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1
Jia, Li Juan, Zhan Feng Qi, Sen Zhang, Yu Feng Qin, Jian Shi, Xuan Ming Zhang, and Xiu Jun Sun. "Dynamic Analysis of the Acoustic Velocity Profile Observation Underwater Glider." Applied Mechanics and Materials 475-476 (December 2013): 50–54. http://dx.doi.org/10.4028/www.scientific.net/amm.475-476.50.
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Underwater gliders carried acoustic velocity meters can realize ocean profile observations of the acoustic velocity for long duration and large scale. This paper mainly studies the kinematics and hydrodynamics of the Slocum underwater glider carrying a acoustic velocity meter MINOSX with length 565mm and diameter 76mm. Thus, theory reference for optimal design parameters of the underwater glider is proposed. By establishing the kinematic equations and giving some related parameters, variations with time of the steady-state gliding velocity, pitch angle, gliding path and attack angle are simulated by using Matlab software; The simulation calculations of the hydro-drag and lift are completed by using Fluent software. Finally, this paper summarizes the dynamic characteristics in steady state of the underwater glider in longitudinal plane.
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Betteridge, Kyle F. E., Peter D. Thorne, and Paul S. Bell. "Assessment of Acoustic Coherent Doppler and Cross-Correlation Techniques for Measuring Near-Bed Velocity and Suspended Sediment Profiles in the Marine Environment." Journal of Atmospheric and Oceanic Technology 19, no. 3 (March 1, 2002): 367–80. http://dx.doi.org/10.1175/1520-0426-19.3.367.
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Abstract The simultaneous measurement of current flow and suspended sediment concentration in the marine environment is central to the study of sediment transport processes. In view of this, two acoustic approaches for measuring flow were tested in a tidal estuary to assess their capabilities in this environment. A coherent Doppler velocity profiler and a cross-correlation velocity profiler were assessed using conventional current meters and a commercially available acoustic Doppler velocimeter. Mean velocity profiles were obtained up to a range of 1.47 m in 0.046-m range bins over a number of flood tides. The measurements compared well with the reference instruments and regression analysis produced gradients close to unity. Turbulent velocities measured with the coherent Doppler profiler were comparable with turbulent fluctuations measured with the acoustic Doppler velocimeter. The cross-correlation velocity profiler was shown to be unable to measure turbulent velocities. The backscattered signals received on the cross-correlation transducers were also used to compute the sediment concentration profiles using an explicit solution to the acoustic backscatter equation. Combining the concentration and flow measurements enabled sediment flux profiles to be obtained, the results of which compared favorably with flux measurements obtained from the conventional current meters and pumped sampling.
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Hogg, Nelson G., and Daniel E. Frye. "Performance of a New Generation of Acoustic Current Meters." Journal of Physical Oceanography 37, no. 2 (February 1, 2007): 148–61. http://dx.doi.org/10.1175/jpo3003.1.
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Abstract As part of a program aimed at developing a long-duration, subsurface mooring, known as Ultramoor, several modern acoustic current meters were tested. The instruments with which the authors have the most experience are the Aanderaa RCM11 and the Nortek Aquadopp, which measure currents using the Doppler shift of backscattered acoustic signals, and the Falmouth Scientific ACM, which measures changes in travel time of acoustic signals between pairs of transducers. Some results from the Doppler-based Sontek Argonaut and the travel-time-based Nobska MAVS are also reported. This paper concentrates on the fidelity of the speed measurement but also presents some results related to the accuracy of the direction measurement. Two procedures were used to compare the instruments. In one, different instruments were placed close to one another on three different deep-ocean moorings. These tests showed that the RCM11 measures consistently lower speeds than either a vector averaging current meter or a vector measuring current meter, both more traditional instruments with mechanical velocity sensors. The Aquadopp in use at the time, but since updated to address accuracy problems in low scattering environments, was biased high. A second means of testing involved comparing the appropriate velocity component of each instrument with the rate of change of pressure when they were lowered from a ship. Results from this procedure revealed no depth dependence or measurable bias in the RCM11 data, but did show biases in both the Aquadopp and Argonaut Doppler-based instruments that resulted from low signal-to-noise ratios in the clear, low scattering conditions beneath the thermocline. Improvements in the design of the latest Aquadopp have reduced this bias to a level that is not significant.
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Zhiyou, Liu, Huo Jinghuan, and Zhu Xiaogang. "The application of digital logging in exploration of Jiang Cang coalfield in Qinghai province." International Journal of Geology 1, no. 1 (July 21, 2016): 44. http://dx.doi.org/10.26789/ijg.2016.006.
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A lot of well logging on to Jiang Cang coalfield in the past work and achieved good results, but due to differ in age, instrumentation equipment and method were different. In order to understand the application effect of the equipment used in the area now and in order to provide the basis for the future working to choose the appropriate logging parameters and well logging interpretation, we chosed GJS - 1 b intelligent engineering logging system produced by Chongqing geological instrument factory in Jiang Cang mining area, we collected the data when cable were ascending, according to 《the requirements of the rules of coalfield geophysical logging》, JGS - 1 b instrument full hole resistivity logging velocity of 3 m/s, the sampling interval was 5 cm, acoustic logging measurement parameter for the acoustic time, adopt the device of single-emission and double-receiving, detectorsource space was 0.5 meters, 0.7 meters, the full hole velocity was 6 m/s, the sampling interval was 10 cm.In this paper, we introduce the application of multiple well logging method in coalfield geology through to the logging examples in Mu Li Jang Cang coalfield four field of qinghai province, the effect was remarkable
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Mayer, Dennis A., Jyotika I. Virmani, and Robert H. Weisberg. "Velocity Comparisons from Upward and Downward Acoustic Doppler Current Profilers on the West Florida Shelf." Journal of Atmospheric and Oceanic Technology 24, no. 11 (November 1, 2007): 1950–60. http://dx.doi.org/10.1175/jtech2094.1.
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Abstract Current observations are compared from upward- and downward-looking acoustic Doppler current profilers (ADCPs) deployed on the West Florida Shelf (WFS). Despite regional differences, statistical analyses show good agreement between all sets of observations throughout the water column except in the upper few meters where all downward-looking ADCPs exhibit small, but significant, reduction in rms speed values. Evidence suggests that this reduction is mooring related. It is possible that the presence of near-surface bubbles caused by wave activity could bias the near-surface observations. Otherwise, either the upward- or downward-looking mooring systems produce equivalent observations with differences due to spatial variations.
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Puzanau, A. D., and D. S. Nefedov. "Synthesis of algorithm of unmanned aerial vehicle detection by acoustic noise." Doklady BGUIR 19, no. 2 (March 27, 2021): 65–73. http://dx.doi.org/10.35596/1729-7648-2021-19-2-65-73.
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The algorithm of detection of acoustic noise provided by an unmanned aerial vehicle (UAV) in the noise background due to wind is synthesized in the article. Creation of the algorithm has been carried out using the Neyman – Pearson lemma. The algorithm assumes a combination of the stages of wind noise coherent compensation and coherent accumulation of UAV’s acoustic noise sound pressure impulses. The coherent accumulation time matches doubled time of fluctuation correlation resulted by experimental research of acoustic noise of different types of UAVs. Efficiency of the developed algorithm of UAV detection depends on flight velocity, foreshortening, amount of blades and rotor turnovers of UAV as well as weather conditions. For the probability of a false alarm value of 10–4, the probability of correct UAV detection value of 0.9 is provided wherein signal-to-noise ratio has a value of 8 dB. These indicators correspond the detection range of 200 to 300 meters. The obtained results allow discussions about perspective of acoustic UAVs detection systems adaptation.
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Bunge, Lucia, Christine Provost, Jonathan M. Lilly, Marc D’Orgeville, Annie Kartavtseff, and Jean-Luc Melice. "Variability of the Horizontal Velocity Structure in the Upper 1600 m of the Water Column on the Equator at 10°W." Journal of Physical Oceanography 36, no. 7 (July 1, 2006): 1287–304. http://dx.doi.org/10.1175/jpo2908.1.
