An approach called hybrid heat-source solid-state additive manufacturing (HHSAM) for fabricating multilayer AA6061 deposition with superior properties is proposed in this paper. As compared with the traditional additi...An approach called hybrid heat-source solid-state additive manufacturing (HHSAM) for fabricating multilayer AA6061 deposition with superior properties is proposed in this paper. As compared with the traditional additive friction stir deposition (AFSD), the auxiliary induction heat-source in HHSAM effectively improves the temperature and fluidity of plastic flow, which facilitates the formation and enrichment of residual Mg_(2)Si phases besides Al(Fe,Mn)Si, promotes the dynamic recrystallization and increases the bonding strength between layers during the deposition process. Therefore, the HHSAM depositions possess a more uniform structure, superior integral mechanical properties and corrosion resistance after heat treatment process. Moreover, HHSAMed specimens avoid abnormal grain growth (AGG) in heat treatment process, which is regularly encountered in the traditional AFSD. HHSAM method is proved to be a new solid-state additive manufacturing method with good developing prospects for fabricating alloy production with excellent properties in a high-efficiency manner.展开更多
The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower ...The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower crane in the Ma’anshan Yangtze River(MYR)Bridge site is analyzed in this paper.First,the membership function model that represents fuzzy comfortability is introduced in the probability density evolution method(PDEM).Second,based on Fechner’s law,the membership function curves are constructed according to three acceleration thresholds in ISO 2631.Then,the fuzzy comfortability for the super-high tower crane under stochastic wind loads is assessed on the basis of different cut-set levelsλ.Results show that the comfortability is over 0.9 under the required maximum operating wind velocity.The low sensitivity toλcan be observed in the reliability curves of ISOⅡandⅢmembership functions.The reliability of the ISOⅠmembership function is not sensitive toλwhenλ<0.7,whereas it becomes sensitive toλwhenλ>0.7.展开更多
Transmission towers,serving as the support structure of transmission lines,are significant for the functional-ity of an electric transmission system.Bolt joint loosening is one of the critical factors that can affect ...Transmission towers,serving as the support structure of transmission lines,are significant for the functional-ity of an electric transmission system.Bolt joint loosening is one of the critical factors that can affect the safety and stability of transmission towers.In this study,the effects of bolt joint loosening on the dynamic characteristics of a 220-kV angle steel transmission tower are the main topic of concern.First,the mechanical properties of typical joints subjected to different degrees of bolt loosening are studied by finite solid-element simulation,based on which a finite hybrid-element modeling method is developed for a tower structure suffering varying loose degrees in the joints.Taking a 220-kV angle steel transmission tower as the object,the influence of the position and degree of loosening on the tower’s natural frequencies and mode shapes are simulated and discussed.The results demonstrate that the main-member splice joint and the main diagonal-horizontal member gusset plate joint account for the dominant impact on the dynamic characteristics of the tower.In addition,the dominant joint shifts from the main-member splice joint to the main diagonal-horizontal member gusset plate joint as the considered modal order increases.In the case of double joints loosening simultaneously,the loosening of nondomi-nant joints has nonnegligible effects on the tower as well.展开更多
The efficient implementation of the Advanced Encryption Standard(AES)is crucial for network data security.This paper presents novel hardware implementations of the AES S-box,a core component,using tower field represen...The efficient implementation of the Advanced Encryption Standard(AES)is crucial for network data security.This paper presents novel hardware implementations of the AES S-box,a core component,using tower field representations and Boolean Satisfiability(SAT)solvers.Our research makes several significant contri-butions to the field.Firstly,we have optimized the GF(24)inversion,achieving a remarkable 31.35%area reduction(15.33 GE)compared to the best known implementations.Secondly,we have enhanced multiplication implementa-tions for transformation matrices using a SAT-method based on local solutions.This approach has yielded notable improvements,such as a 22.22%reduction in area(42.00 GE)for the top transformation matrix in GF((24)2)-type S-box implementation.Furthermore,we have proposed new implementations of GF(((22)2)2)-type and GF((24)2)-type S-boxes,with the GF(((22)2)2)-type demonstrating superior performance.This implementation offers two variants:a small area variant that sets new area records,and a fast variant that establishes new benchmarks in Area-Execution-Time(AET)and energy consumption.Our approach significantly improves upon existing S-box implementations,offering advancements in area,speed,and energy consumption.These optimizations contribute to more efficient and secure AES implementations,potentially enhancing various cryptographic applications in the field of network security.展开更多
