The problem of wave scattering by undulating bed topography in a two-layer ocean is investigated on the basis of linear theory. In a two-layer fluid with the upper layer having a free surface, there exist two modes of...The problem of wave scattering by undulating bed topography in a two-layer ocean is investigated on the basis of linear theory. In a two-layer fluid with the upper layer having a free surface, there exist two modes of waves propagating at both the free surface of the upper layer and the interface between the two layers. Due to a wave train of a particular mode incident on an obstacle which is bottom-standing on the lower layer, reflected and transmitted waves of both modes are created by the obstacle. For small undulations on the bottom of the lower layer, a perturbation method is employed to obtain first-order reflection and transmission coefficients of both modes for incident wave trains of again both modes in terms of integrals involving the bed-shape fimction. For sinusoidal undulations, numerical results are presented graphically to illustrate the energy transfer between the waves of different modes by the undulating bed.展开更多
A weak nonlinear model of a two-layer barotropic ocean with Rayleigh dissipation is built.The analytic asymptotic solution is derived in the mid-latitude stationary wind field,and the physical meaning of the correspon...A weak nonlinear model of a two-layer barotropic ocean with Rayleigh dissipation is built.The analytic asymptotic solution is derived in the mid-latitude stationary wind field,and the physical meaning of the corresponding problem is discussed.展开更多
Open caissons are widely used in foundation engineering because of their load-bearing efficiency and adaptability in diverse soil conditions.However,accurately predicting their undrained bearing capacity in layered so...Open caissons are widely used in foundation engineering because of their load-bearing efficiency and adaptability in diverse soil conditions.However,accurately predicting their undrained bearing capacity in layered soils remains a complex challenge.This study presents a novel application of five ensemble machine(ML)algorithms-random forest(RF),gradient boosting machine(GBM),extreme gradient boosting(XGBoost),adaptive boosting(AdaBoost),and categorical boosting(CatBoost)-to predict the undrained bearing capacity factor(Nc)of circular open caissons embedded in two-layered clay on the basis of results from finite element limit analysis(FELA).The input dataset consists of 1188 numerical simulations using the Tresca failure criterion,varying in geometrical and soil parameters.The FELA was performed via OptumG2 software with adaptive meshing techniques and verified against existing benchmark studies.The ML models were trained on 70% of the dataset and tested on the remaining 30%.Their performance was evaluated using six statistical metrics:coefficient of determination(R²),mean absolute error(MAE),root mean squared error(RMSE),index of scatter(IOS),RMSE-to-standard deviation ratio(RSR),and variance explained factor(VAF).The results indicate that all the models achieved high accuracy,with R²values exceeding 97.6%and RMSE values below 0.02.Among them,AdaBoost and CatBoost consistently outperformed the other methods across both the training and testing datasets,demonstrating superior generalizability and robustness.The proposed ML framework offers an efficient,accurate,and data-driven alternative to traditional methods for estimating caisson capacity in stratified soils.This approach can aid in reducing computational costs while improving reliability in the early stages of foundation design.展开更多
This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerge...This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerged cylindrical buoy.The system is modeled as a two-layer fluid with infinite horizontal extent and finite depth.The radiation problem is analyzed in the context of linear water waves.The fluid domain is divided into outer and inner zones,and mathematical solutions for the pitch radiating potential are derived for the corresponding boundary valve problem in these zones using the separation of variables approach.Using the matching eigenfunction expansion method,the unknown coefficients in the analytical expression of the radiation potentials are evaluated.The resulting radiation potential is then used to compute the added mass and damping coefficients.Several numerical results for the added mass and damping coefficients are investigated for numerous parameters,particularly the effects of the cylinder radius,the draft of the submerged cylinder,and the density proportion between the two fluid layers across different frequency ranges.The major findings are presented and discussed.展开更多
A two-layer primitive equation model is developed in this paper. The capabilities of this model aretested by the use of multiyearly averaged January and July sea surface level pressure fields and windfields which can ...A two-layer primitive equation model is developed in this paper. The capabilities of this model aretested by the use of multiyearly averaged January and July sea surface level pressure fields and windfields which can be diagnosed from the pressure fields. The results show that the ocean surface currentsand undercurrents in the second layer driven by the sea surface wind and the sea surface pressure areclose to the observation. The results are also compared with that of the IAP OGCM and the OSUOGCM.展开更多
