The MAC protocol design for wireless sensor networks has been researched and developed for decades. SMAC protocol is a famous energy-efficient MAC protocol. Based on SMAC protocol, we find that the boundary nodes in t...The MAC protocol design for wireless sensor networks has been researched and developed for decades. SMAC protocol is a famous energy-efficient MAC protocol. Based on SMAC protocol, we find that the boundary nodes in the cluster-shaped synchronization structure bring energy consumption seriously, and provide a virtual cluster aggregation (VCA) algorithm. Because the bounder node follows multiple schedules in one cycle, it may deplete earlier and cause segmentation in wireless sensor networks. The algorithm reduces energy consumption of boundary nodes and extends the lifetime of entire sensor network by merging different virtual clusters, but increases the data transmission delay. Because the sensor nodes have the fixed duty cycle, the larger the coverage area of network is, the greater the data transmission delay increases. We propose the dynamic duty cycle (DDC) algorithm to solve this effect. When the network load and data transmission delay increase, the DDC algorithm exponentially changes the duty cycle of the node to reduce latency. The simulation results show that the performance of SMAC with the VCA and DDC algorithm obtains improvement significantly.展开更多
To save cost, more and more users choose provision resources at the granularity of virtual machines in cluster systems, especially data centres. Maintaining a consistent member view is the foundation of reliable clust...To save cost, more and more users choose provision resources at the granularity of virtual machines in cluster systems, especially data centres. Maintaining a consistent member view is the foundation of reliable cluster managements, and it also raises several challenge issues for large scale cluster systems deployed with virtual machines （which we call virtualized clusters）. In this paper, we introduce our experience in design and implementation of scalable member view management on large-scale virtual clusters. Our research contributions include three-aspects ： 1 ） we propose a scalable and reliable management infrastructure that combines a peer-to-peer structure and a hierarchy structure to maintain a consistent member view in virtual clusters; 2 ） we present a light-weighted group membership algorithm that can reach the consistent member view within a single round of message exchange; 3 ） we design and implement a scalable membership service that can provide virtual machines and maintain a consistent member view in virtual clusters. Our work is verified on Dawning 5000A, which ranked No. 10 of Top 500 super computers in November, 2008.展开更多
The most essential issue is to ensure the reliability of data transmission during wireless communication and reduce energy consumption of the network for supervising the environmental state using wireless sensor netwo...The most essential issue is to ensure the reliability of data transmission during wireless communication and reduce energy consumption of the network for supervising the environmental state using wireless sensor network(WSN).Here,a cluster-based virtual cooperative MIMO transmission scheme(CVCM) is suggested,The proposed scheme involves optimization of cooperative nodes and the modulation speed dynamically as per the distance space the cluster head and the sink node,in order to minimize the communication energy consumption of each virtual MIMO unit and the convergence node,thereby reducing the capacity consumption of the entire network.Simulation and experimental results demonstrate the effectiveness of CVCM in reducing network energy consumption,increasing the network lifetime and improving data reception performance of the base station.展开更多
This paper proposes a virtual router cluster system based on the separation of the control plane and the data plane from multiple perspectives,such as architecture,key technologies,scenarios and standardization.To som...This paper proposes a virtual router cluster system based on the separation of the control plane and the data plane from multiple perspectives,such as architecture,key technologies,scenarios and standardization.To some extent,the virtual cluster simplifies network topology and management,achieves automatic conFig.uration and saves the IP address.It is a kind of low-cost expansion method of aggregation equipment port density.展开更多
As a new type of organization form,virtual enterprise is believed to have many theoretical advantages,but these advantages have not been fully shown in practice yet.The paper intends to analyze the causes and to propo...As a new type of organization form,virtual enterprise is believed to have many theoretical advantages,but these advantages have not been fully shown in practice yet.The paper intends to analyze the causes and to propose ideas to solve the problem.Starting from the characteristics of virtual enterprise,the paper analyzes the factors hindering the practice of the virtual enterprises,evaluates the lack of existing models,and then comes to the conclusion that a unified, simplified model is more conducive to the realization of virtual enterprise according to the actual situation.Learning from the mechanism of enterprises cluster,the paper suggests a modeling framework for the new idea of virtual enterprise which is effective in operation.The main contributions of this modeling include:constitute a standardized operating platform to overcome the prime obstacle from the diversity of the partners for the practice of virtual enterprise;and set up a collaboration layer as the buffer mechanism between the partners and the database.展开更多
