Enhancing the significance of gravitational wave bursts through signal classification

The quest to observe gravitational waves challenges our ability to discriminate signals from detector noise. This issue is especially relevant for transient gravitational waves searches with a robust eyes wide open approach, the so called all- sky burst searches. Here we show how signal classification methods inspired by broad astrophysical characteristics can be implemented in all-sky burst searches preserving their generality. In our case study, we apply a multivariate analyses based on artificial neural networks to classify waves emitted in compact binary coalescences. We enhance by orders of magnitude the significance of signals belonging to this broad astrophysical class against the noise background. Alternatively, at a given level of mis-classification of noise events, we can detect about 1/4 more of the total signal population. We also show that a more general strategy of signal classification can actually be performed, by testing the ability of artificial neural networks in discriminating different signal classes. The possible impact on future observations by the LIGO-Virgo network of detectors is discussed by analysing recoloured noise from previous LIGO-Virgo data with coherent WaveBurst, one of the flagship pipelines dedicated to all-sky searches for transient gravitational waves

HBIM FOR THE SEISMIC VULNERABILITY ASSESSMENT OF TRADITIONAL BELL TOWERS

Abstract. The research proposes a novel and expeditious approach starting from direct and SfM (Structure from Motion) surveying up to H-BIM to provide a supporting tool to the knowledge of traditional bell towers, also useful for the seismic vulnerability assessment. The research draws on the possibility to enrich the H-BIM model with a semantic layer that takes into account the vulnerability indicators as defined in 2011 Italian Guidelines for the assessment and reduction of seismic risk of cultural heritage. Starting from 3D data survey, passing through the historical and constructive analysis, and the semantic classification of parts, the workflow foresaw the setting up of a semantic layer creating parameters to be assigned to each architectural component of the building and according an expeditious check-list which focuses on empirical knowledge of bell towers. This kind of information stored in the model could be very useful in situations that require particularly timely decision-making, such as in the case of calamitous events

Three Dimensional Dynamic Analysis of Alborz Dam with Asphalt and Clay Cores

Alborz rockfill dam with a clay core is under construction in North of Iran, an area of heavy rainfall. Because of the difficulties in the construction of a clay core in a wet area, an alternative for the watertight element (asphalt core) was considered. During the design of Alborz dam, a dynamic response analysis of the asphalt core was performed using two-dimensional modeling based on the equivalent linear method. Considering the shortage of study on the seismic behavior of asphalt core dams and also the high level of risk of earthquakes in Iran, it was necessary that the dynamic behavior of this dam was studied using three-dimensional models. In this study, the dynamic response of Alborz dam for both variants of clay and asphalt cores has been investigated and three-dimensional dynamic (non-linear) analyses have been carried out using the explicit finite-difference program, FLAC3-D, under various hazard levels of earthquakes (DBL and MCL). The results obtained included: time histories of the response acceleration, displacement, shear stress and shear strains are presented in this paper. The dynamic response of the dam with a clay core and asphalt core are compared with each other

Investigation of Dynamic Behavior of Asphalt Core Dams

In this research, dynamic behavior of a rockfill dam with asphalt-concrete core has been studied utilizing numerical models and centrifuge model tests with material parameters determined by laboratory tests including static and cyclic triaxial tests and also wave velocity measurements. The case study selected is the Meyjaran asphalt core dam, recently constructed in Northern Iran, with 60 m height and 180 m crest length. The seismic response analyses have been performed using a non-linear three dimensional finite difference software under various hazard levels of earthquake loadings. Their results showed that the induced shear strains in the asphalt core are less than 1% during an earthquake with amax=0.25g and the asphalt core remains watertight. Also, the small scale physical models of the asphalt core dam have been tested on centrifuge, under impact loading and response accelerations and induced deformations were recorded by instruments installed within and on the models. The recorded data and observations of the centrifuge model tested at 80g acceleration showed that the induced deformations in the asphalt core under an impact load with a large acceleration of 7.6 m/s2 were very small. Comparing the results of centrifuge tests with the results of numerical dynamic analyses of a prototype dam indicated that the numerical results corresponded well with the data recorded during centrifuge tests

Proyectos vinculados al recurso agua en comunidades originarias de la Provincia de Tucumán : el caso de la comunidad India Quilmes