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Abstract This paper presents initial results from new velocity observations in the eastern part of the equatorial Atlantic Ocean from a moored current-meter array. During the “EQUALANT” program (1999–2000), a mooring array was deployed around the equator near 10°W that recorded one year of measurements at various depths. Horizontal velocities were obtained in the upper 60 m from an upward-looking acoustic Doppler current profiler (ADCP) and at 13 deeper levels from current meters between 745 and 1525 m. To analyze the quasiperiodic variability observed in these records, a wavelet-based technique was used. Quasiperiodic oscillations having periods between 5 and 100 days were separated into four bands: 5–10, 10–20, 20–40, and 40–100 days. The variability shows (i) a strong seasonality (the first half of the series is dominated by larger periods than the second one) and (ii) a strong dependence with depth (some oscillations are present in the entire water column while others are only present at certain depths). For the oscillations that are present in the entire water column the origin of the forcing can be traced to the surface, while for the others the question of their origin remains open. Phase shifts at different depths generate vertical shears in the horizontal velocity component with relatively short vertical scales. This is especially visible in long-duration events (>100 days) of the zonal velocity component. Comparison with a simultaneous lowered acoustic Doppler current profiler (LADCP) section suggests that some of these flows may be identified with equatorial deep jets. A striking feature is a strong vertical shear lasting about 7 months between 745 and 1000 m. These deep current-meter observations would then imply a few months of duration for the jets in this region.
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Samuelsen, A., S. S. Hjøllo, J. A. Johannessen, and R. Patel. "Particle aggregation in anticyclonic eddies and implications for distribution of biomass." Ocean Science Discussions 9, no. 1 (January 18, 2012): 187–213. http://dx.doi.org/10.5194/osd-9-187-2012.
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Abstract. Acoustic measurements show that the biomass of zooplankton and mesopelagic fish is redistributed by mesoscale variability and that the signal extends over several hundred meters depth. The mechanisms governing this distribution are not well understood, but influences from both physical (i.e. physical redistribution) and biological processes (i.e. nutrient transport, primary production, active swimming, etc.) are likely. This study examines how hydrodynamic conditions and basic vertical swimming behavior act to distribute biomass in an anticyclonic eddy. Using an eddy-resolving 2.3 km-resolution physical ocean model as forcing for a particle-tracking module, particles representing passively floating organisms and organisms with vertical swimming behavior are released within an eddy and monitored for 20 to 30 days. The role of hydrodynamic conditions on the distribution of biomass is discussed in relation to the acoustic measurements. Particles released close to the surfaces tend, in agreement with the observations, to accumulate around the edge of the eddy, whereas particles released at depth tend to distribute along the isopycnals. After a month they are displaced several hundreds meters in the vertical with the deepest particles found close to the eddy center, but there is no evidence of aggregation of particles along the eddy rim. All in all, the particle redistribution appears to result from a complex mixture of strain and vertical velocity. The simplified view where the vertical velocity in eddies is regarded as uniform and symmetric around the eddy center is therefore not a reliable representation of the eddy dynamics.
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., Hartanto, Agust Tjahjono, and Rudy Sugiharto. "The characteristics of current patterns in the waters of port of Tanjung Emas Semarang." International Journal of Engineering & Technology 9, no. 2 (April 18, 2020): 403. http://dx.doi.org/10.14419/ijet.v9i2.30466.
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The Port of Tanjung Emas Semarang is located in the northern of Java which is regarded as a strategic position to support sea transportation connectivity to Kalimantan. Conducted at the Port of Tanjung Emas Semarang, this research applied exploratory descriptive as the research methodology. Measurements of this research were made by using ADCP (Acoustic Doppler Current meter Profiler) type of Multi Cell Argounaut-XR. The research was carried out in 3 days (January 16th, 2016 – January 19th, 2016). Current velocity data were taken at ± 7 meters depth in five depth strata. The research was aimed to measure the current pattern and distribution of ballast water discharges from commercial vessels at the port. Based on the research, it was found that the current velocity of all water columns in the port varied ranging from 0.042-0.124 m/s with minimum current velocity of 0.0–0.003 m/s and maximum current velocity of 0.139-0.452 m/s. It was also found that the dominant current direction was north and south. It was predicted that the distribution of the ballast water discharges during falling tide (the tide went from high to low) moved from south to north, heading the port exit. In contrast, during rising tide (the tide went from low to high), the distribution of the ballast water discharges moved from north to south, heading the estuary of Baru river.
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Morozov, E. G., R. Y. Tarakanov, and H. van Haren. "Transport of Antarctic bottom water through the Kane Gap, tropical NE Atlantic Ocean." Ocean Science 9, no. 5 (September 23, 2013): 825–35. http://dx.doi.org/10.5194/os-9-825-2013.
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Abstract. We study low-frequency properties of the Antarctic Bottom Water (AABW) flow through the Kane Gap (9° N) in the Atlantic Ocean. The measurements in the Kane Gap include five visits with CTD (Conductivity-Temperature-Depth) sections in 2009–2012 and a year-long record of currents on a mooring using three AquaDopp current meters. We found an alternating regime of flow, which changes direction several times during a year. The seasonal signal seems to dominate. The maximum daily average values of southerly velocities reach 0.20 m s−1, while the greatest north-northwesterly velocity is as high as 0.15 m s−1. The velocity and transport at the bottom are aligned along the slope of a local hill near the southwestern side of the gap. The distribution of velocity directions at the upper boundary of AABW is wider. The transport of AABW (Θ < 1.9 °C) based on the mooring and LADCP (Lowered Acoustic Doppler Current Profiler) data varies approximately within ±0.35 Sv in the northern and southern directions. The annual mean AABW transport through the Kane Gap is almost zero.
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Horstman, Erik, Thorsten Balke, Tjeerd Bouma, Marjolein Dohmen-Janssen, and Suzanne Hulscher. "OPTIMIZING METHODS TO MEASURE HYDRODYNAMICS IN COASTAL WETLANDS: EVALUATING THE USE AND POSITIONING OF ADV, ADCP AND HR-ADCP." Coastal Engineering Proceedings 1, no. 32 (January 31, 2011): 51. http://dx.doi.org/10.9753/icce.v32.waves.51.
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Hydrodynamic impacts of vegetation in the intertidal zone are highly important to coastal protection. However, most studies on hydrodynamic impacts of vegetation in the intertidal zone are carried out in flumes. This results in a lack of field data for validating models that describe short-term hydrodynamic impacts of vegetation. The current research focuses on field measurements of flow patterns and waves in vegetated intertidal areas. Ample measurement devices are available to measure hydrodynamic processes in the field. Examples are: acoustic Doppler current profilers (ADCP), high resolution acoustic Doppler current profilers (HR-ADCP) and acoustic Doppler velocity meters (ADV). This study focuses on the differences in the performance of these devices, to determine which of them can be best deployed in a future fieldwork campaign in mangroves. Major points of attention in this comparison are the accuracy of the data and the potential disturbance of the measurements by the presence of vegetation. It is concluded that ADV’s perform very well in vegetated intertidal areas, while (HR-)ADCP’s show difficulties when deployed upward looking. Furthermore, ADV’s are preferred over (HR-)ADCP’s due to their ability of combining high frequent wave and current measurements and their convenient deployment.
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Chapman, N. Ross, Joe F. Gettrust, Rick Walia, David Hannay, George D. Spence, Warren T. Wood, and Roy D. Hyndman. "High‐resolution, deep‐towed, multichannel seismic survey of deep‐sea gas hydrates off western Canada." GEOPHYSICS 67, no. 4 (July 2002): 1038–47. http://dx.doi.org/10.1190/1.1500364.
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A multichannel seismic survey was carried out using the high‐resolution deep‐towed acoustics/geophysics system (DTAGS) to image the structure of deep‐sea gas hydrates on the continental slope off Vancouver Island and to determine the velocity profile of the hydrated sediments. The high‐frequency DTAGS data provide the means to estimate the frequency response of the bottom simulating reflector (BSR) that defines the base of the hydrate stability field in these sediments, over a broad frequency band from 15 to 650 Hz. The DTAGS sections resolved fine‐scale layering as thin as a few meters within the hydrated zone and below the BSR, and they revealed small‐scale faults and vertically oriented zones of very low acoustic reflectivity that may represent channels for upward migration of fluids or gas. Interval velocities determined from the DTAGS data indicate uniformly low values of about 1500 m/s to depths of 100 m below sea floor (mbsf), increasing to about 1850 m/s at the BSR (250 mbsf). The reflection from the BSR that is normally well defined in conventional low‐frequency seismic surveys is at least twenty times weaker at the high DTAGS frequencies. The reflection coefficient‐versus‐frequency data support a new model for the velocity profile at the BSR that consists of a thin, 4–8‐m layer at the BSR in which the velocity decreases by 250 m/s. The thin transition layer at the BSR implies relatively high methane flux rates of at least 1.5 mm/year.
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Luo, Bin, Ariel Lellouch, Ge Jin, Biondo Biondi, and James Simmons. "Seismic inversion of shale reservoir properties using microseismic-induced guided waves recorded by distributed acoustic sensing." GEOPHYSICS 86, no. 4 (June 1, 2021): R383—R397. http://dx.doi.org/10.1190/geo2020-0607.1.
