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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1061

Cross-cultural effects on drivers' hazard perception : validating a test paradigm for developing countries

Lim, Phui Cheng January 2017 (has links)
The hazard perception skill of a driver refers to their ability to identify potentially dangerous events on the road, and is one of the only driving-specific skills that has been consistently linked to accident rates. Hazard perception tests are used in several developed countries as part of the driver licensing curriculum, however little research has been done in developing countries where road safety is a primary concern. The extent to which hazard perception skill transfers to different driving environments is also unclear. This thesis therefore has two major aims: to examine hazard perception in a cross-cultural context, and to validate a hazard perception test for potential use in driver licensing in lower-income, developing countries. Most of the experiments in this thesis compare hazard perception skill in drivers from the UK – where hazard perception testing is well established – and drivers from Malaysia – a developing country with a high accident rate where hazards frequently occur. Typically, hazard perception skill is assessed by showing participants clips filmed on the road and asking them to respond as soon as they detect a developing hazard, with shorter response times reflecting greater levels of skill. Chapter 2 presents evidence that Malaysian drivers may be desensitized to hazardous road situations and thus have increased response times to hazards, creating validity issues with the typical paradigm. Subsequent chapters therefore use a predictive paradigm called the “What Happens Next?” test that requires drivers to predict hazards, leaving performance unaffected by hazard desensitization. Malaysian drivers predicted hazards less accurately than UK drivers in all cross-cultural experiments, indicating that exposure to a greater number of hazards on Malaysian roads did not have a positive effect on participants’ predictive hazard perception skill. Further experiments indicated that explicit knowledge plays a minor role in the “What Happens Next?” test, and that experienced drivers appear to compensate for reduced visual information more effectively than novices. Experienced drivers from both Malaysia and the UK also outscored novices in all experiments using the predictive paradigm, suggesting the “What Happens Next?” test provides a valid measure of hazard perception skill and may offer a practical alternative for hazard perception testing in developing and even developed countries.
1062

Proposta para implementação de uma bancada dinamométrica automatizada para ensaios em tempo real de motores de combustão interna do ciclo Otto / Proposal for implementation of an automated dynamometric bench for tests in real time of internal combustion engines of the Otto cycle

Bezerra, Adriano Carlos Nogueira 05 May 2000 (has links)
Com o advento da crise do petróleo na década de 70, os motores, que antes eram calibrados para fornecer máximos torque e potência, após a crise passaram a ser calibrados de forma a fornecer consumo específico e emissões mínimos. A partir de então os motores passaram a ser ensaiados em bancadas dinamométricas que possuíam módulo para medição de emissões e que simulavam condições mais reais de tráfego, segundo um ciclo de ensaios preestabelecido. Este trabalho contém um levantamento bibliográfico sobre o instrumental, metodologias e procedimentos utilizados nos ensaios dinamométricos permanentes e dinâmicos e propõe a implementação de uma metodologia para realização de ensaios em tempo real controlado por computador. Traz também os resultados experimentais relativos à parte da metodologia que foi implementada. / With the advent of petroleum crisis in the 70\'s, engines, previously calibrated in order to supply maximum momentum and power, after the crisis they started being calibrated to supply minimum specific consumption and emissions. After this, engines started being tested in dynamometric benches equipped with emission measure modules and that simulate traffic conditions closer to reality, according to a prior emissions cycle. This work contain a bibliographic survey about instruments, methodologies and procedures used in the steady-state and dynamic dynamometric tests and proposes the implementation of a methodology to perform real time tests controlled computationally. It brings too experimental results related to the implemented methodology.
1063

Computationally inexpensive parallel parking supervisor based on video processing

Espejo Pérez, Caterina María 05 December 2013 (has links)
Parallel parking, in general, is a moderate difficulty maneuver. Moreover, for inexperienced drivers, it can be a stressful situation that can lead to errors such as stay far from the sidewalk or damage another vehicle resulting in traffic tickets that range from simple parking violation to crash-related violations. In this work, we propose a computationally effective approach to perform a collisionfree parallel parking. The method will calculate the minimum parking space needed and then the efficient path for the parallel parking. This method is computationally inexpensive in comparison with the current state of the art. Moreover, it could be used by any car because the parameters needed to perform all computations are taken from the specifications of real cars. Preliminary results of this work were summarized in [1] that was presented at the 15th International IEEE Conference on Intelligent Transportation Systems. The simulation and experimental data show the effectiveness of the method. This effectiveness is specified when the path followed by the driver and the path calculated with the method are compared. The image capture of the vehicle is used to get the path made by the driver for the parallel parking. Furthermore, road surface marks were determined (in a parking lot) as a visual aid for the drivers in order to perform the parallel parking maneuver. After analyzing the paths, it is noted that the vehicles that properly followed the marks, parked correctly. / Tesis
1064

