Service Function Chain Migration in LEO Satellite Networks

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.

Dynamic Backup Sharing Scheme of Service Function Chains in NFV

Service function chains(SFC)mapping takes the responsibility for managing virtual network functions(VNFs).In SFC mapping,existing solutions duplicate VNFs with redundant instances to provide high availability in response to failures.However,as a compromise,these solutions result in high resource consumption due to device maintenance.In this paper,we propose a novel method named dynamic backup sharing(DBS)that allows SFCs to dynamically share backups to reduce resource consumption.DBS formulates the problem of sharing backups among different VNFs as an integer linear programming(ILP).Thereafter,we design a novel online algorithm based on dynamic programming to solve the problem.The experimental results indicate that DBS outperforms state-ofthe-art works by reducing resource consumption and improving the number of accepted requests.

Value Assessment of Ecosystem Service Function of Ecological Public Welfare Forests in Wenchang City

Based on the measurement parameters and index in the Specifications for Assessment of Forest Ecosystem Services in China(LY/T 1721-2008),the value of ecological service functions of ecological public welfare forest in Wenchang City was evaluated and analyzed.The results show that the total value of ecosystem service function of ecological public welfare forests in Wenchang City is about 4.020 billion yuan,of which storage capacity,water purification,soil fixation,fertilizer(N,P and K fertilizer) conservation,carbon sequestration,oxygen release,forest nutrient accumulation,providing anion,absorbing SO_2,absorbing fluoride,absorbing NxO,absorbing soil heavy metals,dust retention,noise reduction,sterilization,forest protection,forest biodiversity protection,and forest recreation(ecological tourism) are about 1.510 billion,582.256 million,3.769 million,268.220 million,116.360 million,2.747 million,22.682 million,42.817 million,1.722 million,74,600,131,900,187.918 million,77.409 million,28.721 million,43.090 million,180.696 million,571.036 million,and 108.677 million yuan

Multi-Path Service Function Chaining for Mobile Surveillance of Animal Husbandry

Animal husbandry is the pillar industry in some ethnic areas of China.However,the communication/networking infrastructure in these areas is often underdeveloped,thus the difficulty in centralized management,and challenges for the effective monitoring.Considering the dynamics of the field monitoring environment,as well as the diversity and mobility of monitoring targets,traditional WSN(Wireless Sensor Networks)or IoT(Internet of Things)is difficult to meet the surveillance needs.Mobile surveillance that features the collaboration of various functions(camera,sensing,image recognition,etc.)deployed on mobile devices is desirable in a volatile wireless environment.This paper proposes the service function chaining for mobile surveillance of animal husbandry,which orchestrates multi-path multifunction(MPMF)chains to help mobile devices to collaborate in complex surveillance tasks,provide backup chains in case the primary service function chain fails due to mobility,signal strength,obstacle,etc.,and make up for the defects of difficult deployment of monitoring facilities in ethnic areas.MPMF algorithmmodels both mobile devices and various functions deployed on them as abstract graph nodes,so that chains that are required to traverse various functions and hosting mobile devices can be orchestrated in a single graphbased query through modified and adapted Dijkstra-like algorithms,with their cost ordered automatically.Experiment results show that the proposed MPMF algorithm finds multiple least-costly chains that traverse demanded functions in a timely fashion on Raspberry Pi-equipped mobile devices.

Research on Service Function Chain Orchestrating Algorithm Based on SDN and NFV

Software defined network(SDN)and network function virtualization(NFV)have become a new paradigm of a new generation of network architecture.SDN and NFV can effectively improve the flexibility of deploying and managing service function chains(SFCs).By combining SDN and NFV and applying them to the resource orchestration problem of SFC deployment,the three-tier architecture consisting of SDN controller,network function virtualization and physical underlying computing resource layer in the process of heterogeneous network resource mapping is considered.And an optimization algorithm for active control resources based on SDN and NFV is proposed.Firstly,the user’s utility is modeled by the multistandard aggregated multi-criteria utility algorithm,and the optimization goal is transformed into the problem of maximizing the user’s utility.Then the controller,based on the algorithm’s prediction of the future state and realtime monitoring of the network utilization,makes decisions and issues control commands for the arriving SFC requests,based on which it occupies the underlying resources held by the virtualized network function(VNF).The simulation results show that,compared with the static timing resource allocation algorithm,the active control resource deployment algorithm proposed in the article has better performance in terms of resource utilization,acceptance rate,and user creation utility.