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Shale formation properties are crucial for the hydrocarbon production performance of unconventional reservoirs. Microseismic-induced guided waves, which propagate within the low-velocity shale formation, are an ideal candidate for accurate estimation of shale thickness, velocity, and anisotropy. A distributed acoustic sensing fiber deployed along the horizontal section of a monitor well can provide a high-resolution recording of guided waves excited by microseismic events during hydraulic fracturing operations. These guided waves manifest a highly dispersive behavior that allows for seismic inversion of the shale formation properties. An adaptation of the propagator matrix method is presented to estimate guided-wave dispersion curves, and its accuracy is validated by comparison to 3D elastic wavefield simulations. The propagator matrix formulation holds for cases of vertical transverse isotropy (VTI) as well. A sensitivity analysis of the theoretical dispersion relations of the guided waves indicates that they are mostly influenced by the thickness and S-wave velocity of the low-velocity shale reservoir. The VTI parameters of the formation are also shown to have an impact on the dispersion relations. These physical insights provide the foundation for a dispersion-based model inversion for a 1D depth-dependent structure of the reservoir and its surroundings. The inversion procedure is validated in a synthetic case and applied to the field records collected in an Eagle Ford hydraulic fracturing project. The inverted structure agrees well with a sonic log acquired several hundred meters away from the monitor well. Therefore, seismic inversion using guided-wave dispersion indicates promise to become a novel and cost-effective strategy for in situ estimation of reservoir structure and properties, which complements microseismic-based interpretation and production-related information.
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Mohd Remy Rozainy, M. A. Z., A. W. Khairy, Ismail Abustan, and Mohd Mustafa Al Bakri Abdullah. "Model Study for Upgrading of Sungai Belibis Pump Sump." Applied Mechanics and Materials 802 (October 2015): 617–22. http://dx.doi.org/10.4028/www.scientific.net/amm.802.617.
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Experimental study of hydraulic physical model investigates the flow characteristics in the pump sump. The model features four pumps (7.91 L/s for pump 1 and 2, and 4.74 L/s for pump 3 and 4) with a total of 9 cases of study. Different values of water depth (180mm, 200mm, and 300mm) and pump flow rate (15L/s, 20L/s, and 25L/s) were conducted. Velocity measurements at the dividing cross section were obtained by an Acoustic Doppler Velocimeter (ADV), pump flow rate by flow meter (Dyna Handheld Transit Time Ultrasonic Flow Meters) and swirl angle in the suction intakes were measured by a vortimeter/rotometer. No vortices were occurred near the suction intake at the high and medium water level conditions. In the low water level condition with high flow rate (25L/s), vortex Type 4 or 5 were observed near the suction intake and this condition is unacceptable. Since this condition indicate the presence of vortices more than Types 2 and an uneven flow through the suction intake, this can be categorized as the worst case and not recommended for pump sump operation.
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Raymond, Charles F., and Stephen Malone. "Propagating Strain Anomalies during Mini-Surges of Variegated Glacier, Alaska, U.S.A." Journal of Glaciology 32, no. 111 (1986): 178–91. http://dx.doi.org/10.1017/s0022143000015495.
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AbstractWire strain meters and seismometers spaced longitudinally along the upper part of Variegated Glacier, Alaska, showed quasi-periodic episodes of increased velocity (mini-surges), which lasted about 1 day and recurred at intervals of a few days to 2 weeks during the early part of the melt seasons of 1979, 1980, and 1981. The zone affected by these mini-surges corresponds to the zone of highest velocity and basal stress increase over the previous decade, and the initiation of the most recent surge in 1982. Mini-surges initiate locally; as a single melt season progresses, the later mini-surges start at higher locations and show a distinct down-glacier propagation of a characteristic strain pattern and associated zone of acoustic emissions at speeds of 0.1–0.6 km h−1. During mini-surges, extensile and compressive strain-rates exceed 10 × 10−4d−1and 40 × 10−4d−1, respectively; typical strain-rates between mini-surges were less than 2 × 10−4d−1in magnitude. Seismic activity jumped by two orders of magnitude and was distinctly audible during a mini-surge. Maximum strain-rate during mini-surges decreased from year to year. The high time resolution of the strain allows short time-scale structure of velocity variations to be deduced. As a propagating mini-surge passes, the velocity anomaly at a fixed location is characterized by a rapid initial rise over a few hours to two distinct peaks separated by a few hours, followed by a slower return to normal velocity taking up to a day. The double peak in velocity may arise from a single, very sharp, transient peak in the basal slip velocity associated with the initial opening of cavities at the base in response to a sudden rise in basal water pressure (observed by Kamb and Engelhardt). This supports an important role for basal cavitation in the mini-surge mechanism.
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Matsuoka, Takeshi, Seiho Uratsuka, Makoto Satake, Akitsugu Nadai, Toshihiko Umehara, Hideo Maeno, Hiroyuki Wakabayashi, Fumihiko Nishio, and Yasushi Fukamachi. "Deriving sea-ice thickness and ice types in the Sea of Okhotsk using dual-frequency airborne SAR (Pi-SAR) data." Annals of Glaciology 34 (2002): 429–34. http://dx.doi.org/10.3189/172756402781817392.
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AbstractDual-frequency, multi-polarization airborne synthetic aperture radar (Pi-SAR; developed by the Communications Research Laboratory and National Space Development Agency of Japan) observations of the seasonal sea-ice region off the Okhotsk coast of Hokkaido, Japan, were carried out in February 1999 using X- and L-band radar frequencies with a resolution of 1.5 and 3.0 m. In conjunction with the SAR observations, the sea-ice thickness (draft) and velocity were measured by a moored Ice Profiling Sonar (IPS) and an Acoustic Doppler Current Profiler (ADCP). Tracks of the sea ice passing over the IPS were estimated from the time series of the ADCP ice-velocity and -direction data. Along these tracks, the SAR backscattering coefficient profiles were compared with the IPS ice-draft profiles. The results showed that the L-band SAR backs cattering profiles correlated well with the IPS ice-draft data, particularly in the thicker part (a few meters thick) of the rim of first-year ice, which had a large backscattering coefficient. Although the X-band SAR backscattering profiles did not correlate well with the IPS data, thin ice (<10 cm thick) showed a large backscattering coefficient. The L-band SAR and IPS data did not distinguish thin ice from open water.
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Raymond, Charles F., and Stephen Malone. "Propagating Strain Anomalies during Mini-Surges of Variegated Glacier, Alaska, U.S.A." Journal of Glaciology 32, no. 111 (1986): 178–91. http://dx.doi.org/10.3189/s0022143000015495.
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AbstractWire strain meters and seismometers spaced longitudinally along the upper part of Variegated Glacier, Alaska, showed quasi-periodic episodes of increased velocity (mini-surges), which lasted about 1 day and recurred at intervals of a few days to 2 weeks during the early part of the melt seasons of 1979, 1980, and 1981. The zone affected by these mini-surges corresponds to the zone of highest velocity and basal stress increase over the previous decade, and the initiation of the most recent surge in 1982. Mini-surges initiate locally; as a single melt season progresses, the later mini-surges start at higher locations and show a distinct down-glacier propagation of a characteristic strain pattern and associated zone of acoustic emissions at speeds of 0.1–0.6 km h−1. During mini-surges, extensile and compressive strain-rates exceed 10 × 10−4 d−1 and 40 × 10−4 d−1, respectively; typical strain-rates between mini-surges were less than 2 × 10−4d−1 in magnitude. Seismic activity jumped by two orders of magnitude and was distinctly audible during a mini-surge. Maximum strain-rate during mini-surges decreased from year to year. The high time resolution of the strain allows short time-scale structure of velocity variations to be deduced. As a propagating mini-surge passes, the velocity anomaly at a fixed location is characterized by a rapid initial rise over a few hours to two distinct peaks separated by a few hours, followed by a slower return to normal velocity taking up to a day. The double peak in velocity may arise from a single, very sharp, transient peak in the basal slip velocity associated with the initial opening of cavities at the base in response to a sudden rise in basal water pressure (observed by Kamb and Engelhardt). This supports an important role for basal cavitation in the mini-surge mechanism.
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Novoselov, Artemii, Florian Fuchs, and Goetz Bokelmann. "Acoustic-to-seismic ground coupling: coupling efficiency and inferring near-surface properties." Geophysical Journal International 223, no. 1 (June 19, 2020): 144–60. http://dx.doi.org/10.1093/gji/ggaa304.
