In the drive for lightweighting in many industries, optimum material selection is at the forefront of research. Many solutions are being investigated, including the fabrication of multi-material components. Following a state of the art review of the literature, it has been shown that there is an opportunity to improve basic knowledge and understanding of the characteristics of hybrid steel-FRP materials for lightweight applications. This dissertation explores the potential for designing lightweight automotive steel structures through novel use of lower gauges combined with local reinforcement by fibre-reinforced plastics to achieve desired stiffness performances. The main focus of the work is to provide underpinning research to enable the further understanding of the stiffness performance of hybrid steel-FRP materials, both experimentally and in simulation. This thesis focuses on the characterisation of high strength automotive grade steel (DP600) reinforced with a fibre reinforced polyamide (PA6 GF60) laminate, however, the results are readily applicable for other combinations. The project was achieved through two main phases; each phase consisting of an iteration loop between experimentation and simulation validations. Initial characterisation was achieved using coupon samples in quasi-static three-point bend, cross-validated in simulation providing a trusted material model. Correlating experimental and simulated results showed a potential lightweighting of up to 30 % of a hybrid DP600-GFRP over a DP600 counterpart with a matched stiffness performance. Further characterisation was performed using an idealised automotive component in flexure, confirming a potential lightweighting of up to 30 %. The simulation investigation demonstrated the effect of localised hybrid reinforcements, and identified difficulties in predicting the local geometrical effects of plastic hinging. For an overall application to an automotive body-in-white, these would require further investigating. This thesis has proven that downgauging steel whilst locally reinforcing (intelligent deployment) with FRP patches provides a significant lightweight solution with a matched stiffness performance. A hybrid material model has been validated and the application to an automotive component investigated. This work provides the basic understanding for a direct application in lightweight automotive designs using computer aided engineering (CAE).

This work is a specific investigation into low speed aerofoils. The term “low speed” is normally used to indicate free stream velocity less than Mach = 0.5 and, here, not more than 0.2 M when considering dynamic-stall. This field of investigation, for the QinetiQ aerofoil, has been somewhat ignored till now to the advantage of higher speeds starting from 0.3 M. In order to improve the knowledge of the behaviour of aerofoils under M<0.2 conditions, the University of Glasgow, in cooperation with QinetiQ, carried out two-dimensional aerodynamic tests on a RAE9645 aerofoil in 2002. By the end of November, of the same year, high quality unsteady pressure measurements from dynamic-stall tests were available. The tests were conducted on two different RAE9645 aerofoil models in two different wind tunnels. The first of these data came from the aerofoil that was tested in the Department of Aerospace’s Handley Page Wind Tunnel. The second data set was from tests carried out by QinetiQ on an aerofoil in the Department of Aerospace’s Argyll Wind Tunnel. The objectives of this investigation are divided in three main topics. First part considers the analysis of the data. This means (a) the assessment of the aerodynamic coefficients and consequent analysis of the various features of the dynamic-stall including the critical angle, the pitching moment and stall onset. (b) A comparison of the overall aerodynamic coefficients and (c) the carry out of final analysis of the most important quantities such as Cp deviation, vortex development and convection speed and re-establishment of fully attached flow. The assessment of the all same quantities for the second aerofoil tested by QinetiQ and the comparison of them xxiii with the first model are the objectives of the second part of the project. Hence a most useful comparison of two data sets from two different wind tunnels will be achieved. The third part was to establish the coefficients for the Beddoes third generation dynamic-stall model for the clean aerofoil without any flow control, using both aerofoil data. The Beddoes third generation dynamic-stall model is the last version of a model which has been in constant development over thirty years and is known as the most popular semi empirical method for assessing unsteady airloads such as lift, drag and pitching moment. This applies both to helicopters and wind turbines. The simplicity and undergoing philosophy of this method is its strength, especially compared with the current solution of Navier-Stokes or Euler equations. At the completion of this work, all the coefficients and information necessary for running the Beddoes simulating dynamicstall model were obtained for the RAE9645 aerofoil. At the same time refinements, improvements and new guide lines were pursued in order to make the model easier and more powerful than before. Some of these changes are associated only to low Mach numbers. It has been concluded that the Beddoes’ model has been enhanced to better re-construct the RAE9645 aerofoils data of low Mach numbers.