This study explores the use of the Global Navigation Satellite System(GNSS)precise point positioning(PPP)technology to determine the natural vibration periods of towering structures through simulations and field testi...This study explores the use of the Global Navigation Satellite System(GNSS)precise point positioning(PPP)technology to determine the natural vibration periods of towering structures through simulations and field testing.During the simulation phase,a GNSS receiver captured vi-bration waveforms generated by a single-axis motion simulator based on preset signal parameters,analyzing how different satellite system configurations affect the efficiency of extracting vibration parameters.Subsequently,field tests were conducted on a high-rise steel singletube tower.The results indicate that in the simulation environment,no matter the PPP positioning data under single GPS or multisystem combination,the vibration frequency of singleaxis motion simulator can be accurately extracted after frequency do-main analysis,with multisystem setups providing more precise amplitude parameters.In the field test,the natural vibration periods of the main vibration modes of high-rise steel single-tube tower measured by PPP technology closely match the results of the first two modes derived from finite element analysis.The first mode period calculated by the em-pirical formula is approximately 6%higher than those determined through finite element analysis and PPP.This study demonstrates the potential of PPP for structural vibration analysis,offering significant benefits for assessing dynamic responses and monitoring the health of towering structures.展开更多
The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial ro...The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial role in unraveling the complexities of urban air pollution,atmospheric processes,and climate change in Beijing,China.This review paper provides a comprehensive overview of the measurements on the tower over the past two decades.Through long-term comprehensive observations,researchers have elucidated the intricate relationships between anthropogenic emissions,meteorological dynamics,and atmospheric composition,shedding light on the drivers of air pollution and its impacts on public health.The vertical measurements on the tower also enable detailed investigations into boundary layer dynamics,turbulent mixing,and pollutant dispersion,providing invaluable data for validating chemical transport models.Key findings from the tower’s research include the identification of positive feedback mechanisms between aerosols and the boundary layer,the characterization of pollutant sources and transport pathways,the determination of fluxes of gaseous and particulate species,and the assessment of the effectiveness of pollution control measures.Additionally,isotopic measurements have provided new insights into the sources and formation processes of particulate matter and reactive nitrogen species.Finally,the paper outlines future directions for tower-based research,emphasizing the need for long-term comprehensive measurements,the development of innovative tower platforms,and integration of emerging technologies.展开更多
The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly ...The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly favorable due to its retrofit viability.This review analyzes advancements in chemical absorption technologies specific to shipborne applications,focusing on absorbent development,absorption tower optimization,and system integration.This article begins with an overview of OCC principles and advantages,followed by a discussion of technological progress,including feasibility studies and project outcomes.It explores various chemical absorbents,assessing performance,degradation,and emissions.The structural configurations of absorption towers and their modeling techniques are examined,alongside challenges such as limited vessel space,energy constraints,and gas-liquid distribution inefficiencies.Future directions emphasize the need for innovative absorbent designs,advanced simulation for tower optimization,and enhanced integration with ship energy systems,including renewable energy and waste heat recovery.The potential for intelligent technologies to enable real-time monitoring and automated management of carbon capture systems is highlighted.Finally,further investigations into fundamental interfaces and reaction kinetics are essential for advancing shipborne carbon capture technologies,providing a crucial reference for researchers and practitioners in the field.展开更多
To address the challenges of multi-scale differences,complex background interference,and unstable small target positioning in visual inspection of power towers,the existing methods still face issues such as insufficie...To address the challenges of multi-scale differences,complex background interference,and unstable small target positioning in visual inspection of power towers,the existing methods still face issues such as insufficient feature interaction and unstable confidence estimation,which lead to performance degradation in complex backgrounds and occlusion conditions.This paper proposes a precise inspection method for key power tower components using autonomous drone positioning.To this end,this paper makes three key improvements to the you only look once version 11(YOLOv11)framework.First,it constructs C3k2-adaptive multi-receptive field block(C3k2-AMRB),combining multiple dilated convolutions with a reparameterization mechanism to significantly