Modelling and Design of Resilient Networks under Challenges

Communication networks, in particular the Internet, face a variety of challenges that can disrupt our daily lives resulting in the loss of human lives and significant financial costs in the worst cases. We define challenges as external events that trigger faults that eventually result in service failures. Understanding these challenges accordingly is essential for improvement of the current networks and for designing Future Internet architectures. This dissertation presents a taxonomy of challenges that can help evaluate design choices for the current and Future Internet. Graph models to analyse critical infrastructures are examined and a multilevel graph model is developed to study interdependencies between different networks. Furthermore, graph-theoretic heuristic optimisation algorithms are developed. These heuristic algorithms add links to increase the resilience of networks in the least costly manner and they are computationally less expensive than an exhaustive search algorithm. The performance of networks under random failures, targeted attacks, and correlated area-based challenges are evaluated by the challenge simulation module that we developed. The GpENI Future Internet testbed is used to conduct experiments to evaluate the performance of the heuristic algorithms developed

Novel Interference And Spectrum Aware Routing Techniques}{for Cognitive Radio Ad Hoc Networks

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2011Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2011Yüksek hızlı kablosuz ağlara artan rağbet nedeniyle, radyo spektrumu dünya üzerinde en çok kullanılan ve pahalı doğal kaynaklardan biri haline gelmiştir. Lisanslı spektrumu etkin şekilde kullanma ve paylaşmaya olanak sağlaması nedeniyle radyo spektrumundan yararlanma potansiyelini arttıran bilişsel radyo teknolojisi büyük ilgi toplamaktadır. Söz konusu potansiyelden faydalanmak üzere bilişsel radyo ağları tasarlanırken üzerinde önemle durulması gereken en önemli konulardan bir tanesi de yönlendirmedir. Çalışmamızda bilişsel radyo ağlarında kullanılmak üzere önerilen yönlendirme teknikleri hakkında bir bakış açısı sunulmakla beraber asıl olarak girişim ve spektruma dayalı özgün yönlendirme teknikleri önerilmektedir. Öncelikle, spektrum kullanım karakteristikleri ve ağdaki akışların yarattığı girişim göz önüne alınarak yönlendirme ölçütleri tasarlanmıştır. Ayrıca, bilişsel radyo ağları için otonom dağıtık uyarlanır menzil kontrol stratejisi önerilmiştir. Bu önerilere ek olarak dağıtık ve etkin bir kümeleme tabanlı yönlendirme tekniği geliştirilmiştir. Son olarak, bilişsel radyo ağları için otonom dağıtık uyarlanır menzil kontrol stratejisi ve spektrum erişebilirliği ve girişim maliyeti ölçütlerini bir arada kullanan özgün bir yönlendirme tekniği önerilmiştir. Önerilen yeni yönlendirme ölçütlerinin kullanımı nedeniyle önerilen teknik trafiği kullanılabilir spektrumun daha çok ve girişimin daha az olduğu rotalara yönlendirmektedir. NS2 benzetim ortamı kullanılarak gerçekleştirilen testler, önerilen yöntemlerin bilişsel radyo ağlarına uygunluğunu ve ağ başarımını arttırdığını göstermiştir. Ayrıca güncel bilişsel radyo teknolojisini kullanan diğer yöntemlerle karşılaştırıldığında önerilen tekniklerin hem uçtan uca veri aktarımını arttırdığı hem de uçtan uca gecikmeyi azalttığı ve başarımlarının daha yüksek olduğu gözlemlenmiştir.Radio spectrum has become one of the most heavily used and expensive natural resource around the world because of the growing demand for high-speed wireless networks. Cognitive radio has received great attention due to tremendous potential to improve the utilization of the radio spectrum by efficiently reusing and sharing the licensed spectrum. To design such mobile cognitive radio networks, routing is one of the key challenging issues to be addressed and requires deep investigation. This study gives some insights about the potential routing approaches that can be employed, and suggests novel interference and spectrum aware routing techniques for cognitive radio networks. First, the spectrum usage characteristics, and the interference created by existing flows in the network both from the primary and secondary users are taken into account to define routing metrics. Next, an autonomous distributed adaptive transmission range control scheme for cognitive radio networks is proposed. A distributed and efficient cluster based routing technique, which benefits from new metrics, is also introduced. The last proposed routing algorithm incorporates novel metrics and autonomous distributed adaptive transmission range control mechanism to provide self adaptivity. As a consequence, the proposed protocol routes traffic across paths with better spectrum availability and reduced interference via these new routing metrics. Extensive experimental evaluations are performed in the ns2 simulator to show that proposed protocols provide better adaptability to the environment and maximize throughput, minimize end-to-end delay in a number of realistic scenarios and outperforms recently proposed routing protocols developed for cognitive radio networks.DoktoraPh

