Sensors are playing an increasingly important role in our lives, and for these devices to perform to their maximum potential, they need to work together. A single device can provide a single service or a fixed set of services but, when combined with other sensors, different classes of applications become implementable. The vital criterion for this to happen is the ability to bring information from all sensors together, so that all measured physical phenomena can contribute to the solution. Mediation between applications and physical sensors is the responsibility of sensor network middleware (SNM). Rapid growth in the kinds of sensors and applications for sensors/sensor systems, and the consequent importance of sensor network middleware has raised the need to relatively rapidly build engineering applications from those components. A number of SNM exist, each of which attempts to solve the sensor integration problem in a different way. These solutions, based on their ‘closeness’ either to sensors or to applications, can be classified as low-level and high-level. Low-level SNM tends not to focus on making application development easy, while high-level SNM tends to be ‘locked-in’ to a particular set of sensors. We propose a SNM suitable for the task of activity monitoring founded on rules and events, integrated through a semantic event model. The proposed solution is intended to be open at the bottom – to new sensor types; and open at the top – to new applications/user requirements. We show evidence for the effectiveness of this approach in the context of two pilot studies in rehabilitation monitoring – in both hospital and home environment. Moreover, we demonstrate how the semantic event model and rule-based approach promotes verifiability and the ability to validate the system with domain experts.

In order to meet demands in mobile broadband and to bridge the digital divide a new technology, namely WiMAX, was introduced in 2004. However, in order to increase the financial return on the investment inWiMAX, service operators need to make every effort in designing and deploying the most cost-effective networks. This thesis presents a novel dimensioning technique for WiMAX technology which takes the dimensioning problem to a new level and produces more accurate results in comparison to the traditional methods. Furthermore, a novel decomposed optimization framework for the WiMAX network planning is introduced which subdivides the overall problem into three distinct stages consisting of the network dimensioning stage which besides the primary task of evaluating the financial requirements produces a good starting network solution for the subsequent stages (Stage 1), initial sectorization and configuration of the network (Stage 2) and final network configuration (Stage 3). The proposed framework also solves two fundamental problems, which are cell planning and frequency planning, simultaneously. The feasibility of the final network solutions are then evaluated by OPNET simulator.

Volunteer Computing is a new paradigm of distributed computing where the ordinary computer owners volunteer their computing power and storage capability to scientific projects. The increasing number of internet connected PCs allows Volunteer Computing to provide more computing power and storage capacity than what can be achieved with supercomputers, clusters and grids. However, volunteer computing projects rely on a centralized infrastructure for distributing data. This can affect the scalability of data intensive projects and when the projects participants increases. In this thesis, a new approach is proposed to incorporate P2P techniques into volunteer computing projects and apply trust management to optimize the use of P2P techniques in these projects. This approach adopted a P2P technique to form a decentralized data centres layer based on the resources of participants of volunteer computing projects. VASCODE framework is based on Attic File System to enable building the decentralized data centres and makes use of trust framework to provide the necessary data to users to select the optimum data centres for downloading data. Empirical evaluation demonstrated that the proposed approaches can achieve better scalability and performance as compared to the central server approach used in BOINC projects. In addition, it shows that clients with the support of trust framework have reliable and consistent download times because using trust allows them select the optimum data centres and avoid the malicious behaviour of data centres.

The use of sound to communicate information as part of a user interface has been an active research area for several years. Research has shown that sound can be concurrently presented to users to increase the bandwidth and rate of data presentation. However, when sounds are concurrently presented, they may interfere with each other, such that determining the data encoded in the sound becomes difficult. Modifications to the sounds can help to avoid such interference, but due to the nature of the sounds the impact of the modifications may be constrained. This thesis investigates such interaction with concurrently presented earcons. One experiment investigates how the identification of earcons is affected by the number concurrently presented. It was found that increasing the number of earcons concurrently presented lead to a significant decrease in the proportion of earcons and their attributes successfully identified by participants. With identification falling from 70% correct for one presented earcon to 30% for four concurrently presented earcons. A second experiment identified how modifications to the design and presentation of concurrently presented earcons affected their identification. It was found that presenting each earcon with a unique timbre as well as introducing an onsettoonset delay of at least 300ms caused a significant improvement in earcon identification, and the timbre encoded attribute of earcons. However overall identification levels remained low at around 30%. Two further experiments investigated the impact of spatialisation on concurrent earcon identification. They showed that spatial presentation of earcons which did not incorporate the findings of the previous experiment significantly improved identification of earcons and the register encoded earcon attribute, over earcons that were not spatially presented but did incorporate the findings of the previous experiment. Another experiment showed that spatial presentation of earcons which incorporated the unique timbre and 300ms onsettoonset modifications significantly improved the identification of the timbre encoded earcon attribute, although overall identification remained low. These four experiments yielded a set of guidelines for concurrent earcon presentation. Due to the nature of those experiments however, a further experiment was conducted to determine the impact of the guidelines on more ecologically valid tasks. A set of modified and unmodified earcons which represented entries in a mobile diary system were compared. Overall task accuracy remained low, although participants rated the modified earcons to require significantly less subjective workload.

