In the rotor system of aero-engines,the main purpose of a bolted flange connection structure is to transfer torque and speed,and the rotor system may exhibit bolt loosening and connection structure failure under compl...In the rotor system of aero-engines,the main purpose of a bolted flange connection structure is to transfer torque and speed,and the rotor system may exhibit bolt loosening and connection structure failure under complex working conditions,high speed rotation,and external excitation unbalanced force.In addition,the bolted connection structure in the rotor system is mainly subjected to torsional vibration excitation,and using experimental methods to analyze the dynamic response law of different structural parameters of a bolted connection structure under torsional vibration excitation is complicated.Therefore,on the basis of the concentrated mass method and the elastic interaction characteristics within the bolted system,this study establishes dynamic models of one-bolted and multi-bolted connection structural systems under torsional excitation.On the basis of this dynamic model,the dynamic response characteristics of different thread parameters,external excitation,bolt stiffness,and compression stiffness of the connected parts in a one-bolted connection system and the influence laws of different elastic modulus,bolt numbers,and the thickness of the connected parts on the loosening of the multi-bolted connection system are analyzed.Results show that small thread pitch,external excitation amplitude and frequency,compressive stiffness,bolt stiffness,and elastic modulus and large tooth angle,number of bolts,and thickness of connected parts can appropriately improve the anti-loosening performance of the bolted connection system.This study also uses a comparative verification method combining finite element simulation and experiment to verify the correctness of the established dynamic model effectively.展开更多
This paper proposes a reliability evaluation model for a multi-dimensional network system,which has potential to be applied to the internet of things or other practical networks.A multi-dimensional network system with...This paper proposes a reliability evaluation model for a multi-dimensional network system,which has potential to be applied to the internet of things or other practical networks.A multi-dimensional network system with one source element and multiple sink elements is considered first.Each element can con-nect with other elements within a stochastic connection ranges.The system is regarded as successful as long as the source ele-ment remains connected with all sink elements.An importance measure is proposed to evaluate the performance of non-source elements.Furthermore,to calculate the system reliability and the element importance measure,a multi-valued decision diagram based approach is structured and its complexity is analyzed.Finally,a numerical example about the signal transfer station system is illustrated to analyze the system reliability and the ele-ment importance measure.展开更多
Climate change is having an increasing impact on coastal infrastructure,leading to more frequent and intensified wave activity,including higher waves driven by typhoons and abnormal sea conditions.Consequently,issues ...Climate change is having an increasing impact on coastal infrastructure,leading to more frequent and intensified wave activity,including higher waves driven by typhoons and abnormal sea conditions.Consequently,issues related to the stability of existing port structures,such as caissons,have become a significant concern.In particular,gravity-type caisson on the land side of coastal port structures require enhanced stability and safety.Gravity-type caissons,which resist external forces through their own weight,are highly vulnerable to functional failures,such as sliding displacement,triggered by abnormal waves shifting specific caissons.The destruction of caisson and quay walls can lead to substantial recovery costs,necessitating improvements in caisson stability to address the challenges posed by increased wave forces and changes in port logistics due to larger vessels.One approach to enhancing caisson stability is the use of long caissons.Long caisson is commonly used where a breakwater is needed to withstand wave action and distribute forces evenly along a length of breakwater.The construction of caissons faces challenges due to limitations on the size of individual units imposed by construction conditions,launching methods,and marine crane requirements.Therefore,connecting multiple caissons to form long caissons presents a viable alternative.This study suggested two connection methods for long caissons.The first method was a hemisphere caisson,which allows the connection parts to seat against each other under self-weight during construction.The second method was a displacement-allowing connection utilizing rubble(embedded rebar connection within riprap connection).This approach allows some displacement while employing rebar to resist excessive deformation,thereby dispersing the resulting wave forces to adjacent caissons.Performance comparisons between the developed connections and conventional gravity-type caissons were conducted using a finite element analysis model.The results indicate that the proposed connections demonstrate improved resistance to wave forces compared to traditional caissons without such connections.Further studies should include field applications and performance evaluations of various caisson sizes under different environmental and geological conditions.展开更多
The Arctic plays a pivotal role in the Earth’s climate system,with its rapid transformation exerting profound impacts on global climate dynamics,ecosystems,and human societies.In recent decades,Arctic warming has sig...The Arctic plays a pivotal role in the Earth’s climate system,with its rapid transformation exerting profound impacts on global climate dynamics,ecosystems,and human societies.In recent decades,Arctic warming has significantly outpaced the global mean temperature increase,driving the enhanced sea ice decline,the accelerated mass loss of the Greenland Ice Sheet,permafrost degradation,and glacier retreat.These changes modulate atmospheric and oceanic circulation patterns,establishing teleconnections with mid-and low-latitude climate systems.Investigating the historical evolution,current state,and projected future trends of the Arctic climate system,as well as its global impacts,is crucial for elucidating the mechanisms underlying Arctic amplification,refining climate change projections,attributing extreme weather and climate events,and informing sustainable development strategies.展开更多
