News and Events

Anzere: replication policy scaling for personal storage networks (Oriana Riva)


03 June, 2010

6.12, 11 am

Abstract. While managing a user's personal data (photos, contacts, music collection, etc.) with online service providers like Facebook, Google, or Yahoo offers many advantages, it is not without its drawbacks: a loss of privacy and control, lock-in, and vulnerability to provider failures due to attacks or insolvency. In this talk I will show how we built a personal storage system, called Anzere, where parts of the system use the heterogeneous ensemble of a user's devices, and parts are acquirable: the storage overlay has the option of acquiring one or more (virtual) resources, at some cost, if the benefit in data invulnerability and accessibility makes it worthwhile. Anzere makes personal data selectively available based on a set of user-specified replication policies. Compared to existing systems, it extends the expressivity of the policy language to include device-independence - referring to devices by predicate rather than name - yet still scales complex policy calculations up to very large numbers of data items. Core elements of Anzere include an overlay network, monitoring infrastructure, constraint logic solver, knowledge base, data replication, and Paxos. I will present initial results from trials of the system across personal computers, phones, and dynamically-acquired virtual machines from Amazon EC2 and PlanetLab.

Bio. Oriana Riva has been a senior researcher in the Systems Group at ETH Zurich since December 2007. She received her M.Sc. in Telecommunications Engineering from Politecnico di Milano in 2003, and her Ph.D. in Computer Science from the University of Helsinki in 2007. Her research interests are in distributed systems, with a focus on cloud computing infrastructures and mobile phone architectures. She was awarded an ETH Fellowship in 2008.

 

Coexistence, Collaboration, and Coordination Paradigms in the Presence of Mobility (Catalin Roman)


02 June, 2010

Abstract: Mobile computing is a broad field of study made possible by advances in wireless technology, device miniaturization, and innovative packaging of computing, sensing, and communication resources. This talk is intended as a personal intellectual journey spanning a decade of research activities, which have been shaped by the concern with rapid development of applications designed to operate in the fluid and dynamic settings that characterize mobile and sensor networks. The presence of mobility often leads to fundamental changes in our assumptions about the computing and communication environment and about its relation to the physical world and the user community. This, in turn, can foster a radical reassessment of one's perspective on software system design and deployment. Several paradigm shifts made manifest by considerations having to do with physical and logical mobility will be examined and illustrated by research involving formal models, algorithms, middleware, and protocols. Special emphasis will be placed on problems that entail collaboration and coordination in the mobile setting.

Bio: Gruia-Catalin Roman Harold B. and Adelaide G. Welge Professor of Computer Science Washington University in Saint Louis Gruia-Catalin Roman has an established research career with numerous published papers in a multiplicity of computer science areas including mobile computing, formal design methods, visualization, distributed systems, interactive high speed computer vision algorithms, formal languages, biomedical simulation, computer graphics, and distributed database. His current research involves the study of formal models, algorithms, design methods, and middleware for mobile computing and sensor networks. Roman was a Fulbright Scholar at the University of Pennsylvania, in Philadelphia, where he received his B.S. (1973), M.S. (1974), and Ph.D. (1976) degrees, all in computer science. He has been on the faculty of the Department of Computer Science and Engineering at Washington University in Saint Louis since 1976 and serves as department chair, a position he held for twelve years. Roman served as associate editor for ACM TOSEM, held leading positions in several international conferences and workshops, was the general chair for ICSE 2005, and is the general chair for FSE 2010. He is also a successful software engineering consultant, a founding member of the Saint Louis Information Technology Coalition, and an external advisor for the Saint Louis Science Center.

 

Kerstin Sailer: Relationships in the Workplace - Organisational Structures, Social Networks and Spatial Configuration


13 April, 2010

1pm, 6.12 MPEB

How people relate to others in the workplace can be argued to arise from organisational structures and cultures on the one hand, but also from the spatial configuration of workplaces on the other. While scholars in organisational theory and sociology routinely study relationships within organisations, the spatial contexts within which these relationships enfold are often ignored completely. Using Space Syntax as a theory and method of analysing spatial configurations, it is suggested that physical space has a major bearing on the emergence of social life.

This talk will present various datasets on the relationship between organisation and space taken from my PhD and ongoing research, but also from a continuous workplace consultancy engagement with Spacelab Architects. It will be shown how relationships between people emerge from organisational and social processes, but also how deeply they are embedded in their specific physical surroundings.

Short Bio:

Kerstin Sailer is Lecturer in Complex Buildings at the Bartlett School of Graduate Studies at UCL. Her research interests include complex buildings and workplace environments, spatial analysis and Space Syntax, organisational theory and organisational behaviour, Social Network Analysis, and evidence-based design practices.

She is also heading the research activities of the London-based architectural practice Spacelab, offering workplace consultancy services to clients, developing and implementing evidence-based design processes, and conducting research-based case studies.

Being a trained architect from Germany, she graduated from the Leibniz-University of Hannover/Germany in 2003. Her PhD at TU Dresden/Germany on the “Space-Organisation Relationship” is due for completion in April 2010.

 

On Demand Connectivity Sharing (Ioannis Psaras)


18 March, 2010

4pm, 1.02 MPEB

We will introduce the concept of "On Demand Connectivity Sharing," which we build on top of User-Provided Networks (UPNs). UPNs were recently proposed as a new connectivity paradigm, according to which home-users share their broadband Internet connection with roaming guests. We enhance this paradigm with incentives, rules and policies, based on which: (i) home-users provide on-demand connectivity only (i.e., they do not explicitly allocate a portion of their bandwidth) and (ii) guest-users utilize resources that remain unexploited from the respective home-users.

