Disinfection of swimming pool water is critical to ensure the safety of the recreational activity for swimmers.However,swimming pools have a constant loading of organic matter from input water and anthropogenic contam...Disinfection of swimming pool water is critical to ensure the safety of the recreational activity for swimmers.However,swimming pools have a constant loading of organic matter from input water and anthropogenic contamination,leading to elevated levels of disinfection byproducts(DBPs).Epidemiological studies have associated increased risks of adverse health effects with frequent exposure to DBPs in swimming pools.Zhang et al.(2023b)investigated the occurrence of trihalomethanes(THMs),haloacetic acids(HAAs),haloacetonitriles(HANs),and haloacetaldehydes(HALs)in eight swimming pools and the corresponding input water in a city in Eastern China.The concentrations of THMs,HAAs,HANs,and HALs in swimming poolswere 1–2 orders of magnitude higher than those detected in the input water.The total lifetime cancer and non-cancer health risks of swimmers through oral,dermal,inhalation,buccal,and aural exposure pathways were assessed using the United States Environmental Protection Agency’s(USEPA)standard model and Swimmer Exposure Assessment Model(SWIMODEL).The results showed that dermal and inhalation pathways were the most significant for the associated cancer and non-cancer risks.This article provides an overview and perspectives of DBPs in swimming pools,the benefits of swimming,the need to improve the monitoring of DBPs,and the importance of swimmers’hygiene practices to keep swimming pools clean.The benefits of swimming outweigh the risks from DBP exposure for the promotion of public health.展开更多
Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently need...Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently needed as the foundation.Water,a key carrier in the carbon cycle,necessitates investigation into groundwater carbon pools’contribution to atmospheric carbon sinks.This study assessed carbon stocks in the Yinchuan Basin’s soil and groundwater carbon pools.Findings indicate the basin’s surface soils contain approximately 24.16 Tg of organic carbon and a total of 60.01 Tg of carbon.In contrast,the basin’s groundwater holds around 4.90 Tg of carbon,roughly one-fifth of the organic carbon in surface soils.Thus,groundwater and soil carbon pools possess comparable carbon stocks,underscoring the importance of the groundwater carbon pool.Studies on terrestrial carbon balance should incorporate groundwater carbon pools,which deserve increased focus.Evaluating groundwater carbon pools’contributions is vital for achieving the dual carbon goals.展开更多
There are three formation stages of Silurian hydrocarbon pools in the Tarim Basin. The widely distributed asphaltic sandstones in the Tazhong （central Tarim） and Tabei （northern Tarim） areas are the results of des...There are three formation stages of Silurian hydrocarbon pools in the Tarim Basin. The widely distributed asphaltic sandstones in the Tazhong （central Tarim） and Tabei （northern Tarim） areas are the results of destruction of hydrocarbon pools formed in the first-stage, and the asphaltic sandstones around the Awati Sag were formed in the second-stage. The hydrocarbon migration characteristics reflected by the residual dry asphalts could represent the migration characteristics of hydrocarbons in the Silurian paleo-pools, while the present movable oil in the Silurian reservoirs is related to the iater-stage （the third-stage） hydrocarbon accumulation.展开更多
The degradation of animal carcasses can lead to rapid waste release(e.g.,pathogenic bacteria,viruses,prions,or parasites)and also result in nutrient accumulation in the surrounding environment.However,how viral profil...The degradation of animal carcasses can lead to rapid waste release(e.g.,pathogenic bacteria,viruses,prions,or parasites)and also result in nutrient accumulation in the surrounding environment.However,how viral profile responds and influences nutrient pool(carbon(C),nitrogen(N),phosphorus(P)and sulfur(S))in polluted water caused by animal carcass decomposition had not been explored.Here,we combined metagenomic analysis,16S rRNA gene sequencing and water physicochemical assessment to explore the response of viral communities under different temperatures(23℃,26℃,29℃,32℃,and 35℃)in water polluted by cadaver,as well as compare the contribution of viral/bacterial communities on water nutrient pool.We found that a total of 15,240 viral species were classified and mainly consisted of Siphoviridae.Both temperature and carrion reduced the viral diversity and abundance.Only a small portion of the viruses(∼8.8%)had significant negative correlations with temperature,while most were not sensitive.Our results revealed that the viruses had lager contribution on nutrient pool than bacteria.Besides,viral-related functional genes involved in C,N,P and S cycling.These functional genes declined during carcass decomposition and covered part of the central nutrient cycle metabolism(including carbon sugar transformation,denitrification,P mineralization and extracelluar sulfate transfer,etc.).Our result implies that human regulation of virus communities may be more important than bacterial communities in regulating and managing polluted water quality and nutrition.展开更多
Paediatric liver transplantation(PLT)is a life-saving procedure for children with advanced liver disease or hepatoblastoma.The number of available grafts is limited in relation to the number of children on PLT waiting...Paediatric liver transplantation(PLT)is a life-saving procedure for children with advanced liver disease or hepatoblastoma.The number of available grafts is limited in relation to the number of children on PLT waiting list.This graft shortage has led transplant societies and healthcare organizations to explore ways to investigate possible options and expand the donor pool.The safe use of grafts from obese donors has always been a subject of debate among PLT specialists.Donors’obesity is strongly associated with hepatic steatosis which can affect graft function by impairing microcirculation and maximizing the potential of ischemiareperfusion injury.Donor body mass index consideration should go hand in hand with the workup for hepatic steatosis which is an independent predictor for early graft dysfunction.New strategies to optimize the grafts before PLT such as normothermic regional perfusion and ex vivo liver perfusion can potentially mitigate the risk of using grafts from obese donors.This review summarizes the available evidence about the impact of donor obesity on PLT and highlights the current policies to widen the graft pool and suggest future research directions to improve donor selection and patient outcomes.展开更多
