Thesis (DTech (Mechanical engineering))--Cape Technikon, 1997 / This study forms the basis from which the aerodynamic drag of a practical supersonic inlet can be predicted. In air-breathing propulsion systems, as used in high performance flight vehicles, the fuel is carried onboard and the oxygen required for combustion is ingested from the ambient atmosphere. The main function of the inlet is to compress the air from supersonic to subsonic conditions with as little flow distortion as possible. When the velocity of the vehicle approaches or exceeds sonic velocity (M = 1,0) a number of considerations apply to the induction system. The reason for this is that the velocity of the ingested air has to be reduced to appreciably less than sonic velocity, typically to M = 0,3. Failure to do so will cause the propulsion system to be inoperative and cause damage. In the process of compressing the air from supersonic to subsonic conditions a drag penalty is paid. The drag characteristics are a function of the external geometry and internal flow control system of the inlet. The problem which was investigated dealt with drag of a specific type of inlet, namely a two-dimensional external compression inlet. This study is directed at formulating definitive relationships which can be used to design functional inlet systems. To this effect the project was carried out over three phases, a theoretical investigation where a fluid-flow analysis was done of the factors influencing drag. The second phase covered a comprehensive experimental study where intensive wind-tunnel tests were conducted for flight Mach numbers of M = 1,8; M = 2,0; M = 2,2; M = 2,3 and M = 2,4. During the third phase a comparison, between the theoretical values and experimental data was done, for validating the predicted aerodynamic drag figures. The following findings are worth recording: • the increase in total drag below the full flow conditions is more severe than predicted due to the contribution of spillage drag; • the range for subcritical mode of operation is smaller than expected due to boundary layer effects. The study has shown that reasonably good correlation could be achieved between the theoretical analysis and empirical test at low subcritical modes of operation. This suggests that the study has achieved its primary objective.

Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV) are seen as solutions to meet the rising demand of consumers whilst overcoming challenges such as dependency on fossil fuels and carbon dioxide emissions. The success of these vehicles is highly dependent on reliable and efficient Energy Storage Systems (ESS). In order to build a reliable and efficient ESS system, a cylindrical lithium-ion cell is the most prominent choice since it has good energy density and favourable charging and discharging properties. Arrays of lithium-ion cells are connected in series and parallel to build the high power ESS system. These connections are realised by Battery Tab Joints. The durability and performance of the ESS system depends on the battery tab joint. Hence, the battery tab joint should be capable of enduring the static and dynamic mechanical loads as well as the electrical load. In order to understand battery tab joint behaviour, the performance (both mechanical and electrical properties) of battery tab joints were investigated under mechanical and electrical load. Resistance Spot Welding (RSW) was selected as the joining technique. RSW process parameters were optimised to achieve consistent nugget size and weld quality. The materials selected for investigation were nickel plated steel and nickel plated copper. In order to understand the mechanical and electrical behaviour of spot welded joints under mechanical and electrical load a test environment was designed to allow quasi-static and dynamic (fatigue) testing of tensile coupons and lap-shear welded specimens under electrical load. Temperature change and electrical properties were recorded during the tests. During fatigue test of lap-shear joints for different electric current load, it was found that the change in electric contact resistance (ECR) ratio up to the point of fatigue failure of joints was 0.1 and 0.2 for steel and copper respectively. Importantly, it was suggested that the change in ECR could act as a prediction mechanism for joint failure in a real ESS. It was found that electric current load has no observable effect on fatigue life of the battery tab joints. A computer-based model was developed to simulate weld damage and it was found to be in good agreement with experimental results. The effect of preload arising during battery pack manufacture was investigated. It was found that preload (without electric current load) had significant impact on fatigue performance of the battery tab joints.

The current drive to generate energy from sustainable renewable resources has led to an increased interest in generating power through exploiting the kinetic energy in faster flowing tidal streams. Much of the knowledge gained from the development of wind turbines has been applied to the tidal stream turbine. However, the hostile marine environment introduces new technological challenges. The tidal turbine operates under highly unsteady, turbulent flow conditions and the occurrence of marine biofouling adds further complication to the issue. The main objective of the present work is to advance the understanding of the effect marine fouling has on the unsteady hydrodynamic loading and performance of tidal turbine blade sections. To investigate this challenging fluid phenomenon, a series of two-dimensional static and unsteady experiments were designed and conducted in the dynamic stall test rig at the University of Glasgow's Handley Page wind tunnel facility. The test matrix was constructed to cover the full operating envelope of a blade from MW-scale turbines, and included three thicker, cambered blade sections from two radial positions on the blade - a NACA 63-619 and two proprietary AHH designs. Chordwise integrated force and pitching moment coefficients were obtained from surface pressure measurements for three representative blade fouling configurations: an aerodynamically clean baseline; a light level of widely distributed microfouling roughness; and the addition of macrofouling with a single instrumented barnacle protuberance. This work has generated what is believed to be a unique database of unsteady tidal turbine blade section performance and, more importantly, the negative impact marine biofouling is likely to have on these investigated parameters. The approach followed through the work has been to assess the impact of marine biofouling on the individual blade sections and then assess the consequences of marine biofouling on the turbine by combining the blade section findings in a BEMT numerical performance model.

