Studies of interception have shown that participants expect free-falling targets to descend vertically and accelerate at g (9.81 m/s2). Visuomotor delays render motor commands obsolete in such rapidly changing situations, so predictive control is necessary. Internal models have been proposed as a mechanism to predict the future position of free-falling objects. Internal models are predictive systems that provide input to the motor and sensory systems, and are acquired by the CNS from experience. The overall aim of this thesis was to investigate the existence of a possible internal model of gravity and to explore its directional and acceleration amplitude aspects. This thesis is the first study to investigate directional and amplitude aspects of such a model by systematically varying stimulus target kinematics. In the first two experiments, participants performed visually guided tracking of realistic virtual stimuli. In experiment 1, stimuli accelerated at g but moved in different straight-line directions. In experiment 2, stimuli always descended vertically but with different accelerations (as percentages of g). Tracking was by finger pointing, laser pointing, gaze tracking in isolation or gaze tracking with concomitant manual or laser tracking. In the absence of on-screen feedback of indicated position (i.e. non-laser trials), tracking was generally tuned for targets that a) descended vertically (or tended increasingly to vertically downwards over time) and b) accelerated at g or slightly less than g. In the third experiment, participants judged whether a target accelerating at g was moving vertically, or to the left or right of the vertical. The stimuli from experiment 1 were used. I found that a) participants’ reports were influenced by an expectation that gravity would affect the trajectory even when there is visual information to the contrary (i.e. an effect of gravity was expected on observed trajectory); and b) physics expertise yielded no difference in performance suggesting that performance, based on an internal model of gravity, is determined by experience of seeing things fall in the real-world under gravity, rather than by intellectual understanding of gravity. In the fourth experiment, participants judged whether a target accelerated at less than g, at g, or greater than g. The stimuli from experiment 2 were used. As with experiment 3, I found no effect of physics expertise and only weak evidence in support of an internal model of gravity. I conclude that the CNS is likely construct and maintain an internal model of gravity that predicts the future position of free-falling targets to be in a ‘real-world' manner – acceleration at 99% or 100% of g and vertically downwards or in a direction tending increasingly to vertically downwards over time. I found no evidence for ‘direct perception’ (observation yielding first-order time-to-contact information). In the final conclusion I briefly discuss alternative possibilities for predictive motor control.

This thesis proposes that on-demand mapping - where the user can choose the geographic features to map and the scale at which to map them - can be supported by formalising, and making explicit, cartographic generalisation knowledge in an ontology. The aim was to capture the semantics of generalisation, in the form of declarative knowledge, in an ontology so that it could be used by an on-demand mapping system to make decisions about what generalisation algorithms are required to resolve a given map condition, such as feature congestion, caused by a change in scale. The lack of a suitable methodology for designing an application ontology was identified and remedied by the development of a new methodology that was a hybrid of existing domain ontology design methodologies. Using this methodology an ontology that described not only the geographic features but also the concepts of generalisation such as geometric conditions, operators and algorithms was built. A key part of the evaluation phase of the methodology was the implementation of the ontology in a prototype on-demand mapping system. The prototype system was used successfully to map road accidents and the underlying road network at three different scales. A major barrier to on-demand mapping is the need to automatically provide parameter values for generalisation algorithms. A set of measure algorithms were developed to identify the geometric conditions in the features, caused by a change in scale. From this a Degree of Generalisation (DoG) is calculated, which represents the “amount” of generalisation required. The DoG is used as an input to a number of bespoke generalisation algorithms. In particular a road network pruning algorithm was developed that respected the relationship between accidents and road segments. The development of bespoke algorithms is not a sustainable solution and a method for employing the DoG concept with existing generalisation algorithms is required. Consideration was given to how the ontology-driven prototype on-demand mapping system could be extended to use cases other than mapping road accidents and a need for collaboration with domain experts on an ontology for generalisation was identified. Although further testing using different uses cases is required, this work has demonstrated that an ontological approach to on-demand mapping has promise.

