Hydrate-based gas separation offers a promising approach for coalbed methane recovery,reaching energy conservation and emissions reduction.This study innovatively applied high-gravity technology to enhance hydrate for...Hydrate-based gas separation offers a promising approach for coalbed methane recovery,reaching energy conservation and emissions reduction.This study innovatively applied high-gravity technology to enhance hydrate formation in separating 25%CH_(4)/67%N_(2)/8%O_(2) for achieving rapid and efficient methane recovery.Systematic investigations were conducted at 283.2 K and 3.0 MPa with tetrahydrofuran at a molar concentration of 5.56%and L-tryptophan at a mass concentration of 0.5%additives,first evaluating liquid flow rate effects(0–20 mL/min)on mixed hydrate kinetic performance and separation efficiency,followed by rotating speed optimization(0–1200 r·min^(-1))under the optimal liquid flow rate.The high-gravity system amplified the gas–liquid contact area by~1155 times through cascaded liquid supply and secondary shear effects,methane molecules entered the hydrate phase rapidly under the highest driving force with the significantly intensified mass transfer.Optimal conditions(20 mL/min,600 r·min^(-1))yielded an exceptional initial hydrate growth rate of 58.59 mmol/(mol·h)and methane recovery of 50.76%,about 71.33 and 0.58 times higher than the static system,respectively.Gas chromatography and Raman spectrometer analyses revealed superior methane enrichment in hydrate phase at 90%gas uptake completion,with a concurrent 41.17%reduction in process duration.These findings demonstrate the efficacy of high-gravity-enhanced hydrate technology for coalbed methane separation,offering valuable insights for optimizing clean energy utilization.展开更多
The long-term stability of CO_(2) storage represents a pivotal challenge in geological CO_(2) storage(CGS),particularly within deep saline aquifers characterized by complex fault-block systems.While the injection site...The long-term stability of CO_(2) storage represents a pivotal challenge in geological CO_(2) storage(CGS),particularly within deep saline aquifers characterized by complex fault-block systems.While the injection sites and rate under different fault structures will directly affect the CO_(2) storage effect and the risk of leakage.This study investigates the Gaoyou Sag in the Subei Basin,a representative fault-block reservoir,through an integrated numerical-experimental approach.A three-dimensional simulation model incorporating multiphase flow dynamics was developed to characterize subsurface CO_(2) transport and dissolution processes.A novel fault seal capacity evaluation framework was proposed,integrating three critical geological indices(fault throw/reservoir thickness/caprock thicknesses)with the coupling of formation physical properties,temperature,and pressure for the rational selection of injection sites and rates.The results show that Optimal storage performance is observed when the fault throw is lower than the reservoir and caprock thicknesses.Furthermore,higher temperature and pressure promote the dissolution and diffusion of CO_(2),while compared to the structural form of faults,the physical properties of faults have a more significant effect on CO_(2) leakage.The larger reservoir space and the presence of an interlayer reduce the risk of CO_(2) leakage,and augmenting storage potential.Decreasing the injection rate increases the proportion of dissolved CO_(2),thereby enhancing the safety of CO_(2) storage.展开更多
Refinery scheduling attracts increasing concerns in both academic and industrial communities in recent years.However, due to the complexity of refinery processes, little has been reported for success use in real world...Refinery scheduling attracts increasing concerns in both academic and industrial communities in recent years.However, due to the complexity of refinery processes, little has been reported for success use in real world refineries. In academic studies, refinery scheduling is usually treated as an integrated, large-scale optimization problem,though such complex optimization problems are extremely difficult to solve. In this paper, we proposed a way to exploit the prior knowledge existing in refineries, and developed a decision making system to guide the scheduling process. For a real world fuel oil oriented refinery, ten adjusting process scales are predetermined. A C4.5 decision tree works based on the finished oil demand plan to classify the corresponding category(i.e. adjusting scale). Then,a specific sub-scheduling problem with respect to the determined adjusting scale is solved. The proposed strategy is demonstrated with a scheduling case originated from a real world refinery.展开更多
With the increasing demand of energy and the limitation of bottom-fixed wind turbines in moderate and deep waters,floating offshore wind turbines are doomed to be the right technical choice and they are bound to enter...With the increasing demand of energy and the limitation of bottom-fixed wind turbines in moderate and deep waters,floating offshore wind turbines are doomed to be the right technical choice and they are bound to enter a new era of rapid development.The mooring system is a vital system of a floating wind turbine for station-keeping under harsh environmental conditions.In terms of existing floating wind turbine projects,this paper is devoted to discussing the current status of mooring systems and mooring equipment.This paper also presents the mooring analysis methods and points out the technical difficulties and challenges in mooring design,installation,operation and maintenance stages.Finally,the developing trends of the mooring system are summarized,aiming to provide a reference for future mooring research.展开更多
