The relationship between physical activity time,openness and depression symptoms among adolescents is a cutting-edge research direction in the field,yet it remains unclear.This study is based on a sample of 7924 stude...The relationship between physical activity time,openness and depression symptoms among adolescents is a cutting-edge research direction in the field,yet it remains unclear.This study is based on a sample of 7924 students from a nationally representative China Education Panel Survey database and examines the bidirectional relationships between physical activity time,openness and depression symptoms among Chinese adolescents.Descriptive analysis showed that during the 7th and 8th grades,the average physical activity time decreased to less than one hour per day,accompanied by a decreasing trend in openness and a slight worsening in depression symptoms.Correlation analysis showed a significant negative correlation between physical activity time and depression symptoms,a significant positive correlation between physical activity time and openness,and a significant negative correlation between depression symptoms and openness.The results from cross-lagged models indicated a bidirectional relationship between physical activity time and openness,with physical activity time significantly positively predicting openness in the following year and openness significantly positively predicting physical activity time in the following year.In addition,depression symptoms had a unidirectional negative predictive effect on openness.The conclusions provide empirical evidence for education administration and schools to promote the physical and mental health development of adolescents worldwide.展开更多
Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim...Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim of evaluating the performance of an FSO communication system and extending the line-of-sight transmission distance,we propose an unmanned aerial vehicle(UAV)-assisted dual-hop FSO communication system equipped with amplifyand-forward protocol at the relay node.Specifically,we consider impairments of atmospheric absorption,pointing errors,atmospheric turbulence,and link interruptions due to angle-of-arrival fluctuations in the relay system.The Gamma-Gamma and Malaga distributions are used to model the influence of atmospheric turbulence on the source-to-UAV and UAVto-destination links,respectively.We derive closedform expressions of the probability density function(PDF)and cumulative distribution function(CDF)for the proposed communication system,in terms of the Meijer-G function.Based on the precise PDF and CDF,analytical expressions for the outage probability,average bit error rate,and ergodic capacity are proposed with the aid of the extended generalized bivariate Fox’s H function.Finally,we show that there is a match between the analytical results and numerical results,and we analyze the influence of the system and channel parameters on the performance.展开更多
Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA stra...Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA strategy, which might not be suited to the dynamic network environment. In this paper, we propose a multi-strategy DSA(MS-DSA) system, where the primary and the secondary system share spectrum resources with multiple DSA strategies simultaneously. To analyze the performance of the proposed MS-DSA system, we model it as a continuous-time Markov chain(CTMC) and derive the expressions to compute the corresponding performance metrics. Based on this, we define a utility function involving the concerns of effective throughput, interference quantity on primary users, and spectrum leasing cost. Two optimization schemes, named as spectrum allocation and false alarm probability selection, are proposed to maximize the utility function. Finally, numerical simulations are provided to validate our analysis and demonstrate that the performance can be significantly improved caused by virtues of the proposed MS-DSA system.展开更多
Radio spectrum has become a rare resource due to the rapid development of wireless communication technique. Cognitive radio is one of important techniques to deal with this radio spectrum problem. But the resource all...Radio spectrum has become a rare resource due to the rapid development of wireless communication technique. Cognitive radio is one of important techniques to deal with this radio spectrum problem. But the resource allocation in cognitive radio also has its own issues, such as the flexibility of the allocation algorithm, the performance of resource allocation, and so on. In order to increase the flexibility of the allocation algorithm for cognitive radio, more and more researches are focusing on the evolutionary algorithms, such as genetic algorithm(GA), particle swarm optimization(PSO). Evolutionary algorithm can greatly improve the flexibility of the allocation algorithm for cognitive radio system in different communication scenarios, but the performances are relatively lower than the original mathematical methods. So in this paper, we proposed an adaptive resource allocation algorithm based on modified PSO for cognitive radio system to solve these problems. Modified particle swarm optimization(Modified PSO) has both genetic algorithm(GA) and particle swarm optimization(PSO)’s updating processes which makes this modified PSO overcame PSO’s own disadvantages and keep advantages. Simulation results showed our proposed algorithm has enough flexibility to meet cognitive radio systems’ requirements, and also has a better performance than original PSO.展开更多
