1,418 research outputs found
Low-latency analysis pipeline for compact binary coalescences in the advanced gravitational wave detector era
The multi-band template analysis (MBTA) pipeline is a low-latency coincident
analysis pipeline for the detection of gravitational waves (GWs) from compact
binary coalescences. MBTA runs with a low computational cost, and can identify
candidate GW events online with a sub-minute latency. The low computational
running cost of MBTA also makes it useful for data quality studies. Events
detected by MBTA online can be used to alert astronomical partners for
electromagnetic follow-up. We outline the current status of MBTA and give
details of recent pipeline upgrades and validation tests that were performed in
preparation for the first advanced detector observing period. The MBTA pipeline
is ready for the outset of the advanced detector era and the exciting prospects
it will bring.Comment: 18 pages, 10 figure
Training in the Use of Psychotherapy Outcome Assessment Measures at Psychology Internship Sites
American Psychological Association accredited psychology internship training programs (N = 407) were surveyed concerning their attitudes, beliefs, and practices with regard to outcome assessment measures. Results indicated that 47% of surveyed sites use outcome measures for assessment, and 66% used these measures for diagnostic purposes. In addition, 79% of respondents supported using outcome assessment measures to evaluate client progress, 61% supported training interns in the use of outcome assessment measures, and 87% felt outcome assessment measures would increase in importance in the future. The discrepancy between support for outcome assessment measures and actual use is discussed and recommendations provided
Target-depth estimation in active sonar
International audienceIn active sonar, the objectives are to detect, localize and classify an underwater target. Azimuth and range are often used in anti-submarine warfare to localize targets. The depth may also be used as the key tactical information for strategy purposes or as a good feature for target classification or discrimination. Two dimensional arrays as ank arrays, cylindrical arrays, and hullmounted arrays have access to elevation angles. Even linear towed arrays can give some information about the elevation using the different conical bearings measured when multipath propagation arises. In the context of long ranges and summer Mediterranean sound-speed profile (SSP), this paper presents a new target-depth estimation method, which uses elevation and arrival time measures from one sonar ping in a multipath environment. This method is based on ray back-propagation with a probabilistic approach. This localization algorithm minimizes the mean-squared error of elevation angles at the receiver and arrival times between a model and measures. This method is tested through Monte-Carlo simulations of classic active sonar scenarios and using experimental data from a real reduced-scaled tank. In active sonar, acoustic waves can take the same path on the way back or another path, so ray path combinations can occur. Our localization method discusses also about this ray identification, or how these combined acoustic paths were managed
Estimation de la vitesse d'une cible en mouvement par une méthode large bande et haute résolution
National audience– La connaissance de la réponse impulsionnelle d'un canal de propagation est nécessaire pour un grand nombre d'applications dans le domaine de l'acoustique sous-marine comme la communication, la localisation et détection sonar, la surveillance des mammifères marins... Cette réponse impulsionnelle nous informe sur les distorsions dues au canal, que subit un signal, et sur les déformations (décalage doppler non maîtrisé) engendrées par le mouvement relatif entre source et récepteur. Dans ce contexte, la connaissance du signal transmis permet d'estimer la vitesse apparente de chaque trajet de propagation à l'aide du plan d'ambiguïté large bande [1][2][3]. On sait qu'un filtrage basé sur les opérateurs de déformation temporelle et de plan d'ambiguïté large bande permet de séparer chaque trajet de façon précise afin de supprimer les interférences et d'estimer correctement la réponse impulsionnelle-avec le retard et le facteur de compression [4]. Dans cette étude, il est proposé une approche complémentaire pour estimer conjointement la vitesse et la distance d'une cible à faible vitesse (faible doppler) avec de bonnes résolutions. Les formes d'ondes émises sont des signaux codés tels que les signaux de Costas, les Binary Phase Shift Keying (BPSK) et les trains d'impulsions modulés linéairement en fréquence (Pulse Train Frequency Modulation, PTFM), dans un contexte haute résolution. Ces formes d'ondes étant larges bandes et ayant un fort produit BT, permettent ainsi d'utiliser un modèle d'écho prenant en compte la compression temporelle du signal dû à l'effet Doppler. Abstract – The knowledge of the impulse response of the propagation channel is required for many underwater applications such communication , sonar localization and detection, and marine mammals monitoring. This impulse response affects the signal and informs about the canal distortions, but also modifications (uncontrolled Doppler effects) caused by the relative motion between source and receiver. Knowing the emitted signal, the radial speed