scholarly journals Application of Spatio-Temporal Spectral Analysis for Detection of Seismic Waves in Gravitational-Wave Interferometer

Galaxies ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 50
Author(s):  
Robert Szymko ◽  
Mateusz Denys ◽  
Tomasz Bulik ◽  
Bartosz Idźkowski ◽  
Adam Kutynia ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Seismic Waves ◽  
Noise Suppression ◽  
Frequency Range ◽  
Noise Sources ◽  
Seismic Sensors ◽  
Gravitational Wave Interferometer ◽  
Length Direction ◽  
Spatio Temporal ◽  
Measurement Period

Mixed spatio–temporal spectral analysis was applied for the detection of seismic waves passing through the west–end building of the Virgo interferometer. The method enables detection of a passing wave, including its frequency, length, direction, and amplitude. A thorough analysis aimed at improving sensitivity of the Virgo detector was made for the data gathered by 38 seismic sensors, in the two–week measurement period, from 24 January to 6 February 2018, and for frequency range 5–20 Hz. Two dominant seismic–wave frequencies were found: 5.5 Hz and 17.1 Hz. The presented method can be applied for a better understanding of the interferometer seismic environment, and by identifying noise sources, help the noise–hunting and mitigation work that eventually leads to interferometer noise suppression.

scholarly journals Characterization of the seismic field at Virgo and improved estimates of Newtonian-noise suppression by recesses

2021 ◽  
Author(s):  
Ayatri Singha ◽  
Stefan Hild ◽  
Jan Harms ◽  
Maria Concetta Tringali ◽  
Irene Fiori ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Rayleigh Waves ◽  
Seismic Waves ◽  
Noise Suppression ◽  
Low Frequency ◽  
Seismic Sources ◽  
Frequency Sensitivity ◽  
Gravitational Forces ◽  
Fold Reduction

Abstract Fluctuations of gravitational forces cause so-called Newtonian noise (NN) in gravitational-wave (GW) detectors which is expected to limit their low-frequency sensitivity in upcoming observing runs. Seismic NN is produced by seismic waves passing near a detector's suspended test masses. It is predicted to be the strongest contribution to NN. Modeling this contribution accurately is a major challenge. Arrays of seismometers were deployed at the Virgo site to characterize the seismic field near the four test masses. In this paper, we present results of a spectral analysis of the array data from one of Virgo's end buildings to identify dominant modes of the seismic field. Some of the modes can be associated with known seismic sources. Analyzing the modes over a range of frequencies, we provide a dispersion curve of Rayleigh waves. We find that the Rayleigh speed in the NN frequency band 10\,Hz--20\,Hz is very low ($\lesssim$100\,m/s), which has important consequences for Virgo's seismic NN. Using the new speed estimate, we find that the recess formed under the suspended test masses by a basement level at the end buildings leads to a 10 fold reduction of seismic NN.

Effects of spinal cord transection on sympathetic discharge in decerebrate-unanesthetized cats

1989 ◽  
Vol 257 (6) ◽  
pp. R1506-R1511 ◽  
Author(s):  
L. C. Weaver ◽  
R. D. Stein
Keyword(s):  
Blood Pressure ◽  
Spinal Cord ◽  
Heart Rate ◽  
Spectral Analysis ◽  
Spinal Cord Transection ◽  
Renal Nerves ◽  
Frequency Range ◽  
Renal Nerve ◽  
Sympathetic Discharge ◽  
Nerve Discharge

Previous experiments in our laboratory have shown that discharge of splenic, mesenteric, and splanchnic nerves is well maintained after spinal cord transection in chloralose-anesthetized cats (8, 9, 11). The primary purpose of this investigation was to determine if maintained sympathetic discharge could be observed after spinal transection in the absence of chloralose anesthesia. In cats anesthetized with alphaxalone-alphadolone, changes in splanchnic discharge, blood pressure, and heart rate caused by decerebration and removal of the forebrain were observed. This procedure decreased blood pressure, increased heart rate, and had no immediate effect on sympathetic discharge or its rhythm (assessed by power density spectral analysis). One hour after decerebration and termination of anesthesia, splanchnic discharge had increased by approximately 36%. Next, effects of spinal cord transection on discharge of splanchnic, mesenteric, and renal nerves were observed in the decerebrate-unanesthetized cats. Splanchnic discharge decreased by 50%, mesenteric nerve discharge was unchanged, and renal nerve discharge decreased by 97%. Therefore, splanchnic nerve discharge was not as well maintained in decerebrate-unanesthetized cats as it had been in chloralose-anesthetized animals, and the remaining splanchnic discharge appeared to affect mesenteric nerves preferentially. Finally, spectral analysis of the splanchnic discharge demonstrated that before cord transection, most of the signal was in the 0- to 6-Hz frequency range, whereas after transection the proportion of signal in this frequency range was significantly reduced and the proportion in higher frequencies (7-25 Hz) was significantly increased. This loss of low-frequency rhythmicity is consistent with findings in our previous studies in chloralose-anesthetized cats.

