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Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The construction of acoustic-tamed marine ranching is of great significance to the proliferation of fishery resources,the protection of the marine environment,and the sustainable development of fishery. The study of the effective range of acoustic taming can provide a scientific and reasonable reference for the site selection of artificial reefs in marine ranching. In this study,the sound playing parameters for acoustic taming of Sebastes schlegelii were set concerning the T/ SCSF 0009—2021 technical regulations of fish acoustic taming in marine ranching. In the marine ranching demonstration area,300 Hz sine waves were played underwater to simulate the field acoustic taming. The underwater noise attenuation model was established through calculation. The results show that the horizontal attenuation formulas of 1 m,5 m,and 10 m underwater are:TTL =1. 73×10 logs(r); TTL =1. 58×10 log(r); TTL = 1. 70×10 log(r),and the underwater noise attenuation is spherical attenuation. In the marine ranching demonstration area,the effective radius of acoustic taming of the sine wave with the parameter of 300 Hz,155 dB for Sebastes schlegelii is 500 m,and the optimal radius of acoustic taming is 250 m. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the turbid underwater environment, due to the influence of multiple scattering and noise, the underwater imaging quality is greatly reduced. The existing significant target detection algorithms can't meet the task requirements of target detection accuracy. Therefore, this paper proposed an underwater salient target detection algorithm based on polarization imaging and salient region self-compensation. It divided the proposed algorithm into two stages. Firstly it used the method of estimating backscattered light based on polarization angle to remove the influence of backscattering, and introduced guided filter for underwater noise, and then removed the fuzzy effect caused by forward scattering through PSF function. Secondly it used an improved raster scanning algorithm combined with local feature descriptors to identify foreground superpixels, generated salient regions based on foreground superpixels to optimize and compensate the network, and then combined with DeepLabv3 + network to generate the final segmentation map. This paper conducted multiple sets of comparative experiments in a turbid underwater environment. The results show that the proposed restoration algorithm can effectively enhance the target, improve the contrast and clarity of the target, and the proposed salient target detection algorithm can accurately detect the underwater salient target and retain the detailed information. Combining the advantages of the polarization imaging model, this algorithm can better overcome the underwater complex optical imaging environment, and quickly and accurately detect significant underwater targets. [ABSTRACT FROM AUTHOR]

At present, the definition of sediment thickness is still in the empirical stage, and its mechanism research is not perfect. Therefore, this paper studies the characteristics of sediment at the bottom of underwater cast-in-place concrete pile with model test method, obtains the distribution characteristics of mud weight in pile hole, settlement rate of concrete block and interface morphology of sediment, and puts forward the mechanism of sediment formation by using theoretical analysis method. The results show that: (1) The gravity of the slurry in the pile hole increases with the increase of the depth, and the growth rate presents the characteristics of segmentation. (2) The settlement rate of the concrete mixture aggregates in the pile hole slurry can be divided into three stages: rapid increase, approximately constant increase and rapid decrease to stagnation. The settlement rate and final stagnation depth of the concrete simulation aggregates are positively related to the gravity, particle size and shape regularity. (3) The upper interface of the sediment is funnel-shaped, enabling the mixture to leave the pipe mouth and rush into the mud, which, in turn, push the mud around. (4) The formation mechanism of the sediment at the bottom of the cast-in-place pile is a comprehensive phenomenon, in which the multiphase fluid medium and plastic medium are closely related to the technology. The quasi hydrostatic analysis shows that whether the sediment is formed at the bottom of the underwater cast-in-place concrete pile is related to the pipe diameter, the material content of the hopper and the depth of pile hole. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of the difficulty in machining bionic groove surfaces of nickel-aluminum bronze alloy to improve its noise reduction performance, the bionic grooves were grinded on the surfaces of nickel-aluminum bronze alloy by pyramid bet and hollow spherical belt, and a test platform was set up to grind the surfaces of nickel-aluminum bronze alloy with bionic groove structure. The characteristics of grinding surfaces were extracted and the infinite element fluid noise analyses was carried out accordingly. The noise performance of pyramid abrasive belt grinding bionic surface and hollow ball abrasive belt grinding bionic groove surface was compared and analyzed. The results show that the average acoustic energy level of regular bionic groove surface grinded by pyramid abrasive belt is as 18.07 dB, and that of irregular bionic groove surface grinded by hollow ball abrasive belt is as 37.6 dB. In the experiments, the surfaces of nickel-aluminum bronze alloy grinded by two kinds of abrasive belt have bionic groove structure, and the regular bionic groove surfaces grinded by pyramid abrasive belt have better underwater noise reduction performance. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Image & Graphics is the property of Editorial Office of Journal of Image & Graphics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Underwater glider achieves floating and diving by changing its buoyancy, and realizes the forward gliding movement by virtue of hydrodynamic force. The use of underwater gliders for long-term, high concealment and large scale detection has become a current research focus. An underwater acoustic glider platform with target detection function was developed by integrating a single vector hydrophone in an existing underwater glider platform. The noises from vector hydrophone and underwater glider platform are test, and the self-noise level of vector hydrophone and the main noise source of underwater glider platform are analyzed. This study has significant guiding significance to reduce the vibration and noise and optimize the operating mode of acoustic system. The detection performance of underwater acoustic glider is analyzed from the experimental data collected in the experiment in the South China Sea in May 2018. The results show that the maximum detection distance of an underwater acoustic glider to detect a test surface vessel sailing at a speed 10 kn is longer than 14 km under good sea state in the deep sea. [ABSTRACT FROM AUTHOR]

Copyright of Hydrographic Surveying & Charting / Haiyang Cehui is the property of Hydrographic Surveying & Charting Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal on Communication / Tongxin Xuebao is the property of Journal on Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It is of great importance to acoustic stealth study of the vessel that the effectiveness of structure-borne sound design for the base is verified through large scale underwater model test. The composite low-noise base structure is summed up by the comprehensive uses of base link structures with high transmission loss, blocking mass as well as damping layer, and the preliminary application version is also given. Then underwater model test for large scale double shell is carried out, including vibration, sound radiation and input power flow test. The test data shows that the acceleration reductions of 20~1 000 Hz at base, tank wall and inner shell are more than 2 dB, and the input power flow of the structure is greatly attenuated. The 20~1000 Hz near field sound radiation pressure at 5 m has been reduced more than 5 dB. The circumferential distribution of 20~200 Hz sound pressure shows that sound pressures at low-middle frequencies are notably reduced by using composite low-noise base. [ABSTRACT FROM AUTHOR]