This paper proposes a theoretical framework based on new household economic theories. A dataset from the 2006 China Health and Nutrition Survey (CHNS) is used. Given heterogeneity in major family members' jobs, the...This paper proposes a theoretical framework based on new household economic theories. A dataset from the 2006 China Health and Nutrition Survey (CHNS) is used. Given heterogeneity in major family members' jobs, the effect of non-labor income on household time allocation is discussed under two scenarios: jobs with flexible work hours and jobs with fixed work hours in the market. Based on the nature of the employer the major family member works for, employers can be categorized into four categories: government-owned, family contract, privately-owned, and foreign-funded. Each of the four categories is used for dissecting the data into different sets for analysis by category. The results imply that job heterogeneity is significantly correlated to household time allocation. An increase in non-labor income results in a decrease in the time allocated to housework for all households. However, leisure time is allocated differently among different households due to job heterogeneity. An increase in non-labor income leads to less leisure time for households working for government-owned or foreign-funded enterprises, and more leisure time for households working for family contract or privately-owned enterprises.展开更多
Rivers are important habitats for wintering waterbirds.However,they are easily influenced by natural and human activities.An important approach for waterbirds to adapt to habitats is adjusting the activity time and en...Rivers are important habitats for wintering waterbirds.However,they are easily influenced by natural and human activities.An important approach for waterbirds to adapt to habitats is adjusting the activity time and energy expenditure allocation of diurnal behavior.The compensatory foraging hypothesis predicts that increased energy expenditure leads to longer foraging time,which in turn increases food intake and helps maintain a constant energy balance.However,it is unclear whether human-disturbed habitats result in increased energy expenditure related to safety or foraging.In this study,the scan sample method was used to observe the diurnal behavior of the wintering Spot-billed Duck(Anas poecilorhyncha) in two rivers in the Xin’an River Basin from October 2021 to March 2022.The allocation of time and energy expenditure for activity in both normal and disturbed environments was calculated.The results showed that foraging accounted for the highest percentage of time and energy expenditure.Additionally,foraging decreased in the disturbed environment than that in the normal environment.Resting behavior showed the opposite trend,while other behaviors were similar in both environments.The total diurnal energy expenditure of ducks in the disturbed environment was greater than that in the normal environment,with decreased foraging and resting time percentage and increased behaviors related to immediate safety(swimming and alert) and comfort.These results oppose the compensatory foraging hypothesis in favor of increased security.The optimal diurnal energy expenditure model included river width and water depth,which had a positive relationship;an increase in either of these two factors resulted in an increase in energy expenditure.This study provides a better understanding of energy allocation strategies underlying the superficial time allocation of wintering waterbirds according to environmental conditions.Exploring these changes can help understand the maximum fitness of wintering waterbirds in response to nature and human influences.展开更多
Time allocations of the group-living Tibetan eared pheasants Crossoptilon harmani with and without supplementary food were investigated by full-day sampling from winter through spring in an alpine scrub zone, south Ti...Time allocations of the group-living Tibetan eared pheasants Crossoptilon harmani with and without supplementary food were investigated by full-day sampling from winter through spring in an alpine scrub zone, south Tibet. At a flock scale, both the different food-supply flocks displayed similar daily patterns of activity, foraging in the morning and evening, and resting around midday. In terms of individual activity, either foraging or resting was highly synchronous with the flock's. Non-provisioned birds spent more time feeding and less resting in midwinter than in late autumn. In early spring as climates became warmer and day longer, however, non-provisioned birds did not decrease their feeding efforts significantly but the provisioned birds did. Across the non-breeding seasons, the provisioned birds (relying on nutrition-rich artificial food) devoted less time to feeding and more to resting than did the non-provisioned ones (relying on nutrition-poor plant roots). Multivariate analysis showed increased food supply and ambient temperature resulted in a reduced foraging effort. However, the fact that the non-provisioned birds can save daily time for resting even in the cold short-day length mid-winter indicated that they faced no energetic constraint. Thus, protecting shelter vegetation rather than providing extra food is suggested to be important for long-term survival of the endangered galliform birds [ Current Zoology 55 (3) : 193 - 199, 2009] .展开更多