scholarly journals Quantitative EEG evaluation in patients with acute encephalopathy

2013 ◽  
Vol 71 (12) ◽  
pp. 937-942 ◽  
Author(s):  
Aline Souza Marques da Silva Braga ◽  
Bruno Della Ripa Rodrigues Assis ◽  
Jamil Thiago Rosa Ribeiro ◽  
Patricia Maria Sales Polla ◽  
Breno Jose Hulle Pereira ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Spectral Power ◽  
Quantitative Eeg ◽  
Acute Encephalopathy ◽  
Frequency Range ◽  
Alpha Frequency ◽  
Outcome Group ◽  
Spectral Peaks ◽  
Group A ◽  
Group B

Objective To investigate the use of quantitative EEG (qEEG) in patients with acute encephalopathies (AEs) and EEG background abnormalities. Method Patients were divided into favorable outcome (group A, 43 patients) and an unfavorable outcome (group B, 5 patients). EEGLAB software was used for the qEEG analysis. A graphic of the spectral power from all channels was generated for each participant. Statistical comparisons between the groups were performed. Results In group A, spectral analysis revealed spectral peaks (theta and alpha frequency bands) in 84% (38/45) of the patients. In group B, a spectral peak in the delta frequency range was detected in one patient. The remainder of the patients in both groups did not present spectral peaks. Statistical analysis showed lower frequencies recorded from the posterior electrodes in group B patients. Conclusion qEEG may be useful in the evaluations of patients with AEs by assisting with the prognostic determination.

scholarly journals Spatio-temporal change assessment using normalize difference vegetative index and spectral analysis techniques for vegetation cover on Wadi Auranah

2014 ◽  
Vol 16 (5) ◽  
pp. 955-965
Keyword(s):  
Spectral Analysis ◽  
Land Cover ◽  
Temporal Change ◽  
Treated Wastewater ◽  
Change Assessment ◽  
Field Assessment ◽  
Normalize Difference Vegetative Index ◽  
Increasing Trend ◽  
Geologic Map ◽  
Spatio Temporal

<div> <p>Wadi Auranah is one of the potential wadis in respect of land use, located on the western shield (Hijaz escarpment) of Saudi Arabia. A spatio-temporal change assessment of this wadi (valley) was conducted with the help of landsat data. The results of the spectral analysis and NDVI for vegetation changes assessment reveals a continuous increasing trend of land cover biomass in specific parts of the wadi. Geological review of geologic map supports soil fertility. It is observed from field assessment of the study area that has potential for more land more to be cultivated. About 73 km<sup>2</sup> of vegetation land cover has been increased in the last 20 years. Treated wastewater is the main source of water supply that is used for afforestation and cultivation purpose.</p> </div> <p>&nbsp;</p>

scholarly journals Urban Distributed Acoustic Sensing Using In-Situ Fibre Beneath Bern, Switzerland

2020 ◽  
Author(s):  
Krystyna Smolinski ◽  
Patrick Paitz ◽  
Daniel Bowden ◽  
Pascal Edme ◽  
Felix Kugler ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Seismic Waves ◽  
Velocity Structure ◽  
Road Traffic ◽  
Hazard Analysis ◽  
Noise Sources ◽  
Acoustic Sensing ◽  
Wide Range ◽  
Distributed Acoustic Sensing

