With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)sat...With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)satellite networks.While due to the scarcity of bandwidth resources and dynamic topology of LEO satellites,the static SFC placement schemes may cause performance degradation,resource waste and even service failure.In this paper,we consider migration and establish an online migration model,especially considering the dynamic topology.Given the scarcity of bandwidth resources,the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as possible.Due to its NP-hardness,we propose a heuristic minimized dynamic SFC migration(MDSM)algorithm that only triggers the migration procedure when new SFCs are rejected.Simulation results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.展开更多
An emerging railway technology called smart railway promises to deliver higher transportation efficiency,enhanced comfort in services,and greater eco-friendliness.The smart railway is expected to integrate fifth-gener...An emerging railway technology called smart railway promises to deliver higher transportation efficiency,enhanced comfort in services,and greater eco-friendliness.The smart railway is expected to integrate fifth-generation mobile communication(5G),Artificial Intelligence(AI),and other technologies,which poses new problems in the construction,operation and maintenance of railway wireless networks.Wireless Digital Twins(DTs),which have recently emerged as a new paradigm for the design of wireless networks,can address these problems and enable the whole lifecycle management of railway wireless networks.However,there are still many scientific issues and challenges for railway-oriented wireless DT.Relevant key technologies to solve these problems are introduced and described,including characterization of materials'physical-EM properties,autonomous reconstruction of Three-dimensional(3D)environment model,AI-empowered environmental cognition,Ray-Tracing(RT),model-based and AIbased RT acceleration,and generation of multi-spectra sensing data.Moreover,this paper presents our research results for each key technology and describes the wireless network planning and optimization system based on highperformance RT developed by our laboratory.This paper outlines the framework for realizing the wireless DT of smart railways,providing the direction for future research.展开更多
As 5th Generation(5G)and Beyond 5G(B5G)networks become increasingly prevalent,ensuring not only networksecurity but also the security and reliability of the applications,the so-called network applications,becomesof pa...As 5th Generation(5G)and Beyond 5G(B5G)networks become increasingly prevalent,ensuring not only networksecurity but also the security and reliability of the applications,the so-called network applications,becomesof paramount importance.This paper introduces a novel integrated model architecture,combining a networkapplication validation framework with an AI-driven reactive system to enhance security in real-time.The proposedmodel leverages machine learning(ML)and artificial intelligence(AI)to dynamically monitor and respond tosecurity threats,effectively mitigating potential risks before they impact the network infrastructure.This dualapproach not only validates the functionality and performance of network applications before their real deploymentbut also enhances the network’s ability to adapt and respond to threats as they arise.The implementation ofthis model,in the shape of an architecture deployed in two distinct sites,demonstrates its practical viability andeffectiveness.Integrating application validation with proactive threat detection and response,the proposed modeladdresses critical security challenges unique to 5G infrastructures.This paper details the model,architecture’sdesign,implementation,and evaluation of this solution,illustrating its potential to improve network securitymanagement in 5G environments significantly.Our findings highlight the architecture’s capability to ensure boththe operational integrity of network applications and the security of the underlying infrastructure,presenting asignificant advancement in network security.展开更多
The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential so...The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential solution for this purpose,although continuous oscillation at super large incident angle remains challenging.In this work,we employ the CCA resonator to generate continuous oscillation within±20°angular misalignment of cavity mirror in experiment.On the basis of retroreflection theory,the retroreflectivity of a CCA is analyzed by using optical simulation software.Notably,the experiment verifies the advantage of using a CCA over a plane mirror in laser resonator,thereby providing a promising approach for ECDLs.The threshold characteristic curves measured at different incident angles in the experiment verify that the CCA possesses an obvious anti-angle misalignment performance.This research introduces an alternative solution of using CCA resonator instead of parallel plane cavity,thereby realizing an adjustment-free ECDL with enhanced mechanical stability.展开更多
The trends and characteristics of global CH_(4)emissions were analyzed using greenhouse gas data reported by both Annex I and non-Annex I countries under the United Nations Framework Convention on Climate Change(UNFCC...The trends and characteristics of global CH_(4)emissions were analyzed using greenhouse gas data reported by both Annex I and non-Annex I countries under the United Nations Framework Convention on Climate Change(UNFCCC)from 1990 to 2021.The results show the following:(1)In 2021,the cumulative CH_(4)emissions from the 42 nations listed in Annex I of the UNFCCC amounted to 1871521.79 kt CO_(2)eq.The top 10 countries account for 82.0%of the total CH_(4)emissions.(2)Most Annex I countries showed a gradual decline in CH_(4)emissions over the period.In contrast,emissions from non-Annex I countries have increased year by year.Notably,CH_(4)emissions in the United States,the European Union,the Russian Federation,and Ukraine decreased by 14.0%,37.4%,24.0%,and 60.9%,respectively.(3)In 2020,the CH_(4)emissions of the agriculture,energy,waste treatment and LULUCF(land use,land-use change and forestry)sectors in Annex I countries were 72240.43,63863.51,41573.08,and 889019 million tons of CO_(2)eq,accounting for 38.6%,34.1%,22.2%,and 4.8%,respectively.Among non-Annex I countries,the main CH_(4)sources vary by country.In China and Mexico,energy and agriculture were the largest contributors,accounting for 44.8%and 40.2%in China,and 34.4%and 43.3%in Mexico,respectively.In India,Brazil,Nigeria,Argentina,and Vietnam,agriculture dominated,contributing 73.8%,75.8%,59.7%,60.3%,and 58.5%of total emissions,respectively.Indonesia was an exception,with waste treatment being the primary source,accounting for 64.8%of its total CH_(4)emissions.展开更多