The increasing importance of satellite navigation technologies in modern society implies that a deeper knowledge and a reliable monitoring of the scintillation phenomena are essential to warn and forecast information to the end users and system designers. In fact, warnings, alerts and forecasting of ionospheric conditions may wisely tune the development of GNSS-based services to obtain the necessary levels of accuracy, integrity, and immediacy for reliable life-critical applications. The PhD research project is within the framework of the longstanding NGI-INGV collaboration, increasingly consolidated in the framework of many international projects. NGI pioneered GPS ionospheric scintillation monitoring in Northern Europe with GISTM (GPS ionospheric scintillation and TEC monitor, Van Dierendonck et al., 1993; Van Dierendonck, 2001) receivers. Between June 2001 and December 2003, four units were installed in the UK and Norway mainland, covering the geographic latitudes from 53° N to 70° N. Data was stored and analysed, focusing on statistical analyses and impact for GNSS users (Rodrigues et al., 2004, Aquino et al., 2005a, Aquino et al., 2005b). These units were decommissioned in 2004 and, then, re-deployed together with additional new receivers, in UK, Norway, Italy and Cyprus. An additional station was deployed by the NGI in Dourbes, Belgium (in collaboration with the Royal Meteorological Institute of Belgium) between 2006 and 2011. INGV leads the ISACCO (Ionospheric Scintillation Arctic Campaign Coordinated Observations) project in the Arctic, started in 2003, in which frame the management of three GISTM receivers in Svalbard (De Franceschi et al., 2006) and another two at European mid-latitudes, Chania (Greece) and Lampedusa (Italy), is currently undertaken. The PhD research project contributed to the reinforcement of the NGI-INGV GISTM network developing monitoring, data management and quality tools. Such activities have supported the continuity and the control of the receiving stations, as well as the access and the preservation of the both real-time and historical data acquired. In fact, a robust, continuous data acquisition and a wise management of the GISTM network are of paramount importance for Space Weather applications, as they are the basis on which reliable forecasting and now-casting of possible effects on technological systems lean. Moreover, the possibility to use the data for scientific and applicative purposes depends upon well-established data quality procedures and upon a detailed knowledge of the sites in which each receiver comprising the network are deployed. Starting from these considerations, and in the framework of the aforementioned collaborative context, the PhD work aimed at improving the monitoring techniques and developing novel data processing to improve the data quality. Scintillation measurements are contaminated by multiple scattering encountered by the GNSS signal due to buildings, trees, etc. Such multipath sources need to be identified to keep the quality of the scintillation and TEC data as higher as possible. This can be achieved by removing these sources of errors or mitigating their effects by filtering the data. A novel station characterization technique has been introduced, developed and discussed in this thesis. The results demonstrated that this is a promising method to improve the quality of data (Romano et. al 2013). The results obtained so far motivated the development of the data filtering procedures. The filtering was aimed at filtering-out spurious, noisy data based on general assumptions about statistical data analysis (outlier analysis), thus efficiently removing multipath affected measurements and reducing the data loss with respect to applying a fixed elevation angle cut-off threshold. This is particularly important in case of not well covered regions (e.g. forests, deserts, oceans, etc.), as the field of view spanned by each antenna is optimized. During the PhD activities, the filtering technique has been also tested and validated against real and simulated data. To show how the development of the filtering method is able to efficiently clean multipath and signal degradation from GNSS data, it was applied in two different cases: - First, it was applied to the data published in a climatological study (Alfonsi et al. 2011), carried out with the NGI-INGV GISTM network at high-latitudes. Each station was characterized using the station characterization method, and then the data were filtered using the filtering method. Then, the new climatological maps were generated and compared to the original ones. The percentage of the filtered-out data obtained by applying the standard threshold of 20° on the elevation angle and the filtering technique for each station demonstrated how the latter is able to meaningfully reduce the data loss. The filtering extends the field of view of the network and, then, improves the capability of investigating the dynamics of the ionosphere over larger areas. - Second, the data used in this application were acquired by the CIGALA/CALIBRA network of PolaRxS receivers during the whole year of 2012. The elevation angle cut-off significantly reduced the capability of the network to depict the ionosphere northward of the geomagnetic equator and above the Atlantic Ocean, east of Brazil. This approach limited the data loss to 10-20%, while the traditional cut off of 15°-30° on the elevation angle led to losses of 35-45%. This method not only optimized the capability of GNSS networks, but also helped in planning the installation of additional new receivers aiming to enlarge network coverage in the framework of the CALIBRA project. The enlarged field of view made it possible to identify the increased occurrence of scintillation along the northern crest of the Equatorial Ionospheric Anomaly (EIA). To summarize and to introduce the reader into this thesis, specific issues here addressed are: - Development of software procedures and hardware designs to optimize the station configurations of the existing measurement network of GISTM (GPS Ionospheric Scintillation and TEC Monitor). - Development of techniques for remote, automatic instrument control and setting. - Development of data management tools to achieve quasi real-time data accessibility. - Development of data analysis methods to assess station characterization. - Development of techniques to perform data quality filtering. - Perform acquisition of experimental and simulation data. - Support scientific investigations through the high quality of the NGI-INGV network data.