Measuring speech motor skills in phonologically disordered pre-school children and their normally developing peers

Cohen, Wendy Melissa Myers January 1999 (has links)
Previous research has demonstrated that normally developing children are expected to have adult like control of their speech production skills by 10 years of age, as evidenced by increases in speed of production and decreases in performance variability. (e. g. Kent and Fortier 1980). There is also some evidence to suggest that phonologically disordered children may have poorer speech motor skills than their normally developing peers (e. g. Henry 1990, Edwards 1992, Waters 1992, Towne 1994). There are numerous techniques that can be used to measure a number of different aspects of speech motor control. However, there are methodological difficulties in devising appropriate protocols for the collection and analysis of speed of speech production as used as an index of speech motor skill in young children. Some of the techniques that have had clinical application include measurement of rate in connected speech production and measurement of diadochokinetic (DDK) repetition rate. This investigation compared normally developing and phonologically disordered preschool children on various indirect measures of speech motor skills, in imitated and spontaneous connected speech and in DDK tasks. The investigation also focused on refining the techniques of data collection and analysis appropriate to young children. While the results vary with regard to the statistical significance of the differences between the two groups of children on articulation rates and DDK rates, analysis of the error patterns in single word, spontaneous connected speech, imitated connected speech and DDK productions identified a sub group of phonologically disordered children who may present with an underlying speech motor deficit as the basis of their phonological disability. The results of the investigation are considered in terms of their implication for the speech motor skills of the two groups of children, techniques for measuring various aspects of speech motor skill and the clinical identification of phonologically disordered children who have an underlying speech motor deficit.
1065

A study of cultural models in automotive HMI : framework for accommodating cultural influence

Khan, Tawhid January 2016 (has links)
This doctoral innovation report presents a research study examining the importance of understanding automotive users’ cultural values and their individual preferences for HMI features and functionalities. The goal of this research was to explore how a cultural model can be applied in the development of automotive HMI solutions and future design localisation. To meet this goal, it was necessary to (1) identify the characteristics of the Hofstede cultural model; (2) identify the differences in cultural values using the model; (3) identify differences in HMI design preferences, usability and task performances across automotive user groups; (4) identify the potential success of a culturally adapted automotive HMI solution in automotive user acceptance and satisfaction. To explore the differences between users from two cultural regions, India and the UK, a series of user-centered HMI evaluation studies are conducted in which participants from each cultural region evaluate representative HMI samples. The outcomes of the user studies generate good quality data about automotive users’ cultural values and its relationship with vehicle user interface usability, task performances, and their feature preferences. The results are used in the development of a conceptual culturally adapted HMI design solution. This conceptual design is evaluated during the application phase of the research in order to explore whether such a design solution has a greater level of learnability and usability compared to the conventional solution when evaluated by Indian drivers. The results are also analysed to identify specific cultural traits that may influence the intention to use such solution in emerging markets like India. The outcome of the study shows different cultural groups have different behavioural tendencies and performances while using vehicle HMI solutions and have differences in expectations in design, suggesting an influence of culture on the perception of vehicle user interface technology. The analysis also highlights a preference for the culturally adapted automotive HMI solution when Indian drivers are provided with a choice between this and a non-adapted conventional solution. This leads to the conclusion that an understanding of cultural biases can influence design localisation and, as such, culturally-generated theories and recommendations can be applied as a basis for future automotive HMI design and development.
1066