Large-sized titanium alloy ingots produced by vacuum arc remelting(VAR)technology are susceptible to metallurgical imperfections such as compositional segregation,inconsistent solidification microstructures,black spot...Large-sized titanium alloy ingots produced by vacuum arc remelting(VAR)technology are susceptible to metallurgical imperfections such as compositional segregation,inconsistent solidification microstructures,black spots,and inclusions.These defects are intricately linked to the electromagnetic effects,temperature distribution,and fluid dynamics during the melting process.The self-induced magnetic field created by the electric current,along with the axial magnetic field applied to stabilize the arc,significantly influences the solidification of titanium alloy ingots.A mathematical model optimized for the integrated analysis of multiple fields—electromagnetic,fluid,and thermal—was developed for the VAR solidification process of titanium alloys.The influence mechanism of electromagnetic field on the macroscopic solidification process of titanium alloy was investigated.The findings indicate the presence of two competing forces within the VAR molten pool,namely,thermal buoyancy and the Lorentz force.Introducing a coupled self-induced magnetic field and elevating the current to 15 kA led to an increase in the molten pool depth by 42.9%and a reduction in the thickness of the mushy zone by 25.2%.The application of a constant axial magnetic field enhances a unidirectional momentum buildup within the molten pool,thereby enhancing the flow velocity and cooling efficiency of melt.展开更多
Edge deployment solutions based on convolutional neural networks(CNNs)have garnered significant attention because of their potential applications.However,traditional CNNs rely on pooling to reduce the feature size,lea...Edge deployment solutions based on convolutional neural networks(CNNs)have garnered significant attention because of their potential applications.However,traditional CNNs rely on pooling to reduce the feature size,leading to substantial information loss and reduced network robustness.Herein,we propose a more robust adaptive pooling network(APN)method implemented using memristor technology.Our method introduces an improved pooling layer that reduces input features to an arbitrary scale without compromising their importance.Different coupling coefficients of the pooling layer are stored as conductance values in arrays.We validate the proposed APN on generic datasets,demonstrating significant performance improvements over previously reported CNN architectures.Additionally,we evaluate the APN on a CAPTCHA recognition task with perturbations to assess network robustness.The results show that the APN achieves 92.6% accuracy in 4-digit CAPTCHA recognition and exhibits higher robustness.This brief presents a highly robust and novel scheme for edge computing using memristor technology.展开更多
In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the p...In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the production of parts and larger structures was investigated in detail.With different experimental setups in normal and microgravity,laser spots with diameters from 5 mm to 100 mm were realized to melt the regolith simulant EAC-1A and an 80%/20%mixture of TUBS-T and TUBS-M,which are used as a substitute for the actual lunar soil.In the experiments performed,the critical parameters are the size of the laser spot,the velocity of the laser spot on the surface of the powder bed,the gravity and the wettability of the powder bed by the melt.The stability of the melt pool as a function of these parameters was investigated and it was found that the formation of a stable melt pool is determined by gravity for large melt pool sizes in the range of 50 mm and by surface tension for small melt pool sizes in the range of a few mm.展开更多
The anisotropy of LPBF fabricated components is a serious concern and often increases the overall production cost by creating the necessity for secondary thermal homogenization processes.The microstructural features a...The anisotropy of LPBF fabricated components is a serious concern and often increases the overall production cost by creating the necessity for secondary thermal homogenization processes.The microstructural features are the main driving force behind these anisotropic behaviors.Whereas the unique and distinctive thermal history inside a melt pool and its transient transformation is the reason for the characteristic microstructural features of LPBF fabricated components.Therefore,this paper investigates the prominent thermal variables such as heating rate,cooling rate,solidification rate etc.,and their evolution inside the melt pool of 316 L stainless steel during LPBF process to provide a reference for further exploring the generation of various microstructural features.A numerical model for macroscale investigation of thermal behavior inside melt pool was established.A 3D Gaussian heat source model coupled with temperature and density dependent properties of powder and solid phase 316 L stainless steel was used.The variation and evolution of significant thermal variables inside the melt pool were then investigated with the established numerical model.The study found that the Gaussian profile of a laser beam influences the thermal variables inside a melt-pool,including cooling rates,solidification rates,and thermal gradients.The nodes lying under the laser edge receive less heat,resulting in higher cooling effects,which shapes the grain morphology.Finer grains can be formed near the bottom melt front as well as at the center of the melt-pool surface.However,reheating adjacent tracks can result in grain coarsening.Since the generation of microstructural features is dominantly dependent on the thermal behavior inside the melt pool,an assessment of these variables is important and provides basics for the understating of different features generated in the LPBF processed components.展开更多
