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A semantic segmentation-based underwater acoustic image transmission framework for cooperative SLAM

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Defence technology（防务技术） 2024年第3期33卷 339-351页

作者： Jiaxu Li Guangyao Han Shuai Chang Xiaomei Fu school of marine science and technology Tianjin UniversityTianjin 300072China

With the development of underwater sonar detection technology,simultaneous localization and mapping(SLAM)approach has attracted much attention in underwater navigation field in recent *** the weak detection ability of a single vehicle limits the SLAM performance in wide ***,cooperative SLAM using multiple vehicles has become an important research *** key factor of cooperative SLAM is timely and efficient sonar image transmission among underwater ***,the limited bandwidth of underwater acoustic channels contradicts a large amount of sonar image *** is essential to compress the images before ***,deep neural networks have great value in image compression by virtue of the powerful learning ability of neural networks,but the existing sonar image compression methods based on neural network usually focus on the pixel-level information without the semantic-level *** this paper,we propose a novel underwater acoustic transmission scheme called UAT-SSIC that includes semantic segmentation-based sonar image compression(SSIC)framework and the joint source-channel codec,to improve the accuracy of the semantic information of the reconstructed sonar image at the *** SSIC framework consists of Auto-Encoder structure-based sonar image compression network,which is measured by a semantic segmentation network's *** that sonar images have the characteristics of blurred target edges,the semantic segmentation network used a special dilated convolution neural network(DiCNN)to enhance segmentation accuracy by expanding the range of receptive *** joint source-channel codec with unequal error protection is proposed that adjusts the power level of the transmitted data,which deal with sonar image transmission error caused by the serious underwater acoustic *** results demonstrate that our method preserves more semantic information,with advantages over existing methods at the sa

关键词： Semantic segmentation Sonar image transmission Learning-based compression

Application of the finite analytic numerical method to a flowdependent variational data assimilation

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Acta Oceanologica Sinica 2024年第3期43卷 30-39页

作者： Yan Hu Wei Li Xuefeng Zhang Guimei Liu Liang Zhang Tianjin Key Laboratory for marine Environmental Research and Service School of Marine Science and TechnologyTianjin UniversityTianjin 300072China school of marine science and technology Tianjin UniversityTianjin 300072China National marine Environmental Forecasting Center Ministry of Natural ResourcesBeijing 100081China

An anisotropic diffusion filter can be used to model a flow-dependent background error covariance matrix,which can be achieved by solving the advection-diffusion *** of the directionality of the advection term,the discrete method needs to be chosen very *** finite analytic method is an alternative scheme to solve the advection-diffusion *** a combination of analytical and numerical methods,it not only has high calculation accuracy but also holds the characteristic of the auto *** demonstrate its ability,the one-dimensional steady and unsteady advection-diffusion equation numerical examples are respectively solved by the finite analytic *** more widely used upwind difference method is used as a control *** result indicates that the finite analytic method has higher accuracy than the upwind difference *** the two-dimensional case,the finite analytic method still has a better *** the three-dimensional variational assimilation experiment,the finite analytic method can effectively improve analysis field accuracy,and its effect is significantly better than the upwind difference and the central difference ***,it is still a more effective solution method in the strong flow region where the advective-diffusion filter performs most prominently.

关键词： finite analytic method advection-diffusion equation data assimilation flow-dependent

Performance of physical-informed neural network (PINN) for the key parameter inference in Langmuir turbulence parameterization scheme

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Acta Oceanologica Sinica 2024年第5期43卷 121-132页

作者： Fangrui Xiu Zengan Deng school of marine science and technology Tianjin UniversityTianjin 300072China

The Stokes production coefficient(E_(6))constitutes a critical parameter within the Mellor-Yamada type(MY-type)Langmuir turbulence(LT)parameterization schemes,significantly affecting the simulation of turbulent kinetic energy,turbulent length scale,and vertical diffusivity coefficient for turbulent kinetic energy in the upper ***,the accurate determination of its value remains a pressing scientific *** study adopted an innovative approach by leveraging deep learning technology to address this challenge of inferring the E_(6).Through the integration of the information of the turbulent length scale equation into a physical-informed neural network(PINN),we achieved an accurate and physically meaningful inference of E_(6).Multiple cases were examined to assess the feasibility of PINN in this task,revealing that under optimal settings,the average mean squared error of the E_(6) inference was only 0.01,attesting to the effectiveness of *** optimal hyperparameter combination was identified using the Tanh activation function,along with a spatiotemporal sampling interval of 1 s and 0.1 *** resulted in a substantial reduction in the average bias of the E_(6) inference,ranging from O(10^(1))to O(10^(2))times compared with other *** study underscores the potential application of PINN in intricate marine environments,offering a novel and efficient method for optimizing MY-type LT parameterization schemes.