Network Intrusion Detection System(NIDS)detection of minority class attacks is always a difficult task when dealing with attacks in complex network environments.To improve the detection capability of minority-class at...Network Intrusion Detection System(NIDS)detection of minority class attacks is always a difficult task when dealing with attacks in complex network environments.To improve the detection capability of minority-class attacks,this study proposes an intrusion detection method based on a two-layer structure.The first layer employs a CNN-BiLSTM model incorporating an attention mechanism to classify network traffic into normal traffic,majority class attacks,and merged minority class attacks.The second layer further segments the minority class attacks through Stacking ensemble learning.The datasets are selected from the generic network dataset CIC-IDS2017,NSL-KDD,and the industrial network dataset Mississippi Gas Pipeline dataset to enhance the generalization and practical applicability of the model.Experimental results show that the proposed model achieves an overall detection accuracy of 99%,99%,and 95%on the CIC-IDS2017,NSL-KDD,and industrial network datasets,respectively.It also significantly outperforms traditional methods in terms of detection accuracy and recall rate for minority class attacks.Compared with the single-layer deep learning model,the two-layer structure effectively reduces the false alarm rate while improving the minority-class attack detection performance.The research in this paper not only improves the adaptability of NIDS to complex network environments but also provides a new solution for minority-class attack detection in industrial network security.展开更多
BACKGROUND The early diagnosis rate of pancreatic ductal adenocarcinoma(PDAC)is low and the prognosis is poor.It is important to develop an interpretable noninvasive early diagnostic model in clinical practice.AIM To ...BACKGROUND The early diagnosis rate of pancreatic ductal adenocarcinoma(PDAC)is low and the prognosis is poor.It is important to develop an interpretable noninvasive early diagnostic model in clinical practice.AIM To develop an interpretable noninvasive early diagnostic model for PDAC using plasma extracellular vesicle long RNA(EvlRNA).METHODS The diagnostic model was constructed based on plasma EvlRNA data.During the process of establishing the model,EvlRNA-index was introduced,and four algorithms were adopted to calculate EvlRNA-index.After the model was successfully constructed,performance evaluation was conducted.A series of bioinformatics methods were adopted to explore the potential mechanism of EvlRNA-index as the input feature of the model.And the relationship between key characteristics and PDAC were explored at the single-cell level.RESULTS A novel interpretable machine learning framework was developed based on plasma EvlRNA.In this framework,a two-layer classifier was established.A new concept was proposed:EvlRNA-index.Based on EvlRNA-index,a cancer diagnostic model was established,and a good diagnostic effect was achieved.The accuracy of PDACandCPvsHealth-Probabilistic PCA Index-SVM(PDAC and chronic pancreatitis vs health-probabilistic principal component analysis index-support vector machine)(1-18)was 91.51%,with Mathew’s correlation coefficient 0.7760 and area under the curve 0.9560.In the second layer of the model,the accuracy of PDACvsCP-Probabilistic PCA Index-RF(PDAC vs chronic pancreatitis-probabilistic principal component analysis index-random forest)(2-17)was 93.83%,with Mathew’s correlation coefficient 0.8422 and area under the curve 0.9698.Forty-nine PDAC-related genes were identified,among which 16 were known,inferring that the remaining ones were also PDAC-related genes.CONCLUSION An interpretable two-layer machine learning framework was proposed for early diagnosis and prediction of PDAC based on plasma EvlRNA,providing new insights into the clinical value of EvlRNA.展开更多
In the wake of major natural disasters or human-made disasters,the communication infrastruc-ture within disaster-stricken areas is frequently dam-aged.Unmanned aerial vehicles(UAVs),thanks to their merits such as rapi...In the wake of major natural disasters or human-made disasters,the communication infrastruc-ture within disaster-stricken areas is frequently dam-aged.Unmanned aerial vehicles(UAVs),thanks to their merits such as rapid deployment and high mobil-ity,are commonly regarded as an ideal option for con-structing temporary communication networks.Con-sidering the limited computing capability and battery power of UAVs,this paper proposes a two-layer UAV cooperative computing offloading strategy for emer-gency disaster relief scenarios.The multi-agent twin delayed deep deterministic policy gradient(MATD3)algorithm integrated with prioritized experience replay(PER)is utilized to jointly optimize the scheduling strategies of UAVs,task offloading ratios,and their mobility,aiming to diminish the energy consumption and delay of the system to the minimum.In order to address the aforementioned non-convex optimiza-tion issue,a Markov decision process(MDP)has been established.The results of simulation experiments demonstrate that,compared with the other four base-line algorithms,the algorithm introduced in this paper exhibits better convergence performance,verifying its feasibility and efficacy.展开更多