Intermittent demand forecasting is an important challenge in the process of smart supply chain transformation,and accurate demand forecasting can reduce costs and increase efficiency for enterprises.This study propose...Intermittent demand forecasting is an important challenge in the process of smart supply chain transformation,and accurate demand forecasting can reduce costs and increase efficiency for enterprises.This study proposes an intermittent demand combination forecasting method based on internal and external data,builds intermittent demand feature engineering from the perspective of machine learning,predicts the occurrence of demand by classification model,and predicts non-zero demand quantity by regression model.Based on the strategy selection on the inventory side and the stocking needs on the replenishment side,this study focuses on the optimization of the classification problem,incorporates the internal and external data of the enterprise,and proposes two combination forecasting optimization methods on the basis of the best classification threshold searching and transfer learning,respectively.Based on the real data of auto after-sales business,these methods are evaluated and validated in multiple dimensions.Compared with other intermittent forecasting methods,the models proposed in this study have been improved significantly in terms of classification accuracy and forecasting precision,which validates the potential of combined forecasting framework for intermittent demand and provides an empirical study of the framework in industry practice.The results show that this research can further provide accurate upstream inputs for smart inventory and guarantee intelligent supply chain decision-making in terms of accuracy and efficiency.展开更多
Submarine pipelines are critical infrastructures for offshore energy transport and communications. Understanding their structural response to near-field explosions is crucial for enhancing their blast resistance and o...Submarine pipelines are critical infrastructures for offshore energy transport and communications. Understanding their structural response to near-field explosions is crucial for enhancing their blast resistance and operational safety. This study presents a computational study on the interaction between explosion-induced bubbles and a seabed-mounted pipeline. A recently developed computational framework is employed, which couples a compressible fluid solver with a finite element structural solver via a partitioned procedure. An embedded boundary method and a level-set method are employed to handle the fluid-structure and gas-liquid interfaces. Using this framework, we analyze the flow field evolution, bubble dynamics, and transient pipe deformation. Two distinct response modes are identified: periodic oscillation under low-pressure loading and downward collapse triggered by high-pressure loading and bubble jet impact. Specifically, under high-pressure conditions, the pipe initially deforms inward, generating a localized high-pressure zone within the concave region. During structural rebound, the trapped fluid is expelled upward, giving rise to a bubble jet. Further parametric studies on the pipe's internal pressure, wall thickness, and support angle reveal several key insights. A higher internal pressure delays structural collapse, and a greater pipe thickness results in more uniform implosion morphologies. The support angle strongly influences the collapse dynamics, with the shortest collapse time occurring at 60 °. These findings offer new insights for the protective design of submarine pipelines.展开更多
Some deep-sea microbes may incorporate inorganic carbon to reduce CO_(2) emission to upper layer and atmosphere.How the microbial inhabitants can be affected under addition of bicarbonate has not been studied using in...Some deep-sea microbes may incorporate inorganic carbon to reduce CO_(2) emission to upper layer and atmosphere.How the microbial inhabitants can be affected under addition of bicarbonate has not been studied using in situ fixed and lysed samples.In this study,we cultivated 40 L natural bottom water at~1000 m depth with a final concentration of 0.1 mmol/L bicarbonate for 40 min and applied multiple in situ nucleic acids collection(MISNAC)apparatus for nucleic acids extraction from the cultivation.Our classification result of the cultivation sample showed a distinct microbial community structure,compared with the samples obtained by Niskin bottle and six working units of MISNAC.Except for notable enrichment of Alteromonas,we detected prevalence of Asprobacter,Ilumatobacter and Saccharimonadales in the cultivation.Deep-sea lineages of Euryarchaeota,SAR406,SAR202 and SAR324 were almost completely absent from the cultivation and Niskin samples.This study revealed the dominant microbes affected by bicarbonate addition and Niskin sampling,which suggested rapid responses of deep-sea microbes to the environmental changes.展开更多
With the growing global focus on reducing greenhouse gas emissions,hydrate-based CO_(2) sequestration in marine sediments has gained wide attention due to its high storage capacity and thermodynamic stability of CO_(2...With the growing global focus on reducing greenhouse gas emissions,hydrate-based CO_(2) sequestration in marine sediments has gained wide attention due to its high storage capacity and thermodynamic stability of CO_(2) hydrate.However,the limited understanding of the CO_(2) hydrate stability zone,particularly in the presence of abundant swelling type clays,i.e.,Na-montmorillonite,warrants further investigation.This study examines the thermodynamic effects of Na-montmorillonite on the phase equilibria of CO_(2) hydrate under varying water contents(30-80 wt%).The results reveal that Na-montmorillonite inhibits CO_(2) hydrate formation thermodynamically with a significant inhibition effect as the water content decreases.A notable leftward shift of up to 2.7 K in the phase equilibrium temperature was observed at 3.90 MPa with 30 wt%water content.A thermodynamic model was developed integrating the diffuse double layer theory and Hu-Lee-Sum water activity correlation model into the classical Chen-Guo model.The proposed model demonstrated high accuracy with the measured data with an absolute average deviation of pressure below 0.5%.The thermodynamic inhibition effect is attributed to the decrease in water activity caused by the Na+exchange in the diffuse double layer on the clay surface.This study also presents the implication of swelling type clay on the CO_(2) hydrate stability zone in a permafrost setting,highlighting its impact on the CO_(2) storage site selection and CO_(2) storage capacity.These findings provide valuable insights for optimizing hydrate-based CO_(2) sequestration strategies,contributing to CO_(2) mitigation technology.展开更多
