An algebraic approach to the verification of a class of Diffie-Hellman protocols

We present a framework for reasoning about secrecy in a class of Diffie-Hellman protocols. The technique, which shares a conceptual origin with the idea of a rank function, uses the notion of a message-template to determine whether a given value is generable by an intruder in a protocol model. Traditionally, the rich algebraic structure of Diffie-Hellman messages has made it difficult to reason about such protocols using formal, rather than complexity-theoretic, techniques. We describe the approach in the context of the MTI protocols, and derive conditions under which each protocol in the suite can be considered secure.     

Urban Computing and Mobile Devices

In this issue's Works in Progress department, we have 12 urban computing and mobile device entries that span a wide range of computing and social areas. The first entry examines how an urban environment could operate as a large-scale, real-time control system. One project focuses on annotating public spaces and sharing the tags with others. Two projects tie together social networking in cyberspace with local urban communities. Two projects examine computing and social interactions in physical spaces. Two entries explore how to combine synthetic and physical views of urban environments. Four entries investigate how we explore urban spaces, interact with technology in those spaces, and create shared community histories.     

Fostering trust in virtual project teams: Towards a design framework grounded in a TrustWorthiness ANtecedents (TWAN) schema

Several collaboration problems in virtual project teams that work in knowledge-intensive contexts can be attributed to a hampered process of interpersonal trust formation. Solutions to trust formation problems need to be based on an understanding of how interpersonal trust forms in face-to-face project teams as well as on insight into how this process differs in virtual teams. Synthesizing literature from various disciplines, we propose a model for the formation of interpersonal trust between project team members. Taking this model as a starting point, we analyse how virtual settings may alter or even obstruct the process of trust formation. One method to improve the formation of interpersonal trust in virtual settings is to facilitate the assessment of trustworthiness. This can be done by making information available about individual virtual project team members. Previous research in virtual project teams focussed principally on the medium by which information is spread, for example, by phone, mail, or videoconferencing. Most researchers failed to take the specific content of the information into account, although there is general agreement that personal, non-task-related information is important to foster trust. For this, we propose to use the antecedents of trustworthiness, which until now have mainly been used as a framework to measure trust, as a design framework instead. This framework of antecedents can also be used to determine which type of information is relevant to assess each other’s trustworthiness. We review existing literature on the antecedents of trustworthiness and extend the well-accepted antecedents of ‘ability’, ‘benevolence’ and ‘integrity’ with several other antecedents, such as ‘communality’ and ‘accountability’. Together, these form the TrustWorthiness ANtecedents (TWAN) schema. We describe how these antecedents can be used to determine which information is relevant for team members assessing others’ trustworthiness. In future research we will first verify this extended cognitive schema of trustworthiness (TWAN) empirically and then apply it to the design of artefacts or guidelines, such as a personal identity profile to support the assessment of trustworthiness in virtual project teams.     

An Efficient Approximate Residual Evaluation in the Adaptive Tensor Product Wavelet Method

A wide class of well-posed operator equations can be solved in optimal computational complexity by adaptive wavelet methods. A quantitative bottleneck is the approximate evaluation of the arising residuals that steer the adaptive refinements. In this paper, we consider multi-tree approximations from tensor product wavelet bases for solving linear PDE’s. In this setting, we develop a new efficient approximate residual evaluation. Other than the commonly applied method, that uses the so-called APPLY routine, our approximate residual depends affinely on the current approximation of the solution. Our findings are illustrated by numerical results that show a considerable speed-up.     

Sentiment classification of online reviews to travel destinations by supervised machine learning approaches

The rapid growth in Internet applications in tourism has lead to an enormous amount of personal reviews for travel-related information on the Web. These reviews can appear in different forms like BBS, blogs, Wiki or forum websites. More importantly, the information in these reviews is valuable to both travelers and practitioners for various understanding and planning processes. An intrinsic problem of the overwhelming information on the Internet, however, is information overloading as users are simply unable to read all the available information. Query functions in search engines like Yahoo and Google can help users find some of the reviews that they needed about specific destinations. The returned pages from these search engines are still beyond the visual capacity of humans. In this research, sentiment classification techniques were incorporated into the domain of mining reviews from travel blogs. Specifically, we compared three supervised machine learning algorithms of Naïve Bayes, SVM and the character based N-gram model for sentiment classification of the reviews on travel blogs for seven popular travel destinations in the US and Europe. Empirical findings indicated that the SVM and N-gram approaches outperformed the Naïve Bayes approach, and that when training datasets had a large number of reviews, all three approaches reached accuracies of at least 80%.     

