Chronic disorders and diseases that affect the cerebrum and the central nervous system, e.g. motor neuron disease, cerebrovascular accident, etc., incapacitate the individual and place a burden on societies and global health systems. The associated health problems of such conditions cannot be eased until further advances are made in neurology and medicine. Potentially, Computing Science can assist individuals with these types of afflictions by providing alternative methods for communication and control. The research discussed herein undertakes the design and evaluation of a collaborative Brain-Computer Interface (BCI) as an Assistive Technology (AT), referred to as a hybrid BCI (/zBCI). The research weaved together three computing topics: BCI, Eye Tracking (ET), and smart environments. A solution was devised with the intention to improve upon conventional BCIs as an AT for those that could potentially benefit from it the most. Five systems were evaluated as a smart environment control mechanism: 1) Steady State Visually Evoked Potential (SSVEP) BCI; 2) an ET-based AT; 3) an ET collaboration with a brain-neuronal computer interaction component; 4) SSVEP BCI with on-screen stimulation; and 5) a hybrid BCI. Significant contributions to knowledge were gathered from the experimentation and evaluation of healthy and brain-injured participants. The development of the ABCI enhanced the performance and usability of both BCI and ET technology. It provided accuracy of 99.84% in healthy volunteers and 99.14% in brain-injured participants. In addition, information transfer rate reached 24.41 bits/min in healthy volunteers and 15.87 bits/min in brain-injured participants. The inclusion of ET did not introduce further intrusion and offered a cost-effective supplementary modality to the BCI. This research has provided an important advance on the state of the art in brain-computer interaction; indeed, the multimodal approach provided deeper understanding o f the decision process by providing insight to behavioural interaction and neural processes in real time.

Making the use of an unfamiliar digital user interface (Ul) easy, transparent and accessible is a challenging problem, particularly when the interaction occurs without any prior experience. Where and how the user pays attention is critical for the development of an effective human-computer interaction (HCI). The role of attention is particularly important in cases of an inexperienced user, unaccustomed to receiving valuable information for the interaction. Therefore, a recurring problem during an unfamiliar transaction is ‘what to do next’, where the user fails to anticipate the following step. This problem is well illustrated in the context of transactions using Self-Service Technologies, where the next step is likely to be unidentified by an inexperienced or first-time user, and accentuated by the lack of help or human assistance. This thesis applies an interdisciplinary blend of Psychological, Animation and HCI principles relating to guiding users unfamiliar with the Ul to ease the digital interaction. A series of experiments address visuo-spatial mechanisms of guidance to orient and direct user attention during a search of target items inside a Ul. Dynamically animated virtual agent (VA) gaze and head cues were found to guide eye gaze and button presses faster than 1-image and 2- image agent cues. When these cues were animated using the principles of animation, they introduced a substantial increase in the likeability of the agent observed but also delaying the response latency. The use of the ‘exaggeration’ principle of animation was shown to provide the optimal balance between response speed and preference. Following on from the experiments, the thesis develops a formal categorisation for a user who occasionally uses UIs, the Occasional User (OU), and the specific development of a new interaction style for the OU, represented by a guideduser interface, that does not require any prior experience and only a minimum knowledge of to use it. In summary, this overall analysis of guidance mechanisms and unfamiliar HCI contexts indicates that VA visual cues influence the overt allocation of user attention and that, in combination with an ad-hoc interaction style, may be used to enhance occasional digital interactions.

