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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Aspects of internet security - identity management and online child protection

Durbin, Chris January 2010 (has links)
This thesis examines four main subjects; consumer federated Internet Identity Management (IdM), text analysis to detect grooming in Internet chat, a system for using steganographed emoticons as ‘digital fingerprints' in instant messaging and a systems analysis of online child protection. The Internet was never designed to support an identity framework. The current username / password model does not scale well and with an ever increasing number of sites and services users are suffering from password fatigue and using insecure practises such as using the same password across websites. In addition users are supplying personal information to vast number of sites and services with little, if any control over how that information is used. A new identity metasystem promises to bring federated identity, which has found success in the enterprise to the consumer, placing the user in control and limiting the disclosure of personal information. This thesis argues though technical feasible no business model exists to support consumer IdM and without a major change in Internet culture such as a breakdown in trust and security a new identity metasystem will not be realised. Is it possible to detect grooming or potential grooming from a statistical examination of Internet chat messages? Using techniques from speaker verification can grooming relationships be detected? Can this approach improve on the leading text analysis technique – Bayesian trigram analysis? Using a novel feature extraction technique and Gaussian Mixture Models (GMM) to detect potential grooming proved to be unreliable. Even with the benefit of extensive tuning the author doubts the technique would match or improve upon Bayesian analysis. Around 80% of child grooming is blatant with the groomer disguising neither their age nor sexual intent. Experiments conducted with Bayesian trigram analysis suggest this could be reliably detected, detecting the subtle, devious remaining 20% is considerably harder and reliable detection is questionable especially in systems using teenagers (the most at risk group). Observations of the MSN Messenger service and protocol lead the author to discover a method by which to leave digitally verifiable files on the computer of anyone who chats with a child by exploiting the custom emoticon feature. By employing techniques from steganography these custom emoticons can be made to appear innocuous. Finding and removing custom emoticons is a non-trivial matter and they cannot be easily spoofed. Identification is performed by examining the emoticon (file) hashes. If an emoticon is recovered e.g. in the course of an investigation it can be hashed and the hashed compared against a database of registered users and used to support non-repudiation and confirm if an individual has indeed been chatting with a child. Online child protection has been described as a classic systems problem. It covers a broad range of complex, and sometimes difficult to research issues including technology, sociology, psychology and law, and affects directly or indirectly the majority of the UK population. Yet despite this the problem and the challenges are poorly understood, thanks in no small part to mawkish attitudes and alarmist media coverage. Here the problem is examined holistically; how children use technology, what the risks are, and how they can best be protected – based not on idealism, but on the known behaviours of children. The overall protection message is often confused and unrealistic, leaving parents and children ill prepared to protect themselves. Technology does have a place in protecting children, but this is secondary to a strong and understanding parent/child relationship and education, both of the child and parent.
32

The impact of three dimensional digital modelling media on the modes of communication used by industrial designers

Warburton, Nina Christine January 2001 (has links)
"An investigation into the impact of 3D digital modelling media on industrial designers' internal and external modes of communication. " Effective communication in product design facilitates effective decision-making, which in turn is essential to a successful design process. The medium of communication is therefore likely to influence the decision making process, making the appropriate selection of media key to the progress of a project. Based on this premise, this study investigates the impact that 3D digital media is having on designers' internal and external modes of communication, in association with other media tools and techniques which are used. Analysis of a range of commercial product design case studies has enabled the creation of a tool assisting both the practice of industrial designers or the teaching of the use of 3D digital media to industrial design students. The tool helps designers appreciate the tactical application of digital technologies, to establish how, when and why digital media might be employed as a communication tool within the design process. Action Research methodologies were drawn on to develop a research framework for the study. This comprised three core elements: reflective practice, reflection on practice, and reflection on reflective practice. The data derived from these supported the methods used for case study compilation and cross-case analysis. The tool for practice takes the form of a heuristic map, intended to help the industrial designer understand the appropriate use, and integration of, traditional and digital media throughout the design process. Central to this understanding is the premise that it is just as important to design practice to consider 3D digital media as a tool for communication, as well as for design. The study seeks to build a bridge between theory and practice, through the amalgamation of practitioner based research and qualitative observational research methods. Publication of the findings via a CD & website contribute to the accessibility of the process and findings of the research investigation.
33