Nodes in the communication network mainly depend on the Media Access Control(MAC)layer protocol design.To ensure the MAC protocol achieves high throughput,low latency,and high service quality,this paper designed a“ce...Nodes in the communication network mainly depend on the Media Access Control(MAC)layer protocol design.To ensure the MAC protocol achieves high throughput,low latency,and high service quality,this paper designed a“centralized-distribution”system MAC protocol combined with a slot allocation algorithm.This allows it to quickly adapt to the topology changes in the network and the overall network frame structure.For the centralized time slot allocation,since the system’s frame structure changes across the entire network,the root node must gather information from other nodes.This ensures that the root node can collect the latest topology information when the network topology changes and subsequently adjust the frame structure of the whole network for the distributed time slot allocation.The simulation results show that the adaptive time-division multiple access mechanism can quickly adapt to changes in topology and the network’s frame structure.It enables adaptive changes in node transmission times,ensures the rapid transmission and circulation of large-capacity data between nodes,and improves transmission efficiency.展开更多
In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant ...In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant effects upon the traffic delay per- formance. This article proposes models to analyze the relationships among frame length, bandwidth assignment (assigned time slot count), time slot location in frame, and traffic delay performance for traffics of constant bit rate (CBR) and variable bit rate (...展开更多
As a promising solution, virtualization is vigorously developed to eliminate the ossification of traditional Internet infrastructure and enhance the flexibility in sharing the substrate network (SN) resources includin...As a promising solution, virtualization is vigorously developed to eliminate the ossification of traditional Internet infrastructure and enhance the flexibility in sharing the substrate network (SN) resources including computing, storage, bandwidth, etc. With network virtualization, cloud service providers can utilize the shared substrate resources to provision virtual networks (VNs) and facilitate a wide and diverse range of applications. As more and more internet applications migrate to the cloud, the resource efficiency and the survivability of VNs, such as single link failure or large-scale disaster survivability, have become crucial issues. Elastic optical networks have emerged in recent years as a strategy for dealing with the divergence of network application bandwidth needs. The network capacity has been constrained due to the usage of only two multiplexing dimensions. As transmission rates rise, so does the demand for network failure protection. Due to their end-to-end solutions, those safe-guarding paths are of particular importance among the protection methods. Due to their end-to-end solutions, those safeguarding paths are of particular importance among the protection methods. This paper presents approaches that provide a failure-independent route-protecting p-cycle for path protection in space-division multiplexed elastic optical networks. This letter looks at two SDM network challenges and presents a heuristic technique (k-shortest path) for each. In the first approach, we study a virtual network embedding (SVNE) problem and propose an algorithm for EONs, which can combat against single-link failures. We evaluate the proposed POPETA algorithm and compare its performance with some counterpart algorithms. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance in terms of spectrum utilization and blocking ratio, even if with a higher backup redundancy ratio.展开更多
This paper presents a symmetric cooperation strategy for cooperative relay networks with multiple users. The multi-user symmetric cooperation model and the relay selection algorithm are proposed. Then, the time slot a...This paper presents a symmetric cooperation strategy for cooperative relay networks with multiple users. The multi-user symmetric cooperation model and the relay selection algorithm are proposed. Then, the time slot allocation problem is cast into a bargaining problem, and the optimal time slot allocation solution is obtained by Nash bargaining solution (NBS). Moreover, we also consider the implementations of the cooperation strategy, i.e., the grouping and admission control algorithm. Simulation results show that users can obtain larger rates under the symmetric cooperation strategy than the non-cooperative case.展开更多
Information centric networking(ICN) is a new network architecture that is centred on accessing content. It aims to solve some of the problems associated with IP networks, increasing content distribution capability and...Information centric networking(ICN) is a new network architecture that is centred on accessing content. It aims to solve some of the problems associated with IP networks, increasing content distribution capability and improving users' experience. To analyse the requests' patterns and fully utilize the universal cached contents, a novel intelligent resources management system is proposed, which enables effi cient cache resource allocation in real time, based on changing user demand patterns. The system is composed of two parts. The fi rst part is a fi ne-grain traffi c estimation algorithm called Temporal Poisson traffi c prediction(TP2) that aims at analysing the traffi c pattern(or aggregated user requests' demands) for different contents. The second part is a collaborative cache placement algorithm that is based on traffic estimated by TP2. The experimental results show that TP2 has better performance than other comparable traffi c prediction algorithms and the proposed intelligent system can increase the utilization of cache resources and improve the network capacity.展开更多
