arXiv subjects

Manuel Silva

Publications and source records attributed to Manuel Silva.

15 recordsLinked to original sources

arXiv2023

All for One, and One for All: UrbanSyn Dataset, the third Musketeer of Synthetic Driving Scenes

We introduce UrbanSyn, a photorealistic dataset acquired through semi-procedurally generated synthetic urban driving scenarios. Developed using high-quality geometry and materials, UrbanSyn provides pixel-level ground truth, including depth, semantic segmentation, and instance segmentation with object bounding boxes and occlusion degree. It complements GTAV and Synscapes datasets to form what we coin as the 'Three Musketeers'. We demonstrate the value of the Three Musketeers in unsupervised domain adaptation for image semantic segmentation. Results on real-world datasets, Cityscapes, Mapillary Vistas, and BDD100K, establish new benchmarks, largely attributed to UrbanSyn. We make UrbanSyn openly and freely accessible (www.urbansyn.org).

cs.CV↗

arXiv2023

Measurement of the Cosmic Neutrino Flux from the Southern Sky using 10 years of IceCube Starting Track Events

The measurement of a diffuse astrophysical neutrino flux using starting track events marks the first time IceCube has observed and subsequently measured the astrophysical diffuse flux using a dataset composed primarily of starting track events. Starting tracks combine an excellent angular and energy resolution. This enables us to take advantage of the self-veto effect in the southern sky reducing the atmospheric neutrino rate allowing us to detect astrophysical neutrinos to energies well below 100 TeV. We measure the astrophysical flux as $\phi^{per-flavor}_{Astro}=1.68^{+0.19}_{-0.22}$(at 100 TeV) and $\gamma_{Astro} = 2.58^{+0.10}_{-0.09}$ assuming a single power law flux. The astrophysical flux 90% sensitive energy range is 3 TeV to 500 TeV, extending IceCube's reach to the low energy astrophysical flux by an order of magnitude. A brief summary of tests performed to search for neutrinos from the galactic plane using this dataset is also provided. With this sample, we did not find statistically significant evidence for emission from the galactic plane. We then tested the impact of these galactic plane neutrinos on the isotropic diffuse flux, with at most 10% effect on the overall normalization and negligible impact to the spectral index.

astro-ph.HE↗

arXiv2023

Enhanced Starting Track Real-time Stream for IceCube

IceCube real-time alerts allow for rapid follow-up observations of likely astrophysical neutrino events, enabling searches for multi-messenger counterparts. The Enhanced Starting Track Real-time Stream (ESTReS) is a real-time extension of the Enhanced Starting Track Event Selection (ESTES), a high astrophysical purity muon-neutrino sample recently used by IceCube to measure the astrophysical diffuse flux. A set of computationally cheap cuts allows us to run a fast filter in seconds. This online filter selects about 100 events per day to be sent to Madison, WI via satellite where the full ESTES event selection is applied within minutes. Events that pass the final set of cuts (ESTReS + ESTES) will be sent out as real-time alerts to the broader astrophysical community. ESTReS's unique contribution to the current real-time alerts will be events in the southern sky in the 5 TeV - 100 TeV range. We expect about 10.3 events per year which average 50% astrophysical purity. In this talk I will report the status of the ESTReS alert stream in the context of the IceCube real-time program.

astro-ph.IM↗

arXiv2023

Low-Resource White-Box Semantic Segmentation of Supporting Towers on 3D Point Clouds via Signature Shape Identification

Research in 3D semantic segmentation has been increasing performance metrics, like the IoU, by scaling model complexity and computational resources, leaving behind researchers and practitioners that (1) cannot access the necessary resources and (2) do need transparency on the model decision mechanisms. In this paper, we propose SCENE-Net, a low-resource white-box model for 3D point cloud semantic segmentation. SCENE-Net identifies signature shapes on the point cloud via group equivariant non-expansive operators (GENEOs), providing intrinsic geometric interpretability. Our training time on a laptop is 85~min, and our inference time is 20~ms. SCENE-Net has 11 trainable geometrical parameters and requires fewer data than black-box models. SCENE--Net offers robustness to noisy labeling and data imbalance and has comparable IoU to state-of-the-art methods. With this paper, we release a 40~000 Km labeled dataset of rural terrain point clouds and our code implementation.

