This paper proposes a channel allocation scheme for multimedia wireless networks,in which a twolayer macro-cell or micro-cell architecture is considered.Macro-cells are used to access high-mobility services;while micr...This paper proposes a channel allocation scheme for multimedia wireless networks,in which a twolayer macro-cell or micro-cell architecture is considered.Macro-cells are used to access high-mobility services;while micro-cells,which are overlaid by the macro-cells,are used to cater low-mobility services.To analyze the scheme,a multidimensional Markov traffic model is firstly developed,in which traffic characteristic of two special periods of time is considered.And then,a pre-emptive channel-borrowing scheme combined with trafficoverflowing strategy for multimedia(voice,video or data) networks is proposed,in which handoff requests can not only borrow channels from adjacent homogenous cells,but also be overflowed to heterogeneous cells.Priority strategies are also dedicated to high-mobility services for they can pre-empt channels being used by low-mobility services in macro-cells.To meet the high quality of service(QoS) requirements of video services and increase the channel utilization ratio,video services can be transformed between real-time services and non-real-time services as necessary.Simulation results show that our schemes can decrease the blocking probabilities and improve the channel utilization.展开更多
In the winter of 2017,southern France was hit by the most severe freeze in a decade,and yet the southern city of Gaiaque,with a population of just 10,000,had 250,000 visitors in town.What attracted them to brave the c...In the winter of 2017,southern France was hit by the most severe freeze in a decade,and yet the southern city of Gaiaque,with a population of just 10,000,had 250,000 visitors in town.What attracted them to brave the cold and rain to visit the small city?A Chinese lantern festival,the first kind of it in France.The lantern festival,jointly展开更多
For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention....For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention. In this study, a water hammer protection scheme combined with an overflow surge tank and a regulating valve was developed. A mathematical model of the overflow surge tank was developed, and an analytical formula for the height of the overflow surge tank was derived. Furthermore, a practical water supply project was used to evaluate the feasibility of the combined protection scheme and analyze the sensitivity of valve regulation rules. The results showed that the combined protection scheme effectively reduced the height of the surge tank, lessened the difficulties related to construction, and reduced the necessary financial investment for the project. The two-stage closing rule articulated as fast first and then slow could minimize the overflow volume of the surge tank when the power failure occurred, while the two-stage opening rule articulated as slow first and then fast could be more conducive to the safety of the water supply system when the pump started up.展开更多
At present,the flow table of the SDN switch is stored in the costly Ternary Content Addressable Memory(TCAM)cache.Due to the cost problem,the number of flow tables that the SDN switch can store is extremely limited,wh...At present,the flow table of the SDN switch is stored in the costly Ternary Content Addressable Memory(TCAM)cache.Due to the cost problem,the number of flow tables that the SDN switch can store is extremely limited,which is far less than the number of traffic,so it is prone to overflow problem,and leads to network paralysis.That has become a bottleneck in restricting the processing capacity of the data center,and will become a weak point focused by attackers.In this paper,we propose an algorithm for the Alarm Switch Remove(ASR)that fully loads the flow table space in SDN,and further put forward an integrated load balancing scheme in SDN.Finally,we use Mininet to verify that the scheme can ease the SDN switch flow table overflow problem and increase network throughput.展开更多
Different abnormalities are commonly encountered in computer network systems.These types of abnormalities can lead to critical data losses or unauthorized access in the systems.Buffer overflow anomaly is a prominent i...Different abnormalities are commonly encountered in computer network systems.These types of abnormalities can lead to critical data losses or unauthorized access in the systems.Buffer overflow anomaly is a prominent issue among these abnormalities,posing a serious threat to network security.The primary objective of this study is to identify the potential risks of buffer overflow that can be caused by functions frequently used in the PHP programming language and to provide solutions to minimize these risks.Static code analyzers are used to detect security vulnerabilities,among which SonarQube stands out with its extensive library,flexible customization options,and reliability in the industry.In this context,a customized rule set aimed at automatically detecting buffer overflows has been developed on the SonarQube platform.The memoization optimization technique used while creating the customized rule set enhances the speed and efficiency of the code analysis process.As a result,the code analysis process is not repeatedly run for code snippets that have been analyzed before,significantly reducing processing time and resource utilization.In this study,a memoization-based rule set was utilized to detect critical security vulnerabilities that could lead to buffer overflow in source codes written in the PHP programming language.Thus,the analysis process is not repeatedly run for code snippets that have been analyzed before,leading to a significant reduction in processing time and resource utilization.In a case study conducted to assess the effectiveness of this method,a significant decrease in the source code analysis time was observed.展开更多
