The variability of naturally occurring magnetic field levels: 10 Hz to 8 kHz

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. F187-F197 ◽  
Author(s):  
Ben K. Sternberg
Keyword(s):  
Magnetic Field ◽  
Noise Level ◽  
Monsoon Season ◽  
Signal Frequency ◽  
Time Interval ◽  
Frequency Range ◽  
Noise Levels ◽  
Controlled Source ◽  
Naturally Occurring ◽  
Minimum Noise

The variability of naturally occurring magnetic fields in the frequency range from [Formula: see text] over a period of one year was studied. Contour plots for the [Formula: see text], [Formula: see text], and [Formula: see text] components and for frequencies of 10, 100, 1000, 2000, and 8000 Hz were produced. Average, minimum, maximum, and the standard deviations of these fields were also calculated for 12 distinctive time intervals. In the 1– to 8–kHz frequency range, the noise levels are typically higher at night. In the 10- to 100-Hz frequency range, the noise levels are typically higher during the day. During mid- to late-summer, there is frequent thunderstorm activity, known in the southwest United States as the monsoon season. The magnetic field levels are often very high during this time period. These variability ranges can be used to estimate the lowest levels of noise that may be encountered during field surveys, which iswhat the authors are looking for when running controlled-source electrical method surveys. These variability ranges can also be used to estimate the highest levels that may be encountered, which is what the authors are looking for when running natural-source electrical methods surveys, such as audio frequency magnetotelluric (AMT) surveys. These measurements of magnetic field strength variability show that better data for controlled-source electrical measurements can be obtained using the minimum noise level measurements, as opposed to using signal integration or signal averaging with all of the data. The minimum noise level is found by using frequency bins adjacent to the signal-frequency bin. Likewise, if one is interested in measuring the naturally occurring magnetic field data, using the maximum values during each time interval makes AMT measurements possible when the natural signal level is very low, particularly in the AMT dead zone around [Formula: see text].

scholarly journals Assessment of noise pollution in Haridwar city of Uttarakhand State, India during Kumbh Mela 2010 and its impact on human health

2010 ◽  
Vol 2 (2) ◽  
pp. 293-295
Author(s):  
S. Madan ◽  
Pallavi Pallavi
Keyword(s):  
Human Health ◽  
Noise Level ◽  
Ambient Noise ◽  
Noise Pollution ◽  
Noise Levels ◽  
High Noise ◽  
Minimum Noise

The present study was carried to investigate the noise level at four different locations of Haridwar viz. Singh Dwar, Rishikul, Chandi ghat and Har Ki Pauri during Kumbh Mela 2010. During normal days maximum noise levels were recorded at Chandi ghat i.e. 87.11±0.45 dB (A) in the evening hours and minimum noise levels were recorded at Har Ki Pauri i.e. 60.8±0.89 dB (A) in the morning hours. While during festival days maximum noise levels were at Har Ki Pauri i.e. 88.4 ± 1.65 dB (A) in the evening respectively and Rishikul the least being 54.93±0.53 dB (A) in the morning hours. Noise levels in all the areas were found to be above the ambient noise standard. These high noise levels may have induced headache, annoyance, lack of concentration and other varied effects on human health.

scholarly journals The Effect of the Ionosphere on the Controlled-Source Field in the Frequency Range between 0.4 and 95 Hz

2021 ◽  
Author(s):  
Pavel Tereshchenko
Keyword(s):  
Magnetic Field ◽  
Kola Peninsula ◽  
Geomagnetic Activity ◽  
The State ◽  
Topside Ionosphere ◽  
Frequency Range ◽  
Controlled Source ◽  
The Earth ◽  
Source Field ◽  
The Magnetic Field

The paper addresses the effect of the ionosphere on the ELF and lower frequency waves excited in the Earth-ionosphere waveguide by a controlled source. The experiment carried out on the Kola Peninsula is described and the results of measurements in the frequency range 0.4–95 Hz are presented. Non-monotonic behavior of the magnetic field with time is revealed. It is shown that variations in the magnetic field are related to the state of the ionosphere and depend on the geomagnetic activity. The importance of the effect of the topside ionosphere on the structure of the studied field is discussed.

scholarly journals The Effect of the Ionosphere on the Controlled-Source Field in the Frequency Range between 0.4 and 95 Hz

2021 ◽  
Author(s):  
Pavel Tereshchenko
Keyword(s):  
Magnetic Field ◽  
Kola Peninsula ◽  
Geomagnetic Activity ◽  
The State ◽  
Topside Ionosphere ◽  
Frequency Range ◽  
Controlled Source ◽  
The Earth ◽  
Source Field ◽  
The Magnetic Field

The paper addresses the effect of the ionosphere on the ELF and lower frequency waves excited in the Earth-ionosphere waveguide by a controlled source. The experiment carried out on the Kola Peninsula is described and the results of measurements in the frequency range 0.4–95 Hz are presented. Non-monotonic behavior of the magnetic field with time is revealed. It is shown that variations in the magnetic field are related to the state of the ionosphere and depend on the geomagnetic activity. The importance of the effect of the topside ionosphere on the structure of the studied field is discussed.

