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
In 1957, the launch of the first artificial satellite ushered in a new era for modern space science. The past 50 years' developments in China's space science have witnessed many major missions, and substantial...In 1957, the launch of the first artificial satellite ushered in a new era for modern space science. The past 50 years' developments in China's space science have witnessed many major missions, and substantial progress has been achieved in space science study, exploration technology as well as experiment technology. Strategic Priority Program on Space Science was officially started in 2011. Through both self-developed space science missions and those with international cooperation,it is expected that the innovative breakthroughs will be realized, leapfrog development of related high-tech will be achieved to establish the important strategic status of space science in national development. To sum up, the implementation of the Strategic Priority Program on Space Science will definitely promote the rapid development of China's space science endeavor, making contributions to China's development and the progress of human civilization.展开更多
The Strategic Priority Program(SPP)on Space Science,which is under the leadership of the Chinese Academy of Sciences(CAS),has established China’s space science satellite series from scratch.A number of major scientif...The Strategic Priority Program(SPP)on Space Science,which is under the leadership of the Chinese Academy of Sciences(CAS),has established China’s space science satellite series from scratch.A number of major scientific achievements have been made by the first phase of the Program(SPPⅠ),while SPPⅡhas been currently being implemented.The future development of space science needs urgent top-level planning and advanced layout to clarify the overall goal and investment portfolio from 2025 to 2030.We will briefly introduce the initiative and possible space science missions of SPPⅢ,including the preparatory work which already started in July 2021.Following the effective administrative tradition since SPPⅠ,National Space Science Center(NSSC,CAS)is responsible for the whole procedure,including soliciting,assessment,and implementation of SPPⅢ.Brief information on the 13 candidate missions will be described,including missions in the fields of astronomy&astrophysics,exoplanets,heliophysics and planetary&Earth science,respectively.展开更多
In May 2018,the second phase of the Strategic Priority Program on Space Science(SPP II)was officially approved by the Chinese Academy of Sciences,in view of the significant scientific achievements of the first phase o...In May 2018,the second phase of the Strategic Priority Program on Space Science(SPP II)was officially approved by the Chinese Academy of Sciences,in view of the significant scientific achievements of the first phase of the Strategic Priority Program on Space Science(SPP I)which includes 4 space science missions:the Dark Matter Particle Explorer(DAMPE),ShiJian-10(SJ-10),Quantum Experiments at Space Scale(QUESS)and Hard X-ray Modulation Telescope(HXMT).Aiming to address fundamental scientific questions,SPP II focuses on two major themes:How the universe and life originate and evolve and What is the relationship between the solar system and human beings.In areas that Chinese scientists have advantages,new space science missions including Graviational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM),the Advanced space-based Solar Observatory(ASO-S),the Einstein Probe(EP),and Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)have been approved in the framework of SPP II.This paper presents the research highlights of the SPP I,introduces the recent progress of SPP II,and puts forward the prospects for future development.展开更多
Food security,food safety and environmental protection are major livelihood issues in front of the Chinese people.The priorities of the three are different,and there is mutually dependent and contradictory relationshi...Food security,food safety and environmental protection are major livelihood issues in front of the Chinese people.The priorities of the three are different,and there is mutually dependent and contradictory relationship among them.Facing the triple pressures of food security,food safety,and environmental protection,this paper analyzes the priority of the three from the historical development,then further analyzes the interaction between food security,food safety and environmental protection and finally puts forward the healthy development of food security,food safety and environmental protection,and the proper settlement of the three problems.展开更多
Guaranteed quality of service(QoS) support has been an open issue of distributed wireless networks for years. The IEEE802.11 e provides a valuable method for this purpose. However, it could only provide service differ...Guaranteed quality of service(QoS) support has been an open issue of distributed wireless networks for years. The IEEE802.11 e provides a valuable method for this purpose. However, it could only provide service differentiation, rather than service guarantee, for multi-priority traffic. Many studies have tried to improve its QoS ability, but still leave some problems. This paper investigates these problems and proposes a scheme called the priority access based on busy tone(PABT) to improve the Qo S performance. To guarantee the priority channel access, this scheme uses an in-band busy tone to limit the transmission of lower-priority traffic when higher-priority traffic has packets to send. Based on that, it also optimizes the contention window tuning according to the flows number of each traffic type individually, in order to improve the throughput as well as the traffic capacity. Simulation results show that the proposed scheme significantly improves the real-time traffic capacity, throughput, delay, fairness and packet loss rate.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