Design of computer for field problems in electron beam devices

Dinnis, A. R. January 1963 (has links)
No description available.
34

Task formulation in usability testing

AlShamari, Majed Aadi January 2010 (has links)
Usability testing is widely used for measuring a system's usability, particularly in relation to websites. It consists of a number of variables such as tasks, number of users, usability measures and other elements. Each variable can influence the usability testing results either negatively or positively. This research investigates the impact of task design upon usability testing results and further examines the role of the number of users in such testing. In addition, usability measure correlations are also explored. In order to achieve these objectives, three experiments were conducted; the first examines the proposal that task design can seriously influence usability testing results. It explores the way in which three different types of task affect these results, the types being: structured, uncertain and problem-solving. Each type of task seems to reveal different types of associated problems. Subsequently, user numbers and usability measures are also examined. In light of the first experiment's results, the second experiment's objectives investigate how a mixed set of different task types can influence the usability testing results concluding again with an examination of user numbers and usability measures. The third and final experiment validates the results of the previous two experiments by examining the influence of task order on usability testing results. The first experiment designed to investigate the influence of task type on usability testing results, involves 5 tasks all performed by 20 users for each of 3 groups. The usability testing results differ significantly. Each type of task reveals certain types of problems, and each one performs differently. In this experiment, "five users" fail to achieve what was promised i. e. the identification of 85% of usability problems. This experiment raises questions and suggests a number of recommendations, such as that tasks should be mixed in usability testing in order to offer better results: these the objectives for the 2 "d experiment. The second experiment investigates the influence of a mixed set of different task types on usability testing results. The three types of tasks above form a set of tasks to be performed by a single user or by a group of users. The participant number is increased to 30 users, who performed 10 tasks. The results show that performing a mixed set of tasks by a group of users can offer better results. In this experiment, "five users" again fail to achieve satisfactory results. This experiment suggests that task order may influence usability testing results, a question addressed in the final experiment's design. In the third experiment; therefore, the tasks are ordered differently to previous experiment. However, this is shown to have no influence on the usability testing results, although does reveal some interesting effects on users behaviour during the performance of such tasks
35

Architectures for multilingual lexical representation

Tiberius, Carola Petra Adrienne January 2001 (has links)
This thesis is an investigation of the use of inheritance networks to construct a multilingual lexicon in which information can be shared at several levels of linguistic description - morphology, phonology, syntax, etc. It aims to provide an insight into methodological and theoretical issues involved in the development of such lexicons, in particular: • The regulation of the inter- and intralanguage inheritance relations That is, how does the hierarchical structure of one language interact with the hierarchical structure between the languages? • Multilingual information sharing Which information can and should be shared in a multilingual inheritance network and how is it shared? • Development strategies How does one go about constructing a multilingual inheritance lexicon? Should the monolingual and multilingual hierarchical lexicons be developed in parallel and linked immediately upon construction or should a non-parallel development strategy be adopted, where the monolingual lexicons are first fully developed separately and only linked together at the end. This thesis explores these issues by comparing different architectures for multilingual inheritance lexicons following Evans' (1996) proposals. A parameterised approach, in which language is used as a parameter, is contrasted with a nonparameterised approach by implementing sample fragments in DATR (Evans and Gazdar, 1996). The sample fragments focus on the sharing of morphological, phonological, and morphophonological similarities and cover a small set of nouns and adjectives in Dutch, English, Danish, and Icelandic.
36

Generative web information systems

Marinos, Alexandros January 2011 (has links)
This PhD project aims to realise a new type of information system, more dynamic and less opaque to its owners, specified with structured natural language models and queried through hypermedia. To accomplish this, we focus on Semantics of Business Vocabulary and Rules (SBVR) as a modelling language, Representational State Transfer (REST) as an interface paradigm and Relational Databases as the persistence mechanism. All three of these technologies have declarative underpinnings, focusing on the ‘what’ rather than the ‘how’, which is why their combination is feasible and effective. By creating appropriate mappings to align these technologies, we create a core platform for Generative Web Information Systems (GWIS). To this end, we present an architecture that binds the three technologies together and adds the concept of a Meta-Process, a way for users to perform process-like workflows without the system having explicit processes defined. The resulting system can gracefully handle unforeseen requests its users may make. To make the Meta-Process feasible, we have created RETRO, a RESTful Transaction Model that allows users to perform more than one action with guarantees of atomicity over the Web. We also describe a service composition framework for Generative Web Information Systems which combines the strengths of the Web with the descriptive capabilities of SBVR to create a Web of Models in which GWIS are native. To validate the conceptual architecture that has been constructed, we have implemented SBVR with Sails, a prototype Generative Web Information System that serves both as a proof of concept and as a basis for future work and exploration of the concept. This model-driven and declarative approach makes semantics and policy integral to the operation of the information system and therefore the individual information system becomes a self-documenting native citizen of the digital ecosystem and the World Wide Web.
37

A Framework for Mobility.andTemporal Dimensions of Grid Systems

Aldabbas, Omar S. January 2008 (has links)
With advances in communication technology and the Internet, grid computing offers a new paradigm for distributed computing. It emerged as a mechanism for allowing a collection of connected computer systems to form a large-scale data and computing network. It promotes the sharing of distributed resources that may be heterogeneous in nature, so as to enable different application domains including science, industry, engineering, finance and even government to solve large-scale computing problems. This brings many challenges to grid resource brokering such as acting fast enough to meet the needs of new application domains. This research has therefore developed a grid resource broker that insulates users from the complexities of grids. In order to do this it executes their jobs by migrating application software, jobs and data from one site (node) to another depending on policies. It also enables advance reservation and fault tolerance. The grid resource broker combines both user-centric and systemcentric to achieve certain performance goals such as the minimisation of execution time, the optimal use of resources and minimising of the number of rejected jobs and the maximisation of resource utilisation and reliability. To request resources from the grid environment and achieve a good level of resource management and brokering within a grid environment requires languages that can specify the required resources and describe how to run jobs on them. These requests are made by users submitting jobs to the resource broker, from the resource broker to the resources, and between the resources themselves.
38

