Search results for "NOISE"
showing 10 items of 1375 documents
On the analysis of the cat's pattern recognition system
1983
The objective of the paper is to determine in abstract terms the algorithms used by the cat detecting simple patterns and to quantify the contributions of the visual areas 17, 18, 19 for this task. The data incorporated in the algorithm are collected from behavioral experiments where the animals had to distinguish between two patterns. The patterns were superimposed with gaussian noise and the detection probability was measured. The resulting model describes pattern recognition in two steps: first extraction of features and second classification. The test of the validity of the model system was to predict the outcome of similar experiments but with different patterns. With the help of the m…
Split Bregman Method for Gravitational Wave Denoising
2014
This paper presents a progress report in our aim to develop a Total Variation algorithm for denoising of gravitational waves. These algorithms, are routinely employed in the context of image processing and they do not need any a priori information on the signals. We apply our method to two different types of numerically-simulated gravitational wave signals, namely burst produced from the core collapse of rotating stars and waveforms from binary black hole mergers, and present a preliminary assessment of its capabilities.
Bartlett formalism generating functions and Z-transforms in fluctuation and noise theory
1983
Abstract “La theorie des fonctions generatrices s'adapte elle meme et avec la plus grande generalite aux questions des probabilite les plus difficiles.” (Laplace, 1812) “An important part of probability theory consists of the derivation of the probability distribution of the sum of n random variables, each of which obeys a given probability law, and the development of asymptotic forms of these distributions valid for increasing n. Probability generating functions owe their dominant position to the simplification they permit to both problems. Their employment to obtain the successive moments of a probability distribution and to solve the difference equations of probability theory is ancillar…
Statistical physics: Some basic principles of fluctuation and noise theory
1983
Abstract Models have traditionally played a significant role in statistical mechanics. In view of the complexity of the system which statistical mechanics attempt to describe, this is not at all surprising. The study of simplified models has frequently revealed the underlying mathematical structure of many physical questions and in so doing the study of models has contributed directly to a clarification of several paradoxes which beset statistical mechanics. In this paper some of the models which appear to be useful for the discussion of non-equilibrium phenomena are examined in some detail. As usual these models are extremely simplified versions of the actual situations. It is, finally, as…
Investigating effects in GNSS station coordinate time series
2014
The vertical and horizontal displacements of the Earth can be measured to a high degree of precision using GNSS. Time series of Latvian GNSS station positions of both the EUPOS®-Riga and LatPos networks have been developed at the Institute of Geodesy and Geoinformation of the University of Latvia (LU GGI). In this study the main focus is made on the noise analysis of the obtained time series and site displacement identification. The results of time series have been analysed and distinctive behaviour of EUPOS®-Riga and LatPos station coordinate changes have been identified. The possible dependences of GNSS station coordinate distribution on EPN station problems, seismic activity of some area…
Effect of Local Geology on Ground Motion in the City of Palermo, Italy, as Inferred from Aftershocks of the 6 September 2002 Mw 5.9 Earthquake
2005
On 6 September 2002 a M w 5.9 earthquake occurred in the southern Tyrrhenian sea, 40 km off the coast of Palermo (Italy). In the days after the mainshock, eight temporary stations were installed in the city to record aftershocks on different geological formations. Seismograms of about 30 earthquakes with magnitude ≥2.8 are analyzed. The data analysis confirms the role of near-surface geology in causing locally significant variations of the ground-shaking level as already inferred by Guidoboni et al. (2003) from historical damage scenario studies. The largest spectral variations estimated through aftershock recordings result in a factor of 10 difference between stiff and soft sites, in frequ…
Microtremor Measurements in the City of Palermo, Italy: Analysis of the Correlation between Local Geology and Damage
2008
Abstract This study presents the results of 90 seismic ambient noise measurements in Palermo, the main city of Sicily (Italy). The dataset has been processed using the horizontal-to-vertical spectral ratio (HVNSR) technique and interpreted in terms of local geology, which is characterized by the presence of alluvial sediments of two riverbeds masked by urbanization since the seventeenth century. HVNSRs show significant variations in the study area: when the transition stiff to soft is crossed, a typical spectral peak appears in the HVNSRs, mostly in the frequency band 1–2 Hz, and exceeding a factor of 3 in amplitude. Using available information on subsurface geological structure, we compute…
The Urban Built Environment, Walking and Mental Health Outcomes Among Older Adults: A Pilot Study
2020
The benefits of walking in older age include improved cognitive health (e.g., mental alertness, improved memory functioning) and a reduced risk of stress, depression and dementia. However, research capturing the benefits of walking among older people in real-time as they navigate their world is currently very limited. This study explores cognitive health and well-being outcomes in older people as they walk in their local neighborhood environment. Residents from an independent living facility for older people (mean age 65, n = 11) walked from their home in two dichotomous settings, selected on the basis of significantly different infrastructure, varying levels of noise, traffic and percentag…
Auswirkungen von Umweltrisikofaktoren wie Lärm und Luftverschmutzung auf die psychische Gesundheit: Was wissen wir?
2020
ZusammenfassungImmer mehr Studien unterstreichen die Rolle von Lärm und Luftverschmutzung als bedeutsame Umweltrisikofaktoren. Ungeklärt ist, welche Einflüsse Lärm und Luftverschmutzung auf die psychische Gesundheit ausüben. Aktuelle Studienergebnisse zeigen, dass Umgebungslärm (vor allem Verkehrslärm) und verschiedene Bestandteile von Luftverschmutzung (vor allem Feinstaub) das Risiko für psychische Erkrankungen wie Depressionen, Angststörungen, Psychosen und Suizid erhöhen können. Pathophysiologische Mechanismen umfassen sowohl biologische (wie oxidativen Stress und Inflammation) als auch psychosoziale Faktoren (wie mentalen Stress). Umweltrisikofaktoren wie Lärm und Luftverschmutzung kön…
Implementation of a new adaptive algorithm using fuzzy cost function and robust to impulsive noise
2012
Adaptive filters are used in a wide range of applications such as noise cancellation, system identification, and prediction. One of the main problems for theses filters is the impulsive noise as it generates algorithm unstability. This work shows the development, simulation and hardware implementation of a new algorithm robust to impulsive noise. Hardware implementation becomes essential in many cases where a real time execution, reduced size, or low power system is needed. An efficient hardware architecture is proposed and different optimizations for size and speed are developed: no need for control state machine, reduced computation requirements due to simplifications, etc. Furthermore, t…