Recent statistics have suggested that a proportion of drivers are killed or seriously injured on UK roads due to feeling nervous, uncertain or panicked whilst driving. The literature into negative emotions has primarily focused on the relationship between anger and driving. Not including the literature on driving phobias and fears after a motor vehicle accident, the literature on the relationship between anxiety and driving is limited and inconclusive. The aim of the thesis was to investigate the effects of both state and trait anxiety on driving behaviours and autonomic reactions using studies with varying methodologies. Chapter 2 describes a questionnaire study, which found that whilst driving anxiety can have a substantial impact on anxiety related thoughts, behaviours and active avoidance, trait anxiety had slightly differential effects regarding social concerns, aggressive reactions and anxiety and avoidance of specific driving situations. Chapter 3 established, in a laboratory study, that whilst trait anxiety predicted various self-reported driving reactions, it did not affect levels of behavioural or autonomic reactions to driving video stimuli. Chapter 4 expands on these findings with a study that demonstrated reductions in high frequency heart rate variability, indicating a potential lack of emotional regulation within this context. The research was then taken into a simulated environment, where state and trait anxiety were investigated. The studies reported in Chapters 6 and 7 found limited impacts of threatening instructional sets on levels of state anxiety, but demonstrated that increases in state anxiety could lead to changes in behaviour and skin conductance levels. Finally, a simulator study reported in Chapter 8 demonstrated that whilst trait anxiety did not affect driving behaviours, it did affect levels of attentional control and processing efficiency. This leads into a discussion of the theoretical and practical implications of these findings. Particular focus is given to the benefits of interventions and exposure therapies, and it is argued that different types of intervention would be more beneficial depending on levels of state or trait anxiety.