Air Force Institute of Technology Research Report 2010

This report summarizes the research activities of the Air Force Institute of Technology’s Graduate School of Engineering and Management. It describes research interests and faculty expertise; lists student theses/dissertations; identifies research sponsors and contributions; and outlines the procedures for contacting the school. Included in the report are: faculty publications, conference presentations, consultations, and funded research projects. Research was conducted in the areas of Aeronautical and Astronautical Engineering, Electrical Engineering and Electro-Optics, Computer Engineering and Computer Science, Systems and Engineering Management, Operational Sciences, Mathematics, Statistics and Engineering Physic

コグニティブネットワークとヘテロジニアスネットワークの協調によるスペクトルの効率的利用に関する研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 瀬崎 薫, 東京大学教授 浅見 徹, 東京大学教授 江崎 浩, 東京大学准教授 川原 圭博, 東京大学教授 森川 博之, 東京大学教授 相田 仁University of Tokyo(東京大学

The film of tomorrow: a cultural history of videoblogging

Videoblogging is a form of cultural production that emerged in the early 2000s as a result of the increasing availability of cheap digital recording equipment, new videoediting software, video website hosting and innovative distribution networks across the internet. This thesis explores the close entanglement of culture and technology in this early and under-examined area of media production – most notably in the self-definition and development of a specific community around video practices and technologies between 2004-2009. These videobloggers’ digital works are presented as an original case study of material digital culture on the internet, which also produced a distinctive aesthetic style. The thesis traces the discourses and technological infrastructures that were developed both within and around the community of videobloggers and that created the important pre-conditions for the video artefacts they produced. Through an ethnographically-informed cultural history of the practices and technologies of videoblogging, this thesis engages with the way in which new forms of cultural and technical hybrids have emerged in an increasingly digital age. The ethnographic research is informed by histories of film and video, which contribute to the theoretical understanding and contextualisation of videoblogging – as an early digital community – which has been somewhat neglected in favour of research on mainstream online video websites, such as YouTube. The thesis also contributes to scholarly understanding of contemporary digital video practices, and explores how the history of earlier amateur and semi-professional film and video has been influential on the practices, technologies and aesthetic styles of the videobloggers. It is also shown how their aesthetic has been drawn on and amplified in network culture, mainstream media, and contemporary media and cultural production. Through a critical mapping of the socio-technical structures of videoblogging, the thesis argues that the trajectories of future media and cultural production draws heavily from the practices and aesthetics of these early hybrid networked cultural-technical communities

A Holmes and Doyle Bibliography, Volume 9: All Formats—Combined Alphabetical Listing

This bibliography is a work in progress. It attempts to update Ronald B. De Waal’s comprehensive bibliography, The Universal Sherlock Holmes, but does not claim to be exhaustive in content. New works are continually discovered and added to this bibliography. Readers and researchers are invited to suggest additional content. This volume contains all listings in all formats, arranged alphabetically by author or main entry. In other words, it combines the listings from Volume 1 (Monograph and Serial Titles), Volume 3 (Periodical Articles), and Volume 7 (Audio/Visual Materials) into a comprehensive bibliography. (There may be additional materials included in this list, e.g. duplicate items and items not yet fully edited.) As in the other volumes, coverage of this material begins around 1994, the final year covered by De Waal's bibliography, but may not yet be totally up-to-date (given the ongoing nature of this bibliography). It is hoped that other titles will be added at a later date. At present, this bibliography includes 12,594 items

A Holmes and Doyle Bibliography, Volume 6: Periodical Articles, Subject Listing, By De Waal Category

This bibliography is a work in progress. It attempts to update Ronald B. De Waal’s comprehensive bibliography, The Universal Sherlock Holmes, but does not claim to be exhaustive in content. New works are continually discovered and added to this bibliography. Readers and researchers are invited to suggest additional content. Volume 6 presents the periodical literature arranged by subject categories (as originally devised for the De Waal bibliography and slightly modified here)