风场预报是智能网格预报的重要支撑,提高风场预报准确率,能够为风能预报提供核心保障。在综合评估2023年汛期CMA-MESO 3 km(China Meteorological Administration Mesoscale Model at 3 km resolution)模式在山西逐小时10 m风预报能力...风场预报是智能网格预报的重要支撑,提高风场预报准确率,能够为风能预报提供核心保障。在综合评估2023年汛期CMA-MESO 3 km(China Meteorological Administration Mesoscale Model at 3 km resolution)模式在山西逐小时10 m风预报能力的基础上,基于自适应Kalman滤波方法,开展针对纬向风(U)、经向风(V)的客观订正,以期建立适应山西复杂地形特征的客观预报方案,促进国产模式本地化业务应用。结果表明:①全风速预报偏大,预报误差呈“单峰型”日变化,峰值出现在18:00-20:00,正偏差主要位于忻定和太原盆地以及山西南部。②U、V预报误差与预报值呈显著正相关,需考虑不同强度预报风速误差随时效变化的特征,避免订正不足或过订正。③Kalman滤波方案(KM)订正幅度小且不稳定,订正后均方根误差R MSE削减不足6%,准确率提升不足2%。④基于动态分级的改进方案(CBKM)突破KM订正瓶颈,更准确地估计系统误差并有效订正,更好再现不同地区风速日变化,平均误差M E趋近0,R MSE削减32.8%,风向、风速预报准确率分别提升8.29%、7.92%,峰值时刻订正率达83.49%。展开更多
For the diagnostics and health management of lithium-ion batteries,numerous models have been developed to understand their degradation characteristics.These models typically fall into two categories:data-driven models...For the diagnostics and health management of lithium-ion batteries,numerous models have been developed to understand their degradation characteristics.These models typically fall into two categories:data-driven models and physical models,each offering unique advantages but also facing limitations.Physics-informed neural networks(PINNs)provide a robust framework to integrate data-driven models with physical principles,ensuring consistency with underlying physics while enabling generalization across diverse operational conditions.This study introduces a PINN-based approach to reconstruct open circuit voltage(OCV)curves and estimate key ageing parameters at both the cell and electrode levels.These parameters include available capacity,electrode capacities,and lithium inventory capacity.The proposed method integrates OCV reconstruction models as functional components into convolutional neural networks(CNNs)and is validated using a public dataset.The results reveal that the estimated ageing parameters closely align with those obtained through offline OCV tests,with errors in reconstructed OCV curves remaining within 15 mV.This demonstrates the ability of the method to deliver fast and accurate degradation diagnostics at the electrode level,advancing the potential for precise and efficient battery health management.展开更多
Computed tomography is an indispensable X-ray imaging modality used to diagnose numerous pathologies, but it can also involve the delivery of high ionizing radiation doses harmful to the health of patients. This study...Computed tomography is an indispensable X-ray imaging modality used to diagnose numerous pathologies, but it can also involve the delivery of high ionizing radiation doses harmful to the health of patients. This study aims to survey the level of radiation doses delivered to child patients during head exams in CT imaging to set up the Dosimetric Reference Levels (DRLs), a routine dose optimization tool, based on data acquired at the University Hospital of Angré (UHA), the University Hospital of Treichville (UHT) and the Polyclinic Hospital Farah (Farah) for optimizing procedures in Ivorian hospitals. Prospectively performed on 334 CT images of 186 child patients, this study was carried out on CT systems such as Hitachi Scenaria, Sinovision Insitum, and Philips Incisive used respectively at UHA, UHT and Farah. Children’s scan data were classified into four age bands: vol or dose-length product as DLP) value, whatever the hospital, increases with respect to the age of child patients. Based on the 75th percentile of the whole dose distributions, the DRLs of the CTDIvol is 54.37 mGy whatever the age groups and those of the DLP with respect to age bands are 1224.55 mGy∙cm, 1414.06 mGy∙cm, 1632.24 mGy.cm and 1544.57 mGy∙cm, respectively. The averaged values of CTDIvol and DLP smaller than the corresponding DRLs values suggest that practices in our three facilities are optimized. However, comparing our results with those from different international studies, we see that the CTDIvol and DLP values obtained in the present work are higher. These results suggest additional surveys to ensure our DRLs values and efforts from radiologists, imaging technicians and medical physicists to strengthen clinical procedures for the radiation protection of children undergoing CT scans in Côte d’Ivoire.展开更多
Metallogenic research on structural levels can reveal vertical patterns of mineralization and facilitate the deep exploration of economic minerals.However,research focusing on the correlation between structural levels...Metallogenic research on structural levels can reveal vertical patterns of mineralization and facilitate the deep exploration of economic minerals.However,research focusing on the correlation between structural levels and mineralization remains limited.In this study,we summarize the deformation patterns and associated mineral deposits observed at different crustal levels(i.e.,surface,shallow,middle,and deep structural levels,corresponding to depths of<2,2-8,8-15,and>15 km,respectively).Furthermore,we examine the genetic association between structural levels and metallogenesis,demonstrating that distinct structural levels are linked to specific types of mineralization.Key factors that vary across crustal levels include temperature,pressure,and fluid circulation.Ore-forming processes involve interactions between structures and fluids under varying temperatures and pressures.Structural levels influence mineralization by controlling the temperatures,pressures,and deformation mechanisms that drive the activation,migration,and enrichment of ore-forming materials.展开更多