Virtual clustering analysis(VCA)is a reduced-order method for numerical homogenization.We formulate VCA for finite strain problems,illustrate its implementation,and provide numerical codes for free download and perusa...Virtual clustering analysis(VCA)is a reduced-order method for numerical homogenization.We formulate VCA for finite strain problems,illustrate its implementation,and provide numerical codes for free download and perusal.Comparison for four test examples shows that both VCA and Self-consistent clustering analysis(SCA)excellently approximate FFT-based direct numerical simulation(DNS)results,yet at much reduced numerical expenses.VCA is actually even faster in the online stage.展开更多
Today,lightweight virtualization technologies have been widely deployed on data centers and HPC clusters to provide highly efficient and elastic resource provisioning.Virtualization has also been extended to the I/O s...Today,lightweight virtualization technologies have been widely deployed on data centers and HPC clusters to provide highly efficient and elastic resource provisioning.Virtualization has also been extended to the I/O stack in operating system.For example,virtual switch has become the primary provider of I/O services for data movement among various light-weight virtual machines,such as Docker and Kubernetes.However,I/O stack virtualization introduces performance degradation and scalability bottleneck to the data movements of HPC computing framework,such as MPI based collective data movements and bursty asynchronous data movements.In order to study the bottleneck,we quantify and analyze the performance degradation involving with HPC data movements on virtual clusters.Then,we design a set of two-stage methods to proactively adapt the virtual network and data movement procedures.This can enhance the performance of HPC collective data movements by up to 3×.Meanwhile,a cross-layer middleware is designed to improve the performance and scalability of bursty asynchronous data movements.Our evaluation shows that it can improve the performance of real scientific application by 34.6%.展开更多
The problem of constructing global view of heterogeneous information sources for information sharing is becoming more and more important due to the availability of multiple information sources within the virtual organ...The problem of constructing global view of heterogeneous information sources for information sharing is becoming more and more important due to the availability of multiple information sources within the virtual organization. Global view is defined to provide a unified representation of the information in the different sources by analyzing concept schemas associated with them and resolving possible semantic heterogeneity. An ontology-based method for global view construction is proposed. In the method, （ 1 ） Based on the formal ontologies, the concept of semantic affinity is introduced to assess the level of semantic relationship between information classes from different information sources; （2） Information classes are classified by semantic affinity levels using clustering procedures so that their different representations can be analyzed for unification; （3） Global view is constructed starting from selected clusters by unifying representation of their elements. The application example of using the method in the joint-aerial defense organization is illustrated and the result shows that the proposed method is feasible.展开更多
Network Functions Virtualization(NFV) is an attempt to help operators more effectively manage their networks by implementing traditional network functions embedded in specialized hardware platforms in term of virtuali...Network Functions Virtualization(NFV) is an attempt to help operators more effectively manage their networks by implementing traditional network functions embedded in specialized hardware platforms in term of virtualized software instances. But, existing novel network appliances designed for NFV infrastructure are always architected on a general-purpose x86 server, which makes the performance of network functions limited by the hosted single server. To address this challenge, we propose ApplianceB ricks, a novel NFV-enable network appliance architecture that is used to explore the way of consolidating multiple physical network functions into a clustered network appliance, which is able to improve the processing capability of NFV-enabled network appliances.展开更多
Energy efficiency and sensing coverage are essential metrics for enhancing the lifetime and the utilization of wireless sensor networks. Many protocols have been developed to address these issues, among which, cluster...Energy efficiency and sensing coverage are essential metrics for enhancing the lifetime and the utilization of wireless sensor networks. Many protocols have been developed to address these issues, among which, clustering is considered a key technique in minimizing the consumed energy. However, few clustering protocols address the sensing coverage metric. This paper proposes a general framework that addresses both metrics for clustering algorithms in wireless sensor networks. The proposed framework is based on applying the principles of Virtual Field Force on each cluster within the network in order to move the sensor nodes towards proper locations that maximize the sensing coverage and minimize the transmitted energy. Two types of virtual forces are used: an attractive force that moves the nodes towards the cluster head in order to reduce the energy used for communication and a repulsive force that moves the overlapping nodes away from each other such that their sensing coverage is maximized. The performance of the proposed mechanism was evaluated by applying it to the well-known LEACH clustering algorithm. The simulation results demonstrate that the proposed mechanism improves the performance of the LEACH protocol considerably in terms of the achieved sensing coverage, and the network lifetime.展开更多