On November 3,the Philippine Embassy in China and the Philippine Department of Tourism jointly launched the Philippine e-visa system in Beijing,aiming to make travel more convenient for Chinese visitors and promote pe...On November 3,the Philippine Embassy in China and the Philippine Department of Tourism jointly launched the Philippine e-visa system in Beijing,aiming to make travel more convenient for Chinese visitors and promote people-to-people exchange between the two countries.Philippine Ambassador to China Jaime FlorCruz said the government launched the program to ensure a smoother visa experience for Chinese applicants.展开更多
Founded in September 2020,the International SparkLink Alliance(iSLA)now has approximately 1,200 members in diverse sectors including terminals,homes,vehicles,manufacturing,transportation,finance and healthcare.The iSL...Founded in September 2020,the International SparkLink Alliance(iSLA)now has approximately 1,200 members in diverse sectors including terminals,homes,vehicles,manufacturing,transportation,finance and healthcare.The iSLA has established a technical standards system for wireless short-range communication covering full-stack standards such as the end-to-end protocol system.展开更多
Floodplain wetlands are invaluable ecosystems providing numerous ecological benefits,yet they face a global crisis necessitating sustainable preservation efforts.This study examines the depletion of floodplain wetland...Floodplain wetlands are invaluable ecosystems providing numerous ecological benefits,yet they face a global crisis necessitating sustainable preservation efforts.This study examines the depletion of floodplain wetlands within the Hastinapur Wildlife Sanctuary(HWLS)in Uttar Pradesh.Encroachment activities such as grazing,agriculture,and human settlements have fragmented and degraded critical wetland ecosystems.Additionally,irrigation projects,dam construction,and water diversion have disrupted natural water flow and availability.To assess wetland inundation in 2023,five classification techniques were employed:Random Forest(RF),Support Vector Machine(SVM),artificial neural network(ANN),Spectral Information Divergence(SID),and Maximum Likelihood Classifier(MLC).SVM emerged as the most precise method,as determined by kappa coefficient and index-based validation.Consequently,the SVM classifier was used to model wetland inundation areas from 1983 to 2023 and analyze spatiotemporal changes and fragmentation patterns.The findings revealed that the SVM clas-sifier accurately mapped 2023 wetland areas.The modeled time-series data demonstrated a 62.55%and 38.12%reduction in inundated wetland areas over the past 40 years in the pre-and post-monsoon periods,respectively.Fragmentation analysis indicated an 86.27%decrease in large core wetland areas in the pre-monsoon period,signifying severe habitat degradation.This rapid decline in wetlands within protected areas raises concerns about their ecological impacts.By linking wetland loss to global sustainability objectives,this study underscores the global urgency for strengthened wetland protection measures and highlights the need for integrating wetland conservation into broader sustainable development goals.Effective policies and adaptive management strategies are crucial for preserving these ecosystems and their vital services,which are essential for biodiversity,climate regulation,and human well-being.展开更多
Traffic at urban intersections frequently encounters unexpected obstructions,resulting in congestion due to uncooperative and priority-based driving behavior.This paper presents an optimal right-turn coordination syst...Traffic at urban intersections frequently encounters unexpected obstructions,resulting in congestion due to uncooperative and priority-based driving behavior.This paper presents an optimal right-turn coordination system for Connected and Automated Vehicles(CAVs)at single-lane intersections,particularly in the context of left-hand side driving on roads.The goal is to facilitate smooth right turns for certain vehicles without creating bottlenecks.We consider that all approaching vehicles share relevant information through vehicular communications.The Intersection Coordination Unit(ICU)processes this information and communicates the optimal crossing or turning times to the vehicles.The primary objective of this coordination is to minimize overall traffic delays,which also helps improve the fuel consumption of vehicles.By considering information from upcoming vehicles at the intersection,the coordination system solves an optimization problem to determine the best timing for executing right turns,ultimately minimizing the total delay for all vehicles.The proposed coordination system is evaluated at a typical urban intersection,and its performance is compared to traditional traffic systems.Numerical simulation results indicate that the proposed coordination system significantly enhances the average traffic speed and fuel consumption compared to the traditional traffic system in various scenarios.展开更多