&lt;p&gt;Anticipating the risks natural hazards pose to an urban environment requires an understanding of the shallow Earth structure of the region. While urban infrastructure often hinders the deployment of a traditional seismic array, Distributed Acoustic Sensing (DAS) technology facilitates the use of existing telecommunication fibre-optic cables for seismic observation, with spatial resolution down to the metre scale.&lt;/p&gt;&lt;p&gt;Through collaboration with the SWITCH foundation, we were able to use existing, in-situ fibres beneath Bern, Switzerland for seismic data acquisition over two weeks, covering a distance of 6 km with a spatial resolution of 2 m. This allowed for not only real-time visualisation of anthropogenic noise sources (e.g. road traffic), but also of the propagation of resulting seismic waves.&lt;/p&gt;&lt;p&gt;Data is analysed in the time and frequency domain to explore the range of signals captured and to assess the consistency of data quality along the cable. The local velocity structure can be constrained using both noise correlations and deterministic signals excited by traffic.&lt;/p&gt;&lt;p&gt;Initial results reveal the ability of DAS to capture signals over a wide range of frequencies and distances, and show promise for utilising urban DAS data to perform urban seismic tomography and hazard analysis.&lt;/p&gt;

scholarly journals Identification and Removal of Non-acoustic Noise in Towed Array Sonar Using F-Κ Transform for Enhanced Torpedo Detection

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Vibration Isolation ◽  
Acoustic Noise ◽  
Detection System ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Noise Sources ◽  
Towed Array ◽  
Spatio Temporal ◽  
Towed Arrays

Low frequency passive towed array sonar is an essential component in a torpedo detection system for surface ships. Compact towed arrays are used for torpedo detection and they will be towed at higher towing speeds compared to conventional towed array sonars used for surveillance. Presence of non-acoustic noise in towed array sensors at higher towing speeds degrades torpedo detection capability at lower frequencies. High wavenumber mechanical vibrations are induced in the array by vortex shedding associated with hydrodynamic flow over the array body and cable scope. These vibrations are known to couple into the hydrophone array as nonacoustic noise sources and can impair acoustic detection performance, particularly in the forward end fire direction. Lengthy mechanical vibration isolation modules can isolate vibration induced noise in towed arrays, but this is not recommended in a towed array which is towed at high speeds as it will increase the drag and system complexity. An algorithm for decomposing acoustic and non-acoustic components of signals received at sensor level using well known frequency-wavenumber transform (F-K transform) is presented here. Frequency-wavenumber diagrams can be used for differentiating between acoustic and non-acoustic signals. An area of V shape is identified within the F-K spectrum where acoustic energy is confined. Energy outside this V will highlight non-acoustic energy. Enhanced simultaneous spatio-temporal and spatio-amplitude detection is possible with this algorithm. Performance of this algorithm is validated through simulation and experimental data.

scholarly journals Reducing the harmful effects of noise on the human environment. Sound insulation of industrial skeleton enclosures in the 10–40 kHz frequency range

2020 ◽  
Vol 18 (2) ◽  
pp. 1451-1463
Author(s):  
Witold Mikulski
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sheet Steel ◽  
Pressure Level ◽  
Sound Insulation ◽  
Frequency Range ◽  
Noise Sources ◽  
Human Environment ◽  
Absorbing Material ◽  
Acoustic Enclosures

Abstract Purpose The purpose of the research is to work out a method for determining the sound insulation of acoustic enclosures for industrial sources emitting noise in the frequency range of 10–40 kHz and apply the method to measure the sound insulation of acoustic enclosures build of different materials. Methods The method is developed by appropriate adaptation of techniques applicable currently for sound frequencies of up to 10 kHz. The sound insulation of example enclosures is determined with the use of this newly developed method. Results The research results indicate that enclosures (made of polycarbonate, plexiglass, sheet aluminium, sheet steel, plywood, and composite materials) enable reducing the sound pressure level in the environment for the frequency of 10 kHz by 19–25 dB with the reduction increasing to 40–48 dB for the frequency of 40 Hz. The sound insulation of acoustic enclosures with a sound-absorbing material inside reaches about 38 dB for the frequency of 10 kHz and about 63 dB for the frequency of 40 kHz. Conclusion Some pieces of equipment installed in the work environment are sources of noise emitted in the 10–40 kHz frequency range with the intensity which can be high enough to be harmful to humans. The most effective technical reduction of the associated risks are acoustic enclosures for such noise sources. The sound pressure level reduction obtained after provision of an enclosure depends on its design (shape, size, material, and thickness of walls) and the noise source frequency spectrum. Realistically available noise reduction values may exceed 60 dB.