In modern data centers, because of the deadline- agnostic congestion control in transmission control protocol （TCP）, many deadline-sensitive flows can not finish before their deadlines. Therefore, providing a higher...In modern data centers, because of the deadline- agnostic congestion control in transmission control protocol （TCP）, many deadline-sensitive flows can not finish before their deadlines. Therefore, providing a higher deadline meeting ratio becomes a critical challenge in the typical online data intensive （OLDI） ap- plications of data center networks （DCNs）. However, a problem named as priority synchronization is found in this paper, which de- creases the deadline meeting ratio badly. To solve this problem, we propose a priority probability deceleration （P2D） deadline-aware TCP. By using the novel probabilistic deceleration, p2D prevents the priority synchronization problem. Simulation results show that P2D increases the deadline meeting ratio by 20% compared with D2TCP.展开更多
A new two-stage soft real-time scheduling algorithm based on priority table was proposed for task dispatch and selection in cluster systems with inaccurate parameters. The inaccurate characteristics of the system were...A new two-stage soft real-time scheduling algorithm based on priority table was proposed for task dispatch and selection in cluster systems with inaccurate parameters. The inaccurate characteristics of the system were modeled through probability analysis. By taking into account the multiple important system parameters, including task deadline, priority, session integrity and memory access locality, the algorithm is expected to achieve high quality of service. Lots of simulation results collected under different load conditions demonstrate that the algorithm can not only effectively overcome the inaccuracy of the system state, but also optimize the task rejected ratio, value realized ratio, differentiated service guaranteed ratio, and session integrity ensured ratio with the average improvement of 3.5%, 5.8%, 7.6% and 5. 5%, respectively. Compared with many existing schemes that cannen deal with the inaccurate parameters of the system, the proposed scheme can achieve the best system performance by carefully adjusting scheduling probability. The algorithm is expected to be promising in systems with soft real-time scheduling requirement such as E-commerce applications.展开更多
An approach is proposed to solve the problem how to obtain the priorities from interval fuzzy preference relations. Firstly, another expression of interval numbers is given. Then, some basic definitions on consistency...An approach is proposed to solve the problem how to obtain the priorities from interval fuzzy preference relations. Firstly, another expression of interval numbers is given. Then, some basic definitions on consistency and weak transitivity of real and interval fuzzy preference relations are described. Based on these definitions, a two-phase process for determining the priorities from interval fuzzy preference relations is presented. Finally, two exam- ples are used to illustrate the use of the proposed approach.展开更多
The uncertain multi-attribute decision-making problems because of the information about attribute weights being known partly, and the decision maker＇s preference information on alternatives taking the form of interva...The uncertain multi-attribute decision-making problems because of the information about attribute weights being known partly, and the decision maker＇s preference information on alternatives taking the form of interval numbers complementary to the judgment matrix, are investigated. First, the decision-making information, based on the subjective uncertain complementary preference matrix on alternatives is made uniform by using a translation function, and then an objective programming model is established. The attribute weights are obtained by solving the model, thus the overall values of the alternatives are gained by using the additive weighting method. Second, the alternatives are ranked, by using the continuous ordered weighted averaging （C-OWA） operator. A new approach to the uncertain multi-attribute decision-making problems, with uncertain preference information on alternatives is proposed. It is characterized by simple operations and can be easily implemented on a computer. Finally, a practical example is illustrated to show the feasibility and availability of the developed method.展开更多
The problem of scheduling radar dwells in multifunction phased array radar systems is addressed. A novel dwell scheduling algorithm is proposed. The whole scheduling process is based on an online pulse interleaving te...The problem of scheduling radar dwells in multifunction phased array radar systems is addressed. A novel dwell scheduling algorithm is proposed. The whole scheduling process is based on an online pulse interleaving technique. It takes the system timing and energy constraints into account. In order to adapt the dynamic task load, the algorithm considers both the priorities and deadlines of tasks. The simulation results demonstrate that compared with the conventional adaptive dwell scheduling algorithm, the proposed one can improve the task drop rate and system resource utility effectively.展开更多