Ocean geoscience is a highly integrated and interdisciplinary field that plays a critical role in understanding the interaction between Earth’s lithosphere,hydrosphere,atmosphere,biosphere,and anthroposphere.Recent y...Ocean geoscience is a highly integrated and interdisciplinary field that plays a critical role in understanding the interaction between Earth’s lithosphere,hydrosphere,atmosphere,biosphere,and anthroposphere.Recent years have seen tremendous progress in global ocean research,driven by rapid advancements in deep-sea manned and unmanned submersibles,ocean drilling,seafloor observatories,big data assimilation,and supercomputing simulations.Representative examples of breakthroughs are highlighted in this work:(1)Probing sub-seafloor processes.A 10,000-meter ocean-bottom seismometer array has achieved high-resolution imaging of the deepest ocean on the Earth-the Challenger Deep of the Mariana Trench,revealing the role of key tectonic and hydrological processes within the subduction zone.The first sub-ice seafloor seismic and magnetotelluric experiments were successfully conducted at the Arctic Gakkel Ridge,providing significant insights into the dynamics of ultraslow seafloor spreading.(2)Exploration of seafloor resources.Near-seafloor investigations employing underwater robotics and multi-sensor systems have been carried out in areas of hydrothermal vents and cold seeps at global locations,including the Southwest Indian Ridge.These efforts have combined geophysical,oceanographic,chemical,and biological observations with extensive seafloor sampling.(3)Interdisciplinary research of complex catastrophic events.High-resolution simulations integrating ocean observations with supercomputing modeling have made it possible to fully model earthquake-induced seafloor deformation,tsunami propagation,and ocean basin-scale transport of the Fukushima Power Plant-derived radionuclides associated with the 2011 Tohoku earthquake.Among the world’s three major oceans,the Indian Ocean is still relatively underexplored.Major scientific challenges include elucidating crust-mantle interaction,air-sea dynamic coupling,large-scale marine hazards,and responses of ecosystems to major environmental changes,all of which require interdisciplinary collaboration.Future efforts should focus on developing intelligent unmanned observation platform systems,big data and digital twins,and AI-driven hazard modeling.Meanwhile,higher educational reforms should emphasize fostering a new generation of students and young scientists with a solid background and strong critical analysis skills to accelerate technological innovation.展开更多
On July 2^(nd),2025,32 scientists representing 15 countries gathered at Tartu,Estonia to make on-site endorsements for the Global ONCE(Ocean Negative Carbon Emissions)Program at the 12th INTECOL Wetlands Conference.Th...On July 2^(nd),2025,32 scientists representing 15 countries gathered at Tartu,Estonia to make on-site endorsements for the Global ONCE(Ocean Negative Carbon Emissions)Program at the 12th INTECOL Wetlands Conference.This marks a significant milestone for ONCE in establishing a systematic framework for coastal wetland carbon sequestration research and global collaboration(Figs.1,2).Coastal wetlands are critical transition zones linking terrestrial and marine ecosystems,yet they face severe degradation from anthropogenic land-based activities and sea level rise that propagate impacts to the ocean.As a UN Ocean Decade Program,the Global ONCE Program champions interdisciplinary and cross-regional collaboration to enhance carbon sequestration in the ocean and coastal wetlands through science and innovation.Aligned with the Tartu Declaration on Wetlands that includes resolutions to promote the rights of global wetlands(especially peatlands)and advance the discipline of wetland science based on facts,this initiative addresses key knowledge gaps in land-ocean interactions.The goal is to harness the full potential of coastal wetlands and ocean systems for climate mitigation,thereby laying a scientific foundation for international policy formulation and implementation.展开更多
As a water layer with significantly reduced dissolved oxygen(DO)in the ocean,the oxygen minimum zone(OMZ)plays a crucial role in regulating marine organism distribution,global material cycles,and climate change.Based ...As a water layer with significantly reduced dissolved oxygen(DO)in the ocean,the oxygen minimum zone(OMZ)plays a crucial role in regulating marine organism distribution,global material cycles,and climate change.Based on a systematic review of recent studies on OMZ,this paper summarizes the DO thresholds,structural characteristics,distribution patterns,formation and maintenance mechanisms,and driving factors of OMZ in the ocean in the context of global change.The DO thresholds of OMZ typically range from 20 to 100μmol L^(-1).Specifically,the threshold is mostly 20μmol L^(-1) in regions with intense OMZ,such as the Eastern Pacific and Northern Indian Oceans,while it is mostly 100μmol L^(-1) in regions with mild OMZ,including the Western Pacific and Atlantic.In terms of structure,the OMZ is mainly composed of three parts:the upper oxycline,the lower oxycline,and the OMZ core.Significant differences exist in the horizontal and vertical distributions of OMZ across different regions.OMZ is mainly concentrated in tropical and subtropical regions,with the widest distribution in the eastern tropical North Pacific.The upper boundary of OMZ is shallower(50-150 m)in significantly affected regions,whereas it is below 200 m in less affected regions.The formation of OMZ is governed by the continuous consumption of DO in the ocean interior,and the water exchange restriction caused by seawater stratification,whereas the maintenance of the hypoxic state of OMZ relies on two positive feedbacks:increased microbial oxygen consumption due to reduced animal feeding,and increased oxygen consumption by anaerobic metabolic products.In the context of global change,rising temperature is the main driver of OMZ expansion,reducing O_(2) solubility,increasing respiration and decomposition rates,and enhancing seawater stratification.Additionally,the structure and evolution of OMZ is also profoundly affected by ocean circulation such as thermohaline circulation,wind-driven circulation,and upwelling,as well as changes in wind stress,mesoscale eddies and freshwater flux.Future research should focus on establishing OMZ gradient thresholds and classification criteria based on the law of deoxygenation,improving the systematic understanding of the temporal and spatial variations of OMZ,and continuously strengthening studies on OMZ in the Western Pacific.展开更多
