196,921 research outputs found
Deep convolutional neural network to characterize transient noise in gravitational-wave detectors
No full textGravitational-wave detectors are affected by many noise sources,
including transient events called glitches, originating from instrumental or environmental
disturbances, that make the noise of a detector far from being stationary
and gaussian. Glitches affect data quality, and can mimic astrophysical signals or
even mask them. Therefore, it is fundamental to recognize these transients in order
to cluster them in families of similar morphology and investigate their origin. In
this paper we discuss the possibility of tackling this task with a deep convolutional
neural network
Image-based deep learning for classification of noise transients in gravitational wave detectors
No full textThe detection of gravitational waves has inaugurated the era of gravitational astronomy and opened new avenues for the multimessenger study of cosmic sources. Thanks to their sensitivity, the Advanced LIGO and Advanced Virgo interferometers will probe a much larger volume of space and expand the capability of discovering new gravitational wave emitters. The characterization of these detectors is a primary task in order to recognize the main sources of noise and optimize the sensitivity of interferometers. Glitches are transient noise events that can impact the data quality of the interferometers and their classification is an important task for detector characterization. Deep learning techniques are a promising tool for the recognition and classification of glitches. We present a classification pipeline that exploits convolutional neural networks to classify glitches starting from their time-frequency evolution represented as images. We evaluated the classification accuracy on simulated glitches, showing that the proposed algorithm can automatically classify glitches on very fast timescales and with high accuracy, thus providing a promising tool for online detector characterization
"Citoyens en quelque sorte" : classes d'âge et activité politique en Grèce ancienne : M. C. Giammarco Razzano, La vecchiaia di Solone. Età e politica nella città greca.
No full textCeccarelli Paola. "Citoyens en quelque sorte" : classes d'âge et activité politique en Grèce ancienne : M. C. Giammarco Razzano, La vecchiaia di Solone. Età e politica nella città greca.. In: Dialogues d'histoire ancienne, vol. 29, n°1, 2003. pp. 195-196
Numerical simulations for prediction of seismic ground motion amplification: 2D vs 3D comparison for natural reliefs and earth dams
No full textLocal site conditions (i.e., dynamic properties of subsurface and bedrock materials, surface and buried morphology) play an important role on seismic ground motion amplification. Therefore, their effects may become crucial in several geological/geotechnical systems such as earth dams and natural reliefs for selection of ground motion to be used in the analysis of engineering problems. These systems are usually studied based on 2D numerical analyses. However, due to the complexity of geomorphological and geotechnical situations, frequently coupled 3D soil-topography amplification analyses should be conducted to realistically assess the dynamic response.
In this research, large-scale numerical simulations are carried out with the finite difference computer code FLAC3D, that was used for both 2D and 3D analyses. Two case histories have been considered, the Palatino hill, a natural relief in the historical center of Rome, and the Angitola zoned dams in Southern Italy. In both cases visco-elastic linear analyses have been conducted considering models of increasing complexity, from homogeneous to heterogeneous ones with the inclusion of one or more additional layers, in order to distinguish between topographic and stratigraphic/valley amplification. In both cases Chang wavelet was used for input motion for three values of frequency (2Hz, 5Hz and 8Hz).
The comparison between the results of 2D and 3D analyses has been carried out in terms of maximum accelerations and/or displacement in representative points. The numerical analyses have been preceded by a calibration study, comparing the results of 2D and 3D numerical analyses with closed form solutions.
It is shown that 3D behavior can have a pronounced effect on the seismic response of the examined systems in terms of amplitude and shape of the acceleration/displacement profiles. In fact, 3D amplitudes can be much larger than 2D ones depending on the frequency of the input motion. The importance of vertical parasitic component of motion is highlighted, which again is frequency-dependent in that it increases with increasing frequency. For Angitola earth dams, the influence of narrow canyons in which the dams are built significantly contributes to the enhanced amplification of response, which is in agreement with the literature findings
Wavelet-based classification of transient signals for Gravitational Wave detectors
No full textThe detection of gravitational waves opened a new window on the cosmos. The Advanced LIGO and Advanced Virgo interferometers will probe a larger volume of Universe and discover new gravitational wave emitters. Characterizing these detectors is of primary importance in order to recognize the main sources of noise and optimize the sensitivity of the searches. Glitches are transient noise events that can impact the data quality of the interferometers and their classification is an important task for detector characterization. In this paper we present a classification method for short transient signals based on a Wavelet decomposition and de-noising and a classification of the extracted features based on XGBoost algorithm. Although the results show the accuracy is lower than that obtained with the use of deep learning, this method which extracts features while detecting signals in real time, can be configured as a fast classification system
Constellation Analysis of an Integrated AIS/Remote Sensing Spaceborne System for Ship Detection
No full textA Reduced Complexity MAP Receiver for Digital ISI Channels, with Application to HF Radio Links”, IEEE Workshop on Sig. Proc. Advances in Wireless Communications, SPAWC 2003, Rome, Italy
No full textAttuali prospettive in assicurazione vita delle neoplasie maligne trattate del distretto maxillo- facciale
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