The primary objective of this research is to look at ways of resolving the reliability problems of the Cambridge Ring local area network system. The result is a novel design to enhance the Cambridge Ring with fault tolerance by introducing redundant communication paths with dynamic reconfiguration. The proposed Ring-Star system combines the advantages of ring and star networks to create a network which is topologically resilient while retaining the efficient communication advantage of rings.

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In cluttered environments, the overhead view is often preferred because looking down can afford better visibility and coverage. However detecting people in this or any other extreme view can be challenging as there are significant variation in a person's appearances depending only on their position in the picture. The Histogram of Oriented Gradient (HOG) algorithm, a standard algorithm for pedestrian detection, does not perform well here, especially where the image quality is poor. We show that with the SCOVIS dataset, on average, 9 false detections occur per image. We propose a new algorithm where transforming the image patch containing a person to remove positional dependency and then applying the HOG algorithm eliminates 98% of the spurious detections in the noisy images from our industrial assembly line and detects people with a 95% efficiency. The algorithm is demonstrated as part of a simple but effective person tracking by detection system. This incorporates simple motion detection to highlight regions of the image that might contain people. These are then searched with our algorithm. This has been evaluated on a number of SCOVIS sequences and correctly tracks people approximately 99% of the time. By comparison, the exampled algorithms in the OpenCV are less than approximately 50% efficient. Finally, we show our algorithm's potential for generalization across different scenes. We show that a classifier trained on the SCOVIS dataset achieves a detection rate of 96% when applied to new overhead data recorded at Southampton. Using the output from this stage to generate labelled 'true positives' data we train a new model which achieves a detection rate of 98%. Both these results compared favourably with the performance of a model trained with manually labelled images. This achieves a detection rate of greater than 99%.

Formal design methods are becoming increasingly recognised as being useful for specifying complex systems. Incorporating formal methods in the early stages of a design process introduces the possibility of using mathematical techniques, hence improving the effectiveness of a design process. The Z notation has been applied mainly to specifying software, although it has also been used for specifying hardware and general systems. The Z notation fulfils two functions in this thesis. The first function is as a notation for representing specifications of complex systems, and the second function is as a notation for representing implementations of the same complex systems. The suitability of the Z notation for these functions is investigated in three studies. Both the specifications and implementations are represented as unified collections of Schemas that describe the behaviour in response to each set of input conditions. In each of the studies, both the specifications and implementations of the complex system take place at an early stage in a design process. Throughout this thesis non rigorous proof sketches prove that the implementations meet the requirements of the specifications.

This dissertation is concerned with the management and performance issues of those register-insertion (R-I) ring type local area networks (LANs) which employ the message removal by destination node protocol. A typical example of such a network is the Distributed Loop Computer Network (DLCN). developed by Liu et al for fundamental research in the field of distributed computing. After considering the management issues of low cost R-J LANs. the research deals with performance analysis of the dynamically reconfigurable register-insertion (DRR) network. In the first part of this research. a set of management functions is identified which are desirable and can be provided economically by a low cost LAN. A unique feature of the DLCN is that messages are removed from the network by the destination node. that is. messages do not travel whole of the loop. Therefore. it is not possible for a special control node to monitor the data traffic on the network without providing support functionality in each network access unit (NAU). The minimum functionality which must be provided in each NAU is identified in the thesis. A skeleton network was implemented to verify the feasibility of the proposed scheme. A paper describing the findings of this research was published and is reproduced as appendix A. In the second part of this research. a new feature of the DLCN network is introduced. namely. that the performance of a network employing removal by destination protocol can be improved by reconfiguring the network in a particular way. A methodology to find the optimal configuration is developed and is shown. by worked examples. to lead to improved performance. The findings of this research are particularly applicable to the dynamically reconfigurable register-insertion (DRR) network. A paper dealing with the optimisation of a hypothetical fully connected DRR network has been accepted for publication. Another paper. which considers the general case of less than fully connected DRR networks. is to be published. Both papers are reproduced as append ices Band C. Finally. a performance study of the ORR network is undertaken. As there seems to be no published attempt at formal analysis or simulation of a ORR network. a survey of literature dealing with performance study of the basic OLeN is performed. A simulation model of the DRR was then developed and implemented to verify the results arrived at in the previous section. Later. a queueing model of the DRR network. based on the work of Bux and Schlatter [7] is developed and analysed. Both simulation and analysis support the claim that the performance of a DRR network can be improved by adopting the configuration strategy developed in this thesis.

