33 research outputs found
Service specific management and orchestration for a content delivery network
Any non-trivial network service requires service specific orchestration to meet its carrier-grade requirements regarding resiliency, availability, etc. How the network service components are mapped on the substrate, how VNFs get reconfigured after a monitored event or how they scale, only network service/function developers know how to execute such workflows to guarantee an optimal QoS. It is therefore of paramount importance that NFV Service Platforms allow developer specified input when performing such life cycle events, instead of defining generic workflows. Within the scope of the SONATA and SGTANGO projects, a mechanism was designed that allows developers to create and execute Service and Function Specific Managers. These managers are processes, created by the developer, that define service or function specific orchestration behaviour. The SONATA Service Platform executes these managers to overwrite generic Service Platform behaviour, creating developer customised life cycle workflows. We will demonstrate the development, testing and operational execution of these managers by using a Content Delivery Network which requires specific placement and scaling behaviour
SERVICE PROVIDER AND CONTENT AWARE NETWORK PROVIDER CROSS-LAYER OPTIMISATION OF MULTIMEDIA DISTRIBUTION
ABSTRACT This work is a part of complex multi-domain eco-system specification and design aiming to deliver multimedia Quality of Services (QoS) enabled services. A cooperation framework is proposed between a high level Service Provider (SP) -managing high level services -and a Content Aware Network Provider (CANP), managing an overlay, multi-domain, transportation network. The virtual CANs are requested by a SP, negotiated with, and realised by the CANP. This cooperation, through online Service Level Agreements, creates a cross-layer optimization loop between the transport, application, and services layers. Inside the VCANs the resources for QoS assurance are assured by static and dynamic provisioning, service differentiation and media flow dynamic adaptation
The Herschel Virgo Cluster Survey - XIII. Dust in early-type galaxies
Aims. We study the dust content of a large optical input sample of 910
early-type galaxies (ETG) in the Virgo cluster, extending also to the dwarf
ETG, and examine the results in relation with those on the other cold ISM
components. Methods. We searched for far-infrared emission in all galaxies of
the input sample using the 250 micron image of the Herschel Virgo Cluster
Survey (HeViCS). This image covers a large fraction of the cluster. For the
detected ETG we measured fluxes in 5 bands from 100 to 500 micron, and
estimated the dust mass and temperature with modified black-body fits. Results.
Dust is detected above the completeness limit of 25.4 mJy at 250 micron in 46
ETG, 43 of which are in the optically complete part of the input sample. In
addition dust is present at fainter levels in another 6 ETG. We detect dust in
the 4 ETG with synchrotron emission, including M 87. Dust appears to be much
more concentrated than stars and more luminous ETG have higher dust
temperatures. Dust detection rates down to the 25.4 mJy limit are 17% for
ellipticals, about 40% for lenticulars (S0 + S0a) and around 3% for dwarf ETG.
Dust mass does not correlate clearly with stellar mass and is often much more
than that expected for a passive galaxy in a closed-box model. The
dust-to-stars mass ratio anticorrelates with galaxy luminosity, and for some
dwarf ETG reaches values as high as for dusty late-type galaxies. In the Virgo
cluster slow rotators appear more likely to contain dust than fast ones.
