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
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.
