Directional Response of a Horizontal Linear Array to an Acoustic Source at Close Range in Deep Water

A beamforming array technique with four sensors is applied to a cylindrical geometry for detecting point of impact. A linear array of acoustic sensors attached to the plate record the waveforms of Lamb waves generated at the impact point with individual time delay. A beamforming technique in conjunction with an optimization scheme that incorporates the direction dependent guided Lamb wave speed in cylindrical plates is developed. The optimization is carried out using the experimentally obtained wave speed as a function of propagation direction. The maximum value in the beamforming plot corresponds to the predicted point of impact. The proposed technique is experimentally verified by comparing the predicted points with the exact points of impact on a cylindrical aluminum plate and a cylindrical composite shell. For randomly chosen points of impact the beamforming technique successfully predicts the location of the acoustic source.

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Sensitivity Analysis of a Beamforming Technique for Acoustic Measurements

10.32920/ryerson.14661816.v1 ◽

2021 ◽

Author(s):

Pushpinder Singh Bhullar

Keyword(s):

Linear Array ◽

Sound Level ◽

Acoustic Measurements ◽

Acoustic Source ◽

Uniform Linear Array ◽

Random Array ◽

Planar Array ◽

Simulation Results ◽

Spiral Array ◽

Beamforming Technique

Beamforming is a technique that is used to determine the location of an acoustic source and the sound level spectrum of the signal produced by the source. This technique involves an array of microphones which record acoustic signals at multiple locations. A detailed analysis of the beamforming technique was carried out for three different array geometries: a uniform linear array, a uniform planar array, and a random array. The effect of various parameters, such as the number of microphones in an array, on the applicability of the technique was examined using both simulations and experiments. The simulation results established that the source localization capability of a uniform linear array is limited to an acoustic source lying in the plane of the array. In contrast, a planar array (either uniform or random) does not suffer the above limitation. The results also showed that a random array (eg., a spiral array) is the best of all the array geometries. The experimental results demonstrated the robustness of the beamforming technique in localizing an acoustic source and also confirmed the superiority of a uniform planar array over a uniform linear array.

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Impact of a Linear Array of Hydrophilic and Superhydrophobic Spheres on a Deep Water Pool

Colloids and Interfaces ◽

10.3390/colloids3010029 ◽

2019 ◽

Vol 3 (1) ◽

pp. 29

Author(s):

Guang Yang ◽

Visakh Vaikuntanathan ◽

Alexandros Terzis ◽

Xin Cheng ◽

Bernhard Weigand ◽

...

Keyword(s):

Deep Water ◽

High Speed ◽

Linear Array ◽

Leading Edge ◽

Water Pool ◽

Practical Applications ◽

Potential Control ◽

Wetting Properties ◽

Cavity Evolution ◽

The Impact

The impact of solid bodies on the free surface of liquid pools is involved in many practical applications—such as bullets and air-to-sea anti-torpedo defense systems, or the water entry of athletes in water sports—aimed at improving the performance through a control of cavity dynamics. This work reports an experimental investigation of the impact of a linear array of hydrophilic (H) and superhydrophobic (SH) spheres on a deep water pool. The array consisted of ten magnetic spheres, with different permutations of H and SH spheres. Using high speed shadowgraphy, we captured the underwater kinematics of the array for different permutations of H and SH spheres. In particular, we observed the evolution or absence of an air cavity attached to the array as a function of the position of the H and SH spheres. The position of the first SH sphere from the leading edge of the array (ZSH) emerged as a key parameter that alters the characteristics of cavity evolution. The appearance and pinch-off characteristics of a wake cavity behind the trailing edge were governed by the wetting properties of the leading and trailing surfaces of the array. The position of the first SH surface, as well as the wetting characteristics of the leading and trailing surfaces, are potential control parameters to alter underwater cavity evolution during solid surface impact on deep water pools.

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Sensitivity Analysis of a Beamforming Technique for Acoustic Measurements

10.32920/ryerson.14661816 ◽

2021 ◽

Author(s):

Pushpinder Singh Bhullar

Keyword(s):

Linear Array ◽

Sound Level ◽

Acoustic Measurements ◽

Acoustic Source ◽

Uniform Linear Array ◽

Random Array ◽

Planar Array ◽

Simulation Results ◽

Spiral Array ◽

Beamforming Technique

Beamforming is a technique that is used to determine the location of an acoustic source and the sound level spectrum of the signal produced by the source. This technique involves an array of microphones which record acoustic signals at multiple locations. A detailed analysis of the beamforming technique was carried out for three different array geometries: a uniform linear array, a uniform planar array, and a random array. The effect of various parameters, such as the number of microphones in an array, on the applicability of the technique was examined using both simulations and experiments. The simulation results established that the source localization capability of a uniform linear array is limited to an acoustic source lying in the plane of the array. In contrast, a planar array (either uniform or random) does not suffer the above limitation. The results also showed that a random array (eg., a spiral array) is the best of all the array geometries. The experimental results demonstrated the robustness of the beamforming technique in localizing an acoustic source and also confirmed the superiority of a uniform planar array over a uniform linear array.

