Network Traffic Measurements, Applications to Internet Services and Security

The Internet has become along the years a pervasive network interconnecting billions of users and is now playing the role of collector for a multitude of tasks, ranging from professional activities to personal interactions. From a technical standpoint, novel architectures, e.g., cloud-based services and content delivery networks, innovative devices, e.g., smartphones and connected wearables, and security threats, e.g., DDoS attacks, are posing new challenges in understanding network dynamics. In such complex scenario, network measurements play a central role to guide traffic management, improve network design, and evaluate application requirements. In addition, increasing importance is devoted to the quality of experience provided to final users, which requires thorough investigations on both the transport network and the design of Internet services. In this thesis, we stress the importance of users’ centrality by focusing on the traffic they exchange with the network. To do so, we design methodologies complementing passive and active measurements, as well as post-processing techniques belonging to the machine learning and statistics domains. Traffic exchanged by Internet users can be classified in three macro-groups: (i) Outbound, produced by users’ devices and pushed to the network; (ii) unsolicited, part of malicious attacks threatening users’ security; and (iii) inbound, directed to users’ devices and retrieved from remote servers. For each of the above categories, we address specific research topics consisting in the benchmarking of personal cloud storage services, the automatic identification of Internet threats, and the assessment of quality of experience in the Web domain, respectively. Results comprise several contributions in the scope of each research topic. In short, they shed light on (i) the interplay among design choices of cloud storage services, which severely impact the performance provided to end users; (ii) the feasibility of designing a general purpose classifier to detect malicious attacks, without chasing threat specificities; and (iii) the relevance of appropriate means to evaluate the perceived quality of Web pages delivery, strengthening the need of users’ feedbacks for a factual assessment

GEO-REFERENCED VIDEO RETRIEVAL: TEXT ANNOTATION AND SIMILARITY SEARCH

Ph.DDOCTOR OF PHILOSOPH

Suchbasierte automatische Bildannotation anhand geokodierter Community-Fotos

In the Web 2.0 era, platforms for sharing and collaboratively annotating images with keywords, called tags, became very popular. Tags are a powerful means for organizing and retrieving photos. However, manual tagging is time consuming. Recently, the sheer amount of user-tagged photos available on the Web encouraged researchers to explore new techniques for automatic image annotation. The idea is to annotate an unlabeled image by propagating the labels of community photos that are visually similar to it. Most recently, an ever increasing amount of community photos is also associated with location information, i.e., geotagged. In this thesis, we aim at exploiting the location context and propose an approach for automatically annotating geotagged photos. Our objective is to address the main limitations of state-of-the-art approaches in terms of the quality of the produced tags and the speed of the complete annotation process. To achieve these goals, we, first, deal with the problem of collecting images with the associated metadata from online repositories. Accordingly, we introduce a strategy for data crawling that takes advantage of location information and the social relationships among the contributors of the photos. To improve the quality of the collected user-tags, we present a method for resolving their ambiguity based on tag relatedness information. In this respect, we propose an approach for representing tags as probability distributions based on the algorithm of Laplacian score feature selection. Furthermore, we propose a new metric for calculating the distance between tag probability distributions by extending Jensen-Shannon Divergence to account for statistical fluctuations. To efficiently identify the visual neighbors, the thesis introduces two extensions to the state-of-the-art image matching algorithm, known as Speeded Up Robust Features (SURF). To speed up the matching, we present a solution for reducing the number of compared SURF descriptors based on classification techniques, while the accuracy of SURF is improved through an efficient method for iterative image matching. Furthermore, we propose a statistical model for ranking the mined annotations according to their relevance to the target image. This is achieved by combining multi-modal information in a statistical framework based on Bayes' rule. Finally, the effectiveness of each of mentioned contributions as well as the complete automatic annotation process are evaluated experimentally.Seit der Einführung von Web 2.0 steigt die Popularität von Plattformen, auf denen Bilder geteilt und durch die Gemeinschaft mit Schlagwörtern, sogenannten Tags, annotiert werden. Mit Tags lassen sich Fotos leichter organisieren und auffinden. Manuelles Taggen ist allerdings sehr zeitintensiv. Animiert von der schieren Menge an im Web zugänglichen, von Usern getaggten Fotos, erforschen Wissenschaftler derzeit neue Techniken der automatischen Bildannotation. Dahinter steht die Idee, ein noch nicht beschriftetes Bild auf der Grundlage visuell ähnlicher, bereits beschrifteter Community-Fotos zu annotieren. Unlängst wurde eine immer größere Menge an Community-Fotos mit geographischen Koordinaten versehen (geottagged). Die Arbeit macht sich diesen geographischen Kontext zunutze und präsentiert einen Ansatz zur automatischen Annotation geogetaggter Fotos. Ziel ist es, die wesentlichen Grenzen der bisher bekannten Ansätze in Hinsicht auf die Qualität der produzierten Tags und die Geschwindigkeit des gesamten Annotationsprozesses aufzuzeigen. Um dieses Ziel zu erreichen, wurden zunächst Bilder mit entsprechenden Metadaten aus den Online-Quellen gesammelt. Darauf basierend, wird eine Strategie zur Datensammlung eingeführt, die sich sowohl der geographischen Informationen als auch der sozialen Verbindungen zwischen denjenigen, die die Fotos zur Verfügung stellen, bedient. Um die Qualität der gesammelten User-Tags zu verbessern, wird eine Methode zur Auflösung ihrer Ambiguität vorgestellt, die auf der Information der Tag-Ähnlichkeiten basiert. In diesem Zusammenhang wird ein Ansatz zur Darstellung von Tags als Wahrscheinlichkeitsverteilungen vorgeschlagen, der auf den Algorithmus der sogenannten Laplacian Score (LS) aufbaut. Des Weiteren wird eine Erweiterung der Jensen-Shannon-Divergence (JSD) vorgestellt, die statistische Fluktuationen berücksichtigt. Zur effizienten Identifikation der visuellen Nachbarn werden in der Arbeit zwei Erweiterungen des Speeded Up Robust Features (SURF)-Algorithmus vorgestellt. Zur Beschleunigung des Abgleichs wird eine Lösung auf der Basis von Klassifikationstechniken präsentiert, die die Anzahl der miteinander verglichenen SURF-Deskriptoren minimiert, während die SURF-Genauigkeit durch eine effiziente Methode des schrittweisen Bildabgleichs verbessert wird. Des Weiteren wird ein statistisches Modell basierend auf der Baye'schen Regel vorgeschlagen, um die erlangten Annotationen entsprechend ihrer Relevanz in Bezug auf das Zielbild zu ranken. Schließlich wird die Effizienz jedes einzelnen, erwähnten Beitrags experimentell evaluiert. Darüber hinaus wird die Performanz des vorgeschlagenen automatischen Annotationsansatzes durch umfassende experimentelle Studien als Ganzes demonstriert