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
Quantum Science Satellite is one of the first five space science missions, slated for launch in the framework of Chinese Academy of Sciences(CAS) Strategic Priority Research Program on space science. The project aims ...Quantum Science Satellite is one of the first five space science missions, slated for launch in the framework of Chinese Academy of Sciences(CAS) Strategic Priority Research Program on space science. The project aims to establish a space platform with long-distance satellite and ground quantum channel, and carry out a series of tests about fundamental quantum principles and protocols in space-based large scale. The satellite will be launched at Jiuquan and on orbit for 2 years. The orbit will be circular and Sun-synchronous with an altitude of 600 km. It crosses the descending node at 00:00 LT. The satellite is under early prototype development currently.展开更多
The missile-tracked priority assessment for the early warning system monitoring multi-missile very well, is the first task to defend them and useful to perform optimally the sensor-to-missile assignment. The problem o...The missile-tracked priority assessment for the early warning system monitoring multi-missile very well, is the first task to defend them and useful to perform optimally the sensor-to-missile assignment. The problem of the missile-tracked priority assessment is of incomplete information, of multi-attribute and dynamic. To solve the dificult problem, the index system, which includes six classification indices, is established by means of reducing the target＇s primary information which the early warning system focuses on. The lack of some attributes values, which is caused by the incomplete information, is handled by the approach： first classifying each attribute as unknown one or known one, and then subdividing the latter, last using the expectation and the information entropy if the attribute is known but uncertain. With a view of reality, nine qualitative evaluation criteria are given. Based on them each index is quantified by the eigenvector method. And then based on the improved technique for order preference by similarity to ideal solution （TOPSIS）, the targets-tracked priorities are assessed and sorted by an evaluation function from three aspects： 1） the quantity of the available information, 2） the affirmative or accurate degree of the available information, 3） the classification or trait of the available information.展开更多
In many Chinese cities,motorized vehicles （M-vehicles） move slowly at intersections due to the interference of a large number of non-motorized vehicles （NM-vehicles）.The slow movement makes a part of M-vehicles fa...In many Chinese cities,motorized vehicles （M-vehicles） move slowly at intersections due to the interference of a large number of non-motorized vehicles （NM-vehicles）.The slow movement makes a part of M-vehicles fail to leave intersections timely after the traffic signal tums red,and thereby conflicts between vehicles from two directions occur.The phenomenon was analyzed graphically by using the cumulative vehicle curve.Delays in three cases were modeled and compared：NM-vehicle priorities and M-vehicle priorities with all-red intervals unable to release all vehicles,and longer all-red intervals ensuring release all vehicles.Marginal delays caused by two illegal behaviors that occasionally happened in mixed traffic intersections were also investigated.It is concluded that increasing the speed of M-vehicles leaving intersections and postponing the entering of NM-vehicles are the keys in mathematics,although they are uneasy in disordered mixed traffic intersections due to a dilemma between efficiency and orders in reality.The results could provide implications for the traffic management in the cities maintaining a large number of M-and NM-vehicles.展开更多
The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (...The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (RT) user,minimal rate for each non-real time (NRT) user,maximal bits and power for each subcarrier in each orthogonal frequency division multiplexing (OFDM) symbol. An algorithm of resource dynamic allocation in the first OFDM symbol of each frame and resource optimal adjustment in the latter OFDM symbol of each frame was proposed. In the first OFDM symbol of every frame,resource is firstly assigned for RT users so as to minimize their total used power until satisfying their fixed rates; secondly the remainder resource of power and subcarriers are assigned for NRT users so as to minimize their total used power until satisfying their minimal rates also; lastly the remainder resource is again assigned for NRT users according to the proportional fairness strategy so as to maximize their total assigning rate. In the latter OFDM symbol of each frame,bits are swapped and power is adjusted for every user based on the resource allocation results of anterior OFDM symbol. The algorithm is tested in the typical power-line channel scenarios and the simulation results indicate that the proposed algorithm has better performances than the classical multi-user resource allocation algorithms and it realizes the multiple aims of multi-user multi-server resource allocation for power-line communication systems.展开更多
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.