An Adaptive Hybrid Optimization Strategy for Resource Allocation in Network Function Virtualization

With the rapid development of Network Function Virtualization(NFV),the problem of low resource utilizationin traditional data centers is gradually being addressed.However,existing research does not optimize both localand global allocation of resources in data centers.Hence,we propose an adaptive hybrid optimization strategy thatcombines dynamic programming and neural networks to improve resource utilization and service quality in datacenters.Our approach encompasses a service function chain simulation generator,a parallel architecture servicesystem,a dynamic programming strategy formaximizing the utilization of local server resources,a neural networkfor predicting the global utilization rate of resources and a global resource optimization strategy for bottleneck andredundant resources.With the implementation of our local and global resource allocation strategies,the systemperformance is significantly optimized through simulation.

A Preliminary Exploration of the Functional Value Assessment of Ecosystem Services in Aral City

Using the principles and methods of eco-economics as the research object,Aral City comprehensively expounds the ecological service functions such as ecosystem regulation of climate,carbon sequestration,soil conservation,water conservation and purification environment,and evaluates its economic value.The total value of the estimated 2021 is 1303.65 million yuan.At the same time,the importance of ecological service functions of urban ecosystems,from large to small,is to sequester carbon and release oxygen,purify the environment,maintain soil,conserd water sources,regulate the climate.The ecosystem service function which needs to be paid attention to in the concept of ecological construction and restoration of the next stage of ecological construction in Aral City.

Distributed Matching Theory-Based Task Re-Allocating for Heterogeneous Multi-UAV Edge Computing

Many efforts have been devoted to efficient task scheduling in Multi-Unmanned Aerial Vehicle(UAV)edge computing.However,the heterogeneity of UAV computation resource,and the task re-allocating between UAVs have not been fully considered yet.Moreover,most existing works neglect the fact that a task can only be executed on the UAV equipped with its desired service function(SF).In this backdrop,this paper formulates the task scheduling problem as a multi-objective task scheduling problem,which aims at maximizing the task execution success ratio while minimizing the average weighted sum of all tasks’completion time and energy consumption.Optimizing three coupled goals in a realtime manner with the dynamic arrival of tasks hinders us from adopting existing methods,like machine learning-based solutions that require a long training time and tremendous pre-knowledge about the task arrival process,or heuristic-based ones that usually incur a long decision-making time.To tackle this problem in a distributed manner,we establish a matching theory framework,in which three conflicting goals are treated as the preferences of tasks,SFs and UAVs.Then,a Distributed Matching Theory-based Re-allocating(DiMaToRe)algorithm is put forward.We formally proved that a stable matching can be achieved by our proposal.Extensive simulation results show that Di Ma To Re algorithm outperforms benchmark algorithms under diverse parameter settings and has good robustness.

Identifying the priority areas for enhancing the ecosystem services in hilly and mountainous areas of southern China

Ecosystem services can be enhanced through ecological restoration,industrial structure adjustment,land-use optimization,and agricultural and forestry ecosystem transformation.The ecosystem services in hilly and mountainous areas of southern China are crucially needed to be enhanced since these regions are important ecological functional zones in China.However,due to its large area,it is not possible to simultaneously upgrade the ecosystem services for all areas,and therefore,priority areas need to be selected to individually upgrade the ecosystem service function.In this study,via an approach of combining remote sensing,geographic information system,and spatial statistics,we identify the priority areas that need to be upgraded based on the analysis of ecological sensitivity,importance of ecosystem service function,and decreased degree in ecosystem services.For five counties in hilly and mountainous areas of southern China,only less than 2% of the total area was identified as the first priority area;its land-use compositions were analyzed and recommendations on how to enhance ecosystem service were suggested.This approach overcomes the conflict and contradiction issues associated with identifying priority areas in previous studies and solves the problems of high cost or difficult implementation of priority areas.

Optimize the Deployment and Integration for Multicast-Oriented Virtual Network Function Tree

Due to the development of network technology,the number of users is increasing rapidly,and the demand for emerging multicast services is becoming more and more abundant,traffic data is increasing day by day,network nodes are becoming denser,network topology is becoming more complex,and operators’equipment operation and maintenance costs are increasing.Network functions virtualization multicast issues include building a traffic forwarding topology,deploying the required functions,and directing traffic.Combining the two is still a problem to be studied in depth at present,and this paper proposes a two-stage solution where the decisions of these two stages are interdependent.Specifically,this paper decouples multicast traffic forwarding and function delivery.The minimum spanning tree of traffic forwarding is constructed by Steiner tree,and the traffic forwarding is realized by Viterbi-algorithm.Use a general topology network to examine network cost and service performance.Simulation results show that this method can reduce overhead and delay and optimize user experience.