Evolving intelligent systems for ubiquitous computing technologies

Perez, Javier Andreu January 2012 (has links)
Ubiquitous Computing (UC) is a new paradigm of research aiming at creating new autonomous systems that involve humans in practical real-life situations and applications. Human behaviour follows a stochastic process and raises a high level of uncertainty. In this context, Evolving Intelligent Systems (EIS) form a new machine learning · concept for developing adaptive algorithms that work on-line and are therefore reliable in real -time applications, with a very low complexity. Their adaptation properties make this type of algorithms very suitable to address the problems of stochastic behaviours and high uncertainty. In this thesis, the theory behind EIS is explained in detail, including fuzzy rule-based inference and densitybased models. In addition, key contributions that ease their application to UC systems are highlighted. Two types of evolving classifiers, eClassO and eClassl, are proposed as well as their simplified version called Simpl_eClass. Feature processing and novel dimensionally reduction methods are proposed when necessary. The purpose is this way to address the design and computational challenges of four key subfields of UC, namely Human Activity Recognition, Mobile Computing, Scene Recognition and Ubiquitous Robots. The first entails the recognition of human activities by using pervasive wearable sensors. The second implies the implementation of the proposed algorithm in a mobile platform to detect novelties inside a video sequence and recover pictorial memories. The third consists in an image processing experiment for classifying entire images into categorical classes. Finally, the fourth introduces the development of an autonomous robotic leader-follower platform. The model settings for each experiment are detailed. Successful performance values and pattern recognition rates were achieved for the different challenges addressed. For example, classification rates ranged between 71% and 80% in the online human activity recognition case, 80% for the scene categorization problem, and 98% for the leader status recognition. Unsupervised recognition of novelties was also successfully evaluated through a user validation test. The experiments showed in all cases very good times of response and resource awareness. It is concluded that the use of EIS with on-line computation and fuzzy logic inference offers valuable assets to be exploited in future UC developments.
39

Instantaneous user identification for personalized interaction on shared surfaces

Schmidt, Dominik January 2012 (has links)
Interactive surfaces facilitate direct and expressive multi-touch, multi-user interaction, providing a compelling platform for co-located collaboration. Surface computing systems, however, are typically unaware of different users. Consequently, touch input from different users remains indistinguishable and anonymous. In this thesis, we contribute to the body of surface computing research by proposing novel methods for user identification, and by demonstrating how the so enabled personalization facilitates new types of interaction. If touch input is associated to users, applications can personalize individual interactions without constraining other concurrent users. Personalization allows for a wide range of interaction techniques that are not obvious to realize without user identification. For instance, personal clipboards may enable independent copy-and-paste operations on a shared surface. User identification for surface computing must be immediately available and smoothly integrated with direct-touch input in order to not impede the prevailing fluid multi-touch interaction style. Vie present three novel methods for instantaneous user identification on vision-based interactive surfaces: Id Wristbands uses bracelets that emit infrared codes to identify individual finger touches, HandsDown is based on biometrics and allows users to identify by placing their hand flat on the surface, and Phone Touch employs mobile phones in a stylus-like fashion for identified direct-touch interaction. Albeit following distinct identification strategies, either method allows users to spontaneously identify at arbitrary locations directly on an interactive surface. We use IdWristbands, HandsDown, and PhoneTouch as basis for analyzing and exploring the design space of personalized interaction. We illustrate its opportunities and benefits by introducing a wide range of novel user-aware interaction techniques. In a user study, we show that instantaneous user identification and personalization conveniently facilitate interaction techniques that are otherwise not immediately accessible or difficult to realize.
40

An integration framework for managing rich organisational process knowledge

Polyak, S. January 2000 (has links)
The problem we have addressed in this dissertation is that of designing a pragmatic framework for integrating the synthesis and management of organisational process knowledge which is based on domain-independent Al planning and plan representations. Our solution has focused on a set of framework components which provide methods, tools and representations to accomplish this task. In the framework we address a life-cycle of this knowledge which begins with a methodological approach to acquiring information about the process domain. We show that this initial domain specification can be translated into a common constraint-based model of activity (based on the work of Tate, 1996) which can then be operationalized for use in an Al planner. This model of activity is ontologically underpinned and may be expressed with a flexible and extensible language based on a sorted first-order logic. Synthesised or modified processes/plans can be translated to and from the common representation in order to support knowledge sharing, visualisation and mixed-initiative interaction. This work united past and present Edinburgh research on planning and infused it with perspectives from design rationale, requirements engineering, and process knowledge sharing. The implementation has been applied to a portfolio of scenarios which include process examples from business, manufacturing, construction and military operations.

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