A new type of space debris was recently discovered by Schildknecht in near -geosynchronous orbit (GEO). These objects were later identified as exhibiting properties associated with High Area-to-Mass ratio (HAMR) objects. According to their brightness magnitudes (light curve), high rotation rates and composition properties (albedo, amount of specular and diffuse reflection, colour, etc), it is thought that these objects are multilayer insulation (MLI). Observations have shown that this debris type is very sensitive to environmental disturbances, particularly solar radiation pressure, due to the fact that their shapes are easily deformed leading to changes in the Area-to-Mass ratio (AMR) over time. This thesis proposes a simple effective flexible model of the thin, deformable membrane with two different methods. Firstly, this debris is modelled with Finite Element Analysis (FEA) by using Bernoulli-Euler theory called “Bernoulli model”. The Bernoulli model is constructed with beam elements consisting 2 nodes and each node has six degrees of freedom (DoF). The mass of membrane is distributed in beam elements. Secondly, the debris based on multibody dynamics theory call “Multibody model” is modelled as a series of lump masses, connected through flexible joints, representing the flexibility of the membrane itself. The mass of the membrane, albeit low, is taken into account with lump masses in the joints. The dynamic equations for the masses, including the constraints defined by the connecting rigid rod, are derived using fundamental Newtonian mechanics. The physical properties of both flexible models required by the models (membrane density, reflectivity, composition, etc.), are assumed to be those of multilayer insulation. Both flexible membrane models are then propagated together with classical orbital and attitude equations of motion near GEO region to predict the orbital evolution under the perturbations of solar radiation pressure, Earth’s gravity field, luni-solar gravitational fields and self-shadowing effect. These results are then compared to two rigid body models (cannonball and flat rigid plate). In this investigation, when comparing with a rigid model, the evolutions of orbital elements of the flexible models indicate the difference of inclination and secular eccentricity evolutions, rapid irregular attitude motion and unstable cross-section area due to a deformation over time. Then, the Monte Carlo simulations by varying initial attitude dynamics and deformed angle are investigated and compared with rigid models over 100 days. As the results of the simulations, the different initial conditions provide unique orbital motions, which is significantly different in term of orbital motions of both rigid models. Furthermore, this thesis presents a methodology to determine the material dynamic properties of thin membranes and validates the deformation of the multibody model with real MLI materials. Experiments are performed in a high vacuum chamber (10-4 mbar) replicating space environment. A thin membrane is hinged at one end but free at the other. The free motion experiment, the first experiment, is a free vibration test to determine the damping coefficient and natural frequency of the thin membrane. In this test, the membrane is allowed to fall freely in the chamber with the motion tracked and captured through high velocity video frames. A Kalman filter technique is implemented in the tracking algorithm to reduce noise and increase the tracking accuracy of the oscillating motion. The forced motion experiment, the last test, is performed to determine the deformation characteristics of the object. A high power spotlight (500-2000W) is used to illuminate the MLI and the displacements are measured by means of a high resolution laser sensor. Finite Element Analysis (FEA) and multibody dynamics of the experimental setups are used for the validation of the flexible model by comparing with the experimental results of displacements and natural frequencies.