The advent of sixth-generation(6G)networks introduces unprecedented challenges in achieving seamless connectivity,ultra-low latency,and efficient resource management in highly dynamic environments.Although fifth-gener...The advent of sixth-generation(6G)networks introduces unprecedented challenges in achieving seamless connectivity,ultra-low latency,and efficient resource management in highly dynamic environments.Although fifth-generation(5G)networks transformed mobile broadband and machine-type communications at massive scales,their properties of scaling,interference management,and latency remain a limitation in dense high mobility settings.To overcome these limitations,artificial intelligence(AI)and unmanned aerial vehicles(UAVs)have emerged as potential solutions to develop versatile,dynamic,and energy-efficient communication systems.The study proposes an AI-based UAV architecture that utilizes cooperative reinforcement learning(CoRL)to manage an autonomous network.The UAVs collaborate by sharing local observations and real-time state exchanges to optimize user connectivity,movement directions,allocate power,and resource distribution.Unlike conventional centralized or autonomous methods,CoRL involves joint state sharing and conflict-sensitive reward shaping,which ensures fair coverage,less interference,and enhanced adaptability in a dynamic urban environment.Simulations conducted in smart city scenarios with 10 UAVs and 50 ground users demonstrate that the proposed CoRL-based UAV system increases user coverage by up to 10%,achieves convergence 40%faster,and reduces latency and energy consumption by 30%compared with centralized and decentralized baselines.Furthermore,the distributed nature of the algorithm ensures scalability and flexibility,making it well-suited for future large-scale 6G deployments.The results highlighted that AI-enabled UAV systems enhance connectivity,support ultra-reliable low-latency communications(URLLC),and improve 6G network efficiency.Future work will extend the framework with adaptive modulation,beamforming-aware positioning,and real-world testbed deployment.展开更多
The effects of random long-range connections （shortcuts） on the transitions of neural firing patterns in coupled Hindmarsh-Rose neurons are investigated, where each neuron is subjected to an external current. It is ...The effects of random long-range connections （shortcuts） on the transitions of neural firing patterns in coupled Hindmarsh-Rose neurons are investigated, where each neuron is subjected to an external current. It is found that, on one hand, the system can achieve the transition of neural firing patterns from the fewer-period state to the multi-period one, when the number of the added shortcuts in the neural network is greater than a threshold value, indicating the occurrence of in-transition of neural firing patterns. On the other hand, for a stronger coupling strength, we can also find the similar but reverse results by adding some proper random connections. In addition, the influences of system size and coupling strength on such transition behavior, as well as the internality between the transition degree of firing patterns and its critical characteristics for different external stimulation current, are also discussed.展开更多
Efficient and accurate strength analysis of bolted connections is essential in analyzing the integral thermal protection system（ITPS） of hypersonic vehicles, since the system bears severe loads and structural failur...Efficient and accurate strength analysis of bolted connections is essential in analyzing the integral thermal protection system（ITPS） of hypersonic vehicles, since the system bears severe loads and structural failures usually occur at the connections. Investigations of composite mechanical properties used in ITPS are still in progress as the architecture of the composites is complex. A new method is proposed in this paper for strength analysis of bolted connections by investigating the elastic behavior and failure strength of three-dimensional C/C orthogonal composites used in ITPS. In this method a multi-scale finite element method incorporating the global–local method is established to ensure high efficiency in macro-scale and precision in meso-scale in analysis.Simulation results reveal that predictions of material properties show reasonable accuracy compared with test results. And the multi-scale method can analyze the strength of connections efficiently and accurately.展开更多
As a new type of marine structure,floating breakwater can provide suitable water area for coastal residents.In this paper,a multi-module floating breakwater with three cylinders was designed.According to the character...As a new type of marine structure,floating breakwater can provide suitable water area for coastal residents.In this paper,a multi-module floating breakwater with three cylinders was designed.According to the characteristics of each module,the elastic connector was created.The cabins with functions such as living,generating electricity and entertainment were arranged.A linear spring constrained design wave(LSCDW)method for strength analysis of floating marine structures with multi-module elastic connections was proposed.The numerical model was verified by 1:50 similarity ratio in the test tank.According to the analysis of design wave and extreme wave conditions,considering the mooring loads and environmental loads and connector loads,the overall strength of breakwater was analyzed by LSCDW method.These studies can provide new insights and theoretical guidance for the design of multi-module floating structures.展开更多
The increasing demand for industrial automation and intelligence has put forward higher requirements for the reliability of industrial wireless communication technology.As an international standard based on 802.11,Wir...The increasing demand for industrial automation and intelligence has put forward higher requirements for the reliability of industrial wireless communication technology.As an international standard based on 802.11,Wireless networks for Industrial Automation-Factory Automation(WIA-FA)greatly improves the reliability in factory automation scenarios by Time Division Multiple Access(TDMA).However,in ultra-dense WIA-FA networks with mobile users,the basic connection management mechanism is inefficient.Most of the handover and resource management algorithms are all based on frequency division multiplexing,not suitable for the TDMA in the WIA-FA network.Therefore,we propose Load-aware Connection Management(LACM)algorithm to adjust the linkage and balance the load of access devices to avoid blocking and improve the reliability of the system.And then we simulate the algorithm to find the optimal settings of the parameters.After comparing with other existing algorithms,the result of the simulation proves that LACM is more efficient in reliability and maintains high reliability of more than 99.8%even in the ultra-dense moving scenario with 1500 field devices.Besides,this algorithm ensures that only a few signaling exchanges are required to ensure load bal-ancing,which is no more than 5 times,and less than half of the best state-of-the-art algorithm.展开更多