文摘In 1957, the launch of the first artificial satellite ushered in a new era for modern space science. The past 50 years' developments in China's space science have witnessed many major missions, and substantial progress has been achieved in space science study, exploration technology as well as experiment technology. Strategic Priority Program on Space Science was officially started in 2011. Through both self-developed space science missions and those with international cooperation,it is expected that the innovative breakthroughs will be realized, leapfrog development of related high-tech will be achieved to establish the important strategic status of space science in national development. To sum up, the implementation of the Strategic Priority Program on Space Science will definitely promote the rapid development of China's space science endeavor, making contributions to China's development and the progress of human civilization.
基金Supported by Strategic Priority Research Program of the Chinese Academy of Sciences(XDA15060102)。
文摘The Strategic Priority Program(SPP)on Space Science,which is under the leadership of the Chinese Academy of Sciences(CAS),has established China’s space science satellite series from scratch.A number of major scientific achievements have been made by the first phase of the Program(SPPⅠ),while SPPⅡhas been currently being implemented.The future development of space science needs urgent top-level planning and advanced layout to clarify the overall goal and investment portfolio from 2025 to 2030.We will briefly introduce the initiative and possible space science missions of SPPⅢ,including the preparatory work which already started in July 2021.Following the effective administrative tradition since SPPⅠ,National Space Science Center(NSSC,CAS)is responsible for the whole procedure,including soliciting,assessment,and implementation of SPPⅢ.Brief information on the 13 candidate missions will be described,including missions in the fields of astronomy&astrophysics,exoplanets,heliophysics and planetary&Earth science,respectively.
基金Supported by the Strategic Priority Program on Space Science of the Chinese Academy of Sciences(XDA15000000)。
文摘In May 2018,the second phase of the Strategic Priority Program on Space Science(SPP II)was officially approved by the Chinese Academy of Sciences,in view of the significant scientific achievements of the first phase of the Strategic Priority Program on Space Science(SPP I)which includes 4 space science missions:the Dark Matter Particle Explorer(DAMPE),ShiJian-10(SJ-10),Quantum Experiments at Space Scale(QUESS)and Hard X-ray Modulation Telescope(HXMT).Aiming to address fundamental scientific questions,SPP II focuses on two major themes:How the universe and life originate and evolve and What is the relationship between the solar system and human beings.In areas that Chinese scientists have advantages,new space science missions including Graviational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM),the Advanced space-based Solar Observatory(ASO-S),the Einstein Probe(EP),and Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)have been approved in the framework of SPP II.This paper presents the research highlights of the SPP I,introduces the recent progress of SPP II,and puts forward the prospects for future development.
基金the research fruits of"A Study of the Public Interest Litigation and Security Mechanism for the Quality and Safety of Agricultural Products"(15BGL135),a general project granted by the National Social Sciences Planning Office.
文摘Food security,food safety and environmental protection are major livelihood issues in front of the Chinese people.The priorities of the three are different,and there is mutually dependent and contradictory relationship among them.Facing the triple pressures of food security,food safety,and environmental protection,this paper analyzes the priority of the three from the historical development,then further analyzes the interaction between food security,food safety and environmental protection and finally puts forward the healthy development of food security,food safety and environmental protection,and the proper settlement of the three problems.