To enhance the efficiency of wind energy harvesters,aerodynamic modifications to bluff bodies prove highly effective.This study introduces two innovative galloping piezoelectric energy harvesters(GPEHs)equipped with t...To enhance the efficiency of wind energy harvesters,aerodynamic modifications to bluff bodies prove highly effective.This study introduces two innovative galloping piezoelectric energy harvesters(GPEHs)equipped with two symmetrical splitters on a cuboid bluff body:GPEH with upstream splitters(GPEH-US)and GPEH with downstream splitters(GPEH-DS).Wind tunnel experiments evaluated the impact of splitter angle and length on energy harvesting performance across varying wind speeds.The results indicate that larger splitter angles and shorter lengths are more favorable for energy harvesting in GPEH-US.The optimal configuration,determined as GPEH-US with α=90°,L=0.4D,reduces the threshold wind speed,expands the effective wind speed range for energy harvesting,and increases maximum voltage and power output by over 99%,301%,respectively,compared with conventional GPEH.Conversely,GPEH-DS are less effective for energy harvesting but demonstrate potential in vibration control applications.Computational fluid dynamics(CFD)simulations using the OpenFOAM toolbox qualitatively elucidate the physical mechanisms driving these results.A larger splitter angle enables secondary small-scale vortices(SV)to absorb more energy,accelerates boundary layer separation,intensifies and disorderly vortex shedding,enhances aerodynamic instability,and improves energy harvesting performance.展开更多
Recently,the fifth-generation(5G)of wireless networks mainly focuses on the terrestrial applications.However,the well-developed emerging technologies in 5G are hardly applied to the maritime communications,resulting f...Recently,the fifth-generation(5G)of wireless networks mainly focuses on the terrestrial applications.However,the well-developed emerging technologies in 5G are hardly applied to the maritime communications,resulting from the lack of communication infrastructure deployed on the vast ocean,as well as different characteristics of wireless propagation environment over the sea and maritime user distribution.To satisfy the expected plethora of broadband communications and multimedia applications on the ocean,a brand-new maritime information network with a comprehensive coverage capacity in terms of all-hour,all-weather,and all-sea-area has been expected as a revolutionary paradigm to extend the terrestrial capacity of enhanced broadband,massive access,ultra-reliable,and low-latency to the vast ocean.Further considering the limited available resource of maritime communication infrastructure,the convergence of broadband and broadcast/multicast can be regarded as a possible yet practical solution for realizing an efficient and flexible resource configuration with high quality of services.Moreover,according to such multi-functionality and all-coverage maritime information network,the monitoring and sensing of vast ocean area relying on massive Ocean of Things and advanced radar techniques can be also supported.Concerning these issues above,this study proposes a Software Defined Networking(SDN)based Maritime Giant Cellular Network(MagicNet)architecture for broadband and multimedia services.Based on this network,the convergence techniques of broadband and broadcast/multicast,and their supporting for maritime monitoring and marine sensing are also introduced and surveyed.展开更多
Harmful cyanobacterial blooms(HCBs)pose a global ecological threat.Ultraviolet C(UVC)irradiation at 254 nm is a promising method for controlling cyanobacterial proliferation,but the growth suppression is temporary.Res...Harmful cyanobacterial blooms(HCBs)pose a global ecological threat.Ultraviolet C(UVC)irradiation at 254 nm is a promising method for controlling cyanobacterial proliferation,but the growth suppression is temporary.Resuscitation remains a challenge with UVC application,necessitating alternative strategies for lethal effects.Here,we show synergistic inhibition of Microcystis aeruginosa using ultraviolet A(UVA)pre-irradiation before UVC.We find that low-dosage UVA pre-irradiation(1.5 J cm^(−2))combined with UVC(0.085 J cm^(−2))reduces 85%more cell densities compared to UVC alone(0.085 J cm^(−2))and triggers mazEF-mediated regulated cell death(RCD),which led to cell lysis,while high-dosage UVA pre-irradiations(7.5 and 14.7 J cm^(−2))increase cell densities by 75-155%.Our oxygen evolution tests and transcriptomic analysis indicate that UVA pre-irradiation damages photosystem I(PSI)and,when combined with UVC-induced PSII damage,synergistically inhibits photosynthesis.However,higher UVA dosages activate the SOS response,facilitating the repair of UVC-induced DNA damage.This study highlights the impact of UVA pre-irradiation on UVC suppression of cyanobacteria and proposes a practical strategy for improved HCBs control.展开更多
With the rapid expansion of offshore wind farms(OWFs)in remote regions,the study of highly reliable electrical collector systems(ECSs)has become increasingly important.Post-fault network recovery is considered as an e...With the rapid expansion of offshore wind farms(OWFs)in remote regions,the study of highly reliable electrical collector systems(ECSs)has become increasingly important.Post-fault network recovery is considered as an effective mea-sure of reliability enhancement.In this paper,we propose a smart switch configuration that facilitates network recovery,making it well-suited for ECSs operating in harsh environ-ments.To accommodate the increased complexity of ECSs,a novel reliability assessment(RA)method considering detailed switch configuration is devised.This method effectively identi-fies the minimum outage propagation areas and incorporates post-fault network recovery strategies.The optimal normal op-erating state and network reconfiguration strategies that maxi-mize ECS reliability can be obtained after optimization.Case studies on real-life OwFs validate the effectiveness and superi-ority of the proposed RA method compared with the traditional sequential Monte-Carlo simulation method.Moreover,numeri-cal tests demonstrate that the proposed switch configuration,in conjunction with proper topology and network recovery,achieves the highest benefits across a wide range of operating conditions.展开更多