In this paper, based on new Lyapunov function, the asymptotic properties of the dynamic neural system with asymmetric connection weights are investigated. Since the dynamic neural system with asymmetric connection wei...In this paper, based on new Lyapunov function, the asymptotic properties of the dynamic neural system with asymmetric connection weights are investigated. Since the dynamic neural system with asymmetric connection weights is more general than that with symmetric ones, the new results are significant in both theory and applications. Specially the new result can cover the asymptotic stability results of linear systems as special cases.展开更多
The geodesic characteristic of equations of motion for nonautonomous constrained mechanical systems is studied in the modern setting of global differential geometry. A necessary and sufficient condition for the dynami...The geodesic characteristic of equations of motion for nonautonomous constrained mechanical systems is studied in the modern setting of global differential geometry. A necessary and sufficient condition for the dynamical flow of a nonautonomous mechanical system with geodesic characteristic was obtained with respect to a connection of 1-jet bundle. The dynamical flow concerning the non-autonomous case motion of an nonautonomous mechanical system with constraints can be always represented by the motion along the geodesic line of torsion-free connection on 1-jet bundle, which is different from the case in an autonomous mechanical system.展开更多
Synchronization of N different coupled chaotic systems with ring and chain connections is investigated. The New system, the Chen system, the Lii system, the Lorenz system, and the Rossler system are used as examples i...Synchronization of N different coupled chaotic systems with ring and chain connections is investigated. The New system, the Chen system, the Lii system, the Lorenz system, and the Rossler system are used as examples in verifying effectiveness of the method. Based on the Lyapunov stability theory, the form of the controller is designed and the area of the coupling coefficients is determined. Simulations indicate that global synchronization of the N different chaotic systems can be realized by choosing appropriate coupling coefficients by using the controller.展开更多
Taking the connection zone between Shenyang and Fushun as an example,urbanization indicator system was established from the aspects of population,economy,space and society,and the comprehensive evaluation indicator sy...Taking the connection zone between Shenyang and Fushun as an example,urbanization indicator system was established from the aspects of population,economy,space and society,and the comprehensive evaluation indicator system of water ecological environment was also established from the aspects of water ecological environmental pressure,state and response. Based on the evaluation of comprehensive level of urbanization and the comprehensive quality of water ecological environment,their changing trends during 2000-2014 were analyzed,and the response model between them was established. The composite index of urbanization in the connection zone between Shenyang and Fushun always increased from 2000 to 2014,and urbanization developed rapidly after 2004. The comprehensive quality of water ecological environment decreased firstly and then increased during 2000-2014. The response relationship between urbanization comprehensive index and water ecological comprehensive index during 2000-2014 could be expressed by a cubic curve.展开更多
Primary and secondary networks are treated as a whole in indirect heating systems, and an advanced new temperature-flow regulation method is presented whose flow ratio is greater than 60% in a secondary network and 30...Primary and secondary networks are treated as a whole in indirect heating systems, and an advanced new temperature-flow regulation method is presented whose flow ratio is greater than 60% in a secondary network and 30% in a primary network when under a partial load. Through deducing and optimizing an exponential function flow regulation rule, the formulae of flow regulation and the supply and return water temperatures are obtained, and their relevant curves are plotted. After comparison, it is found that this control method has a huge energy conservation space, and it should therefore be generalized soon.展开更多
Stability of Volterra systems are discusses by subpositive definite matrix, and some new criterions for Volterra systems on overall situation stability, sector stability and connection stability are acquired. These re...Stability of Volterra systems are discusses by subpositive definite matrix, and some new criterions for Volterra systems on overall situation stability, sector stability and connection stability are acquired. These results expand or improve some existing criterions.展开更多
In practical engineering, many phenomena are described as a discontinuous function of a state variable, and the discontinuity is usually the main reason for the degradation of the control performance. For example, in ...In practical engineering, many phenomena are described as a discontinuous function of a state variable, and the discontinuity is usually the main reason for the degradation of the control performance. For example, in the set-point control problem of mechanical systems, the static friction （described by a sgn function of velocity of the contacting faces） causes undesired positioning error. In this paper, we will investigate the stabilization problem for a class of nonlinear systems that consist of two subsystems with cascaded connection. We will show the basic idea with a special case first, and then the result will be extended to more general cases. Some interesting numerical examples will be given to demonstrate the effectiveness of the proposed design approach.展开更多
基金the financial support of the National Natural Science Foundation of China(NSFC)(Grant No.52375113)the Natural Science Foundation of Liaoning Province of China(Grant No.2022-MS-298)+1 种基金Shenyang Youth Science and Technology Innovation Talent Fund,China(Grant No.RC230309)the Scientific Research Fund of Liaoning Education Department,China(Grant No.LJKMZ20220531).