基金supported by the Special Fund for National Defense Technology Innovation(18-163-11-ZT-003-027-01)
文摘Guaranteed quality of service(QoS) support has been an open issue of distributed wireless networks for years. The IEEE802.11 e provides a valuable method for this purpose. However, it could only provide service differentiation, rather than service guarantee, for multi-priority traffic. Many studies have tried to improve its QoS ability, but still leave some problems. This paper investigates these problems and proposes a scheme called the priority access based on busy tone(PABT) to improve the Qo S performance. To guarantee the priority channel access, this scheme uses an in-band busy tone to limit the transmission of lower-priority traffic when higher-priority traffic has packets to send. Based on that, it also optimizes the contention window tuning according to the flows number of each traffic type individually, in order to improve the throughput as well as the traffic capacity. Simulation results show that the proposed scheme significantly improves the real-time traffic capacity, throughput, delay, fairness and packet loss rate.
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.
基金supported by the National Natural Science Foundation of China(611630606110320461462007)
文摘In modern data centers, because of the deadline- agnostic congestion control in transmission control protocol （TCP）, many deadline-sensitive flows can not finish before their deadlines. Therefore, providing a higher deadline meeting ratio becomes a critical challenge in the typical online data intensive （OLDI） ap- plications of data center networks （DCNs）. However, a problem named as priority synchronization is found in this paper, which de- creases the deadline meeting ratio badly. To solve this problem, we propose a priority probability deceleration （P2D） deadline-aware TCP. By using the novel probabilistic deceleration, p2D prevents the priority synchronization problem. Simulation results show that P2D increases the deadline meeting ratio by 20% compared with D2TCP.
基金Project(60573127) supported by the National Natural Science Foundation of China project(05JJ40131) supported by theNatural Science Foundation of Hunan Province
文摘A new two-stage soft real-time scheduling algorithm based on priority table was proposed for task dispatch and selection in cluster systems with inaccurate parameters. The inaccurate characteristics of the system were modeled through probability analysis. By taking into account the multiple important system parameters, including task deadline, priority, session integrity and memory access locality, the algorithm is expected to achieve high quality of service. Lots of simulation results collected under different load conditions demonstrate that the algorithm can not only effectively overcome the inaccuracy of the system state, but also optimize the task rejected ratio, value realized ratio, differentiated service guaranteed ratio, and session integrity ensured ratio with the average improvement of 3.5%, 5.8%, 7.6% and 5. 5%, respectively. Compared with many existing schemes that cannen deal with the inaccurate parameters of the system, the proposed scheme can achieve the best system performance by carefully adjusting scheduling probability. The algorithm is expected to be promising in systems with soft real-time scheduling requirement such as E-commerce applications.
基金supported by the National Natural Science Foundation for Excellent Innovation Research Group of China (70721001)the National Natural Science Foundation of China (90924016)Fundamental Research Fund for Northeastern University (N090606001)
文摘An approach is proposed to solve the problem how to obtain the priorities from interval fuzzy preference relations. Firstly, another expression of interval numbers is given. Then, some basic definitions on consistency and weak transitivity of real and interval fuzzy preference relations are described. Based on these definitions, a two-phase process for determining the priorities from interval fuzzy preference relations is presented. Finally, two exam- ples are used to illustrate the use of the proposed approach.
文摘The uncertain multi-attribute decision-making problems because of the information about attribute weights being known partly, and the decision maker＇s preference information on alternatives taking the form of interval numbers complementary to the judgment matrix, are investigated. First, the decision-making information, based on the subjective uncertain complementary preference matrix on alternatives is made uniform by using a translation function, and then an objective programming model is established. The attribute weights are obtained by solving the model, thus the overall values of the alternatives are gained by using the additive weighting method. Second, the alternatives are ranked, by using the continuous ordered weighted averaging （C-OWA） operator. A new approach to the uncertain multi-attribute decision-making problems, with uncertain preference information on alternatives is proposed. It is characterized by simple operations and can be easily implemented on a computer. Finally, a practical example is illustrated to show the feasibility and availability of the developed method.
文摘The problem of scheduling radar dwells in multifunction phased array radar systems is addressed. A novel dwell scheduling algorithm is proposed. The whole scheduling process is based on an online pulse interleaving technique. It takes the system timing and energy constraints into account. In order to adapt the dynamic task load, the algorithm considers both the priorities and deadlines of tasks. The simulation results demonstrate that compared with the conventional adaptive dwell scheduling algorithm, the proposed one can improve the task drop rate and system resource utility effectively.