Internet of things and network densification bring significant challenges to uplink management.Only depending on optimization algorithm enhancements is not enough for uplink transmission.To control intercell interfere...Internet of things and network densification bring significant challenges to uplink management.Only depending on optimization algorithm enhancements is not enough for uplink transmission.To control intercell interference,Fractional Uplink Power Control(FUPC)should be optimized from network-wide perspective,which has to find a better traffic distribution model.Conventionally,traffic distribution is geographic-based,and ineffective due to tricky locating efforts.This paper proposes a novel uplink power management framework for Self-Organizing Networks(SON),which firstly builds up pathloss-based traffic distribution model and then makes the decision of FUPC based on the model.PathLoss-based Traffic Distribution(PLTD)aggregates traffic based on the propagation condition of traffic that is defined as the pathloss between the position generating the traffic and surrounding cells.Simulations show that the improvement in optimization efficiency of FUPC with PLTD can be up to 40%compared to conventional GeoGraphic-based Traffic Distribution(GGTD).展开更多
Underwater acoustic sensor networks(UWASNs)aim to find varied offshore ocean monitoring and exploration applications.In most of these applications,the network is composed of several sensor nodes deployed at different ...Underwater acoustic sensor networks(UWASNs)aim to find varied offshore ocean monitoring and exploration applications.In most of these applications,the network is composed of several sensor nodes deployed at different depths in the water.Sensor nodes located at depth on the seafloor cannot invariably communicate with nodes close to the surface level;these nodes need multihop communication facilitated by a suitable routing scheme.In this research work,a Cluster-based Cooperative Energy Efficient Routing(CEER)mechanism for UWSNs is proposed to overcome the shortcomings of the Co-UWSN and LEACH mechanisms.The optimal role of clustering and cooperation provides load balancing and improves the network profoundly.The simulation results using MATLAB show better performance of CEER routing protocol in terms of various parameters as compared to Co-UWSN routing protocol,i.e.,the average end-to-end delay of CEER was 17.39,Co-UWSN was 55.819 and LEACH was 70.08.In addition,the average total energy consumption of CEER was 9.273,Co-UWSN was 12.198,and LEACH was 45.33.The packet delivery ratio of CEER was 53.955,CO-UWSN was 42.047,and LEACH was 30.31.The stability period CEER was 130.9,CO-UWSN was 129.3,and LEACH was 119.1.The obtained results maximized the lifetime and improved the overall performance of the CEER routing protocol.展开更多
Federated edge learning(FEEL)technology for vehicular networks is considered as a promising technology to reduce the computation workload while keeping the privacy of users.In the FEEL system,vehicles upload data to t...Federated edge learning(FEEL)technology for vehicular networks is considered as a promising technology to reduce the computation workload while keeping the privacy of users.In the FEEL system,vehicles upload data to the edge servers,which train the vehicles’data to update local models and then return the result to vehicles to avoid sharing the original data.However,the cache queue in the edge is limited and the channel between edge server and each vehicle is time-varying.Thus,it is challenging to select a suitable number of vehicles to ensure that the uploaded data can keep a stable cache queue in edge server while maximizing the learning accuracy.Moreover,selecting vehicles with different resource statuses to update data will affect the total amount of data involved in training,which further affects the model accuracy.In this paper,we propose a vehicle selection scheme,which maximizes the learning accuracy while ensuring the stability of the cache queue,where the statuses of all the vehicles in the coverage of edge server are taken into account.The performance of this scheme is evaluated through simulation experiments,which indicates that our proposed scheme can perform better than the known benchmark scheme.展开更多
Experts shared their opinions about current construction and development trend of future network during the forum through kinds of activities including keynote speeches。
The 5th China Future Network Development and Innovation Forum has been successfully held in Nanjing from December 10th to 11th,2015,which was co-hosted by the Chinese Academy of Engineering and Nanjing Government。
Future network has become a main focus of competitions among countries.In recent years,the United States,Japan and the EU have initiated a series of national projects of future network test facilities.Many renowned co...Future network has become a main focus of competitions among countries.In recent years,the United States,Japan and the EU have initiated a series of national projects of future network test facilities.Many renowned companies展开更多
Active networks are a new kind of packet-switched networks in which packets have code fragments that are executed on the intermediary nodes (routers). The code can extend or modify the foundation architecture of a net...Active networks are a new kind of packet-switched networks in which packets have code fragments that are executed on the intermediary nodes (routers). The code can extend or modify the foundation architecture of a network. In this paper, the authors present a novel active network architecture combined with advantages of two major active networks technology based on extensible services router. The architecture consists of extensible service router, active extensible components server and key distribution center (KDC). Users can write extensible service components with programming interface. At the present time, we have finished the extensible services router prototype system based on Highly Efficient Router Operating System (HEROS), active extensible components server and KDC prototype system based on Linux.展开更多
