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Effect of stratification on current hydrodynamics over Louisiana shelf during Hurricane Katrina

Water Science and Engineering 2017年第2期10卷 154-165页

作者： Mohammad Nabi Allahdadi Chunyan Li Department of oceanography and Coastal Sciences College of the Coast and Environment Louisiana State University Baton Rouge 70803 USA

Numerical experiments were conducted using the finite volume community ocean model(FVCOM) to study the impact of the initial density stratification on simulated currents over the Louisiana shelf during Hurricane Katrina. Model results for two simulation scenarios, including an initially stratified shelf and an initially non-stratified shelf, were examined. Comparison of two simulations for two-dimensional(2D) currents,the time series of current speed, and variations of cross-shore currents across different sections showed that the smallest differences between simulated currents for these two scenarios occurred over highly mixed regions within 1 radius of maximum wind(RMW) under the *** areas farther from the mixed zone, differences increased, reaching the maximum values off Terrebonne Bay. These large discrepancies correspond to significant differences between calculated vertical eddy viscosities for the two scenarios. The differences were addressed based on the contradictory behavior of turbulence in a stratified fluid, as compared to a non-stratified fluid. Incorporation of this behavior in the MellorYamada turbulent closure model established a Richardson number-based stability function that was used for estimation of the vertical eddy viscosity from the turbulent energy and macroscale. The results of this study demonstrate the necessity for inclusion of shelf stratification when circulation modeling is conducted using three-dimensional(3D) baroclinic models. To achieve high-accuracy currents, the parameters associated with the turbulence closures should be calibrated with field measurements of currents at different depths.

关键词： Hurricane Katrina Louisiana shelf Hydrodynamics Baroclinic and barotropic models Stratification

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Robust template feature matching method using motion-constrained DCF designed for visual navigation in asteroid landing

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Astrodynamics 2023年第1期7卷 83-99页

作者： Yaqiong Wang Xiongfeng Yan Zhen Ye Huan Xie Shijie Liu Xiong Xu Xiaohua Tong college of Surveying and Geo-informatics and Shanghai Key Laboratory of Space Mapping and Remote Sensing for Planetary EaplorationTongji UniversityShanghai 200092China Shanghai Institute of Intelligent Science and Technology Shanghai 200092China

A robust and eficient feature matching method is necessary for visual navigation in asteroid-landing *** on the visual navigation framework and motion characteristics of asteroids,a robust and efficient template feature matching method is proposed to adapt to feature distortion and scale change cases for visual navigation of *** proposed method is primarily based on a motion-constrained discriminative correlation filter(DCF).The prior information provided by the motion constraints between sequence images is used to provide a predicted search region for template feature ***,some specific template feature samples are generated using the motion constraints for correlation filter learning,which is beneficial for training a scale and feature distortion adaptive correlation filter for accurate feature ***,average peak-to-correlation energy(APCE)and jointly consistent measurements(JCMs)were used to eliminate false *** captured by the Touch And Go Camera System(TAGCAMS)of the Bennu asteroid were used to evaluate the performance of the proposed *** particular,both the robustness and accuracy of region matching and template center matching are *** qualitative and quantitative results illustrate the advancement of the proposed method in adapting to feature distortions and large-scale changes during spacecraft landing.

关键词： discriminative correlation filter(DCF) motion constraints feature distortion adaptive scale changes adaptive template feature matching

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Abnormal Action Detection Based on Parameter-Efficient Transfer Learning in Laboratory Scenarios

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Computers, Materials & Continua 2024年第9期80卷 4219-4242页

作者： Changyu Liu Hao Huang Guogang Huang Chunyin Wu Yingqi Liang college of Mathematics and informatics South China Agricultural UniversityGuangzhou510642China School of oceanography Shanwei Institute of TechnologyShanwei516600China Technical Department Kerric(Guangdong)Laboratory Equipment Research and Manufacture Co.Ltd.Foshan528139China