It has been reported that the use of recycled plastics is economical and environmentally-friendly. However, despite studies suggesting that properties of recycled plastics can be improved upon, there is very limited research which focuses on the application of recycled plastics in demanding industrial applications. Disappointingly recycled plastics have been almost totally neglected in the automobile production industry. This research investigates the use of recycled plastics in the production of automobile parts, starting by identifying of gap in knowledge between academic research and industrial practice. The only existing research into using recycled plastics in automobile production was focussed on closed-loop recycling. In this study, a review of current recycling practice was made with typical products analyzed in detail. It was found the mechanical, thermal and flammability properties of recycled plastics suffered noticeable deteriorations, while rheological properties were altered. Contaminants in recycled plastics were identified as elemental analysis was performed. At first, three representative fillers, i.e., talcum powder (talc), glass fibre (GF) and organically montmorillonite (OMMT), were selected to mix with recycled plastics to promote the desired properties. Their effects were compared. Experiments showed that GF was the most effective filler in improving most of the mechanical properties, and OMMT was the most effective in promoting flexural properties with the least loading. Talc and OMMT improved both the rheological and flammability performance of recycled plastics. For the first time, the recycled PP/talc composites were found to maintain better mechanical properties in ageing and reprocessing tests compared with virgin composites. At this initial stage, the effects of different coupling agents in compatilising recycled plastics and fillers were identified. For the study, four data analysis techniques were selected and used to predict, optimise and evaluate the formulae and procedures of recycled plastics: grey model (GM), Taguchi method (TM), principal component analysis (PCA) and cluster analysis (CA). Among these techniques, GM was successfully applied in predicting the effect of adding recycled plastic to virgin plastic based limited trials. TM was successfully applied in optimising injection moudling conditions when using recycled plastics. PCA and CA were successfully applied in analysis and evaluation of the performance of recycled plastics. This research found that with the addition of certain additives and the application of mathematical methods, recycled plastics and their corresponding composites showed potential in industrial apllications, since some properties of these composites were more favorable than those of industrial composites currently being used in automobile industry. The novel methodology developed in this research was successfully applied in the enhancement of mechanical properties of recycled plastics, an outcome which represented a crucial step towards large-scale utilization of recycled plastics in the production of automobile parts.

Electric and Hybrid Electric Vehicles [(H)EVs] are harder for pedestrians to hear when moving at speeds below 20 kph. Laws require (H)EVs to emit additional exterior sounds to alert pedestrians of the vehicles’ approach to prevent potential collisions. These sounds will also influence pedestrians’ impression of the vehicle brand. Current methods for evaluating (H)EV exterior sounds focus on “pedestrians’ safety” but overlook its influence on “vehicle brand”, and do not balance experimental control, correct context along with external and ecological validity. This research addresses the question: “How should (H)EV exterior sounds be evaluated?” The research proposes an experimental methodology for evaluating (H)EV exterior sounds that assesses pedestrians’ safety and influence on the vehicle brand by measuring a listener’s detection rate and sound quality evaluation of the (H)EV in a Virtual Environment (VE). This methodology was tested, improved and validated through three experimental studies based on their findings. Study 1 examined the fidelity of the VE setup used for experiments. The VE was immersive with sufficient degree of involvement/control, naturalness, resolution, and interface quality. It also explored a new interactive way of evaluating (H)EV sounds where participants freely navigate the VE and interact with vehicles more naturally. This interactivity increased the experiments’ ecological validity but reduced reliability and quadrupled the experiment duration compared to using a predefined scenario (non-interactive mode). Thus, a predefined scenario is preferred. Study 2 tested the non-interactive mode of the proposed methodology. Manipulating the target vehicle’s manoeuvre by varying factors, namely the vehicle’s “arrival time”, “approach direction” and “distance of travel”, across the experiment conditions increased ecological validity. This allowed participants to think, respond and pay similar attention as a real world pedestrian. These factors are neglected by existing methodologies, but were found to affect the participants’ detection rate and impression of the vehicle brand. Participants detected the vehicle more than once due to confusion with real world ambient sounds. In the real world, pedestrians continuously detect a vehicle in presence of non-vehicular ambient sounds. Therefore, recommendations to improve the representation of the real-world processes in the vehicle detection during listening experiments include an option to re-detect a vehicle and subjective evaluation of ‘detectability’ of the vehicle sounds. The improved methodology adds ‘detectability’ and ‘recognisability’ of (H)EV sounds as measures and (H)EV’s arrival time as an independent variable. External validity of VEs is a highly debated yet unanswered topic. Study 3 tested external validity of the improved methodology. The methodology accurately predicted participants’ real world evaluations of the detectability of (H)EV sounds, ranked order of the recognisability of (H)EV sounds and their impressions about the vehicle brand. The vehicle’s arrival time affected participants’ detection rate and was reaffirmed as a key element in the methodologies for vehicle sounds’ detection. The final methodological guidelines can help transportation researchers, automotive engineers and legislators determine how pedestrians will respond to the new (H)EV sounds.

