The detection and measurement of gravitational-waves from coalescing neutron-star binary systems is an important science goal for groundbased gravitational-wave detectors. In addition to emitting ...gravitational-waves at frequencies that span the most sensitive bands of the LIGO and Virgo detectors, these sources are also amongst the most likely to produce an electromagnetic counterpart to the gravitational-wave emission. A joint detection of the gravitational-wave and electromagnetic signals would provide a powerful new probe for astronomy. During the period between Sep 19 and Oct 20, 2010, the first low-latency search for gravitational-waves from binary inspirals in LIGO and Virgo data was conducted. Over the course of the science run, three gravitational-wave triggers passed all of the low-latency selection cuts. Of these, one was followed up by several of our observational partners. Analysis of the gravitational-wave data leads to an estimated false alarm rate of once every 6.4 days, falling far short of the requirement for a detection based solely on gravitational-wave data.
The NoEMi (Noise Frequency Event Miner) framework Acernese, F; Barone, F; Basti, A ...
Journal of physics. Conference series,
06/2012, Letnik:
363, Številka:
1
Journal Article, Conference Proceeding
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The data collected by a gravitational wave interferometer are inevitably affected by instrumental artefacts and environmental disturbances. In particular, for continuous gravitational wave (CW) ...studies it is important to detect narrow-band disturbances (the so-called "noise lines") during science runs, and to help scientists to identify and possibly remove or mitigate their sources. The NoEMi (Noise Frequency Event Miner) framework exploits some of the algorithms implemented for the CW search to identify, on a daily basis, the frequency lines observed in the Virgo science data and in a subset of the environmental sensors, looking for lines that match in frequency. A line tracker algorithm reconstructs the lines over time, and stores them in a database, which is made accesible via a web interface. We describe the workflow of NoEMi, providing examples of its use for the investigation of noise lines in past Virgo runs (VSR2, VSR3) and in the most recent run (VSR4).
The understanding of noise in interferometric gravitational wave detectors is fundamental in terms of both enabling prompt reactions in the mitigation of noise disturbances and in the establishment ...of appropriate data-cleaning strategies. Monitoring tools to perform online and offline noise analysis in areas such as transient signal detection, line identification algorithms and coherence are used to characterise the Virgo detector noise. In this paper, we describe the framework into which these tools are integrated - the Noise Monitor Application Programming Interface (NMAPI) - and provide examples of its application.
The Virgo gravitational wave detector is an interferometer (ITF) with 3km
arms located in Pisa, Italy. From July to October 2010, Virgo performed its
third science run (VSR3) in coincidence with the ...LIGO detectors. Despite
several techniques adopted to isolate the interferometer from the environment,
seismic noise remains an important issue for Virgo. Vibrations produced by the
detector infrastructure (such as air conditioning units, water
chillers/heaters, pumps) are found to affect Virgo's sensitivity, with the main
coupling mechanisms being through beam jitter and scattered light processes.
The Advanced Virgo (AdV) design seeks to reduce ITF couplings to environmental
noise by having most vibration-sensitive components suspended and in-vacuum, as
well as muffle and relocate loud machines. During the months of June and July
2010, a Guralp-3TD seismometer was stationed at various locations around the
Virgo site hosting major infrastructure machines. Seismic data were examined
using spectral and coherence analysis with seismic probes close to the
detector. The primary aim of this study was to identify noisy machines which
seismically affect the ITF environment and thus require mitigation attention.
Analyzed machines are located at various distances from the experimental halls,
ranging from 10m to 100m. An attempt is made to measure the attenuation of
emitted noise at the ITF and correlate it to the distance from the source and
to seismic attenuation models in soil.
In clinical routine, lower limb analysis relies on conventional X-ray (2D view) or computerised tomography (CT) Scan (lying position). However, these methods do not allow 3D analysis in standing ...position. The aim of this study is to propose a fast and accurate 3D-reconstruction-method based on parametric models and statistical inferences from biplanar X-rays with clinical measurements' (CM) assessment in standing position for a clinical routine use. For the reproducibility study, the 95% CI was under 2.7° for all lower limbs' angular measurements except for tibial torsion, femoral torsion and tibiofemoral rotation ( < 5°). The 95% CI were under 2.5 mm for lower limbs' lengths and 1.5 to 3° for the pelvis' CM. Comparisons between X-rays and CT-scan based 3D shapes in vitro showed mean differences of 1.0 mm (95% CI = 2.4 mm). Comparisons of 2D lower limbs' and 3D pelvis' CM between standing 'Shifted-Feet' and 'Non-Shifted-Feet' position showed means differences of 0.0 to 1.4°. Significant differences were found only for pelvic obliquity and rotation. The reconstruction time was about 5 min.
•Physical models to design the PV/T air systems are presented.•Electrical and thermal models are outlined to perform the performances of PV/T air-based systems.•An experimental validation of the ...discussed models is assessed in terms of thermal and electrical efficiencies.
Solar photovoltaic thermal (PV/T) systems have the capacity to become a key actor in the world's energy transition. The design of such systems requires the implementation and development of physical models, which can predict their thermal and electrical performances. In this paper, some of the main models for designing PV/T systems are developed. In fact, various configurations of equivalent-circuit models are presented to perform the electrical behavior of PV/T systems. Further, a Quasi-Steady Thermal Model (QSTM) is developed to forecast thermal performances. All reported models are validated based on the literature results. The efficiency analysis of developed models demonstrates that the good choice of equivalent-circuit model is substantial and varies according to the climatic changes. Limitations of certain electrical models have also been outlined and discussed. This work could be a guideline to researchers for the physical modelling of PV/T systems.
In recent years, a number of Photovoltaic/Thermal (PV/T) air designs were tested and investigated. However, it is challenging to assess whether a sophisticated design will be significantly more ...efficient than a basic one. This paper intends to outline different investigations conducted over the last years on photovoltaic-thermal technology. Findings from theoretical and experimental works, aiming to improve the efficiency of this technology regarding electrical and thermal power, are presented and discussed. Possible applications and future development of these technologies are also addressed.
Light-pulse atom interferometry in microgravity Stern, G.; Battelier, B.; Geiger, R. ...
The European physical journal. D, Atomic, molecular, and optical physics,
06/2009, Letnik:
53, Številka:
3
Journal Article
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We describe the operation of a light pulse interferometer using cold
87
Rb atoms in reduced gravity. Using a series of two Raman transitions induced by light pulses, we have obtained Ramsey fringes ...in the low gravity environment achieved during parabolic flights. With our compact apparatus, we have operated in a regime which is not accessible on ground. In the much lower gravity environment and lower vibration level of a satellite, our cold atom interferometer could measure accelerations with a sensitivity orders of magnitude better than the best ground based accelerometers and close to proven spaced-based ones.
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