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This research makes an in-depth examination and comparison of plan-driven and agile methods in software design to justify the need for a more balanced approach that combines the controlling and disciplining capabilities of the former with the flexibility of the latter. It also examines the concept of software usability and the process of gathering requirements in software engineering. It is noted that pure agile methodologies tend to ignore usability for end users, hence the attention to User-Centred Design (UrCD). Software development methods based on UrCD attempt to alleviate this neglect, but they too are not sufficiently grounded in traditional plan-driven approaches that can adequately target usability concerns, especially during the planning phase of development. Capturing usability requirements could be key to ensuring a high degree of software usability for end users. It is suggested that Usage-Centred Design (UgCD), with its focus on actual software usage rather than users per se, can satisfy this need for greater software usability through increasing the likelihood of achieving a more complete and precise capture of usability requirements. This methodology introduced by Constantine combines task modelling as its plan-driven phase for identifying users, roles and essential tasks with an agile iterative component for facilitating continuous consultation with users to also enable refinements to be made to the requirements. The focus in this study is on the requirements analysis phase of UgCD to demonstrate how it can be applied for better capturing usability requirements in terms of completeness and preciseness. The usability aspects analysed are learnability, rememberability, efficiency, reliability, and user satisfaction. Research was carried out involving a survey, interviews and a demonstration of UgCD at a higher education institution in Saudi Arabia during a revision of an e-learning software, and a further follow on survey and interview. The survey investigated existing usability requirements gathering practices, and the current methods used for the sake of ensuring and thereafter testing for usability. The interviews provided insight into these developer practices to especially ascertain how well they are able to capture usability requirements for particular aspects of usability and their awareness of these aspects. A total of 212 software developers working in higher education institutions throughout the Saudi kingdom participated in the survey, 20 of them participated further in the interviews from three different cities, and the UgCD demonstration was held at one higher education institution. The survey analysis included frequency, factor and correlational analyses, and the interviewee responses were analysed using thematic analysis. The list of usability requirements captured during the UgCD demonstration was compared to the original capture at the time of construction and to the pre-UgCD period when usability questionnaires were being used. The UgCD implementation enabled a 7.5-fold increase in completeness and 43% improvement in preciseness compared with the original capture, and a 2.5 gain in completeness and 24% improvement in preciseness compared to the requirements captured using usability questionnaires. The pre-UgCD survey results and interview findings are also presented and discussed that show a need to promote not only UgCD, but also to raise awareness of usability itself and make developers appreciate its importance. This led to developing a framework of principles for implementing UgCD, which is presented to guide developers in capturing usability requirements for enhanced software usability. However, it is noted that in line with the need to understand and promote usability, developers also need to be encouraged to consult frequently with their potential and existing users and become accustomed to holding frequent meetings with them. These changes would be necessary in order to be able to implement UgCD fully. Regardless, the potential of UgCD is established at least with respect to its capability to make developers and users focus on usability and in capturing a more complete and precise set of usability requirements that pertain to a wide range of usability aspects. Also, the post-UgCD survey with the meeting participants and interview with the leading developer give further positive indications for the success of the UgCD trial, and its potential for being used to enhance software usability.

POSIX is a standard for operating systems, with a substantial part devoted to specifying file-system operations. File-system operations exhibit complex concurrent behaviour, comprising multiple actions affecting different parts of the state: typically, multiple atomic reads followed by an atomic update. However, the standard's description of concurrent behaviour is unsatisfactory: it is fragmented; contains ambiguities; and is generally under-specified. We provide a formal concurrent specification of POSIX file systems and demonstrate scalable reasoning for clients. Our specification is based on a concurrent specification language, which uses a modern concurrent separation logic for reasoning about abstract atomic operations, and an associated refinement calculus. Our reasoning about clients highlights an important difference between reasoning about modules built over a heap, where the interference on the shared state is restricted to the operations of the module, and modules built over a file system, where the interference cannot be restricted as the file system is a public namespace. We introduce specifications conditional on context invariants used to restrict the interference, and apply our reasoning to lock files and named pipes. Program reasoning based on separation logic has been successful at verifying that programs do not crash due to illegal use of resources, such invalid memory accesses. The underlying assumption of separation logics, however, is that machines do not fail. In practice, machines can fail unpredictably for various reasons, such as power loss, corrupting resources or resulting in permanent data loss. Critical software, such as file systems and databases, employ recovery methods to mitigate these effects. We introduce an extension of the Views framework to reason about programs in the presence of such events and their associated recovery methods. We use concurrent separation logic as an instance of the framework to illustrate our reasoning, and explore programs using write-ahead logging, such a stylised ARIES recovery algorithm.