A contextual analysis of compound nouns in Shona lexicography

Philosophiae Doctor - PhDThis research is in the area of lexicography and investigates the relationship between Shona terminology development and the culture of the language community for which the terminology is intended. It is a contextual analysis of compound nouns found in Shona terminological dictionaries. The study specifically explores how lexicographers together with health, music, language and literature specialists make use of their knowledge about Shona cultural contexts in the creation of compound nouns. Thus, this research foregrounds Shona socio-cultural contexts and meaning generation in terminology development. This study employs a quadruple conceptual framework. The four components of the framework that are utilised are the Traditional Descriptive Approach (TDA), Cognitive Approach (CG), Systemic Functional Approach (SFL), and Semiotic Remediation (SRM). TDA is used in the linguistic categorisation of Shona compound nouns. In addition, it provides the metalanguage with which to describe the constituent parts of Shona compound nouns. As TDA is mainly confined to the linguistic dimension, this research employs CG, SFL, and SRM to explore the cultural and socio-cognitive dimensions of terminology development.South Afric

Inter-subjectivity and intra-communality in Ciaran Carson’s Poetic Translations

This thesis presents an analysis of Northern Irish poet, Ciaran Carson’s style of poetic translation in four volumes published between 1998 and 2012: The Alexandrine Plan (1998), The Inferno of Dante Alighieri (2002), The Táin (2007), and In the Light of (2012). The thesis discusses the implementation of transitional structures for all-inclusive self-governance in Northern Ireland in 1998, the Good Friday Agreement, as the central critical context of Carson’s translational poetics. Three main areas of the Good Friday Agreement (dialogue, identity and commemoration) are discussed, both in how they have worked in cross-communal reconciliation of differences and conflict, and in how they are manifested in the practice of Carson’s translations. The critical framework for analysis consists in a sociological approach to dialogue on an inter-subjective, intra-cultural level; theories of poetic translation; and conceptual approaches to civic integration. Jürgen Habermas’s model for self-regulative dialogic practice provides a critical analysis through which to comprehend Carson’s inter-subjective approach to producing a type of translational equivalence. Carson’s ‘close’ equivalence to poetic form frames the inter-subjective exchange between translator and original poet in his commissioned versions of lyric sonnet forms and epic types of verse. His mainly ‘loose’ semantic selection of culturally symbolic signifiers and subjective poetic expression reveals his response to the originals’ contexts and styles and his way of commenting obliquely on his own cultural context. Carson demonstrates significantly different uses of form in the lyric sonnet forms published in 1998 and 2012. While authoritative form, structure and scheme either trap or distance his translated-subjects in the 1998 volume, the unstructured prose Carson selects to produce a new poetic form in the 2012 volume facilitates informal expression through unidentifiable voices and weak rhyme. Carson’s handling of lexis and syntax in the two epic types of verse demonstrate his shift from emotional evocations of communal desire and frustration to grammatical and phrasal constructions that enfold communicative acts and articulate equivalence between cultures. The exclusive and collective focus on the translation volumes presents a specific mode of analogy for individual and collective experiences of being moved into a new formal space and learning the way its language works to profitable cooperative ends

Green infrastructure

The published proceedings of the conference "Green Infrastructure: from global to local" comprises selected abstracts in English and Russian. The conference is held at the Marble Palace, St. Petersburg, Russia, and in SLU, Uppsala, Sweden on the 11–15 June 2012, and is an initiative supported by Saint-Petersburg Administration, Swedish University of Agricultural Sciences, Saint-Petersburg State Forest Technical University, FORMAS (Sweden), Baltic Institute (Sweden), and the European Federation of Landscape Architects. The abstracts came through the double blind peer reviewed process organized by the Conference Scientific Committee (Dr. Shelley Egoz (NZ), Dr. Maria Ignatieva (Sweden), Dr. Per Berg (Sweden), Dr. Rolf Johansson (Sweden), Ms Tuula Eriksson (Sweden) and Dr. Diane Menzies (NZ))