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SUMMARY A fraction of the acoustic wave energy (from the atmosphere) may couple into the ground, and it can thus be recorded as ground motion using seismometers. We have investigated this coupling, with two questions in mind, (i) how strong it is for small explosive sources and offsets up to a few tens of meters and (ii) what we can learn about the shallow subsurface from this coupling. 25 firecracker explosions and five rocket explosions were analysed using colocated seismic and infrasound sensors; we find that around 2 per cent of the acoustic energy is admitted into the ground (converted to seismic energy). Transfer coefficients are in the range of 2.85–4.06 nm Pa–1 for displacement, 1.99–2.74 μm s–1 Pa–1 for velocity, and 2.2–2.86 mm s−2 Pa–1 for acceleration. Recording dynamic air pressure together with ground motion at the same site allows identification of different waves propagating in the shallow underground, notably the seismic expression of the direct airwave, and the later air-coupled Rayleigh wave. We can reliably infer shallow ground properties from the direct airwave, in particular the two Lamé constants (λ and μ) and the Poisson ratio. Firecrackers as pressure sources allow constraining elastic parameters in the top-most layer. In this study, they provide frequency-dependent values of λ decreasing from 119 MPa for low frequencies (48 Hz) to 4.2 MPa for high frequencies (341 Hz), and μ values decreasing from 33 to 1.8 MPa. Frequency-dependent Poisson ratios ν are in the range of 0.336–0.366.
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Finn, Anthony, and Kevin Rogers. "An Acoustic Tomography Technique for Concurrently Observing the Structure of the Atmosphere and Water Bodies." Journal of Atmospheric and Oceanic Technology 34, no. 3 (March 2017): 617–29. http://dx.doi.org/10.1175/jtech-d-16-0128.1.
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AbstractThe opacity of water to radio waves means there are few, if any, techniques for remotely sensing it and the atmosphere concurrently. However, both these media are transparent to low-frequency sound (<300 Hz), which makes it possible to contemplate systems that take advantage of the natural integration along acoustic paths of signals propagating through both media. This paper proposes—and examines with theoretical analysis—a method that exploits the harmonics generated by the natural signature of a propeller-driven aircraft as it overflies an array of surface and underwater sensors. Correspondence of the projected and observed narrowband acoustic signals, which are monitored synchronously on board the aircraft and by both sensor sets, allows the exact travel time of detected rays to be related to a linear model of the constituent terms of sound speed. These observations may then be inverted using tomography to determine the inhomogeneous structures of both regions. As the signature of the aircraft comprises a series of harmonics between 50 Hz and 1 kHz, the horizontal detection limits of such a system may be up to a few hundred meters, depending on the depth of the sensors, roughness of the water surface, errors due to refraction, and magnitude of the sound field generated by the source aircraft. The approach would permit temperature, wind, and current velocity profiles to be observed both above and below the water’s surface.
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Scotti, A., B. Butman, R. C. Beardsley, P. Soupy Alexander, and S. Anderson. "A Modified Beam-to-Earth Transformation to Measure Short-Wavelength Internal Waves with an Acoustic Doppler Current Profiler." Journal of Atmospheric and Oceanic Technology 22, no. 5 (May 1, 2005): 583–91. http://dx.doi.org/10.1175/jtech1731.1.
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Abstract The algorithm used to transform velocity signals from beam coordinates to earth coordinates in an acoustic Doppler current profiler (ADCP) relies on the assumption that the currents are uniform over the horizontal distance separating the beams. This condition may be violated by (nonlinear) internal waves, which can have wavelengths as small as 100–200 m. In this case, the standard algorithm combines velocities measured at different phases of a wave and produces horizontal velocities that increasingly differ from true velocities with distance from the ADCP. Observations made in Massachusetts Bay show that currents measured with a bottom-mounted upward-looking ADCP during periods when short-wavelength internal waves are present differ significantly from currents measured by point current meters, except very close to the instrument. These periods are flagged with high error velocities by the standard ADCP algorithm. In this paper measurements from the four spatially diverging beams and the backscatter intensity signal are used to calculate the propagation direction and celerity of the internal waves. Once this information is known, a modified beam-to-earth transformation that combines appropriately lagged beam measurements can be used to obtain current estimates in earth coordinates that compare well with pointwise measurements.
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Yan, Changgen, Tong Yuan, and Kai Wang. "Unloading Phenomena Characteristics in Brittle Rock Masses by A Large-Scale Excavation in Dam Foundation." Open Civil Engineering Journal 8, no. 1 (September 4, 2014): 177–82. http://dx.doi.org/10.2174/1874149501408010177.
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Xiaowan Hydropower station’s dam located in south west of China is the second highest arch dam in the world (h = 292 m), its foundation is based on brittle rocks of biotite granite gneiss and amphibolites plagioclase gneiss. A large-scale excavation around the foundation of the dam was conducted, near to 90 meters horizontal depth excavation and 130 meters vertical depth excavation, so the foundation dam was marked by a significant deformation and a severe damage near the excavation zone, namely excavation distributed zone (EDZ). This damage was caused by the unloading process. According to the in situ investigation, the characteristics of unloading rock masses were described. With the acoustic wave velocity monitoring method, the unloading rock masses characteristics of time effect and space distribution are summarized. Usually the unloading process causes fractures in rock masses along two perpendicular directions in the plane of the bank slope, one is parallel to the dam base slope, and the other is parallel to the river with steep-dip angle. Near to the excavation surface, the excavation damage are more serious, and from the high elevation area to low elevation area, the damage caused by unloading are becoming stronger and stronger, and the bottom of dam base is most damaged. The unloading deformation has a direct temporal dependence; in general, after the excavation, the unloading deformation increases quickly during the firsts 90 days, and increase by a slow rate from 90 to 180 days and after that the unloading deformation will be small enough to be neglected.
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Al-Haq, Muhammad Imran, Junichi Sugiyama, Akiko Tomizawa, and Yasuyuki Sagara. "Nondestructive Acoustic Firmness Tester Detects the Effect of Manure on Muskmelon Texture." HortScience 39, no. 1 (February 2004): 142–45. http://dx.doi.org/10.21273/hortsci.39.1.142.
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The effect of amount of manure (animal dung) on the texture of muskmelons (Cucumis melo L.) has been studied. Melons were grown in a greenhouse with 20 and 50 t·ha-1 of manure. Melons were harvested four times at 4-day intervals and kept at ambient conditions for about 8-12 days. Texture was determined by using “Firm Tester” that employs acoustic technology and to provide a firmness index expressed as transmission velocity [meters per second (m/s)]. At the time of the first, second, third and fourth harvest the fruit grown with 20 t·ha-1 manure gave mean transmission velocities of 54.5 ± 2.5, 55.2 ± 5.7, 49.6 ± 4.8, and 46.8 ± 9.4 m/s, respectively. Linear regression equations for fruit grown with 20 t·ha-1 manure showed that the fruit from the first harvest took 10 days to reach 40 m/s, while fruit from the second, third and fourth harvest took 11, 9.5, and 4 days, respectively, to reach this index. The corresponding values for fruit grown in 50 t·ha-1 of manure were 7.5, 10, 5.5 and 4.5 days, those from the second harvest gave the best keeping quality. The firmness index of melon grown in 20 t·ha-1 of manure was greater than that grown in 50 t·ha-1 manure. Higher soil NO3-N contents were associated with softer melons. The correlation between panelist scores for texture and the firmness index was 0.907. Both °Brix and panelist scores for sweetness indicated that manure did not affect the sweetness of melon. The digital firmness tester could detect the effect of manure on the texture of the melons, and could be used to determine the appropriate time of harvest for each and every individual melon.
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Yulius, Yulius, Joko Prihantono, Dino Gunawan, Muhammad Ramdhan, August Daulat, and Nur Kholik Kurniana Putra. "Hydro-Oceanographic Characteristics In Karimunjawa Coastal Waters During The 1st Transitional Season." Jurnal Segara 17, no. 2 (November 12, 2021): 107. http://dx.doi.org/10.15578/segara.v17i2.9839.
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This study aims to determine oceanographic characteristics such as tides, waves, and currents in Karimunjawa Coastal Waters during the 1st transitional season and to update the oceanographic database for spatial management evaluation in the region. The tidal characteristics were obtained from the least square method analysis using World Tide software based on Matlab programming language, while wave and current characteristics obtained from 2-dimensional numerical modeling using Mike 21 software on the flow model and spectral wave module. The primary data used were the significant wave height (Hs), wave peak period (Tp), and ocean current components (u and v velocity) on 13-26 May 2016 using the Sontex Argonaut XR type Acoustic Doppler Current Profiler (ADCP) equipment. Tide data were predicted for the Kemujan Islands station from 1-31 March 2020. Secondary data for additional numerical model input were obtained from ERA5-reanalysis in the form of Hs, Tp, u, and v wind velocity data for May 2020 with a temporal resolution of 20 minutes, while bathymetry data derived from GEBCO Satellite Derivated Bathymetry (SDB) data. The tide analysis results showed that Karimunjawa waters are a single daily mixed tidal type. The wave characteristic moves from east to west with high waves reached 0.9 meters and a peak period of 7 seconds. The eastern side of Karimunjawa Island, Kemujan Island, and the western area have a calmer wave. The current characteristic moves northeastward with a speed of 5-28 cm/s, which concludes that in several locations, such as the Menjangan Besar-Menjangan Kecil strait, the currents depend on the tidal conditions.