Effective vehicle attribute delivery at Jaguar Land Rover : innovation report

Davis, Martin January 2017 (has links)
The objective of this research is to enhance the effectiveness of the new product development at Jaguar Land Rover by attending to the incongruities between the perceived organisational culture and the ecosystem in which the teams operate. The inquiry is aligned with both Donaldson's structural contingency theory (2001) and Syed's (2015) reflections regarding psychological alignment. The contention of the research is that an alternative operating model enables the teams to thrive and relish the uncertain, complex environment in which they now operate and hence improve their satisfaction and wellbeing whilst delivering increased value for both the business and the consumers (Davis, 2016a). This paper describes the rationale and the approach taken to embed an operating model which liberates the capabilities of the 'knowledge worker' community (Drucker, 1999) as opposed to the apparent Scientific Management (Taylor, 1914) bureaucratic efficiency model, which had previously been relevant. The research methodology incorporates Research Oriented Action Research (Eden and Huxham, 1996) in order to accommodate the unknowable outcomes and embedded paradoxes. The incorporation of a neurological metaphor attends to the innate human behaviours and social dynamics, whilst Dissipative Structure Theory (Prigogine and Allen, 1982) and the concept of panarchy (Garmestani et al., 2008) expands the traditional hierarchical perspective. The joint inquiry undertaken during an internship at Airbus Defence and Space corroborated the notion that an agile operating model could be realised for the creation of complex systems with significant hardware content and long lead times. The investigation also merges the constructive lean/agile values and principles from other sectors that are facing similar disruption in their ecosystems. The adoption of the principles that support self-determination (Ryan and Deci, 2000) result in reframing the participants' beliefs or "theories of action" (Argyris, 1995) by revising their experiences, hence a reduction in the observable stress and a verifiable increase in the delivery of valuable outcomes. The implications of the research spans both academic interest and real world utility regarding the co-creation of valuable knowledge through the alignment of the social dynamics of the participants and the methodology for progressing volatile problem situations with the ecosystems in which they find themselves.
1067

Fuel pump motor-drive systems for more electric aircraft

Skawinski, Grzegorz January 2010 (has links)
The fuel systems fitted to the current generation of civil transport aircraft are rather complicated, due to the presence of multiple tanks, pumps, valves and complex pipeline systems. During fuel transfer between the tanks, when controlling the aircraft centre of gravity or engine feed and refuel operations, a number of pumps and valves are involved resulting in complex pressure and flow interactions. In order to minimise the pressure surges during sudden system changes and flow overshoot during fuel transfer and refuelling, different motor drive system control strategies have been investigated. It is proposed that the current control method of electrically driven centrifugal-type pumps could be replaced by improved open and closed loop strategies where the flow overshoot can be minimised and pressure surges reduced. Steady-state and dynamic models of an AC induction motor drive and typical aircraft fuel system pipework components have been developed. The validation of these models has been performed using experimental data obtained from a fuel test rig constructed at the University of Bath using water as the working fluid. The simulation results have been shown to agree well with those from experimentation. In addition, the induction motor has been modelled based on its physical properties using the Finite Element Method software MEGA. The investigated fuel system has been described in linear terms and its behaviour has been identified. It is shown that the system dynamic behaviour can be controlled/improved using well established closed loop proportional-integral control. An open loop technique of simultaneous pump and valve control has been proposed and validated using experimental results, resulting in a reduction of both the transient pressure surges and flow overshoot during sudden valve closures, showing significant performance improvements. Improved closed loop control strategies for the pump drive system have also been developed in simulation. These are based on adaptive proportional-integral-derivative and fuzzy logic control strategies.
1068

Characterization of Motor Unit Discharge Rate in Patients with Amyotrophic Lateral Sclerosis