Self-pierce riveting (SPR) is the core joining technology used by Jaguar Land Rover (JLR) to join aluminium & mixed material body in white (BIW). Currently, the application of this process has a serious constraint to the business due to the high investment and intensive labour required by physically testing joint feasibility. This is a critical issue especially where different stacks need to be joined by one SPR gun. In this case, the selection of a common rivet/die combination which suits different material stacks requires labour intensive work that in some cases can create long delays during a vehicle development and commissioning. In this context, the development of a simulation technique, based on Finite Element Analysis (FEA), could allow virtual assessment of the manufacturing feasibility of a joint. This will enable significant business benefits including: saving time, costs and materials requirement for the experimental trials. Three major challenges need to be addressed: short CPU time, accuracy and robustness in order for its application in a manufacturing environment. To achieve these objectives, detailed numerical methods capable of reproducing the key factors affecting the experimental process like tooling, boundary conditions and material plastic deformation are developed. For the first time, a thermo-mechanical finite element model for simulation of the SPR process has been proposed. This allowed consideration of the increase in temperature due to friction and plastic deformation generated during the rivet insertion. The effect of thermal softening and strain hardening were characterized for the development of the substrate material model and their influence on the numerical simulation was assessed. This study has been validated via production line data and a significantly high level of correlation between simulation and experimental data for over 1000 joints representative of a vehicle platform has been achieved. The application of the developed simulation technique will enable several business benefits such as significant reduction of engineering time and costs in contrast to the experimental procedure. These advantages allow a smooth implementation of the SPR process in a JLR production line by providing engineering recommendations rapidly and consistently. All these features, combined with accuracy and robustness have enabled the application of the developed tool into JLR business.

Active pedestrian safety systems can help to significantly increase pedestrian road safety, but must be tested very carefully before used in series application. Since there is usually a very small amount of time to prevent the collision, the activation of an emergency brake is always a critical decision. On the other hand, of course, false triggerings must be prevented. Aiming to increase pedestrian and vehicle safety, this thesis presents a novel approach for the test of active pedestrian safety systems. From the question "What is needed to test and compare future active pedestrian safety systems?" are resulting the following questions: 1. What are the significant characteristics of real pedestrians? 2. How can this features be mapped to a test system? This thesis presents characteristic features of pedestrians from the perspective of automotive surround sensors and introduces a novel test system approach including a realistic pedestrian dummy which is able to replicate those characteristics. Furthermore it introduces a novel active pedestrian safety test methodology, based on the variation of target characteristics, environmental conditions and driver behaviour. The proposed pedestrian dummy was set up in real size and tested on the test track in vehicle tests. A video of the described test and the novel pedestrian dummy can be seen here: https://youtu.be/eF5IkqsknBE