In the context of global climate change,the impact of group-occurring ocean dynamic disasters on China's offshore areas is becoming more and more intense.The study of the effect of existing ocean dynamic disasters...In the context of global climate change,the impact of group-occurring ocean dynamic disasters on China's offshore areas is becoming more and more intense.The study of the effect of existing ocean dynamic disasters on offshore hazard-bearing bodies mostly focuses on the effect of single disaster-causing factors,and it is still insufficient to study storm surge and dynamic wave coupling&reinforcement effects as well as the process of the dynamic response of such hazard-bearing bodies as seawalls.This study firstly realized the synchronous process of water level and wave through continuous tide generation and wave generation by the wave maker and tide generating device,so as to realize the dynamic coupling simulation of storm surge and wave in the laboratory.Then the physical model test of the typical seawall section was carried out under the dynamic coupling of storm surge and wave as well as at a conventional fixed water level respectively.In the process of test wave overtopping discharge and the damage process of the levee crown and backwall of seawalls were observed and compared,and their damage mechanism was also studied.展开更多
Storm surge inundation is a major concern in marine hazard risk assessment during extreme weather conditions.In this study,a high-resolution coupled model(the ADVanced CIRCulation model+the Simulating WAves Nearshore ...Storm surge inundation is a major concern in marine hazard risk assessment during extreme weather conditions.In this study,a high-resolution coupled model(the ADVanced CIRCulation model+the Simulating WAves Nearshore model)was used to investigate the storm surge inundation in the southwestern Hangzhou Bay region during Typhoon Chan-hom in 2015.The simulated hydrodynamic processes(sea surface wave and storm tide)were validated with measured data from wave buoys and tide gauges,indicating that the overall performance of the model was satisfactory.The storm surge inundation in the coastal area was simulated for several idealized control experiments,including different wave effects(wave-enhanced wind stress,wave-enhanced bottom stress,and wave radiation stress).Dike overflowing cases with different dike heights and dike breaking cases with different dike breach lengths were considered in the simulation.The results highlight the necessity of incorporating wave effects in the accurate simulation of storm surge inundation.Dike height significantly influences the magnitude and phase of the maximum inundation area in the dike overflowing cases,and dike breach length is an important factor impacting the magnitude of the maximum inundation area in the dike breaking cases.This study may serve as a useful reference for accurate coastal inundation simulation and risk assessment.展开更多
The simulation of hydrodynamic deep drawing by means of FEM is an efficient method that can relieve experimental burden and find the optimum process parameters. Some problems such as mathematical description of cavity...The simulation of hydrodynamic deep drawing by means of FEM is an efficient method that can relieve experimental burden and find the optimum process parameters. Some problems such as mathematical description of cavity liquid flow pressure must be solved firstly. A math formula about hydrodynamic flow pressure that can be applied in general FEM software was proposed, and good results were gained. It was proved that the theoretical results keep coincident with experimental results.[展开更多
基金the National Natural Science Foundation of China (No.60802058)the Leading Academic Discipline Project of Shanghai Municipal Education Commission (No.J51801)
文摘This paper proposes a channel allocation scheme for multimedia wireless networks,in which a twolayer macro-cell or micro-cell architecture is considered.Macro-cells are used to access high-mobility services;while micro-cells,which are overlaid by the macro-cells,are used to cater low-mobility services.To analyze the scheme,a multidimensional Markov traffic model is firstly developed,in which traffic characteristic of two special periods of time is considered.And then,a pre-emptive channel-borrowing scheme combined with trafficoverflowing strategy for multimedia(voice,video or data) networks is proposed,in which handoff requests can not only borrow channels from adjacent homogenous cells,but also be overflowed to heterogeneous cells.Priority strategies are also dedicated to high-mobility services for they can pre-empt channels being used by low-mobility services in macro-cells.To meet the high quality of service(QoS) requirements of video services and increase the channel utilization ratio,video services can be transformed between real-time services and non-real-time services as necessary.Simulation results show that our schemes can decrease the blocking probabilities and improve the channel utilization.
文摘In the winter of 2017,southern France was hit by the most severe freeze in a decade,and yet the southern city of Gaiaque,with a population of just 10,000,had 250,000 visitors in town.What attracted them to brave the cold and rain to visit the small city?A Chinese lantern festival,the first kind of it in France.The lantern festival,jointly
基金supported by the National Natural Science Foundation of China(Grants No.52179062 and 51879087).
文摘For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention. In this study, a water hammer protection scheme combined with an overflow surge tank and a regulating valve was developed. A mathematical model of the overflow surge tank was developed, and an analytical formula for the height of the overflow surge tank was derived. Furthermore, a practical water supply project was used to evaluate the feasibility of the combined protection scheme and analyze the sensitivity of valve regulation rules. The results showed that the combined protection scheme effectively reduced the height of the surge tank, lessened the difficulties related to construction, and reduced the necessary financial investment for the project. The two-stage closing rule articulated as fast first and then slow could minimize the overflow volume of the surge tank when the power failure occurred, while the two-stage opening rule articulated as slow first and then fast could be more conducive to the safety of the water supply system when the pump started up.