As new power systems and dual carbon policies develop,virtual power plant cluster(VPPC)provides another reliable way to promote the efficient utilization of energy and solve environmental pollution problems.To solve t...As new power systems and dual carbon policies develop,virtual power plant cluster(VPPC)provides another reliable way to promote the efficient utilization of energy and solve environmental pollution problems.To solve the coordinated optimal operation and low-carbon economic operation problem in multi-virtual power plant,a multi-virtual power plant(VPP)electricity-carbon interaction optimal scheduling model considering integrated demand response(IDR)is proposed.Firstly,a multi-VPP electricity-carbon interaction framework is established.The interaction of electric energy and carbon quotas can realize energy complementarity,reduce energy waste and promote low-carbon operation.Secondly,in order to coordinate the multiple types of energy and load in VPPC to further achieve low-carbon operation,the IDR mechanism based on the user comprehensive satisfaction(UCS)of electricity,heat as well as hydrogen is designed,which can effectively maintain the UCS in the cluster within a relatively high range.Finally,the unit output scheme is formulated to minimize the total cost of VPPC and the model is solved using theCPLEX solver.The simulation results showthat the proposed method effectively promotes the coordinated operation among multi-VPP,increases the consumption rate of renewable energy sources and the economics of VPPC and reduces carbon emissions.展开更多
Providing services on demand is a major contributing factor to drive the increasingly development of the software defined network. However, it should supply all the current popular applications before it really attain...Providing services on demand is a major contributing factor to drive the increasingly development of the software defined network. However, it should supply all the current popular applications before it really attains widespread development. Multiple Description Coding(MDC) video applications, as a popular application in the current network, should be reasonably supported in this novel network virtualization environment. In this paper, we address this issue to assign MDC video application into virtual networks with an efficient centralized algorithm(CAMDV). Since this problem is an NP-hard problem, we design an algorithm that can effectively balance the user satisfaction and network resource cost. Previous work just builds a global multicast tree for each description to connect all the destination nodes by breadth-first search strategy or shortest path tree algorithm. But those methods could not achieve an optimal balance or a high-level user satisfaction. By introducing the hierarchical clustering scheme, our algorithm decomposes the whole mapping procedure into multicast tree construction and multipath description distribution. A serial of simulation experiments show that our centralized algorithm could achieve a better performance in balancing the user satisfaction and average mapping cost in comparison with its rivals.展开更多
基金Sponsored by the Important National Science and Technology Specific Projects( Grant No. 2012ZX03004003)the National Natural Science Foundation of China( Grant No. 61171110)
文摘The MAC protocol design for wireless sensor networks has been researched and developed for decades. SMAC protocol is a famous energy-efficient MAC protocol. Based on SMAC protocol, we find that the boundary nodes in the cluster-shaped synchronization structure bring energy consumption seriously, and provide a virtual cluster aggregation (VCA) algorithm. Because the bounder node follows multiple schedules in one cycle, it may deplete earlier and cause segmentation in wireless sensor networks. The algorithm reduces energy consumption of boundary nodes and extends the lifetime of entire sensor network by merging different virtual clusters, but increases the data transmission delay. Because the sensor nodes have the fixed duty cycle, the larger the coverage area of network is, the greater the data transmission delay increases. We propose the dynamic duty cycle (DDC) algorithm to solve this effect. When the network load and data transmission delay increase, the DDC algorithm exponentially changes the duty cycle of the node to reduce latency. The simulation results show that the performance of SMAC with the VCA and DDC algorithm obtains improvement significantly.
基金Supported by the High Technology Research and Development Programme of China （No. 2006AA01 A102, 2009AA01 A129 ） and the National Natural Science Foundation of China （ No. 60703020）.
文摘To save cost, more and more users choose provision resources at the granularity of virtual machines in cluster systems, especially data centres. Maintaining a consistent member view is the foundation of reliable cluster managements, and it also raises several challenge issues for large scale cluster systems deployed with virtual machines （which we call virtualized clusters）. In this paper, we introduce our experience in design and implementation of scalable member view management on large-scale virtual clusters. Our research contributions include three-aspects ： 1 ） we propose a scalable and reliable management infrastructure that combines a peer-to-peer structure and a hierarchy structure to maintain a consistent member view in virtual clusters; 2 ） we present a light-weighted group membership algorithm that can reach the consistent member view within a single round of message exchange; 3 ） we design and implement a scalable membership service that can provide virtual machines and maintain a consistent member view in virtual clusters. Our work is verified on Dawning 5000A, which ranked No. 10 of Top 500 super computers in November, 2008.
