According to low earth orbit（LEO） satellite systems with users of different levels, a dynamic channel reservation scheme based on priorities is proposed. Dynamic calculation of the thresholds for reserved channels i...According to low earth orbit（LEO） satellite systems with users of different levels, a dynamic channel reservation scheme based on priorities is proposed. Dynamic calculation of the thresholds for reserved channels is the key of this strategy. In order to obtain the optimal thresholds, the traffic is predicted based on the high-speed deterministic movement property of LEO satellites firstly. Then, a channel allocation model based on Markov is established. Finally, the solution of the model is obtained based on the genetic algorithm. Without user location, this strategy effectively reduces handover failures and improves channel utilization by adjusting dynamically the thresholds according to traffic conditions. The simulation results show that the system＇s overall quality of service can be improved by this strategy.展开更多
The specific features of the CAN bus is analyzed and the functional performances in the Controller Area Network (CAN) bus system of Wire Harness Assembly Machine (WHAM) is discussed. A reasonable definition of applica...The specific features of the CAN bus is analyzed and the functional performances in the Controller Area Network (CAN) bus system of Wire Harness Assembly Machine (WHAM) is discussed. A reasonable definition of application layer which is not defined in the CAN specification is given for the control system of WHAM. So application layer planning of CAN bus for dynamic priority is presented. With the mechanism of dynamic priority,it becomes easily to find out the error nodes in the CAN bus system of WHAM and realize multi-mode operation.展开更多
One problem with the existing dynamic exclusive bus lane strategies is that bus signal priority strategies with multi-phase priority request at intersections are not adequately considered.The principle of bus signal p...One problem with the existing dynamic exclusive bus lane strategies is that bus signal priority strategies with multi-phase priority request at intersections are not adequately considered.The principle of bus signal priority level was designed based on the isolated multi-phase structure principle consideration of the bus signal priority,and a new priority approach for the dynamic exclusive bus lane was proposed.Two types of priority strategies,green extension and red truncation,were proposed for current phase and next phase buses,respectively.The control parameters including minimum green time,green extension time,maximum green time and bus arrival time are calculated.The case studies for this paper were carried out using four consecutive intersections of Huaide Middle Road in Changzhou City.The signal control scheme was designed using the conventional,exclusive bus lane method,the dynamic exclusive bus lane without signal priority method,and the proposed approach,respectively.The authors used the VISSIM simulation platform to evaluate the efficiency of each approach.Results showed that the method of approach can significantly decrease delays caused by social and conventional buses and make up for the negative impact social buses have on the bus rapid transit(BRT)operation,which allows the method to complement the dynamic,exclusive bus lane design.展开更多
With the popularization of terminal devices and services in Internet of things(IoT),it will be a challenge to design a network resource allocation method meeting various QoS requirements and effectively using substrat...With the popularization of terminal devices and services in Internet of things(IoT),it will be a challenge to design a network resource allocation method meeting various QoS requirements and effectively using substrate resources.In this paper,a dynamic network slicing mechanism including virtual network(VN)mapping and VN reconfiguration is proposed to provide network slices for services.Firstly,a service priority model is defined to create queue for resource allocation.Then a slice including Virtual Network Function(VNF)placement and routing with optimal cost is generated by VN mapping.Next,considering temporal variations of service resource requirements,the size of network slice is adjusted dynamically to guarantee resource utilization in VN reconfiguration.Additionally,load balancing factors are designed to make traffic balanced.Simulation results show that dynamic slicing mechanism not only saves 22%and 31%cost than static slicing mechanism with extending shortest path(SS_ESP)and dynamic slicing mechanism with embedding single path(DS_ESP),but also maintains high service acceptance rate.展开更多
The growing use of vehicles with the development of China brings greater pressure on the existing road traffic network. Based on the domestic and international research experiences and the domestic congestion situatio...The growing use of vehicles with the development of China brings greater pressure on the existing road traffic network. Based on the domestic and international research experiences and the domestic congestion situations, this paper selected six indicators that affect the traffic conditions. As each single indicator cannot reflect the detailed traffic quality separately, the dynamic comprehensive evaluation principle is adopted.Then we used the principle of "Variation Driven" to determine the weight vector of each sub-indicator, and established a multi-indicator comprehensive evaluation system through the dynamic weight of each sub-indicator. Finally, the rationality and feasibility of the system is demonstrated by case analysis. This provides a strong theoretical foundation and basis to mitigate traffic congestion.展开更多