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Bergamasco, A., V. Defendi, and R. Meloni. "Some dynamics of water outflow from beneath the Ross Ice Shelf during 1995 and 1996." Antarctic Science 14, no. 1 (March 2002): 74–82. http://dx.doi.org/10.1017/s0954102002000603.
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The paper presents two years of observations (1995 and 1996) for water velocity and temperature near the Ross Ice Shelf edge, where a mooring, composed of three current meters, five temperature and three conductivity sensors, one turbidimeter, two sediment traps and one Acoustic Doppler Current Profiler, was deployed. The mooring site was chosen to study the behaviour of the Ice Shelf Water, within the framework of the Project on the Climatic Long-term Interaction for the Mass balance in Antarctica of the Italian National Programme for Antarctic Research. The Ice Shelf Water outflow from below the Ross Ice Shelf is a persistent phenomenon in this area, but it is characterized by impulsive injections often associated with recirculation processes. Two years of data records of physical variables are investigated here in order to analyse the Ice Shelf Water outflow behaviour and to give an estimate of this feature. Our results show that the Ice Shelf Water events have variable duration (from one to seven days) and present an interannual variability in their timing. In spite of this, the mean Ice Shelf Water outflow during the overlapping period of the two time series is quite similar: 0.15 Sv for 1995 and 0.28 Sv for 1996.
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Clément, L., E. Frajka-Williams, K. L. Sheen, J. A. Brearley, and A. C. Naveira Garabato. "Generation of Internal Waves by Eddies Impinging on the Western Boundary of the North Atlantic." Journal of Physical Oceanography 46, no. 4 (April 2016): 1067–79. http://dx.doi.org/10.1175/jpo-d-14-0241.1.
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AbstractDespite the major role played by mesoscale eddies in redistributing the energy of the large-scale circulation, our understanding of their dissipation is still incomplete. This study investigates the generation of internal waves by decaying eddies in the North Atlantic western boundary. The eddy presence and decay are measured from the altimetric surface relative vorticity associated with an array of full-depth current meters extending ~100 km offshore at 26.5°N. In addition, internal waves are analyzed over a topographic rise from 2-yr high-frequency measurements of an acoustic Doppler current profiler (ADCP), which is located 13 km offshore in 600-m deep water. Despite an apparent polarity independence of the eddy decay observed from altimetric data, the flow in the deepest 100 m is enhanced for anticyclones (25.2 cm s−1) compared with cyclones (−4.7 cm s−1). Accordingly, the internal wave field is sensitive to this polarity-dependent deep velocity. This is apparent from the eddy-modulated enhanced dissipation rate, which is obtained from a finescale parameterization and exceeds 10−9 W kg−1 for near-bottom flows greater than 8 cm s−1. The present study underlines the importance of oceanic western boundaries for removing the energy of low-mode westward-propagating eddies to higher-mode internal waves.
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Lucas, N. S., J. H. Simpson, T. P. Rippeth, and C. P. Old. "Measuring Turbulent Dissipation Using a Tethered ADCP." Journal of Atmospheric and Oceanic Technology 31, no. 8 (August 1, 2014): 1826–37. http://dx.doi.org/10.1175/jtech-d-13-00198.1.
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Abstract The structure function method for estimating the dissipation rate of turbulent kinetic energy, previously validated for measurements from seabed fixed mounts, is applied to data from 1.2-MHz acoustic Doppler current profiler (ADCP) instruments operating in pulse–pulse coherent mode and mounted in midwater below a tethered buoy. Movements of the buoy introduce additional relative velocity components, but it is hypothesized that these flow components should not seriously interfere with the turbulence information because (i) horizontal or vertical translation induces the same flow component in all cells of an ADCP beam and (ii) any rotation of the instrument about its center induces flow components that are normal to the beam direction, and thus neither affect the structure function. This hypothesis is tested by comparing a series of dissipation measurements from a moored ADCP with those from a free-falling Vertical Microstructure Profiler (VMP) shear probe deployed from a nearby research vessel. The results indicate generally good conformity in both mean and variability over almost two decades of dissipation rates. The noise level of the structure function estimates with the pulse–pulse coherent ADCP is close to that of the VMP at ~3 × 10−10 W kg−1. This approach offers the prospect of long time series measurements of dissipation rate from moorings, albeit with restricted vertical range of a few meters.
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M.Aminuddin, Normadihah, Safari Mat Desa, Suriani Awang, Nasehir Khan E.M. Yahaya, Norbaya Hashim, Liew Yuk San, Siti Nor Fazillah Abdullah, and Nur Hanis Mohamad Hanapi. "An Assessment of the Potential, Suitability and Sustainability of the Sand Mining Site in the Kemaman River Basin, Terengganu Using Acoustic Doppler Current Profiler." Malaysian Journal of Applied Sciences 6, no. 2 (October 31, 2021): 48–60. http://dx.doi.org/10.37231/myjas.2021.6.2.308.
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Sand mining from the catchment basin for building is a worldwide issue. The increasing demand for sand in the construction industry has led sand suppliers to look for alternative methods by which they can obtain source of sand from the riverbed. Floodplain and river slabs can be used as new sources of sand mining. In Sungai Kemaman, during September until March a high precipitation can cause high flow in river. This high flow can cause riverbank erosion which leads to instability of river. Therefore, river erosion can probably be reduced by identifying the potential area for sand mining. This research was conducted to analyse sand capability on floodplain and riverbed by integrating resistivity method and sediment transport loads using Acoustic Doppler Current Profiler (ADCP). Resistivity survey is used in determining the availability of potential soil at the study area and the equipment could measure subsurface profile up to 80 meters depth. Meanwhile, ADCP survey is utilized to make river profiler in term of velocity meshes and riverbed depth. The primary data collected was from 20 January 2014 to 19 February 2014. The findings found that the samples trapped in the Helly-Smith grabber were majority of the samples consisted more than 93% of gravel and sand materials and from the resistivity analysis, it is verified that the surrounding materials along the Sungai Kemaman is sandy material and high potential of the sand mining site.
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Venosa, Albert D., Vikram J. Kaku, Michel C. Boufadel, and Kenneth Lee. "MEASURING ENERGY DISSIPATION RATES IN A WAVE TANK." International Oil Spill Conference Proceedings 2005, no. 1 (May 1, 2005): 183–86. http://dx.doi.org/10.7901/2169-3358-2005-1-183.
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ABSTRACT The effectiveness of dispersants is typically evaluated at various scales ranging from the smallest (10 cm, typical of flask tests in the laboratory) to the largest (10's to 100's of meters, typical of field scale open water dispersion tests). This study aims at evaluating dispersant effectiveness at intermediate or pilot scale. The hypothesis is that the energy dissipation rate per unit mass, ɛ, plays a major role in the effectiveness of a dispersant. Therefore, it is stipulated that in fairly general conditions, conservation of ɛ between the wave tank scale and that of the field scale is sufficient to accurately evaluate the effectiveness of a dispersant to disperse oil droplets. A wave tank measuring 16 m long x 0.6 m wide x 2 m deep was constructed on the premises of the Bedford Institute of Oceanography, Halifax, Nova Scotia. Waves were generated using a flap-type wave maker. Conditions of the breaking waves were created using a dispersive focusing technique in which the wave maker is started at high frequency and then the frequency decreased to create breaking waves. Experiments defining the velocity profile and energy dissipation rates in the wave tank were conducted at 2 different induced breaking-wave energies. Energy in the wave tank was measured with an Acoustic Doppler Velocimeter (ADV) coupled to a data acquisition system. Energy in the lab flasks was measured with a Hot Wire Anemometer.
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Ritzwoller, Michael H., and Anatoli L. Levshin. "Estimating shallow shear velocities with marine multicomponent seismic data." GEOPHYSICS 67, no. 6 (November 2002): 1991–2004. http://dx.doi.org/10.1190/1.1527099.