Referring to a set of real time tasks with arriving time,executing time and deadline,this paperdiscusses the problem of polynomial time initial-allocating approximation algorithms in a distributedsystem and five new r...Referring to a set of real time tasks with arriving time,executing time and deadline,this paperdiscusses the problem of polynomial time initial-allocating approximation algorithms in a distributedsystem and five new results are gained which provide a theory for the designing of initial-allocating algorithmsof real time tasks.展开更多
With the advantages of low cost and high mobility,unmanned aerial vehicles(UAVs)have played an important role in wireless communication.We investigate a UAV-enabled mobile relaying system,where a UAV is used as a mobi...With the advantages of low cost and high mobility,unmanned aerial vehicles(UAVs)have played an important role in wireless communication.We investigate a UAV-enabled mobile relaying system,where a UAV is used as a mobile relay to assist in the communication from a ground source to a ground destination since their direct link is blocked.Unlike the conventional mobile relay in which the UAV adopts straight line or circular trajectory,we consider a more general elliptical trajectory and use realistic channel models.By assuming that the UAV employs time-division duplexing(TDD)based decode-and-forward(DF)relaying,we jointly optimize the time allocations and the UAV trajectory to formulate the maximization of spectrum efficiency(SE).The simulation results show that the trajectory we designed achieves a higher SE than the optimal circular trajectory and static relaying.展开更多
The availalability. use, development, and management of water resources are receivingincreasing attentioll worldwide. As demands for water continues to grow and the resources continue todwindle or at best remain cons...The availalability. use, development, and management of water resources are receivingincreasing attentioll worldwide. As demands for water continues to grow and the resources continue todwindle or at best remain constant at some level, it has become increasingly necessary to develop moreand more methods for the managaement of this scarce resource especially in arid and semiarid regions.The necessity of integrated planning and management of the basin arises because of insufficient anderratic nature of the rainfall. The purpose of this paper is to determine the optimal operation policy ofthe water resources for the river basins to meet the multi-objective demands of water requirements. Anoptimization approach has been developed to aid decision making in the real time allocation of waterwithin t he context of a large-scale, multi-objective, complex river system. The optimization approach isbased on the Progressive Optimality Algorithm, Golden Search techniqlle, and the ε-constraint method.As a case study, the present methodology is applied to the Yellow River Reservoir system in China andpresented in a companion paper in this issue.展开更多
The rapid boosting in mobile traffic and the scarcity of available radio spectrum have hindered the improvement of capacity in cellular networks.It is necessary to discover an appropriate coexistence between cellular ...The rapid boosting in mobile traffic and the scarcity of available radio spectrum have hindered the improvement of capacity in cellular networks.It is necessary to discover an appropriate coexistence between cellular and other radio access technologies(mainly Wi-Fi)to offload the high traffic on to unlicensed bands.Dealing with joint time and power allocation to devices,a non-convex problem is modeled to maximize the throughput as well as guarantee the desired user satisfaction.A two-step traffic balancing scheme is proposed to derive the solution.We also focus on the inner competition among cellular users instead of traditional competition between cellular and Wi-Fi in the unlicensed bands.Finally,simulation results show the effectiveness of the proposed two-step traffic balancing scheme.展开更多
The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks (CRNs). Existing research has focused on the dual-hop network, which cannot be extend...The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks (CRNs). Existing research has focused on the dual-hop network, which cannot be extended to a triple-hop network due to its shortcomings, including the limited transmission range and one-way communication. In this paper, a novel, triple-hop relay scheme is proposed to implement time-division duplex (TDD) transmission among secondary users (SUs) in a three-phase transmission. Moreover, a superposition coding (SC) method is adopted for handling two-receiver cases in triple-hop networks with a cognitive relay. We studied a joint optimization of time and power allocation in all three phases, which is formulated as a nonlinear and concave problem. Both analytical and numerical results show that the proposed scheme is able to improve the throughput of SUs, and enlarge the transmission range of primary users (PUs) without increasing the number of hops.展开更多
基金Acknowledgements We would like to thank National Natural Science Foundation of China (No. 71203129), Social Sciences Fund Project of China' s Ministry of Education in 2012 ( No. 12JYC790062) and Shanghai Shuguang Plan (No. 13 SG36) for supporting our research.