The UK has adopted the concept of sustainable development and the construction industry is playing a key role in improving the efficient use of materials. The aim is to minimise the waste generated and maximise quantities of materials reused or recycled, minimising raw material consumption. Using Reclaimed asphalt pavement (RAP) is a rehabilitation technique which involves recycling materials from asphalt layers that have already been in service. This reduces the use of new bitumen and aggregates and avoids disposal. However, UK pavements constructed prior to 1980 or surfaced in the late 1980’s may contain tar, a carcinogenic substance that cannot be reheated and, therefore, cannot be recycled into hot mix asphalt (HMA). Recycling these pavements into unbound materials is also prohibited; consequently, disposal or cold recycling are the two available options. Cold recycling of asphalt is a proven technique that reduces material disposal and raw material and energy consumption. The reduction in energy consumption is largely achieved by avoiding aggregate drying and mixing of the material at ambient temperature. In this sense, using cold recycled bound materials (CRBMs) becomes the most economic and sustainable option. However, despite the increasingly common use of CRBM in roads, the specifications for the use of these materials in airfields are under-developed and there is no guidance to ensure that pavement design with these materials is trustworthy. This is the reason why this Thesis focuses on airfield pavement design with CRBM. The aim of this investigation is to develop a design methodology to use CRBMs in airfield pavements. For this purpose, the objectives were to review past experience on performance of these materials, measure and analyse the effect of key variables on performance to establish material limitations and develop a design methodology, proposing design guidance for airport authorities and practitioners. To achieve the project aims and objectives, a literature review was carried out focusing on pavement engineering, airfield pavement design and CRBM. The objective was to gain sufficient knowledge on key areas to conduct the research. Based on this literature review it was decided to use foamed bitumen as the cold technology and Kenlayer as pavement analytical design software. It was also found that the current design methodology for using CRBM in airfields is to conservatively equate material properties to those of a HMA commonly used in airfield base course (HDM50). Therefore, this practise should be analysed to decide if it is correct or if it can be improved. Subsequently, a laboratory programme was established to analyse CRBM mechanical properties and, therefore, understand the material’s behaviour and performance under cyclic loading. RAP, fly ash, cement and foamed bitumen were used to manufacture laboratory specimens, compacted with a gyratory compactor. These specimens were tested to analyse densities, air voids, stiffness, strength, permanent deformation and fatigue. For developing a new design methodology, Kenlayer was used to analyse strains and stresses within the airfield pavement. The first step was to ascertain Kenlayer adequacy and establish inputs related to loading, traffic and subgrade condition. For this purpose, 96 case studies were analysed with HMA, with different aircraft types, traffic and subgrade conditions. These cases were compared to those of a well-established airfield design guide, namely DMG 27. Then the software could be used to model pavements containing CRBM and with the knowledge gained in the laboratory about its behaviour, establish layer thicknesses to bear traffic during the pavement design life. With the results obtained from the laboratory investigation it was concluded that CRBM mixes have acceptable properties for use in airfield pavements. Resistance to permanent deformation, fatigue, temperature susceptibility and durability results show that these materials give reasonable performance; however, they differ from conventional hot mixes. Thus, current practice can be improved, justifying the need for design guidance for using CRBM in airfields. As fatigue is one of the main failure modes in asphalt mixtures and flexible pavements, a deeper study into fatigue behaviour of CRBM was carried out using Indirect Tensile Fatigue Tests (ITFT) in strain control mode and Wheel Track Test (WTT). The results showed different failure mechanisms for CRBM from those of HMA; thus, a new failure criterion was established. In HMA the failure criterion of 50% stiffness reduction is related to the appearance of macro cracks. CRBM develops dispersed micro-cracking that lowers the mixture stiffness without producing macro cracks until late in the material’s life. Macro cracks only tend to appear at 70% stiffness reduction; therefore, this was established as new failure criterion for CRBM. Once CRBM properties were defined, the pavement structure could be modelled. The results obtained from HMA modelling showed that the software and the inputs selected were appropriate for this investigation. Then the HMA base properties were substituted with CRBM properties obtained in the laboratory. The results showed that DMG 27, Chart 7, can be used for designing airfield pavements using CRBM increasing the base thickness by 9%, with a minimum Dry Lean Concrete (DLC) layer of 150 mm. A deterioration analysis was also carried out with the design software. In this case the aim was to analyse how strains distribute within the CRBM layer and how this affects the pavement life. With these analysis, it was highlighted how different CRBM behaves compared to HMA. Strains distributed linearly within the HMA layer; however, this does not happen with the CRBM. Moreover, this analysis showed how fatigue data can be used to obtain a more accurate pavement life taking into account different strain levels. Nevertheless, the study carried out here is based on laboratory performance of one type of CRBM. There is need for further investigation to establish a relationship between fatigue behaviour in the laboratory and the field and confirm how micro cracking affects the bearing capacity of the CRBM layer, establishing shift factors to optimise CRBM layer thickness. Moreover, the laboratory study has been carried out analysing CRBM in the same way as HMA; therefore, further study is needed to analyse the adequacy of the testing methodology. Also, modelling has been done comparing one CRBM to one HMA, namely HDM50; therefore, further investigation is needed to open the model to other HMA. Consequently, the design guidance presented here is a first step towards an airfield pavement design guide and further study is needed to optimise it.

Ice accretion on aerofoils is a problematic phenomenon affecting power lines, ships and aircraft wings. This work thus undertakes an experimental and computational investigation into the formation and adhesion of ice on aerofoils. An experimental setup to test the adhesion strength of ice was designed and tested for repeatability and the effect of temperature on it. It was found that the ambient temperature has a profound effect on the adhesion strength, possibly due to dependence on the heat transfer mechanism through an amorphous liquid-like layer between ice and substrate. The tests were expanded to determine the effect of contact angle parameters on the icephobicity of 14 nanocoatings. It was found that the surface should possess high receding contact angle and low CAH to reduce adhesion thereby reducing the ice-substrate contact points. Hydrophobicity and icephobicity may not necessarily be dual characteristics of a surface unless the aforementioned criteria is satisfied. Anti-icing tests on the same coatings showed that the freezing time of a droplet on the surface reduces with an increase in static contact angle. To understand the role of mixed ice, a one dimensional model is introduced to measure the accretion of mixed, rime and glaze ice on an aerofoil. This process occurs in four distinct stages and the effect of atmospheric parameters on the transition time between different growth types and height is determined. This mode was developed further to include a convective term to determine the profile of ice when rime grows above glaze/mixed with water flowing inside. This is a first step towards understanding the links between porous structures, ice structures and runback water that can generate interesting icy structures. This work forms part of the ICECOAT project funded by the EU Framework 7 CleanSky programme under grant award JTI-CS-2012-02-SFWA-01-051.