Mobile edge caching technology is gaining more and more attention because it can effectively improve the Quality of Experience (QoE) of users and reduce backhaul burden. This paper aims to improve the utility of mobil...Mobile edge caching technology is gaining more and more attention because it can effectively improve the Quality of Experience (QoE) of users and reduce backhaul burden. This paper aims to improve the utility of mobile edge caching technology from the perspectie of caching resource management by examining a network composed of one operator, multiple users and Content Providers (CPs). The caching resource management model is constructed on the premise of fully considering the QoE of users and the servicing capability of the Base Station (BS). In order to create the best caching resource allocation scheme, the original problem is transformed into a multi-leader multi-follower Stackelberg game model through the analysis of the system model. The strategy combinations and the utility functions of players are analyzed. The existence and uniqueness of the Nash Equilibrium (NE) solution are also analyzed and proved. The optimal strategy combinations and the best responses are deduced in detail. Simulation results and analysis show that the proposed model and algorithm can achieve the optimal allocation of caching resource and improve the QoE of users.展开更多
This work focuses on an unmanned aerial vehicle(UAV)-enabled mobile edge computing(MEC) system based on device-to-device(D2D) communication. In this system, the UAV exhibits caching,computing and relaying capabilities...This work focuses on an unmanned aerial vehicle(UAV)-enabled mobile edge computing(MEC) system based on device-to-device(D2D) communication. In this system, the UAV exhibits caching,computing and relaying capabilities to periodically provide specific service to cellular users and D2D receiver nodes in the appointed time slot. Besides, the D2D transmitter can provide additional caching services to D2D receiver to reduce the pressure of the UAV. Note that communication between multi-type nodes is mutually restricted and different links share spectrum resources. To achieve an improved balance between different types of node, we aim to maximize the overall energy efficiency while satisfying the quality-of-service requirements of the cellular nodes.To address this problem, we propose an alternating iteration algorithm to jointly optimize the scheduling strategies of the user, transmitting power of the UAV and D2D-TX nodes, and UAV trajectory. The successive convex approximation, penalty function, and Dinkelbach method are employed to transform the original problem into a group of solvable subproblems and the convergence of the method is proved. Simulation results show that the proposed scheme performs better than other benchmark algorithms, particularly in terms of balancing the tradeoff between minimizing UAV energy consumption and maximizing throughput.展开更多
Along with the swift growth of communication services,various networks have undergone multidimensional technical evolution,e.g.high transmission speed and large bandwidth for ground cellular network,high mobility for ...Along with the swift growth of communication services,various networks have undergone multidimensional technical evolution,e.g.high transmission speed and large bandwidth for ground cellular network,high mobility for aviation network,and wide-area coverage for satellite network.As the industry demands for joint operation arise,an integrated space-air-ground collaboration network will be formed.展开更多
Since the first space probe flew to the Moon in 1959,over 200 deep-space exploration missions have already been carried out on the eight planets,various asteroids and comets in the solar system.Amount of deepspace sci...Since the first space probe flew to the Moon in 1959,over 200 deep-space exploration missions have already been carried out on the eight planets,various asteroids and comets in the solar system.Amount of deepspace scientific experiments promoted people to understand about the origin and evolution of the universe.展开更多
Mobile Edge Computing(MEC)is a promising solution to tackle the upcoming computing tsunami in 5G/6G era by effectively utilizing the idle resource at the mobile edge.In this work,a multi⁃hop D2D⁃enabled MEC scenario w...Mobile Edge Computing(MEC)is a promising solution to tackle the upcoming computing tsunami in 5G/6G era by effectively utilizing the idle resource at the mobile edge.In this work,a multi⁃hop D2D⁃enabled MEC scenario was studied,where mobile devices at network edge connect and share resources with each other via multi⁃hop D2D.The research focus was on the micro⁃task scheduling problem in the multi⁃hop D2D⁃enabled MEC system,where each task was divided into multiple sequential micro⁃tasks,such as data downloading micro⁃task,data processing micro⁃task,and data uploading micro⁃task,according to their functionalities as well as resource requirements.A joint Task Failure Probability and Energy Consumption Minimization(TFP⁃ECM)problem was proposed,aiming at minimizing the task failure probability and the energy consumption jointly.To solve the problem,several linearization methods were proposed to relax the constraints and convert the original problem into an integer linear programming(ILP).Simulation results show that the proposed solution outperformed the existing solutions(with indivisible tasks or without resource sharing)in terms of both total cost and task failure probability.展开更多