BackgroundIt's crucial to study the effect of changes in thresholds(T)and most comfortable levels(M)on behavioral measurements in young children using cochlear implants.This would help the clinician with the optim...BackgroundIt's crucial to study the effect of changes in thresholds(T)and most comfortable levels(M)on behavioral measurements in young children using cochlear implants.This would help the clinician with the optimization and validation of programming parameters.ObjectiveThe study has attempted to describe the changes in behavioral responses with modification of T and M levels.MethodsTwenty-five participants in the age range 5 to 12 years using HR90K/HiFocus1J or HR90KAdvantage/HiFocus1J with Harmony speech processors participated in the study.A decrease in T levels,a rise in T levels,or a decrease in M levels in the everyday program were used to create experimental programs.Sound field thresholds and speech perception were measured at 50 dBHL for three experimental and everyday programs.ConclusionThe results indicated that only reductions of M levels resulted in significantly(p<0.01)poor aided thresholds and speech perception.On the other hand,variation in T levels did not have significant changes in either sound field thresholds or speech perception.The results highlight that M levels must be correctly established in order to prevent decreased speech perception and audibility.展开更多
The purpose of this research was to evaluate radiological safety in pediatric radiology in hospitals in the Kongo Central province of the DRC. To this end, we surveyed a convenience sample of 50 health professionals, ...The purpose of this research was to evaluate radiological safety in pediatric radiology in hospitals in the Kongo Central province of the DRC. To this end, we surveyed a convenience sample of 50 health professionals, including 10 radiologists working in the hospitals covered by the survey, to assess the practice of pediatric radiology and the degree of compliance with radiation protection principles for the safety of children and the environment. We collected radiophysical parameters to calculate entrance doses in pediatric radiology in radiology departments to determine the dosimetric level by comparison with the diagnostic reference levels of the International Commission on Radiological Protection (ICRP). All in all, we found that in Kongo Central in the DRC, many health personnel surveyed reported that more than 30% of requested radiological examinations are not justified. Also, after comparing the entrance doses produced in the surveyed departments with those of the International Commission on Radiological Protection (ICRP), a statistically significant difference was found in pediatric radiology between the average doses in five out of six surveyed departments and those of the ICRP. Therefore, almost all of the surveyed departments were found to be highly irradiating in children, while excessive X-ray irradiation in children can have significant effects due to their increased sensitivity to radiation. Among the risks are: increased cancer risks, damage to developing cells, potential genetic effects, and neurological effects. This is why support for implementing radiation protection principles is a necessity to promote the safety of patients and the environment against the harmful effects of X-rays in conventional radiology.展开更多
The Thwaites Glacier in western Antarctica(Fig. 1) keeps glaciologists and climate scientists awake at night. The 120 kmwide glacier loses about 45 billion tonnes of ice each year, accounting for about 4% of global se...The Thwaites Glacier in western Antarctica(Fig. 1) keeps glaciologists and climate scientists awake at night. The 120 kmwide glacier loses about 45 billion tonnes of ice each year, accounting for about 4% of global sea level rise [1]. If it melted completely, sea levels would climb 65 cm, and follow-on effects could lead to a 3 m increase [2]. But if some scientists' vision becomes reality, in 10–15 years construction crews will sail into the Amundsen Sea off Antarctica to begin building an 80 km long underwater curtain that will shield the glacier from the warm currents that are accelerating its decline [3].展开更多