文摘In the rotor system of aero-engines,the main purpose of a bolted flange connection structure is to transfer torque and speed,and the rotor system may exhibit bolt loosening and connection structure failure under complex working conditions,high speed rotation,and external excitation unbalanced force.In addition,the bolted connection structure in the rotor system is mainly subjected to torsional vibration excitation,and using experimental methods to analyze the dynamic response law of different structural parameters of a bolted connection structure under torsional vibration excitation is complicated.Therefore,on the basis of the concentrated mass method and the elastic interaction characteristics within the bolted system,this study establishes dynamic models of one-bolted and multi-bolted connection structural systems under torsional excitation.On the basis of this dynamic model,the dynamic response characteristics of different thread parameters,external excitation,bolt stiffness,and compression stiffness of the connected parts in a one-bolted connection system and the influence laws of different elastic modulus,bolt numbers,and the thickness of the connected parts on the loosening of the multi-bolted connection system are analyzed.Results show that small thread pitch,external excitation amplitude and frequency,compressive stiffness,bolt stiffness,and elastic modulus and large tooth angle,number of bolts,and thickness of connected parts can appropriately improve the anti-loosening performance of the bolted connection system.This study also uses a comparative verification method combining finite element simulation and experiment to verify the correctness of the established dynamic model effectively.
基金supported by the National Natural Science Foundation of China(72101025,72271049),the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities,FRF-IDRY-24-024)the Hebei Natural Science Foundation(F2023501011)+1 种基金the Fundamental Research Funds for the Central Universities(FRF-TP-20-073A1)the R&D Program of Beijing Municipal Education Commission(KM202411232015).
文摘This paper proposes a reliability evaluation model for a multi-dimensional network system,which has potential to be applied to the internet of things or other practical networks.A multi-dimensional network system with one source element and multiple sink elements is considered first.Each element can con-nect with other elements within a stochastic connection ranges.The system is regarded as successful as long as the source ele-ment remains connected with all sink elements.An importance measure is proposed to evaluate the performance of non-source elements.Furthermore,to calculate the system reliability and the element importance measure,a multi-valued decision diagram based approach is structured and its complexity is analyzed.Finally,a numerical example about the signal transfer station system is illustrated to analyze the system reliability and the ele-ment importance measure.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(Nos.RS-2023-00212586 and RS-2024-00348557)the Korea Maritime&Ocean University Research Fund in 2024.
文摘Climate change is having an increasing impact on coastal infrastructure,leading to more frequent and intensified wave activity,including higher waves driven by typhoons and abnormal sea conditions.Consequently,issues related to the stability of existing port structures,such as caissons,have become a significant concern.In particular,gravity-type caisson on the land side of coastal port structures require enhanced stability and safety.Gravity-type caissons,which resist external forces through their own weight,are highly vulnerable to functional failures,such as sliding displacement,triggered by abnormal waves shifting specific caissons.The destruction of caisson and quay walls can lead to substantial recovery costs,necessitating improvements in caisson stability to address the challenges posed by increased wave forces and changes in port logistics due to larger vessels.One approach to enhancing caisson stability is the use of long caissons.Long caisson is commonly used where a breakwater is needed to withstand wave action and distribute forces evenly along a length of breakwater.The construction of caissons faces challenges due to limitations on the size of individual units imposed by construction conditions,launching methods,and marine crane requirements.Therefore,connecting multiple caissons to form long caissons presents a viable alternative.This study suggested two connection methods for long caissons.The first method was a hemisphere caisson,which allows the connection parts to seat against each other under self-weight during construction.The second method was a displacement-allowing connection utilizing rubble(embedded rebar connection within riprap connection).This approach allows some displacement while employing rebar to resist excessive deformation,thereby dispersing the resulting wave forces to adjacent caissons.Performance comparisons between the developed connections and conventional gravity-type caissons were conducted using a finite element analysis model.The results indicate that the proposed connections demonstrate improved resistance to wave forces compared to traditional caissons without such connections.Further studies should include field applications and performance evaluations of various caisson sizes under different environmental and geological conditions.