expand the receptive field and enhance multi-scale feature extraction.Second,it designs a hierarchical wavelet interaction unit(HWIU),which leverages high-and low-frequency decomposition and reconstruction of wavelet transform(WT)to achieve cross-scale semantic alignment,enhancing feature discriminability in complex backgrounds.Third,it proposes a distribution-aware confidence refinement head(DACR-Head),which adaptively calibrates classification confidence based on the statistical characteristics of the predicted bounding-box corner distribution,improving the localization stability and accuracy of small targets.Experiments on the inspection of power line assets dataset(InsPLAD)dataset show that the integrated approach achieves a component detection accuracy at intersection over union(IoU)=0.5(CDA_(50))of 88.3%and a component detection robustness(CDR_(50:95))of 69.8%,respectively,improvements of 4.4%and 7.0%over the baseline.展开更多
[Objective] This study aimed to investigate the adsorption properties of the adsorption tower filled with calcium superphosphate on ammonia volatilized with aer- ation. [Method] Adsorption tower filled with calcium su...[Objective] This study aimed to investigate the adsorption properties of the adsorption tower filled with calcium superphosphate on ammonia volatilized with aer- ation. [Method] Adsorption tower filled with calcium superphosphate was adopted as experimental apparatus, which was constructed by poly vinyl chloride （PVC） circular tubes. With hartshorn as the source of ammonia volatilization, the effect of different ratios of height to diameter of the tower filled with equal amount of calcium super-phosphate on ammonia adsorption was investigated. In addition, adsorption tower with height-diameter ratio of 9.9 was selected to adsorb the ammonia emitted from the composting systems of pig manure and chicken manure with optimized and reg- ulated carbon-nitrogen ratio. [Result] Under certain volatilization rate, calcium super- phosphate particles in the adsorption tower could effectively adsorb the ammonia, and the adsorption efficiency was enhanced with the increase of height-diameter ra-tio, which could reach above 90% with height-diameter ratio of more than 1.1; the ammonia emitted from composting systems of pig manure and chicken manure with optimized and regulated carbon-nitrogen ratio could be completely absorbed using adsorption tower with height-diameter ratio of 9.9 filled with calcium superphosphate accounting for about 8% of the weight of composting materials. [Conclusion] Experi- mental results of this study provided reference for the application of adsorption tower filled with calcium superphosphate in the treatment of waste gas emitted from com- posting materials.展开更多
"Problem of Towers of Hanoi",用递归的方法能很容易地解决问题,不用递归的方法将会是比较困难,因为随着参与盘子数的不断增多,计算时间和复杂度将会不断增多。运用仿真软件能清晰地勾勒出每个盘子的移动轨迹并给出详细的移..."Problem of Towers of Hanoi",用递归的方法能很容易地解决问题,不用递归的方法将会是比较困难,因为随着参与盘子数的不断增多,计算时间和复杂度将会不断增多。运用仿真软件能清晰地勾勒出每个盘子的移动轨迹并给出详细的移动步骤,这将会使此问题能更形象、更直观的解决。展开更多
基金supported by the Science and Technology Development Fund(FDCT)of Macao SAR(No.0110/2023/AMJ)Innovation Support Plan,Hong Kong,Macao and Taiwan Science and Technology Cooperation Project of Jiangsu Province(No.BZ2022047)+1 种基金National Key Research and Development Program of China(2023YFE0205300)the Joint Fund of Ba-sic and Applied Basic Research Fund of Guangdong Province(No.2021B1515130009).
文摘An approach called hybrid heat-source solid-state additive manufacturing (HHSAM) for fabricating multilayer AA6061 deposition with superior properties is proposed in this paper. As compared with the traditional additive friction stir deposition (AFSD), the auxiliary induction heat-source in HHSAM effectively improves the temperature and fluidity of plastic flow, which facilitates the formation and enrichment of residual Mg_(2)Si phases besides Al(Fe,Mn)Si, promotes the dynamic recrystallization and increases the bonding strength between layers during the deposition process. Therefore, the HHSAM depositions possess a more uniform structure, superior integral mechanical properties and corrosion resistance after heat treatment process. Moreover, HHSAMed specimens avoid abnormal grain growth (AGG) in heat treatment process, which is regularly encountered in the traditional AFSD. HHSAM method is proved to be a new solid-state additive manufacturing method with good developing prospects for fabricating alloy production with excellent properties in a high-efficiency manner.
基金The National Natural Science Foundation of China(No.52108274,52208481,52338011)State Scholarship Fund of China Scholarship Council(No.202306090285).
文摘The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower crane in the Ma’anshan Yangtze River(MYR)Bridge site is analyzed in this paper.First,the membership function model that represents fuzzy comfortability is introduced in the probability density evolution method(PDEM).Second,based on Fechner’s law,the membership function curves are constructed according to three acceleration thresholds in ISO 2631.Then,the fuzzy comfortability for the super-high tower crane under stochastic wind loads is assessed on the basis of different cut-set levelsλ.Results show that the comfortability is over 0.9 under the required maximum operating wind velocity.The low sensitivity toλcan be observed in the reliability curves of ISOⅡandⅢmembership functions.The reliability of the ISOⅠmembership function is not sensitive toλwhenλ<0.7,whereas it becomes sensitive toλwhenλ>0.7.