Water level is the overriding control on carbon cycles in peatlands,which are important for global carbon cycles and ecosystem services.To date,our knowledge of the pattern of water level fluctuations in peatlands and...Water level is the overriding control on carbon cycles in peatlands,which are important for global carbon cycles and ecosystem services.To date,our knowledge of the pattern of water level fluctuations in peatlands and the influence of precipitation and air temperature on them in the subtropical remains poor.In this study,we conducted continuous high-resolution monitoring of water levels from 2014 to 2021 in the Dajiuhu peatland,a typically subtropical peatland in central China.Monitoring results showed that the water level had strong annual(370 days) and seasonal(130 days) oscillations in the Dajiuhu peatland.The annual oscillation is associated with both precipitation and temperature,while the seasonal oscillation is mainly controlled by precipitation.In addition,the depth of peat surface to the water table(DWT) has weak but significant correlations with precipitation and temperature on the daily and weekly scales(r = 0.1–0.21,p<0.01).Once replacing DWT with water table fluctuation cumulation,the correlation coefficients increase apparently(r = 0.47–0.69,p<0.01),especially on the monthly scale.These findings highlight a more important role of the fluctuation than the mean position of water level and have the potential to improve the interpretation of water-level related paleoenvironmental proxies and the understanding of the relationship between water level and biogeochemical processes.展开更多
0 INTRODUTION The Kuqa Depression,situated along the northern margin of the Tarim Basin,holds substantial geological significance due to its intricate sedimentary burial history,tectonic history,and the evolution of h...0 INTRODUTION The Kuqa Depression,situated along the northern margin of the Tarim Basin,holds substantial geological significance due to its intricate sedimentary burial history,tectonic history,and the evolution of hydrocarbon source rocks(Jiang et al.,2024;Zhang et al.,2023;Huang et al.,2019;Yang et al.,2017;Jia et al.,2003;Hendrix,2000).展开更多
Separation between water and land is vital for marine scientific research and coastal zone planning and management.The contrasting backscatter properties of land and ocean enable clear water edge line identification i...Separation between water and land is vital for marine scientific research and coastal zone planning and management.The contrasting backscatter properties of land and ocean enable clear water edge line identification in synthetic aperture radar(SAR)imagery.However,SAR images are prone to speckle noise,and the complexity of the water-land boundaries environment makes accurate water-land separation challenging.To overcome noise and complex background interference in remote sensing images,an improved level set method was employed to enhance water-land separation.In the traditional distance regularized level set method,the selection of the image correlation weight coefficient and the edge indicator function directly influences the accuracy of the final segmentation results.A novel level set segmentation algorithm incorporating an improved edge indicator function is proposed to efficiently and accurately separate the water edge lines in SAR images.The distance regularized level set evolution model is enhanced by incorporating the signed pressure force function as an adaptive parameter,which serves as an external constraint for curve evolution.A novel level set model with an adaptive edge indicator function,combining gradient and regional information,is proposed.Experimental results demonstrate that the proposed model enhances the accuracy of waterland separation in SAR images.However,further research is needed to evaluate its potential for detecting boundaries in diverse marine environments and across different types of SAR imagery.展开更多
A cylindrical chamber with a rotating bottom holds significant potential for application in cell culture bioreactors due to its ability to generate more stable swirling flows.In order to control vortex breakdown withi...A cylindrical chamber with a rotating bottom holds significant potential for application in cell culture bioreactors due to its ability to generate more stable swirling flows.In order to control vortex breakdown within the chamber,this study first establishes a computational fluid dynamics simulation coupled with the level set method.Verified by experimental results in literature,this method accurately simulates the position and shape of vortex breakdown,and also predicts the critical Reynolds numbers for the appearance and detachment of vortex breakdown bubbles from the center.Additionally,it precisely captures the gas-liquid interface and depicts the vortex breakdown phenomenon in the air above the liquid for the first time.Finally,it predicts the impact of physical property of gas-liquid systems on vortex breakdown in response to significant changes in viscosity of microbial process systems.展开更多