Considering the economics and securities for the operation of a power system, this paper presents a new adaptive dynamic programming approach for security-constrained unit commitment (SCUC) problems. In response to t...Considering the economics and securities for the operation of a power system, this paper presents a new adaptive dynamic programming approach for security-constrained unit commitment (SCUC) problems. In response to the “curse of dimension” problem of dynamic programming, the approach solves the Bellman’s equation of SCUC approximately by solving a sequence of simplified single stage optimization problems. An extended sequential truncation technique is proposed to explore the state space of the approach, which is superior to traditional sequential truncation in daily cost for unit commitment. Different test cases from 30 to 300 buses over a 24 h horizon are analyzed. Extensive numerical comparisons show that the proposed approach is capable of obtaining the optimal unit commitment schedules without any network and bus voltage violations, and minimizing the operation cost as well.展开更多
Ecological restoration is considered an important way to mitigate ecosystem degradation and improve regional nature’s contributions to people(NCPs).Ecological planning is a prerequisite for ecological restoration and...Ecological restoration is considered an important way to mitigate ecosystem degradation and improve regional nature’s contributions to people(NCPs).Ecological planning is a prerequisite for ecological restoration and the prevention of future ecological risks.However,few studies have focused on integrating ecological plans within the framework of Sustainable Development Goals(SDGs)and shared socioeconomic pathways(SSPs).In this study,taking the Qinghai‒Xizang Plateau(QXP)as a case,we assessed ecological restoration priorities based on NCPs under various SDGs and SSP scenarios.Specifically,the land use demand was predicted using system dynamics(SD)and cellular automata(CA)models between 2030 and 2060 under SDG-SSP scenarios.In addition,habitat maintenance(NCP1),climate regulation(NCP4),and water quantity regulation(NCP6)were assessed based on the predicted land use.Finally,priority areas for ecological restoration were identified using a zonation model.The results indicated that the grassland,forest,and cultivated areas will increase in the SDGs and SSPs scenarios,respectively.The high-value NCP areas are mainly located in the southeast part of the QXP,accounting for 45.16%of the study area.In addition,the ecological restoration area involves grassland,cultivated and bare land.In the single-objective scenario,NCP1,NCP4,and NCP6 can be improved by 30.29%,28.75%and 25.63%,respectively,through the restoration of 15.33%of the priority areas identified in 2015.When shifting to a multi-objective cooperative optimum,NCP1,NCP4 and NCP6 can be improved 35.79%by restoring 54.96%of the priority areas.This study provides insight into how SDGs and SSPs can contribute to ecological restoration for mitigating ecosystem degradation under SDG-SSP scenarios.展开更多
In the imaging observation system, imaging task scheduling is an important topic. Most scholars study the imaging task scheduling from the perspective of static priority, and only a few from the perspective of dynamic...In the imaging observation system, imaging task scheduling is an important topic. Most scholars study the imaging task scheduling from the perspective of static priority, and only a few from the perspective of dynamic priority. However,the priority of the imaging task is dynamic in actual engineering. To supplement the research on imaging observation, this paper proposes the task priority model, dynamic scheduling strategy and Heuristic algorithm. At first, this paper analyzes the relevant theoretical basis of imaging observation, decomposes the task priority into four parts, including target priority, imaging task priority, track, telemetry & control(TT&C)requirement priority and data transmission requirement priority, summarizes the attribute factors that affect the above four types of priority in detail, and designs the corresponding priority model. Then, this paper takes the emergency tasks scheduling problem as the background, proposes the dynamic scheduling strategy and heuristic algorithm. Finally, the task priority model,dynamic scheduling strategy and heuristic algorithm are verified by experiments.展开更多
A hybrid approach using MLD (mixed logical dynamical) framework to handle infeasibility and constraint prioritization issues in MPC (model predictive control) based on input-output model is introduced. By expressing c...A hybrid approach using MLD (mixed logical dynamical) framework to handle infeasibility and constraint prioritization issues in MPC (model predictive control) based on input-output model is introduced. By expressing constraint priorities as propositional logics and by transforming the propositional logics into inequalities,the infeasibility and constraint prioritization issues are solved in the MPC. Constraints with higher priorities are met first, and then these with lower priorities are satisfied as much as possible. This new approach is illustrated in the control of a heavy oil fractionator-Shell column. The overall control performance has been significantly improved through the infeasibility and control priorities handling.展开更多
To reduce the delay of left-turning buses and improve the traffic efficiency at signalized intersections,a novel variable bus approach lane(VBAL)control method based on bus pre-signals is proposed.This method combines...To reduce the delay of left-turning buses and improve the traffic efficiency at signalized intersections,a novel variable bus approach lane(VBAL)control method based on bus pre-signals is proposed.This method combines the variable lane with the bus priority pre-signal,and realizes the left-turning bus priority without causing great impact on other vehicles.To validate the effectiveness of the method,the VBAL scheme was compared with the single left-turn lane scheme(SLTL)and the double left-turn lane scheme(DLTL).On this basis,the delay change calculation model of left-turning buses and through vehicles were established by the cumulative curve graphic method.The influence of vehicle proportion and green split on the model was studied through sensitivity analysis.The results show that VBAL can reduce the delay of left-turning bus and the increase of through vehicle delay to the greatest extent.Finally,the scheme was applied to a real-world intersection,and the results demonstrate the effectiveness and advantage of the VBAL scheme.展开更多