A Belgian Transect: Field Broadcast in the expanded field of ecology

Abstract

This article sets out the notion of a Field Broadcast from the dual perspective of Rebecca Birch, one of the developers of a bespoke version of Flash Media Live Encoder and Bram Thomas Arnold, an artist who uses a case study from Sideways Festival, Belgium, 2012. Field Broadcast enables an artist to be in a field, suitably equipped, and stream live footage to an audience. It is an experiment in place, site and the notion of a field. It is a new method of making work in the space between site-specific performance and the digital realm: a way of working that enables artists to generate new artworks within the non-place of the Internet. Birch introduces the technology from a number of perspectives before it is fleshed out with evidence and experience from a live project that took place in Belgium in 2012. Sideways was a festival that traversed Belgium over four weeks and 400?km, with artists walking and generating work en route. The possibilities offered by Field Broadcast are explored in relation to the expanded field of ecology amidst Bourriaud's The Radicant (2009), Guatarri's The Three Ecologies (2005) and Morton's Ecology Without Nature (2007 Morton, Timothy. 2007. Ecology Without Nature. Cambridge, MA: Harvard University Press. [Google Scholar]).     

Optimal resource allocation in synchronized multi-tier Internet services

Modern Internet systems have evolved from simple monolithic systems to complex multi-tiered architectures. For these systems, providing good response time performance is crucial for commercial success. In practice, the response-time performance of multi-tiered systems is often degraded by severe synchronization problems, causing jobs to wait for responses from different tiers. Synchronization between different tiers is a complicating factor in the optimal control and analysis of performance. In this paper, we study a generic multi-tier model with synchronization in a queuing-theoretical setting. The system is able to share processing capacity between arriving jobs that need to be sent to other tiers and the responses that have arrived after processing from these tiers. We provide structural results on the optimal resource allocation policy and provide a full characterization of the policy in the framework of Markov decision theory. We also highlight important effects of synchronization in the model. We validate our expressions through extensive experimentations for a wide range of resource configurations.     

Complex system fault diagnosis based on a fuzzy robust wavelet support vector classifier and an adaptive Gaussian particle swarm optimization

This paper proposes a robust loss function that penalizes hybrid noise (i.e., Gaussian noise, singularity points, and larger magnitude noise) in a complex fuzzy fault-diagnosis system. A mapping relationship between fuzzy numbers and crisp real numbers that allows a fuzzy sample set to be transformed into a crisp real sample set is also presented. Furthermore, the paper proposes a novel fuzzy robust wavelet support vector classifier (FRWSVC) based on a wavelet base function and develops an adaptive Gaussian particle swarm optimization (AGPSO) algorithm to seek the optimal unknown parameter of the FRWSVC. The results of experiments that apply the hybrid diagnosis model based on the FRWSVC and the AGPSO algorithm to fault diagnosis demonstrate that it is both feasible and effective. Tests comparing the method proposed in this paper against other fuzzy support vector classifier (FSVC) machines show that it outperforms them.     

Open and Reconfigurable Hypermedia Systems: A Filter-Based Model

The need for open hypermedia systems has been well-argued by various authors. In this paper we discuss the Microcosm model for open hypermedia and show how filters have been used to extend this model both for greater efficiency and to make it totally reconfigurable. This enables users to tailor the functionality of the system to meet their own requirements, for example to select different sets of links, or to add navigation tools. The implementation of a management system for filters is described, and examples of how it has been used to extend the functionality of the model are presented, in particular the use of filters to design and implement a set of navigation tools for Microcosm. This latter case study demonstrates the power and flexibility of the filter-based model since all navigation tools for the system can be implemented as filters. The filter technology is discussed in the context of Microcosm but can be generalised to other hypermedia systems.