This paper deals with a type of servicing machines model, which service station has a life time of the kth Er-langian distribution and can be repaired just like a new one. The cyclic time and the inefficiency quantiti...This paper deals with a type of servicing machines model, which service station has a life time of the kth Er-langian distribution and can be repaired just like a new one. The cyclic time and the inefficiency quantities of this system in equilibrium are obtained.展开更多
In recent years, Web services and Peer-to-Peer (or simply P2P) appear as two of the hottest research topics in network computing. On the one hand, by adopting a decentralized, network-based style, P2P technologies can...In recent years, Web services and Peer-to-Peer (or simply P2P) appear as two of the hottest research topics in network computing. On the one hand, by adopting a decentralized, network-based style, P2P technologies can make P2P systems enhance overall reliability and fault-tolerance, increase autonomy, and enable ad-hoc communication and collaboration. On the other hand, Web services provides a good approach to integrate various heterogeneous systems and applications into a cooperative environment. This paper presents the techniques of combining Web services and P2P technologies into GIS to construct a new generation of GIS, which is more flexible and cooperative. As a case study, an ongoing project JGWS is introduced, which is an experimental GIS Web services platform built on JXTA. This paper also explores the schemes of building GIS Web services in a P2P environment.展开更多
Network security policy and the automated refinement of its hierarchies aims to simplify the administration of security services in complex network environments. The semantic gap between the policy hierarchies reflect...Network security policy and the automated refinement of its hierarchies aims to simplify the administration of security services in complex network environments. The semantic gap between the policy hierarchies reflects the validity of the policy hierarchies yielded by the automated policy refinement process. However, little attention has been paid to the evaluation of the compliance between the derived lower level policy and the higher level policy. We present an ontology based on Ontology Web Language （OWL） to describe the semantics of security policy and their implementation. We also propose a method of estimating the semantic similarity between a given展开更多
As a new computing mode,cloud computing can provide users with virtualized and scalable web services,which faced with serious security challenges,however.Access control is one of the most important measures to ensure ...As a new computing mode,cloud computing can provide users with virtualized and scalable web services,which faced with serious security challenges,however.Access control is one of the most important measures to ensure the security of cloud computing.But applying traditional access control model into the Cloud directly could not solve the uncertainty and vulnerability caused by the open conditions of cloud computing.In cloud computing environment,only when the security and reliability of both interaction parties are ensured,data security can be effectively guaranteed during interactions between users and the Cloud.Therefore,building a mutual trust relationship between users and cloud platform is the key to implement new kinds of access control method in cloud computing environment.Combining with Trust Management(TM),a mutual trust based access control(MTBAC) model is proposed in this paper.MTBAC model take both user's behavior trust and cloud services node's credibility into consideration.Trust relationships between users and cloud service nodes are established by mutual trust mechanism.Security problems of access control are solved by implementing MTBAC model into cloud computing environment.Simulation experiments show that MTBAC model can guarantee the interaction between users and cloud service nodes.展开更多
To improve the performance and robustness in service discovery, a self-organizing mechanism for service alliances of Service Providers (SPs) is proposed in this paper. According to the similarity of service content, a...To improve the performance and robustness in service discovery, a self-organizing mechanism for service alliances of Service Providers (SPs) is proposed in this paper. According to the similarity of service content, an SP publishes its services in a partition of SPs to construct connections between highly similar SPs. These SPs constitute a self-organized distributed environment. A self-organizing protocol is designed to ensure the correctness of the construction of the alliances. The protocol consists of four stages - initiating stage, developing stage, developed stage and degradation stage. The experimental results demonstrate that this protocol ensures the self-property. The visualization of alliance developing stages illustrates that sub-alliances are sp lit in balance and self-connected. Compared with the Random Walker algorithm, the time cost and the number of forwarded messages in alliance-based mechanism is lower in service discovery. On three typical topologies (Grid, Random-Graph, Power-Law), the success rate of service discovery is much higher, which shows that self-organized alliances are helpful to enhance the discovery performance.展开更多
A hybrid distributed virtual environment （DVE） architecture is presented by importing a peer-to-peer （P2P） idea into the traditional client/server （C/S） architecture to improve the DVE system＇s scalability. The...A hybrid distributed virtual environment （DVE） architecture is presented by importing a peer-to-peer （P2P） idea into the traditional client/server （C/S） architecture to improve the DVE system＇s scalability. The mathematical model of the overload of the center server was built and a series of simulation experiments were performed to validate the conclusions. When the client number increases to a certain value, the hybrid architecture can reduce server overload with some special clients （temp servers） selected with a certain heuristic strategy. With this architecture, the DVE system can support more system clients with the same server hardware than the C/S architecture can. The server overload ＂pulse＂ phenomena causing by the exiting of the temp server can be resolved by adopting a more optimized temp server selecting strategy and by reducing the child client capability of the temp server. By combining the advantages of the C/S architecture and the P2P architecture, the hybrid DVE architecture can effectively improve the scalability of the DVE system. This is validated by theoretical analysis and simulation experiments.展开更多