Kasi, Patrick K 04 May 2009 (has links)
In this study, we used a custom made quadrifilar needle electrode and multichannel electromyography (EMG) software tool to decompose EMG signals and investigate the behavior of motor unit discharge rate (MUDR) of concurrently active motor units in patients with amyotrophic lateral sclerosis (ALS). Decomposition is a technique used to break down the complex EMG signal into its constituent motor units. A motor unit is a single alpha motor neuron and all the muscle fibers it innervates. ALS is a progressive degenerative disorder of both the upper and lower motor neurons. We recorded four differentially amplified EMG signals from the first dorsal interosseous (FDI) muscle of six ALS patients (four with predominant lower motor neuron pathology and two with predominant upper motor neuron pathology) and seven control subjects. Recordings were made from force contractions of 20 and 50% of maximum voluntary contraction (MVC). All control subjects were between the ages of 40 and 70 years and were examined by a practicing physiatrist for exclusion criteria including neuromuscular disorders or any medications that might affect muscle activity. We observed differences in initial firing rates and variability of active motor units between control subjects and ALS patients. Furthermore we observed differences in firing rates and variability of active motor units between ALS patients with predominant upper motor neuron pathology and ALS patients with predominant lower motor neuron pathology. Initial motor unit firing rates for control subjects were 16.22 +/- 2.06 Hz at 20% MVC and 19.79 +/- 1.66 Hz at 50% MVC. As expected, initial motor unit firing rates from patients with predominant lower motor neuron pathology were higher than those of control subjects; 18.87 +/- 4.73 Hz at 20% MVC and 24.28 +/- 5.01 Hz at 50% MVC. ALS patients with predominant upper motor neuron pathology, as expected, had initial motor unit firing rates that were lower than those observed in control subjects; 9.22 +/- 1.68 Hz at 20% MVC and 12.83 +/- 2.26 Hz at 50% MVC. Motor unit firing rate time series in ALS patients with predominant upper motor neuron pathology showed decreased variability, 0.99 +/- 0.17 Hz at 20% MVC and 1.70 +/- 0.52 Hz at 50% MVC, when compared to control subjects, 2.37 +/- 0.67 at 20% MVC and 4.20 +/- 1.00 at 50% MVC. Variability of motor unit firing rate time series in ALS patients with predominant lower motor neuron were high, 3.38 +/- 1.2 Hz at 20% MVC and 4.07 +/- 1.56 Hz at 50% MVC, compared to control subjects. At 50% MVC, motor unit substitution was observed in ALS patients with predominant upper motor neuron pathology despite the contractions lasting just a few seconds. Motor unit action potentials (MUAPs) recorded from patients were polyphasic when compared to those from control subjects, as is characteristically found in practice.
1069

Electromechanical System Integration for a Powered Upper Extremity Orthosis

Scarsella, Michael John 17 April 2007 (has links)
Wearable robotics for assistance and rehabilitation are not yet considered commercially mainstream products, and as a result have not yet seen advanced controls systems and interfaces. Consequently, the available technology is mostly adapted from systems used in parallel technologies, rather than custom applications intended for human use. This study concerns itself with the design and development of a custom control system for a 2-degree of freedom powered upper extremity orthosis capable of driving elbow flexion/extension 135º and humeral rotation 95º . The orthosis has been evaluated for use as both a long-term assistive technology device for persons with disabilities, and as a short-term rehabilitative tool for persons recovering injury. The target demographics for such a device vary in age, cognitive ability and physical function, thus requiring several input parameters requiring consideration. This study includes a full evaluation of the potential users of the device, as well as parameter considerations that are required during the design phase. The final control system is capable of driving each DOF independently or simultaneously, for a more realistic and natural coupled-motion, with proportional control by pulse-width modulation. The dual-axis joystick interface wirelessly transmits to the 1.21 pound control pack which houses a custom microcontroller-driven PCB and 1800 milliamp-hour lithium-ion rechargeable battery capable of delivering 4 hours of running time. Upon integration with the 2 DOF orthosis device, a user may complete full range of motion with up to 5 pounds in their hand in less than 7 seconds, providing full functionality to complete acts of daily living, thus improving quality of life.
1070

Consumer adoption of fuel cell vehicles : lessons from historical innovations and early adopters of battery electric vehicles

Hardman, Scott John January 2016 (has links)
Fuel cell vehicles (FCVs), are one possible solution to address transportation-related climate change, urban air pollution and fossil fuel resource depletion. To solve these issues they need to displace internal combustion engine vehicles (ICEVs), the aim of this thesis is to understand whether FCVs can achieve this. First case studies of successful historical innovations are explored. Second the consumer adoption of battery electric vehicles (BEVs) is studied in detail by using questionnaire surveys and in-depth interviews. Finally, consumer attitudes and perceptions towards FCVs are investigated by conducting in-depth interviews and a FCV trial. From all of these results this thesis finds that FCVs have fewer benefits as perceived by consumers compared to BEVs and ICEVs. This means that consumers may preferentially adopt BEVs and will not be attracted to FCVs. This thesis makes recommendations on how to improve the attributes of FCVs so that they have more benefits for consumers. These efforts would increase the likelihood of consumers adopting FCVs. However, this thesis suggests that the adoption of FCVs still looks unlikely and that fuel cell (FC) stakeholders should seek to concentrate their efforts towards applications of FCs that have viable market entry potential.

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