Atmospheric carbon dioxide(CO_(2))levels are escalating at an unprecedented rate,leading to the phenomenon of ocean acidification(OA).Parental exposure to acidification has the potential to enhance offspring resilienc...Atmospheric carbon dioxide(CO_(2))levels are escalating at an unprecedented rate,leading to the phenomenon of ocean acidification(OA).Parental exposure to acidification has the potential to enhance offspring resilience through cross-generation plasticity.In this study,we analyzed larval growth and transcriptomic profiles in the Pacific oyster,Crassostrea gigas,a species of significant ecological relevance,under both control and elevated CO_(2)conditions experienced by their parental generation.Our findings indicate that the oyster populations exposed to OA exhibited a higher incidence of abnormalities during the D-shaped larval stage,followed by accelerated growth at the eyed stage.Through a comparative transcriptomic investigation of eyed larvae(25 d after fertilization),we observed that parental exposure to OA substantially influenced the gene expression in the offspring.Genes associated with lipid catabolism and shell formation were notably upregulated in oysters with parental OA exposure,potentially playing a role in cross-generational conditioning and conferring resilience to OA stressors.These results underscore the profound impact of OA on oyster larval development via cross-generational mechanisms and shed light on the molecular underpinnings of cross-generation plasticity.展开更多
Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(EN...Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(ENSO)on summer precipitation in China.The inverse phase spatial distribution of sea surface temperature anomalies(SSTAs)in the southwest and northeast of the southern Indian Ocean is defined as the SIOD.Positive SIOD events(positive SSTAs in the southwest,negative SSTAs in the northeast)are associated with La Niña events(Central Pacific(CP)type),while negative SIOD events(negative SSTAs in the southwest,positive SSTAs in the northeast)are associated with El Niño events(Eastern Pacific(EP)type).Both SIOD and ENSO have certain impacts on summer precipitation in China.Precipitation in the Yangtze River basin decreases,while precipitation in southern China increases during pure positive SIOD(P_PSIOD)events.During pure negative SIOD(P_NSIOD)events,the changes in precipitation are exactly the opposite of those during P_PSIOD events,which may be due to differences in the cross-equatorial flow in the southern Indian Ocean,particularly in low-level Australian cross-equatorial flow.When positive SIOD and CP-type La Niña events occur simultaneously(PSIOD+La_Niña),precipitation increases in the Yangtze-Huaihe River basin,while it decreases in northern China.When negative SIOD and EP-type El Niño events occur simultaneously(NSIOD+El_Niño),precipitation in the Yangtze-Huaihe River basin is significantly lower than during P_NSIOD events.This is caused by differences in water vapor originating from the Pacific Ocean during different events.展开更多
As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operatio...As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.展开更多
In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural a...In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences.展开更多
Preferential policies,efficient government,and a favorable geographical location...a multitude of factors make the Hainan FTP a promising land for businesses.SOON after the Hainan Free Trade Port(FTP)launched special ...Preferential policies,efficient government,and a favorable geographical location...a multitude of factors make the Hainan FTP a promising land for businesses.SOON after the Hainan Free Trade Port(FTP)launched special customs operations at the end of 2025,private enterprises operating at its Yangpu Port began to benefit substantially from the favorable policies and surging growth momentum in the region.While riding on an ocean of opportunities opened by the FTP,local businesses are bringing the island to a new level of prosperity,and thriving together with it as a community of shared future.展开更多
文摘The problem of wave scattering by undulating bed topography in a two-layer ocean is investigated on the basis of linear theory. In a two-layer fluid with the upper layer having a free surface, there exist two modes of waves propagating at both the free surface of the upper layer and the interface between the two layers. Due to a wave train of a particular mode incident on an obstacle which is bottom-standing on the lower layer, reflected and transmitted waves of both modes are created by the obstacle. For small undulations on the bottom of the lower layer, a perturbation method is employed to obtain first-order reflection and transmission coefficients of both modes for incident wave trains of again both modes in terms of integrals involving the bed-shape fimction. For sinusoidal undulations, numerical results are presented graphically to illustrate the energy transfer between the waves of different modes by the undulating bed.