scholarly journals Noise in Otolaryngology – Head and Neck Surgery operating rooms: a systematic review

2021 ◽  
Vol 50 (1) ◽  
Author(s):  
Gianluca Sampieri ◽  
Amirpouyan Namavarian ◽  
Marc Levin ◽  
Justine Philteos ◽  
Jong Wook Lee ◽  
...  
Keyword(s):  
Systematic Review ◽  
Head And Neck ◽  
Patient Outcomes ◽  
Noise Level ◽  
Neck Surgery ◽  
Operating Rooms ◽  
Head And Neck Surgery ◽  
Noise Levels ◽  
Surgical Performance ◽  
The Mean

Abstract Objective Noise in operating rooms (OR) can have negative effects on both patients and surgical care workers. Noise can also impact surgical performance, team communication, and patient outcomes. Such implications of noise have been studied in orthopedics, neurosurgery, and urology. High noise levels have also been demonstrated in Otolaryngology-Head and Neck Surgery (OHNS) procedures. Despite this, no previous study has amalgamated the data on noise across all OHNS ORs to determine how much noise is present during OHNS surgeries. This study aims to review all the literature on noise associated with OHNS ORs and procedures. Methods Ovid Medline, EMBASE Classic, Pubmed, SCOPUS and Cochrane databases were searched following PRISMA guidelines. Data was collected on noise measurement location and surgery type. Descriptive results and statistical analysis were completed using Stata. Results This search identified 2914 articles. Final inclusion consisted of 22 studies. The majority of articles analyzed noise level exposures during mastoid surgery (18/22, 82%). The maximum noise level across all OHNS ORs and OHNS cadaver studies were 95.5 a-weighted decibels (dBA) and 106.6 c-weighted decibels (dBC), respectively (P = 0.2068). The mean noise level across all studies was significantly higher in OHNS cadaver labs (96.9 dBA) compared to OHNS ORs (70.1 dBA) (P = 0.0038). When analyzed together, the mean noise levels were 84.9 dBA. Conclusions This systematic review demonstrates that noise exposure in OHNS surgery exceeds safety thresholds. Further research is needed to understand how noise may affect team communication, surgical performance and patient outcomes in OHNS ORs. Graphical abstract

Effective splicing localization based on noise level inconsistencies

2021 ◽  
pp. 1-11
Author(s):  
P. N. R. L. Chandra Sekhar Author ◽  
T. N. Shankar Author
Keyword(s):  
Digital Technology ◽  
Social Networking Sites ◽  
Noise Level ◽  
Research Work ◽  
Multimedia Content ◽  
Noise Levels ◽  
Multimedia Forensics ◽  
The Past ◽  
Photo Editing ◽  
State Of Art

In the era of digital technology, it becomes easy to share photographs and videos using smartphones and social networking sites to their loved ones. On the other hand, many photo editing tools evolved to make it effortless to alter multimedia content. It makes people accustomed to modifying their photographs or videos either for fun or extracting attention from others. This altering brings a questionable validity and integrity to the kind of multimedia content shared over the internet when used as evidence in Journalism and Court of Law. In multimedia forensics, intense research work is underway over the past two decades to bring trustworthiness to the multimedia content. This paper proposes an efficient way of identifying the manipulated region based on Noise Level inconsistencies of spliced mage. The spliced image segmented into irregular objects and extracts the noise features in both pixel and residual domains. The manipulated region is then exposed based on the cosine similarity of noise levels among pairs of individual objects. The experimental results reveal the effectiveness of the proposed method over other state-of-art methods.

scholarly journals Characterization of Noise Level Inside a Vehicle under Different Conditions

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2471 ◽  
Author(s):  
Daniel Flor ◽  
Danilo Pena ◽  
Luan Pena ◽  
Vicente A. de Sousa ◽  
Allan Martins
Keyword(s):  
Regression Analysis ◽  
Noise Level ◽  
Acoustic Noise ◽  
Experimental Setup ◽  
Strongly Correlated ◽  
Noise Levels ◽  
Noise Sources ◽  
Statistical Tools ◽  
Window Position

Vehicular acoustic noise evaluations are a concern of researchers due to health and comfort effects on humans and are fundamental for anyone interested in mitigating audio noise. This paper focuses on the evaluation of the noise level inside a vehicle by using statistical tools. First, an experimental setup was developed with microphones and a microcomputer located strategically on the car’s panel, and measurements were carried out with different conditions such as car window position, rain, traffic, and car speed. Regression analysis was performed to evaluate the similarity of the noise level from those conditions. Thus, we were able to discuss the relevance of the variables that contribute to the noise level inside a car. Finally, our results revealed that the car speed is strongly correlated to interior noise levels, suggesting the most relevant noise sources are in the vehicle itself.