文摘The most essential issue is to ensure the reliability of data transmission during wireless communication and reduce energy consumption of the network for supervising the environmental state using wireless sensor network(WSN).Here,a cluster-based virtual cooperative MIMO transmission scheme(CVCM) is suggested,The proposed scheme involves optimization of cooperative nodes and the modulation speed dynamically as per the distance space the cluster head and the sink node,in order to minimize the communication energy consumption of each virtual MIMO unit and the convergence node,thereby reducing the capacity consumption of the entire network.Simulation and experimental results demonstrate the effectiveness of CVCM in reducing network energy consumption,increasing the network lifetime and improving data reception performance of the base station.
基金supported by the Collaboration Research on Key Techniques of Future Network between China,Japan and Korea(2010DFB13470)~~
文摘This paper proposes a virtual router cluster system based on the separation of the control plane and the data plane from multiple perspectives,such as architecture,key technologies,scenarios and standardization.To some extent,the virtual cluster simplifies network topology and management,achieves automatic conFig.uration and saves the IP address.It is a kind of low-cost expansion method of aggregation equipment port density.
文摘As a new type of organization form,virtual enterprise is believed to have many theoretical advantages,but these advantages have not been fully shown in practice yet.The paper intends to analyze the causes and to propose ideas to solve the problem.Starting from the characteristics of virtual enterprise,the paper analyzes the factors hindering the practice of the virtual enterprises,evaluates the lack of existing models,and then comes to the conclusion that a unified, simplified model is more conducive to the realization of virtual enterprise according to the actual situation.Learning from the mechanism of enterprises cluster,the paper suggests a modeling framework for the new idea of virtual enterprise which is effective in operation.The main contributions of this modeling include:constitute a standardized operating platform to overcome the prime obstacle from the diversity of the partners for the practice of virtual enterprise;and set up a collaboration layer as the buffer mechanism between the partners and the database.
基金the National Natural Science Foundation of China(Grant Nos.11832001,11521202,and 11890681)。
文摘Virtual clustering analysis(VCA)is a reduced-order method for numerical homogenization.We formulate VCA for finite strain problems,illustrate its implementation,and provide numerical codes for free download and perusal.Comparison for four test examples shows that both VCA and Self-consistent clustering analysis(SCA)excellently approximate FFT-based direct numerical simulation(DNS)results,yet at much reduced numerical expenses.VCA is actually even faster in the online stage.
基金supported by National Key R&D Program of China under Grant No.2018YFB0204303,NSFC U1811461Guangdong Natural Science Foundation 2018B030312002the Major Program of Guangdong Basic and Applied Research 2019B030302002.
文摘Today,lightweight virtualization technologies have been widely deployed on data centers and HPC clusters to provide highly efficient and elastic resource provisioning.Virtualization has also been extended to the I/O stack in operating system.For example,virtual switch has become the primary provider of I/O services for data movement among various light-weight virtual machines,such as Docker and Kubernetes.However,I/O stack virtualization introduces performance degradation and scalability bottleneck to the data movements of HPC computing framework,such as MPI based collective data movements and bursty asynchronous data movements.In order to study the bottleneck,we quantify and analyze the performance degradation involving with HPC data movements on virtual clusters.Then,we design a set of two-stage methods to proactively adapt the virtual network and data movement procedures.This can enhance the performance of HPC collective data movements by up to 3×.Meanwhile,a cross-layer middleware is designed to improve the performance and scalability of bursty asynchronous data movements.Our evaluation shows that it can improve the performance of real scientific application by 34.6%.
基金This project was supported by the National Natural Science Foundation of China (60172012) Hunan Provincial NaturalScience Foundation of China (03JJY3110) .
文摘The problem of constructing global view of heterogeneous information sources for information sharing is becoming more and more important due to the availability of multiple information sources within the virtual organization. Global view is defined to provide a unified representation of the information in the different sources by analyzing concept schemas associated with them and resolving possible semantic heterogeneity. An ontology-based method for global view construction is proposed. In the method, （ 1 ） Based on the formal ontologies, the concept of semantic affinity is introduced to assess the level of semantic relationship between information classes from different information sources; （2） Information classes are classified by semantic affinity levels using clustering procedures so that their different representations can be analyzed for unification; （3） Global view is constructed starting from selected clusters by unifying representation of their elements. The application example of using the method in the joint-aerial defense organization is illustrated and the result shows that the proposed method is feasible.