A data-driven model ofmultiple variable cutting(M-VCUT)level set-based substructure is proposed for the topology optimization of lattice structures.TheM-VCUTlevel setmethod is used to represent substructures,enriching...A data-driven model ofmultiple variable cutting(M-VCUT)level set-based substructure is proposed for the topology optimization of lattice structures.TheM-VCUTlevel setmethod is used to represent substructures,enriching their diversity of configuration while ensuring connectivity.To construct the data-driven model of substructure,a database is prepared by sampling the space of substructures spanned by several substructure prototypes.Then,for each substructure in this database,the stiffness matrix is condensed so that its degrees of freedomare reduced.Thereafter,the data-drivenmodel of substructures is constructed through interpolationwith compactly supported radial basis function(CS-RBF).The inputs of the data-driven model are the design variables of topology optimization,and the outputs are the condensed stiffness matrix and volume of substructures.During the optimization,this data-driven model is used,thus avoiding repeated static condensation that would requiremuch computation time.Several numerical examples are provided to verify the proposed method.展开更多
The optimization of hole transport layer(HTL)is crucial for achieving high efficiency and stability in inverted perovskite solar cells(PSCs)due to its role in facilitating hole transport and passivating the perovskite...The optimization of hole transport layer(HTL)is crucial for achieving high efficiency and stability in inverted perovskite solar cells(PSCs)due to its role in facilitating hole transport and passivating the perovskite bottom interface.While self-assembled monolayers(SAMs)are commonly used for this purpose,the inherent limitations of a single SAM,such as fixed energy levels and rigid structure,restrict their adaptability for different perovskite components and further efficiency enhancement.Here,we demonstrate a stepwise deposition method for SAM-based HTLs to address this issue.We regulated the energy level gradient by depositing two SAMs with distinct energy levels,while the interactions between the phosphate groups in the SAMs and perovskite effectively reduce defect density at the bottom interface of the perovskite film.The as-fabricated PSCs achieved enhanced efficiency and stability with PCEs of 25.7% and 24.0% for rigid and flexible PSCs,respectively;these devices maintain 90% of their initial PCE after 500 h of maximum power point tracking,and retain 98% of their initial PCE after 4,000 bending cycles,representing one of the most stable flexible PSCs reported to date.展开更多
The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and ...The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and promising solution to these issues[3].However,the practical implementation of CO_(2)photoreduction is constrained by low efficiency,primarily due to the rapid recombination of photogenerated electron-hole pairs[4].展开更多
文摘风场预报是智能网格预报的重要支撑,提高风场预报准确率,能够为风能预报提供核心保障。在综合评估2023年汛期CMA-MESO 3 km(China Meteorological Administration Mesoscale Model at 3 km resolution)模式在山西逐小时10 m风预报能力的基础上,基于自适应Kalman滤波方法,开展针对纬向风(U)、经向风(V)的客观订正,以期建立适应山西复杂地形特征的客观预报方案,促进国产模式本地化业务应用。结果表明:①全风速预报偏大,预报误差呈“单峰型”日变化,峰值出现在18:00-20:00,正偏差主要位于忻定和太原盆地以及山西南部。②U、V预报误差与预报值呈显著正相关,需考虑不同强度预报风速误差随时效变化的特征,避免订正不足或过订正。③Kalman滤波方案(KM)订正幅度小且不稳定,订正后均方根误差R MSE削减不足6%,准确率提升不足2%。④基于动态分级的改进方案(CBKM)突破KM订正瓶颈,更准确地估计系统误差并有效订正,更好再现不同地区风速日变化,平均误差M E趋近0,R MSE削减32.8%,风向、风速预报准确率分别提升8.29%、7.92%,峰值时刻订正率达83.49%。
基金supported by the Beijing Natural Science Foundation(Grant No.L223013)。
文摘For the diagnostics and health management of lithium-ion batteries,numerous models have been developed to understand their degradation characteristics.These models typically fall into two categories:data-driven models and physical models,each offering unique advantages but also facing limitations.Physics-informed neural networks(PINNs)provide a robust framework to integrate data-driven models with physical principles,ensuring consistency with underlying physics while enabling generalization across diverse operational conditions.This study introduces a PINN-based approach to reconstruct open circuit voltage(OCV)curves and estimate key ageing parameters at both the cell and electrode levels.These parameters include available capacity,electrode capacities,and lithium inventory capacity.The proposed method integrates OCV reconstruction models as functional components into convolutional neural networks(CNNs)and is validated using a public dataset.The results reveal that the estimated ageing parameters closely align with those obtained through offline OCV tests,with errors in reconstructed OCV curves remaining within 15 mV.This demonstrates the ability of the method to deliver fast and accurate degradation diagnostics at the electrode level,advancing the potential for precise and efficient battery health management.