In order to expand the sources of raw materials for edible fungus cultivation, reduce the use of wood, and realize the harmless treatment and efficient utilization of bamboo sawdust, bamboo sawdust was used to partial...In order to expand the sources of raw materials for edible fungus cultivation, reduce the use of wood, and realize the harmless treatment and efficient utilization of bamboo sawdust, bamboo sawdust was used to partially replace the broad-leaved wood sawdust in the conventional formula, and the growth of Ganoderma lucidum and Stropharia rugosoannulata mycelia in a large test tube in different matrix formulas was studied. The results show that the mycelia of the two edible fungi could grow normally in the matrices with bamboo sawdust;the growth of the mycelia in various formulas was different, and the performances of different strains of the same species were also different. Compared with the conventional formula, the suitable substitution amount of bamboo sawdust for the G. lucidum strains was 30%-45%, and that for S. rugosoannulata strains was 16%-32%.展开更多
Stropharia rugosoannulata is a straw rotting edible fungus that has developed rapidly in recent years.In the process of cultivation,key technologies have a huge impact on its yield.The key techniques for the cultivati...Stropharia rugosoannulata is a straw rotting edible fungus that has developed rapidly in recent years.In the process of cultivation,key technologies have a huge impact on its yield.The key techniques for the cultivation conditions and modes of S.rugosoannulata were summerized to promote the realization of stable and high yield of S.rugosoannulata.展开更多
The increasing demands in terms of high data rate and quality of services over the hybrid satellite-terrestrial relay networks(HSTRN)have pushed for the development of millimeter-wave(mmWave)band high-throughput satel...The increasing demands in terms of high data rate and quality of services over the hybrid satellite-terrestrial relay networks(HSTRN)have pushed for the development of millimeter-wave(mmWave)band high-throughput satellites(HTS)with multibeams.The next generation of mmWave multibeam HTS communication systems(HTSCS)is viewed as the backbone network to enhance the throughput of the HSTRN.The article first investigates the basic backbone topology architecture of HTSCS,and an M-state Markov channel for the Ka/Q/V band mmWave systems is reviewed.Then,we propose a long-term optimal power allocation scheme over two in-dependent and identical spot beams based on the partially observable Markov decision process(POMDP),which can partly mitigate the negative effects of severe weather conditions.The key conditions for selecting the optimal power allocation action in the multibeam HTSCS are given.Simulation results show that our POMDP-based power allocation scheme can enhance the long-term throughput of the HTSCS.展开更多
Unlimited and seamless coverage as well as ultra-reliable and low-latency communications are vital for connected vehicles,in particular for new use cases like autonomous driving and vehicle platooning.In this paper,we...Unlimited and seamless coverage as well as ultra-reliable and low-latency communications are vital for connected vehicles,in particular for new use cases like autonomous driving and vehicle platooning.In this paper,we propose a novel Space-Air-Ground integrated vehicular network(SAGiven)architecture to gracefully integrate the multi-dimensional and multi-scale context-information and network resources from satellites,High-Altitude Platform stations(HAPs),low-altitude Unmanned Aerial Vehicles(UAVs),and terrestrial cellular communication systems.One of the key features of the SAGiven is the reconfigurability of heterogeneous network functions as well as network resources.We first give a comprehensive review of the key challenges of this new architecture and then provide some up-to-date solutions on those challenges.Specifically,the solutions will cover the following topics:(1)space-air-ground integrated network reconfiguration under dynamic space resources constraints;(2)multi-dimensional sensing and efficient integration of multi-dimensional context information;(3)real-time,reliable,and secure communications among vehicles and between vehicles and the SAGiven platform;and(4)a holistic integration and demonstration of the SAGiven.Finally,it is concluded that the SAGiven can play a key role in future autonomous driving and Internet-of-Vehicles applications.展开更多
Appropriate traffic coordination at road intersections plays a crucial part in modern intelligent transportation systems.In this paper,we first try to extend the traditional single collision-set coordination strategy ...Appropriate traffic coordination at road intersections plays a crucial part in modern intelligent transportation systems.In this paper,we first try to extend the traditional single collision-set coordination strategy to multiple-collision-set strategies,by which the traffic throughput can be significantly improved.Unlike the existing centralized coordination methods,two low complexity coordination methods are proposed based on the multi-agents Q-learning frameworks.Numerical results show that,the proposed high throughput strategies are able to provide safe and efficient traffic coordination.Meanwhile,since only local information is required,the coordination complexity can be reduced,which is attractive in highly dynamic real time scenarios.展开更多