Over-the-top services and cloud services have created great challenges for telecom operators. To better meet the requirements of cloud services, we propose a decoupled network architecture. Software-defined networkin...Over-the-top services and cloud services have created great challenges for telecom operators. To better meet the requirements of cloud services, we propose a decoupled network architecture. Software-defined networking/network function virtualization （SDN/ NFV） will be vital in the construction of cloud-oriented broadband infrastructure, especially within data centers and for intercon nection between data centers. We also propose introducing SDN/NFV in the broadband access network in order to realize a virtu- alized residential gateway （VRG）. We discuss the deployment modes of VRG.展开更多
Because of the anonymity and openness of E-commerce, the on-line transaction and the selection of network resources meet new challenges. For this reason, a trust domain-based multi-agent model for network resource sel...Because of the anonymity and openness of E-commerce, the on-line transaction and the selection of network resources meet new challenges. For this reason, a trust domain-based multi-agent model for network resource selection is presented. The model divides the network into numbers of trust domains and prevents the inconsistency of information maintained by different agents through the periodical communication among the agents. The model enables consumers to receive the response from the agents much quicker because the trust values of participators are evalUated and updated dynamically and timely after the completion of each transaction. In order to make users choose the best matching services and give users with trusted services, the model takes into account the similarity between services and the service providers＇ recognition to the services. Finally, the model illustrates the effectiveness and feasibility according to the experiment.展开更多
SATech-01 is an experimental satellite for space science exploration and on-orbit demonstration of advanced technologies.The satellite is equipped with 16 experimental payloads and supports multiple working modes to m...SATech-01 is an experimental satellite for space science exploration and on-orbit demonstration of advanced technologies.The satellite is equipped with 16 experimental payloads and supports multiple working modes to meet the observation requirements of various payloads.Due to the limitation of platform power supply and data storage systems,proposing reasonable mission planning schemes to improve scientific revenue of the payloads becomes a critical issue.In this article,we formulate the integrated task scheduling of SATech-01 as a multi-objective optimization problem and propose a novel Fair Integrated Scheduling with Proximal Policy Optimization(FIS-PPO)algorithm to solve it.We use multiple decision heads to generate decisions for each task and design the action mask to ensure the schedule meeting the platform constraints.Experimental results show that FIS-PPO could push the capability of the platform to the limit and improve the overall observation efficiency by 31.5%compared to rule-based plans currently used.Moreover,fairness is considered in the reward design and our method achieves much better performance in terms of equal task opportunities.Because of its low computational complexity,our task scheduling algorithm has the potential to be directly deployed on board for real-time task scheduling in future space projects.展开更多
Multi‐agent reinforcement learning relies on reward signals to guide the policy networks of individual agents.However,in high‐dimensional continuous spaces,the non‐stationary environment can provide outdated experi...Multi‐agent reinforcement learning relies on reward signals to guide the policy networks of individual agents.However,in high‐dimensional continuous spaces,the non‐stationary environment can provide outdated experiences that hinder convergence,resulting in ineffective training performance for multi‐agent systems.To tackle this issue,a novel reinforcement learning scheme,Mutual Information Oriented Deep Skill Chaining(MioDSC),is proposed that generates an optimised cooperative policy by incorporating intrinsic rewards based on mutual information to improve exploration efficiency.These rewards encourage agents to diversify their learning process by engaging in actions that increase the mutual information between their actions and the environment state.In addition,MioDSC can generate cooperative policies using the options framework,allowing agents to learn and reuse complex action sequences and accelerating the convergence speed of multi‐agent learning.MioDSC was evaluated in the multi‐agent particle environment and the StarCraft multi‐agent challenge at varying difficulty levels.The experimental results demonstrate that MioDSC outperforms state‐of‐the‐art methods and is robust across various multi‐agent system tasks with high stability.展开更多
