The impact of bubble curtains on seismic air-gun signatures and its high-frequency emission

Geophysics ◽  
2020 ◽  
Vol 85 (2) ◽  
pp. P1-P11
Author(s):  
Daniel Wehner ◽  
Martin Landrø
Keyword(s):  
High Frequency ◽  
Air Injection ◽  
Offshore Wind ◽  
Peak Amplitude ◽  
Common Source ◽  
High Frequencies ◽  
Air Gun ◽  
Source Signal ◽  
The Impact ◽  
Bubble Curtain

In marine seismic acquisition, air guns are the most common source and, in recent years, research on their impact on the marine environment has increased. The main focus is on the reduction of emitted high frequencies, approximately greater than 200 Hz, which are normally not useful for seismic imaging. Therefore, potential ways to reduce the high frequencies from air guns are investigated and the development of alternative source types has increased. We have investigated the impact of bubble curtains on the source signature from seismic air guns because bubble curtains are known to mitigate high frequencies in other applications, e.g., pile driving for offshore wind farms. We have conducted tank experiments with two different configurations of bubble curtains around a single air gun and compared the results to the conventional source signature without a bubble curtain. The two different bubble curtains vary in size and in the way they are attached to the air gun. The amount of injected air into the bubble curtains is varied for both configurations. We compare the measured results to simulated data using a common model for air-gun source signatures. The results indicate a reduced peak amplitude with increasing air injection through the bubble curtain. This corresponds to a gradually decreasing frequency content for frequencies greater than 50 Hz. The frequencies of the source signal of less than 50 Hz are practically unaffected by the bubble curtain. In addition, the bubble time period of the source signal is slightly increased with an increasing amount of air injection through the bubble curtain. The main cause for the reduced peak amplitude is likely to be a buffer effect of the bubble curtain on the released air. Hence, a bubble curtain concentrated around the air-gun ports could be an efficient and practical solution to reduce the high-frequency acoustic emission from air guns.

scholarly journals Investigation of Tinnitus Patients in Italy: Clinical and Audiological Characteristics

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Francesco Martines ◽  
Daniela Bentivegna ◽  
Fabiola Di Piazza ◽  
Enrico Martines ◽  
Vincenzo Sciacca ◽  
...  
Keyword(s):  
Hearing Loss ◽  
High Frequency ◽  
Pure Tone ◽  
Hearing Threshold ◽  
Related Factors ◽  
High Frequencies ◽  
Tinnitus Severity ◽  
Hearing Status ◽  
Neural Connection ◽  
The Impact

Objective. 312 tinnitus sufferers were studied in order to analyze: the clinical characteristics of tinnitus; the presence of tinnitus-age correlation and tinnitus-hearing loss correlation; the impact of tinnitus on subjects' life and where possible the etiological/predisposing factors of tinnitus.Results. There is a slight predominance of males. The highest percentage of tinnitus results in the decades 61–70. Of the tinnitus sufferers, 197 (63.14%) have a hearing deficit (light hearing loss in 37.18% of cases). The hearing impairment results of sensorineural type in 74.62% and limited to the high frequencies in 58.50%. The tinnitus is referred as unilateral in 59.93%, a pure tone in 66.99% and 10 dB above the hearing threshold in 37.7%. It is limited to high frequencies in 72.10% of the patients with sensorineural hearing loss (SNHL) while the 88.37% of the patients with high-frequency SNHL have a high-pitched tinnitus ( ).Conclusion. Hearing status and age represent the principal tinnitus related factors; there is a statistically significant association between high-pitched tinnitus and high-frequency SNHL. There is no significant correlation between tinnitus severity and tinnitus loudness confirming the possibility that neural connection involved in evoking tinnitus-related negative reactions are governed by conditioned reflexes.

Repeatability issues of high-frequency signals emitted by air-gun arrays

Geophysics ◽  
2013 ◽  
Vol 78 (6) ◽  
pp. P19-P27 ◽  
Author(s):  
Martin Landrø ◽  
Lasse Amundsen ◽  
Jan Langhammer
Keyword(s):  
High Frequency ◽  
Field Measurements ◽  
Typical Feature ◽  
Main Peak ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Surface Reflection ◽  
Air Gun ◽  
Source Signal ◽  
Marine Seismic

Recent field measurements of the acoustic signals generated by marine seismic air-gun arrays showed that the amount of high-frequency signals (above 10 kHz) increased with the size and total volume of the gun array. We found that for frequencies between 10 and 20 kHz, a strong signal is observed 7–14 ms after the main peak of the source signal. We believe that this signal was generated by ghost cavitation. We observed that this signal was significantly stronger than the high-frequency signal generated at the same time as the peak signal occurs within the bandwidth between 10 and 20 kHz. We found that this high-frequency signal was fairly repeatable from one shot to another. By “fairly,” we mean that individual high-frequency events were not repeatable; however, the envelope energy of this cascade of events was repeatable from one shot to another. The typical feature of the envelope of the high-frequency signal was that it lasted for approximately 6–7 ms and showed a monotonic increase in amplitude for the first 5–6 ms, followed by a sudden drop. The sea surface reflection coefficient for these high-frequency events seemed to decrease in magnitude as the frequency increased.