文摘Computed tomography is an indispensable X-ray imaging modality used to diagnose numerous pathologies, but it can also involve the delivery of high ionizing radiation doses harmful to the health of patients. This study aims to survey the level of radiation doses delivered to child patients during head exams in CT imaging to set up the Dosimetric Reference Levels (DRLs), a routine dose optimization tool, based on data acquired at the University Hospital of Angré (UHA), the University Hospital of Treichville (UHT) and the Polyclinic Hospital Farah (Farah) for optimizing procedures in Ivorian hospitals. Prospectively performed on 334 CT images of 186 child patients, this study was carried out on CT systems such as Hitachi Scenaria, Sinovision Insitum, and Philips Incisive used respectively at UHA, UHT and Farah. Children’s scan data were classified into four age bands: vol or dose-length product as DLP) value, whatever the hospital, increases with respect to the age of child patients. Based on the 75th percentile of the whole dose distributions, the DRLs of the CTDIvol is 54.37 mGy whatever the age groups and those of the DLP with respect to age bands are 1224.55 mGy∙cm, 1414.06 mGy∙cm, 1632.24 mGy.cm and 1544.57 mGy∙cm, respectively. The averaged values of CTDIvol and DLP smaller than the corresponding DRLs values suggest that practices in our three facilities are optimized. However, comparing our results with those from different international studies, we see that the CTDIvol and DLP values obtained in the present work are higher. These results suggest additional surveys to ensure our DRLs values and efforts from radiologists, imaging technicians and medical physicists to strengthen clinical procedures for the radiation protection of children undergoing CT scans in Côte d’Ivoire.
基金supported by National Key Research and Development Program of China(Grant Nos.2022YFF0800903 and 2024YFC2909905)the National Natural Science Foundation of China(NSFC)(Grant Nos.42261144669,42262026,and 42273073).
文摘Metallogenic research on structural levels can reveal vertical patterns of mineralization and facilitate the deep exploration of economic minerals.However,research focusing on the correlation between structural levels and mineralization remains limited.In this study,we summarize the deformation patterns and associated mineral deposits observed at different crustal levels(i.e.,surface,shallow,middle,and deep structural levels,corresponding to depths of<2,2-8,8-15,and>15 km,respectively).Furthermore,we examine the genetic association between structural levels and metallogenesis,demonstrating that distinct structural levels are linked to specific types of mineralization.Key factors that vary across crustal levels include temperature,pressure,and fluid circulation.Ore-forming processes involve interactions between structures and fluids under varying temperatures and pressures.Structural levels influence mineralization by controlling the temperatures,pressures,and deformation mechanisms that drive the activation,migration,and enrichment of ore-forming materials.
文摘BackgroundIt's crucial to study the effect of changes in thresholds(T)and most comfortable levels(M)on behavioral measurements in young children using cochlear implants.This would help the clinician with the optimization and validation of programming parameters.ObjectiveThe study has attempted to describe the changes in behavioral responses with modification of T and M levels.MethodsTwenty-five participants in the age range 5 to 12 years using HR90K/HiFocus1J or HR90KAdvantage/HiFocus1J with Harmony speech processors participated in the study.A decrease in T levels,a rise in T levels,or a decrease in M levels in the everyday program were used to create experimental programs.Sound field thresholds and speech perception were measured at 50 dBHL for three experimental and everyday programs.ConclusionThe results indicated that only reductions of M levels resulted in significantly(p<0.01)poor aided thresholds and speech perception.On the other hand,variation in T levels did not have significant changes in either sound field thresholds or speech perception.The results highlight that M levels must be correctly established in order to prevent decreased speech perception and audibility.