文摘This paper proposes a theoretical framework based on new household economic theories. A dataset from the 2006 China Health and Nutrition Survey (CHNS) is used. Given heterogeneity in major family members' jobs, the effect of non-labor income on household time allocation is discussed under two scenarios: jobs with flexible work hours and jobs with fixed work hours in the market. Based on the nature of the employer the major family member works for, employers can be categorized into four categories: government-owned, family contract, privately-owned, and foreign-funded. Each of the four categories is used for dissecting the data into different sets for analysis by category. The results imply that job heterogeneity is significantly correlated to household time allocation. An increase in non-labor income results in a decrease in the time allocated to housework for all households. However, leisure time is allocated differently among different households due to job heterogeneity. An increase in non-labor income leads to less leisure time for households working for government-owned or foreign-funded enterprises, and more leisure time for households working for family contract or privately-owned enterprises.
基金supported by the National Natural Science Foundation of China (Grant No. 32100400)Huangshan University Startup Project of Scientific Research (2020xkjq013)Environment Conservation Research Centre of Xin’an River Basin (kypt202002)。
文摘Rivers are important habitats for wintering waterbirds.However,they are easily influenced by natural and human activities.An important approach for waterbirds to adapt to habitats is adjusting the activity time and energy expenditure allocation of diurnal behavior.The compensatory foraging hypothesis predicts that increased energy expenditure leads to longer foraging time,which in turn increases food intake and helps maintain a constant energy balance.However,it is unclear whether human-disturbed habitats result in increased energy expenditure related to safety or foraging.In this study,the scan sample method was used to observe the diurnal behavior of the wintering Spot-billed Duck(Anas poecilorhyncha) in two rivers in the Xin’an River Basin from October 2021 to March 2022.The allocation of time and energy expenditure for activity in both normal and disturbed environments was calculated.The results showed that foraging accounted for the highest percentage of time and energy expenditure.Additionally,foraging decreased in the disturbed environment than that in the normal environment.Resting behavior showed the opposite trend,while other behaviors were similar in both environments.The total diurnal energy expenditure of ducks in the disturbed environment was greater than that in the normal environment,with decreased foraging and resting time percentage and increased behaviors related to immediate safety(swimming and alert) and comfort.These results oppose the compensatory foraging hypothesis in favor of increased security.The optimal diurnal energy expenditure model included river width and water depth,which had a positive relationship;an increase in either of these two factors resulted in an increase in energy expenditure.This study provides a better understanding of energy allocation strategies underlying the superficial time allocation of wintering waterbirds according to environmental conditions.Exploring these changes can help understand the maximum fitness of wintering waterbirds in response to nature and human influences.
基金support was provided by National Sciences Foundation of China(grants 30330050 and 30425036)
文摘Time allocations of the group-living Tibetan eared pheasants Crossoptilon harmani with and without supplementary food were investigated by full-day sampling from winter through spring in an alpine scrub zone, south Tibet. At a flock scale, both the different food-supply flocks displayed similar daily patterns of activity, foraging in the morning and evening, and resting around midday. In terms of individual activity, either foraging or resting was highly synchronous with the flock's. Non-provisioned birds spent more time feeding and less resting in midwinter than in late autumn. In early spring as climates became warmer and day longer, however, non-provisioned birds did not decrease their feeding efforts significantly but the provisioned birds did. Across the non-breeding seasons, the provisioned birds (relying on nutrition-rich artificial food) devoted less time to feeding and more to resting than did the non-provisioned ones (relying on nutrition-poor plant roots). Multivariate analysis showed increased food supply and ambient temperature resulted in a reduced foraging effort. However, the fact that the non-provisioned birds can save daily time for resting even in the cold short-day length mid-winter indicated that they faced no energetic constraint. Thus, protecting shelter vegetation rather than providing extra food is suggested to be important for long-term survival of the endangered galliform birds [ Current Zoology 55 (3) : 193 - 199, 2009] .