Cold pools(CPs)significantly influence coastal heavy rainfall,but detailed observations of them are limited due to the lack of vertical measurement instruments.This study statistically characterizes CPs in the coastal...Cold pools(CPs)significantly influence coastal heavy rainfall,but detailed observations of them are limited due to the lack of vertical measurement instruments.This study statistically characterizes CPs in the coastal monsoon region of South China using unique data from the 356-m-high Shenzhen Meteorological Tower.CP occurrence correlates with convective activities influenced by the summer monsoon in the seasonal variations and land–sea breeze activities in the diurnal cycle.The CPs predominantly dry the atmosphere,highlighting the dominant role of dry entrainment through convective downdrafts in their formation,with a minor role of hydrometeor evaporation.The average CP depth is estimated at 668.0 m,deeper than tropical CPs but shallower than midlatitude counterparts.The CP properties exhibit diurnal variability,largely influenced by mesoscale convective system(MCS)activities.MCS-induced CPs are deeper and more intense than those from individual convective cells,while linear-MCS-produced CPs are the most intense.These observations from the coastal monsoon region contribute to a comprehensive global understanding of CP characteristics,complementing existing studies from midlatitude and tropical regions.展开更多
In modern engineering,enhancing boiling heat transfer efficiency is crucial for optimizing energy use and several industrial processes involving different types of materials.This study explores the enhancement of pool...In modern engineering,enhancing boiling heat transfer efficiency is crucial for optimizing energy use and several industrial processes involving different types of materials.This study explores the enhancement of pool boiling heat transfer potentially induced by combining perforated copper particles on a heated surface with a sodium dodecyl sulfate(SDS)surfactant in saturated deionized water.Experiments were conducted at standard atmospheric pressure,with heat flux ranging from 20 to 100 kW/m2.The heating surface,positioned below the layer of freely moving copper beads,allowed the particle layer to shift due to liquid convection and steam nucleation.The study reports on the influence of copper bead diameter(2,3,4,and 5 mm),particle quantity,arrangement,and SDS concentration(20,200,and 500 ppm).It is shown that the combination of 5 mm particles and a 500 ppm SDS concentration can yield a remarkable 139%improvement in heat transfer efficiency.As demonstrated by direct flow visualization,bubble formation occurs primarily in the gaps between the particles and the heated surface,with the presence of SDS reducing bubble size and accelerating bubble detachment.展开更多
Tree rings provide long-term records of tree growth and climate changes,which makes them ideal benchmarks for forest modeling.Tree-ring information has greatly improved the reliability of 3-PG,which is one of the most...Tree rings provide long-term records of tree growth and climate changes,which makes them ideal benchmarks for forest modeling.Tree-ring information has greatly improved the reliability of 3-PG,which is one of the most commonly used process-based forest growth models.Here,we strengthen 3-PG's ability to simulate tree-ring width and stable carbon isotopes(δ^(13)C)by enhancing its descriptions of tree physiology.The major upgrade was adding a carbon storage pool for tree-ring formation using stored carbohydrates.We also incorporated previous modifications(replacing the age modifier with a height modifier)of 3-PG and tested their efficacy in improving tree-ring simulations.We ran the model based on two grand fir(Abies grandis)stands.The updated model greatly improved the simulations for both tree-ring widths andδ^(13)C.The results represent one of the best tree-ringδ^(13)C simulations,which accurately captured the amplitude in annual variations ofδ^(13)C.The correlations(R^(2))between simulations and observations reached 0.50 and 0.73 at two stands,respectively.The new model also greatly improved the simulations of raw tree-ring widths and detrended ring-width index(RWI).Because of better descriptions of tree physiology and more accurate simulations of tree rings than the previous model version,the updated 3-PG should provide more reliable simulations than previous 3-PG versions when tree-ring information is used as a benchmark in future studies.展开更多
This study focuses on tool condition recognition through data-driven approaches to enhance the intelligence level of computerized numerical control(CNC)machining processes and improve tool utilization efficiency.Tradi...This study focuses on tool condition recognition through data-driven approaches to enhance the intelligence level of computerized numerical control(CNC)machining processes and improve tool utilization efficiency.Traditional tool monitoring methods that rely on empirical knowledge or limited mathematical models struggle to adapt to complex and dynamic machining environments.To address this,we implement real-time tool condition recognition by introducing deep learning technology.Aiming to the insufficient recognition accuracy,we propose a pyramid pooling-based vision Transformer network(P2ViT-Net)method for tool condition recognition.Using images as input effectively mitigates the issue of low-dimensional signal features.We enhance the vision Transformer(ViT)framework for image classification by developing the P2ViT model and adapt it to tool condition recognition.Experimental results demonstrate that our improved P2ViT model achieves 94.4%recognition accuracy,showing a 10%improvement over conventional ViT and outperforming all comparative convolutional neural network models.展开更多