Indoor biological contamination and HVAC system secondary contamination problems caused wide public concerns. Biological contamination control will be the next step to achieve better IAQ. The most efficient and safe w...Indoor biological contamination and HVAC system secondary contamination problems caused wide public concerns. Biological contamination control will be the next step to achieve better IAQ. The most efficient and safe way to control biological contamination was to limit relative humidity in HVAC system and conditioned environment in the range that is more unsuitable for microorganism to survive. In this paper,by referring to bio-clean project experiences,a system-based humidity priority control manner came into being by lowering outdoor air humidity ratio to eliminate all indoor latent load and using self recirculation units to bear indoor sensible load. Based on the whole-course residue humidity contaminant control concept,dynamic step models for coil and conditioned zone were developed to describe mass and energy conservation and transformation processes. Then,HVAC system and conditioned zone dynamic models were established on LabVIEW+Matlab platform to investigate optimized regulation types,input signatures and control logics. Decoupling between cooling and dehumidification processes can be achieved and a more simplified and stable control system can be acquired by the system-based humidity priority control strategy. Therefore,it was a promising way for controlling biological pollution in buildings in order to achieve better IAQ.展开更多
A brief assessment is provided of both the case against and the case for assigning priority to research on large-scale weather systems （LSWS）. The three-fold case against is based upon： the emergence of new overarc...A brief assessment is provided of both the case against and the case for assigning priority to research on large-scale weather systems （LSWS）. The three-fold case against is based upon： the emergence of new overarching themes in environmental science; the fresh emphasis upon other sub-disciplines of the atmospheric science; and the mature state of research and prediction of LSWS. The case for is also supported by three arguments. First is the assertion that LSWS research should not merely be an integral but a major component of future research related to both the new overarching themes and the other sub-disciplines. Second recent major developments in LSWS research, as epitomized by the paradigm shifts in the prediction strategy for LSWS and the emergence of the potential vorticity perspective, testify to the theme＇s on-going vibrancy. Third the field＇s future development, as exemplified by the new international THORPEX （The Observing System Research and Predictability Experiment） programme, embodies a perceptive dovetailing of intellectually challenging fundamental research with directed application（s） of societal and economic benefit. It is thus inferred that LSWS research, far from being in demise, will feature at the forefront of the new relationship between science and society.展开更多
A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethemet frame, message-oriented dynamic priorit...A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethemet frame, message-oriented dynamic priority mechanism is established. Prioritized medium access control operates under a so-called block mode in event of collisions. High priority messages have a chance to preempt block status incurred by low priority ones. By this means, the new MAC provides a conditional detrministic real time performance beyond a statistical one. Experiments effectiveness and attractiveness of the proposed scheme.Moreover,this new MAC is completely compatible with IEEE802.3 .展开更多
鉴于仓储中心存在诸多不确定的因素提出不确定事件下多仓储机器人动态路径问题(Dynamic Routing Problem of Multi Warehouse Robots under Uncertain Events, DRP-MWR-UE)。该问题考虑了多仓储机器人时变的交通网络、不确定的订单需求...鉴于仓储中心存在诸多不确定的因素提出不确定事件下多仓储机器人动态路径问题(Dynamic Routing Problem of Multi Warehouse Robots under Uncertain Events, DRP-MWR-UE)。该问题考虑了多仓储机器人时变的交通网络、不确定的订单需求。在此基础上,建立了DRP-MWR-UE的双矩阵混合整数规划模型并设计了基于混合动态变邻域搜索算法(Hybrid Dynamic Variable Neighborhood Search, HDVNS)的动态调度策略执行求解。该策略首先将事件判定、分类后由HDVNS进行重调度。为了加快算法动态响应速度和提高求解质量,HDVNS的初始阶段结合了两阶段聚类算法和自适应破坏重组的随机扰动贪婪机制,全局邻域搜索中融入了多种邻域变换策略。最后,通过与对比算法,在两种不确定事件下进行实验。结果表明,HDVNS显著优于其对比算法,是一种求解DRP-MWR-UE的有效方法。展开更多
基金supported by the National Natural Science Foundation of China(7130108161373137)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20130877BK2012833)
文摘According to low earth orbit（LEO） satellite systems with users of different levels, a dynamic channel reservation scheme based on priorities is proposed. Dynamic calculation of the thresholds for reserved channels is the key of this strategy. In order to obtain the optimal thresholds, the traffic is predicted based on the high-speed deterministic movement property of LEO satellites firstly. Then, a channel allocation model based on Markov is established. Finally, the solution of the model is obtained based on the genetic algorithm. Without user location, this strategy effectively reduces handover failures and improves channel utilization by adjusting dynamically the thresholds according to traffic conditions. The simulation results show that the system＇s overall quality of service can be improved by this strategy.