The objective of this thesis is the unified investigation of a wide range of fundamental parallel methods that are transportable amongst pragmatic parallel machines having different number of processors, different periodicity of global synchronization and different bandwidth of inter-processor communication. The computational model adopted is the bulk-synchronous parallel (BSP) model, which abstracts the characteristics of parallel machines into three numerical parameters p, L and g, that quantify, respectively, processors, periodicity and bandwidth - the model differentiates memory that is local to a processor from memory that is non-local, yet, for the sake of universality, does not differentiate network proximity. The BSP parameters p, L and g, together with the problem size n, are employed to measure the performance, and consequently, the transportability of parallel methods across machines having different values of these parameters. We show that optimality to within small multiplicative constant factors close to one can be achieved for a multiplicity of fundamental computational problems by transportable algorithms and data structures that can be applied for a wide range of values of the BSP parameters. While these algorithms and data structures are fairly simple themselves, description of their performance in terms of these parameters is somewhat complicated. The main reward for quantifying these complications, is that it enables software to be written once and for all that can be migrated efficiently amongst a variety of parallel machines. The methods considered in this thesis - both theoretically and experimentally - embody deterministic and randomized techniques for the efficient realization of fundamental algorithms (broadcasting, computing parallel-prefixes, load-balancing, list-contracting, merging, sorting, integer-sorting, selecting, searching and hashing), data structures (heaps, search trees and hash tables) and applications (computational geometry, parallel model simulations and structured query language primitives).

This thesis is concerned with the use of Artificial Immune System (AIS)in the area of Ambient Assisted Living (AAL). The hypothesis for the work presented herein is that the AIS features of self-learning and adaptability address the complex problem of improving the detection of unknown abnormal; behaviour in the long-term monitoring of the elderly. The work presents and affordable Open Hardware Data Acquisition Device that in combination with a Markov chain-based software simulation environment can be used for the collection of human activity data and the generation of necessary information for long-term simulation. The main contributions from the work presented herein relate to the design and use of AIS based solutions, and the selection of appropriate parameter combinations for supervised classifiers. Firstly, a novel seeding technique for AIS is presented that improves the placement of detectors in the search space. Secondly, a novel AIS-based monitoring algorithm, inspired by Hierarchical Temporal Memory architecture, is designed to learn and approximate sensor data to detect and report activity abnormalities. Thirdly, an empirical analysis is carried out to provide a clear understanding of how sampling frequency, segmentation method, window size, and computational load in an area of AAL. Fourthly, a Pareto curve based technique has been devised and demonstrated as a useful tool for the informed selection of parameter combinations to achieve the best possible classification accuracy and computational load. The evaluation of the AIS-based algorithm showed that the detection rate of abnormal activity outperformed the results of supervised classifiers with parameter combinations selected based on the Pareto curve. The results are encouraging and support the decision to introduce the use of AIS for the detection of abnormal activity in AAL environments.

Software mobile agents is a new distributed computing paradigm which was developed to support efficient computing over the Internet. Since its inception there has been a significant research effort to produce concrete agent-based artefacts. This phenomenon resulted in the proliferation of a large number of agent systems, mostly based on proprietary programming languages, each with its own characteristics, peculiarities and assumptions. Hence the agent technology has largely remained hidden and incomprehensible by Internet end users. Moreover the issue of interoperability and integration of agents with existing legacy software has only just started to be addressed by the agent research community in a rather ad hoc way. In this thesis we attempt to design an agent architecture which is independent of any programming language and therefore is directly suitable for Internet end users. The proposed architecture, labelled as Mobile Agent System for Internet Computing (MASIC), addresses several important contemporary issues in agent research. It defines an agent as a container of reusable components that can be copied or moved to other agents. Each agent has a symmetric I/O access control module and is also equipped with associative access collaboration facilities. Additionally every agent contains a navigator module which stores the agent's itinerary plan and provides an interface via which the agent itself or other authorised agents can dynamically adapt the plan to reflect run-time events and constraints. The agent system provides an integrated access control architecture which enables an agent to define customised access control structures that can be fully or partially shared with other agents. Existing access control structures can be combined to create new structures that represent more complex access mechanisms. Agents can discover other agents offering pertinent services via an adaptive, customisable agent discovery architecture incorporated in MASIC. This discovery architecture enables the full interaction of links with queries and supports the definition of access paths which are tightly coupled with access control and. other customised services. MASIC also provides the conceptual architecture of a message-oriented agent communication system integrated with a mobility management scheme. Finally, this thesis presents the design and implementation of a prototype graphical interface which enables the potential user of the system to create, manage and interact with agents in real time. In conclusion the research presented in this thesis aims to provide a comprehensive, language-neutral, secure, collaborative environment within which mobile agents can interact with their peers in order to perform their tasks efficiently while human operators can oversee and manage these activities through a user friendly interface. The architecture is generic in nature as it can support general-purpose, agent-based computations. Its concepts, entities and mechanisms can be fully or partially re-used to provide architectural solutions to challenges in various application domains such as Knowledge Management, the GRID and E-Commerce.