基金supported supported by the National Key Research and Development Program of China(No.2020YFE0200500)CERNET Innovation Project(NGII20190806)。
文摘At present,the flow table of the SDN switch is stored in the costly Ternary Content Addressable Memory(TCAM)cache.Due to the cost problem,the number of flow tables that the SDN switch can store is extremely limited,which is far less than the number of traffic,so it is prone to overflow problem,and leads to network paralysis.That has become a bottleneck in restricting the processing capacity of the data center,and will become a weak point focused by attackers.In this paper,we propose an algorithm for the Alarm Switch Remove(ASR)that fully loads the flow table space in SDN,and further put forward an integrated load balancing scheme in SDN.Finally,we use Mininet to verify that the scheme can ease the SDN switch flow table overflow problem and increase network throughput.
文摘Different abnormalities are commonly encountered in computer network systems.These types of abnormalities can lead to critical data losses or unauthorized access in the systems.Buffer overflow anomaly is a prominent issue among these abnormalities,posing a serious threat to network security.The primary objective of this study is to identify the potential risks of buffer overflow that can be caused by functions frequently used in the PHP programming language and to provide solutions to minimize these risks.Static code analyzers are used to detect security vulnerabilities,among which SonarQube stands out with its extensive library,flexible customization options,and reliability in the industry.In this context,a customized rule set aimed at automatically detecting buffer overflows has been developed on the SonarQube platform.The memoization optimization technique used while creating the customized rule set enhances the speed and efficiency of the code analysis process.As a result,the code analysis process is not repeatedly run for code snippets that have been analyzed before,significantly reducing processing time and resource utilization.In this study,a memoization-based rule set was utilized to detect critical security vulnerabilities that could lead to buffer overflow in source codes written in the PHP programming language.Thus,the analysis process is not repeatedly run for code snippets that have been analyzed before,leading to a significant reduction in processing time and resource utilization.In a case study conducted to assess the effectiveness of this method,a significant decrease in the source code analysis time was observed.
基金Supported by the National Key R&D Program of China(No.2016YFC1402002)the Fifteenth Session Program between China and Bulgaria Scientific and Technological Cooperation Committee(No.15-13)the Major Project of Nanjing Hydraulic Research Institute Funds(Nos.Y218005,Y218006)
文摘In the context of global climate change,the impact of group-occurring ocean dynamic disasters on China's offshore areas is becoming more and more intense.The study of the effect of existing ocean dynamic disasters on offshore hazard-bearing bodies mostly focuses on the effect of single disaster-causing factors,and it is still insufficient to study storm surge and dynamic wave coupling&reinforcement effects as well as the process of the dynamic response of such hazard-bearing bodies as seawalls.This study firstly realized the synchronous process of water level and wave through continuous tide generation and wave generation by the wave maker and tide generating device,so as to realize the dynamic coupling simulation of storm surge and wave in the laboratory.Then the physical model test of the typical seawall section was carried out under the dynamic coupling of storm surge and wave as well as at a conventional fixed water level respectively.In the process of test wave overtopping discharge and the damage process of the levee crown and backwall of seawalls were observed and compared,and their damage mechanism was also studied.
基金supported by the National Key Research and Development Program of China(Nos.2016YFC140 2000,2016YFC1401002,and 2018YFC1407003)the National Natural Science Foundation of China(NSFC)(NosU1706216,41606024,and 41506023)+3 种基金the CAS(Chinese Academy of Sciences)Strategic Priority Project(No.XDA 19060202)the CAS Innovative Foundation(No.CXJJ-16M111)the NSFC Innovative Group(No.41421005)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406402)
文摘Storm surge inundation is a major concern in marine hazard risk assessment during extreme weather conditions.In this study,a high-resolution coupled model(the ADVanced CIRCulation model+the Simulating WAves Nearshore model)was used to investigate the storm surge inundation in the southwestern Hangzhou Bay region during Typhoon Chan-hom in 2015.The simulated hydrodynamic processes(sea surface wave and storm tide)were validated with measured data from wave buoys and tide gauges,indicating that the overall performance of the model was satisfactory.The storm surge inundation in the coastal area was simulated for several idealized control experiments,including different wave effects(wave-enhanced wind stress,wave-enhanced bottom stress,and wave radiation stress).Dike overflowing cases with different dike heights and dike breaking cases with different dike breach lengths were considered in the simulation.The results highlight the necessity of incorporating wave effects in the accurate simulation of storm surge inundation.Dike height significantly influences the magnitude and phase of the maximum inundation area in the dike overflowing cases,and dike breach length is an important factor impacting the magnitude of the maximum inundation area in the dike breaking cases.This study may serve as a useful reference for accurate coastal inundation simulation and risk assessment.
文摘The simulation of hydrodynamic deep drawing by means of FEM is an efficient method that can relieve experimental burden and find the optimum process parameters. Some problems such as mathematical description of cavity liquid flow pressure must be solved firstly. A math formula about hydrodynamic flow pressure that can be applied in general FEM software was proposed, and good results were gained. It was proved that the theoretical results keep coincident with experimental results.[