文摘The specific features of the CAN bus is analyzed and the functional performances in the Controller Area Network (CAN) bus system of Wire Harness Assembly Machine (WHAM) is discussed. A reasonable definition of application layer which is not defined in the CAN specification is given for the control system of WHAM. So application layer planning of CAN bus for dynamic priority is presented. With the mechanism of dynamic priority,it becomes easily to find out the error nodes in the CAN bus system of WHAM and realize multi-mode operation.
基金This research was funded by National Natural Science Foundation of China(NSFC),grant number 51678076Hunan Provincial Key Laboratory of Smart Roadway and Cooperative Vehicle-Infrastructure Systems,grant number 2017TP1016.
文摘One problem with the existing dynamic exclusive bus lane strategies is that bus signal priority strategies with multi-phase priority request at intersections are not adequately considered.The principle of bus signal priority level was designed based on the isolated multi-phase structure principle consideration of the bus signal priority,and a new priority approach for the dynamic exclusive bus lane was proposed.Two types of priority strategies,green extension and red truncation,were proposed for current phase and next phase buses,respectively.The control parameters including minimum green time,green extension time,maximum green time and bus arrival time are calculated.The case studies for this paper were carried out using four consecutive intersections of Huaide Middle Road in Changzhou City.The signal control scheme was designed using the conventional,exclusive bus lane method,the dynamic exclusive bus lane without signal priority method,and the proposed approach,respectively.The authors used the VISSIM simulation platform to evaluate the efficiency of each approach.Results showed that the method of approach can significantly decrease delays caused by social and conventional buses and make up for the negative impact social buses have on the bus rapid transit(BRT)operation,which allows the method to complement the dynamic,exclusive bus lane design.
基金This work is supported by National Natural Science Foundation of China(No.61702048).
文摘With the popularization of terminal devices and services in Internet of things(IoT),it will be a challenge to design a network resource allocation method meeting various QoS requirements and effectively using substrate resources.In this paper,a dynamic network slicing mechanism including virtual network(VN)mapping and VN reconfiguration is proposed to provide network slices for services.Firstly,a service priority model is defined to create queue for resource allocation.Then a slice including Virtual Network Function(VNF)placement and routing with optimal cost is generated by VN mapping.Next,considering temporal variations of service resource requirements,the size of network slice is adjusted dynamically to guarantee resource utilization in VN reconfiguration.Additionally,load balancing factors are designed to make traffic balanced.Simulation results show that dynamic slicing mechanism not only saves 22%and 31%cost than static slicing mechanism with extending shortest path(SS_ESP)and dynamic slicing mechanism with embedding single path(DS_ESP),but also maintains high service acceptance rate.
基金Supported by National Natural Science Foundation of China(No.61572523)Philosophy Social Science Project of Tai an City(No.18skx028)+2 种基金Online Course Construction Project of Shandong University of Science and Technology(No.ZXK201829)Excellent Teaching Team of Shan Dong University of Science and Technology(No.JXTD20180509)Technology program of Tai an City(No.2018C0270)
文摘The growing use of vehicles with the development of China brings greater pressure on the existing road traffic network. Based on the domestic and international research experiences and the domestic congestion situations, this paper selected six indicators that affect the traffic conditions. As each single indicator cannot reflect the detailed traffic quality separately, the dynamic comprehensive evaluation principle is adopted.Then we used the principle of "Variation Driven" to determine the weight vector of each sub-indicator, and established a multi-indicator comprehensive evaluation system through the dynamic weight of each sub-indicator. Finally, the rationality and feasibility of the system is demonstrated by case analysis. This provides a strong theoretical foundation and basis to mitigate traffic congestion.