From July 2008 to August 2008, 72 leaf samples from 22 species and 81 soil samples in the nine natural forest ecosystems were collected, from north to south along the North-South Transect of Eastern China （NSTEC）. B...From July 2008 to August 2008, 72 leaf samples from 22 species and 81 soil samples in the nine natural forest ecosystems were collected, from north to south along the North-South Transect of Eastern China （NSTEC）. Based on these samples, we studied the geographical distribution patterns of vegetable water use efficiency （WUE） and nitrogen use efficiency （NUE）, and analyzed their relationship with environmental factors. The vegetable WUE and NUE were calculated through the measurement of foliar δ 13C and C/N of predominant species, respectively. The results showed： （1） vegetable WUE, ranging from 2.13 to 28.67 mg C g-1 H2O, increased linearly from south to north in the representative forest ecosystems along the NSTEC, while vegetable NUE showed an opposite trend, increasing from north to south, ranging from 12.92 to 29.60 g C g-1 N. （2） Vegetable WUE and NUE were dominantly driven by climate and significantly affected by soil nutrient factors. Based on multiple stepwise regression analysis, mean annual temperature, soil phosphorus concentration, and soil nitrogen concentration were responding for 75.5% of the variations of WUE （p0.001）. While, mean annual precipitation and soil phosphorus concentration could explain 65.7% of the change in vegetable NUE （p0.001）. Moreover, vegetable WUE and NUE would also be seriously influenced by atmospheric nitrogen deposition in nitrogen saturated ecosystems. （3） There was a significant trade-off relationship between vegetable WUE and NUE in the typical forest ecosystems along the NSTEC （p0.001）, indicating a balanced strategy for vegetation in resource utilization in natural forest ecosystems along the NSTEC. This study suggests that global change would impact the resource use efficiency of forest ecosystems. However, vegetation could adapt to those changes by increasing the use efficiency of shortage resource while decreasing the relatively ample one. But extreme impacts, such as heavy nitrogen deposition, would break this trade-off mechanism and give a dramatic disturbance to the ecosystem biogeochemical cycle.展开更多
BACKGROUND Colorectal cancer(CRC)is the second leading cause of all cancer related deaths in the United States and Europe.Although the incidence has been decreasing for individuals’≥50,it has been on the rise for in...BACKGROUND Colorectal cancer(CRC)is the second leading cause of all cancer related deaths in the United States and Europe.Although the incidence has been decreasing for individuals’≥50,it has been on the rise for individuals<50.AIM To identify potential risk factors for early-onset CRC.METHODS A population-based cohort analysis using a national database,Explorys,screened all patients with an active electronic medical record from January 2012 to December 2016 with a diagnosis of CRC.Subgroups were stratified based on age(25–49 years vs≥50 years).Demographics,comorbidities,and symptom profiles were recorded and compared between both age groups.Furthermore,the younger group was also compared with a control group consisting of individuals aged 25-49 years within the same timeframe without a diagnosis of CRC.Twentydata points for CRC related factors were analyzed to identify potential risk factors specific to early-onset CRC.RESULTS A total of 68860 patients were identified with CRC,of which 5710(8.3%)were younger than 50 years old,with 4140(73%)between 40-49 years of age.Multivariable analysis was reported using odds ratio(OR)with 95%CI and demonstrated that several factors were associated with an increased risk of CRC in the early-onset group versus the later-onset group.These factors included:African-American race(OR 1.18,95%CI:1.09-1.27,P<0.001),presenting symptoms of abdominal pain(OR 1.82,95%CI:1.72-1.92,P<0.001),rectal pain(OR 1.50,95%CI:1.28-1.77,P<0.001),altered bowel function(OR 1.12,95%CI:1.05-1.19,P=0.0005),having a family history of any cancer(OR 1.78,95%CI:1.67-1.90,P<0.001),gastrointestinal(GI)malignancy(OR 2.36,95%CI:2.18-2.55,P<0.001),polyps(OR 1.41,95%CI:1.08-1.20,P<0.001),and obesity(OR 1.14,95%CI:1.08-1.20,P<0.001).Comparing the early-onset cohort versus the control group,factors that were associated with an increased risk of CRC were:male gender(OR 1.34,95%CI:1.27-1.41),P<0.001),Caucasian(OR 1.48,95%CI:1.40-1.57,P<0.001)and African-American race(OR 1.25,95%CI:1.17-1.35,P<0.001),presenting symptoms of abdominal pain(OR 4.73,95%CI:4.49-4.98,P<0.001),rectal pain(OR 7.48,95%CI:6.42-8.72,P<0.001),altered bowel function(OR 5.51,95%CI:5.19-5.85,P<0.001),rectal bleeding(OR 9.83,95%CI:9.12-10.6,P<0.001),weight loss(OR 7.43,95%CI:6.77-8.15,P<0.001),having a family history of cancer(OR 11.66,95%CI:10.97-12.39,P<0.001),GI malignancy(OR 28.67,95%CI:26.64-30.86,P<0.001),polyps(OR 8.15,95%CI:6.31-10.52,P<0.001),tobacco use(OR 2.46,95%CI:2.33-2.59,P<0.001),alcohol use(OR 1.71,95%CI:1.62-1.80,P<0.001),presence of colitis(OR 4.10,95%CI:3.79-4.43,P<0.001),and obesity(OR 2.88,95%CI:2.74-3.04,P<0.001).CONCLUSION Pending further investigation,these potential risk factors should lower the threshold of suspicion for early CRC and potentially be used to optimize guidelines for early screening.展开更多
To cope with privacy leakage caused by multimedia outsourcing and sharing,data provenance is used to analyze leaked multimedia and provide reactive accountability.Existing schemes of multimedia provenance are based on...To cope with privacy leakage caused by multimedia outsourcing and sharing,data provenance is used to analyze leaked multimedia and provide reactive accountability.Existing schemes of multimedia provenance are based on watermarking protocols.In an outsourcing scenario,existing schemes face two severe challenges:1)when data leakage occurs,there exists a probability that data provenance results can be repudiated,in which case data provenance tracking fails;and 2)when outsourced data are shared,data encryption transfer causes key management burden outside the schemes,and privacy leakage threatens users.In this paper,we propose a novel data provenance scheme with an improved LUT-based fingerprinting protocol,which integrates an asymmetric watermarking protocol,robust watermark algorithm and homomorphic encryption and digital signatures to achieve full non-repudiation provenance.We build an in-scheme stream cipher to protect outsourced multimedia data from privacy leakage and complicated key management.Our scheme is also lightweight and easy to deploy.Extensive security and performance analysis compares our scheme with the state of the art.The results show that our scheme has not only better provenance security and data confidentiality but also higher efficiency for multimedia outsourcing,sharing and provenance.展开更多
基金supported in part by the National Natural Science Foundation of China(NSFC)under grant numbers U22A2007 and 62171010the Open project of Satellite Internet Key Laboratory in 2022(Project 3:Research on Spaceborne Lightweight Core Network and Intelligent Collaboration)the Beijing Natural Science Foundation under grant number L212003.
