, e.g., in those populated by a crowd-sourcing effort. To this end, detecting and tracking the changes in the configurations of cellular networks over time is recognized as a relevant problem. In this paper, we show that to cope with this problem we can successfully exploit information provided by Timing Advance (TA). As a by-product, we prove that TA can improve the fingerprint candidate selection phase, reducing the number of fingerprints to provide as input to positioning algorithms. The effectiveness of the proposed improvements has been tested on a fingerprint positioning system with a large fingerprint dataset collected over a period of 2 years.
Ključne besede: fingerprint positioning systems, cellular communication networks, network changes
Objavljeno v RUNG: 13.06.2018; Ogledov: 3898; Prenosov: 0
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