The Military Survey of Scotland provides a remarkably detailed and extensive record of the Scottish mainland immediately prior to the fundamental changes wrought by the agricultural improving movement. Frequently utilised as a source by historians and historical geographers, the landscape which it portrays has invariably been accepted at face-value. However, preliminary investigation revealed that both the Original Protraction and Fair Copy were unreliable and this resulted in a programme of research being initiated to ascertain the accuracy of the maps which comprise the Military Survey. Skelton's (1967) dual concepts of map form and content were utilised as a framework for the thesis and this enabled the Military Survey to be examined both as an artifact and as an inventory of the mid-eighteenth century Scottish landscape. A Production/Product matrix was devised and the relative impact of each stage of the cartographic construction process upon accuracy was analysed. Written and cartographic evidence were used in tandem and, where material was not extant, replication was undertaken to generate facsimile documentation. Replication is an original technique, devised and developed to fulfil the specific requirements of this thesis, but which a has potential applications elsewhere in historical cartographic research. The Original Protraction and Fair Copy were differentiated with regard to both planimetric and topographic accuracy and, although the former was found to be more reliable, neither could be recommended as an accurate depiction of the Scottish countryside circa 1750. The incorporation of independent cartographic sources into the Military Survey was investigated and four of the larger settlements were found to have been drawn from pre-existing town plans and to field-mapping data. The rationale behind the creation of the Military Survey was also examined and the generally-held assumption that the intention of the draughting personnel was to produce a military map was discounted. Strong evidence was found to support an alternative hypothesis that the Military Survey was intended as a gift.

Embedding the time-geographic framework within a GIS is accomplished by using the object-oriented analysis and design method proposed by Booch. This method assures the object-oriented decomposition in which the complexity of the concepts developed in the time-geographic framework are transposed to a meaningful collection of objects. These interact in different kinds of scenarios within a <I>spatio-temporal data model</I>. In addition, inheritance has been adopted as the incremental change mechanism within the spatio-temporal data model because of its usefulness in subclassing the evolutionary processes of incremental change within the time-geographic framework. A taxonomy of change is proposed on the basis of the spatio-temporal data model, designed for embedding the time-geographic approach. A version management approach plays an important role in managing changes within the spatio-temporal data model. The version management method developed by Ahmed and Navathe has been selected because of its consistency with object-oriented concepts. The main concepts of this method are described and its incorporation into the spatio-temporal data model is presented in the thesis. The GIS application chosen to evaluate the spatio-temporal model is the study of the evolutionary aspects of public boundaries. Public boundaries represent the line of physical contact between administrative units in Great Britain. The arrangement of public boundaries forms an irregular tessellation of polygons that represent the whole hierarchy of local government and European Constituency areas. Approximately 3,000 changes occur to political boundaries in England every year. The spatio-temporal data model describes the processes which most of the public boundaries would pass through in their lifespan as well as the different evolutionary states which reveal the changes occurring over a public boundary lifespan. Finally, the implementation aspects involved in incorporating the spatio-temporal data model into an object-based GIS are discussed. The Smallworld is used for implementing the spatio-temporal data model and the issues arising from this implementation of the theoretical framework are identified and assessed.

Rapid urbanisation in Kuala Lumpur over the past 25 years has brought its share of problems such as traffic congestion, urban sprawl, rise in noise. pollution, flooding and other environmental issues. The increase in population in developing countries has resulted in increased traffic volumes, and traffic congestion has been a serious problem for citizens of Malaysia for many years. Every year the Ministry of Works Malaysia, through its Highway Planning Unit (HPU). has spent considerable amounts of money to collect census data on traffic volume. After processing the data, HPU publishes its Annual Traffic Volume guide. From 1996 to 1998, for example, the total number of motor vehicles registered increased from 7.7 to 9.1 million, a dramatic increase in the volume of traffic. It is therefore vital to have decision support systems that provide information from the latest traffic-volume database systems. The main objective of this study is to research, design and develop a database structure for traffic volume in Selangor, using a Geographical Information System (GIS) to analyse road traffic volumes in certain areas; it will enable calculation of traffic congestion and provide basic information for road pavement work for future road maintenance. The use of GIS and associated techniques can play an important role in decision-making activities for route transportation systems. GIS techniques have a significant role in the storage, analysis and reporting of data sets. In the traffic volume situation, GIS also allows for the integration of different databases relating to traffic congestion, including both traffic-based data and related land use, demographic, topographic and environmental data. This thesis presents research into GIS processes that will enable us to monitor traffic volumes and the condition of the road pavement in Selangor. The research focuses on GIS development and traffic data collection. The principal objective of this thesis is to propose the development of a system that will help to analyse traffic volume, by using GIS to link data sets by area, thus facilitating interdepartmental information sharing and communication. Both traffic volume and the road transportation system have a strong spatial existence; therefore GIS is an obvious system for use in finding a solution. The results demonstrate that GIS has a crucial role in analysing specific areas of traffic volume for future road maintenance planning. The distribution of congestion in a region is important, and the use of GIS software for database integration, data analysis and data display is extremely advantageous. More specifically, the research considers the use of GIS as a means of analysing the location of traffic factors. including congestion and road surface damage. Furthermore, the identification of traffic volume zones can be displayed on GIS and the identification of alternative routes to alleviate traffic congestion can then be made to avoid further damage to road pavement.

