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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.

Learning deep representations for robotics applications

Aktaş, Ümit Ruşen January 2018 (has links)
In this thesis, two hierarchical learning representations are explored in computer vision tasks. First, a novel graph theoretic method for statistical shape analysis, called Compositional Hierarchy of Parts (CHOP), was proposed. The method utilises line-based features as its building blocks for the representation of shapes. A deep, multi-layer vocabulary is learned by recursively compressing this initial representation. The key contribution of this work is to formulate layerwise learning as a frequent sub-graph discovery problem, solved using the Minimum Description Length (MDL) principle. The experiments show that CHOP employs part shareability and data compression features, and yields state-of- the-art shape retrieval performance on 3 benchmark datasets. In the second part of the thesis, a hybrid generative-evaluative method was used to solve the dexterous grasping problem. This approach combines a learned dexterous grasp generation model with two novel evaluative models based on Convolutional Neural Networks (CNNs). The data- efficient generative method learns from a human demonstrator. The evaluative models are trained in simulation, using the grasps proposed by the generative approach and the depth images of the objects from a single view. On a real grasp dataset of 49 scenes with previously unseen objects, the proposed hybrid architecture outperforms the purely generative method, with a grasp success rate of 77.7% to 57.1%. The thesis concludes by comparing the two families of deep architectures, compositional hierarchies and DNNs, providing insights on their strengths and weaknesses.

A value and debt aware framework for evaluating compliance in software systems

Ojameruaye, Bendra January 2016 (has links)
Today's software systems need to be aligned with relevant laws and other prevailing regulations to control compliance. Compliance refers to the ability of a system to satisfy its functional and quality goals to levels that are acceptable to predefined standards, guidelines, principles, legislation or other norms within the application domain. Addressing compliance requirements at an early stage of software development is vital for successful development as it saves time, cost, resources and the effort of repairing software defects. We argue that the management of compliance and compliance requirements is ultimately an investment activity that requires value-driven decision-making. The work presented in this thesis revolves around improving decision support for compliance by making them value, risk and risk aware. Specifically, this thesis presents an economics-driven approach, which leverages on goal-oriented requirements engineering with portfolio-based thinking and technical debt analysis to enhance compliance related decisions at design-time. The approach is value driven and systematic; it leverages on influential work of portfolio thinking and technical to make the link between compliance requirements, risks, value and debt explicit to software engineers. The approach is evaluated with two case studies to illustrate its applicability and effectiveness.

Architecture-centric testing for security

Al-Azzani, Sarah January 2014 (has links)
This thesis presents a novel architecture-centric approach, which uses Implied Scenarios (IS) to detect design-vulnerabilities in the software architecture. It reviews security testing approaches, and draws on their limitations in addressing unpredictable behaviour in the face of evolution. The thesis introduces the concept of Security ISs as unanticipated (possibly malicious) behaviours that indicate potential insecurities in the architecture. The IS approach uses the architecture as the appropriate level of abstraction to tackle the complexity of testing. It provides potential for scalability to test large scale complex applications. It proposes a three-phased method for security testing: (1) Detecting design-level vulnerabilities in the architecture in an incremental manner by composing functionalities as they evolve. (2) Classifying the impact of detected ISs on the security of the architecture. (3) Using the detected ISs and their impact to guide the refinement of the architecture. The refinement is test-driven and incremental, where refinements are tested before they are committed. The thesis also presents SecArch, an extension to the IS approach to enhance its search-space to detect hidden race conditions. The thesis reports on the applications of the proposed approach and its extension to three case studies for testing the security of distributed and cloud architectures in the presence of uncertainty in the operating environment, unpredictability of interaction and possible security IS.

Trusted execution : applications and verification

Batten, Ian Gilbert January 2016 (has links)
Useful security properties arise from sealing data to specific units of code. Modern processors featuring Intel’s TXT and AMD’s SVM achieve this by a process of measured and trusted execution. Only code which has the correct measurement can access the data, and this code runs in an environment trusted from observation and interference. We discuss the history of attempts to provide security for hardware platforms, and review the literature in the field. We propose some applications which would benefit from use of trusted execution, and discuss functionality enabled by trusted execution. We present in more detail a novel variation on Diffie-Hellman key exchange which removes some reliance on random number generation. We present a modelling language with primitives for trusted execution, along with its semantics. We characterise an attacker who has access to all the capabilities of the hardware. In order to achieve automatic analysis of systems using trusted execution without attempting to search a potentially infinite state space, we define transformations that reduce the number of times the attacker needs to use trusted execution to a pre-determined bound. Given reasonable assumptions we prove the soundness of the transformation: no secrecy attacks are lost by applying it. We then describe using the StatVerif extensions to ProVerif to model the bounded invocations of trusted execution. We show the analysis of realistic systems, for which we provide case studies.