The current thesis aimed to explore the novice driver problem from a psychological perspective. The ultimate aim was to enhance knowledge and understanding which may advise how to improve novice driver safety. The novice driver problem is a worldwide trend; which in the UK involves one in five newly licensed drivers being crash involved in their first year of driving (Maycock & Forsyth, 1997). Research suggests that both age and inexperience are the major factors of novice driver crash risk; although inexperience has been shown to be the more important (Maycock, 2002). Crash risk reduces dramatically as drivers gain experience of driving after licensure, although what drivers are psychologically learning through experience is not yet understood. Using the Task-Capability Interface model (Fuller, 2005) to conceptualise driving, the current thesis sought to extend the theory by exploring the psychological processes through which drivers appraise risk and how this shapes a decision and behavioural response. Study One reports that there are two distinct ways in which drivers appraise risk, which supports theory proposed by Slovic et al. (2004): risk as feelings and risk as analysis. Current neurological theory, in the form of the Somatic Marker Hypothesis (Damasio, 1994), supports the role of feelings and emotion as an evolved automated system of human risk appraisal that biases judgement and decision making. Studies Two and Three investigated emotional appraisal of hazards between novice and experienced drivers through physiological skin conductance. The results suggest that novice drivers fail to emotionally appraise developing hazards when compared to experienced drivers. Study Three demonstrated that novice drivers who had driven less than 1000 miles had physiological anticipatory scores similar to learner drivers whereas novices who had driven more than 1000 miles had scores approaching those of experienced drivers. This demonstrated a learning curve mediated by driving experience. As a result of the thesis, it is suggested that further research into the role of feelings and emotion in learning to drive is performed. The implication of the results for graduated licensing is also discussed.

Climate change is recognised worldwide as a major concern, with serious repercussions. Observed temperature rises are increasingly being linked to human activity. Evidence indicates a strengthening vehicle-orientated society, with negative implications for climate change. To achieve the targets to mitigate climate change, governments have undertaken a series of environmental reforms to their policy measures. Pricing signals, designed to shape individuals' behaviour with incentives/disincentives, are provided via government-led fiscal policy. This research focuses upon those measures targeting individuals' future vehicle purchasing behaviour. Environmental savings are achieved by purchasing a relatively lower emission vehicle than the vehicle most often used at present. This research explores the weighting of situational and psychological factors shaping individuals' future vehicle purchasing decisions. The modifications to current taxation policy, deemed necessary to start thinking about, seriously think about and definitely buy a lower emission vehicle, are also investigated. The potential influence of hypothetical policy measures to further encourage a lower emission vehicle purchase is also considered. To address the aforementioned research topics, a postal questionnaire survey was administered to a sample of Scottish motorists. 1,336 responses were collected, equating to a response rate of 28.3%. Cluster analysis was applied to the overall population, and the differences subsequently evaluated. For the Scottish motoring population, situational factors were generally more influential than psychological factors in informing individuals' future vehicle purchasing decisions. Disaggregating the population into segments indicates variation in the factors driving individuals' future vehicle purchasing behaviour. Revised behavioural models were presented to visually demonstrate the differences. The strength of psychological constructs provides insight into the preparedness of individuals to purchase a lower emission vehicle, and thus the type of policy interventions most effective in influencing future vehicle purchasing behaviour. Results indicate a sizeable potential for using vehicle excise duty, value added tax, hydrocarbon oil duty and the plug-in car grant to shape individuals' future vehicle purchasing decisions towards a lower emission vehicle. This reported influence was generally found to increase as individuals become more prepared to purchase a lower emission vehicle in the future. Tax incentives were identified as more influential than disincentives in shaping individuals' future vehicle purchasing behaviour towards a lower emission vehicle. This is particularly so as individuals become more prepared to purchase a lower emission vehicle. In keeping with established psychological theory regarding behaviour change, individuals were found to require a progressively greater tax incentive/disincentive to advance through the behaviour change process towards purchasing a lower emission vehicle. Those individuals most prepared to purchase a lower emission vehicle were generally found to require the lowest incentive/disincentive to change their future vehicle purchasing behaviour towards such a vehicle. Motorists were found to be most influenced by hypothetical policy measures reoccurring throughout the period of vehicle ownership, followed closely by those present at the time of vehicle acquisition. Across all segments, a proposed ‘feebate' system presents the best opportunity for shaping future vehicle purchasing behaviour towards a lower emission vehicle. However, the reported influence of hypothetical policy measures was largely found to increase as individuals become more prepared to purchase a lower emission vehicle. Collected results are discussed in context of past research and current transport policy. A series of recommendations, directed towards both future researchers and policy makers, are then presented.