基金Project supported by the National Basic Research Program of China (Grant No. 2011CB403501)the National Natural Science Foundation of China (GrantNos. 41175058,41275062,and 11202106)
文摘A weak nonlinear model of a two-layer barotropic ocean with Rayleigh dissipation is built.The analytic asymptotic solution is derived in the mid-latitude stationary wind field,and the physical meaning of the corresponding problem is discussed.
文摘Open caissons are widely used in foundation engineering because of their load-bearing efficiency and adaptability in diverse soil conditions.However,accurately predicting their undrained bearing capacity in layered soils remains a complex challenge.This study presents a novel application of five ensemble machine(ML)algorithms-random forest(RF),gradient boosting machine(GBM),extreme gradient boosting(XGBoost),adaptive boosting(AdaBoost),and categorical boosting(CatBoost)-to predict the undrained bearing capacity factor(Nc)of circular open caissons embedded in two-layered clay on the basis of results from finite element limit analysis(FELA).The input dataset consists of 1188 numerical simulations using the Tresca failure criterion,varying in geometrical and soil parameters.The FELA was performed via OptumG2 software with adaptive meshing techniques and verified against existing benchmark studies.The ML models were trained on 70% of the dataset and tested on the remaining 30%.Their performance was evaluated using six statistical metrics:coefficient of determination(R²),mean absolute error(MAE),root mean squared error(RMSE),index of scatter(IOS),RMSE-to-standard deviation ratio(RSR),and variance explained factor(VAF).The results indicate that all the models achieved high accuracy,with R²values exceeding 97.6%and RMSE values below 0.02.Among them,AdaBoost and CatBoost consistently outperformed the other methods across both the training and testing datasets,demonstrating superior generalizability and robustness.The proposed ML framework offers an efficient,accurate,and data-driven alternative to traditional methods for estimating caisson capacity in stratified soils.This approach can aid in reducing computational costs while improving reliability in the early stages of foundation design.
基金supported by MHRD as researcher C.K.Neog received the MHRD Institute GATE scholarship from Govt.of India.
文摘This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerged cylindrical buoy.The system is modeled as a two-layer fluid with infinite horizontal extent and finite depth.The radiation problem is analyzed in the context of linear water waves.The fluid domain is divided into outer and inner zones,and mathematical solutions for the pitch radiating potential are derived for the corresponding boundary valve problem in these zones using the separation of variables approach.Using the matching eigenfunction expansion method,the unknown coefficients in the analytical expression of the radiation potentials are evaluated.The resulting radiation potential is then used to compute the added mass and damping coefficients.Several numerical results for the added mass and damping coefficients are investigated for numerous parameters,particularly the effects of the cylinder radius,the draft of the submerged cylinder,and the density proportion between the two fluid layers across different frequency ranges.The major findings are presented and discussed.
文摘A two-layer primitive equation model is developed in this paper. The capabilities of this model aretested by the use of multiyearly averaged January and July sea surface level pressure fields and windfields which can be diagnosed from the pressure fields. The results show that the ocean surface currentsand undercurrents in the second layer driven by the sea surface wind and the sea surface pressure areclose to the observation. The results are also compared with that of the IAP OGCM and the OSUOGCM.
基金supported by the Institute of Information&Communications Technology Planning&Evaluation(IITP)—Innovative Human Resource Development for Local Intellectualization program grant funded by the Korea government(MSIT)(IITP-2025-RS-2022-00156334)in part by Liaoning Province Nature Fund Project(2024-BSLH-214).