Prototyping parallel functional intermediate languages

Ben-Dyke, Andrew David January 1999 (has links)
Non-strict higher-order functional programming languages are elegant, concise, mathematically sound and contain few environment-specific features, making them obvious candidates for harnessing high-performance architectures. The validity of this approach has been established by a number of experimental compilers. However, while there have been a number of important theoretical developments in the field of parallel functional programming, implementations have been slow to materialise. The myriad design choices and demands of specific architectures lead to protracted development times. Furthermore, the resulting systems tend to be monolithic entities, and are difficult to extend and test, ultimatly discouraging experimentation. The traditional solution to this problem is the use of a rapid prototyping framework. However, as each existing systems tends to prefer one specific platform and a particular way of expressing parallelism (including implicit specification) it is difficult to envisage a general purpose framework. Fortunately, most of these systems have at least one point of commonality: the use of an intermediate form. Typically, these abstract representations explicitly identify all parallel components but without the background noise of syntactic and (potentially arbitrary) implementation details. To this end, this thesis outlines a framework for rapidly prototyping such intermediate languages. Based on the traditional three-phase compiler model, the design process is driven by the development of various semantic descriptions of the language. Executable versions of the specifications help to both debug and informally validate these models. A number of case studies, covering the spectrum of modern implementations, demonstrate the utility of the framework.

Metric learning for incorporating privileged information in prototype-based models

Fouad, Shereen January 2013 (has links)
Prototype-based classification models, and particularly Learning Vector Quantization (LVQ) frameworks with adaptive metrics, are powerful supervised classification techniques with good generalization behaviour. This thesis proposes three advanced learning methodologies, in the context of LVQ, aiming at better classification performance under various classification settings. The first contribution presents a direct and novel methodology for incorporating valuable privileged knowledge in the LVQ training phase, but not in testing. This is done by manipulating the global metric in the input space, based on distance relations revealed by the privileged information. Several experiments have been conducted that serve as illustration, and demonstrate the benefit of incorporating privileged information on the classification accuracy. Subsequently, the thesis presents a relevant extension of LVQ models, with metric learning, to the case of ordinal classification problems. Unlike in existing nominal LVQ, in ordinal LVQ the class order information is explicitly utilized during training. Competitive results have been obtained on several benchmarks, which improve upon standard LVQ as well as benchmark ordinal classifiers. Finally, a novel ordinal-based metric learning methodology is presented that is principally intended to incorporate privileged information in ordinal classification tasks. The model has been verified experimentally through a number of benchmark and real-world data sets.

The discursive constitution of software development

Cornut, Francis January 2009 (has links)
The successful development of software continues to be of central interest, both as an academic topic and in professional practice. Consequently, several software development approaches and methodologies have been developed and promoted over the past decades. However, despite the attention given to the subject and the methodical support available, software development and how it should be practiced continue to be controversial. This thesis examines how beliefs about software development come to be socially established as legitimate, and how they come to constitute software development practices in an organization. It is argued that the emergence of a dominant way of conceiving of and practicing software development is the outcome of power relations that permeate the discursive practices of organizational actors. The theoretical framework of this study is guided by Pierre Bourdieu’s theory of symbolic violence and organizational discourse theory. As a research method, ethnographic research techniques are utilized as part of a case study to gain deep insights into the standardization of software development practices. The research site is the IT division of a large financial services organization and is composed of ten units distributed across eight countries. The tumultuous development of a knowledge management programme intended to institutionalize a standard software development process across the organization’s units provides the case for this research. This thesis answers the call for studies providing detailed accounts of the sociopolitical process by which technically oriented practices are transferred and standardized within organizations. It is submitted that a discourse theoretical approach informed by Bourdieu’s thinking enables us to conceptualize this process in a more meaningful, and theoretically rigorous, manner. In providing this theoretical approach, the thesis seeks to contribute to current research on technology and innovation management, and to offer guidance on some issues concerning the management of the software development process.