基金supported by Program for National Basic Research Program of China (973 Program) "Reconfigurable Network Emulation Testbed for Basic Network Communication"
文摘Network Functions Virtualization(NFV) is an attempt to help operators more effectively manage their networks by implementing traditional network functions embedded in specialized hardware platforms in term of virtualized software instances. But, existing novel network appliances designed for NFV infrastructure are always architected on a general-purpose x86 server, which makes the performance of network functions limited by the hosted single server. To address this challenge, we propose ApplianceB ricks, a novel NFV-enable network appliance architecture that is used to explore the way of consolidating multiple physical network functions into a clustered network appliance, which is able to improve the processing capability of NFV-enabled network appliances.
文摘Energy efficiency and sensing coverage are essential metrics for enhancing the lifetime and the utilization of wireless sensor networks. Many protocols have been developed to address these issues, among which, clustering is considered a key technique in minimizing the consumed energy. However, few clustering protocols address the sensing coverage metric. This paper proposes a general framework that addresses both metrics for clustering algorithms in wireless sensor networks. The proposed framework is based on applying the principles of Virtual Field Force on each cluster within the network in order to move the sensor nodes towards proper locations that maximize the sensing coverage and minimize the transmitted energy. Two types of virtual forces are used: an attractive force that moves the nodes towards the cluster head in order to reduce the energy used for communication and a repulsive force that moves the overlapping nodes away from each other such that their sensing coverage is maximized. The performance of the proposed mechanism was evaluated by applying it to the well-known LEACH clustering algorithm. The simulation results demonstrate that the proposed mechanism improves the performance of the LEACH protocol considerably in terms of the achieved sensing coverage, and the network lifetime.
基金supported by the National Natural Science Foundation of China (NSFC) (Grant No.52107107).
文摘As new power systems and dual carbon policies develop,virtual power plant cluster(VPPC)provides another reliable way to promote the efficient utilization of energy and solve environmental pollution problems.To solve the coordinated optimal operation and low-carbon economic operation problem in multi-virtual power plant,a multi-virtual power plant(VPP)electricity-carbon interaction optimal scheduling model considering integrated demand response(IDR)is proposed.Firstly,a multi-VPP electricity-carbon interaction framework is established.The interaction of electric energy and carbon quotas can realize energy complementarity,reduce energy waste and promote low-carbon operation.Secondly,in order to coordinate the multiple types of energy and load in VPPC to further achieve low-carbon operation,the IDR mechanism based on the user comprehensive satisfaction(UCS)of electricity,heat as well as hydrogen is designed,which can effectively maintain the UCS in the cluster within a relatively high range.Finally,the unit output scheme is formulated to minimize the total cost of VPPC and the model is solved using theCPLEX solver.The simulation results showthat the proposed method effectively promotes the coordinated operation among multi-VPP,increases the consumption rate of renewable energy sources and the economics of VPPC and reduces carbon emissions.
基金supported by the National Basic Research Program of China (2012CB315903)the National Science and Technology Support Program (2014BAH24F01)+3 种基金the Program for Key Science and Technology Innovation Team of Zhejiang Province (2011R50010-21, 2013TD20)863 Program of China (2015AA016103)the National Natural Science Foundation of China (61379118)the Fundamental Research Funds for the Central Universities
文摘Providing services on demand is a major contributing factor to drive the increasingly development of the software defined network. However, it should supply all the current popular applications before it really attains widespread development. Multiple Description Coding(MDC) video applications, as a popular application in the current network, should be reasonably supported in this novel network virtualization environment. In this paper, we address this issue to assign MDC video application into virtual networks with an efficient centralized algorithm(CAMDV). Since this problem is an NP-hard problem, we design an algorithm that can effectively balance the user satisfaction and network resource cost. Previous work just builds a global multicast tree for each description to connect all the destination nodes by breadth-first search strategy or shortest path tree algorithm. But those methods could not achieve an optimal balance or a high-level user satisfaction. By introducing the hierarchical clustering scheme, our algorithm decomposes the whole mapping procedure into multicast tree construction and multipath description distribution. A serial of simulation experiments show that our centralized algorithm could achieve a better performance in balancing the user satisfaction and average mapping cost in comparison with its rivals.