published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

(Uncorrected OCR) Abstract of Thesis entitled 'Virtual Links for Multicomputers' Submitted by Siu Kit Wai for the degree of Master of Philosophy at Univsersity of Hong Kong in October 1996 In order to increase computation power, multiple autonomous computers or processors are connected to form a multicomputer. The performance boost is the result of exploiting in parallel the processing power available in individual processors. Parallel processing, however, requires the cooperation among the processors, which implies interprocessor communication. The efficiency of such communications is limited by the bandwidth and number of communication channels between directly connected processors. Multiple processes on a processor share a few hardware communication links/channels to communication with processes executing on a different processor. Effective and efficient sharing of channels is important for the overall system performance; hence it is important that the sharing be properly managed. When the sharing is not provided by the hardware, it can be provided in software at system level. Without a managing component, processes need to be programmed to flight for and gain exclusive access to the communication links. This is usually not effective, error-prone, and could reduce the overall performance of processes executing in the processor. Flexibility is a main advantage of providing a channel-sharing mechanism at system level. Parameters such as packet size, and configuration of the system can be customized and tuned to meet the communication characteristics of different applications. In this project, we investigate how link sharing can be provided at system level. Our approach is based on idea of virtual links. The system is designed to be as transparent and easy to be used as possible. We will discuss how different parameters and configurations affect the system functionality and performance. We also compare this software solution to other existing solutions including a hardware solution. ii / abstract / toc / Computer Science / Master / Master of Philosophy

published_or_final_version / Computer Science and Information Systems / Doctoral / Doctor of Philosophy

This thesis presents an architecture, which we call GRUE, for intelligent agents in real-time dynamic worlds. Such environments require agents to be able to flexibly adjust their behaviour to take into account changes in the environment or other agents’ actions. Our architecture is based on work done in robotics (Nilsson, 1994; Benson and Nilsson, 1995; Benson, 1996), which also deals with complex, dynamic environments. Our work focuses on goal arbitration, the method used by the agent to choose an appropriate goal for the current situation, and to re-evaluate when the situation changes. In the process, we have also developed a method for representing items in the environment, which we call resources, in terms of their properties. This allows the agent to specify a needed object in terms of required properties and use available objects with appropriate properties interchangeably. We show that the GRUE architecture can be used successfully in both a typical AI test bed and a commercial game environment. In addition, we have undertaken to experimentally test the effects of the features included in our architecture by comparing agents using the standard GRUE architecture to agents with one or more features removed and find that these features do improve the performance of the agent where expected.

Participatory sensing is an emerging field that uses pervasive technology to create new forms of sensing networks combining people, personal devices, and other sensors. Pervasive computing technology forms an essential component, used to report data and coordinate activities. This thesis reviews research in participatory sensing and key fields related to it: pervasive computing, observation networks and public engagement with science. After examining wider issues in sensor-based interaction from pervasive computing literature, this thesis investigates human-sensor dialogue; specifically how to develop new forms of dialogue in future participatory sensing experiences. The term 'dialogue' is used in broad sense, encompassing affordances and ongoing relationships between sensors and users. The thesis examines participatory sensing activities centring on two studies involving groups of young people collecting and visualising environmental sensor data using automatic and manual sensors. Participant observation methods are used for in-situ, naturalistic evaluation using observations, video footage and system logs and data. A framework for human-sensor dialogue is developed as a tool to help analyse the dialogue in participatory sensing experiences and inspire new forms of dialogue in future experiences. It highlights five activities to which dialogue can relate: planning, testing, navigation, capture and reflection. These are interleaved throughout an experience, affecting how it takes shape and resulting from the design of the devices and the whole experience. The framework is demonstrated by applying it to the experiences in the previous two studies. The framework is used to prototype a new experience intended for longer term engagement. It is used to elicit requirements for the new experience, structuring the activity and highlighting the desired transitions. The resulting prototype application is described, outlining the activity setup, key features and technical details. This application uses handheld devices as mobile sensors, wirelessly connected to fixed environmental sensors, which collect, process, and store the restating data.

Recent developments in wireless communication, mobile computing, and sensor technologies have prompted a new vision of the world in which we live. As witnesses the effects of Moore's law, which are evident in many aspects of innovative technical opportunity, such as cost, size, capacity, bandwidth, etc. These advances allow us to build new types of human-computer-environment interaction in augmented physical spaces. Ideally, mobile computing devices can go with people so that they can access information on the move as being constantly connected to the digital space. Sensor technologies enable mobile computing devices to sense their users and environments. This increases the interaction bandwidth between a human and a mobile computing device. The development of context-sensitive mobile computing systems requires considerable engineering skills. None of the existing approaches provides an effective means of obtaining location and environmental information using "standard" hardware and software. This raises the entry level of discovering more about this type of interaction to the designers. In addition, it is important to stress that relatively little is known about the usability problems that might arise from interaction with these different context-sensitive mobile computing applications. The focus of this thesis is on the development of a prototyping environment for context-sensitive mobile computing. This thesis makes two contributions. The most significant contribution is the presentation of the Glasgow Context Server (GCS). It has been specifically designed to address the concerns mentioned above. It successfully integrates an off-the-shelf radio Local Area Network (LAN) with the infrared sensors that have been a feature of many previous context-sensitive mobile computing applications. The GCS is intended to help interface designers validate the claimed benefits of location sensing, location disclosing and environment sensing applications. The second contribution is the working applications, in particular, a web-based annotation system for physical objects and a shopping assistant built upon the GCS environment. These demonstrations are used to evaluate the GCS approach and point out the challenging issues in computing technology as well as usability concern. The hope is that this research can provide interface designers with an in-depth reference to a prototyping environment for context-sensitive mobile computing applications.