文摘The Arctic plays a pivotal role in the Earth’s climate system,with its rapid transformation exerting profound impacts on global climate dynamics,ecosystems,and human societies.In recent decades,Arctic warming has significantly outpaced the global mean temperature increase,driving the enhanced sea ice decline,the accelerated mass loss of the Greenland Ice Sheet,permafrost degradation,and glacier retreat.These changes modulate atmospheric and oceanic circulation patterns,establishing teleconnections with mid-and low-latitude climate systems.Investigating the historical evolution,current state,and projected future trends of the Arctic climate system,as well as its global impacts,is crucial for elucidating the mechanisms underlying Arctic amplification,refining climate change projections,attributing extreme weather and climate events,and informing sustainable development strategies.
文摘On November 3,the Philippine Embassy in China and the Philippine Department of Tourism jointly launched the Philippine e-visa system in Beijing,aiming to make travel more convenient for Chinese visitors and promote people-to-people exchange between the two countries.Philippine Ambassador to China Jaime FlorCruz said the government launched the program to ensure a smoother visa experience for Chinese applicants.
文摘Founded in September 2020,the International SparkLink Alliance(iSLA)now has approximately 1,200 members in diverse sectors including terminals,homes,vehicles,manufacturing,transportation,finance and healthcare.The iSLA has established a technical standards system for wireless short-range communication covering full-stack standards such as the end-to-end protocol system.
基金support through the“Trans-Disciplinary Research”Grant(No.R/Dev/IoE/TDRProjects/2023-24/61658),which played a crucial role in enabling this research endeavor.
文摘Floodplain wetlands are invaluable ecosystems providing numerous ecological benefits,yet they face a global crisis necessitating sustainable preservation efforts.This study examines the depletion of floodplain wetlands within the Hastinapur Wildlife Sanctuary(HWLS)in Uttar Pradesh.Encroachment activities such as grazing,agriculture,and human settlements have fragmented and degraded critical wetland ecosystems.Additionally,irrigation projects,dam construction,and water diversion have disrupted natural water flow and availability.To assess wetland inundation in 2023,five classification techniques were employed:Random Forest(RF),Support Vector Machine(SVM),artificial neural network(ANN),Spectral Information Divergence(SID),and Maximum Likelihood Classifier(MLC).SVM emerged as the most precise method,as determined by kappa coefficient and index-based validation.Consequently,the SVM classifier was used to model wetland inundation areas from 1983 to 2023 and analyze spatiotemporal changes and fragmentation patterns.The findings revealed that the SVM clas-sifier accurately mapped 2023 wetland areas.The modeled time-series data demonstrated a 62.55%and 38.12%reduction in inundated wetland areas over the past 40 years in the pre-and post-monsoon periods,respectively.Fragmentation analysis indicated an 86.27%decrease in large core wetland areas in the pre-monsoon period,signifying severe habitat degradation.This rapid decline in wetlands within protected areas raises concerns about their ecological impacts.By linking wetland loss to global sustainability objectives,this study underscores the global urgency for strengthened wetland protection measures and highlights the need for integrating wetland conservation into broader sustainable development goals.Effective policies and adaptive management strategies are crucial for preserving these ecosystems and their vital services,which are essential for biodiversity,climate regulation,and human well-being.
基金supported by the Japan Society for the Promotion of Science(JSPS)Grants-in-Aid for Scientific Research(C)23K03898.
文摘Traffic at urban intersections frequently encounters unexpected obstructions,resulting in congestion due to uncooperative and priority-based driving behavior.This paper presents an optimal right-turn coordination system for Connected and Automated Vehicles(CAVs)at single-lane intersections,particularly in the context of left-hand side driving on roads.The goal is to facilitate smooth right turns for certain vehicles without creating bottlenecks.We consider that all approaching vehicles share relevant information through vehicular communications.The Intersection Coordination Unit(ICU)processes this information and communicates the optimal crossing or turning times to the vehicles.The primary objective of this coordination is to minimize overall traffic delays,which also helps improve the fuel consumption of vehicles.By considering information from upcoming vehicles at the intersection,the coordination system solves an optimization problem to determine the best timing for executing right turns,ultimately minimizing the total delay for all vehicles.The proposed coordination system is evaluated at a typical urban intersection,and its performance is compared to traditional traffic systems.Numerical simulation results indicate that the proposed coordination system significantly enhances the average traffic speed and fuel consumption compared to the traditional traffic system in various scenarios.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(RS-2025-00559546)supported by the IITP(Institute of Information&Coummunications Technology Planning&Evaluation)-ITRC(Information Technology Research Center)grant funded by the Korea government(Ministry of Science and ICT)(IITP-2025-RS-2023-00259004).