With the rapid development of intelligent video surveillance technology,pedestrian re-identification has become increasingly important inmulti-camera surveillance systems.This technology plays a critical role in enhan...With the rapid development of intelligent video surveillance technology,pedestrian re-identification has become increasingly important inmulti-camera surveillance systems.This technology plays a critical role in enhancing public safety.However,traditional methods typically process images and text separately,applying upstream models directly to downstream tasks.This approach significantly increases the complexity ofmodel training and computational costs.Furthermore,the common class imbalance in existing training datasets limitsmodel performance improvement.To address these challenges,we propose an innovative framework named Person Re-ID Network Based on Visual Prompt Technology andMulti-Instance Negative Pooling(VPM-Net).First,we incorporate the Contrastive Language-Image Pre-training(CLIP)pre-trained model to accurately map visual and textual features into a unified embedding space,effectively mitigating inconsistencies in data distribution and the training process.To enhancemodel adaptability and generalization,we introduce an efficient and task-specific Visual Prompt Tuning(VPT)technique,which improves the model’s relevance to specific tasks.Additionally,we design two key modules:the Knowledge-Aware Network(KAN)and theMulti-Instance Negative Pooling(MINP)module.The KAN module significantly enhances the model’s understanding of complex scenarios through deep contextual semantic modeling.MINP module handles samples,effectively improving the model’s ability to distinguish fine-grained features.The experimental outcomes across diverse datasets underscore the remarkable performance of VPM-Net.These results vividly demonstrate the unique advantages and robust reliability of VPM-Net in fine-grained retrieval tasks.展开更多
With the rise in drowning accidents in swimming pools,the demand for the precision and speed in artificial intelligence(AI)drowning detection methods has become increasingly crucial.Here,an improved YOLO-based method,...With the rise in drowning accidents in swimming pools,the demand for the precision and speed in artificial intelligence(AI)drowning detection methods has become increasingly crucial.Here,an improved YOLO-based method,named DrownACB-YOLO,for drowning detection in swimming pools is proposed.Since existing methods focus on the drowned state,a transition label is added to the original dataset to provide timely alerts.Following this expanded dataset,two improvements are implemented in the original YOLOv5.Firstly,the spatial pyramid pooling(SPP)module and the default upsampling operator are replaced by the atrous spatial pyramid pooling(ASPP)module and the content-aware reassembly of feature(CARAFE)module,respectively.Secondly,the cross stage partial bottleneck with three convolutions(C3)module at the end of the backbone is replaced with the bottleneck transformer(BotNet)module.The results of comparison experiments demonstrate that DrownACB-YOLO performs better than other models.展开更多
To build a community of scientific innovation,serve the country’s goals of carbon peak and carbon neutrality,promote application of scientific research outcomes in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA),...To build a community of scientific innovation,serve the country’s goals of carbon peak and carbon neutrality,promote application of scientific research outcomes in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA),and accelerate the formation of new quality productive forces in the green energy industry,the Yangjiang Offshore Wind Power Laboratory and the GBA Institute of Industry and Talent(GBAIIT)recently signed a strategic cooperation agreement.展开更多
In order to obtain good welding quality, it is necessary to apply quality control because there are many influencing factors in laser welding process. The key to realize welding quality control is to obtain the qualit...In order to obtain good welding quality, it is necessary to apply quality control because there are many influencing factors in laser welding process. The key to realize welding quality control is to obtain the quality information. Abundant weld quality information is contained in weld pool and keyhole. Aiming at Nd：YAG laser welding of stainless steel, a coaxial visual sensing system was constructed. The images of weld pool and keyhole were obtained. Based on the gray character of weld pool and keyhole in images, an image processing algorithm was designed. The search start point and search criteria of weld pool and keyhole edge were determined respectively.展开更多
文摘Disinfection of swimming pool water is critical to ensure the safety of the recreational activity for swimmers.However,swimming pools have a constant loading of organic matter from input water and anthropogenic contamination,leading to elevated levels of disinfection byproducts(DBPs).Epidemiological studies have associated increased risks of adverse health effects with frequent exposure to DBPs in swimming pools.Zhang et al.(2023b)investigated the occurrence of trihalomethanes(THMs),haloacetic acids(HAAs),haloacetonitriles(HANs),and haloacetaldehydes(HALs)in eight swimming pools and the corresponding input water in a city in Eastern China.The concentrations of THMs,HAAs,HANs,and HALs in swimming poolswere 1–2 orders of magnitude higher than those detected in the input water.The total lifetime cancer and non-cancer health risks of swimmers through oral,dermal,inhalation,buccal,and aural exposure pathways were assessed using the United States Environmental Protection Agency’s(USEPA)standard model and Swimmer Exposure Assessment Model(SWIMODEL).The results showed that dermal and inhalation pathways were the most significant for the associated cancer and non-cancer risks.This article provides an overview and perspectives of DBPs in swimming pools,the benefits of swimming,the need to improve the monitoring of DBPs,and the importance of swimmers’hygiene practices to keep swimming pools clean.The benefits of swimming outweigh the risks from DBP exposure for the promotion of public health.