文摘With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)satellite networks.While due to the scarcity of bandwidth resources and dynamic topology of LEO satellites,the static SFC placement schemes may cause performance degradation,resource waste and even service failure.In this paper,we consider migration and establish an online migration model,especially considering the dynamic topology.Given the scarcity of bandwidth resources,the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as possible.Due to its NP-hardness,we propose a heuristic minimized dynamic SFC migration(MDSM)algorithm that only triggers the migration procedure when new SFCs are rejected.Simulation results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.
基金supported by Beijing Natural Science Foundation(L212029,L221009)the National Natural Science Foundation of China(62271043,62371033)the Ministry of Education of China(8091B032123).
文摘An emerging railway technology called smart railway promises to deliver higher transportation efficiency,enhanced comfort in services,and greater eco-friendliness.The smart railway is expected to integrate fifth-generation mobile communication(5G),Artificial Intelligence(AI),and other technologies,which poses new problems in the construction,operation and maintenance of railway wireless networks.Wireless Digital Twins(DTs),which have recently emerged as a new paradigm for the design of wireless networks,can address these problems and enable the whole lifecycle management of railway wireless networks.However,there are still many scientific issues and challenges for railway-oriented wireless DT.Relevant key technologies to solve these problems are introduced and described,including characterization of materials'physical-EM properties,autonomous reconstruction of Three-dimensional(3D)environment model,AI-empowered environmental cognition,Ray-Tracing(RT),model-based and AIbased RT acceleration,and generation of multi-spectra sensing data.Moreover,this paper presents our research results for each key technology and describes the wireless network planning and optimization system based on highperformance RT developed by our laboratory.This paper outlines the framework for realizing the wireless DT of smart railways,providing the direction for future research.
文摘As 5th Generation(5G)and Beyond 5G(B5G)networks become increasingly prevalent,ensuring not only networksecurity but also the security and reliability of the applications,the so-called network applications,becomesof paramount importance.This paper introduces a novel integrated model architecture,combining a networkapplication validation framework with an AI-driven reactive system to enhance security in real-time.The proposedmodel leverages machine learning(ML)and artificial intelligence(AI)to dynamically monitor and respond tosecurity threats,effectively mitigating potential risks before they impact the network infrastructure.This dualapproach not only validates the functionality and performance of network applications before their real deploymentbut also enhances the network’s ability to adapt and respond to threats as they arise.The implementation ofthis model,in the shape of an architecture deployed in two distinct sites,demonstrates its practical viability andeffectiveness.Integrating application validation with proactive threat detection and response,the proposed modeladdresses critical security challenges unique to 5G infrastructures.This paper details the model,architecture’sdesign,implementation,and evaluation of this solution,illustrating its potential to improve network securitymanagement in 5G environments significantly.Our findings highlight the architecture’s capability to ensure boththe operational integrity of network applications and the security of the underlying infrastructure,presenting asignificant advancement in network security.
基金supported by the Natural Science Foundation of Jiangsu Province(Grant No.BK20240613)Jiangsu Province’s“Innovation and Entrepreneurship Doctor”Program(Grant No.JSSCBS20230088)+4 种基金Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY224123)Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(Grant No.NY222112)Beijing Nova Program(Grant No.20240484696)Wenzhou Major Science and Technology Innovation Key Project(Grant No.ZG2020046)INNOVATION Program for Quantum Science and Technology(Grant No.2021ZD0303200)。
文摘The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential solution for this purpose,although continuous oscillation at super large incident angle remains challenging.In this work,we employ the CCA resonator to generate continuous oscillation within±20°angular misalignment of cavity mirror in experiment.On the basis of retroreflection theory,the retroreflectivity of a CCA is analyzed by using optical simulation software.Notably,the experiment verifies the advantage of using a CCA over a plane mirror in laser resonator,thereby providing a promising approach for ECDLs.The threshold characteristic curves measured at different incident angles in the experiment verify that the CCA possesses an obvious anti-angle misalignment performance.This research introduces an alternative solution of using CCA resonator instead of parallel plane cavity,thereby realizing an adjustment-free ECDL with enhanced mechanical stability.
基金supported by the National Key Research and Development Program of China[grant number 2022YFC3703003]the Energy Foundation Project[grant number G-2309-35044]the SinoNorwegian Project on Methane from Livestock Production and Waste Management(ChiNorCH4)[grant number CHN-2148,22/0011].