Equivalent circuit models (ECM) are required to provide an on-board model of battery behaviour by battery management systems (BMS). The performance of ECMs is dependent on characterisation test results. The components of the ECM are commonly parameterised using electrochemical impedance spectroscopy (EIS) results, open circuit voltage (OCV) test results, and capacity test results. Therefore, these three tests are important for ECM parameterisation. Although the test procedures for these characterisation tests exist to test Li-ion cells for a range of applications e.g. portable electronic devices, they fail to provide essential information for automotive application due to the different requirements of vehicles (e.g. high power and energy, wide operating environment, long service life). This thesis reports research to improve consistency, accuracy and interpretation of characterisation test techniques for Li-ion battery cells for automotive application. The capacity of the battery pack is a vital parameter required for an ECM to estimate driving range. Existing techniques for predicting the driving range of an electric vehicle use the capacity value in Amp-hours, measured by existing capacity test techniques. In this thesis, experimental evidence that establishes the advantages of using capacity in Watt-hours instead of the capacity in Amp-hours as per the standard test is presented for the first time. Moreover, it is reported that measured battery capacity can vary by up to 5.0 % depending on the length of intermediate rest period. The OCV is another crucial parameter of ECM. The path dependence of OCV is a distinctive characteristic of Li-ion batteries which is known as OCV hysteresis. OCV test procedures used previously do not consider the initial conditions of the cells and capacity variations that show a change in OCV, leading to an apparent increase in, or erroneous, hysteresis. Using a new methodology which addresses issues mentioned above, OCV and OCV hysteresis has been quantified for different Li-ion cells for the first time. The test results show that a battery’s OCV is directly related to the discharge capacity, not the more commonly used SoC. The maximum hysteresis was found in a LiFePO4 (LFP) cell and lowest in a LTO cell, although still measurable. A dynamic hysteresis model is used to show how better OCV prediction accuracy can be achieved by a BMS when hysteresis voltage is a function of SoC instead of assuming it to be a constant, as traditionally done. EIS is commonly used to parameterise an ECM. For the first time this thesis reports that the time period between the removal of an electrical load and an EIS measurement affects the results. The study of five commercially available cells of varying capacities and electrode chemistries show that, regardless of the cell type, the maximum impedance change takes place within the first 4 hours of the relaxation period. Therefore a standardised relaxation period of minimum 4 hours should be allowed before performing EIS test. In addition to ECM parameterisation, EIS has been considered for online measurement, integrated with a BMS. This thesis concluded that the use of EIS as a fast measurement tool will be unreliable because of the relaxation effect. The flaws with capacity, EIS and OCV tests for automotive applications have been discussed. Through experimental evidence and electrochemical explanation it has been demonstrated that these tests can be made more consistent (e.g. by allowing fixed relaxation period in EIS test), have improved accuracy (e.g. incorporating hysteresis as a function of SoC) and better interpretation of test results (e.g. Watt-hours instead of Amp-hours in capacity test) are possible. Therefore, the overall contributions of this thesis to the scientific community are better consistency, accuracy and interpretation of these three tests. With the use of a case study, it has been shown that this new knowledge will improve performance of ECM, and thus BMS. This is not only for automotive but also more general applications through adopting the proposed new methodologies.