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Accurate models of shear velocities in the shallow subsurface (<300 m depth beneath the sea floor) would help to focus images of structural discontinuities constructed, for example, with P to S converted phases in marine environments. Although multicomponent marine seismic data hold a wealth of information about shear velocities from the sea floor to depths of hundreds of meters, this information remains largely unexploited in oil and gas exploration. We present a method, called the multiwave inversion (MWI) method, designed to use a wide variety of information in marine seismic data. As presented here, MWI jointly uses the observed traveltimes of P and S refracted waves, the group and phase velocities of fundamental mode and first overtone interface waves, and the group velocities of guided waves to infer shear velocities and Vp/Vs ratios. We show how to obtain measurements of the traveltimes of these diverse and, in some cases, dispersive waves and how they are used in the MWI method to estimate shallow shear velocities. We illuminate the method with synthetic and real multicomponent marine data and apply MWI to some real data to obtain a model of Vs with uncertainty estimates to a depth of 225 m and Vp/Vs to about 100‐m depth. We conclude by discussing the design of offshore surveys necessary to provide information about shallow shear‐velocity structures, with particular emphasis on the height of the acoustic source above the sea floor.
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Jiang, Hongxu, Yalin Li, Yongwei Liu, and Dejiang Shang. "The system design for calibrating acoustic Doppler current meter in the laboratory." MATEC Web of Conferences 283 (2019): 08001. http://dx.doi.org/10.1051/matecconf/201928308001.
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The Acoustic Doppler Current meter is a most commonly device for the velocity measurement of the seawater in the ocean. We had designed an equipment to calibrate the Acoustic Doppler Current meter in the laboratory, which is mainly composed of a vertical circulating water tank and a system of Laser Doppler Velocimetry. The vertical circulating water tank is the key device of the calibration equipment. The optimization of flow field is carried out by the software, CFD. The optimization of structure intensity, modal analysis and low noise is carried out by the software, ANSYS. We had also used the propeller map to design the power section of the water tank. Through the comparison of the velocity of the flow between Acoustic Doppler Current meter and LDV at the same position in the working section of the water tank, the former can be calibrated, because the wavelength of optics is much less than that of acoustics in the water. After the experimental test, we found that when the fluid flows in the vertical circulating water tank, there exists no resonance phenomenon and the velocity of the flow in the working section is approximately proportional to the rotation speed of the propeller.
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Guinasso, Norman L., John N. Walpert, Linwood L. Lee, Steven F. DiMarco, and Steven Buschang. "TEXAS AUTOMATED BUOY SYSTEM PROVIDES SITUATIONAL AWARENESS OF WINDS AND CURRENTS ON THE COAST OF TEXAS." International Oil Spill Conference Proceedings 2014, no. 1 (May 1, 2014): 300175. http://dx.doi.org/10.7901/2169-3358-2014-1-300175.1.
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Texas has established an operational system that provides observations of wind and currents to the State On-Scene Coordinator. The Texas Automated Buoy System (TABS) began in 1994 with five current meter buoys. Buoys measure current velocity 2m below the surface and transmit data on a regular schedule via satellite communications. Most buoys measure winds using acoustic wind sensors and some buoys are configured with profiling current meters. Larger buoys use solid-state accelerometers to measure waves. Buoys use solar panels to charge lead-acid batteries and can operate unattended for periods up to a year with the limitation being summertime biological fouling. TABS makes use of six different types of buoys with each filling its own particular niche to support trajectory modeling. These include TABS I, II, 2.25m and 3m buoys. A new coastal monitoring buoy (CMB) is a 1.4m solar charged buoy designed for extended operation in shallow water to measure current profiles, waves and MET data. The TABS Responder is a small, lightweight, rechargeable buoy designed for short deployments from any vessel of opportunity at the site of an oil spill. Designed for shallow water (<40m), the buoy measures waves, current profiles and meteorological data. GERG has a fleet of four Responder buoys that will be capable of deployment with short notice in the event of an emergency. Data from the buoys are transmitted to computers at College station TX where they undergo automated quality control before posting on a dedicated web page. Data are disseminated via the internet to the state and federal governments. Public presentation of the data takes place in three different time frames. Data are available in near real time on a web page that displays data for the past four days. A Real Time Analysis program process the data every 24 hours and presents a series of data products including stick plots, current and wind roses, and distribution tables. A monthly Hindcast Analysis looks at the previous month's data, performs additional quality control, and prepares final plots. Finally a monthly Climatology program produces climatological summaries of the all data by month and year.
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Edmund, Eric, Michel Gauthier, Daniele Antonangeli, Simon Ayrinhac, Silvia Boccato, Thibault Deletang, Marc Morand, Yiuri Garino, Paraskevas Parisiades, and Frédéric Decremps. "Picosecond Acoustics Technique to Measure the Sound Velocities of Fe-Si Alloys and Si Single-Crystals at High Pressure." Minerals 10, no. 3 (February 27, 2020): 214. http://dx.doi.org/10.3390/min10030214.
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We describe here a time resolved pump-probe laser technique—picosecond interferometry—which has been combined with diamond anvil cells (DAC). This method enables the measurement of the longitudinal sound velocity up to Mbar pressure for any kind of material (solids, liquids, metals, insulators). We also provide a description of picosecond acoustics data analysis in order to determine the complete set of elastic constants for single crystals. To illustrate such capabilities, results are given on the pressure dependence of the acoustic properties for prototypical cases: polycrystal (hcp-Fe-5 wt% Si up to 115 GPa) and single-crystal (Si up to 10 GPa).
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Doering, John C., and Kevin D. Gawne. "Acoustic discharge measurements for the performance testing of low-head hydroelectric turbines under disturbed flow conditions." Canadian Journal of Civil Engineering 27, no. 1 (February 15, 2000): 160–65. http://dx.doi.org/10.1139/l99-066.
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Field performance testing of a low-head hydroelectric turbine is essential to evaluate the efficiency and economics of an operation. For low-head hydroelectric turbines, it is difficult to accurately measure the discharge through a unit. Transit-time velocity measurement technology has recently been used to develop, in a laboratory setting, a unique traversing acoustic discharge meter for low-head hydroelectric applications. This technology was recently combined with Gauss-Legendre quadrature integration as an alternative method of measuring the flow through a low-head hydroelectric turbine. However, laboratory testing of this technology has only dealt with undisturbed or ideal flow conditions. Additional physical modeling has been performed to compare the relative accuracy of the continuous traversing acoustic discharge meter with that of a multilevel Gauss-Legendre quadrature integration in disturbed or nonideal flow conditions. The data indicate that while Gauss-Legendre quadrature may provide more accurate estimates in ideal flow conditions, the continuous traversing acoustic discharge meter is better suited to disturbed flow condition because it can better resolve an intricate velocity profile. The accuracy of this instrumentation is sensitive to relatively large scale vorticity rotating in the plane of the acoustic transducers, although accuracies within 2% are still attainable, which is better than the conventional velocity-area method. Key words: acoustic discharge measurement, disturbed flow, turbine, performance testing.
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Katakura, Kageyoshi. "Ultrasonic velocity meter." Journal of the Acoustical Society of America 85, no. 1 (January 1989): 528–29. http://dx.doi.org/10.1121/1.397992.
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Doering, John C., and Kevin D. Gawne. "Developing a traversing acoustic discharge measurement technique for the performance testing of low-head hydroelectric turbines." Canadian Journal of Civil Engineering 25, no. 4 (August 1, 1998): 777–88. http://dx.doi.org/10.1139/l98-014.
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The efficient operation of a hydroelectric generating plant requires an accurate definition of the performance relationships for each turbine-generator unit. Of the information obtained during performance testing, discharge is the most difficult to measure accurately. Acoustic transit-time velocity measurement technology is applied herein to obtain more accurate discharge measurements than current velocity - area method practices. The technique proposed involves continuously traversing a number of acoustic paths, each providing a chordal average velocity measurement, across the turbine intake to obtain a complete integration of the complex velocity profile typical of low-head hydroelectric plants. Data from hydraulic laboratory testing of a single acoustic cell were compared with known flow rates to assess the accuracy and repeatability of the proposed discharge measurement technique. A range of continuous traverse rates was evaluated. The results indicate that the proposed continuous traversing acoustic discharge meter (TADM) can provide efficient, accurate (1-2% error), and repeatable discharge measurements.Key words: turbine, performance testing, acoustic discharge measurement, traversing.
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Allafchi, Farzam, Caterina Valeo, Angus Chu, Jianxun He, Waltfred Lee, Peter Oshkai, and Norman Neumann. "A Velocity Meter for Quantifying Advection Velocity Vectors in Large Water Bodies." Sensors 20, no. 24 (December 16, 2020): 7204. http://dx.doi.org/10.3390/s20247204.