文摘Nodes in the communication network mainly depend on the Media Access Control(MAC)layer protocol design.To ensure the MAC protocol achieves high throughput,low latency,and high service quality,this paper designed a“centralized-distribution”system MAC protocol combined with a slot allocation algorithm.This allows it to quickly adapt to the topology changes in the network and the overall network frame structure.For the centralized time slot allocation,since the system’s frame structure changes across the entire network,the root node must gather information from other nodes.This ensures that the root node can collect the latest topology information when the network topology changes and subsequently adjust the frame structure of the whole network for the distributed time slot allocation.The simulation results show that the adaptive time-division multiple access mechanism can quickly adapt to changes in topology and the network’s frame structure.It enables adaptive changes in node transmission times,ensures the rapid transmission and circulation of large-capacity data between nodes,and improves transmission efficiency.
基金National Natural Science Foundation of China (60532030)National Natural Science Foundation for Distinguished Young Scholars (60625102)
文摘In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant effects upon the traffic delay per- formance. This article proposes models to analyze the relationships among frame length, bandwidth assignment (assigned time slot count), time slot location in frame, and traffic delay performance for traffics of constant bit rate (CBR) and variable bit rate (...
文摘As a promising solution, virtualization is vigorously developed to eliminate the ossification of traditional Internet infrastructure and enhance the flexibility in sharing the substrate network (SN) resources including computing, storage, bandwidth, etc. With network virtualization, cloud service providers can utilize the shared substrate resources to provision virtual networks (VNs) and facilitate a wide and diverse range of applications. As more and more internet applications migrate to the cloud, the resource efficiency and the survivability of VNs, such as single link failure or large-scale disaster survivability, have become crucial issues. Elastic optical networks have emerged in recent years as a strategy for dealing with the divergence of network application bandwidth needs. The network capacity has been constrained due to the usage of only two multiplexing dimensions. As transmission rates rise, so does the demand for network failure protection. Due to their end-to-end solutions, those safe-guarding paths are of particular importance among the protection methods. Due to their end-to-end solutions, those safeguarding paths are of particular importance among the protection methods. This paper presents approaches that provide a failure-independent route-protecting p-cycle for path protection in space-division multiplexed elastic optical networks. This letter looks at two SDM network challenges and presents a heuristic technique (k-shortest path) for each. In the first approach, we study a virtual network embedding (SVNE) problem and propose an algorithm for EONs, which can combat against single-link failures. We evaluate the proposed POPETA algorithm and compare its performance with some counterpart algorithms. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance in terms of spectrum utilization and blocking ratio, even if with a higher backup redundancy ratio.
基金supported by National Basic Research Program of China (973 Program) (No. 2010CB731800)Key Project of National Natural Science Foundation of China (No. 60934003)Scientific and Technological Supporting Project of Hebei Province(No. 072435155D)
文摘This paper presents a symmetric cooperation strategy for cooperative relay networks with multiple users. The multi-user symmetric cooperation model and the relay selection algorithm are proposed. Then, the time slot allocation problem is cast into a bargaining problem, and the optimal time slot allocation solution is obtained by Nash bargaining solution (NBS). Moreover, we also consider the implementations of the cooperation strategy, i.e., the grouping and admission control algorithm. Simulation results show that users can obtain larger rates under the symmetric cooperation strategy than the non-cooperative case.
基金supported by the National High Technology Research and Development Program(863)of China(No.2015AA016101)the National Natural Science Fund(No.61300184)Beijing Nova Program(No.Z151100000315078)
文摘Information centric networking(ICN) is a new network architecture that is centred on accessing content. It aims to solve some of the problems associated with IP networks, increasing content distribution capability and improving users' experience. To analyse the requests' patterns and fully utilize the universal cached contents, a novel intelligent resources management system is proposed, which enables effi cient cache resource allocation in real time, based on changing user demand patterns. The system is composed of two parts. The fi rst part is a fi ne-grain traffi c estimation algorithm called Temporal Poisson traffi c prediction(TP2) that aims at analysing the traffi c pattern(or aggregated user requests' demands) for different contents. The second part is a collaborative cache placement algorithm that is based on traffic estimated by TP2. The experimental results show that TP2 has better performance than other comparable traffi c prediction algorithms and the proposed intelligent system can increase the utilization of cache resources and improve the network capacity.