Reliable and efficient overtaking maneuvers are important and challenging for autonomous vehicles.Higher precision position information is thus required,rather than that traditional global navigation satellite systems...Reliable and efficient overtaking maneuvers are important and challenging for autonomous vehicles.Higher precision position information is thus required,rather than that traditional global navigation satellite systems can provide.In this paper,we try to perform reliable autonomous overtaking controls of vehicles,mainly based on the“relative”position information,including the distance,angle and velocity between vehicles,which can be achieved by on-board radars.To reduce the complexity of maneuvers,a fuzzy inference system is applied to analyze the driving behavior of the preceding vehicle based on the obtained consecutive relative position information.An output of“safe”or“dangerous”will be sent to the decision part based on reinforcement learning frameworks.Various overtaking maneuvers including“conservative”and“aggressive”can be obtained accordingly.Furthermore,we propose another overtaking strategy that vehicles can share their maneuver information during overtaking process via wireless links.Numeric results validate our analysis,and can provide meaningful performance benchmarks for practical system implementations.展开更多
Motion compensation based on the parameter estimation of a moving target has a strong influence on the inverse synthetic aperture radar(ISAR)imaging quality.For the target with built-in disturbance components or under...Motion compensation based on the parameter estimation of a moving target has a strong influence on the inverse synthetic aperture radar(ISAR)imaging quality.For the target with built-in disturbance components or under an extremely low signal-to-noise ratio(SNR),conventional parameter estimation methods based on cross-correlation processing of adjacent profiles,such as the cross-correlation method and the accumulated cross-correlation method,give sizable aligned errors and subsequently produce low-quality ISAR images.The fractional Fourier transform is capable of concentrating the signal power;however,a large computational complexity is induced by searching the matched order.In view of the problems above,a time-weighting symmetric accumulated cross-correlation method is proposed herein.This method maps the spectrum of the range profile into a single-peak envelope to reduce range alignment errors,and presents a symmetric accumulated manner to offset the accumulated error.The simulation results demonstrate that the proposed method yields much better estimation precision than other methods,and yields extremely low computational complexity.展开更多
文摘The relationship between physical activity time,openness and depression symptoms among adolescents is a cutting-edge research direction in the field,yet it remains unclear.This study is based on a sample of 7924 students from a nationally representative China Education Panel Survey database and examines the bidirectional relationships between physical activity time,openness and depression symptoms among Chinese adolescents.Descriptive analysis showed that during the 7th and 8th grades,the average physical activity time decreased to less than one hour per day,accompanied by a decreasing trend in openness and a slight worsening in depression symptoms.Correlation analysis showed a significant negative correlation between physical activity time and depression symptoms,a significant positive correlation between physical activity time and openness,and a significant negative correlation between depression symptoms and openness.The results from cross-lagged models indicated a bidirectional relationship between physical activity time and openness,with physical activity time significantly positively predicting openness in the following year and openness significantly positively predicting physical activity time in the following year.In addition,depression symptoms had a unidirectional negative predictive effect on openness.The conclusions provide empirical evidence for education administration and schools to promote the physical and mental health development of adolescents worldwide.
文摘Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim of evaluating the performance of an FSO communication system and extending the line-of-sight transmission distance,we propose an unmanned aerial vehicle(UAV)-assisted dual-hop FSO communication system equipped with amplifyand-forward protocol at the relay node.Specifically,we consider impairments of atmospheric absorption,pointing errors,atmospheric turbulence,and link interruptions due to angle-of-arrival fluctuations in the relay system.The Gamma-Gamma and Malaga distributions are used to model the influence of atmospheric turbulence on the source-to-UAV and UAVto-destination links,respectively.We derive closedform expressions of the probability density function(PDF)and cumulative distribution function(CDF)for the proposed communication system,in terms of the Meijer-G function.Based on the precise PDF and CDF,analytical expressions for the outage probability,average bit error rate,and ergodic capacity are proposed with the aid of the extended generalized bivariate Fox’s H function.Finally,we show that there is a match between the analytical results and numerical results,and we analyze the influence of the system and channel parameters on the performance.