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A velocity meter was designed and built in order to meet market needs for an affordable instrument that measures the range of velocity magnitudes and direction experienced in medium- to large-sized water bodies. The velocity meter consists of a graduated plate with an injector protruding from the center and a camera held downward above the plate. Once the Dye Injection Velocity (DIV) meter is in the flow, dye is injected and the camera records the dye fluid transport. The recorded video is analyzed to determine the local flow velocity and direction. The DIV was calibrated for a range of velocities between 0.0094 m/s and 0.1566 m/s using particle image velocimetry (PIV) in a flow visualization flume. The accuracy of the instrument was found to be +6.3% and −9.8% of full scale. The coefficient of determination of the calibration curve was equal to 98%. Once calibrated, the DIV was deployed to the Inverness Stormwater pond in Calgary, Canada, for validation tests against an Acoustic Doppler Velocity (ADV) meter. During the validation tests, both flow velocity magnitude and direction were measured at several spatial points. The velocity magnitude results showed good agreement and the Mann-Whitney test showed no statistically significant difference (p-value > 0.05). At two spatial points, the differences between direction data were significant, which could be caused by the random errors involved in the validation test. However, the averaged data showed good agreement.
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Kushnir, V. M. "An acoustic current velocity meter for position instruments and probes." Physical Oceanography 7, no. 2 (March 1996): 149–57. http://dx.doi.org/10.1007/bf02509817.
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Beckwith, Christopher, Georgi Djambazov, Koulis Pericleous, Tungky Subroto, Dmitry G. Eskin, Dan Roberts, Ivan Skalicky, and Iakovos Tzanakis. "Multiphysics Modelling of Ultrasonic Melt Treatment in the Hot-Top and Launder during Direct-Chill Casting: Path to Indirect Microstructure Simulation." Metals 11, no. 5 (April 21, 2021): 674. http://dx.doi.org/10.3390/met11050674.
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This study concerns the numerical simulation of two competing ultrasonic treatment (UST) strategies for microstructure refinement in the direct-chill (DC) casting of aluminium alloys. In the first, more conventional, case, the sonotrode vibrating at 17.3 kHz is immersed in the hop-top to treat the sump melt pool, in the second case, the sonotrode is inserted between baffles in the launder. It is known that microstructure refinement depends on the intensity of acoustic cavitation and the residence time of the treated fluid in the cavitation zone. The geometry, acoustic field intensity, induced flow velocities, and local temperature are factors which affect this treatment. The mathematical model developed in this work couples flow velocity, acoustics modified by cavitation, heat transfer, and solidification at the macroscale, with Lagrangian refiner particles, used to determine: (a) their residence time in the active zones, and (b) their eventual distribution in the sump as a function of the velocity field. This is the first attempt at using particle models as an efficient, though indirect, alternative to microstructure simulation, and the results indicate that UST in the launder, assisted with baffle separators, yields a more uniform distribution of refining particles, avoiding the strong acoustic streaming jet that, otherwise, accompanies hot-top treatment, and may lead to the strong segregation of refining particles. Experiments conducted in parallel to the numerical studies in this work appeared to support the results obtained in the simulation.
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Kim, Noh Yu, Hwan Seon Nah, and Sang Soon Lee. "Characterization of Material Degradation in Epoxy Film Based on Scanning Acoustic Microscopy (SAM)." Key Engineering Materials 321-323 (October 2006): 578–81. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.578.
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In order to evaluate the degradation of the epoxy coating in nuclear power plants, acoustic wave velocities of epoxy films are measured using defocused scanning acoustic microscopy system(SAM). Unlike metals, the surface of the epoxy coating on the concrete liner is so thin and wavy that the conventional ultrasonic techniques for acoustic velocity of epoxy coating are hard to apply. Acoustic velocities of bulk waves are determined from V(z,t) curves of mode-converted waves generated in the film by SAM. Epoxy films are fabricated and degraded under various accelerated aging conditions, and both of longitudinal and shear wave velocities of the epoxy film are measured. Approximately 10% of reduction in acoustic wave velocity is observed from experimental results when the aging is developed fully in epoxy films. It is also found that longitudinal wave is more sensitive to deterioration of epoxy coating than transverse wave.
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Mokryy, Oleh, and Oleksandr Tsyrulnyk. "Technique for Measuring Spatial Distribution of the Surface Acoustic Wave Velocity in Metals." Archives of Acoustics 41, no. 4 (December 1, 2016): 741–46. http://dx.doi.org/10.1515/aoa-2016-0071.
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Abstract In this paper a possibility of determining a local velocity of the surface acoustic Rayleigh waves using a transducer, with the rigidly connected emitting and receiving parts, is considered. A problem on spatial resolution of such a transducer for investigation of inhomogeneous specimens is also examined. A high spatial resolution can be obtained due to the transducer displacement by a value less than the distance between the emitting and receiving parts. It is shown that in this case it is not necessary to measure the transducer displacement with a high accuracy for precise determination of the velocity. Such an effect is obtained through measuring the velocity of surface waves in one local region of the specimen with respect to the other. The criterion for optimal spatial resolution selection during spatially inhomogeneous specimens study is also proposed. The proposed criterion use is illustrated on the example of the determination of spatial distribution of the surface acoustic velocity in a steel specimen subjected to inhomogeneous plastic deformation.
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Kurniadi, Deddy. "Transit Time Multipath Ultrasonic Flowmeter: An Issue on Acoustic Path Arrangement." Applied Mechanics and Materials 771 (July 2015): 3–8. http://dx.doi.org/10.4028/www.scientific.net/amm.771.3.
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The multipath ultrasonic flow meter using transit time measurement is being widely used for industrial gas flow measurement. Since the AGA report no. 9 has released, the application of this flowmeter in natural gas metering system has become a technical standard. Currently, the commerical multipath ultrasonic flowmeter employs parallel acoustic path arrangement which consists of four, five or six pairs of ultrasonic transducer. This paper discusses an issue on the acoustic path arrangement of multipath ultrasonic flowmeter in an asymmetric flow profile. From this study, the parallel path arrangement gives relatively inconsistent measurement results when the flow velocity profile was asymmetric.
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Smyk, Emil, Paweł Gil, Rafał Gałek, and Łukasz Przeszłowski. "Acoustic and Flow Aspects of Novel Synthetic Jet Actuator." Actuators 9, no. 4 (October 9, 2020): 100. http://dx.doi.org/10.3390/act9040100.
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The acoustic and flow aspects of the novel synthetic jet actuator (SJA) with fins inside the cavity were experimentally investigated for three types of enclosure design and two models of loudspeaker. The aim of the study is to find the parameter which connects the flow and acoustic properties of the SJA and allows us to choose the optimal solution in those regards. The hot wire anemometry was used for the velocity measurements and the sound pressure level was measured with a sound level meter. The model of the loudspeaker turned out to have a significantly stronger impact on the flow parameters and noise level than the shape of the fins in the cavity. The parameter that showed a dependence on the shape of the fins was the actuator’s efficiency. A ratio of the root-mean-square velocity at the orifice axis to the sound pressure level (U0.c/SPL) was used to connect the acoustic and flow properties of the tested actuators. This parameter was subsequently applied to determine the best configuration among the tested actuators.
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Ma, Y., W. K. Van Moorhem, and R. W. Shorthill. "An Innovative Method of Investigating the Role of Turbulence in the Velocity Coupling Phenomenon." Journal of Vibration and Acoustics 112, no. 4 (October 1, 1990): 550–55. http://dx.doi.org/10.1115/1.2930141.
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An investigation has been conducted of the velocity coupling phenomenon reported in acoustically unstable solid propellant rocket motors. An innovative simulation facility has been built using solid carbon dioxide as the simulated propellant. The use of dry ice allows us to focus directly on the fluid mechanical aspect of the problem. Dry ice is contained in a two-meter long chamber. The acoustic disturbance in the chamber is introduced by means of a mechanically driven piston. Mass flow rate and acoustic pressure measurements indicate the existence of a coupling mechanism, other than pressure coupling, between the acoustic disturbance and dry ice sublimation process. Flow visualization using a high speed camera shows a high degree of mixing, near resonance, within the flow above the dry ice surface. The flow over the dry ice is very chaotic, probably turbulent. Hot film anemometry measurements show a broad-band spectrum at low frequencies with strong peaks at the driving frequency and its harmonics near resonance. A broad band spectrum is generally taken as an indication of turbulent flow. Acoustically induced turbulent forced convection is believed to be responsible for the increase in the sublimation rate of the dry ice (simulated burning of the propellant). We believe that turbulence is one of the principal mechanisms in the velocity coupling phenomenon.
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Hay, Alex E., Len Zedel, Angus Creech, Mahdi Razaz, and Kiyosi Kawanisi. "Acoustic tomography measurement and large-eddy simulation of macroturbulence in high flow tidal channels." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A151. http://dx.doi.org/10.1121/10.0015856.