文摘Network Intrusion Detection System(NIDS)detection of minority class attacks is always a difficult task when dealing with attacks in complex network environments.To improve the detection capability of minority-class attacks,this study proposes an intrusion detection method based on a two-layer structure.The first layer employs a CNN-BiLSTM model incorporating an attention mechanism to classify network traffic into normal traffic,majority class attacks,and merged minority class attacks.The second layer further segments the minority class attacks through Stacking ensemble learning.The datasets are selected from the generic network dataset CIC-IDS2017,NSL-KDD,and the industrial network dataset Mississippi Gas Pipeline dataset to enhance the generalization and practical applicability of the model.Experimental results show that the proposed model achieves an overall detection accuracy of 99%,99%,and 95%on the CIC-IDS2017,NSL-KDD,and industrial network datasets,respectively.It also significantly outperforms traditional methods in terms of detection accuracy and recall rate for minority class attacks.Compared with the single-layer deep learning model,the two-layer structure effectively reduces the false alarm rate while improving the minority-class attack detection performance.The research in this paper not only improves the adaptability of NIDS to complex network environments but also provides a new solution for minority-class attack detection in industrial network security.
基金Supported by Talent Scientific Research Start-up Foundation of Wannan Medical College,No.WYRCQD2023045.
文摘BACKGROUND The early diagnosis rate of pancreatic ductal adenocarcinoma(PDAC)is low and the prognosis is poor.It is important to develop an interpretable noninvasive early diagnostic model in clinical practice.AIM To develop an interpretable noninvasive early diagnostic model for PDAC using plasma extracellular vesicle long RNA(EvlRNA).METHODS The diagnostic model was constructed based on plasma EvlRNA data.During the process of establishing the model,EvlRNA-index was introduced,and four algorithms were adopted to calculate EvlRNA-index.After the model was successfully constructed,performance evaluation was conducted.A series of bioinformatics methods were adopted to explore the potential mechanism of EvlRNA-index as the input feature of the model.And the relationship between key characteristics and PDAC were explored at the single-cell level.RESULTS A novel interpretable machine learning framework was developed based on plasma EvlRNA.In this framework,a two-layer classifier was established.A new concept was proposed:EvlRNA-index.Based on EvlRNA-index,a cancer diagnostic model was established,and a good diagnostic effect was achieved.The accuracy of PDACandCPvsHealth-Probabilistic PCA Index-SVM(PDAC and chronic pancreatitis vs health-probabilistic principal component analysis index-support vector machine)(1-18)was 91.51%,with Mathew’s correlation coefficient 0.7760 and area under the curve 0.9560.In the second layer of the model,the accuracy of PDACvsCP-Probabilistic PCA Index-RF(PDAC vs chronic pancreatitis-probabilistic principal component analysis index-random forest)(2-17)was 93.83%,with Mathew’s correlation coefficient 0.8422 and area under the curve 0.9698.Forty-nine PDAC-related genes were identified,among which 16 were known,inferring that the remaining ones were also PDAC-related genes.CONCLUSION An interpretable two-layer machine learning framework was proposed for early diagnosis and prediction of PDAC based on plasma EvlRNA,providing new insights into the clinical value of EvlRNA.
基金supported by the Basic Scientific Research Business Fund Project of Higher Education Institutions in Heilongjiang Province(145409601)the First Batch of Experimental Teaching and Teaching Laboratory Construction Research Projects in Heilongjiang Province(SJGZ20240038).
文摘In the wake of major natural disasters or human-made disasters,the communication infrastruc-ture within disaster-stricken areas is frequently dam-aged.Unmanned aerial vehicles(UAVs),thanks to their merits such as rapid deployment and high mobil-ity,are commonly regarded as an ideal option for con-structing temporary communication networks.Con-sidering the limited computing capability and battery power of UAVs,this paper proposes a two-layer UAV cooperative computing offloading strategy for emer-gency disaster relief scenarios.The multi-agent twin delayed deep deterministic policy gradient(MATD3)algorithm integrated with prioritized experience replay(PER)is utilized to jointly optimize the scheduling strategies of UAVs,task offloading ratios,and their mobility,aiming to diminish the energy consumption and delay of the system to the minimum.In order to address the aforementioned non-convex optimiza-tion issue,a Markov decision process(MDP)has been established.The results of simulation experiments demonstrate that,compared with the other four base-line algorithms,the algorithm introduced in this paper exhibits better convergence performance,verifying its feasibility and efficacy.
基金supported by the National Natural Science Foundation of China(Grant No.92258303)the National Key Research and Development Program of China(Grant Nos.2024YFF0506704 and 2023YFF0803404).