基金supported in part by the National Natural Sciences Foundation of China (NSFC) under Grant 61525103the National Natural Sciences Foundation of China under Grant 61501140the Shenzhen Fundamental Research Project under Grant JCYJ20150930150304185
文摘Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA strategy, which might not be suited to the dynamic network environment. In this paper, we propose a multi-strategy DSA(MS-DSA) system, where the primary and the secondary system share spectrum resources with multiple DSA strategies simultaneously. To analyze the performance of the proposed MS-DSA system, we model it as a continuous-time Markov chain(CTMC) and derive the expressions to compute the corresponding performance metrics. Based on this, we define a utility function involving the concerns of effective throughput, interference quantity on primary users, and spectrum leasing cost. Two optimization schemes, named as spectrum allocation and false alarm probability selection, are proposed to maximize the utility function. Finally, numerical simulations are provided to validate our analysis and demonstrate that the performance can be significantly improved caused by virtues of the proposed MS-DSA system.
基金supported in part by the National Natural Sciences Foundation of China(NSFC)under Grant 61525103,the National Natural Sciences Foundation of China(NSFC)under Grant 61501140,the National Natural Sciences Foundation of China under Grant 61831008the Shenzhen Fundamental Research Project under Grant JCYJ20150930150304185+1 种基金the Guangdong Science and Technology Planning Project 2018B030322004in part by the Shenzhen Basic Research Program under Grant ZDSYS201707280903305
文摘Radio spectrum has become a rare resource due to the rapid development of wireless communication technique. Cognitive radio is one of important techniques to deal with this radio spectrum problem. But the resource allocation in cognitive radio also has its own issues, such as the flexibility of the allocation algorithm, the performance of resource allocation, and so on. In order to increase the flexibility of the allocation algorithm for cognitive radio, more and more researches are focusing on the evolutionary algorithms, such as genetic algorithm(GA), particle swarm optimization(PSO). Evolutionary algorithm can greatly improve the flexibility of the allocation algorithm for cognitive radio system in different communication scenarios, but the performances are relatively lower than the original mathematical methods. So in this paper, we proposed an adaptive resource allocation algorithm based on modified PSO for cognitive radio system to solve these problems. Modified particle swarm optimization(Modified PSO) has both genetic algorithm(GA) and particle swarm optimization(PSO)’s updating processes which makes this modified PSO overcame PSO’s own disadvantages and keep advantages. Simulation results showed our proposed algorithm has enough flexibility to meet cognitive radio systems’ requirements, and also has a better performance than original PSO.
文摘Mobile edge caching technology is gaining more and more attention because it can effectively improve the Quality of Experience (QoE) of users and reduce backhaul burden. This paper aims to improve the utility of mobile edge caching technology from the perspectie of caching resource management by examining a network composed of one operator, multiple users and Content Providers (CPs). The caching resource management model is constructed on the premise of fully considering the QoE of users and the servicing capability of the Base Station (BS). In order to create the best caching resource allocation scheme, the original problem is transformed into a multi-leader multi-follower Stackelberg game model through the analysis of the system model. The strategy combinations and the utility functions of players are analyzed. The existence and uniqueness of the Nash Equilibrium (NE) solution are also analyzed and proved. The optimal strategy combinations and the best responses are deduced in detail. Simulation results and analysis show that the proposed model and algorithm can achieve the optimal allocation of caching resource and improve the QoE of users.
基金the supports from the National Natural Science Foundation of China (61571156)Basic Research Project of Shenzhen (JCYJ20170413110004682 and JCYJ20150403161923521)。
文摘This work focuses on an unmanned aerial vehicle(UAV)-enabled mobile edge computing(MEC) system based on device-to-device(D2D) communication. In this system, the UAV exhibits caching,computing and relaying capabilities to periodically provide specific service to cellular users and D2D receiver nodes in the appointed time slot. Besides, the D2D transmitter can provide additional caching services to D2D receiver to reduce the pressure of the UAV. Note that communication between multi-type nodes is mutually restricted and different links share spectrum resources. To achieve an improved balance between different types of node, we aim to maximize the overall energy efficiency while satisfying the quality-of-service requirements of the cellular nodes.To address this problem, we propose an alternating iteration algorithm to jointly optimize the scheduling strategies of the user, transmitting power of the UAV and D2D-TX nodes, and UAV trajectory. The successive convex approximation, penalty function, and Dinkelbach method are employed to transform the original problem into a group of solvable subproblems and the convergence of the method is proved. Simulation results show that the proposed scheme performs better than other benchmark algorithms, particularly in terms of balancing the tradeoff between minimizing UAV energy consumption and maximizing throughput.