Laboratory safety is a critical area of broad societal concern,particularly in the detection of abnormal *** enhance the efficiency and accuracy of detecting such actions,this paper introduces a novel method called TubeRAPT(Tubelet Transformer based onAdapter and Prefix TrainingModule).Thismethod primarily comprises three key components:the TubeR network,an adaptive clustering attention mechanism,and a prefix training *** components work in synergy to address the challenge of knowledge preservation in models pretrained on large datasets while maintaining training *** TubeR network serves as the backbone for spatio-temporal feature extraction,while the adaptive clustering attention mechanism refines the focus on relevant *** prefix training module facilitates efficient fine-tuning and knowledge *** results demonstrate the effectiveness of TubeRAPT,achieving a 68.44%mean Average Precision(mAP)on the CLA(Crazy LabActivity)small-scale dataset,marking a significant improvement of 1.53%over the previous TubeR *** research not only showcases the potential applications of TubeRAPT in the field of abnormal action detection but also offers innovative ideas and technical support for the future development of laboratory safety monitoring *** proposed method has implications for improving safety management systems in various laboratory environments,potentially reducing accidents and enhancing overall workplace safety.

关键词： Parameter-efficient transfer learning laboratory scenarios TubeRAPT abnormal action detection

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A wave energy resource assessment in the China's seas based on multi-satellite merged radar altimeter data

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Acta Oceanologica Sinica 2015年第3期34卷 115-124页

作者： WAN Yong ZHANG Jie MENG Junmin WANG Jing college of Information Science and Engineering Ocean University of China First Institute of oceanography State Oceanic Administration college of Information and Control Engineering China University of Petroleum

Wave energy resources are abundant in both offshore and nearshore areas of the China＇s seas. A reliable assessment of the wave energy resources must be performed before they can be exploited. First, for a water depth in offshore waters of China, a parameterized wave power density model that considers the effects of the water depth is introduced to improve the calculating accuracy of the wave power density. Second, wave heights and wind speeds on the surface of the China＇s seas are retrieved from an AVISO multi-satellite altim-eter data set for the period from 2009 to 2013. Three mean wave period inversion models are developed and used to calculate the wave energy period. Third, a practical application value for developing the wave energy is analyzed based on buoy data. Finally, the wave power density is then calculated using the wave field data. Using the distribution of wave power density, the energy level frequency, the time variability indexes, the to-tal wave energy and the distribution of total wave energy density according to a wave state, the offshore wave energy in the China＇s seas is assessed. The results show that the areas of abundant and stable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait, southeast of Taiwan in the China＇s seas; the wave power density values in these areas are approximately 14.0–18.5 kW/m. The wave energy in the China’s seas presents obvious seasonal variations and optimal seasons for a wave energy utilization are in winter and autumn. Except for very coastal waters, in other sea areas in the China＇s seas, the energy is primarily from the wave state with 0.5 m≤Hs≤4 m, 4 s≤Te≤10 s whereHs is a significant wave height andTe is an energy period; within this wave state, the wave energy accounts for 80% above of the total wave energy. This characteristic is advantageous to designing wave energy convertors （WECs）. The practical application value of the wave energy is higher which can be

关键词： China's seasmulti-satellite merged altimeter data wave energy resources assessment wave power density

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Exploitable wave energy assessment based on ERA-Interim reanalysis data—A case study in the East China Sea and the South China Sea

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Acta Oceanologica Sinica 2015年第9期34卷 143-155页

Wave energy resources assessment is a very important process before the exploitation and utilization of the wave energy. At present, the existing wave energy assessment is focused on theoretical wave energy conditions for interesting areas. While the evaluation for exploitable wave energy conditions is scarcely ever performed. Generally speaking, the wave energy are non-exploitable under a high sea state and a lower sea state which must be ignored when assessing wave energy. Aiming at this situation, a case study of the East China Sea and the South China Sea is performed. First, a division basis between the theoretical wave energy and the exploitable wave energy is studied. Next, based on recent 20 a ERA-Interim wave field data, some indexes including the spatial and temporal distribution of wave power density, a wave energy exploitable ratio, a wave energy level, a wave energy stability, a total wave energy density, the seasonal variation of the total wave energy and a high sea condition frequency are calculated. And then the theoretical wave energy and the exploitable wave energy are compared each other; the distributions of the exploitable wave energy are assessed and a regional division for exploitable wave energy resources is carried out; the influence of the high sea state is evaluated. The results show that considering collapsing force of the high sea state and the utilization efficiency for wave energy, it is determined that the energy by wave with a significant wave height being not less 1 m or not greater than 4 m is the exploitable wave energy. Compared with the theoretical wave energy, the average wave power density, energy level, total wave energy density and total wave energy of the exploitable wave energy decrease obviously and the stability enhances somewhat. Pronounced differences between the theoretical wave energy and the exploitable wave energy are present. In the East China Sea and the South China Sea, the areas of an abundant and stable exploit