文摘Ocean geoscience is a highly integrated and interdisciplinary field that plays a critical role in understanding the interaction between Earth’s lithosphere,hydrosphere,atmosphere,biosphere,and anthroposphere.Recent years have seen tremendous progress in global ocean research,driven by rapid advancements in deep-sea manned and unmanned submersibles,ocean drilling,seafloor observatories,big data assimilation,and supercomputing simulations.Representative examples of breakthroughs are highlighted in this work:(1)Probing sub-seafloor processes.A 10,000-meter ocean-bottom seismometer array has achieved high-resolution imaging of the deepest ocean on the Earth-the Challenger Deep of the Mariana Trench,revealing the role of key tectonic and hydrological processes within the subduction zone.The first sub-ice seafloor seismic and magnetotelluric experiments were successfully conducted at the Arctic Gakkel Ridge,providing significant insights into the dynamics of ultraslow seafloor spreading.(2)Exploration of seafloor resources.Near-seafloor investigations employing underwater robotics and multi-sensor systems have been carried out in areas of hydrothermal vents and cold seeps at global locations,including the Southwest Indian Ridge.These efforts have combined geophysical,oceanographic,chemical,and biological observations with extensive seafloor sampling.(3)Interdisciplinary research of complex catastrophic events.High-resolution simulations integrating ocean observations with supercomputing modeling have made it possible to fully model earthquake-induced seafloor deformation,tsunami propagation,and ocean basin-scale transport of the Fukushima Power Plant-derived radionuclides associated with the 2011 Tohoku earthquake.Among the world’s three major oceans,the Indian Ocean is still relatively underexplored.Major scientific challenges include elucidating crust-mantle interaction,air-sea dynamic coupling,large-scale marine hazards,and responses of ecosystems to major environmental changes,all of which require interdisciplinary collaboration.Future efforts should focus on developing intelligent unmanned observation platform systems,big data and digital twins,and AI-driven hazard modeling.Meanwhile,higher educational reforms should emphasize fostering a new generation of students and young scientists with a solid background and strong critical analysis skills to accelerate technological innovation.
文摘On July 2^(nd),2025,32 scientists representing 15 countries gathered at Tartu,Estonia to make on-site endorsements for the Global ONCE(Ocean Negative Carbon Emissions)Program at the 12th INTECOL Wetlands Conference.This marks a significant milestone for ONCE in establishing a systematic framework for coastal wetland carbon sequestration research and global collaboration(Figs.1,2).Coastal wetlands are critical transition zones linking terrestrial and marine ecosystems,yet they face severe degradation from anthropogenic land-based activities and sea level rise that propagate impacts to the ocean.As a UN Ocean Decade Program,the Global ONCE Program champions interdisciplinary and cross-regional collaboration to enhance carbon sequestration in the ocean and coastal wetlands through science and innovation.Aligned with the Tartu Declaration on Wetlands that includes resolutions to promote the rights of global wetlands(especially peatlands)and advance the discipline of wetland science based on facts,this initiative addresses key knowledge gaps in land-ocean interactions.The goal is to harness the full potential of coastal wetlands and ocean systems for climate mitigation,thereby laying a scientific foundation for international policy formulation and implementation.
基金supported by the National Natural Science Foundation of China(Grant Nos.42206135,42476204)the Shandong Provincial Natural Science Foundation(Grant Nos.ZR2025MS664,ZR2025MS611,ZR2022QD019).
文摘As a water layer with significantly reduced dissolved oxygen(DO)in the ocean,the oxygen minimum zone(OMZ)plays a crucial role in regulating marine organism distribution,global material cycles,and climate change.Based on a systematic review of recent studies on OMZ,this paper summarizes the DO thresholds,structural characteristics,distribution patterns,formation and maintenance mechanisms,and driving factors of OMZ in the ocean in the context of global change.The DO thresholds of OMZ typically range from 20 to 100μmol L^(-1).Specifically,the threshold is mostly 20μmol L^(-1) in regions with intense OMZ,such as the Eastern Pacific and Northern Indian Oceans,while it is mostly 100μmol L^(-1) in regions with mild OMZ,including the Western Pacific and Atlantic.In terms of structure,the OMZ is mainly composed of three parts:the upper oxycline,the lower oxycline,and the OMZ core.Significant differences exist in the horizontal and vertical distributions of OMZ across different regions.OMZ is mainly concentrated in tropical and subtropical regions,with the widest distribution in the eastern tropical North Pacific.The upper boundary of OMZ is shallower(50-150 m)in significantly affected regions,whereas it is below 200 m in less affected regions.The formation of OMZ is governed by the continuous consumption of DO in the ocean interior,and the water exchange restriction caused by seawater stratification,whereas the maintenance of the hypoxic state of OMZ relies on two positive feedbacks:increased microbial oxygen consumption due to reduced animal feeding,and increased oxygen consumption by anaerobic metabolic products.In the context of global change,rising temperature is the main driver of OMZ expansion,reducing O_(2) solubility,increasing respiration and decomposition rates,and enhancing seawater stratification.Additionally,the structure and evolution of OMZ is also profoundly affected by ocean circulation such as thermohaline circulation,wind-driven circulation,and upwelling,as well as changes in wind stress,mesoscale eddies and freshwater flux.Future research should focus on establishing OMZ gradient thresholds and classification criteria based on the law of deoxygenation,improving the systematic understanding of the temporal and spatial variations of OMZ,and continuously strengthening studies on OMZ in the Western Pacific.