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Velocity spectra from a pilot tomography experiment in Grand Passage, Nova Scotia, exhibit the structure at 10 m to several 100 m scales similar to that of the spectra of vertically integrated velocity registered by bottom-mounted acoustic Doppler profilers. The experiment was motivated in part by the need for flow and turbulence measurement at sites being targeted for in-stream tidal power development, and by the potential of acoustic tomography for providing this information from shore-based locations in near real time. The measurements were made using a single pair of acoustic transceivers operating at 7 kHz and separated by 1.5 km at an oblique angle to the channel axis. Limited to a single cross-channel path, the experiment provided no information on the spatial structure of the turbulence. In order to investigate this structure, virtual tomographic experiments were carried out by propagating pulses through with meter-scale resolution velocity fields from a non-hydrostatic large-eddy simulation (LES) model of flow in Grand Passage. Results from these virtual experiments are presented, and their implications are discussed in relation to the potential of multi-transceiver tomography for macro-turbulence measurement and the role of horizontal shear in macro-turbulence production in coastal environments.
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Lebon, Bruno, Iakovos Tzanakis, Koulis Pericleous, and Dmitry Eskin. "Numerical Modelling of the Ultrasonic Treatment of Aluminium Melts: An Overview of Recent Advances." Materials 12, no. 19 (October 6, 2019): 3262. http://dx.doi.org/10.3390/ma12193262.
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The prediction of the acoustic pressure field and associated streaming is of paramount importance to ultrasonic melt processing. Hence, the last decade has witnessed the emergence of various numerical models for predicting acoustic pressures and velocity fields in liquid metals subject to ultrasonic excitation at large amplitudes. This paper summarizes recent research, arguably the state of the art, and suggests best practice guidelines in acoustic cavitation modelling as applied to aluminium melts. We also present the remaining challenges that are to be addressed to pave the way for a reliable and complete working numerical package that can assist in scaling up this promising technology.
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Chen, Shizhe, Yushang Wu, Shixuan Liu, Yingdong Yang, Xiaozheng Wan, Xianglong Yang, Keke Zhang, Bo Wang, and Xingkui Yan. "Development of Electromagnetic Current Meter for Marine Environment." Journal of Marine Science and Engineering 11, no. 1 (January 12, 2023): 206. http://dx.doi.org/10.3390/jmse11010206.
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Ocean current is one of the most important parameters in ocean observation, and ocean current measurement based on electromagnetic induction is becoming more and more important because of its advantages such as simple structure and high measurement accuracy. However, it is difficult to detect weak current signals in a complex marine environment. In this paper, an electromagnetic induction current measurement scheme based on lock-in amplification technology is proposed. Key technologies such as the evaluation of induced current intensity, overall design, circuit design, and orientation design of the current meter were studied. The prototype of the electromagnetic current meter was developed and tested in the laboratory and at sea. The repeatability of current velocity and current direction was higher than 1.5 cm/s and 1.5°, respectively. A comparison test between the electromagnetic current meter prototype and Nortek ADCP (Acoustic Doppler Current Profiler) installed on a buoy at sea was carried out, and the correlation coefficients of the current velocity and current direction datum were 0.90 and 0.96, respectively. Through continuous on-site and fault-free operations at sea, the experimental data show that the electromagnetic current meter has good adaptability at sea, which provides feasible technical and equipment support for ocean current observation.
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Kim, Yeonsu, Sungryul Oh, Seungsoo Lee, Jisun Byun, and Hyunuk An. "Application of Stage-Fall-Discharge Rating Curves to a Reservoir Based on Acoustic Doppler Velocity Meter Measurement Data." Water 13, no. 17 (September 5, 2021): 2443. http://dx.doi.org/10.3390/w13172443.
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The applicability of the stage-fall-discharge (SFD) method in combination with acoustic Doppler velocity meter (ADVM) data, upstream of a hydraulic structure, specifically, the Sejong-weir located in the Geum River, Korea, was examined. We developed three rating curves: a conventional simple rating curve with the data measured using an acoustic Doppler current profiler (ADCP) and floating objects, an SFD rating curve with the data measured using the ADCP and floating objects, and an SFD rating curve with the data measured using an ADVM. Because of the gate operation effect, every rating curve involved many uncertainties under 1000 m3/s (3.13 m2/s, specific discharge). In terms of the hydrograph reconstruction, compared with the conventional simple rating curve, the SFD developed using ADVM data exhibited a higher agreement with the measured data in terms of the pattern. Furthermore, the measured discharge over 1000 m3/s primarily ranged between 97.5% and 2.5% in the graph comparing the ratio of the median and observed discharge. Based on this experiment, it is confirmed that the SFD rating curve with data to represent the backwater effect, such as ADVM data, can reduce the uncertainties induced by the typical rating curve
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Kim, Noh Yu, and Cheol Kyou Lee. "Simultaneous Measurement of Longitudinal and Transverse Waves Velocities Employing Spherically Focused Acoustic Transducer." Key Engineering Materials 321-323 (October 2006): 574–77. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.574.
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Scanning acoustic microscopy (SAM) has been applied successfully to measure leaky surface wave(LSAW) velocity from V(z) curve for material characterization. Besides LSAW, SAM produces a variety of wave modes in the material propagating with different phase speeds and features, one of which is the mode-converted ultrasound. In this paper, a novel method for simultaneous measurement of longitudinal and transverse acoustic wave velocities using the mode-converted ultrasound is developed and studied at SAM. Each ultrasound arriving at the acoustic lens with different speed and phase (or time-of-flight (TOF)) is measured by the defocused transducer to calculate longitudinal and transverse wave velocities. Simple mathematical ray analysis for the mode conversion is conducted to determine the relationship of acoustic velocities with TOF of the waves in plate. Experimental results for metals and glass show that the longitudinal and transverse wave velocities measured by the proposed method are as accurate as maximum 3% in error.
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Mari, Jean-Luc, Frederick Delay, Gilles Porel, and Pierre Gaudiani. "Characterizing flow in the first hundred-meter depth of a fractured aquifer using hybrid seismic methods, acoustic logging, and flow-log measurements." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 76 (2021): 62. http://dx.doi.org/10.2516/ogst/2021048.
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Understanding subsurface flow, especially in fractured rocks only housing water through a few preferential pathways, is still challenging. The point is mainly associated with the poor accessibility of the subsurface and the lack of accurate representations for both heterogeneity and spatial distribution of water bearing bodies. This notwithstanding, highly-resolved geophysical investigations bring new images of the subsurface. This is exemplified over a fractured limestone aquifer at the site scale (for example, that of the radius of influence of an extraction well). On an experimental site, situated in the Cher region (France), two boreholes have been drilled for field experiments. Full Waveform Acoustic Logging (FWAL) and seismic experiments were conducted. Hybrid seismic imaging, which consists in combining refraction and reflection seismic results, has been carried out. Based on a four-step procedure, the processing of refracted and reflected waves provided two sections. After assemblage, these sections produced in a first step an extended time reflectivity section starting from the surface and, in a second step, a section over depth after calibration with Vertical Seismic Profile (VSP) and acoustic data. However, even the Very High Resolution (VHR) seismic methods do not have a sufficient vertical resolution to describe accurately the geological formation. The acoustic sections were processed to separate the different wave fields, to extract the criss-cross events and to build a criss-cross index log. A log of fracturation index, based on both criss-cross index and P-wave velocity measurements, was computed to detect the presence of fractures. After calibration, and under the assumption that the slower the P-wave velocity, the higher the permeability – porosity, a 3D seismic block of reflection can inform on preferential areas where flow should occur. At the scale of an open wellbore, acoustic loggings that measure wave velocities over a short distance within the well also inform on open features crosscut by the well. Finally, flow log measurements confirm the occurrence of flowing horizons that were previously marked by both seismic and acoustic data. Seismic and acoustic data are therefore suited to image contrasted hydraulic properties over fractured subsurface systems usually poorly documented.
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Guo, Shi Sheng, Ying Shang, Xiao Hui Liu, Chang Wang, Wen An Zhao, and Jing Sheng Lv. "Design for a New Type of Water Cut Meter Based on Fiber Optic Interferometer Used in Oil Well Logging." Advanced Materials Research 807-809 (September 2013): 2578–82. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.2578.
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With the continual advancement of oil field development, water cut is an extremely important parameter which determines the transmission characteristics of the oil production and provides a scientific basis for oil and gas optimization exploration and increase of reservoir recovery. A new type of water cut meter based on fiber optic interferometer is proposed, sound pressure signal on the pipe is generated when the acoustic wave is propagated in a mixture of the pipe, the fiber optic sensors wrapped closely around the outside wall of pipe is capable of sensing sound pressure signal, the use of phase carrier technology aloud sound velocity is solved out through the method of Phase Generated Carrier (PGC) and sound pressure spectrum, then water cut can be solved according to the relationship between sound velocity and water cut.