基金The Youth Foundation Project of Jiangsu Province(No.BK20230337)the Natural Science Research of Jiangsu Higher Education Institutions of China(No.22KJB560004)the National Natu-ral Science Foundation of China(No.52278523)。
文摘Transmission towers,serving as the support structure of transmission lines,are significant for the functional-ity of an electric transmission system.Bolt joint loosening is one of the critical factors that can affect the safety and stability of transmission towers.In this study,the effects of bolt joint loosening on the dynamic characteristics of a 220-kV angle steel transmission tower are the main topic of concern.First,the mechanical properties of typical joints subjected to different degrees of bolt loosening are studied by finite solid-element simulation,based on which a finite hybrid-element modeling method is developed for a tower structure suffering varying loose degrees in the joints.Taking a 220-kV angle steel transmission tower as the object,the influence of the position and degree of loosening on the tower’s natural frequencies and mode shapes are simulated and discussed.The results demonstrate that the main-member splice joint and the main diagonal-horizontal member gusset plate joint account for the dominant impact on the dynamic characteristics of the tower.In addition,the dominant joint shifts from the main-member splice joint to the main diagonal-horizontal member gusset plate joint as the considered modal order increases.In the case of double joints loosening simultaneously,the loosening of nondomi-nant joints has nonnegligible effects on the tower as well.
基金supported in part by the National Natural Science Foundation of China(No.62162016)in part by the Innovation Project of Guangxi Graduate Education(Nos.YCBZ2023132 and YCSW2023304).
文摘The efficient implementation of the Advanced Encryption Standard(AES)is crucial for network data security.This paper presents novel hardware implementations of the AES S-box,a core component,using tower field representations and Boolean Satisfiability(SAT)solvers.Our research makes several significant contri-butions to the field.Firstly,we have optimized the GF(24)inversion,achieving a remarkable 31.35%area reduction(15.33 GE)compared to the best known implementations.Secondly,we have enhanced multiplication implementa-tions for transformation matrices using a SAT-method based on local solutions.This approach has yielded notable improvements,such as a 22.22%reduction in area(42.00 GE)for the top transformation matrix in GF((24)2)-type S-box implementation.Furthermore,we have proposed new implementations of GF(((22)2)2)-type and GF((24)2)-type S-boxes,with the GF(((22)2)2)-type demonstrating superior performance.This implementation offers two variants:a small area variant that sets new area records,and a fast variant that establishes new benchmarks in Area-Execution-Time(AET)and energy consumption.Our approach significantly improves upon existing S-box implementations,offering advancements in area,speed,and energy consumption.These optimizations contribute to more efficient and secure AES implementations,potentially enhancing various cryptographic applications in the field of network security.
基金The National Natural Science Foundation of China(No.41974214).
文摘This study explores the use of the Global Navigation Satellite System(GNSS)precise point positioning(PPP)technology to determine the natural vibration periods of towering structures through simulations and field testing.During the simulation phase,a GNSS receiver captured vi-bration waveforms generated by a single-axis motion simulator based on preset signal parameters,analyzing how different satellite system configurations affect the efficiency of extracting vibration parameters.Subsequently,field tests were conducted on a high-rise steel singletube tower.The results indicate that in the simulation environment,no matter the PPP positioning data under single GPS or multisystem combination,the vibration frequency of singleaxis motion simulator can be accurately extracted after frequency do-main analysis,with multisystem setups providing more precise amplitude parameters.In the field test,the natural vibration periods of the main vibration modes of high-rise steel single-tube tower measured by PPP technology closely match the results of the first two modes derived from finite element analysis.The first mode period calculated by the em-pirical formula is approximately 6%higher than those determined through finite element analysis and PPP.This study demonstrates the potential of PPP for structural vibration analysis,offering significant benefits for assessing dynamic responses and monitoring the health of towering structures.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0760200)the National Natural Science Foundation of China(Grant Nos.42330605 and 42377101).