基金supported by the third scientific survey project in Xinjiang(2022xjkk0300)the public welfare geological survey projects initiated by the China Geological Survey(DD20190296,DD20221731).
文摘Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently needed as the foundation.Water,a key carrier in the carbon cycle,necessitates investigation into groundwater carbon pools’contribution to atmospheric carbon sinks.This study assessed carbon stocks in the Yinchuan Basin’s soil and groundwater carbon pools.Findings indicate the basin’s surface soils contain approximately 24.16 Tg of organic carbon and a total of 60.01 Tg of carbon.In contrast,the basin’s groundwater holds around 4.90 Tg of carbon,roughly one-fifth of the organic carbon in surface soils.Thus,groundwater and soil carbon pools possess comparable carbon stocks,underscoring the importance of the groundwater carbon pool.Studies on terrestrial carbon balance should incorporate groundwater carbon pools,which deserve increased focus.Evaluating groundwater carbon pools’contributions is vital for achieving the dual carbon goals.
文摘There are three formation stages of Silurian hydrocarbon pools in the Tarim Basin. The widely distributed asphaltic sandstones in the Tazhong （central Tarim） and Tabei （northern Tarim） areas are the results of destruction of hydrocarbon pools formed in the first-stage, and the asphaltic sandstones around the Awati Sag were formed in the second-stage. The hydrocarbon migration characteristics reflected by the residual dry asphalts could represent the migration characteristics of hydrocarbons in the Silurian paleo-pools, while the present movable oil in the Silurian reservoirs is related to the iater-stage （the third-stage） hydrocarbon accumulation.
基金supported by the National Natural Science Foundation of China (No.42007026)the Medical Innovation and Development Project of Lanzhou University (lzuyxcx-2022-172)
文摘The degradation of animal carcasses can lead to rapid waste release(e.g.,pathogenic bacteria,viruses,prions,or parasites)and also result in nutrient accumulation in the surrounding environment.However,how viral profile responds and influences nutrient pool(carbon(C),nitrogen(N),phosphorus(P)and sulfur(S))in polluted water caused by animal carcass decomposition had not been explored.Here,we combined metagenomic analysis,16S rRNA gene sequencing and water physicochemical assessment to explore the response of viral communities under different temperatures(23℃,26℃,29℃,32℃,and 35℃)in water polluted by cadaver,as well as compare the contribution of viral/bacterial communities on water nutrient pool.We found that a total of 15,240 viral species were classified and mainly consisted of Siphoviridae.Both temperature and carrion reduced the viral diversity and abundance.Only a small portion of the viruses(∼8.8%)had significant negative correlations with temperature,while most were not sensitive.Our results revealed that the viruses had lager contribution on nutrient pool than bacteria.Besides,viral-related functional genes involved in C,N,P and S cycling.These functional genes declined during carcass decomposition and covered part of the central nutrient cycle metabolism(including carbon sugar transformation,denitrification,P mineralization and extracelluar sulfate transfer,etc.).Our result implies that human regulation of virus communities may be more important than bacterial communities in regulating and managing polluted water quality and nutrition.
文摘Paediatric liver transplantation(PLT)is a life-saving procedure for children with advanced liver disease or hepatoblastoma.The number of available grafts is limited in relation to the number of children on PLT waiting list.This graft shortage has led transplant societies and healthcare organizations to explore ways to investigate possible options and expand the donor pool.The safe use of grafts from obese donors has always been a subject of debate among PLT specialists.Donors’obesity is strongly associated with hepatic steatosis which can affect graft function by impairing microcirculation and maximizing the potential of ischemiareperfusion injury.Donor body mass index consideration should go hand in hand with the workup for hepatic steatosis which is an independent predictor for early graft dysfunction.New strategies to optimize the grafts before PLT such as normothermic regional perfusion and ex vivo liver perfusion can potentially mitigate the risk of using grafts from obese donors.This review summarizes the available evidence about the impact of donor obesity on PLT and highlights the current policies to widen the graft pool and suggest future research directions to improve donor selection and patient outcomes.