of each acoustic path can be estimated with the wideband ambiguity plan [1][2][3]. With warping operators based-filter and wideband ambiguity plan [4], acoustic paths can be accurately separated in order to remove interferences and estimate properly the impulse response-with the delay and the Doppler compression coefficient. This paper presents a complementary approach to jointly estimate the target distance and speed at low speed (low Doppler) with reasonable resolution. The emitted waveforms are 22-Welch-Costas signal, Binary Phase Shift Keying (BPSK) signal, and Pulse Train Frequency Modulation (PTFM) signal. Context is high resolution because signals have a large time-bandwidth product (high TB). For this reason, an echo model that accounts for a signal temporal compression (Doppler effect) can be used
Range, velocity and immersion estimation of a moving target in a water-filled tank with an active sonar system
International audience—The knowledge of the impulse response of the propagation channel is required for many underwater applications as communication, sonar detection and localization, marine mammals monitoring, etc. In the context of target classification, this impulse response informs about the relative motion between the source/receiver and the target through the Doppler effect. Knowing the emitted signal, the Doppler compression coefficient of each acoustic path can be estimated with the wideband ambiguity plan [1]–[3]. Warping operator based-filter and wideband ambiguity plan can be used to separate acoustic paths in order to remove interferences and estimate properly the target distance and speed [4]. This paper presents a complementary approach to jointly estimate the distance and speed of the target at a small speed with reasonable resolutions. The investigated sources are Binary Phase Shift Keying (BPSK), 22-Welch-Costas, and Pulse Train Frequency Modulation (PTFM) signal. Sources have a large Time-Bandwidth product (high TB) and provide high resolutions. For this reason, an echo model that takes into account a signal temporal compression (Doppler effect) can be used. A reduced-scale laboratory experiment was conducted to estimate the speed vector and depth of a moving target. Results for speed vectors are compared for the three different sources. A ray back propagation algorithm was used and results show correct estimation of the target depth
Autonomous feedback stabilization of a cavity-coupled spin oscillator
We report out-of-equilibrium stabilization of the collective spin of an
atomic ensemble through autonomous feedback by an optical cavity. For a
magnetic field applied at an angle to the cavity axis, dispersive coupling to
the cavity provides sensitivity to a combination of the longitudinal and
transverse spin. Coherent backaction from this measurement, conditioned by the
optical cavity susceptibility, stabilizes the collective spin state at an
arbitrary energy. The set point tracking and closed-loop gain spectrum of the
feedback system are characterized and found to agree closely with analytic
predictions
Analysis of parametric oscillatory instability in Fabry-Perot cavity with Gauss and Laguerre-Gauss main mode profile
We calculate the parametric instabilities in Fabry-Perot cavities of Advanced
VIRGO and LIGO interferometers with different main mode profiles. All unstable
combinations of elastic and Stokes modes both for the case with TEM00 and LG33
as a carriers are deduced.Comment: 11 pages, 3 figure
Calibration of the LIGO displacement actuators via laser frequency modulation
We present a frequency modulation technique for calibration of the
displacement actuators of the LIGO 4-km-long interferometric gravitational-wave
detectors. With the interferometer locked in a single-arm configuration, we
modulate the frequency of the laser light, creating an effective length
variation that we calibrate by measuring the amplitude of the frequency
modulation. By simultaneously driving the voice coil actuators that control the
length of the arm cavity, we calibrate the voice coil actuation coefficient
with an estimated 1-sigma uncertainty of less than one percent. This technique
enables a force-free, single-step actuator calibration using a displacement
fiducial that is fundamentally different from those employed in other
calibration methods.Comment: 10 pages, 5 figures, submitted to Classical and Quantum Gravit
Accurate calibration of test mass displacement in the LIGO interferometers
We describe three fundamentally different methods we have applied to
calibrate the test mass displacement actuators to search for systematic errors
in the calibration of the LIGO gravitational-wave detectors. The actuation
frequencies tested range from 90 Hz to 1 kHz and the actuation amplitudes range
from 1e-6 m to 1e-18 m. For each of the four test mass actuators measured, the
weighted mean coefficient over all frequencies for each technique deviates from
the average actuation coefficient for all three techniques by less than 4%.
This result indicates that systematic errors in the calibration of the
responses of the LIGO detectors to differential length variations are within
the stated uncertainties.Comment: 10 pages, 6 figures, submitted on 31 October 2009 to Classical and
Quantum Gravity for the proceedings of 8th Edoardo Amaldi Conference on
Gravitational Wave
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