文摘Referring to a set of real time tasks with arriving time,executing time and deadline,this paperdiscusses the problem of polynomial time initial-allocating approximation algorithms in a distributedsystem and five new results are gained which provide a theory for the designing of initial-allocating algorithmsof real time tasks.
基金supported by the National Natural Science Foundation of China (61671073)Youth Science Foundation of Hubei University (201811193000006)
文摘With the advantages of low cost and high mobility,unmanned aerial vehicles(UAVs)have played an important role in wireless communication.We investigate a UAV-enabled mobile relaying system,where a UAV is used as a mobile relay to assist in the communication from a ground source to a ground destination since their direct link is blocked.Unlike the conventional mobile relay in which the UAV adopts straight line or circular trajectory,we consider a more general elliptical trajectory and use realistic channel models.By assuming that the UAV employs time-division duplexing(TDD)based decode-and-forward(DF)relaying,we jointly optimize the time allocations and the UAV trajectory to formulate the maximization of spectrum efficiency(SE).The simulation results show that the trajectory we designed achieves a higher SE than the optimal circular trajectory and static relaying.
文摘The availalability. use, development, and management of water resources are receivingincreasing attentioll worldwide. As demands for water continues to grow and the resources continue todwindle or at best remain constant at some level, it has become increasingly necessary to develop moreand more methods for the managaement of this scarce resource especially in arid and semiarid regions.The necessity of integrated planning and management of the basin arises because of insufficient anderratic nature of the rainfall. The purpose of this paper is to determine the optimal operation policy ofthe water resources for the river basins to meet the multi-objective demands of water requirements. Anoptimization approach has been developed to aid decision making in the real time allocation of waterwithin t he context of a large-scale, multi-objective, complex river system. The optimization approach isbased on the Progressive Optimality Algorithm, Golden Search techniqlle, and the ε-constraint method.As a case study, the present methodology is applied to the Yellow River Reservoir system in China andpresented in a companion paper in this issue.
基金supported by The National Natural Science Foundation of China(No.61471058)Beijing Nova Program(No.xx2012037).
文摘The rapid boosting in mobile traffic and the scarcity of available radio spectrum have hindered the improvement of capacity in cellular networks.It is necessary to discover an appropriate coexistence between cellular and other radio access technologies(mainly Wi-Fi)to offload the high traffic on to unlicensed bands.Dealing with joint time and power allocation to devices,a non-convex problem is modeled to maximize the throughput as well as guarantee the desired user satisfaction.A two-step traffic balancing scheme is proposed to derive the solution.We also focus on the inner competition among cellular users instead of traditional competition between cellular and Wi-Fi in the unlicensed bands.Finally,simulation results show the effectiveness of the proposed two-step traffic balancing scheme.
基金Project supported by the Zhejiang Provincial National Natural Science Foundation (No. LQ14F020005), the National Natural Science Foundation of China (Nos. 61379123 and 61402414), and the Research Program of the Educational Commission of Zhej iang Province, China (No. Y201431815)
文摘The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks (CRNs). Existing research has focused on the dual-hop network, which cannot be extended to a triple-hop network due to its shortcomings, including the limited transmission range and one-way communication. In this paper, a novel, triple-hop relay scheme is proposed to implement time-division duplex (TDD) transmission among secondary users (SUs) in a three-phase transmission. Moreover, a superposition coding (SC) method is adopted for handling two-receiver cases in triple-hop networks with a cognitive relay. We studied a joint optimization of time and power allocation in all three phases, which is formulated as a nonlinear and concave problem. Both analytical and numerical results show that the proposed scheme is able to improve the throughput of SUs, and enlarge the transmission range of primary users (PUs) without increasing the number of hops.