SFC Design and VNF Placement Based on Traffic Volume Scaling and VNF Dependency in 5G Networks

The development of Fifth-Generation(5G)mobile communication technology has remarkably promoted the spread of the Internet of Things(IoT)applications.As a promising paradigm for IoT,edge computing can process the amount of data generated by mobile intelligent devices in less time response.Network Function Virtualization(NFV)that decouples network functions from dedicated hardware is an important architecture to implement edge computing,deploying heterogeneous Virtual Network Functions(VNF)(such as computer vision,natural language processing,intelligent control,etc.)on the edge service nodes.With the NFV MANO(Management and Orchestration)framework,a Service Function Chain(SFC)that contains a set of ordered VNFs can be constructed and placed in the network to offer a customized network service.However,the procedure of NFV orchestration faces a technical challenge in minimizing the network cost of VNF placement due to the complexity of the changing effect of traffic volume and the dependency on theVNFrelationship.To this end,we jointly optimize SFC design and VNF placement to minimize resource cost while taking account of VNF dependency and traffic volume scaling.First,the problem is formulated as an Integer Linear Programming(ILP)model and proved NPhard by reduction from Hamiltonian Cycle problem.Then we proposed an efficient heuristic algorithm called Traffic Aware and Interdependent VNF Placement(TAIVP)to solve the problem.Compared with the benchmark algorithms,emulation results show that our algorithm can reduce network cost by 10.2%and increase service request acceptance rate by 7.6%on average.

Dynamic Security SFC Branching Path Selection Using Deep Reinforcement Learning

Security service function chaining(SFC)based on software-defined networking(SDN)and network function virtualization(NFV)technology allows traffic to be forwarded sequentially among different security service functions to achieve a combination of security functions.Security SFC can be deployed according to requirements,but the current SFC is not flexible enough and lacks an effective feedback mechanism.The SFC is not traffic aware and the changes of traffic may cause the previously deployed security SFC to be invalid.How to establish a closed-loop mechanism to enhance the adaptive capability of the security SFC to malicious traffic has become an important issue.Our contribution is threefold.First,we propose a secure SFC path selection framework.The framework can accept the feedback results of traffic and security service functions in SFC,and dynamically select the opti-mal path for SFC based on the feedback results.It also realizes the automatic deployment of paths,forming a complete closed loop.Second,we expand the protocol of SFC to realize the security SFC with branching path,which improve flexibility of security SFC.Third,we propose a deep reinforcement learning-based dynamic path selection method for security SFC.It infers the optimal branching path by analyzing feedback from the security SFC.We have experimented with Distributed Denial of Service(DDoS)attack detection modules as security service functions.Experimental results show that our proposed method can dynamically select the optimal branching path for a security SFC based on traffic features and the state of the SFC.And it improves the accuracy of the overall malicious traffic detection of the security SFC and significantly reduces the latency and overall load of the SFC.

Thoughts and Practice of Ecological Protection and Restoration of Mountains, Rivers, Forests, Farmlands, Lakes and Grasslands

The report of the 19th National Congress of the Communist Party of China stated that it was necessary to establish and practice the concept that lucid waters and lush mountains are invaluable assets,treat the ecological environment as life,and coordinate the management of mountains,rivers,forests,farmlands,lakes and grasslands.In recent years,China has organized a series of pilot projects for the ecological protection and restoration of mountains,rivers,forests,farmlands,lakes and grasslands,breaking the boundary between administrative divisions,departmental management and ecological elements,and implementing conservation and restoration oriented towards the improvement of ecosystem services,so as to solve the problem of the lack of overall planning for ecological protection and restoration projects and the separated management of ecological elements.This study systematically elaborated the theoretical basis and connotation characteristics of ecological protection and restoration of mountains,rivers,forests,farmlands,lakes and grasslands.It proposed the implementation path of ecological protection and restoration project of mountains,rivers,forests,farmlands,lakes and grasslands by taking the water source conservation area of Beijing-Tianjin-Hebei as a case,so as to provide reference for the implementation and decision-making management of ecological protection and restoration projects in various regions.

Advances in Research on Urban Green Spaces from the Perspective of Urban Geography

The construction of urban green space has attracted extensive attention of researchers under the background of urban sustainable development and ecological civilization construction.The research of urban green space involves ecology,geography,economics,sociology and other disciplines,among which geography has played an important role in promoting the study and practice of green space in terms of research perspectives,methods and techniques,planning and management.In this paper,the important role of urban geography in green space research is analyzed from defi nition,classifi cation to multidisciplinary background,and the research and practice progress of green space in urban geography are summarized in four aspects:characteristics and division of green space,relationship between green space and urban regional structure,service function of urban green space,and the relationship between green space and urban development.Finally,the practical achievements of green space research are illustrated from the perspective of urban geography.