cs.CV↗

arXiv2021

Faint objects in motion: the new frontier of high precision astrometry

Sky survey telescopes and powerful targeted telescopes play complementary roles in astronomy. In order to investigate the nature and characteristics of the motions of very faint objects, a flexibly-pointed instrument capable of high astrometric accuracy is an ideal complement to current astrometric surveys and a unique tool for precision astrophysics. Such a space-based mission will push the frontier of precision astrometry from evidence of Earth-mass habitable worlds around the nearest stars, to distant Milky Way objects, and out to the Local Group of galaxies. As we enter the era of the James Webb Space Telescope and the new ground-based, adaptive-optics-enabled giant telescopes, by obtaining these high precision measurements on key objects that Gaia could not reach, a mission that focuses on high precision astrometry science can consolidate our theoretical understanding of the local Universe, enable extrapolation of physical processes to remote redshifts, and derive a much more consistent picture of cosmological evolution and the likely fate of our cosmos. Already several missions have been proposed to address the science case of faint objects in motion using high precision astrometry missions: NEAT proposed for the ESA M3 opportunity, micro-NEAT for the S1 opportunity, and Theia for the M4 and M5 opportunities. Additional new mission configurations adapted with technological innovations could be envisioned to pursue accurate measurements of these extremely small motions. The goal of this White Paper is to address the fundamental science questions that are at stake when we focus on the motions of faint sky objects and to briefly review instrumentation and mission profiles.

astro-ph.IM↗

arXiv2021

Searches for and Characterization of Astrophysical Neutrinos using Starting Track Events in IceCube

The IceCube Neutrino Observatory is a cubic kilometer-sized detector designed to detect neutrinos of astrophysical origin. However, muons created by cosmic rays interacting in the atmosphere pose a significant background for these astrophysical neutrinos particularly in the southern equatorial sky. Identifying neutrino events that start in the detector allows us to reduce the atmospheric muon component while retaining a high rate of starting neutrino events. The method presented today also rejects atmospheric neutrinos if they are accompanied by muons from the same cosmic ray shower, lowering the 50$\%$ purity threshold for astrophysical-to-atmospheric neutrinos from 100 TeV to ~10 TeV at declinations less than -25°. We use 10$\%$ (burn sample) of 9.5 years IceCube data to demonstrate the status of this dataset. We outline a planned measurement of the diffuse neutrino flux inclusive of theoretical and detector systematic uncertainties. In addition, we discuss searches for neutrino point sources and diffuse galactic plane neutrino emission in the Southern sky and plans to release high astrophysical-purity real-time alerts to the multi-messenger community.

astro-ph.HE↗

arXiv2020

On Liveness Enforcement of Distributed Petri Net Systems

This paper considers the liveness enforcement problem in a class of Petri nets (PNs) modeling distributed systems called Synchronized Sequential Processes (SSP). This class of PNs is defined as a set of mono-marked state machines (sequential machines, called also agents) cooperating in a distributed way through buffers. These buffers could model intermediate products in a production system or information channel in a healthcare system but they should be destination private to an agent. The designed controller for liveness enforcement should preserve this important property characteristic to the distributed systems. The approach in this paper is based on the construction of a control PN that is an abstraction of the relations of the T-semiflows and buffers. The control PN will evolve in parallel with the system, avoiding the firing of transitions that may lead the system to livelock. An algorithm to compute this control PN is presented. Moreover, in order to ensure the liveness of control PN, another algorithm is proposed allowing the firing of local T-semiflow in the correct proportion. Finally, an algorithm for guiding the system evolution is also proposed.

eess.SY↗

arXiv2019

Measurement of the Diffuse Muon Neutrino Flux using Starting Track Events in IceCube

IceCube measures the diffuse neutrino flux across several neutrino flavors and energy ranges. ESTES focuses on the measurement of the diffuse neutrino flux using high purity astrophysical muon neutrinos with energies above 1 TeV. We use the Enhanced Starting Track Event Selection dataset which selects for tracks starting within the IceCube fiducial volume. We employ a machine learning algorithm to help differentiate between tracks from atmospheric and astrophysical neutrinos. This produces a high purity diffuse neutrino sample that can provide valuable insight into the properties of the atmospheric and astrophysical diffuse neutrino spectrum. Using simulated neutrinos, we show the sensitivity for this measurement of the diffuse neutrino flux with ESTES.

astro-ph.HE↗

arXiv2019

Neutrino source searches and a realtime neutrino alert stream in the southern sky with IceCube starting tracks