Passenger safety within vehicles is a priority for automotive companies in order to meet both the regulations and customer expectations. The safety critical materials, those used for absorbing energy during a crash, are simulated with FEA in order to design and improve components and to reduce the requirement for physical testing, which in turn saves on development time and cost. The simulation capabilities of Jaguar Land Rover were identified as lacking in accuracy for energy absorbing materials. Quasi-static and dynamic testing of expanded polypropylene as coupon samples and vehicle components was carried out to assess their stress-strain responses, energy absorption capabilities and strain rate effects. Using the properties within FEA the mechanical behaviour of the material was predicted and validated against the physical testing. Updated material models were implemented back into Jaguar Land Rover that fully incorporate strain rate effects and contain reliable, traceable input data. The material models require stress-strain curves, density, material modulus and un-loading characteristics. A test methodology has been implemented into Jaguar Land Rover for characterising energy absorbing materials, something that was previously unavailable. This includes the use of three machines, a low strain rate Instron 5800R, a high strain rate Drop Tower and a Very High Strain rate (VHS) testing rig; each used to understand the effect of compression testing at a range of strain rates and under decelerating/constant velocity impact conditions. Energy absorbing materials were sourced from two foam manufacturers. It was shown that different manufacturer’s material performed differently, even when supplied to the same requirement and manufactured from the same precursor. Computed tomography under synchrotron radiation was utilised to inspect material differences, identifying possible causes for stress-strain changes under compression. From the images a 3D mesostructural model was created to predict the material performance during deformation. As a result Jaguar Land Rover procedures were changed, increasing FEA capabilities and increasing the utilisation of foam within the vehicle. New test procedures were implemented for characterising future energy absorbing materials. The simulation and computed tomography work will help towards the understanding of foam compression mechanisms.

The increasing size and complexity of road vehicles used for the transport of day-old chicks has raised concerns about the thermal environment achieved within the load space of such transporters. Current designs have not been based on scientific infonnation or evaluation, making new development difficult for the industry. To address this lack of information, given the high cost of these vehicles, modelling of this situation would seem a viable option. The work presented in this thesis illustrates the effectiveness of experimental and numerical modelling. Results collected using an ultrasonic anemometer from a full-scale isothennal model of a particular load space and ventilation system are presented for different load configurations of empty chick boxes. These cases were also sinmlated using commercially available computational fluid dynamics software [PHOENICS with high-Re k-e turbulence model and hybrid convective differencing]. These numerical model results were then validated against the experimental data using a novel statistical method based on the repeatability of the experimental data. In further numerical sinmlations a heat load model representing the presence of the chicks, was also incorporated and the likely thermal environment assessed. These numerical results were used to assess the ventilation delivered to each chick box based on the predicted mean air velocities. These results indicated that experimental modelling was a time consmning process with difficulties of accessibility for instrumentation within a loaded vehicle. Numerical sinmlation gave a good approximation of the experimental data but required a nwnber of significant assumptions and simplifications to be made. The main area of disagreement with the experimental data was in the predicted turbu1ence levels. Ventilation rates and thermal conditions within the load space studied suggested an adequate environment is achieved for normal journeys but that the potential for heat stress exists. Further field work to validate these findings is suggested.