关键词： Langmuir turbulence physical-informed neural network parameter inference

RMPC-Based Visual Servoing for Trajectory Tracking of Quadrotor UAVs With Visibility Constraints

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IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 2027-2029页

作者： Qifan Yang Huiping Li school of marine science and technology Northwestern Polytechnical UniversityXi’an 710072China

Dear Editor,This letter deals with the tracking problem of quadrotors subject to external disturbances and visibility constraints by designing a robust model predictive control(RMPC) scheme. According to the imagebase... 详细信息

关键词： Visual image visibility

Spatiotemporal Distributions of Bacterioplankton Communities in the Qiantang River(Hangzhou Section), China

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Journal of Ocean University of China 2024年第4期23卷 1102-1114页

作者： XU Jiaojiao ZHAO Li LUKWAMBE Betina NICHOLAUS Regan ZHU Jinyong YANG Wen ZHENG Zhongming school of marine sciences Ningbo University school of Aquatic sciences and Fisheries technology University of Dar es Salaam Department of Natural sciences Mbeya University of Science and Technology

The spatial and temporal distribution of bacterioplankton communities plays a vital role in understanding the ecological dynamics and health of aquatic *** this study,we conducted a comprehensive investigation of the bacterioplankton communities in the Qiantang River （Hangzhou section）.Water samples were collected quarterly from seven sites over a one-year *** and chemical parameters,including dissolved oxygen （DO）,water temperature （WT）,chemical oxygen demand （COD）,nitrite （NO2-）,active phosphate (PO43-) and other indices were *** this study,the α diversity,β diversity and abundance differences of bacterial communities were investigated using 16S rRNA high-throughput sequencing *** spatial and temporal distribution characteristics and main driving factors of the bacterioplankton community structure and diversity were *** results showed that a total of 57 phyla were detected in the bacterioplankton community,among which Proteobacteria and Actinomycetes were the two dominant groups with the highest relative *** results of PCoA based on Bray-Curtis distance showed that the sampling season had a slightly greater effect on the changes in bacterioplankton community structure in the Qiantang *** and partial Mantel test showed that environmental variables （Mantel r=0.6739,P<0.0001;partial Mantel r=0.507,P=0.0001） were more important than geographical distance （Mantel r=0.5322,P<0.001;partial Mantel r=0.1563,P=0.001）.The distance attenuation model showed that there was significant distance attenuation in all four seasons,and the maximum limit of bacterial community diffusion was found in *** analysis showed that nine environmental factors,including COD,WT and DO,significantly affected community distribution （P<0.05）.This study provides valuable insights into the spatial and temporal distribution characteristics of bacterioplankton communities,shedding light on their ecological roles in the Qiantang

关键词： Qiantang River bacterioplankton community spatial and temporal distribution 16S rRNA range attenuation

Characterization, Expression Pattern Analysis, and Cellular Localization of Two Homologous MUC2 Genes in Japanese Flounder(Paralichthys olivaceus)

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Journal of Ocean University of China 2024年第4期23卷 1035-1044页

作者： ZHU Ying YANG Xinsheng LI Zhengjie LI Chao school of marine science and Engineering Qingdao Agricultural University

As a member of mucins family, MUC2 is an important component of mucus, which is characterized by tandem and irregular repeat sequences rich in threonine and serine. It is strongly expressed by goblet cells that are involved in innate *** flounder is an economically important marine flatfish. In this study, two homologous genes of MUC2 were identified, named MUC2-1 and MUC2-2. Depending on phylogenetic and structural analysis, MUC2-1 and MUC2-2 were clustered in two clades, respectively. Paralichthys olivaceus MUC2-1 showed a closer relationship with MUC2 in the higher vertebrates. Various healthy tissues were analyzed to determine the expression patterns, and both MUC2 genes showed high expression levels in the gills and intestines. Following Edwardsiella tarda challenge, P. olivaceus MUC2-1 and MUC2-2 both showed significant up-regulated expression in intestine and kidney. Moreover, MUC2-1 was significantly up-regulated in gill cell lines following PGN and polyI:C stimulation,and MUC2-2 was significantly up-regulated in gill cell lines following LPS stimulation. In addition, ISH results revealed that MUC2-1 and MUC2-2 showed the same tissue localization in intestine tissues, but displayed different localization in gill. The siRNA-mediated knockdown of MUC2-1 and MUC2-2 genes in the gill cell lines of Japanese flounder affected the expressions of galnt family genes and smad pathway members that are related to mucosal immunity. The results provided a valuable insight into understanding the functions of MUC2 on mucosal immune system in response to the invasion of bacterial pathogen.