IceCube analyses which look for an astrophysical neutrino signal in the southern sky face a large background of atmospheric muons and neutrinos created by cosmic ray air showers. By selecting starting events in the southern sky, atmospheric muons and neutrinos with accompanying muons are rejected, producing a sample with high astrophysical neutrino purity at lower energies than northern sky samples. Our new selection method looks for muon tracks from a neutrino interaction with a vertex contained inside the detector volume by using the good pointing resolution of the track morphology to create an event specific veto region in the detector to reject entering tracks. This starting track event selection has a high astrophysical neutrino purity above 10 TeV at declinations less than -30$^{\circ}$ which makes it ideal for use as a southern sky realtime neutrino alert stream. We will discuss neutrino point source searches using this event selection and look at the advantages of the starting track alert stream for multimessenger astrophysics.

astro-ph.HE↗

arXiv2019

Abelian Anti-Powers in Infinite Words

An abelian anti-power of order $k$ (or simply an abelian $k$-anti-power) is a concatenation of $k$ consecutive words of the same length having pairwise distinct Parikh vectors. This definition generalizes to the abelian setting the notion of a $k$-anti-power, as introduced in [G. Fici et al., Anti-powers in infinite words, J. Comb. Theory, Ser. A, 2018], that is a concatenation of $k$ pairwise distinct words of the same length. We aim to study whether a word contains abelian $k$-anti-powers for arbitrarily large $k$. S. Holub proved that all paperfolding words contain abelian powers of every order [Abelian powers in paper-folding words. J. Comb. Theory, Ser. A, 2013]. We show that they also contain abelian anti-powers of every order.

math.CO↗

arXiv2018

Anti-Powers in Infinite Words

In combinatorics of words, a concatenation of $k$ consecutive equal blocks is called a power of order $k$. In this paper we take a different point of view and define an anti-power of order $k$ as a concatenation of $k$ consecutive pairwise distinct blocks of the same length. As a main result, we show that every infinite word contains powers of any order or anti-powers of any order. That is, the existence of powers or anti-powers is an unavoidable regularity. Indeed, we prove a stronger result, which relates the density of anti-powers to the existence of a factor that occurs with arbitrary exponent. As a consequence, we show that in every aperiodic uniformly recurrent word, anti-powers of every order begin at every position. We further show that every infinite word avoiding anti-powers of order $3$ is ultimately periodic, while there exist aperiodic words avoiding anti-powers of order $4$. We also show that there exist aperiodic recurrent words avoiding anti-powers of order $6$.

cs.DM↗

arXiv2016

Monochromatic paths for the integers

Recall that van der Waerden's theorem states that any finite coloring of the naturals has arbitrarily long monochromatic arithmetic sequences. We explore questions about the set of differences of those sequences.

math.CO↗

arXiv2012

Power Challenges of Large Scale Research Infrastructures: the Square Kilometer Array and Solar Energy Integration; Towards a zero-carbon footprint next generation telescope

The Square Kilometer Array (SKA) will be the largest Global science project of the next two decades. It will encompass a sensor network dedicated to radioastronomy, covering two continents. It will be constructed in remote areas of South Africa and Australia, spreading over 3000Km, in high solar irradiance latitudes. Solar Power supply is therefore an option to power supply the SKA and contribute to a zero carbon footprint next generation telescope. Here we outline the major characteristics of the SKA and some innovation approaches on thermal solar energy Integration with SKA prototypes.

astro-ph.IM↗

arXiv2007

Binary linear forms over finite sets of integers

Let A be a finite set of integers. For a polynomial f(x_1,...,x_n) with integer coefficients, let f(A) = {f(a_1,...,a_n) : a_1,...,a_n \in A}. In this paper it is proved that for every pair of normalized binary linear forms f(x,y)=u_1x+v_1y and g(x,y)=u_2x+v_2y with integral coefficients, there exist arbitrarily large finite sets of integers A and B such that |f(A)| > |g(A)| and |f(B)| < |g(B)|.

math.NT↗

arXiv2006

Words avoiding repetitions in arithmetic progressions

Carpi constructed an infinite word over a 4-letter alphabet that avoids squares in all subsequences indexed by arithmetic progressions of odd difference. We show a connection between Carpi's construction and the paperfolding words. We extend Carpi's result by constructing uncountably many words that avoid squares in arithmetic progressions of odd difference. We also construct infinite words avoiding overlaps and infinite words avoiding arbitrarily large squares in arithmetic progressions of odd difference. We use these words to construct labelings of the 2-dimensional integer lattice such that any line through the lattice encounters a squarefree (resp. overlapfree) sequence of labels.

math.CO↗