Atmospheric Kármán vortex streets,which frequently emerge on the leeward side of isolated islands under specific atmospheric conditions,play a critical role in large-scale atmospheric dynamics.However,their ...Atmospheric Kármán vortex streets,which frequently emerge on the leeward side of isolated islands under specific atmospheric conditions,play a critical role in large-scale atmospheric dynamics.However,their automated detection and the influence of atmospheric variables on their formation remain insufficiently explored.Here,we firstly developed an object detection dataset utilizing 20 years of cloud imagery from the MODIS aboard the Terra and Aqua satellites,facilitating the application of artificial intelligence algorithms for the automated detection of Kármán vortex streets.Given that these vortex streets can manifest under both cloudy and cloudfree conditions,we further assessed the contribution of various spectral bands to vortex detection by implying a multi-channel classification network.This network,built upon a custom-designed miniResNet dual-level classification network and trained on MODls HDFformat sensor data,demonstrates that the dataset is particularly suited for detecting Kármán vortex streets in cloudy conditions.Different types of advanced algorithms were applied on the dataset,yielding baseline performance metrics and potential detection methods.Additionally,we proposed two optimization strategies tailored to Kármán vortex streets detection.First,leveraging the intrinsic properties of vortex structures,we introduced a Gamma loss optimization for bounding box aspect ratios,which significantly enhanced performance across six YoLO-based models.Second,we investigated the role of atmospheric variables in vortex formation and incorporated an auxiliary-task-enhanced learning approach to further refine detection accuracy,drawing upon findings from our recently published work.In summary,this study provides a novel dataset that supports meteorological and climatological research,addressing a critical gap in atmospheric data.Furthermore,the proposed auxiliary optimization strategies highlight the distinct challenges of Kármán vortex streets detection compared to conventional object detection,underscoring the unique structural and atmospheric characteristics of these phenomena.展开更多
Removing high-risk and persistent contaminants from water is challenging,because they typically exist at low concentrations in complex water matrices.Electrified flow-through technologies are viable to overcome the li...Removing high-risk and persistent contaminants from water is challenging,because they typically exist at low concentrations in complex water matrices.Electrified flow-through technologies are viable to overcome the limitations induced by mass transport for efficient contaminant removal.Modifying the local environment of the flow-through electrodes offers opportunities to further improve the reaction kinetics and selectivity for achieving near-complete removal of these contaminants from water.Here,we present state-of-the-art local environment modification approaches that can be incorporated into electrified flow-through technologies to intensify water treatment.We first show methods of nanospace incorporation,local geometry adjustment,and microporous structure optimization that can induce spatial confinement,enhanced local electric field,and microperiodic vortex,respectively,for local environment modification.We then discuss why local environment modification can complement the flow-through electrodes for improving the reaction rate and selectivity.Finally,we outline appropriate scenarios of intensifying electrified flow-through technologies through local environment modification for fit-for-purpose water treatment applications.展开更多
基金The financial support from the Nature Scientific Foundation of Heilongjiang Province(No.YQ2022E041)the Postdoctoral Research Start-up Funds in Heilongjiang Province(No.2023BSH14)the Basic scientific research project of Heilongjiang Provincial University(No.2024-KYYWF-1090)。
文摘Hydrate-based gas separation offers a promising approach for coalbed methane recovery,reaching energy conservation and emissions reduction.This study innovatively applied high-gravity technology to enhance hydrate formation in separating 25%CH_(4)/67%N_(2)/8%O_(2) for achieving rapid and efficient methane recovery.Systematic investigations were conducted at 283.2 K and 3.0 MPa with tetrahydrofuran at a molar concentration of 5.56%and L-tryptophan at a mass concentration of 0.5%additives,first evaluating liquid flow rate effects(0–20 mL/min)on mixed hydrate kinetic performance and separation efficiency,followed by rotating speed optimization(0–1200 r·min^(-1))under the optimal liquid flow rate.The high-gravity system amplified the gas–liquid contact area by~1155 times through cascaded liquid supply and secondary shear effects,methane molecules entered the hydrate phase rapidly under the highest driving force with the significantly intensified mass transfer.Optimal conditions(20 mL/min,600 r·min^(-1))yielded an exceptional initial hydrate growth rate of 58.59 mmol/(mol·h)and methane recovery of 50.76%,about 71.33 and 0.58 times higher than the static system,respectively.Gas chromatography and Raman spectrometer analyses revealed superior methane enrichment in hydrate phase at 90%gas uptake completion,with a concurrent 41.17%reduction in process duration.These findings demonstrate the efficacy of high-gravity-enhanced hydrate technology for coalbed methane separation,offering valuable insights for optimizing clean energy utilization.