文摘The purpose of this research was to evaluate radiological safety in pediatric radiology in hospitals in the Kongo Central province of the DRC. To this end, we surveyed a convenience sample of 50 health professionals, including 10 radiologists working in the hospitals covered by the survey, to assess the practice of pediatric radiology and the degree of compliance with radiation protection principles for the safety of children and the environment. We collected radiophysical parameters to calculate entrance doses in pediatric radiology in radiology departments to determine the dosimetric level by comparison with the diagnostic reference levels of the International Commission on Radiological Protection (ICRP). All in all, we found that in Kongo Central in the DRC, many health personnel surveyed reported that more than 30% of requested radiological examinations are not justified. Also, after comparing the entrance doses produced in the surveyed departments with those of the International Commission on Radiological Protection (ICRP), a statistically significant difference was found in pediatric radiology between the average doses in five out of six surveyed departments and those of the ICRP. Therefore, almost all of the surveyed departments were found to be highly irradiating in children, while excessive X-ray irradiation in children can have significant effects due to their increased sensitivity to radiation. Among the risks are: increased cancer risks, damage to developing cells, potential genetic effects, and neurological effects. This is why support for implementing radiation protection principles is a necessity to promote the safety of patients and the environment against the harmful effects of X-rays in conventional radiology.
文摘The Thwaites Glacier in western Antarctica(Fig. 1) keeps glaciologists and climate scientists awake at night. The 120 kmwide glacier loses about 45 billion tonnes of ice each year, accounting for about 4% of global sea level rise [1]. If it melted completely, sea levels would climb 65 cm, and follow-on effects could lead to a 3 m increase [2]. But if some scientists' vision becomes reality, in 10–15 years construction crews will sail into the Amundsen Sea off Antarctica to begin building an 80 km long underwater curtain that will shield the glacier from the warm currents that are accelerating its decline [3].
基金supported by the National Natural Science Foundation of China(No.U20A2094)。
文摘Water level is the overriding control on carbon cycles in peatlands,which are important for global carbon cycles and ecosystem services.To date,our knowledge of the pattern of water level fluctuations in peatlands and the influence of precipitation and air temperature on them in the subtropical remains poor.In this study,we conducted continuous high-resolution monitoring of water levels from 2014 to 2021 in the Dajiuhu peatland,a typically subtropical peatland in central China.Monitoring results showed that the water level had strong annual(370 days) and seasonal(130 days) oscillations in the Dajiuhu peatland.The annual oscillation is associated with both precipitation and temperature,while the seasonal oscillation is mainly controlled by precipitation.In addition,the depth of peat surface to the water table(DWT) has weak but significant correlations with precipitation and temperature on the daily and weekly scales(r = 0.1–0.21,p<0.01).Once replacing DWT with water table fluctuation cumulation,the correlation coefficients increase apparently(r = 0.47–0.69,p<0.01),especially on the monthly scale.These findings highlight a more important role of the fluctuation than the mean position of water level and have the potential to improve the interpretation of water-level related paleoenvironmental proxies and the understanding of the relationship between water level and biogeochemical processes.
基金supported by the National Key Research and Development Project(No.2019YFA0708601)the National Natural Science Foundation of China(No.4231101056)the Chinese Academy of Geological Sciences Basic Research Fund(No.JKYZD202402)。
文摘0 INTRODUTION The Kuqa Depression,situated along the northern margin of the Tarim Basin,holds substantial geological significance due to its intricate sedimentary burial history,tectonic history,and the evolution of hydrocarbon source rocks(Jiang et al.,2024;Zhang et al.,2023;Huang et al.,2019;Yang et al.,2017;Jia et al.,2003;Hendrix,2000).
基金The National Natural Science Foundation of China under contract Nos 61701416 and 61901195Natural Science Foundation of Jiangsu Province of China under contract No.BK20211341China Postdoctoral Science Foundation under contract No.2022M712687.
