As a novel architecture, software-defined networking (SDN) is viewed as the key technology of future networking. The core idea of SDN is to decouple the control plane and the data plane, enabling centralized, flexible, and programmable network control. Although local area networks like data center networks have benefited from SDN, it is still a problem to deploy SDN in wide area networks (WANs) or large-scale networks. Existing works show that multiple controllers are required in WANs with each covering one small SDN domain. However, the problems of SDN domain partition and controller placement should be further addressed. Therefore, we propose the spectral clustering based partition and placement algorithms, by which we can partition a large network into several small SDN domains efficiently and effectively. In our algorithms, the matrix perturbation theory and eigengap are used to discover the stability of SDN domains and decide the optimal number of SDN domains automatically. To evaluate our algorithms, we develop a new experimental framework with the Internet2 topology and other available WAN topologies. The results show the effectiveness of our algorithm for the SDN domain partition and controller placement problems.
Rapid Prototyping (RP) technology makes it possible for manufactories or Institutes conceiving the product directly from its CAD models without any tooling or human interference. This study explored the modeling process of toy aircraft based on Pro/Engineering through a component drawing, introduced the basic setups of Fused Deposition Modeling (FDM) process by using a rapid prototyping machine. Summarized the advantages and shortages of FDM,point out that the method using CAD&RP technology may be useful in designing a new product , it promising development in making of complex component or mould, and the need of colorful materials used in RP.
In order to study the fume suppressive effect of SBS and nano calcium carbonate, this paper studied the fume suppression laws of SBS and nano calcium carbonate, and carried out ratio test of SBS and nano calcium carbonate, and got the conclusions that: With the increasing adding level of SBS and nano calcium carbonate, the asphalt fume productive rate will reduce gradually and will reach a condition of stability. The adding level of 4% of SBS is a turning point. When less than 4%, the asphalt fume production rate decreased rapidly; and more than 4%, the asphalt fume production rate decreased slowly; when adding nano calcium carbonate at the level of 5%, the asphalt fume won’t decrease. The best ratio of SBS and nano calcium carbonate is 6% of SBS and 6% of nano calcium carbonate, with which asphalt fume reductive rate was up to 30%.
Semi-physical simulation technology and virtual reality technology in real-time three-dimensional dynamic simulation of remote operated vehicle, and a set of real ROV control system are utilized to design a ROV Training Simulator. This ROV Training Simulator can not only be used to train ROV operators, reduce the times of sea trial,but also can verify the function and performance of real ROV control system.
Based on the instance of collection the data of complex surface impeller and reconstruction the three-dimensional model, it describes the concepts and basic principles of Reverse Engineering, and discusses the entire process in detail, which are from the data of impeller collected, the impeller three-dimensional model re-Construction, fixture design to NC simulation machining. Solved the design and manufacturing problems of complex surface parts, which can not be solved by the conventional methods.
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