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Quantum Science Satellite is one of the first five space science missions, slated for launch in the framework of Chinese Academy of Sciences(CAS) Strategic Priority Research Program on space science. The project aims to establish a space platform with long-distance satellite and ground quantum channel, and carry out a series of tests about fundamental quantum principles and protocols in space-based large scale. The satellite will be launched at Jiuquan and on orbit for 2 years. The orbit will be circular and Sun-synchronous with an altitude of 600 km. It crosses the descending node at 00:00 LT. The satellite is under early prototype development currently.
基金supported by the National Ministry Foundation for the Pre-research
文摘The missile-tracked priority assessment for the early warning system monitoring multi-missile very well, is the first task to defend them and useful to perform optimally the sensor-to-missile assignment. The problem of the missile-tracked priority assessment is of incomplete information, of multi-attribute and dynamic. To solve the dificult problem, the index system, which includes six classification indices, is established by means of reducing the target＇s primary information which the early warning system focuses on. The lack of some attributes values, which is caused by the incomplete information, is handled by the approach： first classifying each attribute as unknown one or known one, and then subdividing the latter, last using the expectation and the information entropy if the attribute is known but uncertain. With a view of reality, nine qualitative evaluation criteria are given. Based on them each index is quantified by the eigenvector method. And then based on the improved technique for order preference by similarity to ideal solution （TOPSIS）, the targets-tracked priorities are assessed and sorted by an evaluation function from three aspects： 1） the quantity of the available information, 2） the affirmative or accurate degree of the available information, 3） the classification or trait of the available information.
基金Project(2012CB725403)supported by the National Key Research Program of ChinaProject(71131001)supported by the National Natural Science Foundation of ChinaProject(2012JBM064)supported by the Fundamental Research Funds for the Central Universities of China
文摘In many Chinese cities,motorized vehicles （M-vehicles） move slowly at intersections due to the interference of a large number of non-motorized vehicles （NM-vehicles）.The slow movement makes a part of M-vehicles fail to leave intersections timely after the traffic signal tums red,and thereby conflicts between vehicles from two directions occur.The phenomenon was analyzed graphically by using the cumulative vehicle curve.Delays in three cases were modeled and compared：NM-vehicle priorities and M-vehicle priorities with all-red intervals unable to release all vehicles,and longer all-red intervals ensuring release all vehicles.Marginal delays caused by two illegal behaviors that occasionally happened in mixed traffic intersections were also investigated.It is concluded that increasing the speed of M-vehicles leaving intersections and postponing the entering of NM-vehicles are the keys in mathematics,although they are uneasy in disordered mixed traffic intersections due to a dilemma between efficiency and orders in reality.The results could provide implications for the traffic management in the cities maintaining a large number of M-and NM-vehicles.
基金Projects(51007021, 60402004) supported by the National Natural Science Foundation of China
文摘The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (RT) user,minimal rate for each non-real time (NRT) user,maximal bits and power for each subcarrier in each orthogonal frequency division multiplexing (OFDM) symbol. An algorithm of resource dynamic allocation in the first OFDM symbol of each frame and resource optimal adjustment in the latter OFDM symbol of each frame was proposed. In the first OFDM symbol of every frame,resource is firstly assigned for RT users so as to minimize their total used power until satisfying their fixed rates; secondly the remainder resource of power and subcarriers are assigned for NRT users so as to minimize their total used power until satisfying their minimal rates also; lastly the remainder resource is again assigned for NRT users according to the proportional fairness strategy so as to maximize their total assigning rate. In the latter OFDM symbol of each frame,bits are swapped and power is adjusted for every user based on the resource allocation results of anterior OFDM symbol. The algorithm is tested in the typical power-line channel scenarios and the simulation results indicate that the proposed algorithm has better performances than the classical multi-user resource allocation algorithms and it realizes the multiple aims of multi-user multi-server resource allocation for power-line communication systems.