The crash of the Boeing 737-400 G-OBME at Kegworth on the 8th January 1989 provided an opportunity to investigate how the passengers were injured during the crash. A computer simulation was subsequently set up to assess the kinematics of the passengers and to establish the likely forces which they would have experienced during the crash. Two computer models were created using the crash victim simulation program, MADYMO. The models were used to study the brace and upright positions and to establish any correlation with body injuries and forces predicted by the models. A parametric study was, subsequently, undertaken with the objective of improving seat design. Further studies were undertaken to evaluate the effects of body posture and impact pulses upon 5th percentile female, 50th percentile male and 95th percentile male occupants. The objective of the research was to establish the severity of injuries for various occupant statures when seated in accordance with the dynamic seat requirements of Aerospace Standard 8049. The research was used to establish the loads sustained on the head, thorax, lumbar spine, pelvis and lower limbs. A three dimensional computer model was created with the objective of studying the effect of lateral acceleration components as specified in Aerospace Standard 8049. Furthermore, the model was used to establish the injuries which might be sustained in other types of aircraft accidents. Using the data of the same aircraft, this was further utilised to investigate different seat orientations and restraint systems. Finally, a spine model was created which examined the detailed loading of the spine using the 16G dynamic test pulse. This showed that the spine of a lap belted occupant is heavily loaded during the impact. Thus, the computer modelling of the brace for impact position led to the recommendation for a new improved brace position which could reduce the likelihood of lower limb flail. In addition, it has been found not to increase spinal loading.

The internal combustion (I.C.) engine remains unrivalled as the primary means of road vehicle propulsion. The frequency of re-fuelling stations, combined with the high energy density of both gasoline and diesel fuel provide users with unrivalled flexibility and vehicle range. However a range of environmental and health concerns exist surrounding I.C. engine emissions; in particular carbon dioxide (CO2), nitrous oxides (NOx), hydrocarbons (HC) and carbon monoxide (CO). There is therefore increasing pressure on vehicle OEMs to reduce vehicle emissions through tightened emission standards and regulations. A significant challenge in meeting these tightened regulations is the reduced efficiency of the I.C. engine during cold-start which reduces from typical values of 40% when fully warm to values as low as 10% when cold. Increased friction in the engine caused by overly viscous lubricants providing sub-optimal lubrication during cold starts is a primary cause of this reduction in efficiency during cold-start. This is despite the advancements in lubricant technology made that has reduced the sensitivity of lubricant viscosity to temperature variation. It is therefore desirable to increase the rate of lubricant heating during engine warm-up so that optimal lubrication conditions are reached sooner and frictional losses are reduced. The reduction in frictional losses therefore reduces fuel consumption and hence emissions. In this thesis, the merits of insulating engine oilways are investigated as a means to reduce thermal losses from the lubricant and thus accelerate warm-up rates using a bespoke oil flow rig and simulation model. Through this work, it has been found that, using insulating inserts, it is possible to reduce the thermal losses from the lubricant to the surrounding wall structure by up to 58%. Such reductions have been achieved by installing an insulating insert into the oilway (also commonly referred to as a gallery in I.C. engines) that combines a low thermal conductivity material but also introduces a contact resistance between the insert and the surrounding metal. It has been found that the contact resistance is a highly significant and beneficial feature and, using special inserts designed to enhance the contact resistance, reductions in thermal losses of up to 40% can be achieved using the contact resistance alone without using low thermal conductivity materials. A computational finite difference model has been developed to simulate heat transfer between flowing engine lubricant and the gallery walls. The model has been correlated with experimental data from the oil flow rig and is capable of simulating the effects of changing the materials properties (density, specific heat capacity and thermal conductivity) of both insulating inserts and the surrounding metal structure. The model is also capable of investigating the effect of changing contact heat transfer coefficients and changing flow geometry and velocity. Through computational experiments with this model, it has been found that the optimum strategy to achieving reduced thermal losses from the lubricant through the gallery walls is to ensure that the thermal conductivity of the insulating insert and that the thermal mass of the surrounding structure are minimised. Computational experiments have also highlighted the need to consider the flow geometry of different regions of the engine with the variation in bore diameter affecting both the heat transfer surface area and the convective heat transfer coefficient through the Reynolds’ effect. It has been found that increasing the lubricant flow velocity for a given bore diameter increases thermal losses to the gallery walls as a result of the Reynolds effect. If the bore diameter is increased, the thermal losses from the lubricant reduce in uninsulated galleries owing to a reduction in the Reynolds number but the reverse happens in insulated galleries owing to the increase in heat transfer area. The change in trend is a result of the interactions between the changing convective heat transfer area, heat transfer coefficient and the temperature differential between the lubricant and gallery wall. In addition, implementation of the insulation into a running engine needs careful consideration to ensure that the insulation does not isolate the lubricant from a potential heat source (such as the cylinder head). The optimum locations will vary between engines but investigations suggest that the return galleries from the head to the sump represent a positive opportunity to reduce thermal losses from the lubricant with a clear reduction in lubricant temperature observed as the lubricant moves down the gallery.