International Relations theory in general, and the globalisation debate in particular, operate with a conception ofspace that contains a number ofproblematic distinctions. Global space and the territorial space of the state are often considered as opposites. Furthermore, the concept of space is predominantly contained within a subject/object distinction which obscures the way in which territory and global space are both 'nature' and 'culture'. In .contrast, this thesis suggests that modem political space is best understood as being based on a cartographic reality established from the 15th to the 17th century. During this period European cartography underwent a transformation establishing a reality of space that conditioned the possibility of developing centralised sovereign territorial states within a unified global framework. This so-calIed modem cartography produced space as an autonomous sphere based on abstract mathematical principles. Through the agency of cartography, space was produced in such a manner that made large scale coordination in, and organisation of, space possible. EmpiricalIy, it is shown how the territorial space of a sovereign state, Denmark, developed in tandem with a coherent global space through a study· of cartographic practice in Europe from 1450-1650. This analysis leads to the conclusion that the notion of globalisation rests on the same spatial reality as that of the state and caution should, therefore, be shown when positing globalisation as a chalIenge to the territorial state system.

A method for the optimal solution for a particular aspect of Global Positioning System (GPS) networks has been devised. This relates to the logistics of the survey. In particular, it is the organisation of the fieldwork that has been addressed. This becomes especially important as the number of receivers used in a GPS survey increases. The minimum is two but there are marked efficiency gains by using at least one additional receiver. The problem addressed is to determine the order in which each GPS receiver should be moved between the points to be surveyed bearing in mind that it is necessary that the receivers have to be at certain points simultaneously so that the required observations are made. Techniques within the field of Operational Research (OR) have been used to solve this problem. The problem has been transformed into a more complex version of the Travelling Salesman Problem (TSP) -a classical combinatorial problem. With this transformation achieved it was possible to analyse the suitability of techniques within the OR field to solve the GPS logistics problem. A method for the optimal solution of the TSP was developed based upon an existing branch-and-bound approach but modified to take into account the more complex problem now being posed. This method, however, would only work for surveys where the surveyorsstarted and ended at a survey point. To be more realistic, the method was further enhanced to allow for a base (not a survey point) from which the surveyors would start and end their surveys together. This worked well, although it was restricted to surveys that were to be completed in one working period. This method, therefore, has been made more realistic by allowing the surveyors to return on a number of occasions to their base, thus simulating a survey lasting for more than one working period. The developed algorithms have been tested on examples with correct results. The above success is limited in that it cannot work for large networks and so an investigation into heuristic approaches was made. A heuristic approach does not guarantee optimality, but usually the solution is very close to it. This line of investigation was carried out as the guaranteed optimal solution is only possible in applications with a few number of points and receivers. In practice, three of four receivers may be used in networks containing over fifty points. For such a large network, a guaranteed optimal solution cannot be obtained in a sensible amount of time. Modern heuristic techniques have therefore been investigated with guidelines for their implementation to solve the GPS logistics problem given: - simulated annealing and tabu search seem to hold the most promise. A new approach based upon the use of a special fractal known as a space-filling-curve was also developed with successful results.

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