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Unveiling a new deep water acoustic receiver and deep water acoustic source

10.4043/15076-ms ◽

2003 ◽

Author(s):

Stephen E. Spychalski

Keyword(s):

Deep Water ◽

Acoustic Source ◽

Acoustic Receiver

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Deep water towed array measurements at close range

The Journal of the Acoustical Society of America ◽

10.1121/1.4818869 ◽

2013 ◽

Vol 134 (4) ◽

pp. 3230-3241 ◽

Cited By ~ 8

Author(s):

Kevin D. Heaney ◽

Richard L. Campbell ◽

James J. Murray ◽

Arthur B. Baggeroer ◽

Eddie K. Scheer ◽

...

Keyword(s):

Deep Water ◽

Array Measurements ◽

Close Range ◽

Towed Array

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A novel T-shaped sensor cluster for acoustic source localization

Structural Health Monitoring ◽

10.1177/14759217211004236 ◽

2021 ◽

pp. 147592172110042

Author(s):

Qiang Gao ◽

Jun Young Jeon ◽

Gyuhae Park ◽

Yunde Shen ◽

Jiawei Xiang

Keyword(s):

Source Localization ◽

Linear Array ◽

Direction Of Arrival ◽

Small Region ◽

Superior Performance ◽

Maximum Deviation ◽

Acoustic Source ◽

Uniform Linear Array ◽

Blind Area ◽

Array Beamforming

This study proposes a new sensor cluster configuration for localizing an acoustic source in a plate using uniform linear array beamforming and T-shaped sensor clusters. This technique requires neither the properties of the plate material nor a dense array of sensors to find the direction of arrival of the acoustic source. It functions by placing four sensors in a cluster in the shape of the letter “‘T” over a small region of the plate. Uniform linear array beamforming-based source localization is carried out by the constructive interference of different sensor signals. However, this approach has the disadvantage of a very low resolution when the direction of arrival approaches certain values. The L-shaped sensor clusters use the information from the time difference of arrival between the sensors to estimate the direction of arrival, which has a high resolution in all directions except for the direction that is very close to vertical to the cluster. In this study, we numerically and experimentally demonstrate that the proposed T-shaped sensor cluster can accurately localize the acoustic source with no blind area. We also detail its superior performance compared to both uniform linear array beamforming and L-shaped clusters. In the experimental investigation, the maximum deviation of impact source localization was reduced significantly, from 54° to 4° for an aluminum plate, and from 42° to 3° for a composite plate. Furthermore, this novel combined sensor array layout requires only a few sensors, which can significantly reduce the cost of structural health monitoring practice.

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Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

Journal of Paleontology ◽

10.1017/s0022336000058819 ◽

1988 ◽

Vol 62 (01) ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Ronald E. Martin

Keyword(s):

Deep Water ◽

Benthic Foraminifera ◽

Carbonate Platform ◽

Sedimentary Facies ◽

Depositional Environments ◽

Near Surface ◽

Sediment Gravity Flows ◽

Gravity Flows ◽

Platform Margin ◽

Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

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Umatilla Virus Association with Fibrils and Tubules in Cultured Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600002063 ◽

1980 ◽

Vol 38 ◽

pp. 476-477

Author(s):

Neil M. Foster ◽

Ruth D. Breckon

Keyword(s):

Bluetongue Virus ◽

Linear Array ◽

Cultured Cells ◽

Intimate Association ◽

Infected Cells ◽

Dark Staining ◽

In Cells

Macrotubules have been described1 in cells infected with Umatilla virus (UMAV), an orbivirus for which bluetongue virus (BTV) is the protype. Macrotubules, often in linear array, were observed in the cytoplasm and in intimate association with viroplasms of infected cells. Macrotubules had outside and inside diameters of 20 and 15 nm and many had dark-staining centers with diameters similar to the interiors of the tubules. UMAV was 60 nm and the RNA core was 30 nm in diameter. This report describes the association of UMAV with macrotubules and two types of microtubules.

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