The experience of comfort is an important factor in passengers’ acceptance of transport systems. Comfortable cabin environments can be used as a means to differentiate between aircraft manufacturers and airlines and therefore, may be a key marketing feature. In 2010 and 2011, the European Commission presented its vision for aviation in the year 2050, highlighting the importance of enhancing passengers’ experiences. They also envisaged the use of virtual reality (VR) to provide aircraft passengers with entertainment and a means of ‘escaping from the fast pace of society’. The VR-HYPERSPACE project addressed this vision by examining the use of virtual and mixed reality technologies to enhance passenger comfort on aircraft in the year 2050. This approach to increasing comfort would be comparatively cheaper than changing the physical parameters of an aircraft. This thesis presents a series of studies which investigated the ways in which two virtual environments (VEs) that were developed for the VR-HYPERSPACE project (one depicting a tropical island and one depicting the view outside of a low-flying aircraft, referred to as the ‘invisible aircraft VE’) could influence potential aircraft passengers’ comfort and experiences. The findings from these studies provide insight into the prospect of using VR to enhance passengers’ comfort and experiences in future flight from a user-centred perspective. An initial user study was carried out to gain an understanding of the ways in which the two VEs, with various combinations of motion tracking, affected people’s comfort and experiences. The results of this study showed that the VEs have the potential to enhance people’s experiences, for example, by giving them an enhanced perception of space and time. They also might provide people with unique opportunities if used in flight, for example to augment or escape the flight experience. The study identified that motion tracking enhanced the experience of the invisible aircraft VE but detracted from the relaxing nature of the tropical island VE. The findings of this study were used to select combinations of VEs and motion tracking configurations to be taken forward for further investigation. The initial study also identified that it was difficult to determine the extent to which VEs could enhance comfort when the participants were not exposed to discomfort. Consequently, a new approach to measuring the effect of interventions on discomfort was developed. This involved a workshop and a user study which were carried out to select and test sources of discomfort. Two common sources of discomfort were selected: the sound of a crying baby and restricted legroom. These were used subsequently to induce discomfort in participants in later studies. The final series of studies aimed to determine the extent to which VEs could distract people from sources of discomfort. The findings indicated that passive VEs could be used to either fully distract people from sources of discomfort or minimise their negative responses. However, the VE used was more effective at distracting people from the discomfort associated with restricted legroom than the sound of a crying baby. The findings indicated that VEs become more distracting when they are interesting and that when exposed to stressful stimuli, relaxing distractors may be beneficial. The findings also indicated that VEs can be used to support existing strategies which people might use to overcome sources of discomfort in present-day flight situations. This research considered existing research in both the comfort and the pain domains to develop a novel approach to enhancing passenger comfort through the use of VEs. The research showed that VEs have the potential to distract people from sources of discomfort which are commonly experienced in-flight and to enhance potential passengers’ flight experiences. Further investigation is required to understand whether VEs remain effective distractors over longer periods of time, when subject to multiple sources of discomfort and in real-world contexts.