基金financially supported by the National Natural Science Foundation of China(Nos.52422408 and 52171031)the Excellent Youth Fund of Liaoning Natural Science Foundation(No.2023JH3/10200001)the Liaoning Xingliao Talents-Top-notch Young Talents Project(No.XLYC2203064).
文摘Large-sized titanium alloy ingots produced by vacuum arc remelting(VAR)technology are susceptible to metallurgical imperfections such as compositional segregation,inconsistent solidification microstructures,black spots,and inclusions.These defects are intricately linked to the electromagnetic effects,temperature distribution,and fluid dynamics during the melting process.The self-induced magnetic field created by the electric current,along with the axial magnetic field applied to stabilize the arc,significantly influences the solidification of titanium alloy ingots.A mathematical model optimized for the integrated analysis of multiple fields—electromagnetic,fluid,and thermal—was developed for the VAR solidification process of titanium alloys.The influence mechanism of electromagnetic field on the macroscopic solidification process of titanium alloy was investigated.The findings indicate the presence of two competing forces within the VAR molten pool,namely,thermal buoyancy and the Lorentz force.Introducing a coupled self-induced magnetic field and elevating the current to 15 kA led to an increase in the molten pool depth by 42.9%and a reduction in the thickness of the mushy zone by 25.2%.The application of a constant axial magnetic field enhances a unidirectional momentum buildup within the molten pool,thereby enhancing the flow velocity and cooling efficiency of melt.
基金supported by the National Natural Science Foundation of China(Grant Nos.62274002,62304001,and 62201005)the Anhui Provincial Natural Science Foundation(Grant Nos.2308085QF213 and 2408085QF211)the Natural Science Research Project of the Anhui Educational Committee(Grant No.2023AH050072)。
文摘Edge deployment solutions based on convolutional neural networks(CNNs)have garnered significant attention because of their potential applications.However,traditional CNNs rely on pooling to reduce the feature size,leading to substantial information loss and reduced network robustness.Herein,we propose a more robust adaptive pooling network(APN)method implemented using memristor technology.Our method introduces an improved pooling layer that reduces input features to an arbitrary scale without compromising their importance.Different coupling coefficients of the pooling layer are stored as conductance values in arrays.We validate the proposed APN on generic datasets,demonstrating significant performance improvements over previously reported CNN architectures.Additionally,we evaluate the APN on a CAPTCHA recognition task with perturbations to assess network robustness.The results show that the APN achieves 92.6% accuracy in 4-digit CAPTCHA recognition and exhibits higher robustness.This brief presents a highly robust and novel scheme for edge computing using memristor technology.
基金supported by 40th DLR Parabolic Flight Campaign and within the project"Powder based Additive Manufacturing at reduced Gravitation"(Grant No.FKZ:50WM2068)European Space Agency,OSIP Off-Earth Manufacturing and Construction Campaign(Grant No.4000134280/21/NL/GLC/mk)。
文摘In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the production of parts and larger structures was investigated in detail.With different experimental setups in normal and microgravity,laser spots with diameters from 5 mm to 100 mm were realized to melt the regolith simulant EAC-1A and an 80%/20%mixture of TUBS-T and TUBS-M,which are used as a substitute for the actual lunar soil.In the experiments performed,the critical parameters are the size of the laser spot,the velocity of the laser spot on the surface of the powder bed,the gravity and the wettability of the powder bed by the melt.The stability of the melt pool as a function of these parameters was investigated and it was found that the formation of a stable melt pool is determined by gravity for large melt pool sizes in the range of 50 mm and by surface tension for small melt pool sizes in the range of a few mm.
文摘The anisotropy of LPBF fabricated components is a serious concern and often increases the overall production cost by creating the necessity for secondary thermal homogenization processes.The microstructural features are the main driving force behind these anisotropic behaviors.Whereas the unique and distinctive thermal history inside a melt pool and its transient transformation is the reason for the characteristic microstructural features of LPBF fabricated components.Therefore,this paper investigates the prominent thermal variables such as heating rate,cooling rate,solidification rate etc.,and their evolution inside the melt pool of 316 L stainless steel during LPBF process to provide a reference for further exploring the generation of various microstructural features.A numerical model for macroscale investigation of thermal behavior inside melt pool was established.A 3D Gaussian heat source model coupled with temperature and density dependent properties of powder and solid phase 316 L stainless steel was used.The variation and evolution of significant thermal variables inside the melt pool were then investigated with the established numerical model.The study found that the Gaussian profile of a laser beam influences the thermal variables inside a melt-pool,including cooling rates,solidification rates,and thermal gradients.The nodes lying under the laser edge receive less heat,resulting in higher cooling effects,which shapes the grain morphology.Finer grains can be formed near the bottom melt front as well as at the center of the melt-pool surface.However,reheating adjacent tracks can result in grain coarsening.Since the generation of microstructural features is dominantly dependent on the thermal behavior inside the melt pool,an assessment of these variables is important and provides basics for the understating of different features generated in the LPBF processed components.