The Impact of Noise Expose on the Hearing Threshold Extended High Frequency

2008 ◽  
Vol 20 (2) ◽  
pp. 81 ◽  
Author(s):  
Nam Jeong Kim ◽  
Joong Keun Kwon ◽  
Ji Ho Lee
Keyword(s):  
High Frequency ◽  
Hearing Threshold ◽  
The Impact

Global Algorithmic Capital Markets

2018 ◽  
Keyword(s):  
Public Policy ◽  
Capital Markets ◽  
Systemic Risk ◽  
High Frequency ◽  
Investor Protection ◽  
High Frequency Trading ◽  
Market Making ◽  
Market Governance ◽  
Policy Objectives ◽  
The Impact

This book illustrates and assesses the dramatic recent transformations in capital markets worldwide and the impact of those transformations. ‘Market making’ by humans in centralized markets has been replaced by supercomputers and algorithmic high frequency trading operating in often highly fragmented markets. How do recent market changes impact on core public policy objectives such as investor protection, reduction of systemic risk, fairness, efficiency, and transparency in markets? The operation and health of capital markets affect all of us and have profound implications for equality and justice in society. This unique set of chapters by leading scholars, industry insiders, and regulators sheds light on these and related questions and discusses ways to strengthen market governance for the benefit of society at large.

scholarly journals Impact of the Wind Turbine on the Parameters of the Electricity Supply to an Agricultural Farm

2021 ◽  
Vol 13 (13) ◽  
pp. 7279
Author(s):  
Zbigniew Skibko ◽  
Magdalena Tymińska ◽  
Wacław Romaniuk ◽  
Andrzej Borusiewicz
Keyword(s):  
Power Plant ◽  
Wind Turbine ◽  
Wind Power ◽  
Rural Areas ◽  
Power Plants ◽  
Reactive Power ◽  
Supply Voltage ◽  
Common Source ◽  
Voltage Fluctuations ◽  
The Impact

Wind power plants are an increasingly common source of electricity located in rural areas. As a result of the high variability of wind power, and thus the generated power, these sources should be classified as unstable sources. In this paper, the authors attempted to determine the impact of wind turbine operation on the parameters of electricity supplied to farms located near the source. As a result of the conducted field tests, variability courses of the basic parameters describing the supply voltage were obtained. The influence of power plant variability on the values of voltage, frequency, and voltage distortion factor was determined. To estimate the capacity of the transmission lines, the reactive power produced in the power plant and its effect on the value of the power factor were determined. The conducted research and analysis showed that the wind power plant significantly influences voltage fluctuations in its immediate vicinity (the maximum value registered was close to 2%, while the value required by law was 2.5%). Although all the recorded values are within limits specified by the current regulations (e.g., the THD value is four times lower than the required value), wind turbines may cause incorrect operation of loads connected nearby. This applies mainly to cases where consumers sensitive to voltage fluctuations are installed in the direct vicinity of the power plant.

scholarly journals Crisis Management in Higher Education in the Time of Covid-19: The Case of Actor Training

2021 ◽  
Vol 11 (3) ◽  
pp. 132
Author(s):  
Anna McNamara
Keyword(s):  
Higher Education ◽  
Crisis Management ◽  
High Frequency ◽  
High Reliability ◽  
Actor Training ◽  
Management Actions ◽  
The Usa ◽  
The Uk ◽  
The Impact ◽  
High Frequency Words

The impact of Covid-19 placed Higher Education leadership in a state of crisis management, where decision making had to be swift and impactful. This research draws on ethea of mindfulness, actor training techniques, referencing high-reliability organisations (HRO). Interviews conducted by the author with three leaders of actor training conservatoires in Higher Education institutions in Australia, the UK and the USA reflect on crisis management actions taken in response to the impact of Covid-19 on their sector, from which high-frequency words are identified and grouped thematically. Reflecting on these high-frequency words and the thematic grouping, a model of mindful leadership is proposed as a positive tool that may enable those in leadership to recognise and respond efficiently to wider structural frailties within Higher Education, with reference to the capacity of leaders to operate with increased mindfulness, enabling a more resilient organisation that unlocks the locus of control.

scholarly journals Rheology of rounded mammalian cells over continuous high-frequencies