Hierarchy of Rural Localities in the Niakhar Area (Fatick, Senegal)

Although the study of the hierarchy of localities presents an important social and economic stake, studies focused on the hierarchy of rural localities are relatively weak, especially in Africa. It is important to highlight the hierarchy of rural areas in order to reveal poles that can support sustainable growth. Our main objective is to study the hierarchy of rural localities in the Niakhar area, using a geographic approach. The data come from the Niakhar demographic, epidemiological and environmental observatory database and the Niakhar Atlas project of the French Research Institute for Development (IRD). The net flow method, the primacy index, the median population threshold method and the measurement of the correlation between level of centrality and population size are used to analyze the data. Our study allowed us to determine the main types of centrality and to establish the hierarchy of rural localities in the Niakhar zone. It also highlighted the strong correlation between the rank of localities and the size of the population of the latter. The main contribution of our work is to have highlighted, in order, the structuring localities of the rural space of the Niakhar area, by combining several indicators of centrality.

Cryospheric water regime by its functions and services in China

The terrestrial cryosphere functions to provide critical freshwater and serve societies and ecosystems,driving nature's contributions to people(NCP).This becomes increasingly important for the oasis areas in Northwest China.The cryospheric meltwater is in demand to support the economy and reduce poverty,accompanied by growing requirements to protect the environment.We intend to investigate the contributions of cryospheric meltwater by analyzing the spatial functions and services pertinent to provisioning meltwater in China.Based on the currently available datasets during the 2000s of glaciers,snow cover,and permafrost,spatial clustering was utilized to analyze the contributions at the third-level basin scale.Further assessment is carried out for the exposure of primary,secondary,and tertiary industrial sectors to cryospheric meltwater,which reflects the spatiality of potential services that cryospheric meltwater may provide.In results,we spatially cluster the contribution of cryospheric meltwater into six function zones and twenty-seven sub-zones,in association with the degree of their reliance on glaciers,snow cover,and permafrost.Considering the sector's exposure,we further spatially cluster the contribution areas into eleven service zones concerning the potential service of cryospheric meltwater.Generally,the cryosphere contributes approximately 8.3%of the total water resource in China,with function zones mainly distributed in northeastern China,Qinghai—Tibet Plateau(QTP),and other arid regions of Northwest China with various significance.The overall contribution ratios of the glacier,snow cover,and permafrost to cryospheric meltwater are about 35.6%,56.5%,and 7.9%,respectively.By looking into the service zones,the cryospheric meltwater mainly contributes to the primary industry in Northwest China and QTP,even though it has less significant effects on all other industrial sectors,while the services to the ecosystem are mainly located in QTP and high mountain regions.The results offer an overarching view on the contributions of cryospheric meltwater in China.

Cryosphere water resources supply function and service in China

With global warming and rapid shrinkage of the cryosphere,the decreasing cryosphere water resources(CWR)supply function would weaken its service and then affect local economic development and implement of United Nations Sustainable Development Goals(SDGs)in the world,but how does the CWR supply affect its service and their variations in the past and future are still not clear at present.In this study,the past dynamics(1960-2020),current situation(2010s)and projected changes(2020-2100)of CWR in China were assessed by calculating the meltwater from glacier,snow cover and the ground ice of permafrost under Representative Concentration Pathways scenarios(RCP2.6,RCP4.5,and RCP8.5).Combined with projected data of population and economy,the CWR service potential was also estimated in the 2030s,2050s and 2090s under scenarios of Shared Socioeconomic Pathways(SSP1,SSP2,and SSP5).The annual CWR in China is about 310.7×10^(9)m^(3) in the 2010s,with glacier runoff,snowmelt,and ground ice meltwater accounting for 24.1%,72.7%and 3.2%,respectively.Under SSP1-RCP2.6,the quantity of CWR was projected to decline by 14%-18%over the next 80 years,and the service potential would reach the peak in 2100.While under SSP5-RCP8.5,CWR would be reduced by 40%by 2100,and the service would gradually decline from 2050.The study of CWR is of great significance for water security,sustainable development and risk avoidance in the arid endorheic region.