基金the Beijing Natural Science Foundation(No.8232044)the Science Foundation of China University of Petroleum,Beijing(No.2462023BJRC030).
文摘The long-term stability of CO_(2) storage represents a pivotal challenge in geological CO_(2) storage(CGS),particularly within deep saline aquifers characterized by complex fault-block systems.While the injection sites and rate under different fault structures will directly affect the CO_(2) storage effect and the risk of leakage.This study investigates the Gaoyou Sag in the Subei Basin,a representative fault-block reservoir,through an integrated numerical-experimental approach.A three-dimensional simulation model incorporating multiphase flow dynamics was developed to characterize subsurface CO_(2) transport and dissolution processes.A novel fault seal capacity evaluation framework was proposed,integrating three critical geological indices(fault throw/reservoir thickness/caprock thicknesses)with the coupling of formation physical properties,temperature,and pressure for the rational selection of injection sites and rates.The results show that Optimal storage performance is observed when the fault throw is lower than the reservoir and caprock thicknesses.Furthermore,higher temperature and pressure promote the dissolution and diffusion of CO_(2),while compared to the structural form of faults,the physical properties of faults have a more significant effect on CO_(2) leakage.The larger reservoir space and the presence of an interlayer reduce the risk of CO_(2) leakage,and augmenting storage potential.Decreasing the injection rate increases the proportion of dissolved CO_(2),thereby enhancing the safety of CO_(2) storage.
基金Supported by the National Natural Science Foundation of China(21706282,21276137,61273039,61673236)Science Foundation of China University of Petroleum,Beijing(No.2462017YJRC028)the National High-tech 863 Program of China(2013AA 040702)
文摘Refinery scheduling attracts increasing concerns in both academic and industrial communities in recent years.However, due to the complexity of refinery processes, little has been reported for success use in real world refineries. In academic studies, refinery scheduling is usually treated as an integrated, large-scale optimization problem,though such complex optimization problems are extremely difficult to solve. In this paper, we proposed a way to exploit the prior knowledge existing in refineries, and developed a decision making system to guide the scheduling process. For a real world fuel oil oriented refinery, ten adjusting process scales are predetermined. A C4.5 decision tree works based on the finished oil demand plan to classify the corresponding category(i.e. adjusting scale). Then,a specific sub-scheduling problem with respect to the determined adjusting scale is solved. The proposed strategy is demonstrated with a scheduling case originated from a real world refinery.
基金The financial supports received from China National Science Foundation Program(52071186)Shenzhen Science and Technology Program(Grant No.KQTD20200820113004005)+1 种基金the Key Promotion Program of High Quality Marine Economy Development by Guangdong Province of China(GDNRC[2022]33)The Major Program of Stable Sponsorship for Higher Institutions(Shenzhen Science&Technology Commission,WDZC20200819174646001)are greatly acknowledged.
文摘With the increasing demand of energy and the limitation of bottom-fixed wind turbines in moderate and deep waters,floating offshore wind turbines are doomed to be the right technical choice and they are bound to enter a new era of rapid development.The mooring system is a vital system of a floating wind turbine for station-keeping under harsh environmental conditions.In terms of existing floating wind turbine projects,this paper is devoted to discussing the current status of mooring systems and mooring equipment.This paper also presents the mooring analysis methods and points out the technical difficulties and challenges in mooring design,installation,operation and maintenance stages.Finally,the developing trends of the mooring system are summarized,aiming to provide a reference for future mooring research.
基金This work was supported jointly by the funding from Shandong In-dustrial Internet Innovation and Entrepreneurship Community,the Na-tional Natural Science Foundation of China(Grant No.:71810107003)the National Social Science Foundation of China(Grant No.:18ZDA109).