文摘The trends and characteristics of global CH_(4)emissions were analyzed using greenhouse gas data reported by both Annex I and non-Annex I countries under the United Nations Framework Convention on Climate Change(UNFCCC)from 1990 to 2021.The results show the following:(1)In 2021,the cumulative CH_(4)emissions from the 42 nations listed in Annex I of the UNFCCC amounted to 1871521.79 kt CO_(2)eq.The top 10 countries account for 82.0%of the total CH_(4)emissions.(2)Most Annex I countries showed a gradual decline in CH_(4)emissions over the period.In contrast,emissions from non-Annex I countries have increased year by year.Notably,CH_(4)emissions in the United States,the European Union,the Russian Federation,and Ukraine decreased by 14.0%,37.4%,24.0%,and 60.9%,respectively.(3)In 2020,the CH_(4)emissions of the agriculture,energy,waste treatment and LULUCF(land use,land-use change and forestry)sectors in Annex I countries were 72240.43,63863.51,41573.08,and 889019 million tons of CO_(2)eq,accounting for 38.6%,34.1%,22.2%,and 4.8%,respectively.Among non-Annex I countries,the main CH_(4)sources vary by country.In China and Mexico,energy and agriculture were the largest contributors,accounting for 44.8%and 40.2%in China,and 34.4%and 43.3%in Mexico,respectively.In India,Brazil,Nigeria,Argentina,and Vietnam,agriculture dominated,contributing 73.8%,75.8%,59.7%,60.3%,and 58.5%of total emissions,respectively.Indonesia was an exception,with waste treatment being the primary source,accounting for 64.8%of its total CH_(4)emissions.
文摘Internet of things and network densification bring significant challenges to uplink management.Only depending on optimization algorithm enhancements is not enough for uplink transmission.To control intercell interference,Fractional Uplink Power Control(FUPC)should be optimized from network-wide perspective,which has to find a better traffic distribution model.Conventionally,traffic distribution is geographic-based,and ineffective due to tricky locating efforts.This paper proposes a novel uplink power management framework for Self-Organizing Networks(SON),which firstly builds up pathloss-based traffic distribution model and then makes the decision of FUPC based on the model.PathLoss-based Traffic Distribution(PLTD)aggregates traffic based on the propagation condition of traffic that is defined as the pathloss between the position generating the traffic and surrounding cells.Simulations show that the improvement in optimization efficiency of FUPC with PLTD can be up to 40%compared to conventional GeoGraphic-based Traffic Distribution(GGTD).
基金supported by the National Research Foundation of Korea-Grant funded by the Korean Government(MSIT)-NRF-2020R1A2B5B02002478)supported by the Cluster grant R20143 of Zayed University,UAE.
文摘Underwater acoustic sensor networks(UWASNs)aim to find varied offshore ocean monitoring and exploration applications.In most of these applications,the network is composed of several sensor nodes deployed at different depths in the water.Sensor nodes located at depth on the seafloor cannot invariably communicate with nodes close to the surface level;these nodes need multihop communication facilitated by a suitable routing scheme.In this research work,a Cluster-based Cooperative Energy Efficient Routing(CEER)mechanism for UWSNs is proposed to overcome the shortcomings of the Co-UWSN and LEACH mechanisms.The optimal role of clustering and cooperation provides load balancing and improves the network profoundly.The simulation results using MATLAB show better performance of CEER routing protocol in terms of various parameters as compared to Co-UWSN routing protocol,i.e.,the average end-to-end delay of CEER was 17.39,Co-UWSN was 55.819 and LEACH was 70.08.In addition,the average total energy consumption of CEER was 9.273,Co-UWSN was 12.198,and LEACH was 45.33.The packet delivery ratio of CEER was 53.955,CO-UWSN was 42.047,and LEACH was 30.31.The stability period CEER was 130.9,CO-UWSN was 129.3,and LEACH was 119.1.The obtained results maximized the lifetime and improved the overall performance of the CEER routing protocol.
基金supported in part by the National Natural Science Foundation of China(No.61701197)in part by the open research fund of State Key Laboratory of Integrated Services Networks(No.ISN23-11)+3 种基金in part by the National Key Research and Development Program of China(No.2021YFA1000500(4))in part by the 111 Project(No.B23008)in part by the Future Network Scientific Research Fund Project(FNSRFP2021-YB-11)in part by the project of Changzhou Key Laboratory of 5G+Industrial Internet Fusion Application(No.CM20223015)。
文摘Federated edge learning(FEEL)technology for vehicular networks is considered as a promising technology to reduce the computation workload while keeping the privacy of users.In the FEEL system,vehicles upload data to the edge servers,which train the vehicles’data to update local models and then return the result to vehicles to avoid sharing the original data.However,the cache queue in the edge is limited and the channel between edge server and each vehicle is time-varying.Thus,it is challenging to select a suitable number of vehicles to ensure that the uploaded data can keep a stable cache queue in edge server while maximizing the learning accuracy.Moreover,selecting vehicles with different resource statuses to update data will affect the total amount of data involved in training,which further affects the model accuracy.In this paper,we propose a vehicle selection scheme,which maximizes the learning accuracy while ensuring the stability of the cache queue,where the statuses of all the vehicles in the coverage of edge server are taken into account.The performance of this scheme is evaluated through simulation experiments,which indicates that our proposed scheme can perform better than the known benchmark scheme.
文摘Experts shared their opinions about current construction and development trend of future network during the forum through kinds of activities including keynote speeches。
文摘The 5th China Future Network Development and Innovation Forum has been successfully held in Nanjing from December 10th to 11th,2015,which was co-hosted by the Chinese Academy of Engineering and Nanjing Government。
文摘Future network has become a main focus of competitions among countries.In recent years,the United States,Japan and the EU have initiated a series of national projects of future network test facilities.Many renowned companies
文摘Active networks are a new kind of packet-switched networks in which packets have code fragments that are executed on the intermediary nodes (routers). The code can extend or modify the foundation architecture of a network. In this paper, the authors present a novel active network architecture combined with advantages of two major active networks technology based on extensible services router. The architecture consists of extensible service router, active extensible components server and key distribution center (KDC). Users can write extensible service components with programming interface. At the present time, we have finished the extensible services router prototype system based on Highly Efficient Router Operating System (HEROS), active extensible components server and KDC prototype system based on Linux.