ACTAS : Adaptive Composition and Trading with Agents for Services

Kloos, Reinhold January 2013 (has links)
Mainly in business domains, the vision of gaining flexible, adaptive service environments is based on the standardization and practical proliferation of (Semantic) Web Services, ontologies, and agents. The standards of Web Services and their Service-oriented Architectures (SOA) became the standard paradigm for software component integration. Dynamic changes and the permanently increasing amount of available e-services of different domains are a challenge of Service Discovery and Composition. Mediation between different approaches and expert knowledge is often necessary for the composition of services of different domains. Semantic enhancements, Autonomic Service Discovery, and the research for more holistic concepts for the classification of e-services are current attempts of overcoming this challenge, in order to reach the ultimate goal of Autonomic SOC.

Context aware Web-service monitoring

Contreas, Ricardo January 2013 (has links)
Monitoring the correct behaviour of a service-based system is a necessity and a key challenge in Service Oriented Computing. Several efforts have been directed towards the development of approaches dealing with the monitoring activity of service-based systems. However, these approaches are in general not suitable when dealing with modifications in service-based systems. Furthermore, existing monitoring approaches do not take into consideration the context of the users and how this context may affect the monitor activity. Consequently, a holistic monitor approach, capable of dealing with the dynamic nature of service-based systems and of taking into consideration the user context, would be highly desirable. In this thesis we present a monitor adaptation framework capable of dealing with changes in a service-based system and different types of users interacting with it. More specifically, the framework obtains a set of monitor rules, necessary to verify the correct behaviour of a service-based system, for a particular user. Moreover, the monitor rules verifying the behaviour of a service-based system relate to properties of the context types defined for a user. The main contributions of our work include the general characterisation of a user interacting with a service-based system and the generation of suitable monitor rules.The proposed framework can be applied to any service composition without the need of further modifications. Our work complements previous research carried on in the area of web service monitoring. More specifically, our work generates a set of suitable monitor rules - related to the user context - which are deployed in a run-time monitor component. Our framework has been tested and validated in several cases considering different scenarios.

The Agile Web Engineering (AWE) process

McDonald, Andrew Gregory January 2004 (has links)
During the late 1990s commerce and academia voiced major concerns about the problems with development processes for Web Engineering. These concerns primarily centred upon the perceived chaotic and 'ad-hoc' approach to developing Web-based applications in extremely short time-scales when compared to traditional software development. Based on personal experience, conducting a survey of current practice, and collecting supporting evidence from the literature, I proposed a set of seven criteria that need to be addressed by a successful Web engineering process: 1. Short development life-cycle times; 2. Delivery of bespoke solutions and different business models; 3. Multidisciplinary development teams; 4. Small development teams working in parallel on similar tasks; 5. Business analysis and evaluation with end-users; 6. Requirements capture and rigorous testing; 7. Maintenance (evolution) of Web-based applications. These seven criteria are discussed in detail and the relevance of each to Web engineering is justified. They are then used to provide a framework to assess the suitability of a representative sample of well-known software engineering processes for Web engineering. The software engineering processes assessed comprise: the Unified Software Development Process; Dynamic Systems Development Method; and eXtreme Programming. These seven criteria were also used to motivate the definition of the Agile Web Engineering (AWE) process. A WE is based on the principles given in the Agile Manifesto and is specifically designed to address the major issues in Web Engineering, listed above. A number of other processes for Web Engineering have been proposed and a sample of these is systematically compared against the criteria given above. The Web engineering processes assessed are: Collaborative Web Development; Crystal Orange Web; Extensions to the Rational Unified Process; and Web OPEN. In order to assess the practical application of A WE, two commercial pilot projects were carried out in a Fortune 500 financial service sector company. The first commercial pilot of A WE increased end-user task completion on a retail Internet banking application from 47% to 79%. The second commercial pilot of A WE used by an Intranet development team won the company's global technology prize for 'value add' for 2003. In order to assess the effect of AWE within the company three surveys were carried out: an initial survey to establish current development practice within the company and two further surveys, one after each of the pilot projects. Despite the success of both pilots, AWE was not officially adopted by the company for Webbased projects. My surveys showed that this was primarily because there are significant cultural hurdles and organisational inertia to adopting different process approaches for different types of software development activity within the company. If other large companies, similar to the one discussed in this dissertation, are to adopt AWE, or other processes specific to Web engineering, then many will have to change their corporate goal of a one size fits all process approach for all software technology projects.

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