Comparing the dust results with those on HI from ALFALFA, there are only 8 ETG
detected both in dust and in HI in the HeViCS area; 39 have dust but only an
upper limit on HI, and 8 have HI but only an upper limit on dust. The locations
of these galaxies in the cluster are different, with the dusty ETG concentrated
in the densest regions, while the HI rich ETG are at the periphery.Comment: Accepted by Astronomy and Astrophysics; modified to reflect the
on-line forthcoming version on the A&A web sit
Multiwavelength Observations of the Low Metallicity Blue Compact Dwarf Galaxy SBS 0335-052
New infrared and millimeter observations from Keck, Palomar, ISO, and OVRO
and archival data from the NRAO VLA and IRAS are presented for the low
metallicity blue compact dwarf galaxy SBS 0335-052. Mid-infrared imaging shows
this young star-forming system is compact (0.31"; 80 pc) at 12.5 microns. The
large Br-gamma equivalent width (235 Angstroms) measured from integral field
spectroscopy is indicative of a ~5 Myr starburst. The central source appears to
be optically thin in emission, containing both a warm (~80 K) and a hot (~210
K) dust component, and the overall interstellar radiation field is quite
intense, about 10,000 times the intensity in the solar neighborhood. CO
emission is not detected, though the galaxy shows an extremely high global H I
gas-to-dust mass ratio, high even for blue compact dwarfs. Finally, the
galaxy's mid-infrared-to-optical and mid-to-near-infrared luminosity ratios are
quite high, whereas its far-infrared-to-radio and far-infrared-to-optical flux
ratios are surprisingly similar to what is seen in normal star-forming
galaxies. The relatively high bolometric infrared-to-radio ratio is more easily
understood in the context of such a young system with negligible nonthermal
radio continuum emission. These new lines of evidence may outline features
common to primordial galaxies found at high redshift.Comment: 28 pages including 6 figures; accepted for publication in the
Astronomical Journa
An adaptive system for real-time scalable video streaming with end- to-end qos control
This paper presents a real-time adaptive video streaming system based on the latest standardized video codec H.264/MPEG-4 AVC scalable extension (SVC). The system provides a full MPEG-21 media access framework over heterogeneous networks and terminals with end-to-end QoS control and multimedia adaptation based on SVC. This adaptive streaming system is composed of a server with a real-time SVC encoder, an adaptive network node, and a terminal with appropriate feedback of perceptual quality, network conditions and user preferences for adaptation support. The system facilitates a general content adaptation solution to achieve the end-to-end QoS control
Demo: closed-loop security orchestration in the telco cloud for moving target defense
This work presents a Moving Target Defense (MTD) framework for the protection of network slices and virtual resources in a telco cloud environment. The preliminary implementation provides closed-loop security management of services with proactive MTD operations to reduce the success probability of attacks, and reactive MTD operations, empowered by a tampering detection and a traffic-based anomaly detection system. MTD strategies are adaptive and optimized with deep reinforcement learning (deep-RL) for balancing costs, security, and availability goals defined in a Multi-Objective Markov Decision Process (MOMDP)
AI-enabled slice protection exploiting moving target defense in 6G networks
As commercial 5G roll-outs continue progressing, research efforts are shifting toward requirements, challenges, and critical enablers for prospective 6G networks. The introduction of Artificial Intelligence (AI) support in 5G will be further exploited, rendering AI a key enabler for providing automated network management and orchestration, while improving the network resilience against potential threat actors. Therefore, it is crucial to investigate smart security schemes in “Beyond 5G” networks. This paper presents a use case for the proactive and reactive defense of end-to-end network slices that relies on AI-based attack detection to apply Moving Target Defense (MTD) policies based on an innovative framework
A cloud-enabled small cell architecture in 5G networks for broadcast/multicast services
© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The evolution of 5G suggests that communication networks become sufficiently flexible to handle a wide variety of network services from various domains. The virtualization of small cells as envisaged by 5G, allows enhanced mobile edge computing capabilities, thus enabling network service deployment and management near the end user. This paper presents a cloud-enabled small cell architecture for 5G networks developed within the 5G-ESSENCE project. This paper also presents the conformity of the proposed architecture to the evolving 5G radio resource management architecture. Furthermore, it examines the inclusion of an edge enabler to support a variety of virtual network functions in 5G networks. Next, the improvement of specific key performance indicators in a public safety use case is evaluated. Finally, the performance of a 5G enabled evolved multimedia broadcast multicast services service is evaluated.Peer ReviewedPostprint (author's final draft
The Sigma - D relation for planetary nebulae
We present an extended analysis of the relation between radio surface
brightness and diameter -- the so-called relation for planetary
nebulae (PNe). We revise our previous derivation of the theoretical
relation for the evolution of bremsstrahlung surface brightness in order to
include the influence of the fast wind from the central star. Different
theoretical forms are derived: for the first and second
phases of evolution and for the final stage of
evolution. Also, we analyzed several different Galactic PN samples. All samples
are influenced by severe selection effects, but Malmquist bias seems to be less
influential here than in the supernova remnant (SNR) samples. We derived
empirical relations for 27 sample sets using 6 updated PN papers
from which an additional 21 new sets were extracted. Twenty four of these have
a trivial form of . However, we obtain one empirical
relation that may be useful for determining distances to PNe. This
relation is obtained by extracting a recent nearby (< 1 kpc) Galactic PN
sample.Comment: 12 pages, 3 tables, 4 figures. Accepted for publication in Astronomy
& Astrophysic