关键词： wave energy assessment ERA-Interim reanalysis data exploitable wave energy theoretical waveenergy wave power density high sea state

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Limited Sea Surface Temperature Cooling Due to the Barrier Layer Promoting Super Typhoon Mangkhut(2018)

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Advances in Atmospheric Sciences 2024年第11期41卷 2156-2172页

作者： Huipeng WANG Jiagen LI Junqiang SONG Liang SUN Fu LIU Han ZHANG Kaijun REN Huizan WANG Chunming WANG Jinrong ZHANG Hongze LENG college of Meteorology and oceanography National University of Defense TechnologyChangsha 410073China School of Earth and space Sciences University of Science and Technology of ChinaHefei 230000China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China

This study investigates the impact of the salinity barrier layer(BL)on the upper ocean response to Super Typhoon Mangkhut(2018)in the western North *** the passage of Mangkhut,a noticeable increase(~0.6 psu)in sea surface salinity and a weak decrease(<1℃)in sea surface temperature(SST)were observed on the right side of the typhoon ***-induced SST change can be divided into the three stages,corresponding to the variations in BL thickness and SST before,during,and after the passage of *** the pre-typhoon stage,SST slightly warmed due to the entrainment of BL warm water,which suppressed the cooling induced by surface heat fluxes and horizontal *** the forced stage,SST cooling was controlled by entrainment,and the preexisting BL reduced the total cooling by 0.89℃ d-1,thus significantly weakening the overall SST cooling induced by *** the relaxation stage,the SST cooling was primarily caused by the *** results indicate that a preexisting BL can limit typhoon-induced SST cooling by suppressing the entrainment of cold thermocline water,which contributed to Mangkhut becoming the strongest typhoon in 2018.

关键词： sea surface cooling mixed-layer depth barrier layer typhoon

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spacelike Mobius Hypersurfaces in Four Dimensional Lorentzian space Form

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Acta Mathematica Sinica,English Series 2019年第4期35卷 519-536页

作者： Yan Bin LIN Ying Lü Chang Ping WANG college of Mathematics and informatics Fujian Normal University School of Mathematical Sciences Xiamen University

In this paper, we first set up an alternative fundamental theory of M?bius geometry for any umbilic-free spacelike hypersurfaces in four dimensional Lorentzian space form, and prove the hypersurfaces can be determined completely by a system consisting of a function W and a tangent frame {E_i}. Then we give a complete classification for spacelike M?bius homogeneous hypersurfaces in four dimensional Lorentzian space form. They are either M?bius equivalent to spacelike Dupin hypersurfaces or to some cylinders constructed from logarithmic curves and hyperbolic logarithmic spirals. Some of them have parallel para-Blaschke tensors with non-vanishing M?bius form.

关键词： Mobius form Mobius metric para-Blaschke tensor Mobius homogeneous hypersurface hyperbolic logarithmic spiral Dupin hypersurface

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Validation of the multi-satellite merged sea surface salinity in the South China Sea

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Journal of Oceanology and Limnology 2023年第6期41卷 2033-2044页

作者： Huipeng WANG Junqiang SONG Chengwu ZHAO Xiangrong YANG Hongze LENG Nan ZHOU college of Meteorology and oceanography National University of Defense TechnologyChangsha 410073China Troop 61741 PLABeijing 100094China

Sea surface salinity(SSS)is an essential variable of ocean dynamics and climate *** Soil Moisture and Ocean Salinity(SMOS),Aquarius,and Soil Moisture Active Passive(SMAP)satellite missions all provide SSS *** European space Agency(ESA)Climate Change Initiative Sea Surface Salinity(CCI-SSS)project merged these three satellite SSS data to produce CCI L4SSS *** validated the accuracy of the four satellite products(CCI,SMOS,Aquarius,and SMAP)using in-situ gridded data and Argo floats in the South China Sea(SCS).Compared with in-situ gridded data,it shows that the CCI achieved the best performance(RMSD:0.365)on monthly time *** RMSD of SMOS,Aquarius,and SMAP(SMOS:0.389;Aquarius:0.409;SMAP:0.391)are close,and the SMOS takes a slight advantage in contrast with Aquarius and *** discrepancies can be found near the coastline and in the shelf ***,CCI with lower RMSD(0.295)perform better than single satellite data(SMOS:0.517;SMAP:0.297)on weekly time scales compared with Argo ***,the merged CCI have the smallest RMSD among the four satellite products in the SCS on both weekly time scales and monthly time scales,which illustrates the improved accuracy of merged CCI compared with the individual satellite data.

