Pre-Congestion Notification (PCN) Architecture

This document describes a general architecture for flow admission and termination based on pre-congestion information in order to protect the quality of service of established, inelastic flows within a single Diffserv domain.\u

Requirements for Signaling of Pre-Congestion Information in a Diffserv Domain

Pre-Congestion Notification (PCN) is a means for protecting quality of service for inelastic traffic admitted to a Diffserv domain. The overall PCN architecture is described in RFC 5559. This memo describes the requirements for the signaling applied within the PCN- domain: (1) PCN-feedback-information is carried from the PCN-egress-node to the Decision Point; (2) the Decision Point may ask the PCN-ingress-node to measure, and report back, the rate of sent PCN-traffic between that PCN-ingress-node and PCN-egress-node. The Decision Point may be either collocated with the PCN-ingress-node or a centralized node (in the first case, (2) is not required). The signaling requirements pertain in particular to two edge behaviors, Controlled Load (CL) and Single Marking (SM)

Pre-Congestion Notification (PCN) Boundary-Node Behavior for the Single Marking (SM) Mode of Operation

Pre-Congestion Notification (PCN) is a means for protecting the quality of service for inelastic traffic admitted to a Diffserv domain. The overall PCN architecture is described in RFC 5559. This memo is one of a series describing possible boundary-node behaviors for a PCN-domain. The behavior described here is that for a form of measurement-based load control using two PCN marking states: not-marked and excess-traffic-marked. This behavior is known informally as the Single Marking (SM) PCN-boundary-node behavior

Overview of Pre-Congestion Notification Encoding

The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic flows within a Diffserv domain. On every link in the PCN-domain, the overall rate of PCN-traffic is metered, and PCN-packets are appropriately marked when certain configured rates are exceeded. Egress nodes provide decision points with information about the PCN-marks of PCN-packets that allows them to take decisions about whether to admit or block a new flow request, and to terminate some already admitted flows during serious pre-congestion. The PCN working group explored a number of approaches for encoding this pre-congestion information into the IP header. This document provides details of those approaches along with an explanation of the constraints that apply to any solution

Insulator-to-metal transition in Kondo insulators under strong magnetic field

Magnetization curve and changes of the single-particle excitation spectra by magnetic field are calculated for the periodic Anderson model at half-filling in infinite spatial dimension by using the exact diagonalization method. It is found that the field-induced insulator-to-metal transition occurs at a critical field $H_c$, which is of the order of the single ion Kondo temperature. The transition is of first order, but could be of second order in the infinite system size limit. These results are compared with the experiments on the Kondo insulator YbB$_{12}$.Comment: 11 pages, REVTEX, no figures; 7 figures available on request; To appear in Phys. Rev. B, Mar.15, 199

Calculation of Optical Conductivity of YbB12_{12} using Realistic Tight-Binding Model

Based on the previously reported tight-binding model fitted to the LDA+U band calculation, optical conductivity of the prototypical Kondo insulator YbB$_{12}$ is calculated theoretically. Many-body effects are taken into account by the self-consistent second order perturbation theory. The gross shape of the optical conductivity observed in experiments are well described by the present calculation, including their temperature-dependences.Comment: 6 pages, 7 figures, use jpsj2.cls, to appear in J. Phys. Soc. Jpn. Vol.73, No.10 (2004

Large, high quality single-crystals of the new Topological Kondo Insulator, SmB6

SmB6 has recently been predicted to be a Topological Kondo Insulator, the first strongly correlated heavy fermion material to exhibit topological surface states. High quality crystals are necessary to investigate the topological properties of this material. Single crystal growth of the rare earth hexaboride, SmB6, has been carried out by the floating zone technique using a high power xenon arc lamp image furnace. Large, high quality single-crystals are obtained by this technique. The crystals produced by the floating zone technique are free of contamination from flux materials and have been characterised by resistivity and magnetisation measurements. These crystals are ideally suited for the investigation of both the surface and bulk properties of SmB6

Destruction of the Mott Insulating Ground State of Ca_2RuO_4 by a Structural Transition

We report a first-order phase transition at T_M=357 K in single crystal Ca_2RuO_4, an isomorph to the superconductor Sr_2RuO_4. The discontinuous decrease in electrical resistivity signals the near destruction of the Mott insulating phase and is triggered by a structural transition from the low temperature orthorhombic to a high temperature tetragonal phase. The magnetic susceptibility, which is temperature dependent but not Curie-like decreases abruptly at TM and becomes less temperature dependent. Unlike most insulator to metal transitions, the system is not magnetically ordered in either phase, though the Mott insulator phase is antiferromagnetic below T_N=110 K.Comment: Accepted for publication in Phys. Rev. B (Rapid Communications

An Information-Centric Communication Infrastructure for Real-Time State Estimation of Active Distribution Networks

© 2010-2012 IEEE.The evolution toward emerging active distribution networks (ADNs) can be realized via a real-time state estimation (RTSE) application facilitated by the use of phasor measurement units (PMUs). A critical challenge in deploying PMU-based RTSE applications at large scale is the lack of a scalable and flexible communication infrastructure for the timely (i.e., sub-second) delivery of the high volume of synchronized and continuous synchrophasor measurements. We address this challenge by introducing a communication platform called C-DAX based on the information-centric networking (ICN) concept. With a topic-based publish-subscribe engine that decouples data producers and consumers in time and space, C-DAX enables efficient synchrophasor measurement delivery, as well as flexible and scalable (re)configuration of PMU data communication for seamless full observability of power conditions in complex and dynamic scenarios. Based on the derived set of requirements for supporting PMU-based RTSE in ADNs, we design the ICN-based C-DAX communication platform, together with a joint optimized physical network resource provisioning strategy, in order to enable the agile PMU data communications in near real-time. In this paper, C-DAX is validated via a field trial implementation deployed over a sample feeder in a real-distribution network; it is also evaluated through simulation-based experiments using a large set of real medium voltage grid topologies currently operating live in The Netherlands. This is the first work that applies emerging communication paradigms, such as ICN, to smart grids while maintaining the required hard real-time data delivery as demonstrated through field trials at national scale. As such, it aims to become a blueprint for the application of ICN-based general purpose communication platforms to ADNs

Formation Mechanism of Hybridization Gap in Kondo Insulators based on a Realistic Band Model and Application to YbB12_{12}

A new LDA+U band calculation is performed on the Kondo insulator material YbB$_{12}$ and an energy gap of about 0.001Ryd is obtained. Based on this, a simple tight-binding model with 5d$\epsilon$ and 4f $\Gamma_8$ orbitals on Yb atoms and the nearest neighbor $\sigma$-bonds between them is constructed with a good agreement to the above the LDA+U calculation near the gap. The density of states is also calculated and the shape is found to be very asymmetric with respect to the gap. A formation mechanism of the gap is clarified for the first time in a realistic situation with the orbital degeneracies in both conduction bands and the f states. This model can be a useful starting point for incorporating the strong correlation effect, and for understanding all the thermal, thermoelectric, transport and magnetic properties of YbB$_{12}$.Comment: 15 pages, 15 figures, to appear in J. Phys. Soc. Jpn. Vol. 72 No. 5 (2003