Our findings indicate the following: (i) ubiquitous Internet connectivity (in densely populated, urban areas) is already possible, since the necessary infrastructure is in place, (ii) resource sharing can take place in a seamless manner for the home-user and (iii) mobile-, guest-users can have acceptable performance for short data-transfers, such as e-mailing, surfing, map-download or photo uploads.

 

Cooperative Leader Election Algorithm for Master/Slave Mobile Ad Hoc Networks (Redouane Ali)


08 December, 2009

2pm, 6.12 MPEB

This paper proposes a novel and efficient cooperative leader election algorithm for master/slave mobile ad hoc networks. The algorithm relies on collecting and re-distributing information amongst local nodes in order to find the leader. It is based on the assumption that if this process is repeated sufficiently then the algorithm will converge towards a unique leader. It is shown that the proposed mechanism outperforms existing algorithms in terms of time complexity and response to node mobility. The algorithm was simulated for Bluetooth ad hoc networks, which, by default, rely on a master/slave architecture, however, the cooperative approach could be adapted to any network that exhibits the master/slave configuration such as clustered ad hoc networks or ZigBee-based sensor networks.

 

Cooperative Equilibrium and Reputation Models (Mohamed Ahmed)


01 December, 2009

6.12 MPEB, 2pm

The assessment and use of reputations to make decisions that may involve risk - in the form of a loss in utility - raises a number fundamental questions regarding the properties of reputation models. Amongst these is what types of equilibrium exist to support a cooperative outcome. In this talk we show how the characteristics of the interaction model shape the type of feasible equilibrium and highlight the short comings this raises for making decisions based on reputations.

 

Socia Ranking: Finding Relevant Content Using Tag-based Recommender Systems (Valentina Zanardi)


24 November, 2009

2pm, 6.12 MPEB

The rise of Web 2.0 has emphasized new issues and challenges for the research community. The amount of data produced and consumed by users has been exponentially increasing under the incentives exerted by the proliferation of information sharing communities. An enormous amount of pictures, blog entries, messages and media resources are flowing and are being shared all over the network, backed also by the growing connectivity of new generation mobile devices.

The new pervasive technologies allow everyone to access and load their contents and resources online, regardless of their location. Disseminating, disclosing and, in general, sharing data have become mainstream activities.
In this scenario, a new trend called social (or folksonomic) tagging has emerged as the most popular way to describe, categorize, search and navigate information. Folksonomies allow users to associate data with customized tags, without forcing information to be categorized in pre-existent hierarchies: users uploading resources on the web are free to label data with the unlimited vocabulary of spoken language.

However, as tags are informally defined, continually changing and ungoverned, social tagging has often been criticized for lowering, rather than increasing, the efficiency of searching. New ways of retrieving information matching users’ requests must be investigated.

Our work aims at facilitating the problem of information retrieval for Web 2.0 scenarios in which items are not categorized into hierarchies, but defined with descriptive tags, and explicit ratings are not available to understand users’ preferences: interests are implicitly inferred from bookmarked items.
By means of an extensive set of experiments using a variety of large-scale real datasets (CiteULike, MovieLens, Bibsonomy, Delicious), the proposed solution will be evaluated in terms of accuracy (how much returned data accomplish users’ interests), completeness (how much relevant data is retrieved) and scalability (how the solution can handle growing amount of content).

 

CoHabit: Fair content dissemination protocol for participatory DTNs (Afra Mashadi)


17 November, 2009

2pm, 6.12 MPEB

Thanks to advances in the computing capabilities and added functionalities of modern mobile devices, creating digital media on the move has never been so easy and popular. However, the distribution of such content still represents a challenge: the coverage/stability of 3G networks is limited, and their cost high. As a result, distributing content using Delay Tolerant Networks (DTNs) has become an attractive alternative.

Most of the DTN routing protocols proposed in the literature have been exploiting users' mobility patterns, in order to maximise the delivery probability, while minimising the overall network overhead (e.g., number of replicas in the system, messages' path length). Common to all these protocols has been the assumption that devices are willing to participate in the content distribution network; however, because of battery constraints, participation cannot be taken for granted, especially if the very same subset of devices are continuously selected as content carriers, simply because of their mobility properties. Indeed, we demonstrate that state-of-the-art DTN routing protocols distribute load in a highly unfair manner, with detrimental effects on delivery once the assumption of unconditional participation is lifted.

To overcome this problem, we propose CoHabit, a fair content dissemination protocol for participatory DTNs.  By adopting a source-based approach to routing, local estimations of the network workload can be computed and used to select routes that favour the least loaded portion of the network, thus preventing unduly load distribution. We demonstrate, by means of simulation using real large-scale mobility traces, that CoHabit achieves high delivery without compromising fairness.

 

Renzo De Nardi: Coevolutionary Modelling Of A Miniature Rotorcraft


27 October, 2009

2pm, 6.12 MPEB

 

The talk considers the problem of synthesising accurate dynamic models of a miniature rotorcraft based on minimal knowledge about the flying machine. The approach is based on the idea of building models that predict the dynamic accelerations affecting the platform, and is implemented using evolutionary programming. A co-evolutionary framework is shown to be very effective in identifying both the structure and the parameters of the nonlinear models from real flight data. The modelling method is demonstrated on a miniature quadrotor rotorcraft; the automatically obtained models are used to develop a controller capable of autonomous flight.

 

Graeme McPhillips: A Brief Introduction to Robotics


13 October, 2009

2pm, 6.12 MPEB

 

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