616 research outputs found

    (EMC)-M-3: Improving Energy Efficiency via Elastic Multi-Controller SDN in Data Center Networks

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    Energy consumed by network constitutes a significant portion of the total power budget in modern data centers. Thus, it is critical to understand the energy consumption and improve the power efficiency of data center networks (DCNs). In doing so, one straightforward and effective way is to make the size of DCNs elastic along with traffic demands, i.e., turning off unnecessary network components to reduce the energy consumption. Today, software defined networking (SDN), as one of the most promising solutions for data center management, provides a paradigm to elastically control the resources of DCNs. However, to the best of our knowledge, the features of SDN have not been fully leveraged to improve the power saving, especially for large-scale multi-controller DCNs. To address this problem, we propose (EMC)-M-3, a mechanism to improve DCN\u27s energy efficiency via the elastic multi-controller SDN. In (EMC)-M-3, the energy optimizations for both forwarding and control plane are considered by utilizing SDN\u27s fine-grained routing and dynamic control mapping. In particular, the flow network theory and the bin-packing heuristic are used to deal with the forwarding plane and control plane, respectively. Our simulation results show that E3MC can achieve more efficient power management, especially in highly structured topologies such as Fat-Tree and BCube, by saving up to 50% of network energy, at an acceptable level of computation cost

    Topological carbon materials: a new perspective

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    Carbon has numerous one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) allotropic structures. The study of carbon materials has been a major focus of material science and condensed matter physics. Previous studies have identified different classes of topological semimetallic carbon allotropes with different topological phases. In this review, we first give a brief summary of the development of carbon allotropes from 1D to 3D. Next, we discuss topological properties of carbon materials and their physical origin. Then, we consider possible expansion of the topological study of carbon materials to other light-element materials such as boron. Finally, we present future prospects in pursue of topological physics within carbon allotropes

    Research on Traffic Artery Intelligent Control System Based on Wireless Sensor Network

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    Based on the researches on controlling urban artery traffic, a hierarchical control method for traffic signals at artery multi-crossings is proposed. This control method, which uses wireless sensor networks and fuzzy control method, has two layers of WSN. The first layer is a data collecting layer which consists of terminal nodes and sink nodes. This data collecting layer is responsible for collecting and transmitting vehicle information to the second layer after data fusion at the single crossings. The fuzzy controller, nested in the sink nodes, is used to accomplish traffic light control and adjusting on-line the green ratio in all directions at crossings. The second layer is the control layer, composed of coordinator nodes in which the fuzzy controller is nested. The coordinator nodes are used to receive the traffic data detected by the first layer, the real traffic data and the forecasting traffic datas are input into the fuzzy controller. The fuzzy controller determines the signal cycles at the artery. Simulation results have shown that this method is superior to the ordinary fuzzy control, effectively reducing queue length of vehicles and traffic delays

    Utility of AD8 for Cognitive Impairment in a Chinese Physical Examination Population: A Preliminary Study

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    were subjected to AD8 scale. Individual information such as age, gender, and education was also collected. All data were analyzed by SPSS 19.0. Results. 1544 subjects were enrolled in this study with mean age 75.4 ± 10.6 years. The subjects who scored 0 to 8 of AD8 scale were 1015, 269, 120, 60, 30

    Generation of PCV2 in PK15 cells transfected with recombinant baculovirus containing a 1.1 copy of the PCV2 genome

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    Porcine circovirus associated diseases (PCVAD) caused by PCV2 are responsible for severe economic losses in the swine industry. The mechanism of PCV2 replication has not been fully elucidated yet. PCV2 may be successfully rescued by means of either an infectious DNA clone containing the full length of the viral genomic DNA, or from PCV2-infected clinical tissues in PK15 cell culture. However, viruses harvested by both methods have low titres. In this study, PCV2 was prepared with a higher titre from PK15 cells infected by recombinant baculoviruses containing 1PCV2 (one stem-loop structure) or 1.1PCV2 (two stem-loop structure) genomic DNA copy. In addition, infectious DNA clones containing two stem-loop structures in either plasmid or baculovirus backbones are capable of generating a higher virus titre than the DNA clones with only one copy of stem-loop structure
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