文摘Intermittent demand forecasting is an important challenge in the process of smart supply chain transformation,and accurate demand forecasting can reduce costs and increase efficiency for enterprises.This study proposes an intermittent demand combination forecasting method based on internal and external data,builds intermittent demand feature engineering from the perspective of machine learning,predicts the occurrence of demand by classification model,and predicts non-zero demand quantity by regression model.Based on the strategy selection on the inventory side and the stocking needs on the replenishment side,this study focuses on the optimization of the classification problem,incorporates the internal and external data of the enterprise,and proposes two combination forecasting optimization methods on the basis of the best classification threshold searching and transfer learning,respectively.Based on the real data of auto after-sales business,these methods are evaluated and validated in multiple dimensions.Compared with other intermittent forecasting methods,the models proposed in this study have been improved significantly in terms of classification accuracy and forecasting precision,which validates the potential of combined forecasting framework for intermittent demand and provides an empirical study of the framework in industry practice.The results show that this research can further provide accurate upstream inputs for smart inventory and guarantee intelligent supply chain decision-making in terms of accuracy and efficiency.
基金supported by the National Key R&D Program of China(Grant No.2024YFC3013200)the Shenzhen Peacock Plan(Grant No.QD2023006C).
文摘Submarine pipelines are critical infrastructures for offshore energy transport and communications. Understanding their structural response to near-field explosions is crucial for enhancing their blast resistance and operational safety. This study presents a computational study on the interaction between explosion-induced bubbles and a seabed-mounted pipeline. A recently developed computational framework is employed, which couples a compressible fluid solver with a finite element structural solver via a partitioned procedure. An embedded boundary method and a level-set method are employed to handle the fluid-structure and gas-liquid interfaces. Using this framework, we analyze the flow field evolution, bubble dynamics, and transient pipe deformation. Two distinct response modes are identified: periodic oscillation under low-pressure loading and downward collapse triggered by high-pressure loading and bubble jet impact. Specifically, under high-pressure conditions, the pipe initially deforms inward, generating a localized high-pressure zone within the concave region. During structural rebound, the trapped fluid is expelled upward, giving rise to a bubble jet. Further parametric studies on the pipe's internal pressure, wall thickness, and support angle reveal several key insights. A higher internal pressure delays structural collapse, and a greater pipe thickness results in more uniform implosion morphologies. The support angle strongly influences the collapse dynamics, with the shortest collapse time occurring at 60 °. These findings offer new insights for the protective design of submarine pipelines.
基金The Hainan Provincial Natural Science Foundation of China under contract No.322CXTD531the National Key Research and Development Program of China under contract Nos 2018YFC0310005,2016YFC0302504.
文摘Some deep-sea microbes may incorporate inorganic carbon to reduce CO_(2) emission to upper layer and atmosphere.How the microbial inhabitants can be affected under addition of bicarbonate has not been studied using in situ fixed and lysed samples.In this study,we cultivated 40 L natural bottom water at~1000 m depth with a final concentration of 0.1 mmol/L bicarbonate for 40 min and applied multiple in situ nucleic acids collection(MISNAC)apparatus for nucleic acids extraction from the cultivation.Our classification result of the cultivation sample showed a distinct microbial community structure,compared with the samples obtained by Niskin bottle and six working units of MISNAC.Except for notable enrichment of Alteromonas,we detected prevalence of Asprobacter,Ilumatobacter and Saccharimonadales in the cultivation.Deep-sea lineages of Euryarchaeota,SAR406,SAR202 and SAR324 were almost completely absent from the cultivation and Niskin samples.This study revealed the dominant microbes affected by bicarbonate addition and Niskin sampling,which suggested rapid responses of deep-sea microbes to the environmental changes.
基金financial support from China National Science Foundation(52306254)fundings from Shenzhen Science and Technology Program(GJHZ20220913143001002)are gratefully acknowledged+3 种基金financial support from Hainan International Science and Technology Cooperation Research and Development Project(GHYF2025017)Science and Technology Innovation Teams of Shanxi Province(202304051001012)Guangdong Pearl River Talent Program(2021QN02H836)Shenzhen Key Laboratory of Advanced Technology for Marine Ecology(ZDSYS20230626091459009).