文摘The advent of sixth-generation(6G)networks introduces unprecedented challenges in achieving seamless connectivity,ultra-low latency,and efficient resource management in highly dynamic environments.Although fifth-generation(5G)networks transformed mobile broadband and machine-type communications at massive scales,their properties of scaling,interference management,and latency remain a limitation in dense high mobility settings.To overcome these limitations,artificial intelligence(AI)and unmanned aerial vehicles(UAVs)have emerged as potential solutions to develop versatile,dynamic,and energy-efficient communication systems.The study proposes an AI-based UAV architecture that utilizes cooperative reinforcement learning(CoRL)to manage an autonomous network.The UAVs collaborate by sharing local observations and real-time state exchanges to optimize user connectivity,movement directions,allocate power,and resource distribution.Unlike conventional centralized or autonomous methods,CoRL involves joint state sharing and conflict-sensitive reward shaping,which ensures fair coverage,less interference,and enhanced adaptability in a dynamic urban environment.Simulations conducted in smart city scenarios with 10 UAVs and 50 ground users demonstrate that the proposed CoRL-based UAV system increases user coverage by up to 10%,achieves convergence 40%faster,and reduces latency and energy consumption by 30%compared with centralized and decentralized baselines.Furthermore,the distributed nature of the algorithm ensures scalability and flexibility,making it well-suited for future large-scale 6G deployments.The results highlighted that AI-enabled UAV systems enhance connectivity,support ultra-reliable low-latency communications(URLLC),and improve 6G network efficiency.Future work will extend the framework with adaptive modulation,beamforming-aware positioning,and real-world testbed deployment.
文摘The effects of random long-range connections （shortcuts） on the transitions of neural firing patterns in coupled Hindmarsh-Rose neurons are investigated, where each neuron is subjected to an external current. It is found that, on one hand, the system can achieve the transition of neural firing patterns from the fewer-period state to the multi-period one, when the number of the added shortcuts in the neural network is greater than a threshold value, indicating the occurrence of in-transition of neural firing patterns. On the other hand, for a stronger coupling strength, we can also find the similar but reverse results by adding some proper random connections. In addition, the influences of system size and coupling strength on such transition behavior, as well as the internality between the transition degree of firing patterns and its critical characteristics for different external stimulation current, are also discussed.
基金co-supported by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe National Natural Science Foundation of China (No. 11302105)
文摘Efficient and accurate strength analysis of bolted connections is essential in analyzing the integral thermal protection system（ITPS） of hypersonic vehicles, since the system bears severe loads and structural failures usually occur at the connections. Investigations of composite mechanical properties used in ITPS are still in progress as the architecture of the composites is complex. A new method is proposed in this paper for strength analysis of bolted connections by investigating the elastic behavior and failure strength of three-dimensional C/C orthogonal composites used in ITPS. In this method a multi-scale finite element method incorporating the global–local method is established to ensure high efficiency in macro-scale and precision in meso-scale in analysis.Simulation results reveal that predictions of material properties show reasonable accuracy compared with test results. And the multi-scale method can analyze the strength of connections efficiently and accurately.
基金the National Natural Science Foundation of China(No.52071161)。
文摘As a new type of marine structure,floating breakwater can provide suitable water area for coastal residents.In this paper,a multi-module floating breakwater with three cylinders was designed.According to the characteristics of each module,the elastic connector was created.The cabins with functions such as living,generating electricity and entertainment were arranged.A linear spring constrained design wave(LSCDW)method for strength analysis of floating marine structures with multi-module elastic connections was proposed.The numerical model was verified by 1:50 similarity ratio in the test tank.According to the analysis of design wave and extreme wave conditions,considering the mooring loads and environmental loads and connector loads,the overall strength of breakwater was analyzed by LSCDW method.These studies can provide new insights and theoretical guidance for the design of multi-module floating structures.
基金supported by NSFC project(grant No.61971359)Chongqing Municipal Key Laboratory of Institutions of Higher Education(grant No.cquptmct-202104)+1 种基金Fundamental Research Funds for the Central Universities,Sichuan Science and Technology Project(grant no.2021YFQ0053)State Key Laboratory of Rail Transit Engineering Informatization(FSDI).