The theoretical development of four computer models of resistojet nozzle performance is reported. Five main energy loss processes are accounted for; these are (i) frozen chemical rate processes, (ii) finite rate vibrational relaxation, (iii) incomplete expansion, (iv) viscous flow and (v) radial flow. The nozzle flow is assumed to be composed of an inviscid core and a viscous boundary layer, where the boundary layer is represented by the patching together of similar solutions of the laminar boundary layer equations. General similar boundary layer equations have been developed which include the radial dependences accounting for transverse curvature. Four simplified classes of similar equations are identified, and extensive solutions have been obtained for the Falkner-Skan equation and a modified Falkner-Skan equation which includes the effects of transverse curvature, over the range of pressure gradient parameter, g, from 0. to 10. Vibrational relaxation is modelled by using an approximate sudden freezing criterion. Performance predictions are presented for H2, CH4, CO2 and NH3 for plenum temperatures extending from 300 to 3000°K and plenum pressures from 200 to 10 kNm-2. A wide variety of nozzle geometries is also considered. The results are compared with the predictions of the slender channel model of Rae and with experimental measurements.

Deleterious effects such as surface heating and turning moments can arise as a consequence of the impingement of thruster plumes with spacecraft surfaces. Such thrusters are normally fired for attitude control. The prediction of such effects must be undertaken at the design stage of the vehicle. In this study, the modelling of such plumes was undertaken. The following prediction techniques were implemented into computer programmes: (a) the Simons model, (b) the Method of Characteristics (MOC), and (c) the Direct Simulation Monte Carlo method (DSMC). The first two methods are derived from continuum equations whilst the third adopts a discrete particle approach. Several DSMC schemes exist for treating the collisional behaviour of the gas, and it was unclear which would be best suited for the intended application. A thorough assessment of the implementation and performance of several such schemes was therefore completed. Having determined the most suitable DSMC scheme, the three modelling techniques were then applied to the isentropic core expansion of a small hydrazine thruster plume. It was found that significant errors occur in the determination of impingement quantities through application of the continuum methods in the flow regime lying between the continuum and free molecular limits. The DSMC technique was also used to calculate the nozzle lip and backflow expansion regions of the same hydrazine thruster. A significant degree of backflow was found with flow angles of up to 140º. The sensitivity of the calculations to the conditions initially assumed were assessed and found to be important.

The research presented in this thesis explores the prediction of noise propagation and radiation in turbofan engine intakes and bypass ducts, and the optimisation of noise attenuation by using acoustic liners. A commercial FE/IE code ACTRAN/TM is used within two shell programs; B-induct for bypass ducts and ANPRORAD for intake ducts. An automated liner impedance capability has been demonstrated by exploiting an optimisation suite, SOFT. Automated liner impedance optimisations to maximise the liner insertion loss have been performed for a uniform bypass duct with a multimodal noise source, by using B-induct within SOFT. Results show that, multi-segment liners are effective at low frequencies when few acoustic duct modes are present and less so at high frequencies when many modes are present. Other results show that, at high frequencies, having different liner impedances on the inner and outer walls could be more effective than axially segment liners. An automated liner impedance optimisation has also been performed for a realistic bypass duct, and an A-weighting has been considered. Far field noise levels predicted by using ANPRORAD analysis have been validated against measured data from rig and engine tests. The predicted results are in good agreement with the measured data when the noise source is calibrated using in-duct measured values. This demonstrates that ANPRORAD is a viable methodology for intake noise predictions in industry. ANPRORAD has also been applied to investigate the effect of the intake geometry on low-frequency acoustic reflections in the intake, and integrated within SOFT to perform automated liner impedance optimisations to minimise acoustic reflections to the fan.