关键词： sea surface salinity(SSS) South China Sea(SCS) Argo multi-satellite merged data validation

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Detection of oil spill based on CBF-CNN using HY-1C CZI multispectral images

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Acta Oceanologica Sinica 2022年第7期41卷 166-179页

作者： Kai Du Yi Ma Zongchen Jiang Xiaoqing Lu Junfang Yang college of Geodesy and Geomatics Shandong University of Science and TechnologyQingdao266590China First Institute of Oceanology Ministry of Natural ResourcesQingdao266061China School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin150001China National Satellite Ocean Application Service Beijing100081China college of oceanography and space informatics China University of Petroleum(East China)Qingdao266580China Technology Innovation Center for Ocean Telemetry Ministry of Natural ResourcesQingdao266061China National Engineering Laboratory for Integrated Aero-space-Ground-Ocean Big Data Application Technology Xi’an710072China

Accurate detection of an oil spill is of great significance for rapid response to oil spill *** images have the advantages of high spatial resolution,short revisit period,and wide imaging width,which is suitable for large-scale oil spill ***,in wide remote sensing images,the number of oil spill samples is generally far less than that of seawater ***,the sea surface state tends to be heterogeneous over a large area,which makes the identification of oil spills more difficult because of various sea conditions and *** address this problem,we used the F-Score as a measure of the distance between forecast value and true value,proposed the Class-Balanced F loss function(CBF loss function)that comprehensively considers the precision and recall,and rebalances the loss according to the actual sample numbers of various *** the CBF loss function,we constructed convolution neural networks(CBF-CNN)for oil spill *** on the image acquired by the Coastal Zone Imager(CZI)of the Haiyang-1C(HY-1C)satellite in the Andaman Sea(study area 1),we carried out parameter adjustment *** contrast to experiments of different loss functions,the F1-Score of the detection result of oil emulsions is 0.87,which is 0.03–0.07 higher than cross-entropy,hinge,and focal loss functions,and the F1-Score of the detection result of oil slicks is 0.94,which is 0.01–0.09 higher than those three loss *** comparison with the experiment of different methods,the F1-Score of CBF-CNN for the detection result of oil emulsions is 0.05–0.12 higher than that of the deep neural networks,supports vector machine and random forests models,and the F1-Score of the detection result of oil slicks is 0.15–0.22 higher than that of the three *** verify the applicability of the CBF-CNN model in different observation scenes,we used the image obtained by HY-1C CZI in the Karimata Strait to carry out experiments,which include two stu

关键词： oil spills CNN classification loss function sunglint detection

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Positional Error Model of Line Segments with Modeling and Measuring Errors Using Brownian Bridge

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Journal of Geodesy and Geoinformation Science 2023年第2期6卷 1-10页

作者： Xiaohua TONG Lejingyi ZHOU Yanmin JIN college of Surveying and Geo-informatics Tongji UniversityShanghai 200092China Shanghai Key Laboratory for Planetary Mapping and Remote Sensing for Deep space Exploration Shanghai 200092China

Spatial linear features are often represented as a series of line segments joined by measured endpoints in surveying and geographic information *** are not only the measuring errors of the endpoints but also the modeling errors between the line segments and the actual geographical *** paper presents a Brownian bridge error model for line segments combining both the modeling and measuring ***,the Brownian bridge is used to establish the position distribution of the actual geographic feature represented by the line ***,an error propagation model with the constraints of the measuring error distribution of the endpoints is ***,a comprehensive error band of the line segment is constructed,wherein both the modeling and measuring errors are *** proposed error model can be used to evaluate line segments’overall accuracy and trustability influenced by modeling and measuring errors,and provides a comprehensive quality indicator for the geospatial data.

关键词： spatial data line segment modeling error measuring error Brownian bridge

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