文摘Over-the-top services and cloud services have created great challenges for telecom operators. To better meet the requirements of cloud services, we propose a decoupled network architecture. Software-defined networking/network function virtualization （SDN/ NFV） will be vital in the construction of cloud-oriented broadband infrastructure, especially within data centers and for intercon nection between data centers. We also propose introducing SDN/NFV in the broadband access network in order to realize a virtu- alized residential gateway （VRG）. We discuss the deployment modes of VRG.
基金Supported by the National Natural Science Foundation of China （No. 60873203 ）, the Natural Science Foundation of Hebei Province （No F2008000646） and the Guidance Program of the Department of Science and Technology in Hebei Province （No. 72135192）.
文摘Because of the anonymity and openness of E-commerce, the on-line transaction and the selection of network resources meet new challenges. For this reason, a trust domain-based multi-agent model for network resource selection is presented. The model divides the network into numbers of trust domains and prevents the inconsistency of information maintained by different agents through the periodical communication among the agents. The model enables consumers to receive the response from the agents much quicker because the trust values of participators are evalUated and updated dynamically and timely after the completion of each transaction. In order to make users choose the best matching services and give users with trusted services, the model takes into account the similarity between services and the service providers＇ recognition to the services. Finally, the model illustrates the effectiveness and feasibility according to the experiment.
基金supported by the Strategic Priority Program on Space Science,Chinese Academy of Sciences。
文摘SATech-01 is an experimental satellite for space science exploration and on-orbit demonstration of advanced technologies.The satellite is equipped with 16 experimental payloads and supports multiple working modes to meet the observation requirements of various payloads.Due to the limitation of platform power supply and data storage systems,proposing reasonable mission planning schemes to improve scientific revenue of the payloads becomes a critical issue.In this article,we formulate the integrated task scheduling of SATech-01 as a multi-objective optimization problem and propose a novel Fair Integrated Scheduling with Proximal Policy Optimization(FIS-PPO)algorithm to solve it.We use multiple decision heads to generate decisions for each task and design the action mask to ensure the schedule meeting the platform constraints.Experimental results show that FIS-PPO could push the capability of the platform to the limit and improve the overall observation efficiency by 31.5%compared to rule-based plans currently used.Moreover,fairness is considered in the reward design and our method achieves much better performance in terms of equal task opportunities.Because of its low computational complexity,our task scheduling algorithm has the potential to be directly deployed on board for real-time task scheduling in future space projects.
基金National Natural Science Foundation of China,Grant/Award Number:61872171The Belt and Road Special Foundation of the State Key Laboratory of Hydrology‐Water Resources and Hydraulic Engineering,Grant/Award Number:2021490811。
文摘Multi‐agent reinforcement learning relies on reward signals to guide the policy networks of individual agents.However,in high‐dimensional continuous spaces,the non‐stationary environment can provide outdated experiences that hinder convergence,resulting in ineffective training performance for multi‐agent systems.To tackle this issue,a novel reinforcement learning scheme,Mutual Information Oriented Deep Skill Chaining(MioDSC),is proposed that generates an optimised cooperative policy by incorporating intrinsic rewards based on mutual information to improve exploration efficiency.These rewards encourage agents to diversify their learning process by engaging in actions that increase the mutual information between their actions and the environment state.In addition,MioDSC can generate cooperative policies using the options framework,allowing agents to learn and reuse complex action sequences and accelerating the convergence speed of multi‐agent learning.MioDSC was evaluated in the multi‐agent particle environment and the StarCraft multi‐agent challenge at varying difficulty levels.The experimental results demonstrate that MioDSC outperforms state‐of‐the‐art methods and is robust across various multi‐agent system tasks with high stability.
基金National Natural Science Foundation of China No.30590381 No.31000211 National Basic Research Program of China No.2010CB833504
文摘From July 2008 to August 2008, 72 leaf samples from 22 species and 81 soil samples in the nine natural forest ecosystems were collected, from north to south along the North-South Transect of Eastern China （NSTEC）. Based on these samples, we studied the geographical distribution patterns of vegetable water use efficiency （WUE） and nitrogen use efficiency （NUE）, and analyzed their relationship with environmental factors. The vegetable WUE and NUE were calculated through the measurement of foliar δ 13C and C/N of predominant species, respectively. The results showed： （1） vegetable WUE, ranging from 2.13 to 28.67 mg C g-1 H2O, increased linearly from south to north in the representative forest ecosystems along the NSTEC, while vegetable NUE showed an opposite trend, increasing from north to south, ranging from 12.92 to 29.60 g C g-1 N. （2） Vegetable WUE and NUE were dominantly driven by climate and significantly affected by soil nutrient factors. Based on multiple stepwise regression analysis, mean annual temperature, soil phosphorus concentration, and soil nitrogen concentration were responding for 75.5% of the variations of WUE （p0.001）. While, mean annual precipitation and soil phosphorus concentration could explain 65.7% of the change in vegetable NUE （p0.001）. Moreover, vegetable WUE and NUE would also be seriously influenced by atmospheric nitrogen deposition in nitrogen saturated ecosystems. （3） There was a significant trade-off relationship between vegetable WUE and NUE in the typical forest ecosystems along the NSTEC （p0.001）, indicating a balanced strategy for vegetation in resource utilization in natural forest ecosystems along the NSTEC. This study suggests that global change would impact the resource use efficiency of forest ecosystems. However, vegetation could adapt to those changes by increasing the use efficiency of shortage resource while decreasing the relatively ample one. But extreme impacts, such as heavy nitrogen deposition, would break this trade-off mechanism and give a dramatic disturbance to the ecosystem biogeochemical cycle.