文摘The increasing demand for industrial automation and intelligence has put forward higher requirements for the reliability of industrial wireless communication technology.As an international standard based on 802.11,Wireless networks for Industrial Automation-Factory Automation(WIA-FA)greatly improves the reliability in factory automation scenarios by Time Division Multiple Access(TDMA).However,in ultra-dense WIA-FA networks with mobile users,the basic connection management mechanism is inefficient.Most of the handover and resource management algorithms are all based on frequency division multiplexing,not suitable for the TDMA in the WIA-FA network.Therefore,we propose Load-aware Connection Management(LACM)algorithm to adjust the linkage and balance the load of access devices to avoid blocking and improve the reliability of the system.And then we simulate the algorithm to find the optimal settings of the parameters.After comparing with other existing algorithms,the result of the simulation proves that LACM is more efficient in reliability and maintains high reliability of more than 99.8%even in the ultra-dense moving scenario with 1500 field devices.Besides,this algorithm ensures that only a few signaling exchanges are required to ensure load bal-ancing,which is no more than 5 times,and less than half of the best state-of-the-art algorithm.
文摘In this paper, based on new Lyapunov function, the asymptotic properties of the dynamic neural system with asymmetric connection weights are investigated. Since the dynamic neural system with asymmetric connection weights is more general than that with symmetric ones, the new results are significant in both theory and applications. Specially the new result can cover the asymptotic stability results of linear systems as special cases.
文摘The geodesic characteristic of equations of motion for nonautonomous constrained mechanical systems is studied in the modern setting of global differential geometry. A necessary and sufficient condition for the dynamical flow of a nonautonomous mechanical system with geodesic characteristic was obtained with respect to a connection of 1-jet bundle. The dynamical flow concerning the non-autonomous case motion of an nonautonomous mechanical system with constraints can be always represented by the motion along the geodesic line of torsion-free connection on 1-jet bundle, which is different from the case in an autonomous mechanical system.
基金the Natural Science Foundation of Liaoning Province(No.20052151)the Innovative Team Program of Liaoning Educational Committee
文摘Synchronization of N different coupled chaotic systems with ring and chain connections is investigated. The New system, the Chen system, the Lii system, the Lorenz system, and the Rossler system are used as examples in verifying effectiveness of the method. Based on the Lyapunov stability theory, the form of the controller is designed and the area of the coupling coefficients is determined. Simulations indicate that global synchronization of the N different chaotic systems can be realized by choosing appropriate coupling coefficients by using the controller.
基金Supported by the National Special Science and Technology Project for Water Pollution Control and Management(2014ZX07202011)
文摘Taking the connection zone between Shenyang and Fushun as an example,urbanization indicator system was established from the aspects of population,economy,space and society,and the comprehensive evaluation indicator system of water ecological environment was also established from the aspects of water ecological environmental pressure,state and response. Based on the evaluation of comprehensive level of urbanization and the comprehensive quality of water ecological environment,their changing trends during 2000-2014 were analyzed,and the response model between them was established. The composite index of urbanization in the connection zone between Shenyang and Fushun always increased from 2000 to 2014,and urbanization developed rapidly after 2004. The comprehensive quality of water ecological environment decreased firstly and then increased during 2000-2014. The response relationship between urbanization comprehensive index and water ecological comprehensive index during 2000-2014 could be expressed by a cubic curve.
文摘Primary and secondary networks are treated as a whole in indirect heating systems, and an advanced new temperature-flow regulation method is presented whose flow ratio is greater than 60% in a secondary network and 30% in a primary network when under a partial load. Through deducing and optimizing an exponential function flow regulation rule, the formulae of flow regulation and the supply and return water temperatures are obtained, and their relevant curves are plotted. After comparison, it is found that this control method has a huge energy conservation space, and it should therefore be generalized soon.
基金Supported by the Natural Sciences Research Foundation of Department of Education of Jiangsu Province(03KJD110088,05KJD110058)
文摘Stability of Volterra systems are discusses by subpositive definite matrix, and some new criterions for Volterra systems on overall situation stability, sector stability and connection stability are acquired. These results expand or improve some existing criterions.
文摘In practical engineering, many phenomena are described as a discontinuous function of a state variable, and the discontinuity is usually the main reason for the degradation of the control performance. For example, in the set-point control problem of mechanical systems, the static friction （described by a sgn function of velocity of the contacting faces） causes undesired positioning error. In this paper, we will investigate the stabilization problem for a class of nonlinear systems that consist of two subsystems with cascaded connection. We will show the basic idea with a special case first, and then the result will be extended to more general cases. Some interesting numerical examples will be given to demonstrate the effectiveness of the proposed design approach.