文摘Considering the economics and securities for the operation of a power system, this paper presents a new adaptive dynamic programming approach for security-constrained unit commitment (SCUC) problems. In response to the “curse of dimension” problem of dynamic programming, the approach solves the Bellman’s equation of SCUC approximately by solving a sequence of simplified single stage optimization problems. An extended sequential truncation technique is proposed to explore the state space of the approach, which is superior to traditional sequential truncation in daily cost for unit commitment. Different test cases from 30 to 300 buses over a 24 h horizon are analyzed. Extensive numerical comparisons show that the proposed approach is capable of obtaining the optimal unit commitment schedules without any network and bus voltage violations, and minimizing the operation cost as well.
基金supported by the second Tibetan Plateau Scientific Expedition and Research(Grant No.2019QZKK0405)the National Key Research and Development Project(Grant No.2022YFF1303204)of the National Natural Sciences Foundation of China(Grant No.42271097).
文摘Ecological restoration is considered an important way to mitigate ecosystem degradation and improve regional nature’s contributions to people(NCPs).Ecological planning is a prerequisite for ecological restoration and the prevention of future ecological risks.However,few studies have focused on integrating ecological plans within the framework of Sustainable Development Goals(SDGs)and shared socioeconomic pathways(SSPs).In this study,taking the Qinghai‒Xizang Plateau(QXP)as a case,we assessed ecological restoration priorities based on NCPs under various SDGs and SSP scenarios.Specifically,the land use demand was predicted using system dynamics(SD)and cellular automata(CA)models between 2030 and 2060 under SDG-SSP scenarios.In addition,habitat maintenance(NCP1),climate regulation(NCP4),and water quantity regulation(NCP6)were assessed based on the predicted land use.Finally,priority areas for ecological restoration were identified using a zonation model.The results indicated that the grassland,forest,and cultivated areas will increase in the SDGs and SSPs scenarios,respectively.The high-value NCP areas are mainly located in the southeast part of the QXP,accounting for 45.16%of the study area.In addition,the ecological restoration area involves grassland,cultivated and bare land.In the single-objective scenario,NCP1,NCP4,and NCP6 can be improved by 30.29%,28.75%and 25.63%,respectively,through the restoration of 15.33%of the priority areas identified in 2015.When shifting to a multi-objective cooperative optimum,NCP1,NCP4 and NCP6 can be improved 35.79%by restoring 54.96%of the priority areas.This study provides insight into how SDGs and SSPs can contribute to ecological restoration for mitigating ecosystem degradation under SDG-SSP scenarios.
基金supported by the National Natural Science Foundation of China(61773120,61473301,71501180,71501179,61603400)。
文摘In the imaging observation system, imaging task scheduling is an important topic. Most scholars study the imaging task scheduling from the perspective of static priority, and only a few from the perspective of dynamic priority. However,the priority of the imaging task is dynamic in actual engineering. To supplement the research on imaging observation, this paper proposes the task priority model, dynamic scheduling strategy and Heuristic algorithm. At first, this paper analyzes the relevant theoretical basis of imaging observation, decomposes the task priority into four parts, including target priority, imaging task priority, track, telemetry & control(TT&C)requirement priority and data transmission requirement priority, summarizes the attribute factors that affect the above four types of priority in detail, and designs the corresponding priority model. Then, this paper takes the emergency tasks scheduling problem as the background, proposes the dynamic scheduling strategy and heuristic algorithm. Finally, the task priority model,dynamic scheduling strategy and heuristic algorithm are verified by experiments.
基金Supported by the 973 Program (No. 2002CB312200)National High Tech. Project of China (863/CIMS 2004AA412050).
文摘A hybrid approach using MLD (mixed logical dynamical) framework to handle infeasibility and constraint prioritization issues in MPC (model predictive control) based on input-output model is introduced. By expressing constraint priorities as propositional logics and by transforming the propositional logics into inequalities,the infeasibility and constraint prioritization issues are solved in the MPC. Constraints with higher priorities are met first, and then these with lower priorities are satisfied as much as possible. This new approach is illustrated in the control of a heavy oil fractionator-Shell column. The overall control performance has been significantly improved through the infeasibility and control priorities handling.