文摘Along with the swift growth of communication services,various networks have undergone multidimensional technical evolution,e.g.high transmission speed and large bandwidth for ground cellular network,high mobility for aviation network,and wide-area coverage for satellite network.As the industry demands for joint operation arise,an integrated space-air-ground collaboration network will be formed.
文摘Since the first space probe flew to the Moon in 1959,over 200 deep-space exploration missions have already been carried out on the eight planets,various asteroids and comets in the solar system.Amount of deepspace scientific experiments promoted people to understand about the origin and evolution of the universe.
基金National Natural Science Foundation of China(Grant Nos.61831008,61525103 and 61972113)the Guangdong Science and Tech⁃nology Planning Project(Grant No.2018B030322004)the Basic Research Project of Shenzhen Science and Technology Program(Grant No.JCYJ20190806112215116).
文摘Mobile Edge Computing(MEC)is a promising solution to tackle the upcoming computing tsunami in 5G/6G era by effectively utilizing the idle resource at the mobile edge.In this work,a multi⁃hop D2D⁃enabled MEC scenario was studied,where mobile devices at network edge connect and share resources with each other via multi⁃hop D2D.The research focus was on the micro⁃task scheduling problem in the multi⁃hop D2D⁃enabled MEC system,where each task was divided into multiple sequential micro⁃tasks,such as data downloading micro⁃task,data processing micro⁃task,and data uploading micro⁃task,according to their functionalities as well as resource requirements.A joint Task Failure Probability and Energy Consumption Minimization(TFP⁃ECM)problem was proposed,aiming at minimizing the task failure probability and the energy consumption jointly.To solve the problem,several linearization methods were proposed to relax the constraints and convert the original problem into an integer linear programming(ILP).Simulation results show that the proposed solution outperformed the existing solutions(with indivisible tasks or without resource sharing)in terms of both total cost and task failure probability.
基金Supported by the Science and Technology Project of Guizhou Province ((2022)YB176,[2020]1Y073,(2019)2773,[2019]3007)。
文摘In order to expand the sources of raw materials for edible fungus cultivation, reduce the use of wood, and realize the harmless treatment and efficient utilization of bamboo sawdust, bamboo sawdust was used to partially replace the broad-leaved wood sawdust in the conventional formula, and the growth of Ganoderma lucidum and Stropharia rugosoannulata mycelia in a large test tube in different matrix formulas was studied. The results show that the mycelia of the two edible fungi could grow normally in the matrices with bamboo sawdust;the growth of the mycelia in various formulas was different, and the performances of different strains of the same species were also different. Compared with the conventional formula, the suitable substitution amount of bamboo sawdust for the G. lucidum strains was 30%-45%, and that for S. rugosoannulata strains was 16%-32%.
基金Matching Technology Ripening in Efficiency Cultivation of Stropharia rugosoannulata of JunCao Industrialization and Its Popularization and Application(Science and Technology Planning Project[2020]1Y073)the Key Technology Research of Strain Breeding and Propagation of Bulk Edible Mushroom and Technological Industrialization Demonstration in Guizhou(Momentous Project of Guizhou Province Science and Technology[2019]3007).
文摘Stropharia rugosoannulata is a straw rotting edible fungus that has developed rapidly in recent years.In the process of cultivation,key technologies have a huge impact on its yield.The key techniques for the cultivation conditions and modes of S.rugosoannulata were summerized to promote the realization of stable and high yield of S.rugosoannulata.
基金supported in part by the National Natural Sciences Foundation of China(Nos.61771158,61871147,61831008,91638204 and 61525103)the Shenzhen Basic Research Program(Nos.JCYJ20170811154309920,JCYJ20170811160142808,and ZDSYS201707280903305)Guangdong Science and Technology Planning Project(No.2018B030322004).
文摘The increasing demands in terms of high data rate and quality of services over the hybrid satellite-terrestrial relay networks(HSTRN)have pushed for the development of millimeter-wave(mmWave)band high-throughput satellites(HTS)with multibeams.The next generation of mmWave multibeam HTS communication systems(HTSCS)is viewed as the backbone network to enhance the throughput of the HSTRN.The article first investigates the basic backbone topology architecture of HTSCS,and an M-state Markov channel for the Ka/Q/V band mmWave systems is reviewed.Then,we propose a long-term optimal power allocation scheme over two in-dependent and identical spot beams based on the partially observable Markov decision process(POMDP),which can partly mitigate the negative effects of severe weather conditions.The key conditions for selecting the optimal power allocation action in the multibeam HTSCS are given.Simulation results show that our POMDP-based power allocation scheme can enhance the long-term throughput of the HTSCS.