基金supported by the National Key Research and Development Program of China (Grant No. 2024YFC3013003)the National Natural Science Foundation of China (Grant No. 42475002)+2 种基金the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant Nos. SML2024SP035, SML2024SP012, and 311024001)the Guangdong Basic and Applied Basic Research Foundation (Grant Nos. 2025A1515011974, 2024A1515510005 and 2020B0301030004)the Key Innovation Team of China Meteorological Administration (Grant No. CMA2023ZD08)
文摘Cold pools(CPs)significantly influence coastal heavy rainfall,but detailed observations of them are limited due to the lack of vertical measurement instruments.This study statistically characterizes CPs in the coastal monsoon region of South China using unique data from the 356-m-high Shenzhen Meteorological Tower.CP occurrence correlates with convective activities influenced by the summer monsoon in the seasonal variations and land–sea breeze activities in the diurnal cycle.The CPs predominantly dry the atmosphere,highlighting the dominant role of dry entrainment through convective downdrafts in their formation,with a minor role of hydrometeor evaporation.The average CP depth is estimated at 668.0 m,deeper than tropical CPs but shallower than midlatitude counterparts.The CP properties exhibit diurnal variability,largely influenced by mesoscale convective system(MCS)activities.MCS-induced CPs are deeper and more intense than those from individual convective cells,while linear-MCS-produced CPs are the most intense.These observations from the coastal monsoon region contribute to a comprehensive global understanding of CP characteristics,complementing existing studies from midlatitude and tropical regions.
基金supported by the National Natural Science Foundation of China(Project No.52166004)the National Key Research and Development Program of China(Project No.2022YFC3902000)+2 种基金the Major Science and Technology Special Project of Yunnan Province(Project Nos.202202AG050007202202AG050002)the Research on the Development of Complete Sets of Technology for Extraction of Aromatic Substances from Tobacco Waste and Its Application,Applied Research-Pyrolysis Process Technology Research(2023QT01).
文摘In modern engineering,enhancing boiling heat transfer efficiency is crucial for optimizing energy use and several industrial processes involving different types of materials.This study explores the enhancement of pool boiling heat transfer potentially induced by combining perforated copper particles on a heated surface with a sodium dodecyl sulfate(SDS)surfactant in saturated deionized water.Experiments were conducted at standard atmospheric pressure,with heat flux ranging from 20 to 100 kW/m2.The heating surface,positioned below the layer of freely moving copper beads,allowed the particle layer to shift due to liquid convection and steam nucleation.The study reports on the influence of copper bead diameter(2,3,4,and 5 mm),particle quantity,arrangement,and SDS concentration(20,200,and 500 ppm).It is shown that the combination of 5 mm particles and a 500 ppm SDS concentration can yield a remarkable 139%improvement in heat transfer efficiency.As demonstrated by direct flow visualization,bubble formation occurs primarily in the gaps between the particles and the heated surface,with the presence of SDS reducing bubble size and accelerating bubble detachment.
基金supported by the National Natural Science Foundation of China(Nos.42271048,42430503,and 31971492).
文摘Tree rings provide long-term records of tree growth and climate changes,which makes them ideal benchmarks for forest modeling.Tree-ring information has greatly improved the reliability of 3-PG,which is one of the most commonly used process-based forest growth models.Here,we strengthen 3-PG's ability to simulate tree-ring width and stable carbon isotopes(δ^(13)C)by enhancing its descriptions of tree physiology.The major upgrade was adding a carbon storage pool for tree-ring formation using stored carbohydrates.We also incorporated previous modifications(replacing the age modifier with a height modifier)of 3-PG and tested their efficacy in improving tree-ring simulations.We ran the model based on two grand fir(Abies grandis)stands.The updated model greatly improved the simulations for both tree-ring widths andδ^(13)C.The results represent one of the best tree-ringδ^(13)C simulations,which accurately captured the amplitude in annual variations ofδ^(13)C.The correlations(R^(2))between simulations and observations reached 0.50 and 0.73 at two stands,respectively.The new model also greatly improved the simulations of raw tree-ring widths and detrended ring-width index(RWI).Because of better descriptions of tree physiology and more accurate simulations of tree rings than the previous model version,the updated 3-PG should provide more reliable simulations than previous 3-PG versions when tree-ring information is used as a benchmark in future studies.