Las comunidades originarias de la Provincia de Tucumán son 21 formalmente declaradas. Todas ellas están organizadas y reconocidas como parte del Estado Nacional a través de su personería jurídica y de un robusto marco legal y jurídico que las ubican como sujetos de Derechos. La Comunidad India Quilmes es una de ellas y está conformada por 14 comunidades de base, pueblos o parajes de la zona, las que suman alrededor de 630 familias. Dicha comunidad se ubica en el Valle de Yokavil, Departamento Tafí del Valle, en una zona de montaña con relieve quebrado y con zonas de marcado aislamiento. Los pobladores indígenas de Quilmes se dedican a la Agricultura y ganadería de tipo familiar y a la artesanía. El agua es una de las limitantes principales para la producción agrícola y ganadera de la zona. El presente trabajo busca identificar experiencias vinculadas al recurso agua en la zona, reflexionando acerca de la importancia del recurso en estos pueblos. El enfoque aplicado fue de tipo cualitativo, utilizando el estudio de caso como método de investigación. La muestra estuvo compuesta por Caciques de diferentes comunidades originarias, delegados de comunidades de base, productores, técnicos de proyectos e informantes calificados. Los resultados arrojan interesantes datos donde se identifican proyectos ejecutados e implementados en diversas comunidades, priorizando los mismos según importancia, alcance y necesidad de la población. También en este apartado surgen los efectos de estos proyectos desde diferentes dimensiones: económica, productiva y social y el impacto en las familias comuneras.There are approximately 21 original (native) communities in the Province of Tucumán. All of them are organized and have been recognized as part of the National State by their legal personality and a robust juridical and legal framework, which places them as subjects of Rights. The Quilmes Indian Community is one of them and is made up of 14 base communities or local villages of the area, which congregate about 630 families. This community is located in the Yokavil Valley, Tafí Department of the Valley, in a mountain area with broken land relief and areas of marked isolation. The indigenous inhabitants of Quilmes are dedicated in agriculture, family livestock, and crafts. Water is one of the main limits for agricultural production and livestock in the area. The present study seeks to identify water experiences in the area, and to reflect on the importance of the resource in these villages. A qualitative type approach was applied, using the case study as research method. The sample consisted of Chieftains (caciques) from different native communities, delegates from base communities, farmers, project technicians and qualified informants. The results show interesting data, identifying the projects implemented in different communities, and they are shown sorted by the importance, scope and need of the population. Also in this section, the effects of these projects arise from different dimensions (economic, productive and social) as well as the impact on community families.Fil: García Salemi, Ana C. Universidad Nacional de Tucumán.Fil: Ríos, Alejandro Daniel. Universidad Nacional de Tucumán.Fil: Ceconello, Marcos Mauricio. Universidad Nacional de Tucumán

Prospects for intermediate mass black hole binary searches with advanced gravitational-wave detectors

We estimated the sensitivity of the upcoming advanced, ground-based gravitational-wave observatories (the upgraded LIGO and Virgo and the KAGRA interferometers) to coalescing intermediate mass black hole binaries (IMBHB). We added waveforms modeling the gravitational radiation emitted by IMBHBs to detectors' simulated data and searched for the injected signals with the coherent WaveBurst algorithm. The tested binary's parameter space covers non-spinning IMBHBs with source-frame total masses between 50 and 1050 $\text{M}_{\odot}$ and mass ratios between $1/6$ and 1$\,$. We found that advanced detectors could be sensitive to these systems up to a range of a few Gpc. A theoretical model was adopted to estimate the expected observation rates, yielding up to a few tens of events per year. Thus, our results indicate that advanced detectors will have a reasonable chance to collect the first direct evidence for intermediate mass black holes and open a new, intriguing channel for probing the Universe over cosmological scales.Comment: 9 pages, 4 figures, corrected the name of one author (previously misspelled

Robust Chauvenet Outlier Rejection

Sigma clipping is commonly used in astronomy for outlier rejection, but the number of standard deviations beyond which one should clip data from a sample ultimately depends on the size of the sample. Chauvenet rejection is one of the oldest, and simplest, ways to account for this, but, like sigma clipping, depends on the sample's mean and standard deviation, neither of which are robust quantities: Both are easily contaminated by the very outliers they are being used to reject. Many, more robust measures of central tendency, and of sample deviation, exist, but each has a tradeoff with precision. Here, we demonstrate that outlier rejection can be both very robust and very precise if decreasingly robust but increasingly precise techniques are applied in sequence. To this end, we present a variation on Chauvenet rejection that we call "robust" Chauvenet rejection (RCR), which uses three decreasingly robust/increasingly precise measures of central tendency, and four decreasingly robust/increasingly precise measures of sample deviation. We show this sequential approach to be very effective for a wide variety of contaminant types, even when a significant -- even dominant -- fraction of the sample is contaminated, and especially when the contaminants are strong. Furthermore, we have developed a bulk-rejection variant, to significantly decrease computing times, and RCR can be applied both to weighted data, and when fitting parameterized models to data. We present aperture photometry in a contaminated, crowded field as an example. RCR may be used by anyone at https://skynet.unc.edu/rcr, and source code is available there as well.Comment: 62 pages, 48 figures, 7 tables, accepted for publication in ApJ