文摘With the growing global focus on reducing greenhouse gas emissions,hydrate-based CO_(2) sequestration in marine sediments has gained wide attention due to its high storage capacity and thermodynamic stability of CO_(2) hydrate.However,the limited understanding of the CO_(2) hydrate stability zone,particularly in the presence of abundant swelling type clays,i.e.,Na-montmorillonite,warrants further investigation.This study examines the thermodynamic effects of Na-montmorillonite on the phase equilibria of CO_(2) hydrate under varying water contents(30-80 wt%).The results reveal that Na-montmorillonite inhibits CO_(2) hydrate formation thermodynamically with a significant inhibition effect as the water content decreases.A notable leftward shift of up to 2.7 K in the phase equilibrium temperature was observed at 3.90 MPa with 30 wt%water content.A thermodynamic model was developed integrating the diffuse double layer theory and Hu-Lee-Sum water activity correlation model into the classical Chen-Guo model.The proposed model demonstrated high accuracy with the measured data with an absolute average deviation of pressure below 0.5%.The thermodynamic inhibition effect is attributed to the decrease in water activity caused by the Na+exchange in the diffuse double layer on the clay surface.This study also presents the implication of swelling type clay on the CO_(2) hydrate stability zone in a permafrost setting,highlighting its impact on the CO_(2) storage site selection and CO_(2) storage capacity.These findings provide valuable insights for optimizing hydrate-based CO_(2) sequestration strategies,contributing to CO_(2) mitigation technology.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52271282,51909189 and 52277227)supported by the Open fund of Key Laboratory of Low-grade Energy Utilization Technologies and Systems,Ministry of Education of China,Chongqing University,(Grant No.LLEUTS-202410)+2 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010846)the Shenzhen Science and Technology Programme(Grant Nos.RCYX20231211090210018,WDZC20231125203917001)the Tsinghua Shenzhen International Graduate School via the Scientific Research Start-Up Funds(Grant No.QD2021023C).
文摘To enhance the efficiency of wind energy harvesters,aerodynamic modifications to bluff bodies prove highly effective.This study introduces two innovative galloping piezoelectric energy harvesters(GPEHs)equipped with two symmetrical splitters on a cuboid bluff body:GPEH with upstream splitters(GPEH-US)and GPEH with downstream splitters(GPEH-DS).Wind tunnel experiments evaluated the impact of splitter angle and length on energy harvesting performance across varying wind speeds.The results indicate that larger splitter angles and shorter lengths are more favorable for energy harvesting in GPEH-US.The optimal configuration,determined as GPEH-US with α=90°,L=0.4D,reduces the threshold wind speed,expands the effective wind speed range for energy harvesting,and increases maximum voltage and power output by over 99%,301%,respectively,compared with conventional GPEH.Conversely,GPEH-DS are less effective for energy harvesting but demonstrate potential in vibration control applications.Computational fluid dynamics(CFD)simulations using the OpenFOAM toolbox qualitatively elucidate the physical mechanisms driving these results.A larger splitter angle enables secondary small-scale vortices(SV)to absorb more energy,accelerates boundary layer separation,intensifies and disorderly vortex shedding,enhances aerodynamic instability,and improves energy harvesting performance.
基金supported by the National Natural Science Foundation China(Nos.61931015 and 61971257)the National Key R&D Program of China(Nos.2020YFD0901000 and 2017YFE0112300)+2 种基金Beijing National Research Center for Information Science and Technology(Nos.BNR2019RC01014 and BNR2019TD01001)the project of Peng Cheng Laboratory(No.LZC0020)the China Postdoctoral Science Foundation(Nos.2019T120091 and 2018M640130)。
文摘Recently,the fifth-generation(5G)of wireless networks mainly focuses on the terrestrial applications.However,the well-developed emerging technologies in 5G are hardly applied to the maritime communications,resulting from the lack of communication infrastructure deployed on the vast ocean,as well as different characteristics of wireless propagation environment over the sea and maritime user distribution.To satisfy the expected plethora of broadband communications and multimedia applications on the ocean,a brand-new maritime information network with a comprehensive coverage capacity in terms of all-hour,all-weather,and all-sea-area has been expected as a revolutionary paradigm to extend the terrestrial capacity of enhanced broadband,massive access,ultra-reliable,and low-latency to the vast ocean.Further considering the limited available resource of maritime communication infrastructure,the convergence of broadband and broadcast/multicast can be regarded as a possible yet practical solution for realizing an efficient and flexible resource configuration with high quality of services.Moreover,according to such multi-functionality and all-coverage maritime information network,the monitoring and sensing of vast ocean area relying on massive Ocean of Things and advanced radar techniques can be also supported.Concerning these issues above,this study proposes a Software Defined Networking(SDN)based Maritime Giant Cellular Network(MagicNet)architecture for broadband and multimedia services.Based on this network,the convergence techniques of broadband and broadcast/multicast,and their supporting for maritime monitoring and marine sensing are also introduced and surveyed.
基金National Natural Science Foundation of China(52070117)Research Projects from Shenzhen Municipal Science and Technology Innovation Council(WDZC20200819163549002,JCYJ20200109142822787)+1 种基金Guangdong Higher Education Institutions Innovative Research Team of Urban Water Cycle and Ecological Safety,China(2023KCXTD053)Shenzhen Science and Technology Program,China(ZDSYS20220606100806014).