基金supported by China Postdoctoral Science Foundation(No.2024M754122)the Postdoctoral Fellowship Programof CPSF(No.GZB20240972)+3 种基金the Jiangsu Funding Program for Excellent Postdoctoral Talent(No.2024ZB194)Natural Science Foundation of Jiangsu Province(No.BK20241389)Basic Science ResearchFund of China(No.JCKY2023203C026)2024 Jiangsu Province Talent Programme Qinglan Project.
文摘This study focuses on tool condition recognition through data-driven approaches to enhance the intelligence level of computerized numerical control(CNC)machining processes and improve tool utilization efficiency.Traditional tool monitoring methods that rely on empirical knowledge or limited mathematical models struggle to adapt to complex and dynamic machining environments.To address this,we implement real-time tool condition recognition by introducing deep learning technology.Aiming to the insufficient recognition accuracy,we propose a pyramid pooling-based vision Transformer network(P2ViT-Net)method for tool condition recognition.Using images as input effectively mitigates the issue of low-dimensional signal features.We enhance the vision Transformer(ViT)framework for image classification by developing the P2ViT model and adapt it to tool condition recognition.Experimental results demonstrate that our improved P2ViT model achieves 94.4%recognition accuracy,showing a 10%improvement over conventional ViT and outperforming all comparative convolutional neural network models.
基金funded by the Key Research and Development Program of Hubei Province,China(Grant No.2023BEB024)the Young and Middle-aged Scientific and Technological Innova-tion Team Plan in Higher Education Institutions inHubei Province,China(GrantNo.T2023007)the key projects ofHubei Provincial Department of Education(No.D20161403).
文摘With the rapid development of intelligent video surveillance technology,pedestrian re-identification has become increasingly important inmulti-camera surveillance systems.This technology plays a critical role in enhancing public safety.However,traditional methods typically process images and text separately,applying upstream models directly to downstream tasks.This approach significantly increases the complexity ofmodel training and computational costs.Furthermore,the common class imbalance in existing training datasets limitsmodel performance improvement.To address these challenges,we propose an innovative framework named Person Re-ID Network Based on Visual Prompt Technology andMulti-Instance Negative Pooling(VPM-Net).First,we incorporate the Contrastive Language-Image Pre-training(CLIP)pre-trained model to accurately map visual and textual features into a unified embedding space,effectively mitigating inconsistencies in data distribution and the training process.To enhancemodel adaptability and generalization,we introduce an efficient and task-specific Visual Prompt Tuning(VPT)technique,which improves the model’s relevance to specific tasks.Additionally,we design two key modules:the Knowledge-Aware Network(KAN)and theMulti-Instance Negative Pooling(MINP)module.The KAN module significantly enhances the model’s understanding of complex scenarios through deep contextual semantic modeling.MINP module handles samples,effectively improving the model’s ability to distinguish fine-grained features.The experimental outcomes across diverse datasets underscore the remarkable performance of VPM-Net.These results vividly demonstrate the unique advantages and robust reliability of VPM-Net in fine-grained retrieval tasks.
文摘With the rise in drowning accidents in swimming pools,the demand for the precision and speed in artificial intelligence(AI)drowning detection methods has become increasingly crucial.Here,an improved YOLO-based method,named DrownACB-YOLO,for drowning detection in swimming pools is proposed.Since existing methods focus on the drowned state,a transition label is added to the original dataset to provide timely alerts.Following this expanded dataset,two improvements are implemented in the original YOLOv5.Firstly,the spatial pyramid pooling(SPP)module and the default upsampling operator are replaced by the atrous spatial pyramid pooling(ASPP)module and the content-aware reassembly of feature(CARAFE)module,respectively.Secondly,the cross stage partial bottleneck with three convolutions(C3)module at the end of the backbone is replaced with the bottleneck transformer(BotNet)module.The results of comparison experiments demonstrate that DrownACB-YOLO performs better than other models.
文摘To build a community of scientific innovation,serve the country’s goals of carbon peak and carbon neutrality,promote application of scientific research outcomes in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA),and accelerate the formation of new quality productive forces in the green energy industry,the Yangjiang Offshore Wind Power Laboratory and the GBA Institute of Industry and Talent(GBAIIT)recently signed a strategic cooperation agreement.
基金Project (10776020) supported by the Joint Foundation of the National Natural Science Foundation of China and China Academy of Engineering Physics
文摘In order to obtain good welding quality, it is necessary to apply quality control because there are many influencing factors in laser welding process. The key to realize welding quality control is to obtain the quality information. Abundant weld quality information is contained in weld pool and keyhole. Aiming at Nd：YAG laser welding of stainless steel, a coaxial visual sensing system was constructed. The images of weld pool and keyhole were obtained. Based on the gray character of weld pool and keyhole in images, an image processing algorithm was designed. The search start point and search criteria of weld pool and keyhole edge were determined respectively.
