Methods to ascertain the resistance of stranded conductors in the frequency range of 40 Hz–150 kHz

2019 ◽  
Vol 174 ◽  
pp. 105862 ◽  
Author(s):  
András Mohos ◽  
József Ladányi ◽  
Dániel Divényi
Keyword(s):  
Frequency Range ◽  
40 Hz

scholarly journals The effect of 2020 COVID-19 lockdown measures on seismic noise recorded in Romania

Solid Earth ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 2351-2368
Author(s):  
Bogdan Grecu ◽  
Felix Borleanu ◽  
Alexandru Tiganescu ◽  
Natalia Poiata ◽  
Raluca Dinescu ◽  
...  
Keyword(s):  
Noise Reduction ◽  
High Frequency ◽  
Urban Areas ◽  
Seismic Noise ◽  
Human Mobility ◽  
Vertical Component ◽  
World Health ◽  
High Frequency Range ◽  
Frequency Range ◽  
40 Hz

Abstract. After the World Health Organization declared COVID-19 a pandemic in March 2020, Romania followed the example of many other countries and imposed a series of restrictive measures, including restricting people's mobility and closing social, cultural, and industrial activities to prevent the spread of the disease. In this study, we analyze continuous vertical component recordings from the stations of the Romanian Seismic Network – one of the largest networks in Europe, consisting of 148 stations – to explore the seismic noise variation associated with the reduced human mobility and activity due to the Romanian measures against COVID-19 in detail. We focused our investigation on four frequency bands – 2–8, 4–14, 15–25 and 25–40 Hz – and found that the largest reductions in seismic noise associated with the lockdown correspond to the high-frequency range of 15–40 Hz. We found that all the stations with large reductions in seismic noise (>∼  40 %) are located inside and near schools or in buildings, indicating that at these frequencies the drop is related to the drastic reduction of human activity in these edifices. In the lower-frequency range (2–8 and 4–14 Hz) the variability of the noise reduction among the stations is lower than in the high-frequency range, corresponding to about 35 % on average. This drop is due to reduced traffic during the lockdown, as most of the stations showing such changes in seismic noise in these bands are located within cities and near main or side streets. In addition to the noise reduction observed at stations located in populated areas, we also found seismic noise lockdown-related changes at several stations located far from urban areas, with movement of people in the vicinity of the station explaining the noise reductions.

scholarly journals The effect of 2020 COVID-19 lockdown measures on seismic noise recorded in Romania

2021 ◽  
Author(s):  
Bogdan Grecu ◽  
Felix Borleanu ◽  
Alexandru Tiganescu ◽  
Natalia Poiata ◽  
Raluca Dinescu ◽  
...  
Keyword(s):  
Noise Reduction ◽  
High Frequency ◽  
Seismic Noise ◽  
Human Mobility ◽  
Vertical Component ◽  
World Health ◽  
High Frequency Range ◽  
Frequency Range ◽  
Noise Characteristics ◽  
40 Hz

Abstract. After the World Health Organization declared COVID-19 a pandemic in March 2019, Romania followed the example of many other countries and imposed a series of restrictive measures, including restricting people's mobility and closing social, cultural and industrial activities to prevent the spread of the disease. In this study, we analyze continuous vertical component recordings from the stations of the Romanian Seismic Network – one of the largest networks in Europe containing 148 stations – to explore in detail the seismic noise variation associated with the reduced human mobility and activity in Romania due to COVID-19. We focused our investigation on four frequency bands – 2–8 Hz, 4–14 Hz, 15–25 Hz and 25–40 Hz – and found that the largest reductions in seismic noise associated with the lockdown corresponds to the high frequency range, from 15 to 40 Hz. We found that all the stations with large reductions in seismic noise (> ~40 %) are located inside and near schools or in buildings, indicating that at these frequencies the drop is related to the drastic reduction of human activity in these edificies. In the lower frequency range (2–8 Hz and 4–14 Hz) the variability of the noise reduction among the stations is lower than in the high frequency range, and the noise level is reduced by up to 35 %. This drop is due to reduced traffic during the lockdown, as most of the stations showing such changes in seismic noise in these bands are located within cities, near main or side streets. In addition to the noise reduction observed at stations located in populated areas, we also found seismic noise lockdown-related changes at several stations located far from urban areas, with movement of people in the vicinity of the station explaining the noise reductions. Apart from the opportunity to investigate in more detail the seismic noise characteristics due to human mobility and activity, we show that noise reduction during the lockdown has also improved the earthquake detection capability of the accelerometers located in noisy urban environments.