文摘Separation between water and land is vital for marine scientific research and coastal zone planning and management.The contrasting backscatter properties of land and ocean enable clear water edge line identification in synthetic aperture radar(SAR)imagery.However,SAR images are prone to speckle noise,and the complexity of the water-land boundaries environment makes accurate water-land separation challenging.To overcome noise and complex background interference in remote sensing images,an improved level set method was employed to enhance water-land separation.In the traditional distance regularized level set method,the selection of the image correlation weight coefficient and the edge indicator function directly influences the accuracy of the final segmentation results.A novel level set segmentation algorithm incorporating an improved edge indicator function is proposed to efficiently and accurately separate the water edge lines in SAR images.The distance regularized level set evolution model is enhanced by incorporating the signed pressure force function as an adaptive parameter,which serves as an external constraint for curve evolution.A novel level set model with an adaptive edge indicator function,combining gradient and regional information,is proposed.Experimental results demonstrate that the proposed model enhances the accuracy of waterland separation in SAR images.However,further research is needed to evaluate its potential for detecting boundaries in diverse marine environments and across different types of SAR imagery.
基金National Natural Science Foundation of China(22178228,22178326)
文摘A cylindrical chamber with a rotating bottom holds significant potential for application in cell culture bioreactors due to its ability to generate more stable swirling flows.In order to control vortex breakdown within the chamber,this study first establishes a computational fluid dynamics simulation coupled with the level set method.Verified by experimental results in literature,this method accurately simulates the position and shape of vortex breakdown,and also predicts the critical Reynolds numbers for the appearance and detachment of vortex breakdown bubbles from the center.Additionally,it precisely captures the gas-liquid interface and depicts the vortex breakdown phenomenon in the air above the liquid for the first time.Finally,it predicts the impact of physical property of gas-liquid systems on vortex breakdown in response to significant changes in viscosity of microbial process systems.
基金supported by the National Natural Science Foundation of China(Grant No.12272144).
文摘A data-driven model ofmultiple variable cutting(M-VCUT)level set-based substructure is proposed for the topology optimization of lattice structures.TheM-VCUTlevel setmethod is used to represent substructures,enriching their diversity of configuration while ensuring connectivity.To construct the data-driven model of substructure,a database is prepared by sampling the space of substructures spanned by several substructure prototypes.Then,for each substructure in this database,the stiffness matrix is condensed so that its degrees of freedomare reduced.Thereafter,the data-drivenmodel of substructures is constructed through interpolationwith compactly supported radial basis function(CS-RBF).The inputs of the data-driven model are the design variables of topology optimization,and the outputs are the condensed stiffness matrix and volume of substructures.During the optimization,this data-driven model is used,thus avoiding repeated static condensation that would requiremuch computation time.Several numerical examples are provided to verify the proposed method.
基金supported by the National Natural Science Foundation of China(22305119,12204234)the Natural Science Foundation of Jiangsu Province(BK20220878)+3 种基金the Fundamental Research Funds for the Central Universities(NS2023059)the China Postdoctoral Science Foundation(2022TQ0157,2023M741695)the Liaoning University Talent Introduction Research Startup Project(d295000048)the Center for Microscopy and Analysis of Nanjing University of Aeronautics and Astronautics for characterization support。
文摘The optimization of hole transport layer(HTL)is crucial for achieving high efficiency and stability in inverted perovskite solar cells(PSCs)due to its role in facilitating hole transport and passivating the perovskite bottom interface.While self-assembled monolayers(SAMs)are commonly used for this purpose,the inherent limitations of a single SAM,such as fixed energy levels and rigid structure,restrict their adaptability for different perovskite components and further efficiency enhancement.Here,we demonstrate a stepwise deposition method for SAM-based HTLs to address this issue.We regulated the energy level gradient by depositing two SAMs with distinct energy levels,while the interactions between the phosphate groups in the SAMs and perovskite effectively reduce defect density at the bottom interface of the perovskite film.The as-fabricated PSCs achieved enhanced efficiency and stability with PCEs of 25.7% and 24.0% for rigid and flexible PSCs,respectively;these devices maintain 90% of their initial PCE after 500 h of maximum power point tracking,and retain 98% of their initial PCE after 4,000 bending cycles,representing one of the most stable flexible PSCs reported to date.
文摘The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and promising solution to these issues[3].However,the practical implementation of CO_(2)photoreduction is constrained by low efficiency,primarily due to the rapid recombination of photogenerated electron-hole pairs[4].