中国重要农业文化遗产的空间分布特征及其差异性管理策略

Climate change and rapid urbanization pose significant challenges to the conservation and management of agricultural heritage systems,including decline in agricultural land,loss of labor,and ecosystem degradation.Although existing studies have proposed general strategies with theoretical guidance and specific strategies for particular systems to promote the conservation of agricultural heritage systems,there remains a large knowledge gap in effective and differentiated management strategies at the regional level.This is especially so in China because of the clear regional differences in the natural and socioeconomic conditions of the widely distributed China Nationally Important Agricultural Heritage Systems(China-NIAHS).In this study,we integrated multi-source data and spatial analysis to reveal the distribution characteristics of existing China-NIAHS and proposed differentiated management strategies.Results show that there are four clustering distribution zones of China-NIAHS,i.e.,the northwest clustering zone west of the Heihe-Tengchong Line(ZoneⅠ),the clustering belt with‘Northeast-Hebei-Shandong'as core(ZoneⅡ),the Yangtze River Delta clustering zone(ZoneⅢ),and the Hunan-Chongqing-Yunnan-Guizhou clustering zone(ZoneⅣ).Different management strategies are proposed for the China-NIAHS in each clustering zone.Specifically,ZoneⅠshould focus on maintaining their ecological functions and services,while ZoneⅡshould aim for livelihood supply,sustainable resource use,and ecological protection.For ZoneⅢ,rapid urbanization could become a positive driving force for China-NIAHS conservation through sustainable tourism and reasonable urban zoning.ZoneⅣshould emphasize the mutual support between characteristic product development and the brand effect of the China-NIAHS.These findings will help establish regional and targeted management strategies for China-NIAHS and provide a reference for the conservation of agricultural heritage systems in other countries.

Evaluation of ecosystem service of straw return to soil in a wheat field of China

Crop straw is an important natural resource in China because it is rich in nutrients.When returned to fields after harvests,the straw can improve soil quality and the next crop’s yield.Evaluating the economic values of the main ecological services of a farmland ecosystem while implementing the straw return technique can be a more systematic and comprehensive approach to better understand the contribution of straw return to the development of ecological agriculture.Based on the data of a field experiment established in 2010 with varying numbers of years of straw return,four ecological services,i.e.,agricultural product and industrial raw materials,atmospheric regulation and purification,soil nutrient accumulation,and water conservation,were selected to estimate a net ecosystem service value(ESV)of a wheat field’s ecosystem services.Agro-ecosystem service appraisal theories were applied to estimate the economic value of each service.Results showed that straw returning improved the total ESV in the wheat system.Compared to the no straw return treatment,1 year,3 years,5 years or 7 years of straw returning altered the economic value of the agricultural product and industrial raw materials(EVAIM)by-5.93%to 7.84%and improved atmospheric regulation(EVAR)by 13.66%-30.80%,soil nutrient accumulation(EVSNA)by 59.87%-233.31%and water conservation(EVWC)by 2.60%-13.26%.The total ESV of wheat plots with 1-7 years of straw returning was 3.67%-27.41%higher than that with no straw return,and the total ESV increased with the increase in years of straw return.The proportion of EVAIM out of the total ESV in this wheat field system was highest(accounted for 47.09%-55.64%),followed by EVAR and EVWC.The value of EVSNA was the lowest.However,the proportion of EVSNA was higher than that of water conservation after the fifth year of straw return.In general,the adoption of continuous straw returning in a wheat field ecosystem is ecologically valuable.The results can inform the development and implementation of ecological compensation policies involving straw return.

Evaluation of Loss of Degraded Farmland Ecosystem Services in Tibet, China

Four environmemtal service functions of wheat, barley and rape ecosystem are evaluated in material production, air adjustment (including carbon dioxide fixation and oxygen release in Tibetan Autonomous Region), water conservation, and nutrient recycling. Based on it the economic loss of environment due to desertification is valued. The results show that the service functions of farmland ecosystem in Tibet are totally valued at 4 436. 2 × 106 yuan, the value of each service function is ordered as: air adjustment 2 070.2× 106 yuan (46.67%), material production 2 011. 1× 106 yuan (45.33%), nutrient recycling 193. 1×106 yuan (4.35%), and water conservation 161. 8×106 yuan (3.65%). The total area of wheat, barley and rape in Tibet is over 189 700 ha, and the service function of farmland ecosystem is valued at 23 386 yuan/ha per year. The degraded area of arable land in Tibet is about 1 082 ha per year, equivalent to the annual loss of farmland ecosystem service value of 25.3×106 yuan. Over the past 30 years the total loss of the value is 1 347.0×106 yuan.