Analysis of Glacier Run-Off and Meteorological Observations

1972 ◽  
Vol 11 (63) ◽  
pp. 303-318 ◽  
Author(s):  
Gudmundur Gudmundsson ◽  
Guttormur Sigbjarnarson
Keyword(s):  
Spectral Analysis ◽  
Linear Relationship ◽  
Impulse Response ◽  
Linear Models ◽  
Time Lag ◽  
Diurnal Variations ◽  
Frequency Range ◽  
Western Margin ◽  
Run Off ◽  
Meteorological Observations

Abstract Linear models of the relationships between meteorological observations and the flow of river Tungnaá at the western margin of glacier Vatnajökull were investigated by means of spectral analysis and estimation of the impulse response. Most of the variation of Tungnaá is confined to the lowest frequencies and the diurnal variations. The temperature has most effect on the rapid variations around 1 cycle/day whereas the largest coherences with the precipitation are in the lowest frequencies. The wind explains over 20% of the variations in the frequency range from 0–1 cycle/day, but this is partly due to its coherence with the precipitation. The time lag between changes in the temperature and the river is about 2 h, but the time lag between precipitation and the river is longer. Analysis of longer records of daily observations from Ϸjórsá shows that the coherence of the run-off and temperature increases at frequencies too low to be estimated from these data. At frequencies over 1 cycle/day most of the observed variations of the river cannot be explained by means of a linear relationship with the meteorological series.

scholarly journals Solving Noise Pollution Issue Using Plenum Window with Perforated Thin Box

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 614
Author(s):  
Hsiao Mun Lee ◽  
Andi Haris ◽  
Kian Meng Lim ◽  
Jinlong Xie ◽  
Heow Pueh Lee
Keyword(s):  
White Noise ◽  
Traffic Noise ◽  
Noise Pollution ◽  
Experimental Results ◽  
Frequency Range ◽  
Noise Mitigation ◽  
Noise Sources ◽  
Acoustic Performance ◽  
Common Noise ◽  
The Common

In the present study, a conventional plenum window was incorporated with perforated thin box in order to enhance its performance at frequency range which centralized at 1000 Hz as most of the common noise sources at city nowadays are centralizing around this frequency. The entire studies were conducted in a reverberation room. The effectiveness of jagged flap on mitigating diffracted sound was also studied. Three types of noises were examined in the current study—white noise, traffic noise and construction noises. The experimental results showed that the plenum window with perforated thin box could reduce 8.4 dBA, 8.7 dBA and 6.9 dBA of white, traffic and construction noises, respectively. The jagged flaps did not have significant effect on the plenum window’s noise mitigation performance. When frequencies were ranging from 800 Hz to 1250 Hz, when compared with the case of without perforated thin box, it was found that the perforated thin box had good acoustic performance where it was able to reduce additional 1.6 dBA, 1.6 dBA and 1.2 dBA of white, construction and traffic noises, respectively.

Design and modeling of an ultra-wideband low-noise distributed amplifier in InP DHBT technology

2019 ◽  
Vol 11 (7) ◽  
pp. 635-644 ◽  
Author(s):  
T. Shivan ◽  
E. Kaule ◽  
M. Hossain ◽  
R. Doerner ◽  
T. Johansen ◽  
...  
Keyword(s):  
Noise Figure ◽  
Impedance Matching ◽  
Low Noise ◽  
Ultra Wideband ◽  
Frequency Range ◽  
Collector Current ◽  
Noise Sources ◽  
Distributed Amplifier ◽  
Double Heterojunction ◽  
High Bandwidth

AbstractThis paper reports on an ultra-wideband low-noise distributed amplifier (LNDA) in a transferred-substrate InP double heterojunction bipolar transistor (DHBT) technology which exhibits a uniform low-noise characteristic over a large frequency range. To obtain very high bandwidth, a distributed architecture has been chosen with cascode unit gain cells. Each unit cell consists of two cascode-connected transistors with 500 nm emitter length and ft/fmax of ~360/492 GHz, respectively. Due to optimum line-impedance matching, low common-base transistor capacitance, and low collector-current operation, the circuit exhibits a low-noise figure (NF) over a broad frequency range. A 3-dB bandwidth from 40 to 185 GHz is measured, with an NF of 8 dB within the frequency range between 75 and 105 GHz. Moreover, this circuit demonstrates the widest 3-dB bandwidth operation among all reported single-stage amplifiers with a cascode configuration. Additionally, this work has proposed that the noise sources of the InP DHBTs are largely uncorrelated. As a result, a reliable prediction can be done for the NF of ultra-wideband circuits beyond the frequency range of the measurement equipment.

Sign in / Sign up

Export Citation Format

Share Document