Advanced Driver Assistance Systems (ADAS) aids the driver by providing information or automating the driving related tasks to improve driver comfort, reduce workload and improve safety. The vehicle senses its external environment using sensors, building a representation of the world used by the control systems. In on-road applications, the perception focuses on establishing the location of other road participants such as vehicles and pedestrians and identifying the road trajectory. Perception in the off-road environment is more complex, as the structure found in urban environments is absent. Off-road perception deals with the estimation of surface topography and surface type, which are the factors that will affect vehicle behaviour in unstructured environments. Off-road perception has seldom been explored in automotive context. For autonomous off-road driving, the perception solutions are primarily related to robotics and not directly applicable in the ADAS domain due to the different goals of unmanned autonomous systems, their complexity and the cost of employed sensors. Such applications consider only the impact of the terrain on the vehicle safety and progress but do not account for the driver comfort and assistance. This work addresses the problem of processing vision sensor data to extract the required information about the terrain. The main focus of this work is on the perception task with the constraints of automotive sensors and the requirements of the ADAS systems. By providing a semantic representation of the off-road environment including terrain attributes such as terrain type, description of the terrain topography and surface roughness, the perception system can cater for the requirements of the next generation of off-road ADAS proposed by Land Rover. Firstly, a novel and computationally efficient terrain recognition method was developed. The method facilitates recognition of low friction grass surfaces in real-time with high accuracy, by applying machine learning Support Vector Machine with illumination invariant normalised RGB colour descriptors. The proposed method was analysed and its performance was evaluated experimentally in off-road environments. Terrain recognition performance was evaluated on a variety of different surface types including grass, gravel and tarmac, showing high grass detection performance with accuracy of 97%. Secondly, a terrain geometry identification method was proposed which facilitates semantic representation of the terrain in terms of macro terrain features such as slopes, crest and ditches. The terrain geometry identification method processes 3D information reconstructed from stereo imagery and constructs a compact grid representation of the surface topography. This representation is further processed to extract object representation of slopes, ditches and crests. Thirdly, a novel method for surface roughness identification was proposed. The surface roughness descriptor is then further used to recommend a vehicle velocity, which will maintain passenger comfort. Surface roughness is described by the Power Spectral Density of the surface profile which correlates with the acceleration experienced by the vehicle. The surface roughness descriptor is then mapped onto vehicle speed recommendation so that the speed of the vehicle can be adapted in anticipation of the surface roughness. Terrain geometry and surface roughness identification performance were evaluated on a range of off-road courses with varying topology showing the capability of the system to correctly identify terrain features up to 20 m ahead of the vehicle and analyse surface roughness up to 15 m ahead of the vehicle. The speed was recommended correctly within +/- 5 kph. Further, the impact of the perception system on the speed adaptation was evaluated, showing the improvements in speed adaptation allowing for greater passenger comfort. The developed perception components facilitated the development of new off-road ADAS systems and were successfully applied in prototype vehicles. The proposed off-road ADAS are planned to be introduced in future generations of Land Rover products. The benefits of this research also included new Intellectual Property generated for Jaguar Land Rover. In the wider context, the enhanced off-road perception capability may facilitate further development of off-road automated driving and off-road autonomy within the constraints of the automotive platform.

No description available.

Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 144-151). Also available in electronic format on the Internet.

Thesis (M. Sc.)--University of Hong Kong, 1995. / Includes bibliographical references (leaf [110-114]).

This thesis explores potential cultural needs appropriate to the design of in-vehicle navigation systems (IVNS). Such research is important given the increasing popularity of IVNS worldwide and the potential impact of their designs on increasing driver's satisfaction which leads towards safe driving environment. A review of the literature showed paucity in considering drivers' cultural values for navigational interfaces. The overall aim of the thesis was to explore characteristics of potentials driver's cultural needs for IVNS Four empirical studies are described in the thesis to address cultural issues in drivers' behaviour when engaging with IVNS. The exploration took a bottom-up approach, applying different methods and study designs in an effort to cater for potential cultural needs. A non-structured direction giving study, an online survey, a structured direction giving study and a scenario-based design study were used to explore for potential driver's cultural needs. The non-structured direction giving study and the online survey were baseline research aiming to explore driver's navigation behaviour and perception in basic conditions (between drivers and road environment). The non-structured direction giving study utilised participants from four nations, representing different cultural backgrounds; United Kingdom (UK), Malaysia, China and Japan in UK environment. The online survey collected opinions from UK, Malaysia and Japan local drivers. The different cultural groups showed some suggestions of driver's cultural needs. The structured direction giving study and the scenario-based design study utilised participants from UK and Malaysia to investigate the reliability and characteristics of driver's cultural needs for use in navigational interface. The four studies showed reliable navigational elements emerging from culturally different environments. Based on the categorisation scheme developed by UK drivers in UK environment, a cultural framework was proposed. The framework makes a distinction of navigational elements into three attributes; basic, trueness and personal. Ego directions and landmarks were consistently used in constructing navigational instructions, suggesting their importance as a basic requirement in designing IVNS interfaces. In relation to trueness of road environment in structuring navigational instructions, junction types and road geometries were commonly used in foreign environments. Differences were observed in navigational instructions across culturally-different drivers for their nation-state environments, suggesting the need to cater for personal preferences in designing IVNS interfaces. Another finding to emerge from the four studies was the need to address how to display satisfactory information density on the interface according to cultural groups. For future work, the proposed cultural framework could be used in developing culture-specific prototypes of IVNS.