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The use of virtual appliances could provide a flexible solution to services deployment. However, these solutions suffer from several disadvantages: (i) the slow deployment time of services in virtual machines, and (ii) virtual appliances crafted by developers tend to be inefficient for deployment purposes. Researchers target problem (i) by advancing virtualization technologies or by introducing virtual appliance caches on the virtual machine monitor hosts. Others aim at problem (ii) by providing solutions for virtual appliance construction, however these solutions require deep knowledge about the service dependencies and its deployment process. This dissertation aids problem (i) with a virtual appliance distribution technique that first identifies appliance parts and their internal dependencies. Then based on service demand it efficiently distributes the identified parts to virtual appliance repositories. Problem (ii) is targeted with the Automated Virtual appliance creation Service (AVS) that can extract and publish an already deployed service by the developer. This recently acquired virtual appliance is optimized for service deployment time with the proposed virtual appliance optimization facility that utilizes active fault injection to remove the non-functional parts of the appliance. Finally, the investigation of appliance distribution and optimization techniques resulted the definition of the minimal manageable virtual appliance that is capable of updating and configuring its executor virtual machine. The deployment time reduction capabilities of the proposed techniques were measured with several services provided in virtual appliances on three cloud infrastructures. The appliance creation capabilities of the AVS are compared to the already available virtual appliances offered by the various online appliance repositories. The results reveal that the introduced techniques significantly decrease the deployment time of virtual appliance based deployment systems. As a result these techniques alleviated one of the major obstacles before virtual appliance based deployment systems.

The task of selecting and developing a method of Human Computer Interaction (HCI) for a Condition Based Maintenance (CBM) system, is investigated in this thesis. Efficiently and accurately communicating machinery health information extracted from Condition Monitoring (CM) equipment, to aid and assist plant and machinery maintenance decisions, is the crux of the problem being researched. Challenges facing this research include: the multitude of different CM techniques, developed for measuring different component and machinery condition parameters; the multitude of different methods of HCI; and the multitude of different ways of communicating machinery health conditions to CBM practitioners. Each challenge will be considered whilst pursuing the objective of identifying a generic set of design and development principles, applicable to the design and development of a CBM system's Human Machine Interface (HMI).

The goal of virtual human simulation is to produce behaviour which is visually indistinguishable from reality. However, while various aspects of human behaviour have been extensively explored, there has been little research into behaviour motivated by moral objectives. Virtual characters are often simulated in charged environments, where rational behaviour is greatly challenged and in reality moral judgement plays a significant role. This thesis explores and presents novel solutions to the problem of simulating ethical behaviour. The research is presented in three stages. In the first, a reactive approach to the simulation of ethics inspired by Braitenberg’s Vehicles is described. This is achieved by iteratively augmenting a Type 3 Vehicle with new sensorimotor connections to produce further emergent results. The approach was capable of producing behaviour which was consistent with various normative specifications. Although successful, the Braitenberg Vehicle approach yields behaviour which is visually robotic. This is explored in the second stage of the research where a novel method for modelling affective behaviour is presented. In the third stage, a new architecture for the simulation and modelling of ethical behaviour called Trilogy is presented. This approach, inspired by classical and contemporary tripatriate theories of thought, serves as a computational substrate to bring together the ethical and affective simulation methods previously developed in stages one and two. Two experiments are conducted to evaluate the architecture where participants observed videos of simulated behaviour. The first experiment tests the hypothesis that the inclusion of affective states make an agent’s ethical behaviour more believable, and this was demonstrated to be the case. The second experiment compares the behaviour of the ethical agents against agents which are not ethically motivated. The results of both experiments demonstrate that the approach is capable of producing visually ethical behaviour beyond chance accuracy.