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gotthold Fläschner ◽  
Cosmin I. Roman ◽  
Nico Strohmeyer ◽  
David Martinez-Martin ◽  
Daniel J. Müller
Keyword(s):  
High Frequency ◽  
Mammalian Cells ◽  
Mechanical Response ◽  
Cell Mass ◽  
Low Frequency ◽  
Mass Measurements ◽  
High Frequencies ◽  
Polymer Relaxation ◽  
Continuous Frequency ◽  
Rheological Experiments

AbstractUnderstanding the viscoelastic properties of living cells and their relation to cell state and morphology remains challenging. Low-frequency mechanical perturbations have contributed considerably to the understanding, yet higher frequencies promise to elucidate the link between cellular and molecular properties, such as polymer relaxation and monomer reaction kinetics. Here, we introduce an assay, that uses an actuated microcantilever to confine a single, rounded cell on a second microcantilever, which measures the cell mechanical response across a continuous frequency range ≈ 1–40 kHz. Cell mass measurements and optical microscopy are co-implemented. The fast, high-frequency measurements are applied to rheologically monitor cellular stiffening. We find that the rheology of rounded HeLa cells obeys a cytoskeleton-dependent power-law, similar to spread cells. Cell size and viscoelasticity are uncorrelated, which contrasts an assumption based on the Laplace law. Together with the presented theory of mechanical de-embedding, our assay is generally applicable to other rheological experiments.

scholarly journals Evaluation of offshore wind power in the China sea

2021 ◽  
pp. 014459872199226
Author(s):  
Yu-chi Tian ◽  
Lei kou ◽  
Yun-dong Han ◽  
Xiaodong Yang ◽  
Ting-ting Hou ◽  
...  
Keyword(s):  
Wind Energy ◽  
Wind Power ◽  
Energy Development ◽  
Offshore Wind ◽  
Human Beings ◽  
Offshore Wind Power ◽  
Business Operation ◽  
Advantages And Disadvantages ◽  
Wind Energy Development ◽  
The Impact

With resource crisis and environmental crisis increasingly grim, many countries turn the focus to pollution-free and renewable wind energy resources, which are mainly used for offshore wind power generation, seawater desalination and heating, etc., on the premise that the characteristics of resources are fully grasped. In this study, the evaluation of offshore wind energy in offshore waters in China, as well as the advantages and disadvantages of existing studies were overviewed from four aspects: the spatial-temporal characteristics of wind energy, wind energy classification, the short-term forecast of wind energy and the long-term projection of wind energy, according to the research content and the future considerations about wind energy evaluation (evaluation of wind energy on islands and reefs, the impact of wind energy development on human health) were envisaged, in the hope of providing a scientific basis for the site selection and business operation ‘or military applications’ here (after business operation), etc. of wind energy development, ‘aritime navigation against environmental construction,’ here and also contributing to the sustainable development and health of human beings.

scholarly journals Sensitivity of Ultrasonic Coda Wave Interferometry to Material Damage—Observations from a Virtual Concrete Lab

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4033
Author(s):  
Claudia Finger ◽  
Leslie Saydak ◽  
Giao Vu ◽  
Jithender J. Timothy ◽  
Günther Meschke ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Concrete Specimen ◽  
Coda Wave ◽  
Velocity Change ◽  
Damage Scenarios ◽  
Different Types ◽  
Source Signal ◽  
The Impact ◽  
Structural Scale ◽  
Coda Wave Interferometry

Ultrasonic measurements are used in civil engineering for structural health monitoring of concrete infrastructures. The late portion of the ultrasonic wavefield, the coda, is sensitive to small changes in the elastic moduli of the material. Coda Wave Interferometry (CWI) correlates these small changes in the coda with the wavefield recorded in intact, or unperturbed, concrete specimen to reveal the amount of velocity change that occurred. CWI has the potential to detect localized damages and global velocity reductions alike. In this study, the sensitivity of CWI to different types of concrete mesostructures and their damage levels is investigated numerically. Realistic numerical concrete models of concrete specimen are generated, and damage evolution is simulated using the discrete element method. In the virtual concrete lab, the simulated ultrasonic wavefield is propagated from one transducer using a realistic source signal and recorded at a second transducer. Different damage scenarios reveal a different slope in the decorrelation of waveforms with the observed reduction in velocities in the material. Finally, the impact and possible generalizations of the findings are discussed, and recommendations are given for a potential application of CWI in concrete at structural scale.

scholarly journals Exploring the impact of innovative developments to the installation process for an offshore wind farm

2015 ◽  
Vol 109 ◽  
pp. 623-634 ◽  
Author(s):  
Euan Barlow ◽  
Diclehan Tezcaner Öztürk ◽  
Matthew Revie ◽  
Evangelos Boulougouris ◽  
Alexander H. Day ◽  
...  
Keyword(s):  
Wind Farm ◽  
Offshore Wind ◽  
Offshore Wind Farm ◽  
The Impact
Sign in / Sign up

Export Citation Format

Share Document