This paper discussed the differences of context-aware service between the cloud computing environment and the traditional service system.Given the above differences,the paper subsequently analyzed the changes of conte...This paper discussed the differences of context-aware service between the cloud computing environment and the traditional service system.Given the above differences,the paper subsequently analyzed the changes of context-aware service during preparation,organization and delivery,as well as the resulting changes in service acceptance of consumers.Because of these changes,the context-aware service modes in the cloud computing environment change are intelligent,immersive,highly interactive,and real-time.According to active and responded service,and authorization and non-authorized service,the paper drew a case diagram of context-aware service in Unified Modeling Language(UML) and established four categories of context-aware service modes.展开更多
Along with the rapid development of communications,the Internet,and smart terminals,mobile Internet has become a hot topic with both opportunities and challenges.In this article,a new perspective on edge content deliv...Along with the rapid development of communications,the Internet,and smart terminals,mobile Internet has become a hot topic with both opportunities and challenges.In this article,a new perspective on edge content delivery service for mobile Internet is described,based on cooperating terminals.A mobile cloud architecture named Cloudlet Aided Cooperative Terminals Service Environment(CACTSE) is proposed as an edge network service environment.The Service Manager(SM),a cloudlet like module,is introduced into the local service domain in order to manage the in-domain terminals and help coordinate the content delivery requests for better bandwidth efficiency as well as user experience.The reference model is presented in this article with architecture and mechanism design.Moreover,the research progress and potential technology trends of CACTSE are analysed based on the related R&D directions.展开更多
Poverty reduction and environmental protection are two global tasks for sustainable development.The study perspective has changed over time,from narrowly focusing on poverty reduction to comprehensively strengthening ...Poverty reduction and environmental protection are two global tasks for sustainable development.The study perspective has changed over time,from narrowly focusing on poverty reduction to comprehensively strengthening human-welfare.We reviewed key references targeting the theoretical content and practical approach relying on poverty,environment protection and ecosystem services.We discussed the contradicting views on the relationship of poverty and environmental degradation,and then illustrated the study progress of a cutting-age topic-ecosystem services which pave a way to address poverty reduction and environmental protection together.At last,we investigated essential factors that affect the development and environmental protection.Considering the evolution of the concept of poverty,we found that the environment has occupied an increasing proportion in the cognizance of poverty.The relationship between poverty and environmental degradation is regional uniqueness.In practical aspect,projects based on the management and valuation assessment of ecosystem services draw researchers′attention all over the world.The appropriate scale,essential economic incentives,morality,law and social equality are key factors affecting individuals′decisions which directly relate to the sustainable development.展开更多
文摘This paper deals with a type of servicing machines model, which service station has a life time of the kth Er-langian distribution and can be repaired just like a new one. The cyclic time and the inefficiency quantities of this system in equilibrium are obtained.
文摘In recent years, Web services and Peer-to-Peer (or simply P2P) appear as two of the hottest research topics in network computing. On the one hand, by adopting a decentralized, network-based style, P2P technologies can make P2P systems enhance overall reliability and fault-tolerance, increase autonomy, and enable ad-hoc communication and collaboration. On the other hand, Web services provides a good approach to integrate various heterogeneous systems and applications into a cooperative environment. This paper presents the techniques of combining Web services and P2P technologies into GIS to construct a new generation of GIS, which is more flexible and cooperative. As a case study, an ongoing project JGWS is introduced, which is an experimental GIS Web services platform built on JXTA. This paper also explores the schemes of building GIS Web services in a P2P environment.
基金the National Natural Science Foundation of China
文摘Network security policy and the automated refinement of its hierarchies aims to simplify the administration of security services in complex network environments. The semantic gap between the policy hierarchies reflects the validity of the policy hierarchies yielded by the automated policy refinement process. However, little attention has been paid to the evaluation of the compliance between the derived lower level policy and the higher level policy. We present an ontology based on Ontology Web Language （OWL） to describe the semantics of security policy and their implementation. We also propose a method of estimating the semantic similarity between a given
基金ACKNOWLEDGEMENT This paper is supported by the Opening Project of State Key Laboratory for Novel Software Technology of Nanjing University, China （Grant No.KFKT2012B25） and National Science Foundation of China （Grant No.61303263）.
文摘As a new computing mode,cloud computing can provide users with virtualized and scalable web services,which faced with serious security challenges,however.Access control is one of the most important measures to ensure the security of cloud computing.But applying traditional access control model into the Cloud directly could not solve the uncertainty and vulnerability caused by the open conditions of cloud computing.In cloud computing environment,only when the security and reliability of both interaction parties are ensured,data security can be effectively guaranteed during interactions between users and the Cloud.Therefore,building a mutual trust relationship between users and cloud platform is the key to implement new kinds of access control method in cloud computing environment.Combining with Trust Management(TM),a mutual trust based access control(MTBAC) model is proposed in this paper.MTBAC model take both user's behavior trust and cloud services node's credibility into consideration.Trust relationships between users and cloud service nodes are established by mutual trust mechanism.Security problems of access control are solved by implementing MTBAC model into cloud computing environment.Simulation experiments show that MTBAC model can guarantee the interaction between users and cloud service nodes.
