1,720,956 research outputs found
MEASUREMENT PLANE FOR INTERNET AND THE IMPLEMENTATION FOR SERVICE LEVEL AGREEMENT VERIFICATION
No full textTo take into account all the internet future evolutions network management will require many
automatic processes to allocate suitable resources according to user and operator necessities, with fast
response times and with a control managed by a centralized entity. This is the base concept of the Software
Defined Networking (SDN), where the central entity is the Orchestrator [ [1], [2], [3]]. Furthermore, one of
the fundamental task for current and future network implementation and maintenance is the control of
several network parameters, including capacity, performance, but overall user satisfaction, that currently is
meant in terms of Quality of Service (QoS). Recently another important aspect is the power consumption.
Therefore, for a correct network management, it is fundamental to take into account all these aspects. The
QoS control will require actions both in the access and in the core segment [4]. The control of the QoS can
be obtained at different levels as for an example:
a) from the user perception point of view (or Quality of the Experience, QoE) [5];
b) in terms of user bandwidth, and in this case we can distinguish different "bandwidths" according
to the OSI stack [5], in particular we can refer to the line capacity offered by the ISP (Layer 1-2,
L1-2, of the OSI stack), the bandwidth at disposal at TCP level (throughput, L4) and the
bandwidth at disposal at application level (L7);
c) passive monitoring of the traffic in some points of the network [ [6]- [7]];
d) route analysis of the packets.
The correlation among all the measurement methods, [a, b, c, d], allows us to have a good view of
the network performance and in particular to define problems and anomalies that occurs in the network. It
has to be pointed out that this is one of the aims of "quality measurement plane" of the FP7 MPLANE
project. The detection of network problems and anomalies can be a reference plane for automatic actions
in the network in order to improve the performance both for the users and for ISP (for an instance in terms
of Opex), and such a process could be also much important for Over the Top operators (OTT).
Conversely the theme of Energy Saving in telecommunication network has been treated in the
framework of the EU FP7 project TREND, where in particular several investigations were carried out on
power consumption and on the technique and algorithms to save energy, as for an example by switching
off links (physical and logic) in periods of low traffic load.
Therefore one of the most appealing topic for future networks will be the introduction of a QoSPower
management based on SDN approach and this is the subject of my Thesis. In particular for the work
of my PhD thesis I participated into two European Research projects that have allowed me to deeply study
several topics regarding energy saving in FP7 TREND project and QoS in FP7 mPlane project. On both
projects very interesting and innovative researches has been published, on which I have been part of
Facing the Reality: Validation of Energy Saving Mechanisms on a Testbed
Full text linkTwo energy saving approaches, called Fixed Upper Fixed Lower (FUFL) and Dynamic Upper Fixed Lower (DUFL), switching off idle optical Gigabit Ethernet (GbE) interfaces during low traffic periods, have been implemented on a testbed. We show on a simple network scenario that energy can be saved using off-the-shelf equipment not explicitly designed for dynamic on/off operation. No packet loss is experienced in our experiments. We indicate the
need for faster access to routers in order to perform the reconfiguration. This is particularly important for the more sophisticated energy saving approaches such as DUFL, since FUFL can be implemented locally
Unveiling Network and Service Performance Degradation in the Wild with mPlane
Full text linkpeer reviewedUnveiling network and service performance issues in complex and highly decentralized systems such as the Internet is a major challenge. Indeed, the Internet is based on decentralization and diversity. However, its distributed nature leads to operational brittleness and difficulty in identifying the root causes of performance degradation. In such a context, network measurements are a fundamental pillar to shed light and to unveil design and implementation defects. To tackle this fragmentation and visibility problem, we have recently conceived mPlane, a distributed measurement platform which runs, collects and analyses traffic measurements to study the operation and functioning of the Internet. In this paper, we show the potentiality of the mPlane approach to unveil network and service degradation issues in live, operational networks, involving both fixed-line and cellular networks. In particular, we combine active and passive measurements to troubleshoot problems in end-customer Internet access connections, or to automatically detect and diagnose anomalies in Internet-scale services (e.g., YouTube) which impact a large number of end-users
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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