文摘The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial role in unraveling the complexities of urban air pollution,atmospheric processes,and climate change in Beijing,China.This review paper provides a comprehensive overview of the measurements on the tower over the past two decades.Through long-term comprehensive observations,researchers have elucidated the intricate relationships between anthropogenic emissions,meteorological dynamics,and atmospheric composition,shedding light on the drivers of air pollution and its impacts on public health.The vertical measurements on the tower also enable detailed investigations into boundary layer dynamics,turbulent mixing,and pollutant dispersion,providing invaluable data for validating chemical transport models.Key findings from the tower’s research include the identification of positive feedback mechanisms between aerosols and the boundary layer,the characterization of pollutant sources and transport pathways,the determination of fluxes of gaseous and particulate species,and the assessment of the effectiveness of pollution control measures.Additionally,isotopic measurements have provided new insights into the sources and formation processes of particulate matter and reactive nitrogen species.Finally,the paper outlines future directions for tower-based research,emphasizing the need for long-term comprehensive measurements,the development of innovative tower platforms,and integration of emerging technologies.
基金supported by the National Natural Science Foundation of China(51876118)。
文摘The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly favorable due to its retrofit viability.This review analyzes advancements in chemical absorption technologies specific to shipborne applications,focusing on absorbent development,absorption tower optimization,and system integration.This article begins with an overview of OCC principles and advantages,followed by a discussion of technological progress,including feasibility studies and project outcomes.It explores various chemical absorbents,assessing performance,degradation,and emissions.The structural configurations of absorption towers and their modeling techniques are examined,alongside challenges such as limited vessel space,energy constraints,and gas-liquid distribution inefficiencies.Future directions emphasize the need for innovative absorbent designs,advanced simulation for tower optimization,and enhanced integration with ship energy systems,including renewable energy and waste heat recovery.The potential for intelligent technologies to enable real-time monitoring and automated management of carbon capture systems is highlighted.Finally,further investigations into fundamental interfaces and reaction kinetics are essential for advancing shipborne carbon capture technologies,providing a crucial reference for researchers and practitioners in the field.
基金supported by the National Natural Science Foundation of China(No.61702347)Hebei Academy of Sciences Basic Research Operating Fund Project(No.2025PF21)。
文摘To address the challenges of multi-scale differences,complex background interference,and unstable small target positioning in visual inspection of power towers,the existing methods still face issues such as insufficient feature interaction and unstable confidence estimation,which lead to performance degradation in complex backgrounds and occlusion conditions.This paper proposes a precise inspection method for key power tower components using autonomous drone positioning.To this end,this paper makes three key improvements to the you only look once version 11(YOLOv11)framework.First,it constructs C3k2-adaptive multi-receptive field block(C3k2-AMRB),combining multiple dilated convolutions with a reparameterization mechanism to significantly expand the receptive field and enhance multi-scale feature extraction.Second,it designs a hierarchical wavelet interaction unit(HWIU),which leverages high-and low-frequency decomposition and reconstruction of wavelet transform(WT)to achieve cross-scale semantic alignment,enhancing feature discriminability in complex backgrounds.Third,it proposes a distribution-aware confidence refinement head(DACR-Head),which adaptively calibrates classification confidence based on the statistical characteristics of the predicted bounding-box corner distribution,improving the localization stability and accuracy of small targets.Experiments on the inspection of power line assets dataset(InsPLAD)dataset show that the integrated approach achieves a component detection accuracy at intersection over union(IoU)=0.5(CDA_(50))of 88.3%and a component detection robustness(CDR_(50:95))of 69.8%,respectively,improvements of 4.4%and 7.0%over the baseline.
文摘[Objective] This study aimed to investigate the adsorption properties of the adsorption tower filled with calcium superphosphate on ammonia volatilized with aer- ation. [Method] Adsorption tower filled with calcium superphosphate was adopted as experimental apparatus, which was constructed by poly vinyl chloride （PVC） circular tubes. With hartshorn as the source of ammonia volatilization, the effect of different ratios of height to diameter of the tower filled with equal amount of calcium super-phosphate on ammonia adsorption was investigated. In addition, adsorption tower with height-diameter ratio of 9.9 was selected to adsorb the ammonia emitted from the composting systems of pig manure and chicken manure with optimized and reg- ulated carbon-nitrogen ratio. [Result] Under certain volatilization rate, calcium super- phosphate particles in the adsorption tower could effectively adsorb the ammonia, and the adsorption efficiency was enhanced with the increase of height-diameter ra-tio, which could reach above 90% with height-diameter ratio of more than 1.1; the ammonia emitted from composting systems of pig manure and chicken manure with optimized and regulated carbon-nitrogen ratio could be completely absorbed using adsorption tower with height-diameter ratio of 9.9 filled with calcium superphosphate accounting for about 8% of the weight of composting materials. [Conclusion] Experi- mental results of this study provided reference for the application of adsorption tower filled with calcium superphosphate in the treatment of waste gas emitted from com- posting materials.