关键词： MUC2 ISH Edwardsiella tarda Paralichthys olivaceus

Turbulence Statistics of Thermo-Buoyancy Supercritical Fuel Flow in a Regenerative Cooling Channel

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Journal of Thermal science 2024年第1期33卷 126-137页

作者： SUN Feng XIE Gongnan school of marine science and technology Northwestern Polytechnical UniversityXi'an 710072China Department of Thermal Engineering Tsinghua UniversityBeijing 100084China

Active regenerative cooling with supercritical hydrocarbon fuel is considered as the most promising thermal protection *** existence of buoyancy force would lead to strongly anisotropic flow and thermal transport *** is closely related to the cooling performance of the *** elucidate the mechanisms of turbulent transport,the large eddy simulation(LES) was performed to assess turbulence statistics within different turbulence *** results indicated that the buoyancy and inertial force together dominated the change of turbulent ***,the spatial thermal buoyancy effect significantly suppressed the vertical velocity *** is due to the laminar motion caused by the buoyancy force,thereby weakening the thermal *** the statistics of velocity fluctuation,it was found that the buoyancy force and inertial force greatly weaken the vertical and streamwise velocity fluctuation,*** the statistics of thermal transport,the results pointed out that the near-wall heat transport characteristics need to be paid more *** thickness of the temperature mixing boundary layer led to the attenuation of vertical heat flux,which inhibited vertical temperature diffusion and predisposed to extreme conditions of heat transfer *** results can enhance the academic understanding of the heat transfer mechanism of supercritical fluids,and give guidance for further applications of thermal protection.

关键词： active regenerative cooling large eddy simulation(LES) buoyancy force turbulence statistics

Neural network study of the nuclear ground-state spin distribution within a random interaction ensemble

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Nuclear science and Techniques 2024年第3期35卷 216-227页

作者： Deng Liu Alam Noor A Zhen-Zhen Qin Yang Lei school of Mathematics and Physics Southwest University of Science and TechnologyMianyang 621010China school of Nuclear science and technology Southwest University of Science and TechnologyMianyang 621010China

The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and the corresponding ground-state spins as labels or output *** quantum many-body system problem exceeds the capability of our optimized NNs in terms of accurately predicting the ground-state spin of each sample within the ***,our NN model effectively captured the statistical properties of the ground-state spin because it learned the empirical regularity of the ground-state spin distribution in TBRE,as discovered by physicists.

关键词： Neural network Two-body random ensemble Spin distribution of nuclear ground state

Combined effects of massive reclamation and dredging on the variations in hydrodynamic and sediment transport in Lingdingyang Estuary,China

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高等学校学术文摘·地球科学前沿 2024年第1期18卷 127-147页

作者： Kanglin CHEN Yitong LIN Jing LIU Zixiao HE Liangwen JIA school of Geography and Remote Sensing Guangzhou UniversityGuangzhou 510006China school of marine science Sun Yat-Sen UniversityGuangzhou 510275China school of marine Engineering and technology Sun Yat-Sen UniversityGuangzhou 510275China Southern marine science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519080China school of marine Engineering and technology Sun Yat-Sen UniversityGuangzhou 510275China Southern marine science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519080China Guangdong Province Engineering Research Center of Coasts Islands and ReefsGuangzhou 510275China

Anthropogenic disturbances associated with the rapid development of coastal cities have drastically influenced the hydrodynamics and sediment transport processes in many large estuaries *** Estuary(LE),located in the central and southern part of the Pearl River Delta,southern China with a long history of high-intensity anthropogenic disturbances,was studied to explore the contribution rate and mechanism underlying the alteration in hydrodynamics and sediment transport under each phase of human activity.A state-of-the-art modeling tool(TELEMAC-2D),was used to study the variations in the hydrodynamics and sediment transport,accounting for reclamation-induced shoreline and dredging-induced topography *** results indicated that:ⅰ)under the influence of successive land reclamation,the general distribution of the Confluence Hydrodynamic Zone(CHZ)in LE varied from scattered to concentrated,and these zones moved 3-5 km seaward.ⅱ)Large-scale channel dredging weakened the residual flow in LE,decreasing the residual flow in the Inner-Lingding Estuary(ILE)by 62.45％.This was initiated by the enhancement of tidal dynamics through changes in the bottom friction caused by dredging in the *** contrast,massive reclamation decreased the residual flow in the ILE by 17.55％and increased that in the Outer-Lingding Estuary(OLE).ⅲ)Despite disturbances related to land reclamation and dredging,the estuarine jet flow in LE remained a turbulent jet system,and the estuarine jet flow became more *** addition,the position of the estuarine jet source moved 6-13 km seaward.ⅳ)Both reclamation and dredging decreased the SSC in the ILE and increased the SSC in the *** weakened the SSC in the ILE by 62.19％,whereas dredging enhanced the SSC in the OLE by 49％.Spatially,reclamation resulted in an increase in the SSC near the outlets and a decrease in the SSC in the northern portion of the Western *** mainly increased the SSC in the northern

关键词： reclamation and dredging estuarine jet flow dynamics and sediment transport mechanism Lingdingyang Estuary