3,3,5,5-Tetra­methyl-3,5-disila-4,10-dioxatetra­cyclo­[5.5.1.02,6.08,12]tridecane-9,11-dione

The title compound, C13H20O4Si2, is a siloxane-functionalized norbornane anhydride. Both five-membered heterocyclic rings of the mol­ecule have a planar structure, whereas the two five-membered aliphatic rings assume envelope conformations. Weak inter­molecular C—H⋯O hydrogen bonding is present in the crystal structure

Phase Changes in the Evolution of the IPv4 and IPv6 AS-Level Internet Topologies

In this paper we investigate the evolution of the IPv4 and IPv6 Internet topologies at the autonomous system (AS) level over a long period of time.We provide abundant empirical evidence that there is a phase transition in the growth trend of the two networks. For the IPv4 network, the phase change occurred in 2001. Before then the network's size grew exponentially, and thereafter it followed a linear growth. Changes are also observed around the same time for the maximum node degree, the average node degree and the average shortest path length. For the IPv6 network, the phase change occurred in late 2006. It is notable that the observed phase transitions in the two networks are different, for example the size of IPv6 network initially grew linearly and then shifted to an exponential growth. Our results show that following decades of rapid expansion up to the beginning of this century, the IPv4 network has now evolved into a mature, steady stage characterised by a relatively slow growth with a stable network structure; whereas the IPv6 network, after a slow startup process, has just taken off to a full speed growth. We also provide insight into the possible impact of IPv6-over-IPv4 tunneling deployment scheme on the evolution of the IPv6 network. The Internet topology generators so far are based on an inexplicit assumption that the evolution of Internet follows non-changing dynamic mechanisms. This assumption, however, is invalidated by our results.Our work reveals insights into the Internet evolution and provides inputs to future AS-Level Internet models.Comment: 12 pages, 21 figures; G. Zhang et al.,Phase changes in the evolution of the IPv4 and IPv6 AS-Level Internet topologies, Comput. Commun. (2010

Towards a GPU SDN controller

Abstract—The SDN concept of separating and centralizing the control plane from the data plane has provided more flexibility and programmability to the deployment of the networks. On the other hand, the separation of the planes has raised some scala-bility and performance questions, being that the SDN controller is the bottleneck. In this paper we present an implementation of a GPU SDN controller. The goal of this paper is to mitigate the scalability problem of the SDN controller by offloading all the packet inspection and creation to the GPU. Experimental evaluation shows that the controller is able to process 17 Million flows/s in the worst case scenario using just off-the-shelf GPU’s. I

High Resolution BPM Upgrade for the ATF Damping Ring at KEK

A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented.Comment: 3 pp. 10th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators DIPAC 2011, 16-18 May 2011. Hamburg, German