scholarly journals Dielectric relaxation of nonaqueous ionic liquid microemulsions: polarization, microstructure, and phase transition

RSC Advances ◽  
2017 ◽  
Vol 7 (23) ◽  
pp. 13733-13741 ◽  
Author(s):  
Cancan Zhang ◽  
Zhen Zhen ◽  
Liyan Ma ◽  
Kongshuang Zhao
Keyword(s):  
Phase Transition ◽  
Ionic Liquid ◽  
Dielectric Relaxation ◽  
Dielectric Spectroscopy ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
40 Hz

Two nonaqueous ionic liquid (IL) microemulsions (toluene/TX-100/[bmim][PF6] and [bmim][BF4]/TX-100/benzene) were studied by dielectric spectroscopy covering a wide frequency range (40 Hz to 110 MHz).

scholarly journals Geophysical Observatory in Kamchatka region for monitoring of phenomena connected with seismic activity

2001 ◽  
Vol 1 (1/2) ◽  
pp. 3-7 ◽  
Author(s):  
S. Uyeda ◽  
T. Nagao ◽  
K. Hattori ◽  
M. Hayakawa ◽  
K. Miyaki ◽  
...  
Keyword(s):  
Electric Potential ◽  
Seismic Activity ◽  
Research Projects ◽  
Frequency Range ◽  
Regular Monitoring ◽  
Geophysical Observatory ◽  
Kamchatka Region ◽  
40 Hz

Abstract. Regular monitoring of some geophysical parameters in association with seismicity has been carried out since last year at the Japan-Russian Complex Geophysical Observatory in the Kamchatka region. This observatory was organized in connection with the ISTC project in Russia and was motivated by the results of the FRONTIER/RIKEN and FRONTIER/NASDA research projects in Japan. The main purpose of the observations is to investigate the electromagnetic and acoustic phenomena induced by the lithosphere processes (especially by seismic activity). The seismicity of the Kamchatka area is analyzed and a description of the observatory equipment is presented. At present, the activity of the observatory includes the seismic (frequency range ∆F = 0.5 – 40 Hz) and meteorological recordings, together with seismo-acoustic (∆F = 30 – 1000 Hz) and electromagnetic observations: three-component magnetic ULF variations ( ∆F = 0.003 – 30 Hz), three-component electric potential variations ( ∆F < 1.0 Hz), and VLF transmitter’s signal perturbations ( ∆F ~ 10 – 40 kHz).

scholarly journals Features of time variations of microseismic noise at seismic stations in Tajikistan

2021 ◽  
Vol 3 (4) ◽  
pp. 18-37
Author(s):  
Vladimir Zhuravlev ◽  
Albert Lukk
Keyword(s):  
High Frequency ◽  
Noise Level ◽  
Low Frequency ◽  
Frequency Noise ◽  
Noise Amplitude ◽  
Low Frequency Noise ◽  
Frequency Range ◽  
Seismic Stations ◽  
High Frequency Noise ◽  
40 Hz