文摘BACKGROUND Colorectal cancer(CRC)is the second leading cause of all cancer related deaths in the United States and Europe.Although the incidence has been decreasing for individuals’≥50,it has been on the rise for individuals<50.AIM To identify potential risk factors for early-onset CRC.METHODS A population-based cohort analysis using a national database,Explorys,screened all patients with an active electronic medical record from January 2012 to December 2016 with a diagnosis of CRC.Subgroups were stratified based on age(25–49 years vs≥50 years).Demographics,comorbidities,and symptom profiles were recorded and compared between both age groups.Furthermore,the younger group was also compared with a control group consisting of individuals aged 25-49 years within the same timeframe without a diagnosis of CRC.Twentydata points for CRC related factors were analyzed to identify potential risk factors specific to early-onset CRC.RESULTS A total of 68860 patients were identified with CRC,of which 5710(8.3%)were younger than 50 years old,with 4140(73%)between 40-49 years of age.Multivariable analysis was reported using odds ratio(OR)with 95%CI and demonstrated that several factors were associated with an increased risk of CRC in the early-onset group versus the later-onset group.These factors included:African-American race(OR 1.18,95%CI:1.09-1.27,P<0.001),presenting symptoms of abdominal pain(OR 1.82,95%CI:1.72-1.92,P<0.001),rectal pain(OR 1.50,95%CI:1.28-1.77,P<0.001),altered bowel function(OR 1.12,95%CI:1.05-1.19,P=0.0005),having a family history of any cancer(OR 1.78,95%CI:1.67-1.90,P<0.001),gastrointestinal(GI)malignancy(OR 2.36,95%CI:2.18-2.55,P<0.001),polyps(OR 1.41,95%CI:1.08-1.20,P<0.001),and obesity(OR 1.14,95%CI:1.08-1.20,P<0.001).Comparing the early-onset cohort versus the control group,factors that were associated with an increased risk of CRC were:male gender(OR 1.34,95%CI:1.27-1.41),P<0.001),Caucasian(OR 1.48,95%CI:1.40-1.57,P<0.001)and African-American race(OR 1.25,95%CI:1.17-1.35,P<0.001),presenting symptoms of abdominal pain(OR 4.73,95%CI:4.49-4.98,P<0.001),rectal pain(OR 7.48,95%CI:6.42-8.72,P<0.001),altered bowel function(OR 5.51,95%CI:5.19-5.85,P<0.001),rectal bleeding(OR 9.83,95%CI:9.12-10.6,P<0.001),weight loss(OR 7.43,95%CI:6.77-8.15,P<0.001),having a family history of cancer(OR 11.66,95%CI:10.97-12.39,P<0.001),GI malignancy(OR 28.67,95%CI:26.64-30.86,P<0.001),polyps(OR 8.15,95%CI:6.31-10.52,P<0.001),tobacco use(OR 2.46,95%CI:2.33-2.59,P<0.001),alcohol use(OR 1.71,95%CI:1.62-1.80,P<0.001),presence of colitis(OR 4.10,95%CI:3.79-4.43,P<0.001),and obesity(OR 2.88,95%CI:2.74-3.04,P<0.001).CONCLUSION Pending further investigation,these potential risk factors should lower the threshold of suspicion for early CRC and potentially be used to optimize guidelines for early screening.
基金The authors would like to thank the anonymous referees for their valuable comments and helpful suggestions.The work is supported by the National Key Research and Development Program of China(No.2016YFB0800402)the National Natural Science Foundation of China(No.U1405254,No.U1536207).
文摘To cope with privacy leakage caused by multimedia outsourcing and sharing,data provenance is used to analyze leaked multimedia and provide reactive accountability.Existing schemes of multimedia provenance are based on watermarking protocols.In an outsourcing scenario,existing schemes face two severe challenges:1)when data leakage occurs,there exists a probability that data provenance results can be repudiated,in which case data provenance tracking fails;and 2)when outsourced data are shared,data encryption transfer causes key management burden outside the schemes,and privacy leakage threatens users.In this paper,we propose a novel data provenance scheme with an improved LUT-based fingerprinting protocol,which integrates an asymmetric watermarking protocol,robust watermark algorithm and homomorphic encryption and digital signatures to achieve full non-repudiation provenance.We build an in-scheme stream cipher to protect outsourced multimedia data from privacy leakage and complicated key management.Our scheme is also lightweight and easy to deploy.Extensive security and performance analysis compares our scheme with the state of the art.The results show that our scheme has not only better provenance security and data confidentiality but also higher efficiency for multimedia outsourcing,sharing and provenance.