基金Supported by the Key Research and Development Program of Shandong(No.2022LZGC015)the National Key R&D Program of China(No.2022YFD2401400)+1 种基金the Taishan Scholars Program,the National Key R&D Program of China(No.2022YFD2400304)the Agricultural Seed Project of Shandong Key R&D Program(No.2024LZGCQY003)。
文摘Atmospheric carbon dioxide(CO_(2))levels are escalating at an unprecedented rate,leading to the phenomenon of ocean acidification(OA).Parental exposure to acidification has the potential to enhance offspring resilience through cross-generation plasticity.In this study,we analyzed larval growth and transcriptomic profiles in the Pacific oyster,Crassostrea gigas,a species of significant ecological relevance,under both control and elevated CO_(2)conditions experienced by their parental generation.Our findings indicate that the oyster populations exposed to OA exhibited a higher incidence of abnormalities during the D-shaped larval stage,followed by accelerated growth at the eyed stage.Through a comparative transcriptomic investigation of eyed larvae(25 d after fertilization),we observed that parental exposure to OA substantially influenced the gene expression in the offspring.Genes associated with lipid catabolism and shell formation were notably upregulated in oysters with parental OA exposure,potentially playing a role in cross-generational conditioning and conferring resilience to OA stressors.These results underscore the profound impact of OA on oyster larval development via cross-generational mechanisms and shed light on the molecular underpinnings of cross-generation plasticity.
基金supported by the National Natural Science Foundation of China[grant numbers 41975087,U2242212,and 41975085]supported by the National Natural Science Foundation of China[grant number U2242212]。
文摘Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(ENSO)on summer precipitation in China.The inverse phase spatial distribution of sea surface temperature anomalies(SSTAs)in the southwest and northeast of the southern Indian Ocean is defined as the SIOD.Positive SIOD events(positive SSTAs in the southwest,negative SSTAs in the northeast)are associated with La Niña events(Central Pacific(CP)type),while negative SIOD events(negative SSTAs in the southwest,positive SSTAs in the northeast)are associated with El Niño events(Eastern Pacific(EP)type).Both SIOD and ENSO have certain impacts on summer precipitation in China.Precipitation in the Yangtze River basin decreases,while precipitation in southern China increases during pure positive SIOD(P_PSIOD)events.During pure negative SIOD(P_NSIOD)events,the changes in precipitation are exactly the opposite of those during P_PSIOD events,which may be due to differences in the cross-equatorial flow in the southern Indian Ocean,particularly in low-level Australian cross-equatorial flow.When positive SIOD and CP-type La Niña events occur simultaneously(PSIOD+La_Niña),precipitation increases in the Yangtze-Huaihe River basin,while it decreases in northern China.When negative SIOD and EP-type El Niño events occur simultaneously(NSIOD+El_Niño),precipitation in the Yangtze-Huaihe River basin is significantly lower than during P_NSIOD events.This is caused by differences in water vapor originating from the Pacific Ocean during different events.
基金funded by Nansha District Science and Technology Project(Grant Number.2024ZD008)funded by China Geological Survey(Grant number:No.DD20230066,DD20242659).
文摘As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.
基金supported by the CAS Strategic Priority Research Program(No.XDB0760102),the Ministry of Science and Technology of China(No.2022YFF0802501)the Major Science and Technology Infrastructure Maintenance and Transformation Project of the Chinese Academy of Sciences,Shanghai Science and Technology Innovation Action Plan-Phospherus Project(No.23YF1426200)the National Key Research and Development Program of China(No.2024YFE0212200).
文摘In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences.
文摘Preferential policies,efficient government,and a favorable geographical location...a multitude of factors make the Hainan FTP a promising land for businesses.SOON after the Hainan Free Trade Port(FTP)launched special customs operations at the end of 2025,private enterprises operating at its Yangpu Port began to benefit substantially from the favorable policies and surging growth momentum in the region.While riding on an ocean of opportunities opened by the FTP,local businesses are bringing the island to a new level of prosperity,and thriving together with it as a community of shared future.