基金National Key R&D Program of China(No.2019YFB1600501)Scientific and Technological Developing Project of Jilin Province(No.20190201107JC).
文摘To reduce the delay of left-turning buses and improve the traffic efficiency at signalized intersections,a novel variable bus approach lane(VBAL)control method based on bus pre-signals is proposed.This method combines the variable lane with the bus priority pre-signal,and realizes the left-turning bus priority without causing great impact on other vehicles.To validate the effectiveness of the method,the VBAL scheme was compared with the single left-turn lane scheme(SLTL)and the double left-turn lane scheme(DLTL).On this basis,the delay change calculation model of left-turning buses and through vehicles were established by the cumulative curve graphic method.The influence of vehicle proportion and green split on the model was studied through sensitivity analysis.The results show that VBAL can reduce the delay of left-turning bus and the increase of through vehicle delay to the greatest extent.Finally,the scheme was applied to a real-world intersection,and the results demonstrate the effectiveness and advantage of the VBAL scheme.
基金Project(2006BAJ02A10) supported by the National Key Technologies R & D Program of China
文摘Indoor biological contamination and HVAC system secondary contamination problems caused wide public concerns. Biological contamination control will be the next step to achieve better IAQ. The most efficient and safe way to control biological contamination was to limit relative humidity in HVAC system and conditioned environment in the range that is more unsuitable for microorganism to survive. In this paper,by referring to bio-clean project experiences,a system-based humidity priority control manner came into being by lowering outdoor air humidity ratio to eliminate all indoor latent load and using self recirculation units to bear indoor sensible load. Based on the whole-course residue humidity contaminant control concept,dynamic step models for coil and conditioned zone were developed to describe mass and energy conservation and transformation processes. Then,HVAC system and conditioned zone dynamic models were established on LabVIEW+Matlab platform to investigate optimized regulation types,input signatures and control logics. Decoupling between cooling and dehumidification processes can be achieved and a more simplified and stable control system can be acquired by the system-based humidity priority control strategy. Therefore,it was a promising way for controlling biological pollution in buildings in order to achieve better IAQ.
文摘A brief assessment is provided of both the case against and the case for assigning priority to research on large-scale weather systems （LSWS）. The three-fold case against is based upon： the emergence of new overarching themes in environmental science; the fresh emphasis upon other sub-disciplines of the atmospheric science; and the mature state of research and prediction of LSWS. The case for is also supported by three arguments. First is the assertion that LSWS research should not merely be an integral but a major component of future research related to both the new overarching themes and the other sub-disciplines. Second recent major developments in LSWS research, as epitomized by the paradigm shifts in the prediction strategy for LSWS and the emergence of the potential vorticity perspective, testify to the theme＇s on-going vibrancy. Third the field＇s future development, as exemplified by the new international THORPEX （The Observing System Research and Predictability Experiment） programme, embodies a perceptive dovetailing of intellectually challenging fundamental research with directed application（s） of societal and economic benefit. It is thus inferred that LSWS research, far from being in demise, will feature at the forefront of the new relationship between science and society.
基金This workis partly supported by national 863 project under grant 2002 AA412010 08
文摘A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethemet frame, message-oriented dynamic priority mechanism is established. Prioritized medium access control operates under a so-called block mode in event of collisions. High priority messages have a chance to preempt block status incurred by low priority ones. By this means, the new MAC provides a conditional detrministic real time performance beyond a statistical one. Experiments effectiveness and attractiveness of the proposed scheme.Moreover,this new MAC is completely compatible with IEEE802.3 .
文摘鉴于仓储中心存在诸多不确定的因素提出不确定事件下多仓储机器人动态路径问题(Dynamic Routing Problem of Multi Warehouse Robots under Uncertain Events, DRP-MWR-UE)。该问题考虑了多仓储机器人时变的交通网络、不确定的订单需求。在此基础上,建立了DRP-MWR-UE的双矩阵混合整数规划模型并设计了基于混合动态变邻域搜索算法(Hybrid Dynamic Variable Neighborhood Search, HDVNS)的动态调度策略执行求解。该策略首先将事件判定、分类后由HDVNS进行重调度。为了加快算法动态响应速度和提高求解质量,HDVNS的初始阶段结合了两阶段聚类算法和自适应破坏重组的随机扰动贪婪机制,全局邻域搜索中融入了多种邻域变换策略。最后,通过与对比算法,在两种不确定事件下进行实验。结果表明,HDVNS显著优于其对比算法,是一种求解DRP-MWR-UE的有效方法。