基金This work was supported by the National Natural Science Foundation of China(No.91638204).
文摘Unlimited and seamless coverage as well as ultra-reliable and low-latency communications are vital for connected vehicles,in particular for new use cases like autonomous driving and vehicle platooning.In this paper,we propose a novel Space-Air-Ground integrated vehicular network(SAGiven)architecture to gracefully integrate the multi-dimensional and multi-scale context-information and network resources from satellites,High-Altitude Platform stations(HAPs),low-altitude Unmanned Aerial Vehicles(UAVs),and terrestrial cellular communication systems.One of the key features of the SAGiven is the reconfigurability of heterogeneous network functions as well as network resources.We first give a comprehensive review of the key challenges of this new architecture and then provide some up-to-date solutions on those challenges.Specifically,the solutions will cover the following topics:(1)space-air-ground integrated network reconfiguration under dynamic space resources constraints;(2)multi-dimensional sensing and efficient integration of multi-dimensional context information;(3)real-time,reliable,and secure communications among vehicles and between vehicles and the SAGiven platform;and(4)a holistic integration and demonstration of the SAGiven.Finally,it is concluded that the SAGiven can play a key role in future autonomous driving and Internet-of-Vehicles applications.
基金supported by the National Natural Science Foundation of China(Nos.91638204 and 61771159)Guangdong Natural Science Foundation(No.2017A030313392)Shenzhen Fundamental Research Project(No.JCYJ20170811153639780).
文摘Appropriate traffic coordination at road intersections plays a crucial part in modern intelligent transportation systems.In this paper,we first try to extend the traditional single collision-set coordination strategy to multiple-collision-set strategies,by which the traffic throughput can be significantly improved.Unlike the existing centralized coordination methods,two low complexity coordination methods are proposed based on the multi-agents Q-learning frameworks.Numerical results show that,the proposed high throughput strategies are able to provide safe and efficient traffic coordination.Meanwhile,since only local information is required,the coordination complexity can be reduced,which is attractive in highly dynamic real time scenarios.
基金supported by the Natural Science Foundation of China(under Grant No.91638204 and 61771159)Guangdong Natural Science Foundation under Grant No.2017A030313392Shenzhen Fundamental Research Project under Grant No.JCYJ20170811153639780。
文摘Reliable and efficient overtaking maneuvers are important and challenging for autonomous vehicles.Higher precision position information is thus required,rather than that traditional global navigation satellite systems can provide.In this paper,we try to perform reliable autonomous overtaking controls of vehicles,mainly based on the“relative”position information,including the distance,angle and velocity between vehicles,which can be achieved by on-board radars.To reduce the complexity of maneuvers,a fuzzy inference system is applied to analyze the driving behavior of the preceding vehicle based on the obtained consecutive relative position information.An output of“safe”or“dangerous”will be sent to the decision part based on reinforcement learning frameworks.Various overtaking maneuvers including“conservative”and“aggressive”can be obtained accordingly.Furthermore,we propose another overtaking strategy that vehicles can share their maneuver information during overtaking process via wireless links.Numeric results validate our analysis,and can provide meaningful performance benchmarks for practical system implementations.
基金This work is supported in part by the National Science Foundation for the Distinguished Young Scholars of China(No.61525103)the Shenzhen Fundamental Research Project(No.JCYJ20150930150304185).
文摘Motion compensation based on the parameter estimation of a moving target has a strong influence on the inverse synthetic aperture radar(ISAR)imaging quality.For the target with built-in disturbance components or under an extremely low signal-to-noise ratio(SNR),conventional parameter estimation methods based on cross-correlation processing of adjacent profiles,such as the cross-correlation method and the accumulated cross-correlation method,give sizable aligned errors and subsequently produce low-quality ISAR images.The fractional Fourier transform is capable of concentrating the signal power;however,a large computational complexity is induced by searching the matched order.In view of the problems above,a time-weighting symmetric accumulated cross-correlation method is proposed herein.This method maps the spectrum of the range profile into a single-peak envelope to reduce range alignment errors,and presents a symmetric accumulated manner to offset the accumulated error.The simulation results demonstrate that the proposed method yields much better estimation precision than other methods,and yields extremely low computational complexity.