Dual-finite distributed H∞ filtering in sensor networks

2021 ◽  
pp. 095965182199758
Author(s):  
Changshuo Wang ◽  
Jiwei Wen ◽  
Xiaoli Luan
Keyword(s):  
Sensor Networks ◽  
Disturbance Attenuation ◽  
Time Interval ◽  
Frequency Range ◽  
Frequency Scale ◽  
Attenuation Level ◽  
Exogenous Noise ◽  
Disturbance Attenuation Level ◽  
Reference Input ◽  
Filtering Approach

Generally, distributed H∞ filtering approach achieves a certain disturbance attenuation level in the full frequency range. However, the energy of system noise or reference input usually limits in a specified frequency range. To reduce such a design conservatism, this article develops a distributed filtering approach based on dual scale, that is, filtering over a finite-time interval from time scale and also on a specified finite-frequency region from the frequency scale. Our target is to make the filtering error under sensor networks monitoring be relaxed into an ellipsoid bound rather than asymptotically converging to zero for exogenous noise in a specified frequency range. Finally, two illustrative examples demonstrate the strength of the developed filtering approach.

Design of Control System for Hydraulically Vibrated Processing Tomato Fruit Seedling Separation Device

2014 ◽  
Vol 651-653 ◽  
pp. 693-696
Author(s):  
Li Hong Wang ◽  
Rong Qing Liang ◽  
Cheng Song Li ◽  
Za Kan ◽  
Jin Wei Qin
Keyword(s):  
Tomato Fruit ◽  
Simulation Software ◽  
Signal Frequency ◽  
System Control ◽  
Frequency Range ◽  
Hydraulic Simulation ◽  
Separation Device ◽  
Processing Tomato ◽  
Input Signal Frequency ◽  
Set Up

Eccentric style processing tomato fruit seeding separation device exist high machining and assembly precision or other issues. In order to solve this problem, the mode of vibration of hydraulic replaced the eccentric style to drive the fruit seedling separation roller to separate processing tomato effectively. To facilitate adjustment of the hydraulic system, a kind of control circuit PLC as the core was designed according to the actual production requirements. PLC and other elements were selected. The system control signal frequency was initially set up as 1~5 HZ, within the frequency range hydraulic simulation software was used to simulate and analyze the hydraulic vibration system. The result shows that the system rams steady when the input signal frequency range was 1~5HZ.

Noise Pollution in Onitsha Metropolis: Challenges and Solution

2021 ◽  
Vol 1 (2) ◽  
pp. 032-040
Author(s):  
Chris Onyeka Ekweozor ◽  
Johnbosco Emeka Umunnakwe ◽  
Leo O Osuji ◽  
Vincent C Weli
Keyword(s):  
State Government ◽  
Noise Level ◽  
Control Point ◽  
Noise Pollution ◽  
Health Impact ◽  
Dry Season ◽  
Noise Levels ◽  
Wet Season ◽  
High Noise ◽  
Anambra State

This study evaluated noise pollution in Onitsha metropolis, Anambra State, Nigeria in 2019. Noise levels were measured at forty sampling stations in the morning, afternoon and night within the study area for dry and wet seasons using modern noise level instruments. A control point was established at ldeani/Nnobi Junction with coordinates N 06o 05’.282’’ E 006o 55’.891’’ which was used as a reference point and for comparison with the sound levels recorded in designated locations. The results showed that the maximum noise level in the study area exceeded the Federal Ministry of Environment (FMEnv) limit by 7.8% in the dry season and by 13.11% in the wet season. Noise LAeq exceeded the NESREA LAeq limit by 29.89% in the dry season and by 33.44% in the wet season. The study indicated that the mean noise levels in the dry and wet seasons were within FMEnv limit of 90dB .It also showed that high noise levels were recorded around major junctions and market places within Onitsha, which are harmful to public health. The study further showed that transportation activities and trading activities at the market places are the main sources of high noise levels in the study area. Health impact assessment should be conducted in Onitsha metropolis for residents. State government should enforce compliance laws and regulate the activities of industries in the areas.

Absorption of hydromagnetic waves in the ionosphere

1970 ◽  
Vol 48 (3) ◽  
pp. 362-366
Author(s):  
M. Abbas
Keyword(s):  
Magnetic Field ◽  
Frequency Range ◽  
Parallel Propagation ◽  
Hydromagnetic Waves ◽  
The Magnetic Field

Absorption of hydromagnetic waves in the ionosphere propagated normal to the magnetic field is calculated at various frequencies and compared with the absorption for parallel propagation. Data corresponding to both daytime and nighttime ionospheres are used. Waves propagated normal to the magnetic field are highly absorbed through the daytime ionosphere at frequencies above a few Hz; the nighttime ionosphere, however, is virtually transparent to waves in the frequency range of 10−3 to 20 Hz. A comparison of the absorption processes for waves propagated parallel and normal to the magnetic field is made.

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