文摘Harmful cyanobacterial blooms(HCBs)pose a global ecological threat.Ultraviolet C(UVC)irradiation at 254 nm is a promising method for controlling cyanobacterial proliferation,but the growth suppression is temporary.Resuscitation remains a challenge with UVC application,necessitating alternative strategies for lethal effects.Here,we show synergistic inhibition of Microcystis aeruginosa using ultraviolet A(UVA)pre-irradiation before UVC.We find that low-dosage UVA pre-irradiation(1.5 J cm^(−2))combined with UVC(0.085 J cm^(−2))reduces 85%more cell densities compared to UVC alone(0.085 J cm^(−2))and triggers mazEF-mediated regulated cell death(RCD),which led to cell lysis,while high-dosage UVA pre-irradiations(7.5 and 14.7 J cm^(−2))increase cell densities by 75-155%.Our oxygen evolution tests and transcriptomic analysis indicate that UVA pre-irradiation damages photosystem I(PSI)and,when combined with UVC-induced PSII damage,synergistically inhibits photosynthesis.However,higher UVA dosages activate the SOS response,facilitating the repair of UVC-induced DNA damage.This study highlights the impact of UVA pre-irradiation on UVC suppression of cyanobacteria and proposes a practical strategy for improved HCBs control.
基金This work was supported in part by National Natural Science Foundation of China(No.52007123)Guangdong Basic and Applied Basic Research Foundation for Offshore Wind(No.2022A1515240019).
文摘With the rapid expansion of offshore wind farms(OWFs)in remote regions,the study of highly reliable electrical collector systems(ECSs)has become increasingly important.Post-fault network recovery is considered as an effective mea-sure of reliability enhancement.In this paper,we propose a smart switch configuration that facilitates network recovery,making it well-suited for ECSs operating in harsh environ-ments.To accommodate the increased complexity of ECSs,a novel reliability assessment(RA)method considering detailed switch configuration is devised.This method effectively identi-fies the minimum outage propagation areas and incorporates post-fault network recovery strategies.The optimal normal op-erating state and network reconfiguration strategies that maxi-mize ECS reliability can be obtained after optimization.Case studies on real-life OwFs validate the effectiveness and superi-ority of the proposed RA method compared with the traditional sequential Monte-Carlo simulation method.Moreover,numeri-cal tests demonstrate that the proposed switch configuration,in conjunction with proper topology and network recovery,achieves the highest benefits across a wide range of operating conditions.
基金supported by the Institute for Ocean Engineering,Shenzhen International Graduate School,Tsinghua University.
文摘Atmospheric Kármán vortex streets,which frequently emerge on the leeward side of isolated islands under specific atmospheric conditions,play a critical role in large-scale atmospheric dynamics.However,their automated detection and the influence of atmospheric variables on their formation remain insufficiently explored.Here,we firstly developed an object detection dataset utilizing 20 years of cloud imagery from the MODIS aboard the Terra and Aqua satellites,facilitating the application of artificial intelligence algorithms for the automated detection of Kármán vortex streets.Given that these vortex streets can manifest under both cloudy and cloudfree conditions,we further assessed the contribution of various spectral bands to vortex detection by implying a multi-channel classification network.This network,built upon a custom-designed miniResNet dual-level classification network and trained on MODls HDFformat sensor data,demonstrates that the dataset is particularly suited for detecting Kármán vortex streets in cloudy conditions.Different types of advanced algorithms were applied on the dataset,yielding baseline performance metrics and potential detection methods.Additionally,we proposed two optimization strategies tailored to Kármán vortex streets detection.First,leveraging the intrinsic properties of vortex structures,we introduced a Gamma loss optimization for bounding box aspect ratios,which significantly enhanced performance across six YoLO-based models.Second,we investigated the role of atmospheric variables in vortex formation and incorporated an auxiliary-task-enhanced learning approach to further refine detection accuracy,drawing upon findings from our recently published work.In summary,this study provides a novel dataset that supports meteorological and climatological research,addressing a critical gap in atmospheric data.Furthermore,the proposed auxiliary optimization strategies highlight the distinct challenges of Kármán vortex streets detection compared to conventional object detection,underscoring the unique structural and atmospheric characteristics of these phenomena.
文摘Removing high-risk and persistent contaminants from water is challenging,because they typically exist at low concentrations in complex water matrices.Electrified flow-through technologies are viable to overcome the limitations induced by mass transport for efficient contaminant removal.Modifying the local environment of the flow-through electrodes offers opportunities to further improve the reaction kinetics and selectivity for achieving near-complete removal of these contaminants from water.Here,we present state-of-the-art local environment modification approaches that can be incorporated into electrified flow-through technologies to intensify water treatment.We first show methods of nanospace incorporation,local geometry adjustment,and microporous structure optimization that can induce spatial confinement,enhanced local electric field,and microperiodic vortex,respectively,for local environment modification.We then discuss why local environment modification can complement the flow-through electrodes for improving the reaction rate and selectivity.Finally,we outline appropriate scenarios of intensifying electrified flow-through technologies through local environment modification for fit-for-purpose water treatment applications.