The spectral structure of microseismic noise in the frequency range of 0.01-40 Hz at different times of the day and year, recorded by broadband equipment at eight IRIS group seismic stations in Tajikistan in 2005-2020, was analyzed. Two disjoint frequency ranges are distinguished, which we conditionally call "high-frequency" (2-40 Hz) and "low-frequency" (0.01-0.75 Hz) noise, separated by a natural drop in the noise amplitude to 20-30 Db. It is assumed that the high-frequency range of noise has a local nature, due to exogenous sources of natural origin in the form of wind gusts, concussions from powerful watercourses and fluctuations in the level of large reservoirs, as well as man-made in-terference due to road and quarry explosions, the work of large industrial enterprises and concussions from road traffic. Low-frequency noise is most likely caused by global storm microseisms. High-frequency noise has a well-defined daily frequency, which is completely absent in low-frequency noise. At the same time, in both frequency ranges, the existence of a clearly pronounced seasonal peri-odicity has been established, the amplitude of which reaches 6-7 Db for high-frequency noise and about half as much for low-frequency noise. However, at the same time, the seasonal frequency of high frequency and low-frequency noise turns out to be antiphase, which indicates in favor of the different genesis of these two components of microseismic noise. The amplitude of the diurnal periodicity in variations of the high-frequency noise level is maximal during the daytime, remaining approximately constant for 8-10 hours. At the same time, the decline in the noise amplitude in the evening lasts longer than the steeper morning growth. The time intervals of a sharp increase and decrease in the intensity of the discussed daily extreme are quite well correlated, respectively, with morning and evening twilight at different times of the year. This is reflected in the wider flat part of the maximum noise level in summer compared to winter and the differences in its level up to 6 Db in favor of summer time. This observation can be considered as a manifestation of the deep influence of the Sun on the oscillatory processes that generate high-frequency microseismic noise.

Transmission of Vibration to the Hand

1992 ◽  
Vol 11 (1) ◽  
pp. 14-22 ◽  
Author(s):  
A. Sörensson ◽  
R. Lundström
Keyword(s):  
Grip Force ◽  
Middle Finger ◽  
Excitation Level ◽  
Frequency Range ◽  
Laser Technique ◽  
Vibration Transmission ◽  
Contact Measurement ◽  
Complicated Pattern ◽  
Test Points ◽  
40 Hz

The transmission of vibration from a handle to twelve test points located on the volar side of the hands of five females and five males was determined with laser technique for non-contact measurement of vibration. The excitation level was almost constant (0.01 m/srms) within the frequency range of 12.5 to 1250 Hz. The grip force exerted by the subjects was 10 N. Vibration at frequencies below 40 Hz was in general transmitted to all test points without any noticeable attenuation.-Far higher frequencies and for test points adjacent to the wrist the transmission of vibration decreased with the frequency (5 dB/octave). For test points on the nails of the middle finger and thumb the un-attenuated frequency range was extended up to about 500 Hz. For other test points a more complicated pattern was observed and in the frequency range of 40–160 Hz, vibration was seen to be either fully transmitted or even amplified Only small and unclear differences in vibration transmission between females and males were observed.

An Investigation of the Perception Thresholds of Band-Limited Low Frequency Noises: Influence of Bandwidth

2003 ◽  
Vol 22 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Yasunao Matsumoto ◽  
Yukio Takahashi ◽  
Setsuo Maeda ◽  
Hiroki Yamaguchi ◽  
Kazuhiro Yamada ◽  
...  
Keyword(s):  
Sound Pressure ◽  
Low Frequency ◽  
Frequency Range ◽  
Pass Filter ◽  
Sound Pressure Levels ◽  
Pure Tones ◽  
Band Limited ◽  
The One ◽  
Frequency Weighting ◽  
40 Hz

Perception thresholds of complex low frequency noises have been investigated in a laboratory experiment. Sound pressure levels that were just perceptible by subjects were measured for three complex noises and three pure tones. The complex noises had a flat constant spectrum over the frequency range 2 to 10, 20, or 40 Hz and decreased at 15 dB per octave at higher frequencies. The frequencies of the pure tones used in this study were 10, 20 and 40 Hz. The perception thresholds were obtained using an all-pass filter, one-third octave band filters, and the G frequency weighting defined in ISO 7196. The G-weighted sound pressure levels obtained were compared with 100 dB which is described in ISO 7196 as the G-weighted level corresponding to the threshold of sounds in the frequency range 1 to 20 Hz. The perception thresholds of the pure tones measured in this study were comparable to the results available in various previous studies. The one-third octave sound pressure levels obtained for the thresholds of the complex noises appeared to be lower than the measured thresholds of the pure tones. The G-weighted sound pressure levels obtained for the thresholds of the complex noises appeared to be lower than 100 dB.

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