基金This paper was supported by the Natural Science Foundation of China under Grants No. 61170053, No. 61100205 the Nat- ural Science Foundation of Beijing under Grant No. 4112027 the Natural Science Foundation of Hebei under Grant No. F2009000929. The authors would like to thank the anony- mous reviewers for their helpful comments from which the preparation for this version of the paper has benefited.
文摘To improve the performance and robustness in service discovery, a self-organizing mechanism for service alliances of Service Providers (SPs) is proposed in this paper. According to the similarity of service content, an SP publishes its services in a partition of SPs to construct connections between highly similar SPs. These SPs constitute a self-organized distributed environment. A self-organizing protocol is designed to ensure the correctness of the construction of the alliances. The protocol consists of four stages - initiating stage, developing stage, developed stage and degradation stage. The experimental results demonstrate that this protocol ensures the self-property. The visualization of alliance developing stages illustrates that sub-alliances are sp lit in balance and self-connected. Compared with the Random Walker algorithm, the time cost and the number of forwarded messages in alliance-based mechanism is lower in service discovery. On three typical topologies (Grid, Random-Graph, Power-Law), the success rate of service discovery is much higher, which shows that self-organized alliances are helpful to enhance the discovery performance.
文摘A hybrid distributed virtual environment （DVE） architecture is presented by importing a peer-to-peer （P2P） idea into the traditional client/server （C/S） architecture to improve the DVE system＇s scalability. The mathematical model of the overload of the center server was built and a series of simulation experiments were performed to validate the conclusions. When the client number increases to a certain value, the hybrid architecture can reduce server overload with some special clients （temp servers） selected with a certain heuristic strategy. With this architecture, the DVE system can support more system clients with the same server hardware than the C/S architecture can. The server overload ＂pulse＂ phenomena causing by the exiting of the temp server can be resolved by adopting a more optimized temp server selecting strategy and by reducing the child client capability of the temp server. By combining the advantages of the C/S architecture and the P2P architecture, the hybrid DVE architecture can effectively improve the scalability of the DVE system. This is validated by theoretical analysis and simulation experiments.
基金the National Key Basic Research Program of China，the National Natural Science Foundation of China，the Ministry of Education of the People's Republic of China，the Fundamental Research Funds for the Central Universities of China
文摘This paper discussed the differences of context-aware service between the cloud computing environment and the traditional service system.Given the above differences,the paper subsequently analyzed the changes of context-aware service during preparation,organization and delivery,as well as the resulting changes in service acceptance of consumers.Because of these changes,the context-aware service modes in the cloud computing environment change are intelligent,immersive,highly interactive,and real-time.According to active and responded service,and authorization and non-authorized service,the paper drew a case diagram of context-aware service in Unified Modeling Language(UML) and established four categories of context-aware service modes.
基金supported by the "New Generation Broadband Wireless Mobile Communication Network"Key Project under Grant No. 2011ZX03005004-02the National Natural Science Foundation of China under Grants No. 60971125,No.61101119+2 种基金the Funds for Creative Research Groups of China under Grant No. 61121001the European Commission FP7 Project EVANS under Grant No. 2010-269323the Program for Changjiang Scholars and Innovative Research Team in University of China under Grant No. IRT1049
文摘Along with the rapid development of communications,the Internet,and smart terminals,mobile Internet has become a hot topic with both opportunities and challenges.In this article,a new perspective on edge content delivery service for mobile Internet is described,based on cooperating terminals.A mobile cloud architecture named Cloudlet Aided Cooperative Terminals Service Environment(CACTSE) is proposed as an edge network service environment.The Service Manager(SM),a cloudlet like module,is introduced into the local service domain in order to manage the in-domain terminals and help coordinate the content delivery requests for better bandwidth efficiency as well as user experience.The reference model is presented in this article with architecture and mechanism design.Moreover,the research progress and potential technology trends of CACTSE are analysed based on the related R&D directions.
基金Under the auspices of National Natural Science Foundation of China(No.41230745,41171156)
文摘Poverty reduction and environmental protection are two global tasks for sustainable development.The study perspective has changed over time,from narrowly focusing on poverty reduction to comprehensively strengthening human-welfare.We reviewed key references targeting the theoretical content and practical approach relying on poverty,environment protection and ecosystem services.We discussed the contradicting views on the relationship of poverty and environmental degradation,and then illustrated the study progress of a cutting-age topic-ecosystem services which pave a way to address poverty reduction and environmental protection together.At last,we investigated essential factors that affect the development and environmental protection.Considering the evolution of the concept of poverty,we found that the environment has occupied an increasing proportion in the cognizance of poverty.The relationship between poverty and environmental degradation is regional uniqueness.In practical aspect,projects based on the management and valuation assessment of ecosystem services draw researchers′attention all over the world.The appropriate scale,essential economic incentives,morality,law and social equality are key factors affecting individuals′decisions which directly relate to the sustainable development.
